Document:

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                                                                  Exhibit 10.16

                                  HILL BUILDING
                     Lease to Pharmaceutical Peptides, Inc.

                                Table of Contents

1.    Recitals and Definitions..............................................   1
      1.1   Recitals........................................................   1
      1.2   Definitions.....................................................   1

2.    Premises and Term.....................................................   2
      2.1   Premises........................................................   2
      2.2   Appurtenant Rights..............................................   3
      2.3   Landlord's Reservations.........................................   3
      2.4   Parking.........................................................   4

3.    Rent and Other Payments...............................................   4
      3.1   Annual Fixed Rent...............................................   4
      3.2   Real Estate Taxes...............................................   5
      3.3   Operating Expenses..............................................   8
      3.4   Inspection and Audit............................................  12
      3.5   Electricity.....................................................  12
      3.6   Other Utility Charges...........................................  13
      3.7   Above-Standard Services.........................................  13
      3.8   No Offsets......................................................  14
      3.9   Security Services...............................................  14
      3.10  Net Lease.......................................................  14

4.    Alterations...........................................................  14
      4.1   Consent Required for Tenant's Alterations.......................  14
      4.2   Ownership of Alterations........................................  15
      4.3   Construction Requirements for Alterations.......................  15
      4.4   Payment for Tenant Alterations..................................  16
      4.5   Tenant's Initial Improvements...................................  17
      4.6   Security for Performance of Tenant's
            Initial Improvements............................................  19
      4.7   Use of Roof.....................................................  24

5.    Responsibility for Condition of Building and
      Premises..............................................................  26
      5.1   Maintenance of Building and Common Ar
            eas by Landlord.................................................  26
      5.2   Maintenance of Premises by Tenant...............................  27
      5.3   Delays in Landlord's Services...................................  27

6.    Tenant Covenants......................................................  28
      6.1   Permitted Uses..................................................  28
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      6.2   Laws and Regulations............................................  29
      6.3   Rules and Regulations...........................................  29
      6.4   Safety Compliance...............................................  30
      6.5   Landlord's Entry................................................  30
      6.6   Floor Load......................................................  30
      6.7   Personal Property Tax...........................................  30
      6.8   Assignment, Subleases or other Transfers........................  30

7.    Indemnity and Insurance...............................................  33
      7.1   Indemnity.......................................................  33
      7.2   Liability Insurance.............................................  34
      7.3   Personal Property at Risk.......................................  35
      7.4   Waiver of Subrogation...........................................  35
      7.5   Landlord's Insurance............................................  36

8.    Casualty and Eminent Domain...........................................  36
      8.1   Restoration Following Casualties................................  36
      8.2   Landlord's Termination Election.................................  37
      8.3   Tenant's Termination Election...................................  37
      8.4   Casualty at Expiration of Lease.................................  38
      8.5   Eminent Domain..................................................  38
      8.6   Rent After Casualty or Taking...................................  39
      8.7   Temporary Taking................................................  39
      8.8   Taking Award....................................................  39

9.    Default...............................................................  39
      9.1   Tenant's Default................................................  39
      9.2   Damages.........................................................  41
      9.3   Cumulative Rights...............................................  42
      9.4   Landlord's Self-help............................................  42
      9.5   Enforcement Expenses............................................  43
      9.6   Late Charges and Interest on
            Overdue Payments................................................  43
      9.7   Landlord's Right to Notice and Cure.............................  43

10.   Mortgagees' Rights....................................................  44
      10.1  Subordination...................................................  44
      10.2  Prepayment of Rent not to Bind Mortgagee........................  44
      10.3  Tenant's Duty to Notify Mortgagee:
            Mortgagee's Ability to Cure.....................................  44
      10.4  Estoppel Certificates...........................................  45

11.   Miscellaneous.........................................................  46
      11.1  Recording of Lease..............................................  46
      11.2  Notices.........................................................  46
      11.3  Successors and Limitation on Liability
            of the Landlord.................................................  47

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      11.4  Waivers by the Landlord.........................................  47
      11.5  Acceptance of Partial Payments of Rent..........................  48
      11.6  Interpretation and Partial Invalidity...........................  48
      11.7  Quiet Enjoyment.................................................  48
      11.8  Brokerage.......................................................  49
      11.9  Surrender of Premises and Holding Over .........................  49
      11.10 Landlord's Lien.................................................  50
      11.11 Right of First Offer............................................  51

EXHIBIT A:     BASIC LEASE TERMS
EXHIBIT A-1:   FLOOR PLAN OF THE PREMISES
EXHIBIT B:     STANDARD SERVICES
EXHIBIT C:     RULES AND REGULATIONS
EXHIBIT D:     TENANT'S INITIAL IMPROVEMENTS
EXHIBIT D-1:   TENANT'S PERSONAL PROPERTY
EXHIBIT D-2:   SECURED PROPERTY
EXHIBIT E:     CUSTODIAL SERVICES

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                                      LEASE

1. Recitals and Definitions

      1.1 Recitals. This Lease (this "Lease") is entered into as of April ___,
1994, by and between The Charles Stark Draper Laboratory, Inc. (the "Landlord"),
and Pharmaceutical Peptides, Inc. (the "Tenant").

      In consideration of the mutual covenants herein set forth, the Landlord
and the Tenant do hereby agree to the terms and conditions set forth in this
Lease.

      1.2 Definitions. The following Terms, have the meanings indicated or
referred to below.

      "Additional Rent" means all charges payable by the Tenant pursuant to this
Lease other than Annual Fixed Rent, including without implied limitation; the
Tenant's Tax Expense Allocable to the Premises as provided in Section 3.2; the
Tenant's Operating Expenses Allocable to the Premises in accordance with Section
3.3; amounts payable for special services pursuant to Section 3.5; the
Landlord's share of any sublease or assignment proceeds pursuant to Section 6.8.

      "Annual Fixed Rent" - See Exhibit A, and Sections 2.5 and 3.1.

      "Building" means The Hill Building located at 1 Hampshire Street,
Cambridge, Massachusetts in which the Premises are located.

      "Commencement Date" - See Exhibit A.

      "Common Building Areas" means those portions of the Building which are not
part of the Premises and to which the Tenant has appurtenant rights pursuant to
Section 2.2.

      "External Causes" means collectively, (i) Acts of God, war, civil
commotion, fire, flood or other casualty, strikes or other extraordinary labor
difficulties, shortages of labor or materials or equipment in the ordinary
course of trade, government order or regulations or other cause not reasonably
within the Landlord's control and not due to the fault or neglect of the
Landlord, and (ii)
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any act, failure to act or neglect of the Tenant or the Tenant's servants,
agents, employees, licensees or any person claiming by, through or under the
Tenant, which in either case causes delays encountered by the Landlord in the
performance of any act required to be performed by the Landlord under this Lease
which are reasonably attributable thereto.

      "Land" means the parcel of land owned by Landlord upon which the Building
is located.

      "Landlord's Original Address" - See Exhibit A.

      "Lease Year" means each period of one year during the Term commencing on
the Rent Commencement Date or on any anniversary thereof.

      "Permitted Uses" - See Exhibit A.

      "Premises" means that portion of the Building which the Tenant is leasing
at any given time pursuant to the provisions of this Lease. See Exhibit A and
Section 2.1.

      "Property" means the Land and the Building.

      "Tenant's Initial Improvements Monthly Amortization Amount" means the
quotient of (i) the unamortized cost of Tenant's Initial Improvements amortized
on a straight line basis over the Term at a rate of seven percent (7%) per
annum, divided by (ii) the number of months remaining in the unexpired Term
(including any partial month).

      "Tenant's Original Address" - See Exhibit A.

      "Term" - See Exhibit A.

2. Premises and Term

      2.1 Premises. The Landlord hereby leases to the Tenant, and the Tenant
hereby leases from the Landlord, for the Term, the Premises. The Premises shall
exclude the entry and main lobby of the Building, first floor elevator lobby,
the common stairways and stairwells, elevators and elevator wells, sprinklers,
mechanical rooms, loading and receiving areas, electric and telephone closets,
janitor closets, and pipes, ducts, conduits, wires and appurtenant fixtures and
equipment

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serving exclusively or in common other parts of the Building. If the Premises at
any time includes less than the entire rentable floor area of any floor of the
Building, the Premises shall also exclude the common corridors, vestibules,
elevator lobby and toilets located on such floor. The Tenant acknowledges that,
except as expressly set forth in this Lease, there have been no representations
or warranties made by or on behalf of the Landlord with respect to the Premises,
the Building or the Property or with respect to the suitability of any of them
for the conduct of the Tenant's activities. The Tenant acknowledges that the
Landlord is not obligated to provide any modifications to the Premises and that
the Tenant is taking the Premises in its "as is" condition. The taking of
possession of the Premises by the Tenant shall conclusively establish that the
Premises and the Building were at such time in satisfactory condition, order and
repair.

      2.2 Appurtenant Rights. The Tenant shall have, as appurtenant to the
Premises, the nonexclusive right to use in common with others, subject to
reasonable rules of general applicability to occupants of the Building from time
to time made by the Landlord of which the Tenant is given notice: (i) the front
and rear entries and main lobby of the Building, two designated elevators, the
common stairways, mechanical rooms, electric and telephone closets and the
pipes, sprinklers, ducts, conduits, wires and appurtenant fixtures and equipment
serving the Premises in common with others, (ii) common walkways and driveways
necessary or reasonably convenient for access to the Building, (iii) access to
loading area and freight elevator with prior notice to the Landlord and subject
to rules and regulations then in effect, and (iv) if the Premises at any time
include less than the entire rentable floor area of any floor, the common
toilets, corridors, and elevator lobby of such floor. Subject to the provisions
of Section 5.3, Tenant shall have elevator access to the Premises at all times
during the Term, provided that Landlord may limit the number of elevators to be
in operation at times other than during customary business hours for the
Building.

      2.3 Landlord's Reservations. The Landlord reserves the right from time to
time, without unreasonable interference with the Tenant's use: (i) to install,
use, maintain, repair, replace and relocate for service to the

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Premises and other parts of the Building, or either, pipes, ducts, conduits,
wires, chases, shafts, flues and appurtenant fixtures and equipment, wherever
located in the Premises or the Building, and (ii) to alter or relocate any
common facility, provided that substitutions are substantially equivalent or
better. In the event that Landlord's exercise of its rights under this Section
2.3 results in a material reduction in the usable area of the Premises, the
Annual Fixed Rent and the Rentable Floor Area of the Premises shall be adjusted
in proportion to the area of the Premises that Tenant can no longer use for the
conduct of its business; provided, however, that (i) Landlord's exercise of its
rights under this Section 2.3 shall not result in a reduction in the usable area
of the Premises in excess of one hundred (100) square feet, and (ii) the
location of any such reduction shall be subject to Tenant's reasonable approval.

      2.4 Parking. The Landlord shall provide and the Tenant shall pay for
parking privileges for use by the Tenant's employees and business invitees and
visitors in accordance with Exhibit A. The Landlord shall have the right to
designate from time to time, and to change from time to time, the location on
the Land that shall be used for the parking of the Tenant's automobiles. The
Tenant's parking privileges will be on a nonexclusive basis. The Tenant agrees
that it and all persons claiming by, through and under it, shall at all times
abide by the reasonable rules and regulations promulgated by the Landlord with
respect to the use of the parking area provided by the Landlord pursuant to this
Lease, provided that the same rules apply to all tenants of the Building.

      The Tenant shall pay to the Landlord for the Tenant's parking privileges
the monthly rent as provided in Exhibit A.

3. Rent and Other Payments

      3.1 Annual Fixed Rent. Subject to the last paragraph of this Section 3.1,
from and after the Rent Commencement Date, the Tenant shall pay, without notice
or demand, monthly installments of one-twelfth (1/12th) of the Annual Fixed Rent
in effect and applicable to the Premises in advance for each full calendar month
of the Term and of the corresponding fraction of said one-twelfth (1/12th) for
any fraction of a calendar month at

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the beginning or end of the Term. The Annual Fixed Rent applicable to the
Premises during the Term shall be as set forth in Exhibit A.

      Notwithstanding anything to the contrary set forth in Exhibit A, the
Annual Fixed Rent set forth therein is based upon the understanding that Tenant
shall not use or occupy that portion of the Premises containing approximately
9,797 square feet of Rentable Floor Area (the "Second Year Space") identified by
cross-hatching on Exhibit A-1 prior to the beginning of the second (2nd) Lease
Year. If Tenant uses or occupies the Second Year Space prior to the commencement
of the second (2nd) Lease Year, the Annual Fixed Rent in effect and applicable
to the Premises for the portion of the first (1st) Lease Year occurring from and
after the date of such use or occupancy shall be increased to the amount
applicable with respect to the second (2nd) Lease Year. Tenant shall immediately
deliver to Landlord written notice informing Landlord of Tenant's use or
occupancy of the Second Year Space. Tenant's performance of Tenant's Initial
Improvements (as hereinafter defined) in the Second Year Space, without
additional use or occupancy by Tenant, shall not be deemed "use" or "occupancy"
for purposes of determining Annual Fixed Rent pursuant to this Section 3.1.

      The Annual Fixed Rent payable hereunder shall be abated for the period
beginning on the Rent Commencement Date and ending on the date that is six (6)
months following the Rent Commencement Date (the "Rent Abatement Period").

      3.2 Real Estate Taxes. From and after the Rent Commencement Date, during
the Term, the Tenant shall pay to the Landlord, as Additional Rent, the Tenant's
Tax Expenses Allocable to the Premises (as such term is hereinafter defined), in
accordance with this Section 3.2. The terms used in this Section 3.2 are defined
as follows:

            (a) "Tax Year" means the 12-month period beginning July 1 each year
or, if the appropriate governmental tax fiscal period shall begin on any date
other than July 1, such other date.

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            (b) "The Tenant's Tax Expense Allocable to the Premises" means that
portion of the Landlord's Tax Expenses for a Tax year which bears the same
proportion thereto as the Rentable Floor Area of the Premises (from time to
time) bears to the Total Rentable Floor Area of the Building. In the event that
the Premises are improved to a standard which is higher than other portions of
the Property, the Tenant's Tax Expense allocable to the Premises shall include
such portion of the Real Estate Taxes on the Property with respect to any Tax
Year as is appropriate so that the Tenant bears the portion of the Real Estate
Taxes which are properly allocable to the Premises, as reasonably determined by
Landlord based on information with respect to the assessment process made
available by the assessing authorities; provided, however, that Landlord shall
make a similar allocation of Real Estate Taxes with regard to other tenants
whose premises are improved to a standard which is higher than other portions of
the Property so that Tenant is not allocated any portion of such Real Estate
Taxes.

            (c) "The Landlord's Tax Expenses" with respect to any Tax Year means
the aggregate Real Estate Taxes on the Property with respect to that Tax Year,
reduced by any abatement receipts with respect to that Tax Year.

            (d) "Real Estate Taxes" means all taxes and special assessments of
every kind and nature assessed by any governmental authority on the applicable
property and reasonable expenses of any proceedings for abatement of such taxes
including appeals thereof. The amount of special taxes or special assessments to
be included shall be limited to the amount of the installment (plus any interest
thereon) of such special tax or special assessment (which shall be payable over
the longest period permitted by law) required to be paid during the Tax Year in
respect of which such taxes are being determined. There shall be excluded from
such taxes all income, estate, succession, inheritance, excess profit, franchise
and transfer taxes; provided, however, that if at any time during the Term the
present system of ad valorem taxation of real property shall be changed so that
in lieu of the whole or any part of the ad valorem tax on real property, there
shall be assessed on the Landlord a capital levy or other tax on the gross rents
received with respect to the Property, or a Federal, State, Coun-

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ty, Municipal, or other local income, franchise, excise or similar tax,
assessment, levy or charge (distinct from any now in effect) based, in whole or
in part, upon any such gross rents, then any and all of such taxes, assessments,
levies or charges, to the extent so based, shall be deemed to be included within
the term "Real Estate Taxes."

      Payments by the Tenant on account of the Tenant's Tax Expenses Allocable
to the Premises shall be made monthly at the time and in the fashion herein
provided for the payment of Annual Fixed Rent and shall be in an amount equal to
one-twelfth (1/12) of the Tenant's Tax Expenses Allocable to the Premises for
the current Tax Year as reasonably estimated by the Landlord.

      Not later than ninety (90) days after the Landlord's Tax Expenses are
determinable for the first Tax Year of the Term or fraction thereof and for each
succeeding Tax Year or fraction thereof during the Term, the Landlord shall
render the Tenant a statement in reasonable detail showing for the preceding
year or fraction thereof, as the case may be, real estate taxes on the Property,
and any abatements or refunds of such taxes, together with copies of the
applicable tax bills. Expenses incurred in obtaining any tax abatement or refund
may be charged against such tax abatement or refund before the adjustments are
made for the Tax Year. If at the time such statement is rendered it is
determined with respect to any Tax Year, that the Tenant has paid (i) less than
the Tenant's Tax Expenses Allocable to the Premises or (ii) more than the
Tenant's Tax Expenses Allocable to the Premises, then, in the case of (i) the
Tenant shall pay to the Landlord, as Additional Rent, within thirty (30) days of
such statement the amount of such underpayment and, in the case of (ii) the
Landlord shall credit the amount of such overpayment against the monthly
installments of the Tenant's Tax Expenses Allocable to the Premises and the
Annual Fixed Rent next thereafter coming due (or refund such overpayment if the
Term has expired and the Tenant has no further obligation to the Landlord).

      To the extent that real estate taxes shall be payable to the taxing
authority in installments with respect to periods less than a Tax Year, the
statement to be furnished by the Landlord shall be rendered and payments

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made on account of such installments. Notwithstanding the foregoing provisions,
no decrease in Landlord's Tax Expenses with respect to any Tax Year shall result
in a reduction of the amount otherwise payable by Tenant if and to the extent
said decrease is attributable to vacancies in the Building, rather than to a
reduction in the assessed value of the Property as a whole or a reduction in the
tax rate. Landlord shall, upon Tenant's request therefor, provide Tenant with
copies of all applicable tax bills, statements, records and the like, as well as
copies of Landlord's calculations and all other relevant information.

      3.3 Operating Expenses. From and after the Rent Commencement Date, during
the Term the Tenant shall pay to the Landlord, as Additional Rent, the Tenant's
Operating Expenses Allocable to the Premises, as hereinafter defined, in
accordance with this Section 3.3. The terms used in this Section 3.3 are defined
as follows:

            (a) "The Tenant's Operating Expenses Allocable to the Premises"
means that portion of the Operating Expenses for the Property which bears the
same proportion thereto as the Rentable Floor Area of the Premises (from time to
time) bears to the Total Rentable Floor Area of the Building.

            (b) "Operating Expenses for the Property" means Landlord's cost of
operating, cleaning, maintaining and repairing the Property, the parking areas
for tenants in the Building and the roads, driveways and walkways for providing
access to the Building and such parking areas and shall include without
limitation, the cost of services on Exhibit B except as expressly excluded
hereunder, the cost of custodial services on Exhibit E, premiums for property,
liability and such other insurance as Landlord may carry with respect to the
Property; the amount of any commercially reasonable deductible from any
insurance claim of the Landlord; compensation and all fringe benefits, worker's
compensation insurance premiums and payroll taxes paid to, for or with respect
to all persons directly engaged in the operating, maintaining or cleaning of the
Property and such parking facilities at or below the level of building manager;
cost of steam, water, sewer, gas, oil, electricity, telephone and other utility
charges (excluding such utility charges either separately metered or separately
chargeable to tenants

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for additional or special services); cost of providing HVAC; cost of building
and cleaning supplies; rental costs for equipment used in the operating,
cleaning, maintaining or repairing of the Property, or the applicable fair
market rental charges in the case of equipment owned by the Landlord, provided
that (i) if such equipment is also used at locations other than the Property, an
appropriate allocation of fair market rental charges is made, and (ii) Landlord
shall not recover from tenants of the Property an amount in excess of Landlord's
cost to purchase such equipment, which cost shall be amortized in accordance
with generally accepted accounting principles, together with interest on the
unamortized balance at the base lending rate announced by a major commercial
bank designated by the Landlord; cost of cleaning; cost of maintenance, repairs
and replacements; cost of snow removal; cost of landscape maintenance; security
services; payments under service contracts with independent contracts; the cost
of any capital improvement made for the purpose of reducing operating expenses
or to comply with applicable law, which cost shall be amortized in accordance
with generally accepted accounting principles, together with interest on the
unamortized balance at the base lending rate announced by a major commercial
bank designated by the Landlord, provided that the cost of any such improvements
made for the purpose of reducing operating expenses includable as Operating
Expenses for the Property in any given year shall be limited to the extent of
Landlord's reasonable estimate of the savings realized in such year; and all
other reasonable and necessary expenses paid in connection with the operation,
cleaning, maintenance and repair of the Property. Any of the Operating Expenses
for the Property that vary with occupancy and that are attributable to any part
of the Term will be adjusted by Landlord to the amount that Landlord reasonably
believes they would have been if the Building had been fully occupied. Operating
Expenses for the Property shall not include the following: the Landlord's Tax
Expense; cost of repairs or replacements (i) resulting from eminent domain
takings, (ii) to the extent reimbursed by insurance, or (iii) required, above
and beyond ordinary periodic maintenance, to maintain in serviceable condition
the major structural elements of the Building, including the roof, exterior
walls and floor slabs; replacement or contingency reserves; the cost of capital
improvements (other than as specifically provided for above); payment of any
debt obligations

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(other than as specifically provided for above); legal and other professional
fees for matters not relating to the normal administration and operation of the
Property; promotional, advertising, public relations or brokerage fees and
commissions paid in connection with services rendered for securing or renewing
leases; security services; transfer, gains, franchise, inheritance, estate and
income taxes imposed upon Landlord; the cost of installations and decorations
incurred in connection with preparing space for tenants, and any other
contribution by Landlord to the cost of tenant improvements; salaries, fringe
benefits, and other compensation of Landlord's personnel above the grade of
building manager; costs for which Landlord receives compensation through the
proceeds of insurance; ground rent, if any, or any other payments under any
superior lease; costs of furnishing services to any individual tenant of the
Building to the extent the same exceeds the services provided to Tenant
hereunder without additional charge to Tenant; costs incurred with respect to a
sale of all or any portion of the Property; advertising and promotional
expenses; financing and refinancing costs (other than as a component of the
amortization of certain capital expenses as specifically provided for above);
amounts otherwise includable in Operating Expenses for the Property but
reimbursed to Landlord directly by Tenant or other tenants; costs and expenses
paid to a corporation, entity or person related to Landlord to the extent that
such costs and expenses exceed the commercially competitive costs and expenses
for similar materials and services that would be charged in the absence of such
relationship; lease takeover costs incurred by Landlord in connection with
leases in the Building; to the extent that any costs includable in Operating
Expenses for the Property are incurred with respect to the Property and other
locations (including, without limitation, salaries, fringe benefits and other
compensation of Landlord's personnel who provide services to both the Property
and other locations), the reasonable percentage thereof which is properly
allocable to such other locations, the cost of any judgment, settlement or
arbitration award resulting from any liability of Landlord (other than a
liability or amounts otherwise includable in Operating Expenses for the Property
hereunder); costs relating to withdrawal, liability or unfunded pension
liability under the Multi-Employer Pension Plan

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Act or similar law; the cost of installing, operating and maintaining any
specialty facility (such as an observatory, broadcasting facility, luncheon
club, athletic or recreational club, cafeteria or dining facility); any interest
or penalty charges incurred by Landlord due to the violation of any law, except
to the extent caused by the default of Tenant hereunder; any compensation paid
to clerks, attendants or other persons in commercial concession operated by
Landlord; costs for acquiring or renting works of fine, investment grade
sculpture, paintings or other objects of art, provided that non-investment grade
objects of art purchase primarily to decorate the Property and costs of
maintaining any art shall be included in Operating Expenses for the Property.

Nothing contained in this Section 3.3 shall permit Landlord to include duplicate
charges in Operation Expenses. Payments by the Tenants on account of the
Tenant's Operating Expenses Charge shall be made monthly at the time and in the
fashion herein provided for the payment of Annual Fixed Rent. The amount so to
be paid to the Landlord shall be an amount from time to time reasonably
estimated by the Landlord to be sufficient to aggregate a sum equal to the
Tenant's Operating Expenses Charge for each calendar year; provided that
Landlord shall deliver to Tenant notice of such estimated amount accompanied by
a statement showing Landlord's estimated expenses.

      Not later than ninety (90) days after the end of each calendar year or
fraction thereof during the Term or fraction thereof at the end of the Term, the
Landlord shall render the Tenant a statement in reasonable detail and according
to usual accounting practices certified by a representative of the Landlord,
showing for the preceding calendar year or fraction thereof, as the case may be,
the Operating Expenses for the Property and the Tenant's Operating Expenses
Allocable to the Premises. Said statement to be rendered to the Tenant also
shall show for the preceding calendar year or fraction thereof, as the case may
be, the amounts of Operating Expenses already paid by the Tenant. If at the time
such statement is rendered it is determined with resect to any calendar year,
that the Tenant has paid (i) less than the Tenant's Operating Expenses Allocable
to the Premises or (ii) more than the Tenant's Operating Expenses Allocable to
the Premises, then, in the case of (i) the Tenant shall pay to the Landlord, as
Additional Rent, within thirty (30)

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days of such statement the amounts of such underpayment and, in the case of (ii)
the Landlord shall credit the amount of such overpayment against the monthly
installments of the Tenant's Operating Expenses Allocable to the Premises and
the Annual Fixed Rent next thereafter coming due (or refund such overpayment if
the Term has expired and the Tenant has no further obligation to the Landlord).

      3.4 Inspection and Audit. Upon not less than fifteen (15) days prior
notice to Landlord, but not more frequently than once each calendar year, Tenant
shall have the right to inspect and/or audit Landlord's books and records with
respect to any of the charges of Additional Rent, including the Real Estate
Taxes and the Operating Expenses for the Property, with respect to the
immediately preceding calendar year. In the event the inspection or audit
reveals no overstatement in the charges paid by Tenant, Tenant shall reimburse
Landlord for any out-of-pocket costs which Landlord incurs in connection with
obtaining the services of professionals to respond to Tenant's requests for
information and/or explanation in connection with such inspection or audit,
within thirty (30) days after notice form Landlord. The inspection or audit
shall be performed at Landlord's office. In the event Tenant, after completion
of such audit or inspection, shall dispute the correctness of Landlord's Annual
Statement of Operating Expenses for the Property in accordance with the terms of
this Lease, Tenant shall notify Landlord of such dispute on or before the date
which is twelve (12) months following the last day of the calendar year with
respect to which such expenses relate, specifying the particular respects in
which such statement is allegedly incorrect. In the event the inspection or
audit reveals that Tenant has paid more than Tenant's Tax Expense Allocable to
the Premises or Tenant's Operating Expenses allocable to the Premises, Landlord
shall credit the amount of such over-payment against the monthly installments of
Rent next thereafter coming due (or refund such overpayment if the Term has
expired and Tenant has no further obligation to Landlord).

      3.5 Electricity. Electrical energy to the extent required for lighting and
electrical facilities, equipment, machinery, fixtures and appliances
substantially equivalent to the lighting and electrical facilities,

                                       12
<PAGE>

equipment, machinery, fixtures and appliances of Landlord in the space in the
Building occupied by Landlord, and the space occupied by Landlord in neighboring
buildings, shall be provided to the Premises and Tenant shall pay, as Additional
Rent, the share of electrical energy charges paid by Landlord to the electric
utility which is allocable to the Premises. The electric energy required to
operate the air-handling units serving Tenants laboratories, to be constructed
as part of Tenant's Initial Work (including the exhaust system and system for
re-heat of make-up air), and any other mechanical equipment which may be
installed in the Premises by Tenant from time to time which consumes
significantly more electric energy than the mechanical equipment currently
contained therein, shall be separately check-metered and the cost of such
electric energy shall be payable by Tenant to Landlord as Additional Rent. In
the event that, after the date hereof, Landlord undertakes alterations or
additions to any space occupied by Landlord which includes the installation of
mechanical equipment which consumes significantly more electric energy than the
mechanical equipment currently contained therein, Landlord shall reasonably
allocate the increased electrical energy costs associated with such equipment
and exclude such cost from the aggregate energy expense proportionately
allocated to Tenant; provided, however, that the provisions of this sentence
shall not apply to any equipment installed as a replacement for existing
equipment.

      3.6 Other Utility Charges. During the Term, the Tenant shall pay directly
to the provider of the service, all separately metered charges for steam, heat,
gas, electricity, fuel and other services and utilities furnished to the
Premises.

      3.7 Above-Standard Services. If the Tenant requests and the Landlord
elects to provide any services to the Tenant in addition to those described in
Exhibit B, the Tenant shall pay to the Landlord, as Additional Rent, the amount
billed by Landlord for such services at Landlord's standard rates as from time
to time in effect. If Tenant has requested that such services be provided on a
regular basis, Tenant shall, if requested by Landlord, pay for such services at
the time and in the fashion in which Annual Fixed Rent under this Lease is
payable. Otherwise, Tenant shall pay for such additional services within thirty
(30) days after receipt of an invoice from

                                       13
<PAGE>

Landlord. Landlord shall have the right, at its election, to survey Tenant's
electricity usage in the Premises and/or install a check meter therein, in
either case at Tenant's expense, for purposes of monitoring above-standard
electricity usage. Tenant shall pay for such work within thirty (30) days after
receipt of an invoice from Landlord.

      3.8 No Offsets. Annual Fixed Rent and Additional Rent shall be paid by the
Tenant without offset, abatement or deduction.

      3.9 Security Services. During the Term and any extension thereof, the
Tenant shall pay Six Thousand Six Hundred Dollars ($6,600.00) per year for the
Security Services described on Exhibit B.

      3.10 Net Lease. It is understood and agreed that this Lease is a Net Lease
and that the Annual Fixed Rent is absolutely net to Landlord, accepting only
Landlord's obligation to pay any debt service or ground rent on the Property, to
provide Landlord's services, and to pay the real estate taxes and operating
expenses which Tenant is not required to pay under this Lease.

4. Alterations.

      4.1 Consent Required for Tenant's Alterations. The Tenant shall not make
alterations or additions to the Premises except in accordance with the building
standards from time to time in effect, with construction rules and regulations
from time to time promulgated by Landlord and applicable to Tenants in the
Building, and with plans and specifications therefor first approved by the
Landlord, which approval shall not be withheld unreasonably; provided, however,
that such alterations do not change the character of the Premises as laboratory
space, subject to the provisions of Section 11.10 with respect to Secured
Property (as hereinafter defined). The Landlord shall not be deemed unreasonable
for withholding approval of any alterations or additions which (i) might
adversely affect any structural element of the Building, (ii) involves or might
affect the roof of the Building (subject, however, to Section 4.7), any area or
element outside of the Premises, or any facility serving any area of the
Building outside of the Premises or any publicly accessible major interior
features of the Building, or (iii)

                                       14
<PAGE>

will require unusual expense to readapt the Premises to normal use unless the
Tenant first gives assurance acceptable to the Landlord that such readaptation
will be made prior to such termination without expense to the Landlord, in each
case as reasonably determined by the Landlord. Notwithstanding the foregoing,
Tenant may, without the prior written consent of Landlord, install or replace
wall coverings or floor coverings and otherwise decorate the Premises.

      4.2 Ownership of Alternations. All alterations and additions ("Leasehold
Improvements") shall be part of the Building and owned by the Landlord, and
unless at the time of granting its consent therefor the Landlord shall specify
that the same must be removed, such Leasehold Improvements may not be removed
from the Premises without Landlord's written consent, which may be withheld in
Landlord's sole discretion. Nothing in the preceding sentence is intended to
derogate from Tenant's right to make alterations to the Premises as contemplated
under Section 4.1. The movable equipment and furnishings not attached to the
Premises, which are specified on Exhibit D-1, shall remain the property of the
Tenant and shall be removed by the Tenant upon termination or expiration of this
Lease. Tenant shall, in connection with removing any Leasehold Improvements or
personal property from the Premises which Tenant is permitted or required to
remove, repair any damage or injury caused by such removal.

      4.3 Construction Requirements for Alterations. All construction work by
the Tenant shall be done in a good and workmanlike manner employing only good
materials and in compliance with all applicable laws and all lawful ordinances,
regulations and orders of Governmental authority and insurers of the Building.
The Landlord or Landlord's authorized agent may (but without any implied
obligation to do so) inspect the work of the Tenant at reasonable times and
shall give notice of observed defects. All of the Tenant's alterations and
additions and installation of furnishings shall be coordinated with any work
being performed by the Landlord and in such manner as to maintain harmonious
labor relations and not to damage the Building or interfere with Building
construction or operation and, except for installation of furnishings, shall be
performed by contractors or workmen first approved by the Landlord, which
approval the Landlord agrees not to unreasonably withhold or delay. The

                                       15
<PAGE>

Tenant, before starting any work, shall receive and comply with Landlord's
construction rules and regulations and shall cause Tenant's contractors to
comply therewith, shall secure all licenses and permits necessary therefor and
shall deliver to the Landlord a statement of the names of all its contractors
and subcontractors and the estimated cost of all labor and material to be
furnished by them and, in the event the cost of such alterations (excluding
decorations) shall exceed two hundred fifty thousand dollars ($250,000.00),
security satisfactory to the Landlord protecting the Landlord against liens
arising out of the furnishing of such labor and material; and cause each
contractor to carry worker's compensation insurance in statutory amounts
covering all the contractors' and subcontractors' employees and comprehensive
general public liability insurance with such limits as the Landlord may require
reasonably, but in no event less than $1,000,000 (individual)/$3,000,000
(occurrence) or in such other amounts as Landlord may reasonably require
covering personal injury and death and property damage (all such insurance to be
written in companies approved reasonably by the Landlord and insuring the
Landlord, such individuals and entities affiliated with the Landlord as the
Landlord may designate, and the Tenant as well as the contractors and to contain
a requirement for at least thirty (30) days' notice to the Landlord prior to
cancellation, nonrenewal or material change), and to deliver to the Landlord
certificates of all such insurance.

      4.4 Payment for Tenant Alterations. The Tenant agrees to pay promptly when
due the entire cost of any work done on the Premises by the Tenant, its agents,
employees or independent contractors, and not to cause or permit any liens for
labor or materials performed or furnished in connection therewith to attach to
the Premises or the Property and promptly to discharge any such liens which may
so attach. If any such lien shall be filed against the Premises or the Property
and the Tenant shall fail to cause such lien to be discharged within thirty (30)
days after Tenant has notice of the filing thereof, the Landlord may cause such
lien to be discharged by payment, bond or otherwise, without investigation as to
the validity thereof or as to any offsets or defenses which the Tenant may have
with respect to the amount claimed; provided, however, that in the event
Landlord is in the process of selling, or obtaining a

                                       16
<PAGE>

loan secured in whole or in part by, the Property, Tenant shall be obligated to
cause such lien to be discharged within twenty (20) days after Tenant has notice
thereof. The Tenant shall reimburse the Landlord, as additional rent, for any
cost so incurred and shall indemnify and hold harmless the Landlord from and
against any and all claims, costs, damages, liabilities and expenses (including
attorneys' fees) which may be incurred or suffered by the Landlord by reason of
any such lien or its discharge.

      4.5 Tenant's Initial Improvements. (a) Tenant shall, at Tenant's sole cost
and expense, make certain alterations and additions to the Premises, as more
particularly described in the scope of work attached as Exhibit D ("Tenant's
Initial Improvements"). Notwithstanding anything to the contrary contained
herein, Tenant's Initial Improvement shall include the construction of two (2)
mechanical and electrical rooms with all mechanical and electrical components
(including, without limitation, fans and air handling units) required for
Tenant's contemplated use of the Premises (including the Second Year Space);
provided, however, that the VAV boxes and other distribution and control
components necessary to distribute service to the Second Year Space need not be
included in Tenant's Initial Improvements. Tenant's Initial Improvements shall
be performed, in all respects, in accordance with Article 4 hereof. Tenant
agrees that Tenant's Initial Improvements will be performed in a manner so as to
minimize the disturbance to the occupants of other parts of the Building;
provided, however, that Tenant shall not be required to perform such work on an
overtime basis unless such work is to be performed in space occupied by another
tenant of the Building or Landlord, in which event such work shall be performed
on an overtime basis unless such other tenant or Landlord agrees with Tenant in
writing that Tenant may perform the required work during ordinary business
hours. Tenant shall use commercially reasonable efforts to complete Tenant's
Initial Improvements on or before September 15, 1994.

            It is understood that of the services to be furnished by Landlord
referred to in Section 5.1 and Exhibit B hereof, Landlord shall not furnish any
cleaning services until Tenant commences occupancy of the Premises (exclusive of
the Second Year Space) for the conduct of its business. Tenant shall be
responsible for removal of

                                       17
<PAGE>

Tenant's refuse and rubbish during the period that Tenant's Initial Improvements
are in progress in the Premises.

            (b) Tenant, at Tenant's expense, shall cause an architect approved
in writing by Landlord, which approval Landlord shall not unreasonably withhold
(the "Architect"), to prepare a set of plans, specifications and working
drawings (the "Plans and Specifications") for Tenant's Initial Improvements. As
used herein, the term "Plans and Specifications" shall include the MEP Plans and
Specifications (as hereinafter defined). Tenant shall also obtain Landlord's
prior written approval of any engineer who prepares engineering plans and
specifications comprising a portion of the Plans and Specifications, which
approval shall not be unreasonably withheld.

      Landlord and Tenant hereby acknowledge that Tenant shall perform Tenant's
Initial Improvements on a so-called "fast-track" basis, whereby certain items of
construction shall be commenced before all Plans and Specifications have been
finalized. Notwithstanding the foregoing, the Plans and Specifications for the
mechanical, electrical and plumbing components of Tenant's Initial Improvements
(the "MEP Plans and Specifications") shall be submitted by Tenant to Landlord on
or prior to the date occurring forty-five (45) days form the date hereof for
Landlord's review. The MEP Plans and Specifications must be approved by Landlord
in writing prior to Tenant's commencement of Tenant's Initial Improvements
except for any demolition of the existing Leasehold Improvements. After the MEP
Plans and Specifications have been approved by Landlord, Tenant will, during the
course of construction, furnish Landlord with all other Plans and Specifications
as the same are prepared.

      Tenant shall reimburse Landlord, within ten (10) days of demand, for any
out-of-pocket costs and expenses incurred by Landlord in connection with
Landlord's review of the Plans and Specifications. Tenants shall make such
changes to the Plans and Specifications as Landlord reasonably requires and
Tenant shall not commence the performance of any portion of Tenant's Initial
Improvements prior to obtaining Landlord's prior written approval of the Plans
and Specifications relating thereto, which shall not be unreasonably withheld.
Landlord's failure to either approve, reject or request additional

                                       18
<PAGE>

information regarding the Plans and Specification submitted by Tenant within
fifteen (15) days from Landlord's receipt thereof shall be deemed to be
Landlord's approval of said Plans and Specification. Any rejection by Landlord
shall be in writing, shall specify the reasons for such rejection and shall
outline the required modifications thereto which would render said Plans and
Specifications acceptable. After Landlord has approved Plans and Specifications,
Tenant shall promptly and diligently perform the Tenant's Initial Improvements
in accordance with such approved Plans and Specifications, and pursue said work
to completion. Tenant shall thereafter resubmit any modifications of or
additions to the approved Plans and Specifications for Landlord's approval,
which approval shall not be unreasonably withheld.

            (c) Landlord shall not be deemed unreasonable for withholding
approval of any portion of the Plans and Specifications for Tenant's Initial
Improvements which (i) might materially adversely affect any structural element
of the Building, or (ii) involves or might affect the roof of the Building
(subject, however, to Section 4.7), any area or element outside of the Premises,
or any facility serving any area of the Building outside of the Premises or any
publicly accessible major interior features of the Building. Notwithstanding the
foregoing, Landlord acknowledges that nothing described in the scope of the work
set forth in Exhibit D presents grounds for Landlord's withholding approval on
the basis of any of clauses (i) or (ii) above, provided the same conforms to a
typical first-class laboratory build-out, consistent with similar facilities in
the metropolitan Boston area.

      4.6 Security for Performance of Tenant's Initial Improvements.

            (a) Prior to commencing the performance of Tenant's Initial
Improvements, or any demolition of the existing Leasehold Improvements, Tenant
shall deposit with Landlord as security for Tenant's timely performance and
completion of Tenant's Initial Improvements, a sum of money equal to the product
of (i) Eighty Dollars ($80.00), multiplied by (ii) the number of rentable square
feet of the Premises (in no event less than 15,000 rentable square feet) which
shall be improved by Tenant in connection with Tenant's Initial Improvements
(the

                                       19
<PAGE>

"Construction Security Deposit"). The Construction Security Deposit shall be
held by Landlord and disbursed or used in accordance with this Section 4.6. In
the event that either any Budget (as defined below) estimates the cost to
complete Tenant's Initial Improvements to be greater than the amount of the
Construction Security Deposit then held by Landlord, Tenant shall deposit with
Landlord additional sums such that the undisbursed amount of the Construction
Security Deposit will be sufficient, when disbursed to Tenant, to pay all
estimated unpaid costs required to complete Tenant's Initial Improvements,
including the payment of all so-called "soft" costs.

            (b) Landlord shall invest the Construction Security Deposit in the
"Bank Account." In this Lease, the term "Bank Account" means a "money-market"
rate account with Bay Bank. Landlord shall have no responsibility for the rate
or amount of any interest earned on the Construction Security Deposit or for the
preservation of the principal of the Construction Security Deposit. All interest
earned on the Construction Security Deposit shall be deemed to be part of the
Construction Security Deposit and shall be held and/or disbursed in the same
manner as the Construction Security Deposit.

            (c) Once Tenant has deposited the Construction Security Deposit with
Landlord, Tenant shall be permitted to commence with the demolition work
required to prepare the Premises for Tenant's Initial Improvements. Tenant shall
not, however, commence any construction of Tenant's Initial Improvements, and
Landlord shall not be required to disburse any portion of the Construction
Security Deposit, unless and until Landlord has first received the following
items:

            (i) A detailed preliminary budget prepared by Architect representing
      Architect's good faith estimate, based on Architect's best professional
      judgement, specifying the anticipated costs of construction, fixturing and
      equipping Tenant's Initial Improvements, as known to Architect at the time
      (a "Budget"), accompanied by a written certification from an officer of
      Tenant that, in connection with Architect's preparation of such Budget,
      Tenant has provided Architect with all the relevant details of Tenant's
      Initial Improvements known to Tenant as of the date of such Budget;

                                       20
<PAGE>

            (ii) A detailed preliminary construction schedule (the "Schedule")
      for Tenant's Initial Improvements prepared by Architect, representing
      Architect's good faith estimate, based on Architect's best professional
      judgement, showing the estimated periods of commencement and completion of
      construction of Tenant's Initial Improvements and projected Requisitions
      (as hereinafter defined), as known to Architect at the time, accompanied
      by a written certification from an officer of Tenant that, in connection
      with Architect's preparation of such Schedule, Tenant has provided
      Architect with all the relevant details of Tenant's Initial Improvements
      known to Tenant as of the date of such schedule;

            (iii) A fully-executed contract between Tenant and the Architect, to
      perform architectural services in connection with Tenant's Initial
      Improvements, which contract contains Architect's agreement to perform
      such services for Landlord subsequent to an Event of Default and
      termination of the Lease upon the same terms and conditions of Architect's
      agreement with Tenant;

            (iv) A fully-executed contract between Tenant and Tenant's general
      contractor who shall be performing Tenant's Initial Improvements on
      Tenant's behalf (the "General Contractor"), to perform contracting
      services in connection with Tenant's Initial Improvements, which contract
      contains the General Contractor's agreement to perform such services for
      Landlord subsequent to an Event of Default and termination of the Lease
      upon the same terms and conditions of the General Contractor's agreement
      with Tenant;

            (v) The approved MEP Plans and Specifications; and

            (vi) The building permit and all other permits and approvals
      necessary for construction of Tenant's Initial Improvements.

            (d) As long as Landlord has not terminated the Lease after an Event
of Default, Landlord shall make disbursements the Construction Security Deposit
to the

                                       21
<PAGE>

Architect, the General Contractor, any engineer, contractor, subcontractor, or
supplier who has performed work or supplied materials in connection with
Tenant's Initial Improvements upon written Requisition to Landlord by Tenant
directing such disbursement, in installments as Tenant's Initial Improvements
progress. The amount of each installment shall be an amount equal to the actual
cost of Tenant's Initial Improvements completed and in place, less (A) retainage
in the amount of 10% of the value of labor and materials covered by the
Requisition, and (B) the aggregate amount of all sums previously disbursed to
Tenant pursuant to this Section 4.6. Disbursements hereunder shall be made
solely for the payment of expenses properly incurred in the construction of
Tenant's Initial Improvements.

            (e) All requisitions for payment of installments of the Construction
Security Deposit ("Requisitions") shall be submitted by Tenant to Landlord at
least fifteen (15) days before the date upon which the installment is desired
from Landlord accompanied by the following:

            (i) A request by Tenant to Landlord directing Landlord to pay the
      specified architect, engineer, contractor, subcontractor, or supplier the
      amount(s) provided therein;

            (ii) Copies of invoices and other documents, including a cost
      breakdown, to support the amount requested in the Requisition;

            (iii) Partial or final lien waivers from any architect, engineer,
      contractor, subcontractor, or supplier, or receipts from the same, and any
      applicable bills of sale, for work or supplies that were the subject of
      any previous Requisition; and

            (iv) A revised Budget, dated as of the date of such Requisition,
      prepared by Architect, representing Architect's good faith estimate, based
      on Architect's best professional judgment, specifying the anticipated
      remaining costs of constructing, fixing and equipping Tenant's Initial
      Improvements, as known to Architect at the time, accompanied by a written
      certification from an officer of Tenant that, in connection with
      Architect's preparation of

                                       22
<PAGE>

      such revised Budget, Tenant has provided Architect with all of the
      relevant details of Tenant's Initial Improvements known to Tenant as of
      the date of such revised Budget.

Any request for any disbursement hereunder shall automatically constitute a
representation by Tenant that all conditions contained herein are then
satisfied, that, to the best of Tenant's knowledge, all Tenant's Initial
Improvements represented by the Requisition have been satisfactory completed in
accordance with Plans and Specifications approved by Landlord, that all checks
for amounts previously delivered by Landlord to Tenant have been paid to the
applicable architect, engineer, contractor, subcontractor, or supplier, and that
the undisbursed amount of the Construction Security Deposit will be sufficient,
when disbursed to Tenant, to pay all unpaid costs required to complete Tenant's
Initial Improvements, including the payment of all non-construction costs, based
upon the most recent revised Budget.

            (f) Landlord shall not be required to disburse, and shall be
entitled to withhold, the final installment of the Construction Security
Deposit, representing the ten percent (10%) retainage provided for in subsection
(d), unless and until: (i) Tenant's Initial Improvements are completed to the
satisfaction of Landlord and Landlord receives a certificate from the Architect
that Tenant's Initial Improvements are completed; (ii) the final certificate of
occupancy has been issued by the appropriate governmental authority; (iii)
either (A) Landlord has received final lien waivers from all engineers,
architects, contractors, suppliers and subcontractors who performed services or
supplied materials in connection with Tenant's Initial Improvements, or (B) the
applicable statutory mechanic's or supplier's lien period has expired; and (iv)
Tenant has delivered to Landlord final as-built Plans and Specifications for
Tenant's Initial Improvements.

            (g) In the event Landlord has terminated the Lease after an Event of
Default, Landlord shall have the right, without notice to Tenant, to make any
disbursement in whole or in part by payment directly to any engineer, architect,
contractor, subcontractor, or supplier for the account of the Tenant or for its
own account. The execution of this Lease by Tenant shall and hereby does con-

                                       23
<PAGE>

stitute an irrevocable direction and authorization to so disburse the
Construction Security Deposit. No further direction or authorization from Tenant
shall be necessary to warrant such direct payments and all such disbursement
shall satisfy pro tanto the obligations of the Landlord as fully as if made
directly to a third party pursuant to Tenant's direction contained in a
Requisition or otherwise, regardless of the disposition thereof made by such
architect, engineer, contractor, supplier or subcontractor.

      4.7 Use of Roof. Landlord agrees that Tenant may, in connection with
Tenant's Initial Improvements, at Tenant's sole cost and expense, install on the
roof of the Building, and thereafter maintain, repair and operate one (1)
emergency generator, one (1) gas heater, one (1) chiller and exhaust vents, fans
and fan hoods (together with support structures, duct work, electrical lines and
related equipment, the "Roof Equipment"), provided and on condition that: (i)
the size and dimensions of the Roof Equipment as well as the location on the
roof for such installation shall be subject to Landlord's consent which may be
withheld in Landlord's sole discretion, exercised in good faith (provided
further that Landlord shall exercise reasonable judgment as long as the Roof
Equipment occupies no more than four hundred (400) square feet of roof space
designated by Landlord); (ii) no such equipment shall extend higher than the
parapet of the roof of the Building; (iii) the installation and position of such
Roof Equipment shall comply with all laws and legal requirements; (iv) the
installation of the Roof Equipment shall comply with all laws and legal
requirements; and (v) the Roof Equipment shall be maintained and kept in repair
by Tenant, at Tenant's sole cost and expense. Tenant covenants and agrees that
the Roof Equipment to be installed by Tenant shall not interfere with or
adversely affect any equipment, installations, lines or machinery of the
Building or any other tenant of the Building, or access thereto for maintenance,
repair or removal. Tenant shall not be obligated to pay any additional rental on
account of Tenant's use of the roof of the Building pursuant to this Section
4.7.

      For the purpose of installing, servicing or repairing the Roof Equipment,
Tenant shall have access to the roof of the Building upon making prior
reasonable request of Landlord. All access by Tenant to the roof of the

                                       24
<PAGE>

Building shall be subject to the supervision and control of Landlord and to
Landlord's reasonable safeguards relating, without limitation, to the security
and protection of the Building, the Building equipment and installations and
equipment of other tenants of the Building as may be located on the roof of the
Building, and any roof warranty that may be in effect. Landlord shall have the
right to assign an outside consultant to be present during the duration of
Tenant's access to the rooftop and Tenant shall pay the Landlord's out-of-pocket
costs therefor as Additional Rent; provided, however, that in the event Tenant
engages United Engineers for structural engineering services, Tenant shall not
be required to pay any additional charges for Landlord to hire an outside
structural engineer to review and/or supervise such structural engineering work.

      Tenant, at Tenant's sole cost and expense, agrees to promptly and
faithfully obey, observe and comply with all laws, ordinances, regulations,
requirements and rules of all duly constituted public authorities in any manner
affecting or relating to Tenant's use of the roof of the Building as to the
installation, repair, maintenance and operation of any Roof Equipment erected or
installed by Tenant pursuant to the provisions of this Section 4.7. Tenant, at
Tenant's sole cost and expense, shall secure and thereafter maintain all permits
and licenses required for the installation and operation of the Roof Equipment
erected or installed by Tenant pursuant to the provisions of this Section 4.7.

      Upon the expiration of the Term or upon the earlier termination of this
Lease in any manner, if Landlord so directs by written notice to Tenant, Tenant
shall promptly remove the Roof Equipment as designated in such notice, at
Tenant's sole cost and expense. Tenant, at Tenant's sole cost and expense, shall
promptly repair any and all damage to the roof of the Building and to any other
part of the Building caused by or resulting from the installation, maintenance
and repair, operation or removal of the Roof Equipment erected or installed by
Tenant pursuant to the provisions of this Section 4.7 and restore said affected
areas to their condition as existed prior to the installation of such equipment.

      Tenant covenants and agrees that all installations made by Tenant on the
roof of the Building or any other

                                       25
<PAGE>

part of the Building pursuant to the provisions of this Section 4.7 shall be at
the sole risk of Tenant, and neither Landlord nor Landlord's agent or employees
shall be liable for any damage or injury thereto caused in any manner, unless
the same shall result from the gross negligence or willful misconduct of
Landlord, its agents and employees.

      Tenant will, and does hereby, indemnify and save harmless Landlord from
and against any and all claims, costs, demands, expenses, fees or suits arising
out accidents, damage, injury or loss to any and all persons and property, or
either, whomsoever or whatsoever resulting from or arising in connection with
the erection, installation, maintenance and operation and repair of the Roof
Equipment, except to the extent caused by the negligence of Landlord, or its
agents or employees. If any installations are negligently performed or if
Tenant's negligent acts or omissions should revoke, negate or in any manner
impair or limit any roof warranty or guaranty obtained by Landlord, then Tenant
shall reimburse Landlord for any loss or damage sustained or costs or expenses
incurred by Landlord as a result thereof.

      Tenant shall not be permitted to assign or transfer all or any portion of
the rights granted to Tenant pursuant to this Section 4.7 unless Tenant assigns
this Lease to the party to whom such rights are assigned or transferred.

5.    Responsibility for Condition of Building and Premises.

      5.1 Maintenance of Building and Common Areas by Landlord. Except as
otherwise provided in Article 8, the Landlord shall make such repairs to the
structural elements of the Building, including the roof, exterior walls and
floor slabs as may be necessary to keep and maintain the same in serviceable
condition and maintain and make such repairs to the Common Building Areas as may
be necessary to keep them in good order, condition and repair, including without
limitation, the glass in the exterior walls of the Building, and all mechanical
systems and equipment serving the Building and not exclusively serving the
Premises. The Landlord shall further perform the services on Exhibit B hereto.
The Landlord shall in no event be responsible to the Tenant for any

                                       26
<PAGE>

condition in the Premises or the Building caused by an act or neglect of the
Tenant, or any invitee or contractor of the Tenant. Landlord's costs in
performing such services shall be reimbursed by the Tenant to the extent
provided in Section 3.3.

      5.2 Maintenance of Premises by Tenant. The Tenant shall keep neat and
clean and maintain in good order, condition and repair the Premises and every
part thereof and all Building and mechanical equipment exclusively serving the
Premises, reasonable wear and tear excepted and further excepting those repairs
for which the Landlord is responsible pursuant to Section 5.1 and damage by fire
or other casualty and as a consequence of the exercise of the power of eminent
domain and shall surrender the Premises and all alterations and additions
thereto, at the end of the Term, in such condition, first removing all goods and
effects of the Tenant and, to the extent specified by the Landlord by notice to
the Tenant, all alterations and additions made by the Tenant and repairing any
damage caused by such removal and restoring the Premises and leaving them clean
and neat. The Tenant shall not permit or commit any waste, and the Tenant shall
be responsible for the cost of repairs which may be made necessary by reason of
damages to common areas in the Building by the Tenant, or any of the contractors
or invitees of the Tenant.

      5.3 Delays in Landlord's Services. The Landlord shall not be liable to the
Tenant for any compensation or reduction of rent by reason of inconvenience or
annoyance or for loss of business arising from the necessity of the Landlord or
its agents entering the Premises for any purposes authorized in this Lease, or
for repairing the Premises or any portion of the Building. In case the Landlord
is prevented or delayed from making any repairs, alterations or improvements, or
furnishing any services or performing any other covenant or duty to be performed
on the Landlord's part, by reason of any External Cause, the Landlord shall not
be liable to the Tenant therefor, nor, except as expressly otherwise provided in
this Lease, shall the Tenant be entitled to any abatement or reduction of rent
by reason thereof, nor shall the same give rise to a claim in the Tenant's favor
that such failure constitutes actual or constructive, total or partial, eviction
from the Premises.

                                       27
<PAGE>

      The Landlord reserves the right to stop any service or utility system when
necessary by reason of accident or emergency, until necessary repairs have been
completed; provided, however, that in each instance of stoppage, the Landlord
shall exercise reasonable diligence to eliminate the cause thereof. Except in
case of emergency repairs, the Landlord will give the Tenant reasonable advance
written notice of any contemplated stoppage and will use reasonable efforts to
avoid unnecessary inconvenience to the Tenant by reason thereof. In no event
shall the Landlord have any liability to the Tenant for the unavailability of
heat, light or any utility or service to be provided by the Landlord to the
extent that such unavailability is caused by External Causes.

6. Tenant Covenants

      The Tenant covenants during the Term and for such further time as the
Tenant occupies any part of the Premises:

      6.1 Permitted Uses. The Tenant shall occupy the Premises only for the
Permitted Uses, and shall not injure or deface the Premises or the Property, nor
permit in the Premises any auction sale. The Tenant shall give written notice to
the Landlord of any materials on OSHA's right to know list or which are subject
to regulation by any other federal, state, municipal or other governmental
authority and which the Tenant intends to have present at the Premises. The
Tenant shall comply with all requirements of public authorities and of the Board
of Fire Underwriters in connection with methods of storage, use and disposal of
all such materials. The Tenant shall not permit in the Premises any nuisance, or
the emission from the Premises of any objectionable noise, odor or vibration,
nor use or devote the Premises or any part thereof for any purpose which is
contrary to law or ordinance or liable to invalidate or increase premiums
(unless Tenant pays the entire amount of such increase) for any insurance on the
Building or its contents or liable to render necessary any alteration or
addition to the Building, nor commit or permit any waste in or with respect to
the Premises. The Tenant shall not generate, store or dispose of any oil, toxic
substances, hazardous wastes, or hazardous materials (each a, "Hazardous
Material"), or permit the same in or on the Premises or any parking areas
provided for under this Lease, except in compliance

                                       28
<PAGE>

with all applicable laws relating to such Hazardous Materials. The Tenant shall
not dump, flush or in any way introduce any Hazardous Materials into septic,
sewage or other waste disposal systems serving the Building generally or any
parking areas provided for under this Lease. The Tenant will indemnify the
Landlord and its successors and assigns against all claims, loss, cost, and
expenses including attorneys' fees, incurred as a result of any contamination of
the Property with Hazardous Materials by the Tenant or Tenant's contractors,
licensees, invitees, agents, servants or employees.

      6.2 Laws and Regulations. The Tenant, at Tenant's sole cost and expense,
shall comply with all federal, state and local laws, rules, regulations,
ordinances, executive orders, Federal guidelines, and similar requirements in
effect from time to time (collectively "Laws") relating to the use, condition or
occupancy of the Premises (including, without limitation, City of Cambridge
ordinances with respect to animal experiments and hazardous waste and relating
to the Building if necessitated by Tenant's improvements or manner of use
therein. Except to the extent that compliance is Tenant's responsibility
hereunder, Landlord shall be responsible for maintaining the Building in
compliance with Laws to the extent that failure to so maintain the Building
would (i) imminently endanger persons or property, (ii) prevent access to the
Premises, or (iii) prevent Tenant from performing Tenant's Initial Improvements;
provided; however, that Tenant shall be solely responsible for maintaining the
Building in compliance with laws to the extent necessitated by Tenant's Initial
Improvements.

      6.3 Rules and Regulations. The Tenant shall not obstruct in any manner any
portion of the Property not hereby leased; shall not permit the placing of any
signs, curtains, blinds, shades, awnings, aerials or flagpoles, or the like,
visible from outside the Premises; and shall comply with all reasonable rules
and regulations of uniform application to all occupants of the Building now or
hereafter made by the Landlord, of which the Tenant has been given notice, for
the care and use of the Property. The Landlord shall not be liable to the Tenant
for the failure of other occupants of the Building to conform to any such rules
and regulations. The initial rules and regulations are set forth in Exhibit C.

                                       29
<PAGE>

      6.4 Safety Compliance. The Tenant shall keep the Premises equipped with
all safety appliances required by law or ordinance or any other regulations of
any public authority because of any non-office use made by the Tenant and to
procure all licenses and permits so required by Laws because of such use and, if
requested by the Landlord, do any work so required because of such use, it being
understood that the foregoing provisions shall not be construed to broaden in
any way the Tenant's Permitted Uses.

      6.5 Landlord's Entry. The Tenant shall permit the Landlord and its agents,
after reasonable notice except in the case of emergencies, to enter the Premises
at all reasonable hours for the purpose of inspecting or of making repairs to
the same, monitoring Tenant's compliance with the requirements and restrictions
set forth in this Lease, and for the purpose of showing the Premises to
prospective purchasers and mortgagees at all reasonable times and to prospective
tenants provided that in connection with such entry, Tenant may provide
procedures reasonably designed so as not to jeopardize Tenant's trade secrets,
proprietary technology or critical business operations.

      6.6 Floor Load. The Tenant shall not place a load upon any floor in the
Premises exceeding the floor load per square foot of area which such floor was
designed to carry and which is allowed by law; and not move any safe, vault or
other heavy equipment in, about or out of the Premises except in such manner and
at such time as the Landlord shall in each instance authorize. The Tenant's
machines and mechanical equipment shall be placed and maintained by the Tenant
at the Tenant's expense in settings sufficient to absorb or prevent vibration or
noise that may be transmitted to the Building structure or to any other space in
the Building.

      6.7 Personal Property Tax. The Tenant shall pay promptly when due all
taxes which may be imposed upon personal property (including, without
limitation, trade fixtures and equipment) in the Premises to whomever assessed.

      6.8 Assignment, Subleases or other Transfers. The Tenant shall not assign,
mortgage, pledge, hypothecate or otherwise transfer this Lease or any of
Tenant's

                                       30
<PAGE>

interest therein, or sublet (which term, without limitation, shall include
granting of concessions, licenses and the like) the whole or any part of the
Premises without, in each instance, having first received the consent of the
Landlord. However, Landlord shall not unreasonably withhold consent to a
proposed assignment of this Lease or sublease of the Premises. Any assignment or
sublease made without such consent shall be void. The Landlord shall not be
deemed to be unreasonable in withholding its consent to any proposed assignment
or subletting by the Tenant based on any of the following factors:

            (a) The business of the proposed occupant is not consistent with the
image and character which the Landlord desires to promote for the building.

            (b) The proposed assignment or subletting could adversely affect the
ability of the Landlord and its affiliates to lease space in the Building
including leasing other space to any proposed assignee or subtenant.

      Whether or not the Landlord consents to any assignment or subletting, the
Tenant named herein shall remain fully and primarily liable for the obligations
of the tenant hereunder, including, without limitation, the obligation to pay
Annual Fixed Rent and Additional Rent provided under this Lease.

      The Tenant shall give the Landlord notice of any proposed sublease or
assignment, specifying the provisions of the proposed subletting or assignment,
including (i) the name and address of the proposed subtenant or assignee, (ii) a
copy of the proposed subtenant's or assignee's most recent annual financial
statement, (iii) all of the terms and provisions upon which the proposed
subletting or assignment is to be made and such other information concerning the
proposed subtenant or assignee as the Tenant has obtained in connection with the
proposed subletting or assignment. The Tenant shall reimburse the Landlord
promptly for reasonable legal and other expense incurred by the Landlord in
connection with any request by the Tenant for consent to any assignment or
subletting. If this Lease is assigned, or if the Premises or any part thereof is
sublet or occupied by anyone other than the Tenant, the Landlord may, at any
time and from time to time, collect rent and other charg-

                                       31
<PAGE>

es from the assignee, sublessee or occupant and apply the net amount collected
to the rent and other charges herein reserved, but no such assignment,
subletting, occupancy or collection shall be deemed a waiver of the prohibitions
contained in this Section 6.8 or the acceptance of the assignee, sublessee or
occupant as a tenant, or a release of the Tenant from the further performance by
the Tenant of covenants on the part of the Tenant herein contained. The Tenant
shall pay to the Landlord any amounts the Tenant receives from any subtenant or
assignee as rent, additional rent or other forms of compensation or
reimbursement other than those which are less than or equal to the then due and
payable proportionate monthly share of Annual Fixed Rent, Additional Rent and
all other monies due to Landlord pursuant to this Lease (allocable in the case
of a sublease to that portion of the Premises being subleased). The consent by
the Landlord to an assignment or subletting shall not be construed to relieve
the Tenant from obtaining the express consent in writing of the Landlord to any
further assignment or subletting.

      Without affecting any of its other obligations under this Lease, Tenant
will pay Landlord, as Additional Rent, all sums or other economic consideration
(deducting therefrom all brokerage commissions and legal fees, and deducting on
a monthly basis therefrom the Tenant's Initial Improvements Monthly Amortization
Amount) that (i) in the case of an assignment, are received by Tenant for such
assignment, and (ii) in the case of a subletting, are received by Tenant for
such subletting, whether or not denominated rentals under the sublease, to the
extent the same exceeds the sums which Tenant is obligated to pay Landlord under
this Lease (prorated, if a sublease of less than the entire Rentable Floor Area
of the Premises, on the basis of the portion of the Premises subject to such
sublease). The provisions of this paragraph shall not apply to a transfer to a
Permitted Transferee (as hereinafter defined).

      Landlord may elect, within thirty (30) days of receipt of written notice
from Tenant of any proposed assignment or sublease, prior to approving or
disapproving any proposed assignment or sublease, to repossess the space
proposed to be assigned or sublet. Landlord may thereafter lease the repossessed
space in such a manner as the landlord may in its sole discretion determine. In

                                       32
<PAGE>

the event Landlord elects to repossess the space as provided above, then all of
the Tenant's rights and obligations hereunder with respect to the repossessed
space shall cease and shall be of no further force and effect. The provisions of
this paragraph shall not apply to a transfer to a Permitted Transferee.

      The foregoing to the contrary notwithstanding, Tenant shall have the right
to assign this Lease or sublet the entire Premises (but not a portion thereof),
and Landlord shall give its consent to such an assignment or sublease, if the
proposed assignee or subtenant is (each of the following, a "Permitted
Transferee") (i) an entity owning one hundred percent (100%) of Tenant; (ii) an
entity into (or with which) Tenant is merged or consolidated; (iii) an entity
into which substantially all of Tenant's assets are transferred; (iv) an entity
under common control with Tenant; or (v) an entity all of whose ownership
interests shall, at the time, be owned directly by Pharmaceutical Peptides,
Inc., provided that:

            (a) such merger, consolidation or transfer of assets is for a good
business purpose and not a device for the transfer of Tenant's interest in this
Lease; and

            (b) the affiliate, subsidiary, parent, assignee or successor entity
has a net worth at least equal to the net worth of Tenant immediately prior to
such merger, consolidation or transfer, as evidenced by financial statements
prepared and certified by independent reputable certified public accountants.

      In any case where Landlord is required not to unreasonably withhold its
consent, provided Landlord has withheld its consent in good faith, Tenant's sole
remedy shall be injunctive relief.

7. Indemnity and Insurance

      7.1 Indemnity. To the maximum extent this agreement may be made effective
according to law, the Tenant agrees to indemnify, defend and save harmless the
Landlord from and against all claims, loss, or damage of whatever nature arising
from any breach by Tenant of any obligation of Tenant under this Lease or from
any act, omission or negligence of the Tenant, or the Tenant's contractors,
licensees, invitees, agents, servants or

                                       33
<PAGE>

employees, or arising from any accident, injury or damage whatsoever caused to
any person or property, occurring after the date that possession of the Premises
is first delivered to the Tenant and until the end of the Term and thereafter,
so long as the Tenant is in occupancy of any part of the Premises, in or about
the Premises or arising from any accident, injury or damage occurring outside
the Premises but within the Building, on the Land, within any adjacent area
maintained by Landlord or any individual or entity affiliated with Landlord,
where such accident, injury or damage results from an act or omission on the
part of the Tenant or the Tenant's agents or employees, licensees, invitees,
servants or contractors, provided that the foregoing indemnity shall not include
any cost or damage arising from any act, omission or negligence of the Landlord,
or the Landlord's contractors, licensees, invitees, agents, servants or
employees. This indemnity and hold harmless agreement shall include indemnity
against attorneys' fees and all other costs, expenses and liabilities incurred
or in connection with any such claim or proceeding brought thereon, and the
defense thereof.

      Throughout the Term, Landlord shall defend and save Tenant harmless and
indemnify Tenant from and against all bodily or personal injury, loss, claims or
damage to any personal property which results from the negligence or wilful
misconduct of Landlord, its employees, agents, or contractors.

      7.2 Liability Insurance. The Tenant agrees to maintain in full force from
the date upon which the Tenant first enters the Premises for any reason,
throughout the Term, and thereafter, so long as the Tenant is in occupancy of
any part of the Premises, a policy of comprehensive general liability insurance
under which the Landlord (and any individuals or entities affiliated with the
Landlord, and any holder of a mortgage on the Property of whom the Tenant is
notified by the Landlord) and the Tenant are named as insureds, and under which
the insurer provides a contractual liability endorsement insuring against all
cost, expense and liability arising out of or based upon any and all claims,
accidents, injuries and damages described in Section 7.1, in the broadest form
of such coverage from time to time available. Each such policy shall be
noncancellable and nonamendable (to the extent that any proposed amendment
reduces the limits or the scope of the insurance required

                                       34
<PAGE>

in this Lease) with respect to the Landlord and such ground lessors and
mortgagees without thirty (30) days' prior notice to the Landlord and such
mortgagees and, at the election of Landlord, either a certificate of insurance
or a duplicate original policy, together with evidence of payment of premiums
therefor reasonably satisfactory to Landlord, shall be delivered to the Landlord
on or before the Commencement Date (and at least thirty (30) days prior to the
expiration of any such policy of required insurance). The minimum limits of
liability of such insurance as of the Commencement Date shall be Three Million
Dollars ($3,000,000.00) for combined bodily injury (or death) and damage to
property (per occurrence), and from time to time during the Term such limits of
liability shall be increased to reflect such higher limits as are customarily
required pursuant to new leases of space in the Boston-Cambridge area with
respect to similar properties.

      7.3 Personal Property at Risk. The Tenant agrees that all of the
furnishings, fixtures, equipment, effects and property of every kind, nature and
description of the Tenant and of all persons claiming by, through or under the
Tenant which, during the continuance of this Lease or any occupancy of the
Premises by the Tenant or anyone claiming under the Tenant, may be on the
Premises or elsewhere in the Building or on the Lot shall be at the sole risk
and hazard of the Tenant, and if the whole or any part thereof shall be
destroyed or damaged by fire, water or otherwise, or by the leakage or bursting
of water pipes, steam pipes, or other pipes, by theft or from any other cause,
no part of said loss or damage is to be charged to or be borne by the Landlord,
except that the Landlord shall in no event be exonerated from any liability to
the Tenant or to any person, for any injury, loss, damage or liability caused by
any negligence or willful misconduct of Landlord or Landlord's agents,
employees, or contractors.

      7.4 Waiver of Subrogation. Any insurance carried by either party with
respect to the Building, Land, Premises, parking facilities or any property
therein or occurrences thereon shall, without further request by either party,
if it can be so written without additional premium, or with an additional
premium which the other party elects to pay, include a clause or endorsement
denying to the insurer rights of subrogation against the

                                       35
<PAGE>

other party to the extent rights have been waived by the insured prior to
occurrence of injury or loss. Each party, notwithstanding any provisions of this
Lease to the contrary, hereby waives any rights of recovery against the other
for injury or loss, including, without limitation, injury or loss caused by
negligence of such other party, due to hazards covered by insurance containing
such clause or endorsement to the extent of the indemnification received
thereunder.

      7.5 Landlord's Insurance. During the Term, Landlord shall carry and
maintain the following coverages of insurance (collectively, "Landlord's
Insurance"): (i) Fire and extended coverage insurance covering the Building and
Tenant's Leasehold Improvements to the extent of the full replacement value
thereof; and (ii) commercial general liability insurance in amounts Landlord
reasonably deems prudent. Notwithstanding anything to the contrary contained
herein, Tenant shall pay to Landlord the amount of Landlord's property and
casualty insurance premiums which are allocable to Tenant's leasehold
improvements, which amount shall not be included in Operating Expenses.

8. Casualty and Eminent Domain

      8.1 Restoration Following Casualties. If, during the Term, the Building or
Premises shall be damaged by fire or casualty, subject to the exceptions and
limitations provided below, the Landlord shall proceed promptly to exercise
reasonable efforts to restore the Building and Premises (including Tenant's
Leasehold Improvements, but excluding all moveable equipment and furnishings not
attached to the Premises and Tenant's other personal property) to substantially
the condition thereof at the time of such damage, but the Landlord shall not be
responsible for delay in such restoration which may result from any cause beyond
the reasonable control of the Landlord. The Landlord shall have no obligation to
expend in the reconstruction of the Building and Premises more than the actual
amount of insurance proceeds made available by its insurer. Any restoration of
the Building or the Premises shall be altered to the extent necessary to comply
with then current laws and applicable codes.

                                       36
<PAGE>

      8.2 Landlord's Termination Election. If in the opinion of the Landlord the
Building has been so damaged that it is appropriate for the Landlord to raze or
substantially alter the Building, then the Landlord may terminate this Lease by
giving notice to the Tenant within sixty (60) days after the date of the
casualty or such later date as is required to allow the Landlord a reasonable
time to make either such determination; provided, however, that Landlord may not
terminate this Lease pursuant to this paragraph unless Landlord similarly
terminates the leases of other tenants covering at least fifty percent (50%) of
the Building (excluding from such calculation space in the Building occupied by
Landlord). Any such termination shall be effective on the date designated in
such notice from the Landlord, but in any event, not later than sixty (60) days
after such notice, and if no date is specified, effective upon the delivery of
such notice.

      8.3 Tenant's Termination Election. Unless Landlord has earlier advised
Tenant of Landlord's election to terminate this Lease pursuant to Section 8.2,
or has earlier commenced to restore the Premises and maintain this Lease in
effect pursuant to Section 8.1, the Tenant shall have the right after the
expiration of sixty (60) days after any casualty which materially impairs a
material portion of the Premises to give a written notice to the Landlord
requiring the Landlord within ten (10) days thereafter to either (a) exercise or
waive any right of the Landlord to terminate this Lease pursuant to Section 8.2
as a result of such casualty, or (b) give written notice that Landlord intends
to restore the Premises pursuant to Section 8.1 and if the Landlord fails to
give timely response to the Tenant's notice, the Tenant shall be entitled to
give notice to the Landlord terminating this Lease. Where the Landlord is
obligated to exercise reasonable efforts to restore the Premises, unless such
restoration is completed within two hundred seventy (270) days from the date of
the casualty or taking, such period to be subject, however, to extension where
the delay in completion of such work is due to External Causes, the Tenant shall
have the right to terminate this Lease at any time after the expiration of such
two hundred seventy (270) days (as extended) period until the restoration is
substantially completed, such termination to take effect as of the date of the
Tenant's notice.

                                       37
<PAGE>

      8.4 Casualty at Expiration of Lease. If the Premises shall be damaged by
fire or casualty in such a manner that the Premises cannot, in the ordinary
course, reasonably be expected to be repaired within one hundred and twenty
(120) days from the commencement of repair work and such damage occurs within
the last eighteen (18) months of the Term (as the same may have been extended
prior to such fire or casualty), either party shall have the right, by giving
notice to the other not later than sixty (60) days after such damage, to
terminate this Lease, whereupon this Lease shall terminate as of the date of
such notice.

      8.5 Eminent Domain. Except as hereinafter provided, if the Premises, or
such portion thereof as to render the balance (if reconstructed to the maximum
extent practicable in the circumstances) unsuitable for the Tenant's purposes,
shall be taken by condemnation or right of eminent domain, the Landlord or the
Tenant shall have the right to terminate this Lease by notice to the other of
its desire to do so, provided that such notice is given not later than thirty
(30) days after the effective date of such taking. If so much of the Building
shall be so taken that the Landlord determines that it would be appropriate to
raze or substantially alter the Building, the Landlord shall have the right to
terminate this Lease by giving notice to the Tenant of the Landlord's desire to
do so not later than thirty (30) days after the effective date of such taking;
provided, however, that Landlord may not terminate this Lease pursuant to this
paragraph unless Landlord similarly terminates the leases of other tenants
covering at least fifty percent (50%) of the Building (excluding from such
calculation space in the Building occupied by Landlord).

      Should any part of the Premises be so taken or condemned during the Term,
and should this Lease be not terminated in accordance with the foregoing
provisions, the Landlord agrees to use reasonable efforts to put what may remain
of the Premises into proper condition for use and occupation as nearly like the
condition of the Premises prior to such taking as shall be practicable, subject,
however, to applicable laws and codes then in existence and to the availability
of sufficient proceeds from the eminent domain taking.

                                       38
<PAGE>

      8.6 Rent After Casualty or Taking. If the Premises shall be damaged by
fire or other casualty, except as provided below, the Annual Fixed Rent and
Additional Rent shall be justly and equitably abated and reduced according to
the nature and extent of the loss of use thereof suffered by the Tenant. If the
fire or other casualty was caused by Tenant, such abatement shall be made only
to the extent that Landlord is fully compensated therefore by any lost rent
insurance. In the event of a taking which permanently reduces the area of the
Premises, a just proportion of the Annual Fixed Rent shall be abated for the
remainder of the Term.

      8.7 Temporary Taking. In the event of any taking of the Premises or any
part thereof for a temporary use not in excess of six (6) months, (i) this Lease
shall be and remain unaffected thereby and Annual Fixed Rent and Additional Rent
shall not abate, and (ii) the Tenant shall be entitled to receive for itself
such portion or portions of any award made for such use with respect to the
period of the taking which is within the Term.

      8.8 Taking Award. Except as otherwise provided in Section 8.7, the
Landlord shall have and hereby reserves and excepts, and the Tenant hereby
grants and assigns to the Landlord, all rights to recover for damages to the
Building and the Land, and the leasehold interest hereby created, and to
compensation accrued or hereafter to accrue by reason of such taking, damage or
destruction, as aforesaid, and by way of confirming the foregoing, the Tenant
hereby grants and assigns to the Landlord, all rights to such damages or
compensation. Nothing contained herein shall be construed to prevent the Tenant
from prosecuting in any condemnation proceedings a claim for relocation
expenses, provided that such action shall not affect the amount of compensation
otherwise recoverable by the Landlord from the taking authority pursuant to the
preceding sentence.

9. Default

      9.1 Tenant's Default. Each of the following shall constitute an Event of
Default:

            (a) Failure onto the part of Tenant to pay the Annual Fixed Rent on
or before the date on which the same shall become due and payable, if such
condition

                                       39
<PAGE>

continues for five (5) days after notice from Landlord that the same is due
(except that the giving of such written notice of default, and the cure period
which follows, shall no longer be required as a condition to the occurrence of
an Event of Default on the third or any further occasion of monetary default
occurring within a twelve (12) consecutive month period).

            (b) Failure on the part of the Tenant to pay the Additional Rent or
other charges for which provision is made herein on or before the date on which
the same become due and payable, if such condition continues for ten (10) days
after notice from the Landlord that the same are delinquent (except that the
giving of such written notice of default, and the cure period which follows,
shall no longer be required as a condition to the occurrence of an Event of
Default on the third or any further occasion of monetary default occurring
within a twelve (12) consecutive month period).

            (c) Failure on the part of the Tenant to perform or observe any
other term or condition contained in this Lease if the Tenant shall not cure
such failure within thirty (30) days after notice from the Landlord to the
Tenant thereof, provided that in the case of breaches of obligations under this
Lease which are susceptible to cure but cannot be cured within thirty (30) days
through the exercise of due diligence, so long as the Tenant commences such cure
within thirty (30) days, such breach remains susceptible to cure, and the Tenant
diligently pursues such cure, such breach shall not be deemed to create an Event
of Default.

            (d) The taking of the estate hereby created on execution or by other
process of law; or a judicial declaration that the Tenant is bankrupt or
insolvent according to law; or any assignment of the property of the Tenant for
the benefit of creditors; or the appointment of a receiver, guardian,
conservator, trustee in bankruptcy or other similar officer to take charge of
all or any substantial part of the Tenant's property by a court of competent
jurisdiction; or the filing of an involuntary petition against the Tenant under
any provisions of the bankruptcy act now or hereafter enacted if the same is not
dismissed within one hundred twenty (120) days; the filing by the Tenant of any
voluntary petition

                                       40
<PAGE>

for relief under provisions of any bankruptcy law now or hereafter enacted.

      If an Event of Default shall occur, then, in any such case, whether or not
the Term shall have begun, the Landlord lawfully may, immediately or at any time
thereafter, give notice to the Tenant specifying the Event of Default and this
Lease shall come to an end on the date specified therein as fully and completely
as if such date were the date herein originally fixed for the expiration of the
Lease Term, and the Tenant will then quit and surrender the Premises to the
Landlord, but the Tenant shall remain liable as hereinafter provided.

      9.2 Damages. In the event that this Lease is terminated, the Tenant
covenants to pay to the Landlord all the sums ("Periodic Payments") and perform
all the obligations which the Tenant covenants in this Lease to pay and to
perform in the same manner and to the same extent and at the same time as if
this Lease had not been terminated (in calculating the amounts to be paid by the
Tenant under the foregoing covenant, the Tenant shall be credited with the net
proceeds of any rent obtained by reletting the Premises, after deducting all the
Landlord's expenses in connection with such reletting, including, without
limitation, all repossession costs, brokerage commissions, fees for legal
services and expenses of preparing the Premises for such reletting). Suit or
suits for the recovery of such damages, or any installments thereof, may be
brought by Landlord from time to time at its election, and nothing contained
herein shall be deemed to require Landlord to postpone suit until the date when
the Term would have expired if the Lease had not been so terminated or had
Landlord not re-entered the Premises.

      Landlord may, at its election made at any time after this Lease is
terminated, require Tenant to pay an amount (the "Lump Sum Payment") equal to
the excess, if any, of the discounted present value of the total rent reserved
for the remainder of the Term over the then discounted present fair rental value
of the Premises for the remainder of the Term (in calculating the rent reserved,
there shall be included, in addition to the Annual Fixed Rent and all Additional
Rent, the value of all other considerations agreed to be paid or performed by
the Tenant over the remainder of the Term). Upon payment of the Lump Sum

                                       41
<PAGE>

Payment, Tenant shall not thereafter be responsible for Periodic Payments.

      Landlord may (i) relet the Premises, or any part or parts thereof, for a
term or terms which may, at the Landlord's option, exceed or be equal to or less
than the period which would otherwise have constituted the balance of the Term,
and may grant such concessions and free rent as the Landlord in its reasonable
commercial judgment considers advisable or necessary to relet the same and (ii)
make such alterations, repairs and improvements in the Premises as the Landlord
in its reasonable commercial judgment considers advisable or necessary to relet
the same. No action of the Landlord in accordance with the foregoing or failure
to relet or to collect rent under reletting shall operate to release or reduce
Tenant's liability. The Landlord shall be entitled to seek to rent other
properties of the Landlord prior to reletting the Premises.

      9.3 Cumulative Rights. The specific remedies to which the Landlord may
resort under the terms of this Lease are cumulative and are not intended to be
exclusive of any other remedies or means of redress to which it may be lawfully
entitled in case of any breach or threatened breach by the Tenant of any
provisions of this Lease. In addition to the other remedies provided in this
Lease, the Landlord shall be entitled to the restraint by injunction of the
violation or attempted or threatened violation of any of the covenants,
conditions or provisions of this Lease or to a decree compelling specific
performance of any such covenants, conditions or provisions. Nothing contained
in this Lease shall limit or prejudice the right of the Landlord to prove for
and obtain in proceedings for bankruptcy, insolvency or like proceedings by
reason of the termination of this Lease, an amount equal to the maximum allowed
by any statute or rule of law in effect at the time when, and governing the
proceedings in which, the damages are to be proved, whether or not the amount be
greater, equal to, or less than the amount of the loss or damages referred to
above.

      9.4 Landlord's Self-help. After an Event of Default, the Landlord shall
have the right, but not the obligation, upon reasonable, but in no event less
than thirty (30) days' notice to the Tenant (except in case of emergency in
which case no notice need be given), to

                                       42
<PAGE>

perform such obligation. The Landlord may exercise its rights under this Section
without waiving any other of its rights or releasing the Tenant from any of its
obligations under this Lease.

      9.5 Enforcement Expenses. The Tenant shall promptly reimburse the Landlord
for all costs and expenses, including without limitation legal fees, incurred by
the Landlord in exercising and enforcing its rights under this Lease following
an Event of Default on the part of the Tenant, together with interest at the
Default Interest Rate (as hereinafter defined) from the date paid by the
Landlord.

      9.6 Late Charges and Interest on Overdue Payments. In the event that any
payment of Annual Fixed Rent or Additional Rent shall remain unpaid for a period
of two (2) business days following notice by the Landlord to the Tenant that
such payment is overdue, there shall become due to the Landlord from the Tenant,
as Additional Rent and as compensation for the Landlord's extra administrative
costs in investigating the circumstances of late rent, a late charge of two
percent (2%) of the amount overdue. In addition, any Annual Fixed Rent and
Additional Rent not paid when due shall bear interest from the date due to the
Landlord until paid at the variable rate (the "Default Interest Rate") equal to
the higher of (i) the rate at which interest accrues on amounts not paid when
due under the terms of the Landlord's financing for the Building, as from time
to time in effect, and (ii) two percent (2%) per annum in excess of the rate
from time to time announced by The First National Bank of Boston as its base
rate, or if such rate can no longer be determined, two percent (2%) per annum in
excess of the rate from time to time announced by a major commercial bank
selected by the Landlord as its base or prime rate; provided, however that if
the payment of any interest due hereunder would subject Landlord to any penalty
under applicable law, then the payments due hereunder shall be automatically
reduced to what they would be at the highest rate authorized under applicable
law.

      9.7 Landlord's Right to Notice and Cure. The Landlord shall in no event be
in default in the performance of any of the Landlord's obligations hereunder
unless and until the Landlord shall have failed to per-

                                       43
<PAGE>

form such obligations within thirty (30) days, or such additional time as is
reasonably required to correct any such default not susceptible to being cured
within such thirty (30) day period (provided that Landlord diligently pursues
such cure), after notice by the Tenant to the Landlord expressly specifying
wherein the Landlord has failed to perform any such obligation.

10. Mortgagees' Rights

      10.1 Subordination. This Lease shall, at the election of the holder of any
mortgage on the Property, be subject and subordinate to any and all mortgages on
the Property, so that the lien of any such mortgage shall be superior to all
rights hereby or hereafter vested in the Tenant. Tenant's agreement to
subordinate this Lease to any and all mortgages on the Property is conditioned
upon the execution and delivery of a non-disturbance agreement by such mortgagee
in such mortgagee's then-customary form. Landlord represents and warrants that,
on the date hereof, the Property is not encumbered by a mortgage.

      10.2 Prepayment of Rent not to Bind Mortgagee. No Annual Fixed Rent,
Additional Rent, or any other charge payable to the Landlord shall be paid more
than thirty (30) days prior to the due date thereof under the terms of this
Lease and payments made in violation of this provision shall (except to the
extent that such payments are actually received by a mortgagee or ground lessor)
be a nullity as against such mortgagee or ground lessor and the Tenant shall be
liable for the amount of such payments to such mortgagee or ground lessor.

      10.3 Tenant's Duty to Notify Mortgagee: Mortgagee's Ability to Cure. No
act or failure to act on the part of the Landlord which would entitle the Tenant
under the terms of this Lease, or by law, to be relieved of the Tenant's
obligations to pay Annual Fixed Rent or Additional Rent hereunder or to
terminate this Lease, shall result in a release or termination of such
obligations of the Tenant or a termination of this Lease unless (i) the Tenant
shall have first given written notice of the Landlord's act or failure to act to
the Landlord's mortgagees or ground lessors of record, if any, of whose identity
and address the Tenant shall have been given notice, specifying the act or
failure to act on the part

                                       44
<PAGE>

of the Landlord which would give basis to the Tenant's rights; and (ii) such
mortgagees or ground lessors, after receipt of such notice, have failed or
refused to correct or cure the condition complained of within the grace period
provided to Landlord hereunder.

      10.4 Estoppel Certificates. The Tenant shall from time to time, upon not
less than fifteen (15) days' prior written request by the Landlord, execute,
acknowledge and deliver to the Landlord a statement in writing certifying to the
Landlord or an independent third party, with a true and correct copy of this
Lease attached thereto, (i) that this Lease is unmodified and in full force and
effect (or, if there have been any modifications, that the same is in full force
and effect as modified and stating the modifications); (ii) that the Tenant has
no knowledge of any defenses, offsets or counterclaims against its obligations
to pay the Annual Fixed Rent and Additional Rent and to perform its other
covenants under this Lease (or if there are any defenses, offsets, or
counterclaims, setting them forth in reasonable detail); (iii) that there are no
known uncured defaults of the Landlord or the Tenant under this Lease (or if
there are known defaults, setting them forth in reasonable detail); (iv) the
dates to which the Annual Fixed Rent, Additional Rent and other charges have
been paid; (v) that the Tenant has accepted, is satisfied with, and is in full
possession of the Premises, including all improvements, additions, and
alterations thereto required to be made by Landlord under the Lease; (vi) that
the Landlord has satisfactorily complied with all of the requirements and
conditions precedent to the commencement of the Term of the Lease as specified
in the Lease; (vii) the Term, the Commencement Date, and any other relevant
dates, and that the Tenant has been in occupancy since the Commencement Date and
paying rent since the specified dates; (viii) that no monetary or other
considerations, including, but not limited to, rental concessions for Landlord,
special tenant improvements or Landlord's assumption of prior lease obligations
of Tenant have been granted to Tenant by Landlord for entering into the Lease,
except as specified; (ix) that Tenant has no notice of a prior assignment,
hypothecation, or pledge of rents or of the Lease; (x) that the Lease represents
the entire agreement between Landlord and Tenant (unless there are amendments,
in which case all amendments shall be specified); and (xi) such other matters
with respect to the Tenant and

                                       45
<PAGE>

this Lease as the Landlord may reasonably request. On the Commencement Date,
Tenant shall, at the request of Landlord, promptly execute, acknowledge and
deliver to Landlord a statement in writing that the Commencement Date has
occurred, that the Annual Fixed Rent has begun to accrue (if true) and that
Tenant has taken occupancy of the Premises. Any statement delivered pursuant to
this Section may be relied upon by any prospective purchaser or mortgagee of the
Property and shall be binding on the Tenant.

      Landlord shall from time to time, upon not less than fifteen (15) days'
prior request by Tenant, execute, acknowledge and deliver to Tenant a statement
in writing certifying to Tenant or an independent third party, that (i) this
Lease has not been modified and is in full force and effect or, if there has
been a modification of this Lease, that this Lease is in full force and effect
as modified, stating such modifications, (b) the dates to which the Annual Fixed
Rent and Additional Rent have been paid, (c) whether or not, to the knowledge of
the Landlord, Tenant is in default, and, if Tenant is in default, stating the
nature of such default, (d) whether or not there are then existing any set-offs
or defenses against the enforcement of any of the obligations hereunder upon the
part of Landlord or Tenant, as the case may be, to be performed or complied with
(and, if so, specifying the same).

11. Miscellaneous

      11.1 Recording of Lease. The Tenant agrees not to record this Lease, and
any attempted or actual recording thereof by Tenant shall be an Event of Default
hereunder. At Tenant's request, the parties shall execute and deliver a notice
of lease in form and substance reasonably satisfactory to both parties for the
purpose of recording, but said notice of lease shall not in any circumstance be
deemed to modify or to change any of the provisions of this Lease.

      11.2 Notices. Whenever any notice, approval, consent, request, election,
offer or acceptance is given or made pursuant to this Lease, it shall be in
writing. Communications and payments shall be addressed, if to the Landlord, at
the Landlord's Original Address as set forth in Exhibit A or at such other
address as may have been

                                       46
<PAGE>

specified by prior notice to the Tenant, with a copy sent to Joseph W. Haley,
P.C., Goodwin, Procter & Hoar, One Exchange Place, Boston, MA 02108, and if to
the Tenant prior to the Commencement Date, at the Tenant's Original Address, and
after the Commencement Date, at the Premises, or at such other place as may have
been specified by prior notice to the Landlord, with a copy of default notices
sent to Kent A. Coit, Esq., Skadden, Arps, Slate, Meagher & Flom, One Beacon
Street, Boston, MA 02108, and a copy of all notices to Ethan Signer, Ph.D at the
Premises. Any communication so addressed shall be deemed duly given on the
earlier of (i) the date received or (ii) on the third business day following the
day of mailing if mailed by registered or certified mail, return receipt
requested. If the Landlord by notice to the Tenant at any time designates some
other person to receive payments or notices, all payments or notices thereafter
by the Tenant shall be paid or given to the agent designated until notice to the
contrary is received by the Tenant from the Landlord.

      11.3 Successors and Limitation on Liability of the Landlord. The
obligations of this Lease shall run with the land, and this Lease shall be
binding upon and inure to the benefit of the parties hereto and their respective
successors and assigns, except that the original landlord named herein and each
successor landlord shall be liable only for obligations accruing during the
period of its ownership. The obligations of the Landlord shall be binding only
upon the assets of the Landlord consisting of the ownership of the Property but
not upon other assets of the Landlord and neither the Tenant, nor anyone
claiming by, under or through the Tenant, shall be entitled to obtain any
judgment creating personal liability on the part of the Landlord or enforcing
any obligations of the Landlord against any assets of the Landlord other than
the ownership of the Property. In no event shall any partner, officer, director,
trustee, stockholder, employee or beneficiary of Landlord be held to have any
personal liability for satisfaction of any claims or judgments that Tenant may
have against Landlord.

      11.4 Waivers by the Landlord. The failure of the Landlord or the Tenant to
seek redress for violation of, or to insist upon strict performance of, any
covenant or condition of this Lease, shall not be deemed a waiver of such
violation nor prevent a subsequent act, which would

                                       47
<PAGE>

have originally constituted a violation, from having all the force and effect of
an original violation. Neither the receipt by the Landlord, nor the payment by
Tenant, of Annual Fixed Rent or Additional Rent with knowledge of the breach of
any covenant of this Lease shall be deemed a waiver of such breach. No provision
of this Lease shall be deemed to have been waived by the Landlord, unless such
waiver be in writing signed by the Landlord. No consent or waiver, express or
implied, by Landlord or Tenant to or of any breach of any agreement or duty
shall be construed as a waiver or consent to or of any other breach of the same
or any other agreement or duty.

      11.5 Acceptance of Partial Payments of Rent. No acceptance by the Landlord
of a lesser sum than the Annual Fixed Rent and Additional Rent then due shall be
deemed to be other than a partial installment of such rent due, nor shall any
endorsement or statement on any check or any letter accompanying any check or
payment as rent be deemed an accord and satisfaction, and the Landlord may
accept such check or payment as without prejudice to the Landlord's right to
recover the balance of such installment or pursue any other remedy in this Lease
provided. The delivery of keys to any employee of the Landlord or to the
Landlord's agent or any employee thereof shall not operate as a termination of
this Lease or a surrender of the Premises.

      11.6 Interpretation and Partial Invalidity. If any term of this Lease, or
the application thereof to any person or circumstances, shall to any extent be
invalid or unenforceable, the remainder of this Lease, or the application of
such term to persons or circumstances other than those as to which it is invalid
or unenforceable, shall not be affected thereby, and each term of this Lease
shall be valid and enforceable to the fullest extent permitted by law. The
titles of the Articles are for convenience only and not to be considered in
construing this Lease. This Lease contains all of the agreements of the parties
with respect to the subject matter thereof and supersedes all prior dealings
between them with respect to such subject matter.

      11.7 Quiet Enjoyment. So long as the Tenant pays Annual Fixed Rent and
Additional Rent, performs all other Tenant covenants of this Lease and observes
all conditions hereof, the Tenant shall peaceably and quietly

                                       48
<PAGE>

have, hold and enjoy the Premises free of any claims by, through or under the
Landlord.

      11.8 Brokerage. Landlord and Tenant each represent and warrant to the
other that it has had no dealings with any broker or agent other than Lynch
Murphy Walsh & Partners ("Broker") in connection with this Lease and shall
indemnify and hold harmless the other from claims for any brokerage commission
other than that due Broker arising out of such party's action.

      11.9 Surrender of Premises and Holding Over. The Tenant shall surrender
possession of the Premises on the last day of the Term and the Tenant waives the
right to any notice of termination or notice to quit. The Tenant covenants that
upon the expiration or sooner termination of this Lease, it shall, without
notice, deliver up and surrender possession of the Premises in the same
condition in which the Tenant has agreed to keep the same during the continuance
of this Lease and in accordance with the terms hereof, normal wear and tear
excepted, first removing therefrom all goods and effect of the Tenant and any
leasehold improvements Landlord specified for removal pursuant to Section 4.2,
and repairing all damage caused by such removal. Upon the expiration of this
Lease or if the Premises should be abandoned by the Tenant, or this Lease should
terminate for any cause, and at the time of such expiration, vacation,
abandonment or termination, the Tenant or Tenant's agents, subtenants or any
other person should leave any property of any kind or character on or in the
Premises, the fact of such leaving of property on or in the Premises shall be
conclusive evidence of intent by the Tenant, and individuals and entities
deriving their rights through the Tenant, to abandon such property so left in or
upon the Premises, and such leaving shall constitute abandonment of the
property. Landlord shall have the right and authority without notice to the
Tenant or anyone else, to remove and destroy, or to sell or authorize dispose of
such property, or any part thereof, without being in any way liable to the
Tenant therefor and the proceeds thereof shall belong to the Landlord as
compensation for the removal and disposition of such property.

      If the Tenant fails to surrender possession of the Premises upon the
expiration or sooner termination of this Lease, the Tenant shall pay to
Landlord, as rent for

                                       49
<PAGE>

any period after the expiration or sooner termination of this Lease an amount
equal to one hundred fifty percent (150%) the Annual Fixed Rent and the
Additional Rent required to be paid under this Lease as applied to any period in
which the Tenant shall remain in possession. Acceptance by the Landlord of such
payments shall not constitute a consent to a holdover hereunder or result in a
renewal or extension of the Tenant's rights of occupancy. Such payments shall be
in addition to and shall not affect or limit the Landlord's right of re-entry,
Landlord's right to collect such damages as may be available at law, or any
other rights of the Landlord under this Lease or as provided by law.

      11.10 Landlord's Lien. To secure the payment of all Annual Fixed Rent and
Additional Rent, and the performance of all other obligations hereunder, Tenant
hereby grants to Landlord a first lien and security interest on the personal
property listed on Exhibit D-2 (the "Secured Property"), and also upon all
proceeds of any insurance that may accrue to Tenant by reason of the destruction
or damage of the Secured Property. Tenant will not remove the Secured Property
from the Premises without the prior written consent of Landlord, which consent
shall not be unreasonably withheld; provided, however, that Tenant replaces such
item(s) of Secured Property with replacement item(s) of equal or greater value
and that any such removal does not change the character of the Premises as
laboratory space nor have a detrimental effect on the value thereof. Tenant
waives the benefit of all exemption laws in favor of this lien and security
interest. Upon the occurrence of an Event of Default hereunder, this lien may be
foreclosed with or without court proceedings by private or public sale, so long
as Landlord gives Tenant at least ten (10) days notice of the time and place of
such sale. Landlord will have the right to become the purchaser if it is the
highest bidder at the sale. Contemporaneously with its execution of this Lease,
and if requested by Landlord after such extension, Tenant will execute and
deliver to Landlord Uniform Commercial Code financing statements in form and
substance sufficient (upon proper filing) to perfect the security interest
granted in this Section 11.10. If requested Landlord, Tenant will also execute
and deliver to Landlord, within five (5) days of Landlord request, any Uniform
Commercial Code continuation statements in form and substance sufficient to
reflect any

                                       50
<PAGE>

proper amendment of, modification in, or extension of the security interest
granted in this Section 11.10. The parties hereto agree that this Lease
constitutes a security agreement and that the recordation of a notice of this
Lease shall constitute a fixture filing pursuant to and under the Massachusetts
Uniform Commercial Code. The provisions of this Section 11.10 shall survive the
expiration or earlier termination of this Lease.

      11.11 Right of First Offer. Unless an Event of Default has occurred and is
continuing, before entering into a lease with a third party unaffiliated with
Landlord for any other space in the Building ("Additional Space"), Landlord will
notify Tenant of the availability of Additional Space and the principal terms
and conditions, including the rent and other economic terms (the "Rental Terms,"
and, together with such other principal terms and conditions, the "offered
Terms") on which Landlord would be willing to lease the Additional Space to
Tenant ("Landlord's Offer"). Tenant may, by notice to Landlord given without
thirty (30) days of being given Landlord's Offer, either:

            (i) give Landlord notice that Tenant has elected to lease the
      Additional Space on the Offered Terms ("Tenant's Acceptance"), or

            (ii) give Landlord notice rejecting Landlord's Offer, but containing
      a counteroffer ("Tenant's Counteroffer") which sets forth the Rental Terms
      on which Tenant would be willing to lease the Additional Space, but
      otherwise on the Offered Terms (the "Counteroffer Terms"), or

            (iii) give Landlord notice rejecting Landlord's Offer ("Tenant's
      Rejection"), but not containing a Tenant's Counteroffer which fulfills the
      conditions of clause (ii) above; Tenant's failure to timely give either
      Tenant's Acceptance or Tenant's Counteroffer shall constitute Tenant's
      Rejection.

      If Tenant timely gives Tenant's Acceptance with respect to Landlord's
Offer, then Tenant shall execute a lease for the Additional Space, on
substantially the same terms and conditions of this Lease, except as modified to
incorporate the Offered Terms and such other matters as

                                       51
<PAGE>

are reasonably required by Landlord, within five (5) days of being delivered an
execution counterpart thereof by Landlord. Tenant's failure to timely do so
shall constitute a revocation of Tenant's Acceptance and all of the terms
relating to Tenant's Rejection shall apply instead. If Tenant timely executes
such a lease, Landlord will execute the same.

      If Tenant timely makes a Tenant's Counteroffer to Landlord's Offer, then:

            (a) At any time during the period commencing on the date that
Landlord receives Tenant's Counteroffer and ending on the date that is one
hundred fifty (150) days thereafter, Landlord may, by notice to Tenant (the "Put
Notice") require Tenant to lease the Additional Space on the Counteroffer Terms.
If Landlord timely gives Tenant a Put Notice, then Tenant shall execute a lease
for the Additional Space, on substantially the same terms and conditions of this
Lease, except as modified to incorporate the Counteroffer Terms and such other
matters as are reasonably required by Landlord, within five (5) days of being
delivered an execution counterpart thereof by Landlord. Tenant's failure to
timely do so shall constitute a revocation of Tenant's Counteroffer and all of
the terms relating to Tenant's Rejection shall apply instead. If Tenant timely
executes such a lease, Landlord will execute the same.

            (b) In addition to Landlord's right to give Tenant a Put Notice,
Landlord shall have a period (the "Market Period") of one (1) year from the date
that is the earlier to occur of (x) the date that is thirty (30) days following
Landlord's delivery to Tenant of Landlord's Offer or (y) the date that Landlord
receives Tenant's Counteroffer, to lease the Additional Space on any terms and
conditions; provided, however, that before Landlord can lease the Additional
Space on Rental Terms more favorable than those contained in Tenant's
Counter-offer, Landlord shall offer to lease the Additional Space to Tenant at
such more favorable Rental Terms. Landlord's offer to Tenant as aforesaid shall
constitute a Landlord's Offer for all purposes of this Section 11.11, except
that Tenant must respond within ten (10) days, rather than within the thirty
(30) day period set forth in the first paragraph of this Section 11.11.

                                       52
<PAGE>

            (c) If Landlord has not leased the Additional Space on or prior to
the expiration of the Market Period, then in the event Landlord desires to lease
the Additional Space to a third party unaffiliated with Landlord, Landlord must
again comply with the conditions of this Section 11.11.

      If Tenant either gives notice of, or is deemed to have given, Tenant's
Rejection, Tenant shall have no further rights to lease the Additional Space in
question.

      This right of first offer to lease the Additional Space is personal to
Pharmaceutical Peptides, Inc. and is not transferable upon any assignment of
this Lease except to a Permitted Transferee.

                                       53
<PAGE>

            IN WITNESS WHEREOF, the parties hereto have entered into this Lease
on the date and year first above written.

                                        The Charles Stark Draper
                                        Laboratory, Inc.

                                        By: /s/ David C. Driscoll
                                            ---------------------------------
                                        Name:  David C. Driscoll
                                               ------------------------------
                                        Title: Treasurer
                                               ------------------------------

                                        Pharmaceutical Peptides, Inc.

                                        By: /s/ Ethan R. Signer
                                            ---------------------------------
                                        Name:  Ethan R. Signer
                                               ------------------------------
                                        Title: Chief Executive Officer
                                               ------------------------------

                                       54
<PAGE>

                                    EXHIBIT A

                                Basic Lease Terms

Annual Fixed           Lease Year 1:             $195,000.00 ($13.00 per square
Rent for the                                     foot of Rentable Floor Area
Initial Term:                                    with respect to 15,000 square
                                                 feet of Rentable Floor Area,
                                                 and $0.00 per square foot of
                                                 Rentable Floor Area with
                                                 respect to 9,797 square feet of
                                                 Rentable Floor Area), subject
                                                 to the rent abatement provided
                                                 pursuant to Section 3.1.

                       Lease Year 2:             $258,680.50 ($13.00 per square
                                                 foot of Rentable Floor Area
                                                 with respect to 15,000 rentable
                                                 square feet of Rentable Floor
                                                 Area, and $6.50 per square foot
                                                 of Rentable Floor Area with
                                                 respect to 9,797 square feet of
                                                 Rentable Floor Area).

                       Lease Years 3-5:          $322,361.00 ($13.00 per square
                                                 foot of Rentable Floor Area
                                                 with respect to 24,797 square
                                                 feet of Rentable Floor Area).

                       Lease Years 6-10:         $347,158.00 ($14.00 per square
                                                 foot of Rentable Floor Area
                                                 with respect to 24,797 square
                                                 feet of Rentable Floor Area).

Term:                  Beginning on the Commencement Date and ending on the date
                       this is ten (10) years following the Rent Commencement
                       Date.

                                       55
<PAGE>

Landlord's             The Charles Stark Draper Laboratory, Inc.
Original Address:      555 Technology Square
                       Cambridge, Massachusetts 02139
                       Attention:  David C. Driscoll, Treasurer

Premises:              The entire fifth (5th) floor of the Hill Building, One
                       Hampshire Street, Cambridge, MA containing 24,797 square
                       feet of Rentable Floor Area, a floor plan of which is
                       attached as Exhibit A-1.

Parking Privileges:    During the Term, Landlord shall provide up to a maximum
                       of twenty-five (25) parking permits, and Tenant shall
                       pay One Hundred Dollars ($100.00) per month per parking
                       permit. If Tenant initially desires fewer than twenty
                       five (25) parking spaces, Tenant may elect to take fewer
                       parking spaces. Tenant shall then be permitted to request
                       additional parking spaces, up to the maximum of
                       twenty-five (25) in the aggregate; provided, however,
                       that Tenant shall not be permitted to give up any parking
                       spaces previously requested.

Permitted Uses:        Laboratories and offices and accessory uses supporting
                       the foregoing.

Commencement           April ____, 1994
Date:

Rent Commencement      The date that is the earlier to occur of:
 Date:                 (i) the date when Tenant, any employee of Tenant, or any
                       person holding by, through or under Tenant first occupies
                       the Premises for the conduct of business; or (ii)
                       September 15, 1994.

Tenant's Original      Pharmaceutical Peptides, Inc.
Address:               c/o Lynch Murphy Walsh & Partners
                       One Financial Center, 13th Floor
                       Boston, Massachusetts 02111
                       Attention: Malcolm Gefter, Ph.D.

Total Rentable         171,599 square feet
Floor Area of
Building

                                       56
<PAGE>

                                   EXHIBIT A-1

                           FLOOR PLAN OF THE PREMISES
<PAGE>

                                    EXHIBIT B

                                STANDARD SERVICES

The following services are provided by the Landlord:

A.    Regular maintenance of interior, exterior and park ing lot landscaping.

B.    Regular maintenance, sweeping and snow removal of building exterior areas
      such as roadways, driveways, sidewalks, parking areas and courtyard
      paving.

C.    Exterior and interior cleaning of all exterior windows twice per year.

D.    Daily, weekday maintenance of hallways, passenger elevators, common area
      bathrooms and main lobby.

E.    Periodic cleaning of stairwells and freight elevators.

F.    Daily, weekday rubbish removal of all tenant trash from Premises.

G.    Maintenance and repair of base building surveillance and alarm equipment,
      mechanical, electrical, plumbing and life safety systems.

H.    Building surveillance and alarm system operation and live monitoring
      service to building standard specifications.

I.    Heating and air conditioning to maintain the Premises at comfortable
      temperatures shall be provided between the hours of 8:00 AM to 6:00 PM
      Monday through Friday. In other hours, air conditioning will be made
      available for $20 per hour. Heating will be provided at comfortable
      temperatures in other reasonable hours without additional charge.

J.    Normal elevator service from the freight and passenger elevators during
      the same hours and on a reduced basis as demand may require at other
      hours.
<PAGE>

K.    Utilities for all interior common areas and exterior building and parking
      lighting.

L.    Custodial Services pursuant to Exhibit E.

M.    Hot water for lavatory purposes and cold water for drinking, lavatory and
      toilet purposes.
<PAGE>

                                    EXHIBIT C

                              RULES AND REGULATIONS

DEFINITIONS

Wherever in these Rules and Regulations the word "Tenant" is used, it shall be
taken to apply to and include the Tenant and his agents, employees, invitees,
licensees, contractors, any subtenants and is to be deemed of such number and
gender as the circumstances require. The word "Premises" is to be taken to
include the space covered by the Lease. The word "Landlord" shall be taken to
include the employees and agents of Landlord. Other capitalized terms used but
not defined herein shall have the meanings set forth in the Lease.

GENERAL USE OF BUILDING

      A.    Space for admitting natural light into any public area or tenant
            space of the Building shall not be covered or obstructed by Tenant
            except in a manner approved by Landlord.

      B.    Toilets, showers and other like apparatus shall be used only for the
            purpose for which they were constructed. Any and all damage from
            misuse shall be borne by Tenant.

      C.    No sign, advertisement, notice or the like, shall be used in the
            Building by Tenant other than within the Premises and not visible
            from outside the Premises. If Tenant violates the foregoing,
            Landlord may remove the violation without liability and may charge
            all costs and expenses incurred in so doing to Tenant.

      D.    Tenant shall not throw or permit to be thrown anything out of
            windows. In addition, Tenant shall not do or permit anything which
            will obstruct, injure, annoy or interfere with other tenants or
            those having business with them, or affect any insurance rate on the
            Building or violate any provision of any insurance policy on the
            Building.
<PAGE>

      E.    No additional locks or similar devices shall be attached to any door
            or window and no keys other than those provided by the Landlord
            shall be made for any door unless permitted by Landlord. Upon
            termination of this lease or of the Tenant's possession, the Lessee
            shall surrender all keys to the Premises and shall explain to the
            Landlord all combination locks on safes, cabinets and vaults.

      F.    Tenant shall not install any shades, blinds, or awnings or any
            interior window treatment without consent of Landlord. All equipment
            of any electrical or mechanical nature shall be placed in settings
            which absorb and prevent any vibration or noise.

      G.    Landlord shall designate the time when and the method whereby
            freight, laboratory equipment, furniture, safes and other like
            articles may be brought into, moved or removed from the Building or
            Premises, and to designate the location for temporary disposition of
            such items.

      H.    Canvassing, soliciting and peddling in the Building is prohibited
            and Tenant shall cooperate to prevent the same from occurring.

      I.    Tenant shall not place a load on any floor of said Premises
            exceeding one hundred (100) pounds per square foot. Landlord
            reserves the right to prescribe the weight and position of all
            safes and heavy equipment.

      J.    Tenant shall not install or use any air conditioning or heating
            device or system other than those approved by Landlord.

      K.    Landlord shall have the right to make such other and further
            reasonable rules and regulations as in the judgment of Landlord,
            may from time to time be needful for the safety, appearance, care
            and cleanliness of the Building and for the preservation of good or-
            der therein. Landlord shall not be responsi-
<PAGE>

            ble to Tenant for any violation of rules and regulations by other
            tenants.

      L.    The loading areas, parking areas, sidewalks, entrances, lobbies,
            halls, walkways, elevators, stairways and other common areas
            provided by Landlord shall not be obstructed by Tenant, or used by
            Tenant for any other purpose than for ingress and egress.

      M.    In order to insure use and care of the Premises Tenant shall not
            enter any janitors' closets, mechanical or electrical areas,
            telephone closets, loading areas, roof or Building storage areas
            without the written consent of Landlord.
<PAGE>

                                    EXHIBIT D

                          TENANT'S INITIAL IMPROVEMENTS

      Approximately fifteen thousand (15,000) square feet of first-class
bio-technology laboratory space, consistent with similar facilities located in
the Metropolitan Boston area.
<PAGE>

                                   EXHIBIT D-1

                       LIST OF TENANT'S PERSONAL PROPERTY

            See three (3) sheets entitled "Pharmaceutical Peptides, Inc.
      Equipment Lease" attached hereto.
<PAGE>

                                   EXHIBIT D-2

                                SECURED PROPERTY

            All items incorporated within and made a part of Tenant's Initial
Improvements, excluding therefrom those items listed on Exhibit D-1.
<PAGE>

                                    EXHIBIT E

                               CUSTODIAL SERVICES

CUSTODIAL WORKERS:   WILL POSSESS A THOROUGH KNOWLEDGE OF THE OPERATION OF ALL
                     MECHANICAL CLEANING EQUIPMENT, ALL CLEANING METHODS, AND
                     ALL CLEANING MATERIALS. ALL CUSTODIAL WORKERS WILL BE
                     SUPERVISED ON A NIGHTLY BASIS.

                                    MATERIALS

      1.    ALL MECHANICAL CLEANING EQUIPMENT WILL BE FURNISHED BY DRAPER
            LABORATORY.

      2.    ALL CLEANING CHEMICALS, MATERIALS, AND CLEANING EQUIPMENT WILL BE
            FURNISHED BY DRAPER LABORATORY.

      3.    SANITARY NAPKIN VENDING MACHINES WILL BE RESTOCKED BY DRAPER
            LABORATORY. THE COST OF THESE SANITARY PRODUCTS WILL BE BORNE BY THE
            INDIVIDUAL USERS.

      4.    FLOOR FINISHES USED HAVE PASSED A SAFETY NON SLIP TEST.

      5.    ALL BATHROOM DESCALERS WILL BE LESS THAN 12 PERCENT HYDROCHLORIC
            ACID.

      6.    MATERIAL SAFETY DATA SHEETS WILL BE KEPT BY DRAPER LABORATORY ON ALL
            CLEANING CHEMICALS SUPPLIED.

                              CLEANING OF RESTROOMS

TASK                                 FREQUENCY
A.    REPLENISH SUPPLIES             DAILY
B.    CLEAN AND DISINFECT            DAILY
      ALL RESTROOM FIXTURES
C.    CLEAN MIRRORS                  DAILY
D.    CLEAN AND DISINFECT            DAILY
      PARTITIONS
E.    CLEAN AND DISINFECT            DAILY
      HARD SURFACE FLOORS
F.    EMPTY TRASH RECEPTACLES        DAILY
G.    REPLACE LINERS                 DAILY
      TRASH/SANITARY
H.    VACUUM LIGHT FIXTURES          AS NEEDED
      AND DIFFUSERS
I.    SPOT CLEAN WALLS               DAILY
J.    WASH WALLS                     AS NEEDED
K.    DESCALING OF FIXTURES          WEEKLY/OR AS NEEDEDExhibit 10.17

                                      LEASE

                                 By and Between

                      PRAECIS PHARMACEUTICALS INCORPORATED
                                   ("Lessee")

                                       and

                               BDG PISCATAWAY, LLC
                                   ("Lessor")

                             Dated: August 19, 1998
<PAGE>

                          TABLE OF CONTENTS

BASIC LEASE PROVISIONS AND DEFINITIONS..............................1

1.    DESCRIPTION...................................................3

2.    TERM. ........................................................4

3.    BASIC RENT....................................................4

4.    USE AND OCCUPANCY.............................................4

5.    CARE AND REPAIR OF PREMISES/ENVIRONMENTAL.....................4

6.    ALTERATIONS, ADDITIONS OR IMPROVEMENTS.......................13

7.    ASSIGNMENT AND SUBLEASE......................................15

8.    COMPLIANCE WITH RULES AND REGULATIONS........................20

9.    DAMAGES TO BUILDING/WAIVER OF SUBROGATION....................20

10.   EMINENT DOMAIN...............................................22

11.   INSOLVENCY OF LESSEE, OTHER DEFAULTS.........................25

12.   LESSOR'S REMEDIES ON DEFAULT.................................26

13.   DEFICIENCY...................................................26

14.   SUBORDINATION OF LEASE.......................................28

15.   SECURITY DEPOSIT/LETTER OF CREDIT............................28

16.   RIGHT TO CURE BREACH.........................................29

17.   LIENS........................................................29

                                        i
<PAGE>

18.   RIGHT TO INSPECT AND REPAIR..................................30

19.   SERVICES TO BE PROVIDED BY LESSOR............................31

20.   INTERRUPTION OF SERVICES OR USE..............................32

21.   ELECTRICAL AND OTHER UTILITY SERVICES........................32

22.   ADDITIONAL RENT..............................................34

23.   LESSEE'S ESTOPPEL............................................40

24.   HOLDOVER TENANCY.............................................41

25.   RIGHT TO SHOW PREMISES.......................................41

26.   LESSEE IMPROVEMENT WORK AND LESSEE ALLOWANCE.................41

27.   WAIVER OF JURY TRIAL/NON-MANDATORY COUNTERCLAIMS.............43

28.   LATE CHARGE..................................................43

29.   INSURANCE....................................................43

30.   NO OTHER REPRESENTATIONS.....................................48

31.   QUIET ENJOYMENT..............................................48

32.   INDEMNITY. ..................................................48

33.   APPLICABILITY TO HEIRS AND ASSIGNS...........................49

34.   PARKING SPACES...............................................50

35.   LESSOR'S EXCULPATION.........................................50

36.   RULES OF CONSTRUCTION/APPLICABLE LAW.........................50

37.   BROKER.......................................................51

                                       ii
<PAGE>

38.   PERSONAL LIABILITY...........................................51

39.   NO OPTION....................................................52

40.   DEFINITIONS. ................................................52

41.   LEASE COMMENCEMENT...........................................53

42.   NOTICES......................................................53

43.   ACCORD AND SATISFACTION......................................54

44.   EFFECT OF WAIVERS............................................54

45.   TIME OF ESSENCE..............................................54

46.   MORTGAGEE'S NOTICE AND OPPORTUNITY TO CURE...................54

47.   LESSOR'S RESERVED RIGHTS.....................................55

48.   CORPORATE AUTHORITY..........................................55

49.   GOVERNMENT REQUIREMENTS......................................55

50.   RENEWAL OPTION...............................................55

51.   SIGNS........................................................60

52.   LESSEE'S RIGHT TO TERMINATE LEASE............................61

53.   RIGHT OF FIRST OFFER.........................................61

54.   NON-COMPETE..................................................63

55.   USE OF ADDITIONAL FACILITIES.................................64

56.   REPRESENTATION OF CONDITIONS OF DEMISED PREMISES.............64

                                       iii
<PAGE>

57.   COUNTERPARTS.................................................64

                                     LEASE

            LEASE, made the 19th day of August, 1998 between BDG PISCATAWAY,
LLC, a New York limited liability company, whose address is c/o Blumenfeld
Development Group, Ltd., 6800 Jericho Turnpike, Syosset, New York 11791-4498
(hereinafter referred to as "Lessor"); and PRAECIS PHARMACEUTICALS INCORPORATED,
a Delaware corporation, whose address is 1 Hampshire Street, Cambridge,
Massachusetts 02139-1572 (hereinafter referred to as "Lessee").

                                   PREAMBLE

                    BASIC LEASE PROVISIONS AND DEFINITIONS

            In addition to other terms elsewhere defined in this Lease, the
following terms whenever used in this Lease should have only the meanings set
forth in this Section, unless such meanings are expressly modified, limited or
expanded elsewhere herein.

            (1) Additional Rent: All sums in addition to Term Basic Rent payable
by Lessee to Lessor pursuant to the provisions of this Lease.

            (2) Base Period Costs: As to the following:

                  (A) Base Operating Costs: Those costs incurred during Calendar
            Year 1998, exclusive of extraordinary or one-time costs, except to
            the extent such extraordinary or one-time costs would be included
            in Operating Costs for a Comparison Period.

                  (B) Base Real Estate Taxes: Those Real Estate Taxes incurred
            for the Building and Office Building Area during Calendar Year 1998.

                  (C) Base Utility and Energy Costs: Those utility and energy
            costs incurred for the Building and Office Building Area during
            Calendar Year 1998 (herein "Base Utility Rate").

            (3) Brokers: NEWMARK PARTNERS, INC. ("Newmark") and CB COMMERCIAL
REAL ESTATE GROUP, INC. ("CB").
<PAGE>

            (4) Building: The building located at 10 Knightsbridge Road (a/k/a
860 Centennial Avenue), Piscataway, New Jersey.

            (5) Building Holidays: Those shown on Exhibit D.

            (6) Demised Premises or Premises: The parties agree that the demised
premises for the purpose of this lease is as shown on Exhibit A hereto. The
parties agree that the area thereof which includes an allocable share of the
Common Facilities as defined in Subsection 40(B) shall be (the "Premises Area")
15,179 gross rentable square fee.

            (7) Expiration Date: At 11:59 p.m. on November 30, 2008.

            (8) Exhibits: The following Exhibits attached to this Lease are
incorporated herein and made a part hereof:

                Exhibit A       Premises

                Exhibit A-1     Office Building Area

                Exhibit B       Rules and Regulations

                Exhibit C       Cleaning Services

                Exhibit D       Building Holidays

                Exhibit E       Lessee Improvement Work

                Exhibit E-1     Removable Improvements

                Exhibit F       Lessor's Environmental Reports

                Exhibit G       Form of Subordination, Non-Disturbance and
                                Attornment Agreement

                Exhibit H       Roof Warranties Currently in Effect

                Exhibit I       Building System Warranties Currently in Effect

            (9) Rent Commencement Date: December 1, 1998

            (10) Term Basic Rent: Two Million Six Hundred Ten Thousand Seven
Hundred Ninety and 00/100 ($2,610,790) Dollars for the Term payable as follows:

                                       2
<PAGE>

--------------------------------------------------------------------------------
                                                   Annual          Monthly
                Period                           Basic Rent      Basic Rent
--------------------------------------------------------------------------------
Rent Commencement Date through the              $242,864.00     $20,238.67
expiration of the 60th month following the
Rent Commencement Date
--------------------------------------------------------------------------------
The fifth anniversary of the Rent               $279,294.00     $23,274.50
Commencement Date through the expiration
of the 120th month following the Rent
Commencement Date.
--------------------------------------------------------------------------------

            (11) Lessee's Percentage: The fraction whose numerator is the
Premises Area and denominator is 64,871.036, subject to adjustment as provided
for in Subsection 40(A).

            (12) Office Building Area: Lot 1A, Block 501A, on the tax map of the
Township of Piscataway, Middlesex County, New Jersey.

            (13) Parking Spaces: A total of sixty-one (61) spaces, all of which
shall be unassigned.

            (14) Permitted Uses: Pharmaceutical research and development
laboratory, general business offices uses and related activities by Lessee, any
division thereof which is not a separate legal entity, or any permitted assignee
or subtenant as herein provided, including Provid Research, the drug discovery,
chemistry division of Lessee.

            (15) Term: Commencing on the date hereof and expiring ten (10) years
from the Rent Commencement Date unless extended pursuant to the renewal option
contained in Paragraph 50 hereof or terminated early due to a casualty or
condemnation or pursuant to the early termination option contained in Paragraph
52 hereof.

                                   WITNESSETH:

            For and in consideration of the covenants herein contained, and upon
the terms and conditions herein set forth, Lessor and Lessee agree as follows:

1. DESCRIPTION. Lessor hereby leases to Lessee, and Lessee hereby hires from
Lessor, the Demised Premises as defined in the Preamble (hereinafter called
"Demised Premises" or "Premises") which includes an allocable share of the
Common Facilities, as shown on the plan or plans, initialed by the parties
hereto, marked Exhibit A attached hereto, and made part of this Lease in the
Building as defined in the Preamble (hereinafter called the "Building"), which
is situated on the Office Building Area as defined in the Preamble (hereinafter
called "Office Building Area") as described on Exhibit A-1 attached hereto and
made part of this Lease,

                                       3
<PAGE>

together with the right to use in common with other Lessees of the Building,
their invitees, customers and employees, those public areas of the Common
Facilities as hereinafter defined.

2. TERM. The Premises are leased for the Term as defined in the Preamble.

3. BASIC RENT. The Lessee shall pay to Lessor during the Term the Term Basic
Rent as defined in the Preamble (hereinafter called "Term Basic Rent"), payable
in such coin or currency of the United States of America as at the time of
payment shall be legal tender for the payment of public and private debts. The
Term Basic Rent shall accrue at the Annual Basic Rent rate (as defined in the
Preamble) and shall be payable in advance on the first day of each calendar
month during the Term in monthly installments of Monthly Basic Rent as defined
in the Preamble. Lessee shall pay Basic Rent, and any Additional Rent as
hereinafter provided, to Lessor at Lessor's above stated address, or at such
other place as Lessor may designate in writing, without demand and without
counterclaim, deduction or setoff, except as expressly provided in this Lease.
As used in this Lease, Basic Rent shall mean either Term Basic Rent, Annual
Basic Rent or Monthly Basic Rent, as appropriate. Anything contained herein to
the contrary notwithstanding, no Term Basic Rent or the Additional Rent
described in Section 22 of this Lease shall be due or payable with respect to
any period prior to the Rent Commencement Date; it being agreed and understood,
however, that during such period, Lessee shall pay all other Additional Rent
which shall be due and payable pursuant to this Lease.

4. USE AND OCCUPANCY. Lessee shall use and occupy the Premises for the Permitted
Uses as defined in the Preamble and for no other purpose.

5. CARE AND REPAIR OF PREMISES/ENVIRONMENTAL.

            (A)   Lessee covenants to commit no act of waste and to take good
                  care of the Premises and the fixtures and appurtenances
                  thereon, and shall, in the use and occupancy of the Premises
                  comply with all laws, orders and regulations of the federal,
                  state and municipal governments or any of their departments
                  affecting the Premises. Lessee shall also comply with any and
                  all environmental requirements resulting from the Lessee's use
                  of the Premises; this covenant to survive the expiration or
                  sooner termination of the Lease. Notwithstanding the
                  foregoing, provided Lessee is not in continuing default under
                  this Lease beyond any notice and cure period and provided such
                  is not prohibited under any mortgage or ground lease
                  encumbering the Premises, Lessee shall have the right, at
                  Lessee's expense, to contest the applicability or validity, in
                  whole or in part, of any laws, codes, rules or regulations
                  with which Lessee shall be required to comply hereunder and,
                  so long as such proceeding is being conducted in good faith,
                  with due diligence and in compliance with the requirements of
                  any mortgage or ground lease encumbering the Premises (of
                  which requirements Lessor shall have given Lessee written
                  notice or, at Lessor's

                                       4
<PAGE>

                  election, Lessor may provide Lessee with a copy of such
                  Mortgage or ground lease), Lessee may defer compliance
                  therewith pending the outcome of the contest, provided that
                  such deferral shall (i) not result in any deprivation in the
                  use of the Premises or the Building by any party entitled
                  thereto; (ii) not result in any civil or criminal liability on
                  the part of the Lessor or (iii) be completed at least 180 days
                  prior to the expiration of the term. Lessee hereby agreeing to
                  indemnify and hold the Lessor harmless from and against any
                  and all losses, costs, claims or expenses arising out of or
                  from such liability. Lessor shall, upon request by Lessee,
                  reasonably cooperate with such contest provided that Lessee
                  shall pay all costs incurred by Lessee in connection
                  therewith. Notwithstanding anything to the contrary contained
                  in this Lease, Lessor and Lessee agree that responsibility for
                  compliance with the Americans with Disabilities Act of 1990,
                  as the same may be amended or supplemented from time to time,
                  or any successor statute and related laws, rules and
                  regulations ("ADA") shall be allocated as follows: (i) Lessor
                  shall be responsible for compliance with the provisions of ADA
                  for all Common Facilities, exterior areas of the Building and
                  any common areas within the Building (excluding Lessee
                  Improvement Work); and (ii) Lessee shall be responsible for
                  compliance with the provisions of ADA within the Premises and
                  for all Lessee Improvement Work within or outside of the
                  Premises.

            (B)   Except for any repairs, maintenance or replacements
                  necessitated by the act(s) or omission(s) of Lessor, its
                  agents, servants, employees or contractors during the Term,
                  Lessee shall, at its sole cost and expense, make all necessary
                  non-structural repairs to the Premises and Lessee Improvement
                  Work. Lessee's obligation to repair shall not extend to
                  repairs that are necessitated by a requirement to comply with
                  laws that are the Lessor's obligation(s). Lessor shall keep in
                  good order and condition, and shall make all necessary repairs
                  to the Common Facilities, to include the structural portions
                  of the Building (including the roof, common areas, exterior
                  walls and exterior windows), to the parking areas, and to the
                  Building systems (including the heating, ventilating and air
                  conditioning, electrical and plumbing lines and systems,
                  except that Lessor shall not be responsible for maintaining or
                  repairing any Lessee Improvement Work, including, but not
                  limited to any separate split system HVAC system (the "Split
                  System") installed by Lessee to service all or a portion of
                  the Premises). In the event that Lessee installs a Split
                  System to service the Premises, Lessee shall (i) during the
                  Term enter into and pay for a service/labor contract with an
                  air conditioning and heating contractor reasonably acceptable
                  to Lessor, and (ii) deliver to Lessor copies of all warranties
                  covering such Split System and related work and, upon
                  termination of this Lease, assign such unexpired warranties to
                  Lessor. Notwithstanding

                                       5
<PAGE>

                  the foregoing, the cost of all such repairs by Lessor shall be
                  included, subject to the other terms and conditions of this
                  Lease, as an Operating Cost (as defined in Paragraph 22A).
                  Lessor will not be responsible for making a repair to any
                  system or any utilities installed by Lessee, unless the repair
                  is necessitated by Lessor's or Lessor's agent's, servant's,
                  visitor's, employee's or licensee's negligence or willful
                  misconduct. Where a repair required to be made by Lessor has
                  been made necessary by misuse or neglect by Lessee or Lessee's
                  agents, servants, visitors or licensees, Lessor shall
                  nevertheless make the repair, but Lessee shall pay to Lessor,
                  as Additional Rent, within thirty (30) days of demand, the
                  reasonable cost therefor.

            (C)   All improvements made by Lessee to the Premises or Building
                  (exclusive of any previously existing improvements located at
                  the Building which are incorporated in those improvements made
                  by Lessee to the Premises or Building), which are so attached
                  to the Premises or Building that they cannot be removed
                  without material injury to the Premises or Building
                  (including, but not limited to the Split System), shall become
                  the property of Lessor upon expiration or earlier termination
                  of the Lease, whether paid for in whole or in part by Lessee,
                  and except for those improvements and alterations specifically
                  identified as such on Exhibit E-1 hereto (the "Removable
                  Improvements") shall be and remain a part of the Premises and
                  Building and the property of Lessor. Not later than the last
                  day of the Term, Lessee shall, at Lessee's sole cost and
                  expense, (i) remove all Lessee's personal property, the
                  Removable Improvements and those improvements made by Lessee
                  which do not become the property of Lessor as aforesaid,
                  including trade fixtures, movable paneling, movable partitions
                  and the like; (ii) repair all injury done by or in connection
                  with the installation or removal of said property and
                  improvements (if any); and (iii) surrender the Premises in at
                  least as good condition as they were at the beginning of the
                  Term, reasonable wear and tear and damage by fire or other
                  casualty (other than that caused by the willful or unlawful
                  misconduct of Lessee or Lessee's agents, employees or
                  visitors) excepted. Notwithstanding anything to the contrary
                  contained in this Lease, Lessee shall not be required, at or
                  prior to the expiration or earlier termination of this Lease,
                  to remove (i) computer access floors, standard construction
                  partitions and standard ceilings; or (ii) pipes, wires,
                  cables, conduit or the like from walls, ceilings or floors,
                  provided that Lessee properly cuts, caps and disconnects same
                  in a safe and lawful manner, flush with the applicable floor,
                  wall or ceiling. Except as otherwise agreed upon in a writing
                  signed by both Lessor and Lessee, all other property of Lessee
                  remaining on the Premises after the last day of the Term of
                  this Lease shall be conclusively deemed abandoned and may be
                  removed by Lessor, and

                                       6
<PAGE>

                  Lessee shall reimburse Lessor for the reasonable cost of such
                  removal. Lessor may have any such property stored at Lessee's
                  risk and reasonable expense.

            (D)

                  (i)   In the event that Lessee is required to comply with the
                        New Jersey Industrial Site Recovery Act, N.J.S.A.
                        13:1K-6 et. seq. and its implementing regulations
                        ("ISRA") because Lessee's operation at the Demised
                        Premises is an "industrial establishment" as defined by
                        ISRA, and if Lessee plans to change operations at the
                        Demised Premises, or plans to transfer ownership or
                        operations of the Demised Premises or closes its
                        operations at the Demised Premises and such action would
                        trigger the requirements of the ISRA, Lessee shall be
                        responsible for taking all actions to comply with the
                        ISRA, including, without limitation, filing all notices
                        and forms and undertaking all investigations and
                        remedial actions as required in order to complete the
                        ISRA process. Lessee shall provide copies of all its
                        submissions to the New Jersey Department of
                        Environmental Protection ("DEP") and all correspondence
                        received from the DEP to Lessor. Lessor agrees that it
                        will reasonably cooperate with Lessee's compliance with
                        ISRA hereunder, including, but not limited to, providing
                        documents and other information needed by Lessee to
                        complete forms and conduct investigations and executing
                        (to the extent necessary) any forms required by the ISRA
                        process.

                  (ii)  Except as provided in the next sentence, Lessee shall be
                        responsible for all costs and expenses it incurs with
                        respect to compliance with ISRA to the extent that ISRA
                        has been triggered whether by current operation or as a
                        result of Lessee's change in operation, transfer of
                        ownership or operations or closing of operations. To the
                        extent that Lessee is required to undertake any field
                        sampling to investigate an area of concern and/or is
                        required to remediate any area of concern in connection
                        with the Demised Premises, and such area of concern is
                        an area of concern solely because of environmental
                        conditions that pre-date Lessee's occupancy of the
                        Demised Premises, or cause of actions or omissions of
                        persons other than Lessee or the employees, agents,
                        contractors or invitees of Lessee, Lessee shall not be
                        responsible for the investigation and remediation of
                        such areas and, in the event that such area of concern
                        is an area of concern solely because of environmental
                        conditions that predate Lessee's occupancy of the Demise
                        Premises or

                                       7
<PAGE>

                        because of any acts or omissions of Lessor, its agents,
                        representatives or contractors, then Lessor shall
                        reimburse Lessee for the reasonable costs and expenses
                        incurred by Lessee for the investigation and remediation
                        of such areas.

                  (iii) If Lessor: (a) transfers ownership or operations of the
                        Demised Premises or the property that includes the
                        Demised Premises; or (b) closes its operations at the
                        Demised Premises or the property that includes the
                        Demised Premises, and as a result thereof triggers the
                        requirements of ISRA, subject to the following proviso,
                        Lessee shall not be responsible for taking any action to
                        comply with ISRA, including, without limitation, filing
                        any notices and forms and undertaking any investigations
                        or remedial actions required in order to complete the
                        ISRA process; provided, however, that Lessee shall be
                        responsible for remediating or otherwise responding to
                        any environmental condition which is caused by the acts
                        or omissions of Lessee or its agents, contractors,
                        representatives or invitees and shall otherwise
                        reasonably cooperate with Lessor as required below.
                        Lessor shall provide copies of Lessor's submissions to
                        the DEP and correspondence received from the DEP to
                        Lessee which relate in any part to the Demised Premises.
                        Lessee agrees that in the event that Lessor may be
                        required to comply with ISRA, Lessee will reasonably
                        cooperate with Lessor's compliance, including, but not
                        limited to, providing documents and other information
                        needed by Lessor to complete forms and conduct
                        investigations, and executing (to the extent necessary)
                        any forms required by the ISRA process. Except as
                        provided in the next sentence, Lessor shall be
                        responsible for all costs and expenses it incurs with
                        respect to compliance with ISRA to the extent that ISRA
                        has been triggered solely as a result of Lessor's
                        transfer of ownership or operations or closing of
                        operations. To the extent that Lessor is required to
                        undertake any field sampling to investigate an area of
                        concern and/or is required to remediate any area of
                        concern in connection with the Demised Premises, and
                        such area of concern is an area of concern primarily
                        because of environmental conditions caused by the
                        actions or omissions of Lessee or the employees, agents,
                        contractors or invitees of Lessee, Lessee shall
                        indemnify and reimburse Lessor for all reasonable costs
                        and expenses incurred by Lessee with respect to the
                        investigation and remediation of such areas.

                  (iv)  In the event Lessee fails to comply with ISRA as stated
                        in this Subsection 5(D), and as a consequence thereof,
                        Lessor, as a matter

                                       8
<PAGE>

                        of law, is unable to rent the Demised Premises, then the
                        Lessor shall treat the Lessee as one who has not removed
                        at the end of its Term, and thereupon be entitled to all
                        remedies against the Lessee provided by law in that
                        situation including a monthly rental as set forth in
                        Section 24 hereof, until such time as Lessee provides
                        Lessor with a negative declaration or confirmation that
                        any required clean-up plan has been successfully
                        completed.

            (E)   As used herein, Hazardous Substances shall be defined as any
                  hazardous chemical, hazardous substance, or hazardous or toxic
                  material, waste, pollutants or contaminants, asbestos or
                  petroleum or petroleum related substance or similar terms as
                  defined in The Comprehensive Environmental Responsibility
                  Compensation and Liability Act, as amended (42 U.S.C. 9601, et
                  seq.), the New Jersey Environmental Cleanup Act, as amended
                  and/or ISRA, the New Jersey Spill Compensation and Control
                  Act, as amended, N.J.S.A. 58:10-23.11b, et seq., any rules or
                  regulations promulgated thereunder, or in any other applicable
                  federal, state or local law, rule or regulation dealing with
                  environmental protection ("Environmental Laws"). It is
                  understood and agreed that the provisions contained in this
                  Section 5 shall be applicable notwithstanding the fact that
                  any substance shall not be deemed to be a Hazardous Substance
                  at the time of its use by the Lessee, but shall thereafter be
                  deemed to be a Hazardous Substance.

            (F)

                  (i)   Lessee shall comply in all material respects with all
                        applicable Environmental Laws with respect to its
                        occupancy and operations at the Demised Premises,
                        including, without limitation, obtaining all required
                        permits, licenses or approvals required pursuant to
                        applicable Environmental Laws with respect to Lessee's
                        occupancy and use of the Demised Premises.

                  (ii)  Lessee shall only handle, use, manufacture, store,
                        process, transport or dispose of Hazardous Substances
                        with respect to its occupancy and operations at the
                        Demised Premises that are reasonably necessary and
                        useful in Lessee's business and operations. The amount
                        of Hazardous Substances that are maintained at the
                        Demised Premises at any one time shall only be that
                        amount of Hazardous Substances that are reasonably
                        necessary in connection with Lessee's business and
                        operations. Notwithstanding the foregoing, Lessee shall
                        only handle, use, manufacture, store, process, transport
                        or dispose of Hazardous Substances in material
                        compliance with all applicable Environmental Laws.

                                       9
<PAGE>

                  (iii) Lessee agrees that it shall provide to Lessor, upon
                        Lessor's request, copies of material safety data sheets
                        ("MSDS") (to the extent Lessee is required to have such
                        sheets for a particular Hazardous Substance) with
                        respect to any Hazardous Substance that is used by
                        Lessee. Lessee shall provide such MSDS to Lessor within
                        thirty (30) days of Lessor's request.

                  (iv)  Lessee shall use all reasonable efforts to ensure that
                        its operations do not result in environmental
                        contamination of the Demised Premises and/or Office
                        Building Area and that it will comply with all
                        applicable Environmental Laws relating to the
                        investigation and remediation of environmental
                        contamination in the event that its operations do cause
                        such contamination or potential contamination.

                  (v)   Lessee shall conduct its operations so that it will not
                        be required to obtain a permit with respect to the
                        treatment, storage and disposal of hazardous waste
                        pursuant to the Federal Resource Conservation and
                        Recovery Act of 1976, as amended, or the analogous New
                        Jersey statute regulating the management of hazardous
                        waste. Lessee shall agree not to install any regulated
                        underground storage tank at the Demised Premises and/or
                        Office Building Area without the express written consent
                        of Lessor, which consent may be withheld for any reason
                        or no reason.

                  (vi)  In performing any alterations to the Demised Premises
                        and/or Building permitted by this Lease, Lessee shall
                        not incorporate any Hazardous Substances into the
                        physical structure of the Demised Premises and/or
                        Building without the express written consent of Lessor,
                        such consent not to be unreasonably withheld.

            (G)   Lessor represents that based solely upon the contents of those
                  certain reports identified on Exhibit F hereto, except as set
                  forth in those certain reports identified on Exhibit F hereto
                  (which Lessee acknowledges having received and reviewed):

                  (i)   There have been no releases (as defined by the
                        Comprehensive Environmental Response, Compensation and
                        Liability Act of 1980, as amended) of Hazardous
                        Substances at the Demised Premises, except for releases
                        that have been investigated and/or remediated pursuant
                        to applicable Environmental Laws and as to which Lessor
                        (or such other party as was responsible for the release)
                        has obtained a no further action letter or negative
                        declaration from the

                                       10
<PAGE>

                        DEP or the United States Environmental Protection Agency
                        ("EPA").

                  (ii)  There have been no filings, proceedings, investigations
                        or remedial actions conducted with respect to the
                        Demised Premises or the property containing the Demised
                        Premises pursuant to ISRA, or its predecessor, the
                        Environmental Cleanup Responsibility Act ("ECRA").

                  (iii) The Demised Premises do not contain any friable or
                        non-friable asbestos-containing material; electrical
                        equipment containing polychlorinated biphenyls; urea
                        formaldehyde insulation; underground storage tanks, or
                        septic systems.

            (H)   If Lessor, in its sole discretion, believes that the Demised
                  Premises or the environment may have become contaminated with
                  Hazardous Substances that must be reported, investigated,
                  removed, remediated or otherwise responded to, Lessor, in
                  addition to its other rights under this Lease, may enter upon
                  the Demised Premises and obtain samples from the Demised
                  Premises, including without limitation, the soil and
                  groundwater under the Demised Premises, for the purposes of
                  analyzing the same to determine whether and to what extent the
                  Demised Premises or the environment have become so
                  contaminated, provided that (i) Lessor shall provide Lessee
                  with reasonable notice of its intent to enter the Demised
                  Premises and conduct any inspection, including, but not
                  limited to, its intent to obtain samples, which notice shall
                  (except in the case of emergencies) be provided to Lessee at
                  least five (5) business days prior to the date of the intended
                  inspection; (ii) except in the case of an emergency, such
                  inspections shall be conducted during normal business hours
                  unless Lessee authorizes Lessor to make such inspections at
                  other hours; (iii) such inspections shall minimize, to the
                  greatest extent possible, any disruption to Lessee's
                  operations, which (except in the case of an emergency) shall
                  include rescheduling any such inspection at the reasonable
                  request of Lessee; (iv) such inspections shall not require
                  Lessee to reveal any confidential or proprietary information
                  related to Lessee's business or operations; (v) such
                  inspections shall be conducted at the sole cost and expense of
                  Lessor (subject to any other right of indemnification provided
                  pursuant to this Lease); (vi) Lessee shall have the right to
                  have its employees and representatives (including, but not
                  limited to, attorneys and environmental consultants) present
                  during the inspection, provided that such right does not
                  unreasonably interfere with Lessor's scheduling of such
                  inspection; (vii) Lessee shall have the right to collect (at
                  its own cost and expense) split samples; and (viii) Lessor
                  shall promptly provide copies

                                       11
<PAGE>

                  of all reports, analyses and data with respect to the
                  inspection to Lessee, which Lessee agrees to keep
                  confidential, unless compelled to disclose such information by
                  a court or regulatory agency with jurisdiction over the
                  Demised Premises. Lessee may not perform any sampling,
                  testing, or drilling to locate any Hazardous Substances on, in
                  or about the Demised Premises without Lessor's prior written
                  consent, such consent not to be unreasonably withheld, except
                  that if Lessee is obligated to conduct sampling, testing or
                  drilling pursuant to ISRA or another applicable Environmental
                  Law, Lessee may do so only after delivering at least five (5)
                  days prior written notice to Lessor.

            (I)

                  (i)   In addition to any other indemnity contained in this
                        Lease, Lessee agrees to indemnify and hold harmless the
                        Lessor from and against any and all liabilities,
                        damages, claims, losses, judgments, causes of action,
                        fine, penalty costs and expenses (including the
                        reasonable fees and expenses of counsel, including costs
                        of reporting, investigation, remediation or other
                        response action) (collectively, "Environmental Damage")
                        which may be incurred by the Lessor or threatened
                        against the Lessor relating to or arising out of (a)
                        Lessee's failure to comply with applicable Environmental
                        Laws; (b) the release or disposal of Hazardous
                        Substances on or from the Demised Premises and/or Office
                        Building Area by Lessee or Lessee's employees, agents,
                        contractors, or invitees; or (c) Lessee's failure to
                        comply with covenants hereunder that relate to its use
                        and handling of Hazardous Substances or its compliance
                        with applicable Environmental Laws.

                  (ii)  In addition to any other indemnity contained in this
                        Lease, Lessor agrees to defend, indemnify and hold
                        harmless the Lessee from and against all
                        Environmental Damages which may be incurred by
                        Lessee or threatened against Lessee relating to or
                        arising out of (a) Lessor's failure to comply with
                        applicable Environmental Laws, or (b) the release or
                        disposal of Hazardous Substances on or from the
                        Demised Premises or the property containing the
                        Demised Premises which occurred prior to Lessee's
                        occupancy of the Demised Premises or was otherwise
                        caused by the acts or omissions of Lessor, its agents,
                        representatives or contractors.

                  (iii) To the extent that any Environmental Damages are a
                        result of conditions that are covered by subsections
                        I(i) and I(ii) above, the parties' respective
                        obligations pursuant to this Section 5 shall be

                                       12
<PAGE>

                        allocated comparatively, by taking into account the
                        amount and toxicity of the Hazardous Substances that
                        would be deemed the responsibility of Lessee pursuant to
                        subsection I(i) above or Lessor pursuant to subsection
                        I(ii) above, as well as the culpability of the parties
                        with respect to the condition requiring investigation or
                        remediation.

            (J)   Lessee shall provide to the Lessor for review and comment
                  copies of any documents that would be submitted to third
                  parties (including governmental bodies) regarding any material
                  environmental issues. Lessor shall provide its comments to
                  Lessee within five (5) business days after delivery of such
                  documents. For any matter where Lessor has an obligation to
                  defend, indemnify or hold harmless the Lessee under this
                  section, Lessee shall not be required to incur any cost or
                  expense, unless such cost or expense relates to an activity in
                  which Lessee is directed to engage by a regulatory agency or a
                  court.

            (K)   The covenants and agreements of Sections 5(D) through 5(J)
                  inclusive shall survive the termination or sooner expiration
                  of the Lease and surrender of the Demised Premises by Lessee
                  and shall also survive the sale, lease or assignment of the
                  Demised Premises (or property upon which the Demised Premises
                  is located) by Lessor.

6. ALTERATIONS, ADDITIONS OR IMPROVEMENTS.

            (A)   Except as otherwise provided herein, Lessee shall not, without
                  first obtaining the written consent of Lessor, make any
                  alterations, additions or improvements in, to or about the
                  Premises and/or Building. Except for alterations, additions or
                  improvements which affect the structural components or roof of
                  the Building or any of the Building's mechanical, heating,
                  ventilating, air conditioning, plumbing, electrical or other
                  systems, Lessor shall not unreasonably withhold or delay its
                  consent to any alteration, addition or improvement to the
                  Demised Premises. As a condition to Lessor consenting to any
                  alteration, addition or improvement to be made by Lessee which
                  will affect (i) the Building's roof, Lessee shall provide
                  Lessor with, among other things reasonably requested by
                  Lessor, documentary evidence stating that Lessee's proposed
                  work will not render any roof warranty which Lessor has
                  furnished to Lessee void or voidable (Lessor acknowledging
                  that Exhibit H lists the roof warranties currently in effect);
                  or (ii) the Building's mechanical, heating, ventilating, air
                  conditioning, plumbing, electrical or other systems, Lessee
                  shall, among other things reasonably requested by Lessor, (a)
                  provide Lessor which plans signed and sealed by CUH2A, Inc. or
                  another engineering firm,

                                       13
<PAGE>

                  reasonably acceptable to Lessor (with experience in the design
                  of the type of Building system to be altered by Lessee),
                  indicating the scope of the work to be performed; Lessor
                  hereby agreeing that the provision of such Building services
                  to any other tenant in the Building will not be materially
                  diminished following completion of such work; unless Lessor
                  obtains approval from any affected tenant, and (b) provide
                  Lessor with documentary evidence stating that Lessee's
                  proposed work will not render any applicable Building system
                  warranty which Lessor has furnished to Lessee void or voidable
                  (Lessor acknowledging that Exhibit I lists the Building system
                  warranties currently in effect). Prior to commencing any
                  alterations, additions or improvements which may interrupt the
                  Building Services to other tenants, Lessee shall enter into a
                  written agreement with Lessor and all other tenants then
                  occupying the Building, in form and content reasonably
                  acceptable to Lessor and acceptable to such other tenants,
                  setting forth the dates and times when Lessee's proposed work
                  may interrupt the Building Services to such other tenants and
                  whereby such other tenants consent to the scheduled
                  interruptions. Any approval granted, or any agreement entered
                  into, by Lessor hereunder shall not be deemed to be a
                  certification by Lessor that the work to be performed by
                  Lessee will not interfere with or materially diminish the
                  affected Building services provided to the other Building
                  tenants. Any alterations, additions or improvements approved
                  by Lessor, shall be performed by Lessee, at its sole cost and
                  expense, using reputable licensed contractors and
                  subcontractors approved by Lessor, which approval shall not be
                  unreasonably withheld or delayed.

            (B)   All such alteration, addition or improvement work shall be
                  performed in a good and workmanlike manner using new materials
                  or materials of a quality consistent with first-class work of
                  similar type to the Lessee Improvement Work and in compliance
                  with all applicable statutes, laws, codes, rules, regulations
                  and requirements of all governmental and quasi-governmental
                  authorities having jurisdiction thereof and all requirements
                  of any mortgage or ground lease encumbering the Premises or
                  the insurer(s) insuring the Building (of which requirements
                  Lessor shall have given Lessee written notice or, at Lessor's
                  election, Lessor may provide Lessee with a copy of such
                  Mortgage or ground lease). Prior to performing any such
                  alteration, addition or improvement work, Lessee or its
                  contractor(s) shall obtain, at Lessee's sole cost and expense,
                  all necessary governmental and quasi-governmental permits,
                  approvals, certificates and authorizations relating to such
                  work and shall deliver copies thereof to Lessor. Upon
                  completion of any alteration, addition or improvement work,
                  Lessee shall promptly obtain, at its sole cost and expense,
                  and deliver to Lessee a copy of all required governmental and

                                       14
<PAGE>

                  quasi-governmental certificates and/or sign-offs evidencing
                  such completion. Notwithstanding anything to the contrary
                  contained in this Lease, Lessee may make alterations,
                  improvements or additions to the Premises with an aggregate
                  cost within any 12 month period of less than $10,000.00
                  without the consent of Lessor being first obtained; provided,
                  however, that any such alterations, improvements or additions
                  (i) shall be made in a good and workmanlike manner; (ii) shall
                  be made in accordance with all of the other terms and
                  conditions of this Lease; (iii) shall not affect any areas of
                  the Building other than the Premises; (iv) are not prohibited
                  by any mortgage or ground Lease as aforesaid; and (v) do not
                  affect any structural elements of the Building or Building
                  systems.

            (C)   Lessor agrees that at no expense to Lessor, it will, to the
                  extent reasonably necessary, (i) execute applications required
                  by the local planning board and similar authorities, and (ii)
                  otherwise reasonably cooperation with Lessee, in connection
                  with Lessee obtaining the required governmental or
                  quasi-governmental approval of the Lessee Improvement Work and
                  challenging any applicable laws which threaten to prevent the
                  Premises from being used for the Permitted Use.

7. ASSIGNMENT AND SUBLEASE. Lessee may not mortgage, pledge, hypothecate,
assign, transfer or sublet this Lease or the Premises in any manner except as
specifically provided for in this Section 7:

            (A)   Lessee may assign this Lease or sublet the whole or any
                  portion of the Premises (including, but not limited to, an
                  assignment of this Lease made in connection with a spin-off
                  of the Provid Research division of Lessee, provided that
                  Lessee remains primarily liable under this Lease and the
                  Provid Research division's operations continue at the Demised
                  Premises), subject to Lessor's prior written consent, which
                  consent shall not be unreasonably withheld or delayed.  All
                  assignments of this Lease or any sublease of the whole or any
                  portion of the Demised Premises (regardless of whether
                  Lessor's consent is required) shall be on the basis of the
                  following terms and conditions:

                  (i)   The Lessee shall provide to Lessor the name and address
                        of the assignee or sub-lessee.

                  (ii)  The assignee shall assume by written instrument all of
                        the obligations of this Lease or any subtenant shall
                        take subject to all of the obligations of this Lease,
                        and a copy of such assumption agreement or sublease, as
                        applicable, shall be furnished to Lessor together with
                        Lessee's written request for Lessor's consent, which

                                       15
<PAGE>

                        consent shall be granted or denied (with reasons for
                        such denial), within twenty (20) days after receipt of
                        Lessee's request therefor.

                  (iii) The Lessee and each assignee shall be and remain liable
                        for the observance of all of the covenants and
                        provisions of this Lease, including, but not limited to,
                        the payment of Term Basic Rent and Additional Rent
                        reserved herein, as and when required to be paid,
                        through the entire Term of this Lease, as the same may
                        be renewed, extended or otherwise modified if at all and
                        each subtenant shall take subject to all of the
                        covenants and provisions of this Lease, as the same
                        shall be renewed, extended or otherwise modified if at
                        all.

                  (iv)  The acceptance by Lessor of any Basic Rent and/or
                        Additional Rent from the assignee or from any of the
                        subtenants or the failure of Lessor insist upon a strict
                        performance of any of the terms, conditions and
                        covenants herein shall not release Lessee herein, nor
                        any such assignee or subtenant, from any and all of the
                        obligations herein during and for the entire Term of
                        this Lease.

                  (v)   Lessee shall reimburse Lessor for its reasonable
                        out-of-pocket expenses, incurred for reviewing and
                        processing each request for consent to any sublet or
                        assignment (including, but not limited to, reasonable
                        attorney's fees).

                  (vi)  Lessee shall have no claim, and hereby waives the right
                        to any claim, against Lessor money damages by reason of
                        any refusal, withholding or delaying by Lessor of any
                        consent, and in such event, Lessee's only remedies
                        therefor shall be an action for specific performance,
                        injunction or declaratory judgment to enforce any such
                        requirement.

            (B)   If Lessor shall give its consent to any assignment of this
                  Lease or to any sublease, Lessee shall in consideration
                  therefor, pay to Lessor, as Additional Rent, fifty (50%)
                  percent of the Assignment Profits or the Sublease Profits, as
                  the case may be:

                  (i)   "Assignment Profits" shall mean the amount by which all
                        sums and other considerations paid to Lessee by the
                        assignee for or by reason of such assignment exceeds the
                        brokerage commissions actually paid by Lessee in
                        connection with such assignment and other expenses
                        reasonably incurred by Lessee in connection with such
                        assignment for which Lessee provides reasonably
                        satisfactory evidence thereof to Lessor (including,
                        without limitation,

                                       16
<PAGE>

                        reasonable legal fees and disbursements directly
                        incurred in connection with such assignment, improvement
                        allowances and other cash concessions (including
                        so-called "free rent") paid by Lessee, advertising
                        expenses, construction expenses, architectural and
                        planning expenses, any expenses payable to Lessor with
                        respect to the assignment or sublet (including without
                        limitation any payments paid or payable pursuant to
                        Section 7(A)(v) hereof), permitting and licensing costs
                        and lease takeover payments). Assignment Profits shall
                        exclude sums paid by the assignee for any Lessee's
                        personal property, equipment, and trade fixtures unless
                        the payment of such sums constitute a subterfuge to
                        avoid legitimate inclusion in the above-described
                        computation of Assignment Profits. The sums payable
                        under this Subsection B(i) shall be paid to Lessor as
                        and when paid by assignee to Lessee.

                  (ii)  "Sublease Profits" shall mean the amount by which any
                        rents, additional charges or other consideration paid by
                        the sub-lessee to the Lessee in respect of the sublet
                        premises exceeds the sum of (1) the Annual Basic Rent
                        and Additional Rent accruing during the term of the
                        sublease in respect of the sublet premises (at the rate
                        per rentable square foot payable by Lessee hereunder),
                        (2) brokerage commissions actually paid by Lessee in
                        connection with the sublease (amortized over the term of
                        the sublease), (3) the unamortized portion (computed on
                        a straight-line basis over the term of the sublease in
                        accordance with generally accepted accounting principles
                        consistently applied) of the bona fide cost of (x) the
                        Lessee Improvement Work (net of the amount of the Lessee
                        Allowance) and (y) the alterations made by Lessee in
                        preparing the subleased space, and (4) other expenses
                        reasonably incurred by Lessee in connection with the
                        sublease for which Lessee provides satisfactory evidence
                        thereof to Lessor, amortized over the term of the
                        sublease (including without limitation, reasonable legal
                        fees and disbursements directly incurred in connection
                        with such sublease, improvements allowances and other
                        case concessions paid by Lessee, advertising expenses,
                        construction expenses, architectural and planning
                        expenses, any expenses payable to Lessor with respect to
                        the assignment or sublet (including without limitation
                        any payments paid or payable pursuant to Section 7(A)(v)
                        hereof), permitting and licensing costs and lease
                        takeover payments). Sublease Profits shall exclude sums
                        paid by the sub-lessee for any of Lessee's personal
                        property, equipment, and trade fixtures unless the
                        payment of such sums constitute a subterfuge to avoid
                        legitimate inclusion in the above-described computation
                        of

                                       17
<PAGE>

                        Sublease Profits. The sums payable under this Subsection
                        B(2) shall be paid to Lessor as and when paid by the
                        sublessee to Lessee. Lessee shall use reasonable efforts
                        to collect from such sublessee all rents, additional
                        charges and other consideration owing to Lessee.

            (C)   Any sublet or assignment to an affiliated company shall not
                  require Lessor's prior written consent, but shall require
                  Lessee to deliver to Lessor at least fifteen (15) days prior
                  written notice of such assignment or sublease and all other
                  provisions of this Section, other than Sections 7(A)(ii), (v)
                  and 7(B), shall apply. As used herein, "affiliated company"
                  shall mean any corporation or other business entity which
                  controls, is controlled by, or is under common control with,
                  Lessee at the time of such assignment or subletting and at all
                  subsequent times that such party is in occupancy of the
                  Premises. For the purposes hereof, "control" shall be deemed
                  to mean with respect to a corporation, ownership of more than
                  50% of all of the voting stock of such corporation and with
                  respect to a partnership or other entity, the ownership of
                  more than 50% of all the legal and equitable interests in such
                  partnership or any other entity and the right to control the
                  management and decision-making of such partnership or other
                  entity. Lessee may, without the consent of Lessor, assign or
                  transfer this Lease or sublet the Premises in whole or in part
                  to: (i) a corporation or other entity into which or with which
                  Lessee is merged or consolidated; or (ii) a corporation or
                  other entity acquiring this Lease and all or substantially all
                  of the other property of Lessee and assuming all or
                  substantially all of the liabilities of Lessee; or (iii) a
                  corporation or other entity with which Lessee is or may become
                  affiliated; provided, however, that the same utilize the
                  Premises consistent with the uses provided for herein. In
                  connection with any transactions set forth in clauses (i),
                  (ii) or (iii) of this Section 7(C), Sections 7(A)(ii), (v) and
                  7(B) shall not apply. In addition, Section 7(B) shall not
                  apply with respect to an assignment or sublet relating to
                  Lessee's spin-off of its Provid Research division; provided
                  that Lessee remains primarily liable under this Lease and the
                  Provid Research division's operations continue at the Demised
                  Premises.

            (D)

                  (i)   In the event that any or all of Lessee's interest in the
                        Premises and/or this Lease is transferred by operation
                        of law to any trustee, receiver, or other representative
                        or agent of Lessee pursuant to any state or federal
                        bankruptcy or receivership statute or procedure, or to
                        Lessee as a debtor in possession, and subsequently any
                        or all of Lessee's interest in the Premises and/or this
                        Lease is offered by

                                       18
<PAGE>

                        Lessee or any trustee, receiver, or other representative
                        or agent of Lessee pursuant to any state or federal
                        bankruptcy or receivership statute or procedure, as to
                        its estate or property (such person, firm or entity
                        being hereinafter referred to as the "Grantor"), for
                        assignment, conveyance, lease, or other disposition to a
                        person, firm or entity other than Lessor (each such
                        transaction being hereinafter referred to as a
                        "Disposition"), then, unless prohibited by applicable
                        law, it is agreed that Lessor has and shall have a right
                        of first refusal to purchase, take, or otherwise
                        acquire, the same upon the same terms and conditions as
                        the Grantor thereof shall accept upon such Disposition
                        to such other person, firm, or entity; and as each such
                        Disposition the Grantor shall given written notice to
                        Lessor in reasonable detail of all the terms and
                        conditions of such Disposition within twenty (20) days
                        next following its determination to accept the same but
                        prior to accepting the same, and Grantor, unless
                        prohibited by applicable law, shall not make the
                        Disposition until and unless Lessor has failed or
                        refused to accept such right of first refusal as to the
                        Disposition, as set forth herein.

                  (ii)  Lessor shall have fifteen (15) business days next
                        following its receipt of the written notice as to such
                        Disposition in which to exercise the option to acquire
                        Lessee's interest by such Disposition, and the exercise
                        of the option by Lessor shall be effected by notice to
                        that effect sent to the Grantor; but nothing herein
                        shall require Lessor to accept a particular Disposition
                        or any Disposition, nor does the rejection of any one
                        such offer of first refusal constitute a waiver or
                        release of any one such offer of first refusal
                        constitute a waiver or release of the obligation of the
                        Grantor to submit other offers hereunder to Lessor. In
                        the event Lessor accepts such offer of first refusal,
                        the transaction shall be consummated pursuant to the
                        terms and conditions of the Disposition described in the
                        notice to Lessor. In the event Lessor rejects such offer
                        of first refusal, Grantor may consummate the Disposition
                        with such other person, firm, or entity; but any
                        decrease in the price sought from Lessor or any change
                        in the terms of payment for such Disposition shall
                        constitute a new transaction requiring a further option
                        of first refusal to be given to Lessor hereunder.

            (E)   Without limiting any of the provisions of Sections 11 and 12,
                  if pursuant to the Federal Bankruptcy Code (herein the
                  "Code"), or any similar law hereafter enacted having the same
                  general purpose, Lessor declines the right provided it in
                  Subsection 7(D) hereof and Lessee is permitted to

                                       19
<PAGE>

                  assign this Lease notwithstanding the restrictions contained
                  in this Lease, adequate assurance of future performance by an
                  assignee expressly permitted under such Code shall be deemed
                  to mean the deposit of cash security in an amount equal to one
                  (1) year's Annual Basic Rent and Additional Rent for the next
                  succeeding twelve (12) months (which Additional Rent shall be
                  reasonably estimated by Lessor), which deposit shall be held
                  by Lessor for the balance of the Term, in an interest-bearing
                  account, as security for the full performance of all of
                  Lessee's obligations under this Lease.

            (F)   Except as specifically set forth above, no portion of the
                  Demised Premises or of Lessee's interest in this Lease may be
                  acquired by any other person or entity, whether by assignment,
                  mortgage, sublease, transfer, operation of law or act of the
                  Lessee, nor shall Lessee pledge its interest in this Lease.

8. COMPLIANCE WITH RULES AND REGULATIONS. Lessee shall observe and comply with
the rules and regulations hereinafter set forth in Exhibit B attached hereto and
made a part hereof and with such further reasonable rules and regulations as
Lessor may prescribe, on written notice to Lessee, for the safety, care and
cleanliness of the Building and the comfort, quiet and convenience of other
occupants of the Building. Lessor shall not enforce the rules and regulations in
a discriminatory manner. If there is any inconsistency between the rules and
regulations and the provisions set forth in the body of this Lease, the
provisions set forth in the body of this Lease shall prevail. Lessee shall not
place a load upon any floor of the Demised Premises exceeding the floor load per
square foot area which it was designed to carry (which information shall be
supplied to Lessee upon request, to the extent such information is in Lessor's
possession) and which is allowed by law. Lessor reserves the right to reasonably
prescribe the weight and position of all safes, business machines and mechanical
equipment. Such installations shall be placed and maintained by Lessee, at
Lessee's expense, in settings sufficient, in Lessor's reasonable judgment, to
absorb and prevent vibration, noise and annoyance. In no event shall any rule or
regulation be applicable to Lessee to the extent that such rule or regulation
would materially restrict Lessee's right to use and occupy the Demised Premises
for any of the purposes set forth as a Permitted Use.

9. DAMAGES TO BUILDING/WAIVER OF SUBROGATION.

            (A)   If the Building is damaged by fire or any other cause to such
                  extent that the cost of restoration, as reasonably estimated
                  by Lessor, will equal or exceed twenty-five (25%) percent of
                  the replacement value of the Building (exclusive of
                  foundations) just prior to the occurrence of the damage or if
                  any damage to the Premises costing more that Fifty Thousand
                  and 00/100 ($50,000) Dollars occurs within the last twelve
                  (12) months of the Term, then Lessor (or Lessee with respect
                  to such damage to the Premises within the last 12 months of
                  the Term) may, no later than the sixtieth (60th) day

                                       20
<PAGE>

                  following the damage, give Lessee (or Lessor, as the case may
                  be) a notice of election to terminate this Lease. In said
                  event of election, this Lease shall be deemed to terminate
                  effective on the thirtieth (30th) day after the giving of said
                  notice. Lessee shall surrender possession of the Premises on
                  or before the effective date of termination and the Term Basic
                  Rent and any Additional shall be apportioned as of the date of
                  said termination date, and any Term Basic Rent or any
                  Additional Rent paid for any period beyond the effective
                  termination date shall be repaid to Lessee. If Lessor and
                  Lessee shall not have the right to terminate this Lease as
                  provided in this Section 9, or if, despite Lessor's or
                  Lessee's right to terminate, Lessor nor Lessee elects to
                  terminate this Lease pursuant to any right contained herein,
                  Lessor shall (except as set forth in the following sentence)
                  restore the Building and the Premises with reasonable
                  promptness, subject to Force Majeure, as hereinafter defined
                  and Lessee shall have no right to terminate this Lease, except
                  as specifically set forth in subsection 9(B) below.
                  Notwithstanding the foregoing, if Lessor is required to
                  restore the Building and Premises pursuant to the provisions
                  of this Section 9, Lessee shall, subject to Force Majeure,
                  promptly commence and prosecute restoration of all Lessee
                  Improvement Work, and such other fixtures, improvements or
                  systems owned and/or installed by Lessee, following
                  substantial completion of Lessor's restoration work (or at
                  such earlier time as Lessee and Lessor mutually agree). In
                  addition to all other applicable provisions of this Lease,
                  Lessee's restoration work shall be performed and completed in
                  accordance with the provisions of Sections 6 and 26 hereof.

            (B)   Anything contained in this Section 9 to the contrary
                  notwithstanding, within sixty (60) days after Lessee has given
                  written notice to Lessor of any damage to the Building that
                  materially impairs Lessee's ability to conduct its business in
                  the Premises, Lessor shall deliver to Lessee a statement
                  prepared by a reputable contractor selected by Lessor and
                  reasonably acceptable to Lessee, setting forth such
                  contractor's estimate as to the time required for Lessor to
                  repair such damage to the Building for which Lessor is
                  responsible. If the estimated time period exceeds one hundred
                  eighty (180) days from the date of such damage, Lessee may
                  elect to terminate this Lease by notice to Lessor not later
                  than thirty (30) days following receipt of such statement. If
                  Lessee shall not elect to terminate this Lease as aforesaid
                  (or is not entitled to terminate this Lease pursuant to this
                  Section), then Lessor and Lessee shall restore the Building
                  and the Premises as required herein with reasonable
                  promptness.

            (C)   In the event the Premises shall have been rendered
                  untenantable in whole or part due to damage by fire or other
                  casualty and this Lease shall not have been terminated
                  pursuant to subsections 9(A) or 9(B) above, then

                                       21
<PAGE>

                  notwithstanding anything in this Section 9 to the contrary,
                  Lessee shall have the right to terminate this Lease if the
                  restoration work to be performed by Lessor with respect to the
                  Building shall not have been substantially completed within
                  one hundred eighty (180) days of the date of the occurrence of
                  the damage for any reason, subject to delay caused by Lessee
                  or Lessee's employees, agents, or contractors or Force
                  Majeure, but in no event later than two hundred forth (240)
                  days in the aggregate after the date of occurrence of the
                  damage. Lessee shall exercise its right to terminate this
                  Lease by giving written notice of termination to Lessor on or
                  before the date that is thirty (30) days after the expiration
                  of the aforesaid one hundred eighty (180) period, as extended
                  by Force Majeure as aforesaid. In the event Lessee exercises
                  its right to terminate this Lease, this Lease shall terminate
                  on the thirtieth (30th) day following Lessor's receipt of
                  Lessee's written notice of termination, unless the restoration
                  work to be performed by Lessor with respect to the Building
                  shall have been substantially completed within said thirty
                  (30) day period. In the event Lessor determines, as the
                  restoration work progresses, that it will not be able to
                  substantially complete the restoration work to be performed by
                  Lessor with respect to the Building within one hundred eighty
                  (180) days of the date of the vesting of title (whether for
                  Force Majeure or otherwise), Lessor shall promptly notify
                  Lessee in writing ("Delay Notice") of the Lessor's reasonable
                  estimate of time period required to substantially complete
                  such restoration work. Lessee shall be deemed to have
                  consented to a delay in the date for substantial completion of
                  the restoration work unless Lessee shall notify Lessor in
                  writing within ten (10) days of its receipt of the Delay
                  Notice that Lessee desires to terminate this Lease in which
                  event the Lease shall terminate thirty (30) days following
                  Lessor's receipt of the written termination notice, provided,
                  however, that Lessee shall not be permitted to terminate this
                  Lease pursuant to this sentence, if substantial completion of
                  Lessor's restoration work can reasonably be achieved within
                  two hundred forty (240) days of the date of the occurrence of
                  the damage. Term Basic Rent and Additional Rent shall be
                  apportioned as of the date of the occurrence of the damage if
                  the entire Premises shall have been rendered untenantable or
                  on the effective termination date if only part of the Premises
                  shall have been rendered untenantable.

            (D)   In any case in which use of the Premises (or access thereto)
                  is materially affected by any damage to the Building, there
                  shall be either an abatement or an equitable reduction in
                  Annual Basic Rent for the period for which and the extent to
                  which the Premises are not reasonably usable and enjoyable for
                  the purpose for which they are leased hereunder. The words
                  "restoration" and "restore" as used in this Section 9 shall
                  include repairs.

                                       22
<PAGE>

                  If the damage results from the fault of Lessee, or Lessee's
                  agents, servants, visitors or licensees, Lessee shall not be
                  entitled to any abatement or reduction in Term Basic Rent,
                  except to the extent of any rent insurance received by Lessor.

10. EMINENT DOMAIN.

            (A)   If Lessee's use of the Premises or if Lessee's access to the
                  Premises or the parking area serving the Building are
                  materially affected such that Lessee cannot use the Premises
                  for its intended use during the remainder of the Term, due to
                  the taking by eminent domain of (i) the Premises or any part
                  thereof or any estate therein; or (ii) any other part of the
                  Building; then, in either event, this Lease shall terminate on
                  the date when title vests pursuant to such taking. The Term
                  Basic Rent, and any Additional Rent, shall be apportioned as
                  of said termination date and any Term Basic Rent or Additional
                  Rent paid for any period beyond said date shall be reimbursed
                  to Lessee. Under such circumstance, Lessee shall not be
                  entitled to any part of the award for such taking or any
                  payment in lieu thereof, but Lessee may file a separate claim
                  for any taking of the Lessee Improvement Work (less an amount
                  equal to the unamortized portion of the Lessee Allowance paid
                  to Lessee, computed on the straight-line basis over the
                  initial Term of this Lease), for loss of business and for
                  moving expenses, provided the same shall in no way affect or
                  diminish Lessor's award.

            (B)   In the event of a partial taking which does not effect a
                  termination of this Lease but does deprive Lessee of the use
                  of a portion of the Demised Premises, there shall either be an
                  abatement or an equitable reduction of the Term Basic Rent,
                  and an equitable adjustment reducing the Base Period Costs as
                  hereinafter defined depending on the period for which and the
                  extent to which the Premises so taken are not reasonably
                  usable for the purpose for which they are leased hereunder.
                  Lessee shall not be entitled to any part of the award for such
                  taking or any payment in lieu thereof, but Lessee may file a
                  separate claim for loss of business, provided the same shall
                  in no way affect or diminish Lessor's award. Under such
                  circumstances, Lessor shall include as part of its claim for
                  such eminent domain taking, an amount equal to the replacement
                  value of the Lessee Improvement Work affected by such taking.
                  Any net proceeds received by Lessor relating to the taking of
                  the Lessee Improvement Work shall be allocated as follows: (x)
                  first, to the Lessor an amount equal to the lesser of the
                  Lessee Allowance paid to Lessee, or an amount equal to the net
                  proceeds received by Lessor for the Lessee Improvement Work
                  affected by such taking, times a fraction where (a) the
                  numerator is the Lessee

                                       23
<PAGE>

                  Allowance, and (b) the denominator is the total cost of the
                  Lessee Improvement Work, which shall be retained by Lessor
                  (subject to the provisions of the following sentence), and (y)
                  the balance, if any, to Lessee to be used for Lessee's
                  restoration obligations hereunder. To the extent that any
                  condemnation proceeds are retained by Lessor, such proceeds
                  shall be held by Lessor in trust, in an interest-bearing
                  account and provided no Event of Default has occurred and is
                  continuing, disbursed to Lessee subject to the same conditions
                  for disbursement of the Lessee Allowance as set forth in
                  Section 26(C) of this Lease, following final completion of the
                  restoration work required to be done by Lessee pursuant to
                  subsections 10(C) through 10(E) below.

            (C)   If this Lease is not terminated as provided in Section 10(A)
                  above, Lessor shall (except as set forth in the following
                  sentence) restore the Building and the Premises with
                  reasonable promptness following the date when title vests
                  pursuant to such taking, subject to Force Majeure, as
                  hereinafter defined and Lessee shall have no right to
                  terminate this Lease, except as specifically set forth in
                  subsection 10(D) below. Notwithstanding the foregoing, if
                  Lessor is required to restore the portion of the Building and
                  Premises affected by such taking, pursuant to the provisions
                  of this Section 10, Lessee shall, subject to Force Majeure,
                  promptly commence and prosecute restoration of all affected
                  Lessee Improvement Work, and such other fixtures, improvements
                  or systems owned and/or installed by Lessee, following
                  substantial completion of Lessor's restoration work (or at
                  such earlier time as Lessee and Lessor mutually agree). In
                  addition to all other applicable provisions of this Lease,
                  Lessee's restoration work shall be performed and completed in
                  accordance with the provisions of Sections 6 and 26 hereof.

            (D)   Anything contained in this Section 10 to the contrary
                  notwithstanding, within sixty (60) days after the date when
                  title vests pursuant to such taking described in Section 10(B)
                  above, Lessor shall deliver to Lessee a statement prepared by
                  a reputable contractor selected by Lessor and reasonably
                  acceptable to Lessee, setting forth such contractor's estimate
                  as to the time required for Lessor to restore the portion of
                  the Building for which Lessor is responsible. If the estimated
                  time period exceeds one hundred eighty (180) days from the
                  date when title vests pursuant to such taking, Lessee may
                  elect to terminate this Lease by notice to Lessor not later
                  than thirty (30) days following receipt of such statement. If
                  Lessee shall not elect to terminate this Lease as aforesaid
                  (or is not entitled to terminate this Lease pursuant to this
                  Section,) then Lessor and Lessee shall restore the Building
                  and the Premises as required herein with reasonable
                  promptness.

                                       24
<PAGE>

            (E)   Notwithstanding anything in this Sectino10 to the contrary,
                  Lessee shall have the right to terminate this Lease if the
                  restoration work to be performed by Lessor with respect to the
                  Building shall not have been substantially completed, for any
                  reason, within one hundred eighty (180) days from the date
                  when title vests pursuant to such taking, subject to delay
                  caused by Lessee or Lessee's employees, agents, or contractors
                  or Force Majeure, but in no event later than two hundred forty
                  (240) days in the aggregate after the date when title vests
                  pursuant to such taking. Lessee shall exercise its right to
                  terminate this Lease by giving written notice of termination
                  to Lessor on or before the date that is thirty (30) days after
                  the expiration of the aforesaid one hundred eighty (180)
                  period, as extended by Force Majeure as aforesaid. In the
                  event Lessee exercises its right to terminate this Lease, this
                  Lease shall terminate on the thirtieth (30th) day following
                  Lessor's receipt of Lessee's written notice of termination,
                  unless the restoration work to be performed by Lessor with
                  respect to the Building shall have been substantially
                  completed within said thirty (30) day period. In the event
                  Lessor determines, as the restoration work progresses, that it
                  will not be able to substantially complete the restoration
                  work to be performed by Lessor with respect to the Building
                  within one hundred eighty (180) days of the date of the
                  vesting of title (whether for Force Majeure or otherwise),
                  Lessor shall promptly notify Lessee in writing ("Delay
                  Notice") of the Lessor's reasonable estimate of time period
                  required to substantially complete such restoration work.
                  Lessee shall be deemed to have consented to a delay in the
                  date for substantial completion of the restoration work unless
                  Lessee shall notify Lessor in writing within ten (10) days of
                  its receipt of the Delay Notice that Lessee desires to
                  terminate this Lease in which event the Lease shall terminate
                  thirty (30) days following Lessor's receipt of the written
                  termination notice, provided, however, that Lessee shall not
                  be permitted to terminate this Lease pursuant to this
                  sentence, if substantial completion of Lessor's restoration
                  work can reasonably be achieved within two hundred forty (240)
                  days of the date of the vesting of title.

11. INSOLVENCY OF LESSEE, OTHER DEFAULTS. If an Event of Bankruptcy (as
hereinafter defined) shall occur, Lessor may terminate this Lease forthwith and
upon notice of such termination Lessee's right to possession of the Demised
Premises shall cease, and Lessee shall then quit and surrender the Premises to
Lessor but Lessee shall remain liable as provided in Section 13 hereof.

            The following shall be "Events of Bankruptcy" under this Lease:

                                       25
<PAGE>

            (A)   Lessee's becoming insolvent, as that term is defined in Title
                  11 of the United States Code, entitled Bankruptcy, 11 U.S. C.
                  ss.101 et seq. (as may be amended, supplemented or replaced
                  from time to time, the "Bankruptcy Code"), or under the
                  insolvency laws of any State, District, Commonwealth or
                  Territory of the United States as applicable to Lessee (the
                  "Insolvency Laws");

            (B)   the appointment of a receiver or custodian for all or a
                  substantial portion of Lessee's property or assets, or the
                  institution of a foreclosure action upon all or a substantial
                  portion of Lessee's real or personal property which shall not
                  have been vacated, discharged or stayed or bonded pending
                  appeal within sixty (60) days from entry thereof;

            (C)   the filing of a voluntary petition by Lessee under the
                  provision of the Bankruptcy Code or Insolvency Laws;

            (D)   the filing of an involuntary petition against Lessee as the
                  subject debtor under the Bankruptcy Code or Insolvency Laws,
                  which is either dismissed within sixty (60) days of filing, or
                  results in the issuance of an order for relief against the
                  debtor, whichever is later; or

            (E)   Lessee's making or consenting to an assignment for the benefit
                  of creditors or a common law composition of creditors.

12. LESSOR'S REMEDIES ON DEFAULT. If Lessee defaults in the payment of Term
Basic Rent, or any Additional Rent, or defaults pursuant to Subsection 29(A)(v)
hereof or permits the Premises to become deserted, abandoned or vacated or
defaults in the performance of any of the other covenants and conditions hereof,
Lessor shall (except for a Term Basic Rent default, where at least two (2) other
Term Basic Rent defaults have occurred during the then preceding twelve (12)
month period of which Lessor has given Lessee notice) give Lessee notice of such
default, and if Lessee does not (i) pay the amount of Term Basic Rent within ten
(10) days of the giving of the aforementioned required notice, or if no notice
is required within ten (10) days from the date such payment was due, or (ii)
cure any Additional Rent default within ten (10) days of the giving of such
notice, or (iii) cure the default pursuant to Subsection 29(A)(v) within
forty-eight (48) hours of the giving of such notice, or (iv) cure any other
default within thirty (30) days after giving of such notice (provided that if
such other default is of such nature that it cannot be completely cured within
such period, if Lessee does not commence such curing within such thirty (30)
days and thereafter proceed with reasonable diligence and in good faith to cure
such default and such default is not thereafter cured within the lesser of (a)
one hundred twenty (120) days from the giving of such notice or (b) such period
of time from the giving of such Notice which equals the amount of time which
Lessor has to cure a similar non-monetary default as described in any underlying
mortgage, lease or trust deed, as same may be extended by said mortgagee, lessee
or trustee from time to time; it being agreed that Lessor shall provide

                                       26
<PAGE>

Lessee with a copy of such mortgage, lease or trust deed or notice of the
relevant provisions) (each of the foregoing being an "Event of Default"), then
Lessor may terminate this Lease on not less than ten (10) days notice to Lessee,
and on the date specified in said notice, Lessee's right to possession of the
Demised Premises shall cease, and Lessee shall then quit and surrender the
Premises to Lessor, but Lessee shall remain liable as hereinafter provided. If
this Lease shall have been so terminated by Lessor pursuant to Sections 11 or 12
hereof, Lessor may at any time thereafter resume possession of the Premises by
any lawful means and remove Lessee or other occupants and their effects.

13. DEFICIENCY.

            (A)   In any case where Lessor has recovered possession of the
                  Premises by reason of Lessee's default, Lessor may, at
                  Lessor's option, occupy the Premises or cause the Premises to
                  be redecorated, altered, divided, consolidated with other
                  adjoining premises, or otherwise changed or prepared for
                  reletting, and may relet the Premises or any part thereof as
                  agent of Lessee or otherwise, for a term or terms to expire
                  prior to, at the same time as, or subsequent to, the original
                  expiration date of this Lease, at Lessor's option, and receive
                  the Term Basic Rent or Additional Rent therefor. Term Basic
                  Rent and Additional Rent so received shall be applied first to
                  the payment of such expenses as Lessor may have incurred in
                  connection with the recovery of possession, redecorating,
                  altering, dividing, consolidating with other adjoining
                  premises, or otherwise changing or preparing for reletting,
                  and the reletting, including brokerage and reasonable
                  attorney's fees, and then to the payment of damages in amounts
                  equal to the Term Basic Rent and Additional Rent hereunder and
                  to the costs and expenses of performance of the other
                  covenants of Lessee as herein provided. Lessee agrees, in any
                  such case, whether or not Lessor has relet, to pay to Lessor
                  damages equal to the Term Basic Rent and Additional Rent and
                  other sums herein agreed to be paid by Lessee, as and when
                  due, less the net proceeds of the reletting, if any, as
                  ascertained from time to time, as of the due date, and the
                  same shall be payable by Lessee on the several rents days
                  above specified, Lessee shall not be entitled to any surplus
                  accruing as a result of any such reletting nor shall any
                  surplus be applied to offset any damages referred to in the
                  preceding sentence. In reletting the Premises as aforesaid,
                  Lessor may grant rent concessions, and Lessee shall not be
                  credited therewith. No such reletting shall constitute a
                  surrender and acceptance or be deemed evidence thereof.

            (B)   Alternatively, in any case where Lessor has recovered
                  possession of the Premises by reason of Lessee's default,
                  Lessor may at Lessor's option, and at any time thereafter, and
                  without notice or other action by Lessor, and without
                  prejudice to any other rights or remedies it might have
                  hereunder

                                       27
<PAGE>

                  or at law or equity, become entitled to recover from Lessee,
                  as damages for such breach, in addition to such other sums
                  herein agreed to be paid by Lessee, an amount equal to the
                  difference between (i) the Term Basic Rent and Additional Rent
                  reserved in this Lease from the date of such default to the
                  date of expiration of the Term demised (assuming the Lease had
                  not been terminated by reason of such default), as the same
                  may have been extended or renewed, and (ii) the then fair and
                  reasonable rental value of the Premises for the same period
                  (net of a six month reletting period); both discounted to
                  present worth at the then current Applicable Treasury Rate.
                  The "Applicable Treasury Rate" shall equal the then current
                  yield on U.S. Treasury obligations having a maturity which is
                  closest to the date of expiration of the Term demised
                  (assuming the Lease had not been terminated by reason of such
                  default), as the same may have been extended or renewed. Said
                  damages shall become due and payable to Lessor immediately
                  upon such breach of this Lease and without regard to whether
                  this Lease be terminated or not, and if this Lease be
                  terminated, without regard to the manner in which it is
                  terminated.

            (C)   Lessee hereby waives all right of redemption to which Lessee
                  or any person under Lessee might be entitled by any law now or
                  hereafter in force. In addition, if an Event of Default occurs
                  which results in the Lessor recovering possession of the
                  Demised Premises, Lessor shall be under no duty to mitigate
                  Lessee's damages as provided for in this Section 13. Lessor's
                  remedies hereunder are in addition to any remedy allowed by
                  law or in equity.

14. SUBORDINATION OF LEASE. Subject to the provisions contained in any
subordination, non-disturbance and attornment agreement executed by and among
Lessor, Lessee and the holder of any underlying lease, mortgage or trust deed,
this Lease and any option contained herein shall, at Lessor's option, or at the
option of any holder of any underlying lease or holder of any mortgage or trust
deed, be subject and subordinate to any such underlying leases and to any such
mortgage or trust deed which may now or hereafter affect the real property of
which the Premises form a part, and also to all renewals, modifications,
consolidations and replacements of said underlying leases and said mortgages or
trust deed. Although no instrument or act on the part of Lessee shall be
necessary to effectuate such subordination, Lessee will, nevertheless, execute
and deliver such further instruments confirming such subordination of this Lease
as may be desired by the holders of any said mortgage or trust deed or by any of
the Lessors under such underlying leases. If any mortgage or deed of trust is
foreclosed or if a deed in lieu of foreclosure covering the Office Building Area
is given to the holder of a mortgage or deed of trust (or its designee), Lessee
shall, on request, attorn to the holder of such mortgage, or deed of trust (or
its designee). If any underlying lease to which this Lease is subject shall be
terminated, Lessee shall, on request, attorn to the owner of the reversion.
Notwithstanding anything to the contrary contained herein, the foregoing
subordination of this Lease shall be

                                       28
<PAGE>

conditioned on the holder of any underlying lease or holder of any mortgage or
trust deed entering into a subordination, non-disturbance and attornment
agreement ("SNDA") with Lessee substantially in the form attached hereto as
Exhibit G. With respect to any mortgage encumbering the Office Building Area on
the date hereof, Lessor shall deliver the SNDA on the date hereof. Lessor
represents that there are no ground or similar underlying leases currently
affecting the real property of which the Premises are a part.

15. SECURITY DEPOSIT/LETTER OF CREDIT. On or prior to the date hereof, Lessee
shall have deposited with Lessor an irrevocable standby letter of credit issued
by BankBoston, N.A., in the face amount of One Hundred Fifty Thousand Dollars
($150,000) and in form satisfactory to Lessor (the "Letter of Credit"). The
Letter of Credit shall have an initial term of five (5) years and thereafter,
during the Term, shall be renewed by Lessee not later than thirty (30) days
prior to the expiration of such Letter of Credit (as extended from time to
time). Each renewal Letter of Credit shall be issued by a bank or other
financial institution reasonably acceptable to Lessor (if the credit rating of
such entity is at least equal to that of the initial issuer as of the date
hereof then such entity shall be deemed acceptable to Lessor) and shall be in
the same amount and on the same terms and conditions as the initial Letter of
Credit. The obligation to renew the Letter of Credit shall continue throughout
the Term and the Letter of Credit shall not be permitted to expire or terminate
until at least ninety-one (91) days after the last day of the Term. If any Event
of Default has occurred, Lessor may at any time from time to time and without
prejudice to any other remedy, draw down all or any portion of the Letter of
Credit to the extent necessary to make good any arrears of any amount due but
not paid under this Lease, or any other damage, injury, expense or liability
caused to Lessor by such Event of Default. The Letter of Credit shall not be
considered an advance payment of rent or a measure of Lessor's damages in case
of default by Lessee. In the event of the sale or transfer of Lessor's interest
in the Demised Premises, Lessor shall have the right to transfer all or any
portion of Letter of Credit to the purchaser or transferee (and Lessee will take
such actions as are necessary to cause the Letter of Credit to be issued in the
name of such transferee), and upon such transfer Lessee shall thereafter look
only to the new lessor for the return of the Letter of Credit, and Lessor shall
thereupon be released from all liability to Lessee for the return of or account
for such Letter of Credit. If all or any portion of the Letter of Credit is
used, applied or retained by Lessor, Lessee shall, within ten (10) days after a
draw on the Letter of Credit, cause the amount available under the Letter of
Credit to be increased to One Hundred Fifty Thousand Dollars ($150,000). Draws
on the Letter of Credit shall require only delivery of a certification by Lessor
that there has occurred an Event of Default under the Lease and the issuer shall
be entitled to rely thereon without need to verify the factual accuracy thereof.

16. RIGHT TO CURE BREACH. If Lessee breaches any covenant or condition of this
Lease and if the giving of notice by Lessor is required pursuant to this Lease,
then if such breach is not cured within any applicable notice and cure period
contained in this Lease, Lessor may, on not less than (10) days prior written
notice to Lessee (except that no notice need be given in case of emergency),
cure such breach at the expense of Lessee and the reasonable amount of all
expenses, including reasonable attorneys' fees, with interest thereon at the
Interest Rate (as

                                       29
<PAGE>

hereinafter defined) incurred by Lessor in so doing shall be deemed Additional
Rent payable on demand.

17. LIENS.

            (A)   Lessee shall not allow any lien or other encumbrance to be
                  filed upon any interest of Lessor or any ground or underlying
                  lessor in any portion of the Premises, the Building and/or
                  Office Building Area. If, because of any act or omission (or
                  alleged act or omission) of Lessee, any construction lien
                  claim or other lien (collectively "Lien"), charge, or order
                  for the payment of money or other encumbrance shall be filed
                  against Lessor and/or any ground or underlying lessor and/or
                  any portion of the Premises, the Building or Office Building
                  Area (whether or not such Lien, charge, order, or encumbrance
                  is valid or enforceable as such), Lessee shall, at its own
                  cost and expense, cause same to be discharged of record or
                  bonded within thirty (30) days after the filing thereof; and
                  Lessee shall indemnify and save harmless Lessor and all ground
                  and underlying lessor(s) against and from all costs,
                  liabilities, suits, penalties, claims, and demands, including
                  reasonable counsel fees, resulting therefrom. If Lessee fails
                  to comply with the foregoing provisions, Lessor shall have the
                  option of discharging or bonding any such Lien, charge, order,
                  or encumbrance, and Lessee agrees to reimburse Lessor for all
                  reasonable costs, expenses and other sums of money in
                  connection therewith (as Additional Rent) with interest at the
                  Interest Rate upon demand. All materialmen, contractors,
                  artisans, mechanics, laborers, and any other persons now or
                  hereafter contracting with Lessee of any contractor or
                  subcontractor of Lessee for the furnishing of any labor
                  services, materials, supplies, or equipment with respect to
                  any portion of the Premises, at any time from the date hereof
                  until the end of the Lease Term, are, to the extent allowed by
                  applicable law, hereby charged with notice that they are to
                  look exclusively to Lessee to obtain payment for same.

            (B)   "Interest Rate" shall mean a rate per annum equal to the prime
                  or base commercial lending rate from time to time announced by
                  Citibank N.A. (or its successors) to be in effect at its
                  principal office in New York, New York plus three (3%) percent
                  bu in no event in excess of the maximum rate of interest
                  permitted under applicable law.

18. RIGHT TO INSPECT AND REPAIR. Lessor may enter the Premises but shall not be
obligated to do so (except as required by any specific provision of this Lease)
at any reasonable time on prior reasonable notice (which need not to be in
writing, but Lessor shall make reasonable efforts to deliver same to Lessee) to
Lessee (except that no notice need be given in case of emergency) for the
purpose of inspection or the making of such repairs, replacement or

                                       30
<PAGE>

additions, in, to, on and about the Premises as Lessor is required or permitted
to make hereunder or otherwise at the Building, as Lessor deems reasonably
necessary or desirable. Lessee shall be entitled to have a representative
accompany Lessor at the appointed time of entry; provided that such does not
unreasonably interfere with or prevent Lessor from taking the aforementioned
actions. Lessee shall have no claims or cause of action against Lessor by reason
thereof, but Lessor shall use reasonable efforts to minimize any such
disturbance consistent with practices in office buildings similar to the
Building in the Piscataway area.

19. SERVICES TO BE PROVIDED BY LESSOR.

            (A)   Subject to intervening laws, ordinances, regulations and
                  executive orders, if any, Lessor agrees to furnish during
                  Building Hours (as defined in Section 40D), except on holidays
                  as set forth on Exhibit D attached hereto and made a part
                  hereof, and at such other hours as provided herein, subject to
                  reimbursement as provided for in Section 21 and 22, the
                  following:

                  (i)   The cleaning services, as set forth on Exhibit C
                        attached hereto and made a part hereof, and subject to
                        the conditions therein stated. Except as set forth on
                        Exhibit C, Lessee shall pay the cost of all other
                        cleaning services required by Lessee.

                  (ii)  Heating, ventilating and air conditioning (herein
                        "HVAC") to the Premises; provided, however, that if
                        Lessee elects to install a Split System to service only
                        the Premises, then Lessor shall no longer be responsible
                        for furnishing HVAC to the Premises and the Annual Basic
                        Rent shall be reduced by $1 per gross rentable square
                        foot of space contained in the Premises. Lessor hereby
                        consents, subject to the other provisions of Section 6
                        and the applicable provisions of Section 5 of this
                        Lease, to the installation by Lessee of a Split System
                        for supplying HVAC to the Premises, and if Lessee makes
                        the foregoing election, then all of the foregoing shall
                        be included in the definition of Lessee Improvement
                        Work. Lessor shall, subject to the provisions of Section
                        6 and the applicable provisions of Section 5 of this
                        Lease, permit Lessee at Lessee's sole cost and expense,
                        to tie into the existing hot and cold water supply and
                        condenser water supply, the existing base Building
                        ventilation ductwork and other systems of the Building
                        as is reasonably necessary to adequately service the
                        Split System. Lessor shall furnish HVAC to the Common
                        Facilities together with Common Facilities lighting and
                        electric energy. Lessor shall provide electric energy
                        for overhead lighting and outlet usage in the Premises
                        during Building Hours and non-Building Hours (the
                        consumption costs of which shall be borne by Lessee),
                        which shall not exceed

                                       31
<PAGE>

                        four (4) watts per square foot of the Premises per
                        working hour (it being agreed that Lessee may, as part
                        of its Lessee Improvement Work and if permitted by the
                        company providing electrical service to the Demised
                        Premises, upgrade the electrical capacity to
                        approximately 800 amps at 480/277 volts); provided,
                        however, that in the event that Lessee elects to have
                        the electric or any other utility serving the Premises
                        directly metered by the utility company providing such
                        service (rather than sub-metered by Lessor), then, upon
                        Lessor obtaining such direct service, the Lessor shall
                        not be responsible for providing any such electric or
                        utility service to the Premises and the work related to
                        such election shall be included in the definition of
                        Lessee Improvement Work.

                  (iii) During Building Hours and non-Building Hours, cold and
                        hot water for drinking and lavatory purposes and gas
                        service; subject to the provisions set forth in subject
                        A (ii) above regarding Lessee's election to have such
                        services directly metered.

                  (iv)  Snow plowing and lawn care (including, without
                        limitation, the planting of seasonal plants in the
                        courtyard portion of the Office Building Area)
                        consistent with other buildings of similar class as that
                        of the Building in the area of the Building.

                  (v)   No later than December 31, 1998, Lessor shall repave the
                        courtyard portion of the Office Building Area and
                        replant the area with seasonal plants.

            (B)   Lessee shall have access to the Building, parking area and the
                  Premises twenty-four (24) hours per day, seven (7) days per
                  week, subject to reasonable security provisions that may be
                  established from time to time by Lessor with respect to such
                  access during non Building Hours.

20. INTERRUPTION OF SERVICES OR USE. Interruption or curtailment of any service
maintained in the Building or at the Office Building Area, if caused by Force
Majeure, as hereinafter defined, shall not, except as otherwise provided herein,
entitle Lessee to any claim against Lessor or to any abatement of Term Basic
Rent or Additional Rent, and shall not constitute a constructive or partial
eviction. If the Premises are rendered untenantable in whole or in part, for a
period of ten (10) consecutive business days, by any interruption or curtailment
of any service maintained by Lessor, or for any other reason, including, without
limitation, Force Majeure, (other than any interruption of electric or any other
utility service not provided by Lessor pursuant to Section 19 above and/or by
any other interruption caused by misuse or neglect by Lessee, or Lessee's
agents, servants, visitors or licensees), there shall be a proportionate
abatement of Monthly Basic Rent from and after said tenth (10th) consecutive
business day and

                                       32
<PAGE>

continuing for the period of such untenantability. The remedies provided for in
this Section 20 shall be Lessee's sole remedies for any interruption of service
or use as described above.

21. ELECTRICAL AND OTHER UTILITY SERVICES.

            (A)   Lessee, as part of the Lessee Improvement Work, shall install
                  all such sub-meters required to measure all electrical and
                  other utility consumption required for Lessee's use and
                  occupation of the Premises. Lessee shall be responsible for
                  the payment to Lessor, as Additional Rent, the amount charged
                  by the utility company furnishing such electrical power and
                  other utility service, as registered on each such sub-meter.
                  Lessor shall cause each such sub-meter to be read monthly and
                  shall invoice Lessee on a monthly basis for Lessee's
                  electrical and other utility consumption. Such amounts shall
                  be paid by Lessee within ten (10) days after being invoiced by
                  Lessor. Notwithstanding anything to the contrary contained in
                  this subsection 21(A), Lessee may elect, at Lessee's sole cost
                  and expense (subject to the provisions of Section 6 of this
                  Lease and otherwise subject to Lessor's reasonable approval),
                  to install a meter (or meters) to measure Lessee's electrical
                  and/or other utility consumption within the Premises. In the
                  event of such election, Lessee shall timely pay directly to
                  the applicable utility company furnishing services to the
                  Premises, all amounts charged for electric and utility
                  consumption. If Lessee shall obtain electricity or any other
                  utility directly from the applicable utility company, Lessee
                  shall have the right to use all existing risers, wires,
                  conduits and electrical and other applicable utility equipment
                  servicing the Premises in a manner consistent with its
                  intended use, subject to the other provisions of this Lease.

            (B)   Lessor shall not be liable in any way to Lessee for any
                  change, failure, inadequacy or defect in the supply or
                  character of electrical energy and/or other utility service
                  furnished to the Demised Premises, unless caused by the gross
                  negligence or willful misconduct of Lessor, Lessor's
                  employees, agents or contractors. Notwithstanding anything to
                  the contrary contained in this Lease, Lessee shall be
                  responsible for any repair, maintenance and replacement of any
                  electrical and/or other utility meter (or sub-meter), panel
                  board, wires, wiring, feeders, risers, pipes, plumbing, and
                  such other related fixtures and equipment installed by Lessee
                  and used in connection with the electrical and/or other
                  utilities furnished to the Demised Premises, at Lessee's
                  expenses, or if Lessor causes such work to be performed,
                  Lessee shall pay Lessor the reasonable charges therefor within
                  thirty (30) days of demand.

                                       33
<PAGE>

            (C)   Lessee agrees not to connect any additional electrical
                  equipment of any type to the Buildings' electrical
                  distribution system, other than lamps, typewriters and other
                  similar customary office machines which consume comparable
                  amounts of electricity (including without limitation personal
                  computers and copy machines) and scientific electrical
                  equipment common to a research laboratory facility, without
                  the Lessor's prior written consent. In no event shall Lessee
                  use or install any fixtures, equipment or machines the use of
                  which in conjunction with other fixtures, equipment and
                  machines in the Demised Premises would result in an overload
                  of the electrical circuits servicing the Demised Premises. In
                  order to insure that such electrical capacity is not exceeded
                  and to avert any possible adverse effect upon the Building's
                  electrical system, Lessee shall not, except as otherwise
                  provided herein, without the prior consent of Lessor (which
                  consent shall not be unreasonably withheld or delayed,
                  provided that the withholding of consent shall be deemed
                  reasonable if it is based upon an unreasonably
                  disproportionate demand of electricity for the Demised
                  Premises as the Demised Premises relates to the Building as a
                  whole), make or perform or permit any alteration to wiring
                  installations or electrical facilities in or serving the
                  Demised Premises or any additions to the electrical fixtures,
                  business machines, or office equipment or appliances (other
                  than typewriters, desk top personal computers and similar low
                  energy consuming office machines and scientific electrical
                  equipment common to research laboratory facilities) in the
                  Demised Premises which utilize electrical energy. Lessor, at
                  its option, before the commencement of any work to be paid for
                  by Lessee hereunder or at any time thereafter, may require
                  Lessee to furnish to Lessor such security, whether by surety
                  bond, issued by a corporation satisfactory to Lessor, in form
                  and amount and licensed to do business in the State of New
                  Jersey, or otherwise, as Lessor shall deem reasonably
                  necessary to assure the payment for such work by Lessee.

            (D)   Lessee shall, at its expense, furnish and install all
                  replacement lighting tubes, lamps, ballasts and bulbs required
                  in the Premises.

22. ADDITIONAL RENT. It expressly agreed that Lessee will pay in addition to the
Term Basic Rent provided in Section 3 above, as additional rental to cover
Lessee's Percentage of the increased cost to Lessor, for each of the categories
enumerated herein, over the Base Period Costs for each such category.

            (A)   Operating Cost Escalation.

                  (i)   If during the Lease Term the Operating Costs incurred
                        for the Building in which the Demised Premises are
                        located and Office

                                       34
<PAGE>

                        Building Area for any calendar year or proportionate
                        part thereof if the Lease Term expires prior to the
                        expiration of a calendar year (herein the "Comparison
                        Period") shall be greater than the Base Operating Costs
                        (adjusted proportionately if the Comparison Period is
                        less than a calendar year), then Lessee shall pay to
                        Lessor, as Additional Rent, Lessee's Percentage of all
                        such excess Operating Costs. Operating Costs shall
                        include all reasonable costs and expenses of owning,
                        operating, managing, maintaining, repairing, replacing
                        and securing the Building and the Office Building Area
                        including, by way of illustration and not by way of
                        limitation: personal property taxes; asset and/or
                        property management fees; labor, including all wages and
                        salaries and benefits for those individuals rendering
                        services to the Building and/or the Office Building
                        Area, which are generally comparable to the wages,
                        salaries and benefits paid to those providing services
                        to other buildings of comparable quality in the general
                        area of the Building but not including any employees
                        above the rank of building or property manager; social
                        security taxes, and other taxes (excluding late payment
                        charges) which may be levied against Lessor upon such
                        wages and salaries; supplies; repairs, maintenance and
                        replacements; maintenance and service contracts;
                        painting; wall and window washing; tools and equipment
                        (which are not required to be capitalized under
                        generally accepted accounting principles); fire, rent,
                        liability and other insurance; trash removal; lawn care;
                        snow removal; sums levied, assessed, imposed or required
                        to be paid to any governmental authority on account of
                        the parking of motor vehicles, including all sums
                        required to be paid pursuant to transportation controls
                        imposed by the Environmental Protection Agency under the
                        Clean Air Act of 1970, or otherwise required to be paid
                        by any governmental authority with respect to the
                        parking, use, or transportation of motor vehicles, or
                        reduction or control of motor vehicle traffic, or motor
                        vehicle pollution; and all other items properly
                        constituting direct operating costs according to
                        standard accounting practices (hereinafter collectively
                        referred to as the "Operating Costs") but not including
                        Real Estate Taxes (as hereinafter defined), Utility and
                        Energy Costs, depreciation of Building or equipment;
                        principal or interest; income or excess profits taxes;
                        costs of maintaining Lessor's corporate existence;
                        franchise taxes; any expenditures required to be
                        capitalized (an "Included Capital Improvement") under
                        generally accepted accounting principles, unless said
                        expenditures are for the purpose of reducing Operating
                        Costs within the Building and Office Building Area (and
                        in such instance

                                       35
<PAGE>

                        only to the extent of savings generated in connection
                        therewith or the amortized amount as provided herein, if
                        less) or are required under any mandatory governmental
                        law, ordinance or regulation, in which event the costs
                        thereof shall be included, but only to the extent of the
                        amortization of such Included Capital Improvement over
                        the useful life thereof; leasing commissions; tenant
                        work allowances (or work done for tenants); brokerage
                        commissions,; origination fees, points, mortgage
                        recording taxes, title charges and other costs or fees
                        incurred in connection with financing or refinancing or
                        sale or transfer of the Building or any portion thereof
                        or any interest therein; attorneys fees in connection
                        with leasing of space (or surrender, modification,
                        termination, extension or enforcement of any lease); any
                        expense paid to any related entity to the extent such
                        payment exceeds competitive charges in a bona fide
                        arms-length transaction; marketing, promotion and
                        advertising expenses; ground rent. As used in this
                        Subsection 22(A), the Base Period Costs for Operating
                        Costs shall be as defined in the Preamble.

            (B)   Fuel, Utilities and Electric Cost Escalation (hereinafter
                  "Utility and Energy Costs"). If during the Lease Term the
                  Utility and Energy Costs, including any fuel surcharges or
                  adjustments with respect thereto, incurred for water, sewer,
                  gas, electric, other utilities and heating, ventilating and
                  air conditioning for the Building to include all leased and
                  leasable areas (not separately billed or metered within the
                  Building) and Common Facilities electric lighting, water,
                  sewer and other utilities for the Building and Office Building
                  Area, for any Comparison Period shall be greater than the Base
                  Utility and Energy Costs (adjusted proportionately if the
                  Comparison Period is less than a calendar year), then Lessee
                  shall pay to Lessor, as Additional Rent, Lessee's Percentage
                  of all such excess Utility and Energy Costs. As used in this
                  Subsection 22(B), the Base Period Costs for Utility and Energy
                  Costs shall be as defined in the Preamble.

            (C)   Tax Escalation.

                  (i)   If during the Lease Term the Real Estate Taxes for the
                        Building and Office Building Area at which the Demised
                        Premises are located for any Comparison Period shall be
                        greater than the Base Real Estate Taxes (adjusted
                        proportionately if the Comparison Period is less than a
                        calendar year), then Lessee shall pay to Lessor as
                        Additional Rent, Lessee's Percentage, as hereinafter
                        defined, of all such excess Real Estate Taxes.

                                       36
<PAGE>

                  (ii)  As used in this Subsection 22(C), the words and terms
                        which follow mean and include the following:

                        (a)   The Base Period Costs for "Real Estate Taxes"
                              shall be as defined in the Preamble.

                        (b)   "Real Estate Taxes" shall mean the property taxes
                              and assessments imposed upon the Building and
                              Office Building Area including, but not limited
                              to, real estate, city, county, village, school and
                              transit taxes, or taxes, assessments or charges
                              levied, imposed, or assessed against the Building
                              and Office Building Area by any other taxing
                              authority, whether general or specific, ordinary
                              or extraordinary, foreseen or unforeseen. If due
                              to a future change in the method of taxation, any
                              franchise, income or profit tax shall be levied
                              against Lessor in substitution for, or in lieu of,
                              or in addition to, any tax which would otherwise
                              not constitute a Real Estate Tax, such franchise,
                              income or profit tax shall be deemed to be a Real
                              Estate Tax for the purposes hereof. Any franchise,
                              income or profit tax which is in addition to any
                              tax which would otherwise constitute a Real Estate
                              Tax be deemed a Real Estate Tax if such tax is
                              customarily treated as a Real Estate Tax by the
                              owners of comparable office buildings in the
                              vicinity of the Building. Notwithstanding anything
                              contained herein to the contrary, Lessee shall
                              assume and pay to Lessor in full at the time of
                              paying the Term Basic Rent any excise, sales, use,
                              gross receipts or other taxes (other than an
                              income or excess profits tax) which may be imposed
                              on or measured by such Term Basic Rent or
                              Additional Rent or may be imposed on Lessor or on
                              account of the letting or which Lessor may be
                              required to pay or collect under any law now in
                              effect or hereafter enacted, but only to the
                              extent such taxes are imposed in lieu of or as a
                              substitute for the whole or any part of the
                              impositions that now constitute Real Estate Taxes.

                  (iii) The following shall be executed from Real Estate Taxes:

                        (a)   except as expressly provided herein, any income,
                              excess profit taxes, capital stock taxes, federal
                              or state inheritance taxes, or estate taxes;

                                       37
<PAGE>

                        (b)   any license fee, business license fee, charge,
                              penalty or similar imposition or charge imposed by
                              a taxing authority except and only to the extent
                              that such charge or fee is levied or assessed in
                              lieu of a traditional ad valorem property tax; and

                        (c)   any tax or assessment against property, real or
                              personal, of any firm, person, corporation or
                              other entity other than Lessor, including any
                              Lessee in the Building.

            (D)   Payment.

                  (i)   At any time, and from time to time but no more than
                        twice in any calendar year for each of the escalation
                        categories (unless otherwise required pursuant to a
                        mortgage encumbering the Premises), after the
                        establishment of the Base Period Costs for each of the
                        categories referred to above, Lessor shall advise Lessee
                        in writing of Lessee's Percentage with respect to each
                        of the categories as estimated for the current Lease
                        Year and for each succeeding calendar year or
                        proportionate part thereof if the last period prior to
                        the Lease's termination is less than twelve (12) months
                        as then known to Lessor, and thereafter, Lessee shall
                        pay as Additional Rent, Lessee's percentage of the
                        excess of these costs over the Base Period Costs for the
                        then current period affected by such advice (as the same
                        may be periodically revised by Lessor as additional
                        costs are incurred, subject to the terms and conditions
                        hereof) in equal installments along with the payment of
                        Monthly Basic Rent on the first day of each month, such
                        new rates being applied to any months for which the
                        Monthly Basic Rent shall have already been paid which
                        are affected by the Operating Cost Escalation and/or
                        Utility and Energy Cost Escalation and/or Tax Escalation
                        Costs above referred to, as well as the unexpired months
                        of the current period, the adjustment for the then
                        expired months to be made at the payment of the next
                        succeeding installment of Monthly Basic Rent, all
                        subject to final adjustment at the expiration of each
                        calendar year.

                  (ii)  The Base Period Costs during the calendar year in which
                        the Expiration Date occurs shall be prorated based on
                        the number of days during such calendar year that are
                        within the Term.

            (E)   Books and Records. Lessor shall maintain books of account
                  which shall be open to Lessee and its representatives at all
                  reasonable times so that

                                       38
<PAGE>

                  Lessee can determine that such Operating, Utility, Energy and
                  Tax Costs have, in fact, been paid or incurred. Lessor shall,
                  for at least one (1) year after the end of the year in
                  question, keep files containing all such books, contracts,
                  instruments and other records with respect to such costs and
                  expenses. Lessee and/or Lessee's authorized employees,
                  accountants, auditors, agents or attorneys shall have the
                  right, upon reasonable notice to Lessor, to review, audit and
                  verify any and all such books, contracts, instruments and/or
                  records and to verify all monthly rent and/or any Additional
                  Rent. No such review or audit shall extend to periods of time
                  preceding the Rent Commencement Date, except to the extent
                  that any Operating Costs, Real Estate Taxes, Fuel and
                  Utilities Costs or Electric Costs related to such period are
                  or were being charged to Lessee, or form a material part of
                  the calculations relating to expenses or costs being charged
                  to Lessee. Lessor to the extent available shall furnish
                  Lessee, along with any bill or invoice relating to Real Estate
                  Taxes, with copies of the Real Estate Tax bill(s) applicable
                  thereto. Any disagreement with respect to any one or more of
                  said charges if not satisfactorily settled between Lessor and
                  Lessee with three (3) months after notice of such dispute is
                  served by either party, shall be referred by either party to
                  an independent certified public accountant to be mutually
                  agreed upon, and if such an accountant cannot be agreed upon,
                  the American Arbitration Association may be asked by either
                  party to select an arbitrator, whose decision on the dispute
                  will be final and binding upon both parties, who shall jointly
                  share any cost of such arbitration. Pending resolution of said
                  dispute, Lessee shall pay to Lessor the sum so billed by
                  Lessor subject to its ultimate resolution as aforesaid.

            (F)   Right of Review. Once Lessor shall have finally determined
                  said Operating, Utility and Energy or Tax Costs at the
                  expiration of a Lease Year, then as to the item so
                  established, Lessee shall only be entitled to dispute said
                  charge as finally established for a period of six (6) months
                  after such charge is finally established and communicated in
                  writing to Lessee, and Lessee specifically waives any right to
                  dispute any such charge at the expiration of said six (6)
                  month period.

            (G)   Occupancy Adjustment. If, with respect to Operating Cost
                  Escalation, as established in Subsection 22(A) hereof, and the
                  Utility and Energy Cost Escalation, as established in
                  Subsection 22(B) hereof, the Building is not ninety-five (95%)
                  percent occupied during the establishment of the respective
                  Base Periods, then the Base costs incurred with respect to
                  said Operating Cost or Utility and Energy Cost shall be
                  adjusted during any such period within the Base period so as
                  to reflect ninety-five (95%) percent occupancy. Similarly, if,
                  during any calendar year or

                                       39
<PAGE>

                  proportionate part thereof subsequent to the Base Period the
                  Building is less than ninety-five (95%) percent occupied then
                  the actual costs incurred for Operating Cost and Utility and
                  Energy Cost shall be increased during any such period to
                  reflect ninety-five (95%) percent occupancy so that at all
                  times after the Base Period, the Utility and Energy Cost or
                  Operating Cost shall be actual costs, but in the event less
                  than ninety-five (95%) percent of the Building is occupied
                  during all or part of the calendar year involved, the Utility
                  and Energy Cost and Operating Cost shall not be less than that
                  which would have been incurred and ninety-five (95%) percent
                  of the Building been occupied. The aforesaid adjustment shall
                  only be made with respect to those items that are in fact
                  affected by variations in occupancy levels. To the extent any
                  Operating Cost or Utility and Energy Cost is separately billed
                  or metered or paid for directly by any Building lessee, to
                  include but not be limited to Lessee, or for which Lessor
                  receives reimbursements, said space shall be considered vacant
                  space for purposes of the aforesaid adjustment.
                  Notwithstanding anything to the contrary contained in this
                  Lease, Lessor shall not include in its calculation of
                  Operating Costs or Utility and Energy Costs any costs for
                  services not provided for Lessee's benefit, either solely or
                  in connection with such services provided to other tenants at
                  the Building.

            (H)   Lessee shall pay to Lessor, as Additional Rent, within ten
                  (10) days after being invoiced, such amounts charged by Lessor
                  for any Common Facilities services provided to accommodate (at
                  Lessee's request) Lessee's sole use of the Building after
                  Building Hours. Such amounts shall be billed monthly, at a
                  rate equal to the number of hours during such prior month that
                  such services, if any, are provided for Lessee's exclusive use
                  of the Building after Building Hours, such dollar amount to be
                  reasonably determined by Lessor's engineer, from time-to-time.

23. LESSEE'S ESTOPPEL.

            (A)   Each party hereto (as applicable, the "Certifying Party")
                  shall, from time to time, within fifteen (15) days of the
                  other party's written request (the "Requesting Party"),
                  execute, acknowledge and deliver to such Requesting Party a
                  written statement certifying that the Lease is unmodified and
                  in full force and effect, or that the Lease is in full force
                  and effect as modified and listing the instruments of
                  modification; the dates to which the Monthly Basic Rent and
                  Additional Rent and charges have been paid; and, to the best
                  of such Certifying Party's knowledge, whether or not the
                  Requesting Party is in default hereunder, and if so,
                  specifying the nature of the default and any such other
                  information as the Requesting Party may request. It is
                  intended that any such statement delivered pursuant to this

                                       40
<PAGE>

                  Section may be relied on by a prospective purchaser of
                  Lessor's interest or mortgagee of Lessor's interest or
                  assignee of any mortgage of Lessor's interest or a permitted
                  assignee or subtenant of Lessee.

            (B)   The Certifying Party's failure to deliver such statement
                  within such time shall be conclusive upon such Certifying
                  Party that: (i) this Lease is in full force and effect and not
                  modified except as such Requesting Party may represent; (ii)
                  not more than one (1) installment of Monthly Basic Rent has
                  been paid in advance; (iii) there are no such defaults; and
                  (iv) notice to such Certifying Party shall be sent to such
                  Certifying Party's mailing address as set forth in this Lease.
                  Notwithstanding the presumptions of this Section, such
                  Certifying Party shall not be relieved of its obligation to
                  deliver said statement.

24. HOLDOVER TENANCY. If Lessee holds possession of the Premises after the Term
of this Lease, Lessee shall become a Lessee from month to month under the
provisions herein provided, but at a Monthly Basic Rent equal to the greater of
the fair market value of the Premises or two hundred (200%) percent of the
Monthly Basic Rent payable during the last full calendar month of the Term and
without the requirement for demand or notice by Lessor to Lessee demanding
delivery of possession of said Premises (but Additional Rent shall continue as
provided in this Lease), which sum shall be payable in advance on the first day
of each month, and such tenancy shall continue until terminated by Lessor, or
until Lessee shall have given to Lessor, at least thirty (30) days prior to the
intended date of termination, a written notice of intent to terminate such
tenancy, which termination date must be as of the end of a calendar month. The
time limitations described in this Section 24 shall not be subject to extension
for Force Majeure. Nothing herein contained shall be deemed to be a consent or
waiver by Lessor to a holdover by Lessee after the expiration or sooner
termination of this Lease. Lessee shall be liable for any and all damages
incurred by Lessor as a direct result of Lessee holding over following the
expiration or sooner termination of this Lease.

25. RIGHT TO SHOW PREMISES. Lessor may show the Premises to prospective
purchasers and mortgagees; and, during the twelve (12) months prior to
termination of this Lease, to prospective Lessees, during Building Hours on
reasonable notice to Lessee. Lessee shall be entitled to have a representative
accompany Lessor at the appointed time of entry; provided that such does not
unreasonably interfere with or prevent Lessor from taking the aforementioned
actions.

26. LESSEE IMPROVEMENT WORK AND LESSEE ALLOWANCE.

            (A)   Prior to June 30, 1999 (or in the event of delay caused by
                  Force Majeure, September 30, 1999, provided Lessee provides
                  Lessor with written notice explaining the circumstances
                  causing the completion delay), Lessee shall complete or cause
                  to be completed the work described in the first sentence

                                       41
<PAGE>

                  of subsection 21(A) and on Exhibit E annexed hereto (as the
                  same may be modified from time-to-time, subject to Lessor's
                  reasonable approval, the "Lessee Improvement Work"). Prior to
                  commencing any work at the Premises, Lessee, at its expense,
                  shall cause to be prepared and shall deliver to Lessor space
                  plans for the Lessee Improvement Work. Such space plans shall
                  be subject to the prior written approval of Lessor, which
                  approval shall not be unreasonably withheld or delayed. Upon
                  approval of the space plans for the Lessee Improvement Work,
                  Lessee shall cause construction plans and specifications (as
                  the same may be modified from time-to-time, subject to
                  Lessor's reasonable approval, the "Plans and Specifications")
                  for the Lessee Improvement Work to be prepared by an architect
                  mutually agreeable to the parties, it being agreed by Lessor
                  that CUH2A, Inc. is an acceptable architect. The Plans and
                  Specifications shall be subject to the prior written approval
                  of Lessor, which approval shall not be unreasonably withheld
                  or delayed. Lessee shall prepare a list of general contractors
                  and subcontractors from which Lessee will solicit bids for the
                  Lessee Improvement Work. Such list shall be delivered to
                  Lessor for its written approval, which approval shall not be
                  unreasonably withheld or delayed and shall be conveyed to
                  Lessee within seven (7) business days after receipt of such
                  list from Lessor. Upon Lessor's request, Lessee shall provide
                  Lessor with proof that such general contractors are bondable
                  by a surety company acceptable to Lessor.

            (B)   Except for the Lessee Allowance, Lessee shall be reasonable
                  for all hard and soft costs and expenses with respect to the
                  design and construction of the Lessee Improvement Work. All
                  Lessee Improvement Work shall be performed in strict
                  accordance with the Plans and Specifications approved by
                  Lessor (other than insubstantial changes), in compliance with
                  the provisions of Section 6 of this Lease, in a good and
                  workmanlike manner and in strict compliance with all
                  applicable ordinances, laws, rules and regulations and the
                  requirements of all insurance policies covering the Building,
                  which requirements shall be communicated to Lessee. Lessee
                  hereby guaranties completion of all Lessee Improvement Work,
                  in strict accordance with the provisions of this Section 26.
                  Upon completion of the Lessee Improvement Work, Lessee or
                  Lessee's contractor(s) shall obtain all governmental and
                  quasi-governmental permits, approvals, authorizations and
                  certificates required to perform the Lessee Improvement Work,
                  Lessee or Lessee's contractor(s) shall obtain final signoff(s)
                  from all applicable governmental and quasi-governmental
                  authorities with respect to the Lessee Improvement Work and
                  shall promptly deliver copies thereof to Lessor.

                                       42
<PAGE>

            (C)   Lessor hereby agrees to contribute towards the hard and soft
                  costs of the Lessee Improvement Work, a sum equal to: (a) the
                  lesser of: (i) the product of the Premises Area and Fifteen
                  Dollars and 00/100 ($15.00) or (ii) the actual out-of-pocket
                  costs and expenses incurred by Lessee for the design and
                  construction of the Lessee Improvement Work (except for the
                  costs and expenses incurred by Lessee to upgrade the Demised
                  Premises' electrical capacity to approximately 800 amps at
                  480/277 volts); and (b) in the event Lessee upgrades the
                  Demised Premises' electrical capacity as permitted by this
                  Lease, a portion of the actual out-of-pocket costs and
                  expenses incurred by Lessee up to an amount not to exceed
                  seven thousand five hundred dollars ($7,500) as follows: (i)
                  one hundred percent (100%) of such costs and expense up to the
                  first three thousand dollars ($3,000), (ii) fifty percent
                  (50%) of such costs and expenses, if any, in excess of the
                  first three thousand dollars ($3,000), up to twelve thousand
                  dollars ($12,000), and (ii) zero percent (0%) of such costs
                  and expenses, if any, in excess of twelve thousand dollars
                  ($12,000) (the sum of the amounts described in clauses (a) and
                  (b) is referred to herein as the "Lessee Allowance"). Lessee
                  may include in the hard and soft costs, architect, engineer
                  and other consultant fees, general contractor costs, permits,
                  furniture relocation and assembly and reupholstery of
                  furniture. Following final completion of the Lessee
                  Improvement Work, Lessor shall disburse the Lessee Allowance
                  to Lessee within thirty (30) days of Lessee's request and upon
                  the furnishing of a final certificate of occupancy issued by
                  the applicable governmental authority, appropriate lien
                  waivers and the as-built Plans and Specifications for the
                  Lessee Improvement Work certified by the supervising
                  architect. Except for the Lessee Allowance, Lessor shall have
                  no obligation to make any improvements, alterations or
                  decorations to the Premises or any contributions or credits in
                  respect thereof.

27. WAIVER OF JURY TRIAL/NON-MANDATORY COUNTERCLAIMS.

      IF LESSOR COMMENCES ANY SUMMARY PROCEEDINGS OR AN ACTION FOR NONPAYMENT OF
RENT, LESSEE SHALL NOT INTERPOSE ANY NON-MANDATORY COUNTERCLAIM OF ANY NATURE OR
DESCRIPTION IN ANY SUCH PROCEEDINGS OR ACTION. LESSEE AND LESSOR BOTH WAIVE A
TRIAL BY JURY OF ALL ISSUES ARISING IN ANY ACTION OR PROCEEDING BETWEEN THE
PARTIES HERETO OR THEIR SUCCESSORS, UNDER OR CONNECTED WITH THIS LEASE, OR ANY
OF ITS PROVISIONS.

28. LATE CHARGE. In addition to such other amounts to be paid by Lessee
following a default by Lessee under this Lease, Lessee, at Lessor's option,
shall pay as Additional Rent a "Late Charge" of four (4%) percent (but in no
event to exceed the maximum rate permitted by

                                       43
<PAGE>

applicable law) of any installment of Monthly Basic Rent or Additional Rent paid
more than fifteen (15) days after the due date thereof for each monthly period
or portion thereof that the same remains unpaid, such Late Charge to cover the
extra expense involved in handling delinquent payment.

29. INSURANCE.

            (A)   Lessee's Insurance.

                  (i)   Lessee covenants that during the entire Term hereof, at
                        its sole cost and expense, Lessee shall obtain, maintain
                        and keep in full force and effect the following
                        insurance:

                        (a)   "All Risk" property insurance against fire, theft,
                              vandalism, malicious mischief, sprinkler leakage
                              and such additional perils as are now, or
                              hereafter may be, included in a standard extended
                              coverage endorsement from time to time in general
                              use in the State of New Jersey upon property of
                              every description and kind owned by Lessee and/or
                              under Lessee's care, custody or control located in
                              the Building or within the Office Building Area or
                              for which Lessee is legally liable or installed by
                              or on behalf of Lessee, including by way of
                              example and not by way of limitation, all Lessee
                              Improvement Work, furniture, fixtures, fittings,
                              installations and any other personal property.

                        (b)   Commercial General Liability Insurance coverage
                              (on an occurrence basis form) to include personal
                              injury, bodily injury, broad form property damage,
                              operations hazard, blanket contractual liability,
                              naming Lessor and Lessor's mortgagee or trust deed
                              holder and ground Lessor (if any and if required
                              by prior written notice from Lessor to Lessee) as
                              additional named insureds in an amount per
                              occurrence of not less than Five Million and
                              00/100 ($5,000,000.00) Dollars combined single
                              limit bodily injury and property damage by either
                              a policy for underlying coverage policy or in
                              combination with an excess coverage policy.

                        (c)   Business interruption insurance in such amounts as
                              will reimburse Lessee for direct or indirect loss
                              of earnings attributable to all perils commonly
                              insured against by prudent lessees or assumed by
                              Lessee pursuant to this

                                       44
<PAGE>

                              Lease or attributable to prevention or denial of
                              access to the Premises, Building or Office
                              Building Area as a result of such perils.

                        (d)   Worker's Compensation insurance in form and amount
                              as required by law.

                        (e)   Any other form or forms of insurance or any
                              increase in the limits of any of the aforesaid
                              enumerated coverages or other forms of insurance
                              as Lessor or the mortgagees or ground lessors (if
                              any) of Lessor may reasonably require from time to
                              time if in the reasonable opinion of Lessor or
                              said mortgagees or ground Lessors said coverage
                              and/or limits become inadequate or less than that
                              commonly maintained by comparable Lessees in
                              comparable buildings in the Piscataway, New Jersey
                              area.

                  (ii)  All insurance policies required pursuant to this
                        Subsection 29(A) shall be underwritten by insurers rated
                        A-(VIII) or better by A.M. Best Company who are licensed
                        to do business in the State of New Jersey and shall be
                        in form reasonably satisfactory from time to time to
                        Lessor. A certificate evidencing that such insurance is
                        in effect shall have been delivered to Lessor prior to
                        the date hereof. Such insurance certificate will provide
                        an undertaking by the insurers to notify Lessor and the
                        mortgagees or ground Lessors (if any) and of which
                        Lessee has notice of Lessor in writing not less than
                        thirty (30) days prior to any material change, reduction
                        in coverage, cancellation, or other termination thereof.
                        The foregoing notwithstanding, in the event that
                        Lessee's insurer's Best's rating is less than A-(VIII),
                        then Lessee may have such insurer underwrite the
                        aforesaid insurance but same shall be written with no
                        deductible.

                  (iii) In the event of damage to or destruction of the Building
                        and/or Premises, and such damage or destruction entitles
                        either Lessor or Lessee to terminate this Lease pursuant
                        to Section 9 hereof and the Lease is so terminated, then
                        such portion of Lessee's net insurance proceeds relating
                        to the Lessee Improvement Work and other leasehold
                        improvements and alterations which are so attached to
                        the Building that, had such damage not occurred, they
                        could not be removed without substantial damage to the
                        Building (but not Lessee's trade fixtures, equipment,
                        Removable Improvements, furniture or other personal
                        property of Lessee in the Premises)

                                       45
<PAGE>

                        ("Lessee's Improvement Proceeds"), shall be allocated as
                        follows: (a) first, to Lessor an amount up to but not
                        more than the unamortized portion of the Lessee
                        Allowance paid to Lessee (computed on a straight-line
                        basis over the initial Term of this Lease), and (b) the
                        balance, if any, to Lessee. If the termination of the
                        Lease is due to damage to the Building, and if the
                        Premises have not been so damaged, Lessee will
                        relinquish to Lessor, in accordance with and subject to
                        the provisions subsection 5(C) of this Lease, all Lessee
                        Improvement Work and other leasehold improvements and
                        alterations which are so attached to the Building that,
                        had such damage not occurred, they could not be removed
                        without substantial damage to the building (but not
                        Lessee's trade fixtures, Removable Improvements,
                        equipment, furniture or other personal property of
                        Lessee in the Premises). In the event of damage to or
                        destruction of the Building and/or Premises and such
                        damage or destruction does not entitle Lessor and Lessee
                        to terminate this Lease pursuant to Section 9 hereof
                        and/or both elect not to do so, then Lessee's
                        Improvement Proceeds shall be allocated as follows: (x)
                        first, to Lessor an amount equal to the lesser of the
                        Lessee Allowance paid to Lessee, or an amount equal to
                        the Lessee Improvement Proceeds amount times a fraction
                        where (a) the numerator is the Lessee Allowance, and (b)
                        the denominator is the total cost of the Lessee
                        Improvement work, which shall be retained by Lessor
                        (subject to the provisions of the following sentence),
                        and (y) the balance, if any, to Lessee to be used for
                        Lessee's restoration obligations hereunder. To the
                        extent that any of Lessee's Improvement Proceeds are
                        paid to Lessor, such proceeds shall be held by Lessor in
                        trust, in an interest-bearing account and provided no
                        Event of Default has occurred and is continuing,
                        disbursed to Lessee following final completion of such
                        restoration work by Lessee, subject to the same
                        conditions for disbursement of the Lessee Allowance as
                        set forth in Section 26(C) of this Lease.

                  (iv)  Lessee agrees that it will not keep or use in or upon
                        the Premises or within the Building or Office Building
                        Area any article which is prohibited by any insurance
                        policy in force from time to time covering the Building
                        or Office Building Area of which Lessee has knowledge
                        unless Lessee pays for any increase in insurance
                        premiums directly resulting therefrom and provided that
                        such increase is based upon competitive insurance
                        industry rates. In the event Lessee's occupancy or
                        conduct of business in or on the Premises or Building or
                        Office Building area, whether or not

                                       46
<PAGE>

                        Lessor has consented to the same, directly results in
                        any increase in premiums for insurance carried from time
                        to time by Lessor with respect to the Building or Office
                        Building Area, Lessee shall, within ten (10) days from
                        the date of Lessor's invoice therefor, (a) pay such
                        increase in premiums as Additional Rent, or (b) directly
                        communicate with the appropriate insurer in order to
                        dispute such increased premium charged to Lessor,
                        provided, however, that in the event that Lessee so
                        disputes such increased premium, Lessee shall pay to
                        Lessor the full amount of such charges and Lessor, if
                        Lessee is successful in negotiating a reduction in such
                        premium charges, or the refund thereof, shall promptly
                        reimburse Lessee for the proportionate amount of such
                        reduction or refund within ten (10) days after Lessor
                        recovers such adjustments. If Lessee ceases the activity
                        that resulted in the increase in premium, then provided
                        the insurer reduces the premium, Lessee will receive a
                        corresponding reduction. In determining whether
                        increased premiums are a direct result of Lessee's use
                        and occupancy, a schedule issued by the organization
                        computing the insurance rate on the Building or Office
                        Building Area showing the components of such rate shall
                        be conclusive evidence of the items and charges making
                        up such rate, subject to the provisions hereof. Lessee
                        shall promptly comply with all reasonable requirements
                        of the insurance authority or of any insurer now or
                        hereafter in effect relating to the Building, Office
                        Building Area or Premises.

                  (v)   If any insurance policy carried by Lessor or Lessee
                        shall be canceled or cancellation shall be threatened or
                        the coverage thereunder reduced or threatened to be
                        reduced in any material way by reason of the use or
                        occupation of the Premises, Office Building Area or
                        Building or any part thereof by Lessee or any assignee
                        or sublessee of Lessee or anyone permitted by Lessee to
                        be upon the Premises, other than for the Permitted Use,
                        and if Lessee fails to remedy the conditions giving rise
                        to said cancellation or threatened cancellation or
                        reduction in coverage on or before the earlier of (a)
                        seventy-two (72) hours after notice thereof from Lessor,
                        or (b) prior to said cancellation or reduction becoming
                        effective, Lessee shall be in default hereunder and
                        Lessor shall have all of the remedies available to
                        Lessor pursuant to this Lease. Lessor represents and
                        warrants to Lessee that, as of the date hereof, Lessor
                        has notified its insurance company of Lessee's intended
                        use and occupancy of the Premises as described in the
                        definition of "Permitted Uses" and, to the Lessor's
                        actual knowledge, such use and occupancy by Lessee is
                        acceptable to Lessor's insurer and will

                                       47
<PAGE>

                        not adversely impact the maintenance or coverage of any
                        of Lessor's insurance policies covering the Building.

      (B)   Lessor's Insurance. Lessor covenants and agrees that throughout the
            Term it will insure the Building (excluding any property with
            respect to which Lessee is obligated to insure pursuant to
            Subsection 29(A)(i)(a) above) against damage by fire and standard
            extended coverage perils and public liability insurance in such
            reasonable amounts with such reasonable deductibles as required by
            any mortgagee or ground Lessor (if any), or if none, as would be
            carried by a prudent owner of a similar building in the area;
            provided, however, that Lessor shall at all times during the Term of
            this Lease keep and maintain (i) insurance against loss by fire and
            hazards covered by extended coverage in an amount at least equal to
            80% of the insurable value of the Building, (ii) comprehensive
            general liability insurance, including personal injury and property
            damage coverage, with limits at least equal to those required by
            Lessee hereunder, and (iii) rental abatement insurance against
            abatement of loss of rent in case of fire or other casualty or
            cause. Lessor may, but shall not be obligated to, take out and carry
            any other forms of insurance as it or the mortgagee or ground Lessor
            (if any) of Lessor may require or reasonably determine available.
            All insurance carried by Lessor on the Building or Office Building
            Area shall be included as an Operating Expense pursuant to
            Subsection 22(A). Notwithstanding its inclusion as an Operating
            Expense or any contribution by Lessee to the cost of insurance
            premiums by Lessee as provided herein, Lessee acknowledges that it
            has no right to receive any proceeds from any such insurance
            policies carried by Lessor except as otherwise provided herein.
            Lessee further acknowledges that the exculpatory provisions of this
            Lease as set forth in Section 35 and the provisions of Subsection
            29(A) as to Lessee's insurance are designed to insure adequate
            coverage as to Lessee's property and business without regard to
            fault and to avoid Lessor obtaining similar coverage for said loss
            for its negligence or that of its agents, servants or employees
            which could result in additional costs includable as part of
            Operating Expenses which are payable by Lessee. Lessor will not
            carry insurance of any kind on any Lessee Improvement Work or on any
            of Lessee's furniture or furnishings, or on any fixtures, equipment,
            appurtenances or improvements of Lessee under this Lease and Lessor
            shall not be obligated to repair any damage thereto or replace the
            same.

      (C)   Waiver of Subrogation. Any property insurance policy, which either
            party obtains in connection with the Premises, Building or Office
            Building Area shall include a clause or endorsement denying the
            insurer any rights of subrogation against the other party (i.e.
            Lessor or Lessee) for all perils covered by said policy.

                                       48
<PAGE>

30. NO OTHER REPRESENTATIONS. No representations or promises shall be binding on
the parties hereto except those representations and promises contained herein or
in some future writing signed by the party making such representation(s) or
promise(s).

31. QUIET ENJOYMENT. Lessor covenants that if, and so long as, Lessee pays the
Term Basic Rent, and any Additional Rent as herein provided, and performs the
covenants hereof, Lessor shall do nothing to affect Lessee's right to peaceably
and quietly have, hold and enjoy the Premises for the Term herein mentioned,
subject to the provisions of this Lease and to any mortgage or deed of trust to
which this Lease shall be subordinate, but subject to any of Lessee's rights
under any nondisturbance agreement.

32. INDEMNITY.

      (A)   Lessee is and shall be, except as otherwise provided herein, in
            control and possession of the Demised Premises as provided herein,
            and Lessor shall not be liable for any injury or damage to any
            property or to any person happening on or about the Demised
            Premises, or for any injury or damage to the Demised Premises, nor
            to any property of Lessee, or of any other person contained therein,
            unless such injury or damage is caused by or attributable to the
            gross negligence or willful misconduct of Lessor, its agents,
            servants, employees, contractors, licensees, or invitees.

      (B)   Lessee shall indemnify and save Lessor harmless against and from all
            liabilities, claims, suits, fines, penalties, damages (except for
            consequential damages), losses, fees, costs and expenses (including
            reasonable attorneys' fees) which may be imposed upon, incurred by
            or asserted against Lessor by reason of:

            (i)   Any work or thing done by Lessee, its agents or employees in,
                  on or about the Demised Premises or any part thereof,
                  including, but not limited to (except as otherwise agreed to
                  in writing by the other Building tenants, pursuant to Section
                  6 hereof), the interruption and/or diminution of Building
                  services provided to other tenants in the Building;

            (ii)  Any use, occupation, condition, operation by Lessee, its
                  agents or employees of the Demised Premises or any part
                  thereof or any occurrence in, on or about the Demised Premises
                  not caused by or attributable to the gross negligence or
                  willful misconduct of Lessor, its agents, servants, employees,
                  contractors, licensees, or invitees;

            (iii) The negligence or willful misconduct of Lessee or any
                  sublessee or any employees, licensees or invitees of Lessee
                  occurring anywhere within the Premises, the Building or the
                  Building Office Area;

                                       49
<PAGE>

            (iv)  Any accident, injury (including death) or damage, unless
                  caused by the gross negligence or willful misconduct of
                  Lessor, its agents, servants, employees, contractors,
                  licensees or invitees, to any third party or property owned by
                  someone other than Lessee and not under the care, custody or
                  control of the Lessee occurring in, on or about the Demised
                  Premises; and

            (v)   Any failure on the part of Lessee to perform or comply with
                  any of the covenants, agreements, terms or conditions
                  contained in this Lease.

      (C)   The provisions of this Section 32 shall survive expiration or
            earlier termination thereof.

      (D)   Lessor shall indemnify and save Lessee harmless against and from all
            liabilities, claims, suits, fines, penalties, damages (except for
            consequential damages), losses, fees, costs and expenses (including
            reasonable attorneys' fees) which may be imposed upon, incurred by
            or asserted against Lessee by reason of the gross negligence or
            willful misconduct of Lessor or any employee, servant, agent, or
            contractor of Lessor.

33. APPLICABILITY TO HEIRS AND ASSIGNS. The provisions of this Lease shall apply
to, bind and inure to the benefit of Lessor and Lessee and their respective
heirs, successors, legal representatives and assigns, provided that nothing
herein shall be deemed to waive the provisions of Section 7 hereof. It is
understood that the term "Lessor" as used in this Lease means only the owner, a
mortgagee in possession or a master lessor of the Building and/or Building Area,
so that in the event of any sale of the Building and/or Building Area or of any
lease thereof or if a mortgagee shall take possession of the Premises, the
Lessor named herein shall be and hereby is entirely freed and relieved of all
covenants and obligations of Lessor hereunder accruing thereafter, and it shall
be deemed without further agreement that the purchaser, the ground lessee of the
Building, or the mortgagee in possession has assumed and agreed to carry out any
and all covenants and obligations of Lessor hereunder.

34. PARKING SPACES. Lessee's occupancy of the Demised Premises shall include the
use of those unassigned parking spaces as enumerated in the Preamble. Lessee
shall, upon request by Lessor, promptly furnish to Lessor the license numbers of
the cars operated by Lessee and its sublessees, licensees, invitees (on a
regular basis), concessionaires, officers and employees. If any vehicle of
Lessee, or of any sublessee, licensee, concessionaire, or of their respective
officers, agents or employees, is parked in any part of the Common Facilities
other than the employee parking area(s) designated therefor by Lessor, Lessee
shall pay to Lessor such reasonable charge as may be fixed by Lessor from time
to time. All amounts due under the provisions of this Section shall be deemed to
be Additional Rent. Nothing contained herein shall be deemed to impose any
obligation on Lessor to police the parking area. In no event shall the ratio or
parking spaces available for Lessee's use to square footage leased by less than
1 space per 250 rentable square feet.

                                       50
<PAGE>

35. LESSOR'S EXCULPATION.

      (A)   Except as otherwise provided herein, Lessor shall not be liable to
            Lessee for any loss suffered by Lessee including, but not limited to
            (i) loss of or injury to Lessee or to Lessee's property or that for
            which Lessee is legally liable including but not limited to theft or
            burglary; or (ii) that which results from or is incidental to the
            furnishing of or failure to furnish or the interruption in
            connection with the furnishing of any service which Lessor is
            obligated to furnish pursuant to this Lease; or (iii) any
            interruption to Lessee's business. Nothing contained in the
            preceding sentence shall be deemed to limit Lessor's liability
            (excluding liability for consequential damages) resulting from
            Lessor's gross negligence or willful misconduct; provided that in no
            event shall Lessor be liable for any damage to improvements,
            furniture, fixtures, fittings, installations or other property
            covered by (or which should have been covered by) the "All Risk"
            insurance required to be maintained by Lessee pursuant to Section
            29(A)(i)(a) above.

      (B)   The aforesaid exculpatory Section is to induce the Lessor, in its
            judgment, to avoid or minimize covering risks which are better
            quantified and covered by Lessee either through insurance (or
            self-insurance or combinations thereof if specifically permitted
            pursuant to this Lease) thereby permitting potential cost savings in
            connection with the Operating Expenses borne by Lessee pursuant to
            Section 22.

36. RULES OF CONSTRUCTION/APPLICABLE LAW. Any table of contents, captions,
headings and titles in this Lease are solely for convenience of reference and
shall not affect its interpretation. This Lease shall be construed without
regard to any presumption or other rule requiring construction against the party
causing this Lease to be drafted. If any words or phrases in this Lease shall
have been stricken out or otherwise eliminated, whether or not any other words
or phrases have been added, this lease shall be construed as if the words or
phrases so stricken out or otherwise eliminated were never included in this
Lease and no implication or inference shall be drawn from the fact said words or
phrases were so stricken out or otherwise eliminated. Each covenant, agreement,
obligation or other provision of this Lease on either party's part to be
performed, shall be deemed and construed as a separate and independent covenant
of such party, not dependent on any other provision of this Lease. All terms and
words used in this Lease, regardless of the number of gender in which they are
used, shall be deemed to include any other number and any other gender as the
context may require. This Lease shall be governed and construed in accordance
with the laws of the State of New Jersey, without regard for any of its
conflicts of law principles. If any of the provisions of this Lease, or the
application thereof to any person or circumstances, shall to any extent by
invalid or unenforceable, the remained of this Lease, or the application of such
provision or provisions to persons or circumstances other than those as to whom
or which it is held invalid or unenforceable, shall not be affected thereby, and
every provision of this Lease shall be valid and enforceable to the fullest

                                       51
<PAGE>

extent permitted by law. In the event any provision of this Lease provides that
Lessor will not unreasonably withhold its consent or approval to any matter,
Lessee's sole and exclusive remedy, if it disputes whether Lessor unreasonably
withheld its consent, shall be to seek a declaratory judgment as to whether
Lessor unreasonably withholding its consent or approval to any matter.

37. BROKER. Lessor represents and warrants to Lessee that Newmark is Lessor's
sole broker with whom it has dealt or negotiated in bringing about this Lease,
and Lessee represents and warrants to Lessor that CB is Lessee's sole broker
with whom it has dealt or negotiated in bringing about this Lease. Lessor agrees
to pay any and all commission(s) owing to Newmark and CB in connection with this
transaction pursuant to the terms of a separate written agreement between Lessor
and each of Newmark and CB. Lessor and Lessee each hereby agree to indemnify and
hold the other harmless from any breach or claimed breach of their respective
foregoing representations, warranties and covenants.

38. PERSONAL LIABILITY. Notwithstanding anything to the contrary provided in
this Lease, it is specifically understood and agreed, such agreement being a
primary consideration for the execution of this Lease by Lessor, that there
shall be absolutely no personal liability on the part of the Lessor, its
constituent members (to include but not be limited to officers, directors,
partners and trustees), their respective successors, assigns or any mortgagee in
possession (for the purposes of this Section, collectively referred to as
"Lessor"), with respect to any of the terms, covenants and conditions of this
Lease, and that Lessee shall look solely to the equity of Lessor in the Building
and Building Area for the satisfaction of each and every remedy of Lessee in the
event of any breach by Lessor of any of the terms, covenants and conditions of
this Lease to be performed by Lessor, such exculpation of liability to be
absolute and without any exceptions whatsoever.

39. NO OPTION. The submission of this Lease for examination does not constitute
a reservation of or option for the Premises, and this Lease Agreement becomes
effective as a Lease Agreement only upon execution and delivery thereof by
Lessor and Lessee.

40. DEFINITIONS.

      (A)   Lessee's Percentage. The parties agree that Lessee's Percentage, as
            defined in the Preamble, reflects and will be continually adjusted
            to reflect the sum arrived at by dividing the gross square feet of
            the area rented to Lessee (including an allocable share of all
            Common Facilities) as set forth in the Preamble [the numerator],
            plus any additional gross square footage leased from time to time
            pursuant to this Lease, by the total number of gross square feet of
            the entire Building (or additional buildings that may be constructed
            within the Office Building Area) [the denominator], in each case
            measured in accordance with BOMA standards. Lessor and Lessee agree
            that on the date hereof the Building will be deemed to contain
            64,871 rentable square feet. Lessor shall have the right to make
            changes or revisions in the Common Facilities of the Building so as
            to provide additional

                                       52
<PAGE>

            leasing area; provided, however, that such changes shall not
            materially reduce the services Lessor is required to provide Lessee
            hereunder to the terms and conditions of this Lease. Lessor shall
            also, subject to the terms and conditions hereof, have the right to
            construct additional buildings in the Office Building Area for such
            purposes as Lessor may deem appropriate and subdivide the lands for
            that purpose if necessary, and upon so doing, the Office Building
            Area shall become the subdivided lot on which the Building in which
            the Demised Premises is located. If any service provided for in
            Subsection 22(A) or any utility provided for in Subsection 22(B) is
            separately billed or separately metered within the Building and not
            so in the applicable base year, then the square footage so billed or
            metered shall be deemed vacant and if applicable subject to the
            Occupancy Adjustment set forth in Subsection 22(G).

      (B)   Common Facilities. Common Facilities shall include, by way of
            example and not by way of limitation, the non-assigned parking
            areas; lobby; elevator(s), if applicable; fire stairs; public
            hallways; public lavatories; all other general Building facilities
            that service all Building lessees; air conditioning rooms; fan
            rooms; janitors' closets; electrical closets, telephone closets;
            elevator shafts and machine rooms; flues; stacks; pipe shafts; and
            vertical ducts with their enclosing walls relating to services
            provided to all Building lessees. Lessee's use of those Common
            Facilities not open to all Lessees is subject to Lessor's consent.
            Lessor may at any time close temporarily any Common Facilities to
            make repairs or changes therein or to effect construction, repairs
            or changes within the Building or Office Building Area, or to
            discourage non-lessee parking or to prevent the dedication of the
            same, and may do such other acts in and to the Common Facilities as
            in its reasonable judgment may be desirable to improve the
            convenience thereof but shall always in connection therewith
            endeavor to minimize any inconvenience to Lessee. Lessee shall have,
            as appurtenant to the Demised Premises, the right to use, in common
            with other lessees in the Building and the Office Building Area,
            without limitation, the common walkways and driveways necessary for
            access to the Building and the Office Building Area, and all other
            parts of the Building and/or the Office Building Area, designed or
            intended by Lessor for the use of all Building lessees generally.

      (C)   Force Majeure. Force Majeure shall mean and include those situations
            beyond either party's control, including by way of example and not
            by way of limitation, acts of God; accidents; strikes; shortages of
            labor; supplies or materials; inclement weather; or, where
            applicable, the passage of time while waiting, in good faith, for an
            adjustment of insurance proceeds. Any time limits required to be met
            by either party hereunder, whether specifically made subject to
            Force Majeure or not, except those related to the payment of Term
            Basic Rent or Additional Rent and except as to the time periods set
            forth in Section 24, shall, unless specifically stated to the
            contrary elsewhere in this Lease, be automatically extended by the

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<PAGE>

            number of days by which any performance called for is delayed due to
            Force Majeure.

      (D)   Building Hours. As used in this Lease, the Building Hours shall be
            Monday through Friday, 8:00 a.m. to 6:00 p.m., and Saturdays from
            8:00 a.m. to 1:00 p.m., excluding those holidays as set forth on
            Exhibit D attached hereto and made a part hereof, except the Common
            Facilities lighting in the Building and Office Building Area shall
            be maintained for such additional hours as, in Lessor's reasonable
            judgment, is necessary or desirable to insure proper operation of
            the Building and Office Building Area. Notwithstanding the
            foregoing, Lessee shall have access to the Premises seven (7) days
            per week, twenty-four (24) hours per day, three hundred sixty-five
            (365) days per year.

      (E)   Additional Rent. As used in this Lease, Additional Rent shall mean
            all sums in addition to Term Basic Rent payable by Lessee to Lessor
            pursuant to the provisions of this Lease.

41. LEASE COMMENCEMENT. Notwithstanding anything contained herein to the
contrary, Lessee may take possession of the Demised Premises on the date hereof
and Lessee shall be bound by, and comply with all of the provisions of this
Lease, except that Lessee shall not be required to pay any installment of Term
Basic Rent until December 1, 1998, when the first installment of Term Basic Rent
shall be due and payable.

42. NOTICES. Any notice by either party to the other shall be in writing and
shall be deemed to have been duly given only if delivered personally or sent by
registered mail or certified mail in a postpaid envelope addressed or sent by
recognized overnight courier service which provides written evidence of receipt
with next business day delivery specified, if to Lessee, at the following
address: Praecis Pharmaceuticals Incorporated, 1 Hampshire Street, Cambridge,
Massachusetts, 02139-1572, Attn: Chief Financial Officer, with a copy to the
Premises, Attn.: Gary L. Olson, Ph.D., and with a copy to Skadden, Arps, Slate,
Meagher & Flom LLP, One Beacon Street, Boston, Massachusetts, 02108-3194, Attn.:
Kent A. Coit, Esquire; if to Lessor, at Lessor's address as set forth above,
with a copy to the Premises and with a copy to Dechert Price & Rhoads, Attn.:
Glenn D. Blumenfeld, Esq., 4000 Bell Atlantic Tower, 1717 Arch Street,
Philadelphia, Pennsylvania 19103-2793, or, to either at such other address as
Lessee or Lessor, respectively, may designate in writing. Notice shall be deemed
to have been duly given if delivered personally, on delivery thereof, and if
mailed, upon the third (3rd ) day after the mailing thereof or if sent by
overnight courier service, upon the next business day after sending.

43. ACCORD AND SATISFACTION. No payment by Lessee or receipt by Lessor of a
lesser amount than the Monthly Basic Rent and additional charges payable
hereunder shall be deemed to be other than a payment on account of the earliest
stipulated Monthly Basic Rent and Additional Rent, nor shall any endorsement or
statement an any check or any letter

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<PAGE>

accompanying any check or payment for Basic Rent or Additional Rent be deemed an
accord and satisfaction, and Lessor may accept such check or payment without
prejudice to Lessor's right to recover the balance of such Basic Rent and
Additional Rent or pursue any other remedy provided herein or by law.

44. EFFECT OF WAIVERS. No failure by Lessor to insist upon the strict
performance of any covenant, agreement, term or condition of this Lease, or to
exercise any right or remedy consequent upon a breach thereof, and no acceptance
by Lessor of full or partial Monthly Basic Rent or Additional Rent during the
continuance of any such breach, shall constitute a waiver of any such breach or
of such covenant, agreement, term or condition. No consent or waiver, express or
implied, by Lessor or of any breach of any covenant, condition or duty of Lessee
shall be construed as a consent or waiver to or of any other breach of the same
or any other covenant, condition or duty, unless in writing signed by Lessor.

45. TIME OF ESSENCE. Time shall be of the essence with respect to all dates and
time periods set forth in this Lease.

46. MORTGAGEE'S NOTICE AND OPPORTUNITY TO CURE. Lessee agrees to give any
mortgagee and/or trust deed holder, by registered mail or overnight courier, a
copy of any notice of default served upon Lessor, provided that, prior to such
notice, Lessee has been notified in writing (by way of notice of assignment of
rents and leases or otherwise) of the address of such mortgagees and/or trust
deed holders. Lessee further agrees that, if Lessor shall have failed to cure
such default within the time provided for in this Lease, then such mortgagee
and/or trust deed holder shall have an additional thirty (30) days within which
to cure such default, or if such default cannot be cured within that time, then
such additional time as may be reasonably necessary, provided that within such
thirty (30) days, such mortgagee and/or trust deed holder has commenced and is
diligently pursuing the remedies necessary to cure such default (including but
not limited to commencement of foreclosure proceedings if necessary to effect
such cure), in which event this Lease shall not be terminated while such
remedies are being so diligently pursued.

47. LESSOR'S RESERVED RIGHTS. Lessor and Lessee acknowledge that the Premises
are in a Building which is not open to the general public. Access to the
Building is restricted to Lessor, Lessee, their agents, employees and to their
invited visitors. In the event of a labor dispute including a strike, picketing,
informational or associational activities directed at Lessee or any other
Lessee, Lessor and Lessee agree to cooperate in making any reasonably necessary
change in operating conditions to reasonably restrict pedestrian, vehicular or
delivery ingress and egress to a particular location. Additionally, Lessor
reserves unto itself all rights not granted Lessee, including by way of example
and not by way of limitation, the right to change the name by which the Building
is commonly known; provided that, to the extent appropriate, Lessor shall notify
Lessee when Lessor exercises any such right reserved to Lessor. Notwithstanding
the foregoing, Lessor shall not change the name or street address of the
Building except upon sixty (60) days prior written notice to Lessee, except that
if the street address of the Building is

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<PAGE>

modified by an entity other than Lessor or a person, firm, corporation or other
party related to or affiliated with Lessor, including any governmental entity,
the foregoing shall not be applicable.

48. CORPORATE AUTHORITY. Lessee represents and warrants that this Lease and
Lessee's execution of this Lease has been duly authorized and approved by the
Lessee's Board of Directors. The undersigned officers of Lessee, executing this
Lease on behalf of Lessee represent and warrant that they are officers of the
corporation with authority to execute this Lease on behalf of Lessee.
Concurrently with Lessee's execution and delivery of this Lease, Lessee will
provide Lessor with a Secretary's certificate attesting to a corporate
resolution confirming the aforesaid.

49. GOVERNMENT REQUIREMENTS. In the event of the imposition of mandatory
federal, state, or local governmental control, rules, regulations, or
restrictions on the use or consumption of energy or other utilities or with
respect to any other aspect of this Lease during the Term, both Lessor and
Lessee shall be bound thereby.

50. RENEWAL OPTION.

      (A)   Lessee shall have the right to extend the Term of this Lease for two
            additional terms of five (5) years each commencing on the day
            following the expiration of the initial or renewal Term, as
            applicable, of this Lease (hereinafter referred to as the "Rent
            Commencement Date of the Applicable Extension Term") provided that:

            (i)   Lessee shall give Lessor notice (hereinafter the "Extension
                  Notice") of its election to extend the term of this Lease,
                  which notice shall be given at least twelve (12) months prior
                  to the expiration date of the initial Term or first Extension
                  Term of this Lease, as applicable; and

            (ii)

                  (a)   Lessee has not assigned this Lease (other than pursuant
                        to Section 7(C) or in connection with a Provid Research
                        spin-off pursuant to Section 7(A)) or sublet more than
                        fifty percent (50%) of the Demised Premises to another
                        party (other than to a division, subsidiary or affiliate
                        of Lessee) which sublease is then in effect and there is
                        no continuing default, and no event has occurred which
                        with the giving of notice or the passage of time, or
                        both, would constitute a default on the part of Lessee
                        (for purposes of this Section 50, a "Default"), under
                        the Lease as of the time of the giving of the Extension
                        Notice and the Rent Commencement Date of the Applicable
                        Extension Term. Notwithstanding the foregoing, if a
                        Default exists on such date that Lessee gives Lessor an

                                       56
<PAGE>

                        Extension Notice, such notice will not be invalid as a
                        result of the existence of such Default; provided that
                        Lessee cures such Default and delivers evidence thereof
                        to Lessor within sixty (60) days from the date the
                        Extension Notice is given. If Lessee fails to cure such
                        Default and provide Lessor with evidence thereof within
                        such sixty (60) day period, then the Extension Notice
                        shall become null and void upon notice from Lessor to
                        Lessee within seventy (70) days after the date the
                        Extension Notice is given and failure by Lessee to cure
                        the Default within five (5) days thereafter and this
                        Section 50 shall have no further force of effect and
                        shall be deemed deleted from this Lease.

                  (b)   If Lessee timely gives the Extension Notice and the
                        conditions set forth in this subparagraph (ii) have been
                        satisfied or waived by Lessor, Lessee shall be
                        irrevocably bound to lease the Demised Premises
                        during the Applicable Extension Term on the terms
                        and conditions provided in this Section 50, including,
                        without limitation, at the Annual Base Rent
                        determined in accordance herewith.  If Lessee does not
                        timely send an Extension Notice pursuant to this
                        Section 50A, this Section 50 shall have no force or
                        effect and shall be deemed deleted from this Lease.

      (B)   The Annual Basic Rent payable by Lessee to Lessor during the first
            Extension Term shall be increased to ninety-five (95%) percent of
            the fair market rent for the Premises and shall be increased to the
            fair market value of the Premises for the second Extension Term, but
            with the base years for Base Operating Costs, Base Real Estate Taxes
            and Base Utility and Energy Costs being adjusted to the calendar
            year commencing on the January 1 preceding the Rent Commencement
            Date of the Applicable Extension Term. Fair market rent shall be
            determined by Lessor, subject to the right of Lessee to arbitrate
            the amount of fair market rent as hereinafter provided. At least
            twelve (12) months prior to the expiration date of the initial Term
            or first Extension Term, as applicable, but in no event more than
            fifteen (15) months prior to the expiration date of the initial Term
            or first Extension Term, as applicable, Lessee may give Lessor
            notice of its desire to determine Lessor's good faith estimate of
            the fair market rent for the Premises applicable to such Extension
            Term. Within thirty (30) days after Lessor receives such notice,
            Lessor shall give Lessee notice of such estimate.

      (C)

            (i)   In the event Lessee is entitled to extend the Term hereunder,
                  and timely gives the Extension Notice in accordance with the
                  provisions of Section 50A hereof, and Lessee thereafter
                  disputes the fair market rent as

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<PAGE>

                  determined by Lessor pursuant to Section 50B hereof then at
                  any time on or before the date occurring thirty (30) days
                  after Lessee has been notified by Lessor of the fair market
                  rent, Lessee may initiate the arbitration provided for herein
                  by giving notice from Lessee, which notice shall specify the
                  name and address of the person designated to act as an
                  arbitrator on its behalf.

            (ii)  Within ten (10) days after Lessor receives such notice from
                  Lessee, Lessor shall give notice to Lessee specifying the name
                  and address of the person designated to act as an arbitrator
                  on Lessor's behalf. If Lessor fails to notify Lessee of the
                  appointment of Lessor's arbitrator within such ten (10) day
                  period, then Lessee may request the appointment of the second
                  arbitrator in the same manner as hereinafter provided under
                  Paragraph 50C(iii) for the appointment of a third arbitrator
                  in a case where neither the two arbitrators appointed
                  hereunder nor the parties are able to agree upon such
                  appointment.

            (iii) The two arbitrators so chosen shall meet within ten (10) days
                  after the second arbitrator is appointed, and if, within ten
                  (10) days after the second arbitrator is appointed the two
                  arbitrators do not agree upon the fair market rent, they shall
                  together appoint a third arbitrator. In the event of their
                  being unable to agree upon such appointment within fifteen
                  (15) days after the appointment of the second arbitrator, the
                  third arbitrator shall be selected by the Lessor and Lessee if
                  they can agree thereon within a further period of five (5)
                  days. If the Lessor and Lessee do not so agree, then Lessee,
                  on behalf of itself and Lessor and on notice to Lessor made
                  within thirty (30) days after the appointment of the second
                  arbitrator, may request such appointment by the American
                  Arbitration Association (or any successor organization
                  thereto) in accordance with its rules then prevailing or if
                  the American Arbitration Association (or such successor
                  organization) shall fail to appoint said third arbitrator
                  within thirty (30) days after such request is made, then
                  Lessee may apply within thirty (30) days after such thirty
                  (30) day period, on notice to Lessor, to a court of competent
                  jurisdiction for the appointment of such third arbitrator.

            (iv)  Each of the arbitrators selected as herein provided shall have
                  at least ten (10) years experience in the leasing and renting
                  of office space in first class buildings in Middlesex County,
                  New Jersey. In addition, each of the arbitrators shall be an
                  independent party not affiliated in any way with either Lessor
                  or Lessee.

            (v)   If a third arbitrator is chosen as provided in Section 50C
                  above, then such third arbitrator shall select either the fair
                  market rent determined by the

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<PAGE>

                  arbitrator appointed by or for Lessor or the fair market rent
                  determined by the arbitrator selected by Lessee; the third
                  arbitrator may not select any other amount, and may not "split
                  the difference" between the determinations of the arbitrators
                  selected or appointed by or for the parties. The third
                  arbitrator shall so determine the fair market rent of the
                  Demised Premises and render a written certified report of his
                  determination to both Lessor and Lessee within ten (10) days
                  after appointment of the third arbitrator.

            (vi)  Each party shall pay the fees and expenses of the original
                  arbitrator appointed by or for such party, and all other
                  expenses (not including the attorneys fees and similar
                  expenses of the parties which shall be borne separately by
                  each of the parties) of the arbitration shall be borne by the
                  parties equally. If a third arbitrator is selected or
                  appointed, the fees and expenses of the third arbitrator shall
                  be borne equally by parties hereto.

            (vii) In the event Lessee initiates the aforesaid arbitration
                  process and as of the date of expiration of the initial Term
                  or first Extension Term, as applicable, of this Lease, the
                  amount of fair market rent for the applicable Extension Term
                  has not been determined, Lessee shall pay the amount of Rent
                  and Additional Rent payable from Lessor to Lessee hereunder,
                  and when the determination of fair market rent has actually
                  been made, an appropriate retroactive adjustment shall
                  promptly be made effective as of the Rent Commencement Date of
                  the Applicable Extension Term, if any, or the last day of the
                  initial Term or first Extension Term, as applicable.

           (viii) If Lessee fails to timely initiate the arbitration process or
                  fails to timely request the appointment of an arbitrator by
                  the American Arbitration Association (or such successor
                  organization) or by such court of competent jurisdiction, time
                  being of the essence, the Lessor's determination of the fair
                  market rent under Section 50B above shall be conclusive.

      (D)   Intentionally Deleted.

      (E)   If the determination of fair market rent shall be made by
            arbitrators as set forth herein resulting in the Annual Basic Rent
            payable by Lessee during the applicable Extension Term being more
            than one hundred fifteen (115%) percent of the Annual Basic Rent
            payable by Lessee as of the then Expiration Date, then Lessee shall
            have the right, exercisable by notice to Lessee given not later than
            fifteen (15) days after the final determination of fair market rent
            by the arbitrators, to rescind its exercise of the option to renew
            the Term, in which event the Term shall be deemed to expire on the
            later of (i) sixty (60) days after the exercise of such

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<PAGE>

            rescission by Lessee, or (ii) the then Expiration Date. If Lessee
            shall exercise such right of rescission, Lessee shall be responsible
            for the fees and expenses of the arbitrator appointed by Lessor and
            the fees and expenses of any third arbitrator appointed hereunder,
            and, if applicable, any increase in Monthly Basic Rent as set forth
            in Section 24 of this Lease, if Lessee continues to occupy the
            Premises beyond the then Expiration Date.

      (F)   Except as otherwise provided in this Section 50, Lessee's occupancy
            of the Leased Premises during either Extension Term shall be on the
            same terms and conditions as are in effect immediately prior to the
            expiration of the initial Term or first Extension Term, as
            applicable, of this Lease, provided, however, Lessee shall have no
            further right to extend the Term of this Lease beyond the second
            Extension Term (or the first Extension Term, if the renewable option
            is not effectively exercised during the Initial Term).

      (G)   If this Lease is renewed for an Extension Term, then Lessor or
            Lessee can request the other party hereto to execute an instrument
            setting forth the exercise of Lessee's right to extend the Term of
            this Lease and the terms of such extension, including, without
            limitation, the last day of such Extension Term.

      (H)   If Lessee exercises its right to extend the Term of this Lease for
            an Extension Term pursuant to this Section 50, then the word "Term",
            and the phrases "the Term of this Lease" or "the Term hereof", as
            used in this Lease, shall be construed to include, when practicable
            and appropriate, in Lessor's reasonable discretion, the applicable
            Extension Term.

      (I)   For the purpose hereof fair market value shall be the rate a
            prospective lessee would pay for rental of the Premises as of the
            date which is the Rent Commencement Date of the applicable Extension
            Term for the term of such Extension Term, taking into account all
            relevant factors including, without limitation, determined (i) as if
            the Premises were vacant and being placed on the market by Lessor
            for rental to prospective Lessees who are not then occupants of the
            Building, (ii) upon the assumption that the base years for Base
            Operating Costs, Base Real Estate Taxes and Base Utility and Energy
            Costs will be as provided in this Section, (iii) upon the assumption
            that the Premises are to be leased "as is" in its then existing
            condition for the applicable Extension Term on all of the terms
            provided for in this Lease which are applicable to such Extension
            Term, but expressly disregarding any enhancement to the fair market
            rental value of the Premises on account of the value, in their then
            existing condition, of alterations or installations in or to the
            Premises, (iv) after considering costs and expenses (including,
            without limitation, brokerage commissions, lost rental income during
            any vacancy period and rent concessions) saved by Lessor by reason
            of Lessor's not having to find a new Lessee for such space, (v)
            after

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<PAGE>

            considering the nature of the standard work letter or work allowance
            and other concessions and allowances then being offered by Lessors
            of similar spaces in the vicinity to Lessees entering into new
            leases for spaces of similar size and for similar terms and taking
            into account the work letter provided herein, (vi) the age and
            condition of the Building, (vii) the fact that Lessee will not incur
            relocation costs, (viii) the remaining Term of this Lease, as well
            as the portion of the Term then elapsed, (ix) the fact that the
            Building is occupied by two (2) lessees, and (x) by taking into
            account all other applicable circumstances.

51. SIGNS. No sign, advertisement or notice shall be affixed to or placed upon
any part of the Demised Premises which can be seen from the exterior of the
Premises or elsewhere in the Building by the Lessee, except in such manner, and
of such size, design and color as shall be reasonably approved in advance in
writing by the Lessor. Lessee may at its sole cost and expense construct and
maintain exterior signage, as set forth below. In the event Lessor approves any
sign(s) (including the sign(s) permitted to be installed pursuant to the
preceding sentence of this paragraph), Lessee shall, at its expense, keep such
sign(s) in good condition and repair and comply with all applicable governmental
ordinances and regulations related thereto. Lessee shall, at its expense, obtain
and maintain all necessary governmental approvals and permits required for the
erection and maintenance of the sign(s) and shall deliver copies thereof to
Lessor. No later than the last day of the Term, Lessee shall, at Lessee's
expense, remove all signs and repair all injury done by or in connection with
the installation or removal of the sign(s). Lessee shall have the right to
maintain the signs near the locations currently used by Hanover Insurance
Company (or lessee currently in the Building) or other location agreeable to
Lessor, provided that Lessee's signs are comparable in size and design to the
existing Hanover Insurance Company signs. Any material additions, changes or
alterations to such signs shall be subject to the Lessor's prior written
consent, not to be unreasonably withheld or delayed.

52. LESSEE'S RIGHT TO TERMINATE LEASE. Lessee shall have a one time right to
terminate this Lease, such termination to be effective November 30, 2005 by
giving at least twelve (12) months prior written notice, but no more than
fifteen (15) months prior written notice ("Termination Notice") thereof to
Lessor. In the event Lessee exercises its right to terminate the Lease as
provided herein, the Termination Notice shall be accompanied by a certified or
bank check payable to Lessor in the amount equal to One Hundred Fifty Thousand
Dollars ($150,000).

53. RIGHT OF FIRST OFFER.

      (A)   If at any time during the Tenn, Lessor shall desire to lease space
            in the Building (any such space being referred to as the "Offer
            Space"), then (subject to the right of first offer contained in the
            lease between Lessor and Hanover Insurance Company, with respect to
            space in the Building, as the same may be amended, extended, renewed
            or otherwise modified from time to time) Lessor, before Lessor may
            enter into a lease with a potential lessee for such Offer Space,
            shall offer to Lessee the right to include the Offer Space within
            the Premises upon all of

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<PAGE>

            the terms and conditions of this Lease, except as provided for in
            this Paragraph 53A. Lessee's right to lease the Offer Space is
            subject to the condition that, at the time Lessee delivers Lessee's
            Acceptance Notice (as hereinafter defined): (i) not more than
            fifteen percent (15%) of the rentable space of the Demised Premises
            shall have been subleased by Lessee to persons which are not
            affiliates of Lessee (use by Provid Research or any other division
            which is not a separate legal entity of Lessee shall be deemed use
            by Lessee), (ii) and Event of Default shall not have occurred and be
            continuing, and (iii) Lessee shall have unconditionally and
            irrevocably waived in writing its right to terminate this Lease
            pursuant to Paragraph 52 hereof. Any termination, cancellation or
            surrender of Lessee's interest in this Lease prior to the date on
            which Lessee delivers Lessee's Acceptance Notice shall automatically
            terminate Lessee's right to lease any Offer Space. Notwithstanding
            anything herein to the contrary, if there shall be less than three
            (3) years remaining on the Term of this Lease (taking into account
            an Extension Term if Lessee shall have exercised its right to extend
            the Term for such Extension Term), Lessee shall not have any rights
            under this Paragraph 53. By way of example if the initial term is to
            expire in thirty-six (36) months, Lessee may only exercise its
            option for Offer Space if it previously or concurrently delivers an
            Extension Notice.

      (B)   In the event Lessor desires to lease space in the Building, Lessor
            shall deliver a written offer to Lessee (hereinafter "Offer
            Notice"), which shall provide the following information: (i) the
            annual basic rent for the Offer Space, (ii) the location of and the
            number of rentable square feet of space comprising the Offer Space,
            (iii) the estimated delivery date of the Offer Space ("Offer Space
            Delivery Date"), and (iv) any other material business terms relating
            to the lease of the Offer Space. All terms, including the annual
            basic rent, for the Offer Space shall be bona-fide terms.

      (C)   Lessee shall have the right to accept the offer set forth in the
            Offer Notice by delivering to Lessor an unconditional and
            irrevocable written acceptance thereof hereinafter called "Lessee's
            Acceptance Notice") within five (5) business days after Lessee's
            receipt of the Offer Notice. If Lessee does not timely deliver
            Lessee's Acceptance Notice to Lessor within said five (5) business
            day period, or if Lessee timely gives written notice of its
            intention to decline to exercise the right to lease the Offer Space,
            time being of the essence, Lessor shall be free to lease the Offer
            Space to any prospective Lessee on terms and conditions that are not
            materially more favorable to the prospective Lessee than those set
            forth in the Offer Notice. In the event Lessor desires to lease the
            Offer Space to a prospective lessee on terms and conditions that are
            materially more favorable to the Lessee than those set forth in the
            Offer Notice, Lessor shall first comply with the provisions of this
            Paragraph 53 before leasing the space to any prospective lessee.

                                       62
<PAGE>

      (D)   Lessee's timely delivery of Lessee's Acceptance Notice shall be
            deemed an irrevocable and unconditional agreement by Lessee to lease
            the Offer Space on the terms and conditions set forth in this
            Paragraph 53. Lessor shall give Lessee at least ten (10) days prior
            written notice of the estimated Offer Space Deliver Date, which
            estimate may be revised from time to time as appropriate, provided
            that after any such revision Lessee shall receive at least ten (10)
            days' prior written notice of the Offer Space Deliver Date. The
            "Offer Space Rent Commencement Date" shall be the date on which the
            Offer Space Deliver Date shall have occurred.

      (E)   If Lessor is unable to deliver the Offer Space to Lessee on the
            estimated Offer Space Deliver Date due to the holding over or
            retention of possession of a Lessee or sublessee of such space or
            due to other reasons beyond Lessor's reasonable control, the
            estimated Offer Space Delivery Date shall be extended by such period
            of time that Lessor was so delayed. In such event, Lessor shall not
            be subject to any liability for its failure to give possession of
            such space to Lessee, and the validity of this Lease shall not be
            impaired thereby and Lessee shall take possession of the Offer Space
            when such space can be delivered to Lessee. Lessor hereby agrees to
            use its good faith efforts to obtain possession of the Offer Space
            on the estimated Offer Space Deliver Date. Notwithstanding the
            foregoing, in the event that the Lessor is unable to deliver the
            Offer Space within ninety (90) days (subject to extension due to
            Force Majeure, or the acts of omissions of Lessee) from the initial
            estimated Offer Space Deliver Date, then Lessee shall have the right
            to terminate Lessee's acceptance of the Offer Space immediately upon
            notice to Lessor.

      (F)   The following terms and conditions shall apply to the Offer Space:

            (i)   For purposes of calculating Additional Rent applicable to the
                  Offer Space, "Lessee's Percentage Share" with respect to the
                  Offer Space shall be a fraction, the numerator of which is the
                  number of rentable square feet of space in the Offer Space and
                  the denominator of which is the number of rentable square feet
                  of the Building as determined from time to time pursuant to
                  Section 40A hereof

            (ii)  Promptly following the Offer Space Rent Commencement
                  Date, Lessor and Lessee shall enter into a supplementary
                  agreement expressly confirming (a) the increase in the number
                  of square feet in the Premises, (b) the increase in the Annual
                  Basic Rent payable under this Lease, (c) the adjustment to the
                  Lessee Percentage and the Base Year applicable to the Offer
                  Space for purposes of computing Additional Rent, (d) the
                  increase in the number of parking spaces based on 4 parking
                  spaces for each 1000

                                       63
<PAGE>

                  rentable square feet of space in the Offer Space, and (e) the
                  Offer Space Rent Commencement Date.

            (iii) The Annual Basic Rent and Additional Rent (except as expressly
                  set forth in Subsection F above) for the Offer Space shall be
                  payable by Lessee to Lessor commencing on the Offer Space Rent
                  Commencement Date (prorated for any partial month). Commencing
                  as of the Offer Space Deliver Date, all of the terms,
                  covenants and conditions of this Lease (including, but not
                  limited to the term hereof) shall thereafter be effective and
                  applicable in all respects to the Offer Space as if such space
                  had been included as part of the original Leased Premises,
                  except as specifically provided otherwise in this Paragraph
                  53.

            (iv)  Lessee must lease all Offer Space offered by Lessor at any one
                  time if it desires to lease any of such space, unless
                  otherwise agreed by Lessor and Lessee.

54. NON-COMPETE. Lessee hereby covenants and agrees that during the Term of this
Lease and any extension or renewal thereof, Lessee shall not permit the
following activities to occur at the Demised Premises: (i) engage in the
business of underwriting or distributing life insurance, including without
limitation the sale and/or distribution of annuities, variable products and/or
other investment related insurance products; (ii) engage in the business of
underwriting or distributing property and casualty insurance; (iii) engage in
the business of providing retirement plan products and/or services guaranteed
investment products; (v) engage in the business of providing group managed care
benefit programs, or (vi) erect any sign on or adjacent to the Building relating
to any of the foregoing activities.

55. USE OF ADDITIONAL FACILITIES. Lessor shall within thirty (30) days from the
date hereof submit a written request on Lessee's behalf, to Hanover Insurance
Company ("Hanover"), the other current tenant in the Building, asking Hanover to
allow Lessee's employees and invitees to use Hanover's cafeteria. Lessor shall
make reasonable efforts to ensure that people do not smoke in the outdoor area
adjacent to the Demised Premises.

56. REPRESENTATION OF CONDITIONS OF DEMISED PREMISES. LESSOR HAS LET THE DEMISED
PREMISES TO LESSEE IN ITS PRESENT "AS IS" CONDITION, WITHOUT ANY REPRESENTATION
OR WARRANTY OF ANY KIND OR NATURE, EXPLICIT OR IMPLIED, OTHER THAN THOSE
REPRESENTATIONS SPECIFICALLY SET FORTH IN THIS LEASE. IT IS UNDERSTOOD AND
AGREED THAT LESSOR IS UNDER NO DUTY TO MAKE ANY REPAIRS, ALTERATIONS, OR
DECORATIONS AT THE INCEPTION OF THIS LEASE OR AT ANY TIME HEREAFTER, EXCEPT AS
SPECIFICALLY SET FORTH IN THIS LEASE.

                                       64
<PAGE>

57. COUNTERPARTS. This Lease may be executed in any number of counterparts, each
of which taken together shall constitute one and the same original.

                        [signatures appear on next page]

                                       65
<PAGE>

            IN WITNESS WHEREOF, the parties hereto have hereunto set their hands
and seals the day and year first above written.

                        BDG PISCATAWAY, LLC, Lessor

                        By: BDG Piscataway, Inc.

                        By: /s/ Edward Blumenfeld
                            -----------------------------------
                              Name: Edward Blumenfeld
                              Title: President

                        PRAECIS PHARMACEUTICALS INCORPORATED,
                        Lessee

                        By: ___________________________________

                              Name: ___________________________

                              Title: __________________________

                                       66
<PAGE>

            IN WITNESS WHEREOF, the parties hereto have hereunto set their hands
and seals the day and year first above written.

                        BDG PISCATAWAY, LLC, Lessor

                        By: BDG Piscataway, Inc.

                        By: ___________________________________

                              Name: ___________________________

                              Title: __________________________

                        PRAECIS PHARMACEUTICALS INCORPORATED,
                        Lessee

                        By: /s/ Kevin F. McLaughlin
                            -----------------------------------
                              Name: Kevin F. McLaughlin
                              Title: Sr. V.P. and C.F.O.

                                       67
<PAGE>

                                    EXHIBIT A

                                    PREMISES

                            [Map of 10 Knightsbridge]

                                       68
<PAGE>

                                   EXHIBIT A-1

                              OFFICE BUILDING AREA

                         [Map of 10 Knightsbridge Road]

                                       69
<PAGE>

                                    EXHIBIT B

                         BUILDING RULES AND REGULATIONS

1.    Smoking is prohibited in all areas of the Building.

2.    No common areas shall be obstructed nor shall refuse, furniture, boxes or
      other items be placed therein by Lessee or its officers, agents, servants
      or employees, or used for any purpose other than ingress and egress to and
      from the Premises, or for going from one part of the Building to another
      part of the Building. Lessor shall have the right to control and operate
      the public portions of the Building, and the facilities furnished for the
      common use of the Lessees, in such manner as Lessor deems best for the
      benefit of the Lessees generally. No Lessee shall permit the visit to the
      Demised Premises of persons in such numbers or under such conditions as to
      interfere with the use and other public portions or facilities of the
      Building without prior written consent of Lessor. Canvassing, soliciting
      and peddling in the Building are prohibited.

3.    Plumbing, fixtures and appliances shall be used only for the purpose for
      which constructed, no other unsuitable material shall be placed therein.

4.    No sign, directories, posters, advertisements, or notices shall be painted
      or affixed on or to any of the windows or exterior doors, or in corridors
      or other parts of the Building, except in such color, size and style and
      in such places, as shall be first approved in writing by Lessor in its
      discretion. Lessor shall have the right of remove all unapproved signs
      without notice to the Lessee, at the expense of the Lessee. It is further
      understood that furnishings in Lessee's area which are viewed from common
      areas shall be subject to Lessor's approval.

5.    Lessee shall not do or permit anything to be done in or about the Building
      or bring or keep anything therein that will in any way increase the rate
      of fire or other insurance on the Building, or on property kept therein or
      otherwise increase the possibility of fire or other casualty.

6.    Lessor shall have the right to prescribed the weight and position of heavy
      equipment or objects which may over stress any portion of the floors of
      the Premises. All damage done to the Building by the improper placing of
      such heavy items will be repaired at the sole expense of Lessee.

7.    Movement in or out of the Building of furniture or office equipment or
      dispatch or receipt by Lessees of any bulky material, merchandise or
      materials through the Building entrances or lobby shall be restricted to
      such hours as Lessor shall

                                       70
<PAGE>

      designate. All such movement shall be under the supervision of Lessor by
      prearrangement with Property Management before performance.

      Such prearrangement initiated by Lessee shall include determination by
      Lessor and subject to this decision and control, as to the time, method,
      and routing of movement and as to limitations for safety or other concern
      which may prohibit any article, equipment or any item from being brought
      into the Building. The Lessees are to assume all risks as to the damage to
      articles moved and injury to persons or public engaged or not engaged in
      such movement, including equipment, property, and personnel of Lessor if
      damaged or injured as a result of an act in connection with carrying out
      this service for a Lessee from time of entering property to completion of
      work; and Lessor shall not be liable for acts of any persons engaged in or
      any damages or loss of any said property or persons resulting from any act
      in connection with such service performed for a Lessee.

8.    Lessee shall notify Property Management when safes or other heavy
      equipment are to be taken in or out of the Building, and such moving shall
      only be done after written permission is obtained from Lessor on such
      conditions as Lessor shall require.

9.    Lessee shall cooperate with Lessor's employees in keeping Premises neat
      and clean. Any person employed by any Lessee to do janitor work within the
      Demised Premises must obtain Lessor's consent and such person shall, while
      in the Building and outside of said Demised Premises, comply with all
      instructions issued by building personnel.

10.   Lessee shall not cause or permit any improper noises in the Building, or
      allow any unpleasant odors to emanate from the Premises, or otherwise
      interfere, injure or annoy in any way other Lessees, or persons having
      business with them.

11.   Each Lessee shall be responsible for all persons for whom he authorizes
      entry into or exit out of the Budding, and shall be liable to the Lessor
      for all acts of such persons.

12.   The Lessor does not maintain or clean suite finishes which are
      non-standard, such as kitchens, bathrooms, wallpaper, special lights, etc.
      However, should the need for repairs arise, the Lessor will arrange for
      the work to be done at the Lessee's expense.

13.   No animals shall be brought into or kept in or about the Building, except
      in the normal course of business.

14.   Except as provided in the Lessee's lease, no machinery of any kind other
      than that which is subject to normal business practices, such as
      typewriters, calculators, and business computers, shall be operated on the
      Premises without the prior written consent of Lessor, nor shall Lessee use
      or keep in the Building any inflammable or

                                       71
<PAGE>

      explosive fluid or substance, or any illuminating materials. No space
      heaters or fans shall be operated in the Building.

15.   No bicycles, motorcycles or similar vehicles will be allowed in the
      Building.

16.   There shall be no marking, painting, drilling into or in any way defacing
      any part of the Demised Premises or the Building. No boring, cutting or
      stringing of wires shall be permitted. Lessee shall not construct,
      maintain, use or operate within the Demised Premises or elsewhere within
      or on the outside of the Building, any electrical device, wiring or
      apparatus in connection with a loud speaker system or other sound system.

17.   Lessor has the right to evacuate the Building in the event of any
      emergency or catastrophe.

18.   No food and/or beverages shall be distributed from the Premises without
      the prior written approval of the Property Management, except in
      connection with the operation of vending machines installed for the
      exclusive use of Lessee's employees or the operation of Lessee's lunch
      room for Lessee's employees permitted under the Lease.

19.   No additional locks shall be placed upon any door without the prior
      written consent of Lessor. All necessary keys shall be surrendered upon
      termination of Lessee's Lease, and Lessee shall then give Lessor or his
      agent an explanation of the combination of all locks on the doors or
      vaults.

20.   Access plates to under floor conduits shall be left exposed. Where carpet
      is installed, carpet shall be cut around access plates. Where Lessee
      elects not to provide removable plates in their carpet for access into the
      under floor duct system, it shall be the Lessee's responsibility to pay
      for the removal and replacement of the carpet for any access needed into
      the duct system at any time in the future.

21.   Lessees will not relocate furnishings or cabinets adjacent to mechanical
      or electrical access panels or over air conditioning outlets so as to
      prevent operating personnel from servicing such units as routine or
      emergency access may require. Cost of moving such furnishings for Lessor
      access will be at Lessee's expense. The lighting and air conditioning
      equipment of the Building will remain the exclusive charge of the Building
      designated personnel.

22.   Lessee shall comply with reasonable parking rules and regulations as may
      be posted and distributed from time to time.

                                       72
<PAGE>

23.   No portion of the Building shall be used for the purpose of sleeping or
      lodging or for any illegal purpose.

24.   Lessor shall not be responsible for lost or stolen personal property,
      money or jewelry from Lessee's leased area or public areas regardless of
      whether such loss occurs when area is locked against entry or not.

25.   All requests for keys, locks or graphics must be submitted in writing to
      the Management Office.

26.   Solicitation of any kind is strictly forbidden unless approved in advance
      by the Management Office.

27.   It is strongly recommended that an A, B, C Multi-Purpose fire extinguisher
      be kept in each Lessee's area in an accessible location.

28.   Lessor reserves the right to rescind any of these rules and regulations
      and to make such other and further rules and regulations as in its
      reasonable judgment shall, from time to time, be needed for the safety,
      protection, care and cleanliness of the Buildings, the operation thereof,
      the preservation of good order therein and the protection and comfort of
      the Lessees and their agents, employees and invitees, which rules and
      regulations, when made and written notice thereof is given to a Lessee,
      shall be binding upon it in like manner as if originally herein
      prescribed.

                                       73
<PAGE>

                                    EXHIBIT C

                                CLEANING SERVICES

                       SPECIFICATIONS FOR PROVID RESEARCH

                                                                      Service

                                                                      Days/Yr

***  ENTRANCE LOBBIES

*    Fully Vacuum all carpets from wall to wall                       260

*    Spot clean door glass and side glass                             260

*    Vacuum walk-off mats                                             260

*    Dust ledges, picture frames and moldings                         260

***  OFFICES - CARPET

*    Empty all trash receptacles and replace liners as necessary      260

*    Remove all collected trash to designated area                    260

*    Dust all horizontal surfaces                                     52

*    Dust all low reach areas                                         52

*    Dust all surfaces above normal reach including sills, ledges,    12
     moldings, shelves, door frames, pictures and vents

*    Spot clean all walls, light switches and doors                   52

*    Vacuum all carpeted traffic lane areas                           260

*    Using tank vacuum or backpack, vacuum corners, edges and         12
     chairs, then traffic vacuum all carpeted areas

*    Dust all venetian blinds                                         4

                                       74
<PAGE>

***  CORRIDORS - CARPET

*    Dust all low reach areas                                         52

*    Dust all surfaces above normal reach, including stills,          12
     ledges, moldings, shelves, door frames, pictures and
     vents

*    Vacuum all carpeted traffic lane areas                           260

*    Using tank vacuum or backpack, vacuum corners, edges             12
     and chairs, then traffic vacuum all carpeted areas

***  RESTROOMS

*    Refill dispensers, empty trash, clean and sanitize all           260
     restroom fixtures, wipe all counters, clean mirrors,
     wipe chrome, spot wipe partitions, sweep and damp mop
     floors using a germicidal cleaner

*    Full clean all showers                                           260

***  KITCHEN - (If applicable)

*    Dust all low reach areas                                         52

*    Dust all surfaces above normal reach including sills,            12
     ledges, moldings, shelves, door frames, pictures and
     vents

*    Wet mop entire area                                              52

*    Using a standard floor machine, spray buff all hard              52
     surface area

*    Strip hard surface floor and recoat with three coats of          4
     floor polish

***  MISCELLANEOUS

*    This represents the minimum amount of supervision the            260
     building may require

                                       75
<PAGE>

LAB SPACE REASONABLY DESIGNATED FROM TIME TO TIME BY THE PARTIES SHALL BE
SPECIFICALLY EXCLUDED FROM THIS EXHIBIT AND LESSEE SHALL CLEARLY MARK SUCH AREAS
IN THE DEMISED PREMISES WHICH ARE NOT TO BE CLEANED BY LESSOR.

                                       76
<PAGE>

                                    EXHIBIT D

                                BUILDING HOLIDAYS

Seven Holidays

Washington's Birthday

Memorial Day

July 4th

Labor Day

Thanksgiving Day

Christmas Day

New Year's Day

                                       77
<PAGE>

                                    EXHIBIT E

                             LESSEE IMPROVEMENT WORK
<PAGE>

PROVID RESEARCH, INC.
10 Knightsbridge Road
Piscataway, NJ

PROJECT DESCRIPTION

The 15,000 square feet of space at 10 Knightsbridge leased by Provid Research,
Inc. will be fit out to accommodate up to 24 researchers and six administrative
employees. The initial phase of work provides laboratory and office space for 12
researchers, general administrative offices and conference space, and laboratory
support space.

The space is organized according to functional and work flow needs. The
administrative and reception functions are at the main entrance. The laboratory
and associated researcher office space occupies the central portion of the
building along with a common library and employee amenity space. Laboratory
support spaces such as chemical storage and the NMR lab are located toward the
rear of the space, near the service entrance. A mechanical room for HVAC,
plumbing and electrical equipment is also at this location.

Current plans call for minimizing the amount of equipment on the roof. It is
expected that two large exhaust fans and a possible air intake serving the air
handling unit in the mechanical room will be located on the roof. Other
miscellaneous penetrations to support required equipment and functions - e.g.,
plumbing vents - will also be provided.

Site work includes a transformer and trenching for a new electrical service and
revisions to existing exterior stairs accommodate a scissors lift near the
service entrance. A chiller may also be located on grade adjacent to the service
entrance. A nitrogen tank will be located near the mechanical room. The only
exterior wall change anticipated at this time is the removal of windows in the
mechanical space and the installation of a louver to supply air to the air
handling unit.

The interior is characterized by open spaces visually connected with interior
glazing. This is not only intended to maximize natural light throughout the
facility, but to reinforce interaction between all staff members. The interior
windows are floor-to-ceiling aluminum or wood frames in offices. Matching frames
will be provided in the labs, but the sills will be +/- 36" above the floor.
Doors will be solid core wood, painted or stained.

Interior partitions will be gypsum board on metal studs in most locations. They
will extend to the underside of the roof deck around the labs and conference
rooms. CMU partitions will enclose the mechanical room for sound control and
maintenance purposes. All will be painted.

Ceilings are primarily 8'-8" to align with the top of the exterior windows,
although the height in the laboratories is 9'-0" with a gypsum board fascia and
soffit constructed above those windows. The ceiling is up to 12'-0" high in a
very limited portion of the space to highlight the library. Lighting will be
primarily recessed deep cell parabolic lens fixtures with fluorescent lamps.

Laboratory casework will be either metal or wood units. Each lab module contains
two eight-foot long fume hoods. Laboratory services include hot and cold water,
nitrogen, vacuum, lab waste and power. All except lab waste will be distributed
overhead. The existing slab will be removed to accommodate the laboratory waste
line.

A single new 25,000 cfm air handling unit will serve both phases of the
laboratories. A VAV system design allows the unit to operate at reduced capacity
until the entire fit-out is complete. This unit will also serve the laboratory
support spaces and will provide some make-up air to the offices.

                                       78
<PAGE>

Office space will be served by the existing air handling unit located on a
mezzanine above the toilet rooms. Its capacity of 15,000 cfm is adequate to
serve most of the office needs with limited supplemental air furnished by the
new unit.

                                       79

<PAGE>

         [Map of Provid Inc. --  10 Knightsbridge Road -- Piscataway, N.J.]

                                       80

<PAGE>

                                   EXHIBIT E-1

                             REMOVABLE IMPROVEMENTS

                                       81
<PAGE>

                                    EXHIBIT F

                         LESSOR'S ENVIRONMENTAL REPORTS

Phase I Environmental Site Assessment dated April 3, 1997 with appendices

March 3, 1997 letter from Vincent Krisk, NJDEP to Hanover Insurance

January 28, 1997 letter from James Bono, NJDEP to Joseph Hudschock, NJ Sorge,
Inc.

January 7, 1997 letter from Todd Huffman, JM Sorge, Inc. to NJDEP with
attachments

Site Investigation Report, dated January, 1997

Phase I Environmental Site Assessment, 10 Knightsbridge Road, Piscataway, New
Jersey, with appendices dated October ___, 1997

                                       82
<PAGE>

                                    EXHIBIT G

             SUBORDINATION, NONDISTURBANCE AND ATTORNMENT AGREEMENT

      This Subordination, Nondisturbance and Attornment Agreement ("Agreement")
dated as of ___________, 1998, is made by and among PRAECIS PHARMACEUTICALS,
INCORPORATED, a Delaware corporation, having an address at 1 Hampshire Street,
Cambridge, Massachusetts 02139-1572 ("Tenant"), and _______________, a
___________________ corporation, having an address of ___________________,
______________________________ ("Lender"), and BDG PISCATAWAY, LLC, a New York
limited liability company, having an address at c/o Blumenfeld Development
Group, Ltd., 6800 Jericho Turnpike, Suite 102E, Syosset, New York 11791-4498
("Landlord").

1.    Recitals.

      1.1 Lease. Tenant is the lessee under a certain lease dated ____, 1998 (as
      may be amended from time to time, the "Lease") of certain premises at 10
      Knightsbridge Road (a/k/a 860 Centennial Avenue), Piscataway, New Jersey
      (the "Leased Premises"), as described in the mortgage referred to below
      (the "Mortgaged Property").

      1.2 Mortgage. Lender is the holder of a Mortgage and Security Agreement
      (the "Mortgage") from Landlord to Lender, covering Landlord's interest in
      the Mortgaged Property, which Mortgage has been recorded at the Recorder's
      Office of Middlesex County, New Jersey.

      1.3 Consideration. In connection with the Mortgage, Lender has required
      that Tenant subordinate Tenant's lien interest in the Mortgaged Property
      under the Lease to the Mortgage and agree to attorn to the purchaser at
      any foreclosure sale of the Mortgaged Property held under the Mortgage.
      Tenant is willing to do so on the terms hereinafter set forth.

2.    Agreements.

      2.1 Covenants Regarding the Lease. Tenant agrees as follows:

            (a)   Tenant will not, without the prior written consent of Lender,
                  pay security deposits, rent or other amounts aggregating at
                  any time (specifically excepting prepayments for excess taxes,
                  operating expenses, utilities or similar charges) more than
                  thirty (30) days in advance under the Lease;

            (b)   Tenant will not, without the prior written consent of Lender,
                  amend or modify the Lease or any of the terms thereof, or,
                  except pursuant to terms of the Lease now existing, cancel,
                  terminate or surrender the Lease;

                                       83
<PAGE>

            (c)   Tenant will not, without the prior written consent of Lender,
                  voluntarily subordinate the Lease to any other lien or
                  encumbrance.

      2.2 Subordination of Lease. Tenant hereby agrees with Lender that the lien
      interest of Tenant under the Lease shall be subject and subordinate to the
      Mortgage and any renewals, extensions, modifications, consolidations or
      replacements thereof and any advances thereunder.

      2.3 Attornment by Tenant. Tenant agrees with Lender that, if the interest
      of Landlord in the Mortgaged Property shall be transferred to and owned by
      Lender or other entity by reason of foreclosure, deed in lieu of
      foreclosure or otherwise, the Lease shall continue as a direct lease
      between Tenant and the Lender or other entity, the Lender or other entity
      shall recognize Tenant as the tenant under the Lease for the unexpired
      balance of the term of said Lease and any extensions or renewals thereof,
      and Tenant shall be bound to Lender or such other entity under all of the
      terms, covenants and conditions of the Lease for the balance of the term
      thereof remaining and any extensions or renewals thereof, with the same
      force and effect as if Lender or such other entity were the lessor under
      the Lease. Tenant hereby attorns to Lender or such other entity as its
      landlord, said attornment to be effective and self-operative without the
      execution of any further instruments on the part of any of the parties
      hereto immediately upon Lender or such other entity succeeding to the
      interest of the Landlord in the Mortgaged Property. Tenant agrees,
      however, upon the election of Lender or such other entity and within
      thirty (30) days of written demand by Lender or such other entity after it
      acquires title to the Mortgaged Property, to execute an instrument in
      recordable form in confirmation of the foregoing provisions.

      2.4 Recognition and Nondisturbance. Lender agrees, with Tenant that, so
      long as Tenant duly and promptly performs all of its obligations under the
      Lease and hereunder, neither Lender nor any person, firm, partnership or
      other entity claiming by, through or under Lender shall, in or after
      taking possession of or acquiring title to the Mortgaged Property through
      foreclosure proceedings, deed in lieu of foreclosure, or otherwise,
      disturb the possession or other rights of Tenant under the Lease, and will
      accept Tenant as lessee under the terms and conditions of, and for the
      entire duration of, the term of the Lease, including any extensions and
      renewals set forth in the Lease and any modifications or amendments
      thereof to which Lender has previously agreed in writing, or which were in
      effect prior to the date hereof. Lender, its successors and assigns, shall
      not, however, be:

            (a)   liable for any breach, act of omission of any prior landlord
                  (including Landlord), except that nothing contained in this
                  Section 2.4(a) shall modify any liability of Lender for any
                  breach, act or omission which first

                                       84
<PAGE>

                  occurs and continues after Lender takes possession of, or
                  acquires title to, the Mortgaged Property;

            (b)   subject to any offset or defense which Tenant might have
                  against any prior landlord (including Landlord), except that
                  nothing contained in this Section 2.4(b) shall modify any
                  right of offset or defense that Tenant may possess for any
                  breach, act of omission which first occurs and continues after
                  Lender takes possession of, or acquires title to, the
                  Mortgaged Property;

            (c)   bound by any payment of rent or additional rent (specifically
                  excepting prepayments for excess taxes, operating expenses,
                  utilities or similar charges) made by Tenant to Landlord more
                  than thirty (30) days in advance;

            (d)   bound by any security deposit which Tenant may have paid to
                  any prior landlord (including Landlord) unless such security
                  deposit has actually been delivered to Lender;

            (e)   bound by any amendment to, modification, extension or
                  termination of the Lease made after the date hereof without
                  the written consent of Lender; provided, however, that the
                  foregoing shall not include, and Lender shall be bound by, any
                  modification, extension or termination of the Lease pursuant
                  to the exercise by Tenant of any option currently contained in
                  the Lease; or

            (f)   bound by any provision in the Lease which obligates the
                  Landlord to erect or complete any building or to perform any
                  construction work or to make any improvements to the Mortgaged
                  Property or the Leased Premises; provided, however, that the
                  foregoing shall not negate any right which Tenant has or may
                  have under the terms of the Lease to terminate said Lease for
                  any failure to complete any construction or any improvements.

Notwithstanding the provisions of Article 2.4, specifically Section 2.4(e),
Lender may, at its election, choose to have the benefits of this Agreement with
respect to any amendment to, modification extension or termination of any Lease
entered into after the date of this Agreement without the written consent of
Lender.

The obligation of Lender to accept the attornment of Tenant and not to disturb
Tenant's possession of the Mortgaged Property under the Lease, as set forth
above, is expressly subject to the Tenant, at the time of Lender's taking
possession of or acquisition of title to the Mortgaged Property, not then being
in default beyond any cure period set forth in the Lease with respect to the
performance of any of Tenant's obligations under the Lease.

                                       85
<PAGE>

      2.5 Lender's Opportunity to Cure Landlord's Defaults. In the event that
      Landlord defaults in the performance or observation of any of the terms,
      conditions or agreements in the Lease, Tenant shall give written notice
      thereof to Lender and Lender shall have the right (but not the obligation)
      to cure such default. Tenant shall not take any action with respect to
      such default under the Lease including, without limitation, any action in
      order to terminate, rescind or avoid the Lease or to withhold any rental
      thereunder, unless Lender, after receipt of such notice, fails to cure, or
      cause to be cured, the specified default within a reasonable time, not to
      exceed thirty (30) days, thereafter; but nothing herein shall be deemed to
      impose any obligation on Lender to cure such default.

      2.6 Lease Conditions. Tenant and Lender agree that this Agreement
      satisfies any and all conditions or requirements in the Lease relating to
      the subordination of the Lease to the Mortgage and the granting of a
      nondisturbance agreement to Tenant by Lender. Any noncompliance with such
      conditions is hereby waived. Tenant and Lender further agree that in the
      event that there is any inconsistency between the terms and provisions
      hereof and the terms and provisions of the Lease dealing with the
      nondisturbance by Lender, the terms and provisions hereof shall be
      controlling.

      2.7 Assignment of Interest and Rents. Tenant acknowledges that Tenant has
      notice that Landlord's interest under the Lease and the rent and all other
      sums due thereunder have been assigned to Lender as part of the security
      for the note secured by the Mortgage. In the event that Lender notifies
      Tenant of a default under the Mortgage and demands that Tenant pay its
      rent and all other sums due under the Lease to Lender, Tenant agrees that,
      following Tenant's receipt of such notice, Tenant shall pay the rent and
      all other sums due under the Lease to Lender. By its execution of this
      Agreement, Landlord irrevocably directs Tenant to comply with this Section
      2.7, notwithstanding any contrary direction, instruction or assertion by
      Landlord. Such compliance shall not be deemed to violate the Lease, and
      Landlord hereby releases Tenant from any and all claims arising out of
      Tenant's compliance with this Section 2.7. Tenant shall be entitled to
      full credit under the Lease for any rent or other sums paid to Lender
      pursuant to this Section 2.7 to the same extent as if such rent or other
      sums were paid directly to Landlord.

      2.8 Election to Terminate. Tenant waives the provision of any statute or
      rule of law now or hereafter in effect which may give or purport to give
      Tenant any right or election to terminate or otherwise adversely affect
      the Lease and the obligations of Tenant thereunder solely by reason of any
      foreclosure proceeding in respect of the Mortgage.

      2.9 Mortgagee's Interest. Anything herein or in the Lease to the contrary
      notwithstanding, in the event that Mortgagee shall acquire title to the
      Mortgaged Property, Mortgagee shall have no obligation, nor incur any
      liability, in excess of Mortgagee's estate or interest, if any, in the
      Mortgaged Property and Tenant shall look exclusively to such estate or
      interest of Mortgagee, if any, in the Mortgaged Property for the payment
      and discharge of any obligations imposed upon Mortgagee hereunder or

                                       86
<PAGE>

      under the Lease, and Mortgagee is hereby released and relieved of any
      other liability hereunder or under the Lease. Tenant agrees that with
      respect to any money judgment which may be obtained or secured by Tenant
      against Mortgagee, Tenant shall look solely to the estate or interest
      owned by Mortgagee in the Mortgaged Property, and the Tenant will not
      collect, or attempt to collect any such judgment out of the other assets
      of Mortgagee.

3.    General.

      3.1 Notices. All notices or other communications required or permitted to
      be given pursuant to this Agreement shall be in writing and shall be
      considered as properly given (i) if mailed by first class United States
      mail, postage prepaid, registered or certified with return receipt
      requested, (ii) by delivering same in person to the intended addressee, or
      (iii) by delivery to Federal Express or another independent, nationally or
      locally recognized, third party commercial delivery service for same day
      or next day delivery. Notice so mailed shall be effective on the earlier
      to occur of (a) the date received, or (b) one business day after delivery
      to Federal Express or such other delivery service, postage prepaid. For
      purposes of notice, the address of Lender shall be the address set forth
      herein or such other address as Lender shall have notified Tenant, in
      writing, in accordance with this Section 3.1, and the address of Tenant
      shall be PRAECIS PHARMACEUTICALS INCORPORATED, 1 Hampshire Street,
      Cambridge, Massachusetts, 02139-1572, Attn: Chief Financial Officer; with
      a copy to the Premises, Attn.: Gary Olson, Ph.D. and with a copy to
      Skadden, Arps, Slate, Meagher & Flom LLP, One Beacon Street, Boston,
      Massachusetts, 02108-3194, Attn.: Kent A. Coit, Esquire or such other
      address as Lender shall have notified Tenant, in writing, in accordance
      with this Section 3.1, with a copy to the Leased Premises; provided,
      however, that either party shall have the right to change its address for
      notice hereunder to any other location within the continental United
      States by the giving of ten (10) days' notice to the other party in the
      manner set forth herein.

      3.2 Captions for Convenience Only. The Article and Section entitlements
      hereof are inserted for convenience of reference only and shall in no way
      alter, modify, or define, or be used in construing the text of such
      Articles or Paragraphs.

      3.3 Successors and Assigns. This Agreement shall be binding upon and inure
      to the benefit of the respective successors and assigns of the parties
      hereto, which in the case of Lender shall expressly include any purchaser
      at a foreclosure sale pursuant to the Mortgage, and such purchaser's
      successors and assign.

      3.4 Applicable Law. This Agreement shall be governed by the laws of the
      state of New Jersey.

                                       87
<PAGE>

      3.5 Modification. This Agreement may not be modified except by an
      amendment or other agreement in writing signed by the parties hereto or
      their respective successors in interest. The terms, covenants and
      conditions contained herein shall inure to the benefit of and be binding
      upon the parties hereto and their respective successors and assigns,
      specifically including but not limited to, Tenant's assignees and
      subtenants, if any, and any purchaser at a sale of the Mortgaged Property
      under or pursuant to the mortgage, include a transfer of title by deed in
      lieu of foreclosure, if any.

                       [Signatures Commence on Next Page]

                                       88
<PAGE>

      WITNESS the execution hereof under seal as of the day and year first above
written.

                                          "Tenant"

                                          PRAECIS PHARMACEUTICALS,
                                          INCORPORATED:

                                          By:   ________________________________

                                                Name: __________________________
                                                Title: _________________________
                                                Hereunto duly authorized

                                          "Lender"

                                          ______________________________________

                                          By:   ________________________________

                                                Name: __________________________
                                                Title: _________________________
                                                Hereunto duly authorized

                                          "Landlord"

                                          BDG PISCATAWAY, LLC:

                                          By:   ________________________________

                                                By: ____________________________
                                                Name: __________________________
                                                Title: _________________________
                                                Hereunto duly authorized

                                       89
<PAGE>

STATE OF ________________________         ss.

                                          ss.

COUNTY OF ______________________          ss.

      The foregoing instrument was ACKNOWLEDGED before me this ___ day
of_________, 20___ by ________________________ the _________ of a
_________________ on behalf of and as the free act and deed of said
_______________.

[SEAL]

                                          ______________________________________

                                          Notary Public, State of ______________

My Commission Expires:                    Printed Name: ________________________

_________________________

                     [Acknowledgments Continue on Next Page]

                                       90
<PAGE>

STATE OF ________________________         ss.

                                          ss.

COUNTY OF ______________________          ss.

      The foregoing instrument was ACKNOWLEDGED before me this ___ day
of_________, 20___ by ________________________ the _________ of a
_________________ on behalf of and as the free act and deed of said
_______________.

[SEAL]

                                          ______________________________________

                                          Notary Public, State of ______________

My Commission Expires:                    Printed Name: ________________________

_________________________

                     [Acknowledgments Continue on Next Page]

                                       91
<PAGE>

STATE OF ________________________         ss.

                                          ss.

COUNTY OF ______________________          ss.

      The foregoing instrument was ACKNOWLEDGED before me this ___ day
of_________, 20___ by ________________________ the _________ of a
_________________ on behalf of and as the free act and deed of said
_______________.

[SEAL]

                                          ______________________________________

                                          Notary Public, State of ______________

My Commission Expires:                    Printed Name: ________________________

_________________________

                                       92

<PAGE>

                                    EXHIBIT H

                       ROOF WARRANTIES CURRENTLY IN EFFECT

                                       93
<PAGE>

                                    FIRESTONE

             MODIFIED BITUMEN STANDARD ROOF SYSTEM LIMITED WARRANTY

Warranty:  #RG000886       FBPCO #  H04335           Square Footage  67,499 s.f.
Building Owner: BLUMENFELD DEVELOPMENT GROUP
Building Identification:  HANOVER INSURANCE
Building Address:          10 KNIGHTSBRIDGE RD
                           PISCATAWAY, NJ 08854
Warranty Period:  TWELVE (12) Years Beginning on 12/22/97
Roofing Contractor:  INTEGRITY ROOFING, INC.                           (62626)

For the warranty period indicated above, Firestone Building Products Company
("Firestone"), Division of Bridgestone/Firestone, Inc., warrants to the Building
Owner ("Owner") above that Firestone will, subject to the Terms, Conditions,
Limitations, and Definitions set forth below, repair any leak in the Firestone
Modified Bitumen Roofing System ("System"). Firestone's repair obligation over
the life of this warranty is limited to the Owner's original cost of the System
installation.

                 TERMS, CONDITIONS, LIMITATIONS, AND DEFINITIONS

1.       The System is limited to mean the Firestone brand membranes, Firestone
         brand insulations, and other Firestone brand accessories when installed
         in accordance with Firestone technical specifications.

2.       In the event any leak should occur in the System: (a) the Owner must
         give written notice to Firestone within thirty (3) days of any
         occurrence of a leak. By notifying Firestone, the Owner authorizes
         Firestone or its designee to investigate the cause of the leak. (b) If
         upon investigation, Firestone determines that the leak is not excluded
         under the Terms, Conditions, Limitations and Definitions set forth
         below, the Owner's sole and exclusive remedy and Firestone's liability
         shall be limited to the repair of the leak; (c) Should the
         investigation reveal that the leak is excluded under the Terms,
         Conditions, Limitations and Definitions set forth below, investigation
         costs shall be paid by the Owner. Failure by Owner to pay for these
         cost shall render this Modified Bitumen Standard Roof System Limited
         Warranty ("Limited Warranty") null and void. If the cause of the leak
         is determined by Firestone to be outside the scope of this Limited
         Warranty, Firestone shall advise the

                                       94
<PAGE>

         Owner of the type and/or extent of repairs required to be made at the
         Owner's expense which, if the Owner property makes, will permit this
         Limited Warranty to remain in effect for the unexpired portion of its
         term. Failure by the Owner to make these repairs in a reasonable manner
         and within a reason able time shall render the unexpired portion of its
         term. Failure by the Owner to make these repairs in a reasonable manner
         and within a reasonable time shall render this Limited Warranty null
         and void. (d) Any dispute, controversy or claim between the Owner and
         Firestone concerning this Limited Warranty shall be settled by final
         and binding arbitration in accordance with the American Arbitration
         Associations's rules for the construction industry.

3.       Firestone shall have no obligation under this Limited Warranty unless
         and until Firestone has been paid in full for all materials, supplies,
         services, warranty costs and other costs which are included in, or
         incidental to, the System.

4.       Firestone shall have no obligation under this Limited Warranty, or an
         other liability, nor or in the future if a leak of damage is cause by
         (a) Natural forces, disasters, or acts of God including, but not
         limited to, winds, hurricanes, tornadoes, hail, lightning, earthquakes,
         atomic radiation, insects, or animals; (b) Any act(s), conduct or
         omission(s) by any person, or act(s) or war, which damages the System
         or which impairs the Membrane's ability to resist leaks (c) Failure by
         the Owner to use reasonable care in maintaining the System, said
         maintenance to include, but not limited to those items listed on the
         reverse side of this Limited Warranty titled "Firestone Roofing Car and
         Maintenance Requirements;" (d) Deterioration or failure of building
         components, including, but not limited to, the roof substrate, walls,
         mortar, HVAC units, etc.: (e) Condensation or infiltration of moisture
         in, through, or around the walls, copings, rooftop hardware or
         equipment, building structure or underlying or surrounding materials;
         (f) any acid, oil, harmful chemical, chemical or physical reaction and
         the like which come in contract with the System, which damages the
         System, or which impairs the System's ability to resist leaks; (g)
         Alterations or repairs to the System not approved in writing by
         Firestone; (h) The architecture, engineering, construction or design of
         the roof, roofing system, or building. Firestone does not undertake any
         analysis of the architecture or engineering required to evaluate what
         type of roof system is appropriate; (i) A change in building use or
         purpose; (j) Failure to give proper notice as set forth in paragraph
         1(a) above; (k) ponded water.

                                       95
<PAGE>

5.       This Limited Warranty shall be transferable subject to Firestone
         inspection, written approval, and payment of the current transfer fee.

6.       During the term of this Limited Warranty, Firestone, its designated
         representative or employees shall have free access to the roof during
         regular business hours. In the event that roof access is limited due to
         security or other restrictions, Owner shall reimburse Firestone for
         all reasonable costs incurred during inspection and/or repair of the
         System which are due to delays associated with said restrictions.
         Owner shall be responsible for the removal and replacement of any
         overburdens, superstrata or overlays, either permanent or temporary, as
         necessary to expose the surface of the System for inspection and/or
         repair.

7.       Firestone's failure to enforce any of the terms or conditions stated
         herein shall not be construed as a waiver of such provision or of any
         other terms and conditions of this Limited Warranty.

8.       This Limited Warranty shall be governed and construed in accordance
         with the laws of the State of Indiana without regard to conflict of
         law.

FIRESTONE DOES NOT WARRANT PRODUCTS INCORPORATED OR UTILIZED IN THIS
INSTALLATION WHICH IS NOT FURNISHED. FIRESTONE SPECIFICALLY DISCLAIMS LIABILITY,
UNDER THE THEORY OF LAW, ARISING OUT OF THE INSTALLATION OR PERFORMANCE OR, OR
DAMAGES SUSTAINED BY OR CAUSED BY, PRODUCTS NOT FURNISHED BY FIRESTONE. THIS
LIMITED WARRANTY SUPERSEDES AND IS IN LIEU OF ALL WARRANTIES OR GUARANTEES
WHETHER WRITTEN OR ORAL, EXPRESS OR IMPLIED, INCLUDING, WITHOUT LIMITATION,
WARRANTIES OR MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THIS
LIMITED WARRANTY SHALL BE THE OWNER'S SOLE AND EXCLUSIVE REMEDY AGAINST
FIRESTONE, AND FIRESTONE SHALL NOT BE LIABLE FOR ANY CONSEQUENTIAL, SPECIAL,
INCIDENT OR OTHER DAMAGES INCLUDING, BUT NOT LIMITED TO, LOSS OF PROFITS OR
DAMAGE TO THE BUILDING OR ITS CONTENTS OR THE ROOF DECK. THIS LIMITED WARRANTY
CANNOT BE AMENDED, ALTERED OR MODIFIED IN ANY WAY EXCEPT IN WRITING SIGNED BY
THE PRESIDENT OF FIRESTONE OR A PERSON TO WHOM HIS AUTHORITY HAS BEEN DELEGATED
IN WRITING. NO OTHER PERSON HAS ANY

                                       96
<PAGE>

AUTHORITY TO BIND FIRESTONE WITH ANY REPRESENTATION OR WARRANTY WHETHER ORAL OR
WRITTEN.

                                FIRESTONE BUILDING PRODUCTS COMPANY

                                By: George Furman
                                AUTHORIZED
                                SIGNATURE:  /s/ George Furman
                                TITLE:  Manager, Product Services

                                       97
<PAGE>

               FIRESTONE ROOFING CARE AND MAINTENANCE REQUIREMENTS
          (For Modified Bitumen Standard Roof System Limited Warranty)

Congratulations on your purchase of a Firestone Roofing System! Your roof is a
valuable asset and as such should be properly maintained. All roofs and roofing
systems require periodic maintenance to perform as designed and to keep your
Limited Warranty in full force and effect.

1.       The roof must be inspected at least twice yearly (in the Spring and
         Fall), and after any severe storms. Record maintenance procedures as
         they occur. Log all access times and parties working on the roof.

2.       Proper maintenance and good roofing practice requires that podded water
         (defined as standing water on the roof forty-eight (48) hours after its
         stops raining) must not be allowed on the roof. Roofs must have slope
         to drain and all drain are must remain clean. Bag and remove all debris
         from the roof since debris on the roof surface with be quickly swept
         into drains by rains. This will allow for proper water run-off and
         avoid overloading the roof with podded water.

3.       The Firestone Roofing System cannot be exposed to acids, solvents,
         greases, oil, fats, chemicals and the like. If the Firestone Roofing
         System is subject to contact with any such materials, contact Firestone
         immediately.

4.       The Firestone Roofing System is designed to be a waterproofing
         membrane. If there is to be roof traffic for any reason, contact your
         Firestone Licenced Applicator before proceeding for the installation of
         approved protective walkways.

5.       Firestone Roofing Membranes may require maintenance of the surface of
         the membrane in order to perform as designed:

         a.       Smooth surface APP roofing membranes require the application
                  of an approved liquid coating, such as Aluminum Roof Coating.
                  If this coating is not applied as part of the initial roofing
                  installation, it must be applied within the first five year s
                  after the roof is installed. In addition, this coating should
                  be maintained as needed to recover any areas of the coating
                  that have blistered, peeled or worn through.

                                       98
<PAGE>

         b.       Granule surfaced APP or SBS roofing membranes require the
                  applica tion of additional roofing granules wherever the
                  original factory application of granules has worn through due
                  to roof traffic or some other event.

6.       All counterflashing, metal work, drains, skylights, equipment curb and
         supports, and any other rooftop accessories functioning in conjunction
         with the Firestone Roofing System must be properly maintained at all
         times. In addition, roof sealants (including, but not limited to,
         Firestone Pourable Sealer and General Purpose Sealant) are not covered
         under this warranty and must be maintained per Firestone Technical
         Specifications.

7.       In any additional equipment is to be installed on your roof (e.g. HVAC
         units, TV antennas, etc.), contact Firestone, in writing, for approval
         before proceeding.

8.       Should there be an addition to the building, requiring tie-in to the
         existing Firestone Roofing System, contact Firestone before proceeding
         to ensure the tie-in is in accordance with Firestone specifications.

9.       Should you have a leak:

         (a)      Check for the obvious: clogged roof drains, loose
                  counterflashings, broken skylights, open grills or vents,
                  broken water pipes.

         (b)      Note conditions resulting in leakage. Heavy or light rain,
                  wind direction, temperature and time of day that the leak
                  occurs are all important clues to tracing roof leaks. Note
                  whether the leak stops shortly after each rain or continues to
                  drip until the roof is dry. If you are prepared with the
                  facts, the diagnosis and repair of the leak can proceed more
                  rapidly.

         (c)      Contact Firestone Warranty Claims at 1-800-451-4511
                  immediately...but please don't call until you are reasonably
                  sure that the Firestone Roofing System is the cause of the
                  leak.

Firestone feels that the preceding requirements will assist you, the building
owner, in maintaining a watertight roof for many years. Remember, your roof is
an invest ment. To maximize your return on this investment, maintenance is not
only essential, but required.

                                       99
<PAGE>

                                    FIRESTONE
                                BUILDING PRODUCTS
                            NOBODY COVERS YOU BETTER.
                525 Congressional Boulevard-Carmel, IN 46032-5607
                  1-800-428-4442 1-317-575-7000 1-317-575-7100

                                      100
<PAGE>

                                    FIRESTONE

NOW THAT YOU HAVE A NEW FIRESTONE
ROOFING SYSTEM...

Congratulations on your purchase of a Firestone Roofing System! Your new roof is
a valuable asset and as such should be properly maintained. All roofs require
periodic maintenance to perform as designed and to keep your Limited Warranty in
full force and effect. The "Firestone Roofing Care and Maintenance Guidelines"
printed on the back of your Firestone Roof System Limited Warranty contain a
number of important items to assist you in maintaining a watertight roof for
many years. These maintenance guidelines recommend that the roof be inspected at
least twice yearly. Although this inspection can be performed by any qualified
person selected by you, FIRESTONE RECOMMENDS THAT AT LEAST ONE INSPECTION EVERY
YEAR BE CONDUCTED BY THE FIRESTONE LICENSED APPLICATOR WHO INSTALLED YOUR ROOF.

Whenever an inspection of the roof is performed, Firestone recommends that the
following items be included:

--------------------------------------------------------------------------------
1.  ROOF CONDITIONS REQUIRING PERIODIC INSPECTION:

Periodic inspection of the following items is very important to assure that the
Firestone Roofing System has not been exposed to conditions not covered by
Firestone's Limited Warranty:

         a. ROOF TRAFFIC & WALKWAYS: As stated in Firestone's System Design
         Instructions for all Firestone Roofing Systems, "Walkways help protect
         the membrane from damage due to necessary roof-top service traffic."
         Please note that walkways should be maintained at all roof access
         points, around all mechanical equipment which requires maintenance and
         at all areas where roof traffic more frequent that once a month is
         anticipated. IF, BECAUSE OF TRAFFIC REQUIREMENTS, WALKWAYS NEED TO BE
         INSTALLED ON YOUR ROOF, CONTACT YOUR FIRESTONE LICENSED APPLICATOR
         BEFORE PROCEEDING.

                                      101
<PAGE>

         b. DISCHARGES: All components of the Firestone roof system must be
         protected from discharges, such as petroleum products, greases, oils
         and fats, acids and the like. If the building will have any such
         discharges, please contact Firestone for suggested methods of
         protection. IF, BECAUSE OF THE PRESENCE OF CHEMICAL DISCHARGES,
         PROTECTION MEASURES ARE RECOMMENDED, CONTACT YOUR FIRESTONE LICENSED
         APPLICATOR BEFORE PROCEEDING.

         c. Ponding Water: Proper maintenance and good roofing practice suggests
         that ponded water (defined as standing water on the roof forty-eight
         (48) hours after it stops raining) should not be allowed on the roof.
         Roofs must have slope to drain and all drain areas must remain clean.
         If podded water areas are observed on the roof that cannot be corrected
         by periodic cleaning of drain areas, contact your Firestone License
         Applicator.

         d. Storms: The roof must be inspected after any severe storm,
         especially after any storm that involves high sustained winds, heavy
         wind gusts or tornado-like conditions. All roof surfaces should be
         inspected for damage caused by wind-blown debris. The roof also should
         be inspected after any hail or ice storm which could damage the roofing
         system. If storm-related damage to the roof system is observed, contact
         your Firestone Licensed Applicator before proceeding.

         e. Moisture Infiltration: It is very important to inspect the roofing
         system for moisture infiltration from sources excluded by Firestone's
         Limited Warranty.

         These sources can include but are not limited to:

                  1. Latent moisture in a pre-existing roofing system or roof
                  insulation remaining beneath the Firestone Roofing System.

                  2. Moisture infiltration in or through building walls,
                  copings, mortar joints and roof-top equipment.

                  3. Condensation of water vapor within the roofing system due
                  to temperature and humidity differentials.

Because inspection for moisture infiltration requires professional roofing
experience, Firestone strongly recommends that this inspection be performed by a
Firestone Licensed Applicator at least once a year.

                                      102
<PAGE>

2. NON-FIRESTONE MATERIALS

In some instances, non-Firestone supplied materials are used in conjunction with
Firestone Roofing Systems. These materials may include, but are not limited to
the following items:

         a. Locally-fabricated sheet metal flashings.

         b. Non-Firestone sealants at roof terminations.

         c. Non-Firestone roof insulations.

         d. Non-Firestone insulation fastening devices, including but not
            limited to roofing screws, insulation plates, construction adhesives
            and roofing asphalt.

         e. Preservative-treated wood nailers and blocking.

         f. Roof drains and drain inserts.

         g. Pre-fabricated roof curbs.

         h. Concrete walkway or ballast pavers.

         i. Stone ballast.

         j. Roof coatings.

         k. Penetration pocket sealants.

Because such items are not warranted by Firestone, it is important for you to
establish an ongoing inspection and maintenance program to assure that the
performance of non-Firestone materials does not adversely affect the
weathertight integrity of the Firestone roofing system. Sheet metal items should
be checked for weathertightness and re-anchored/recaulked as needed. Nailers and
blocking should be checked for soundness, and replaced or re-secured if
necessary. Roof drains and drain inserts should be cleared of any debris.
Sealants should be inspected for shrinking or cracking and replaced as required.
The integrity of roof insulation and insulation attachments should be verified.
Walkway pavers should be checked for cracking or splitting and replaced if
necessary. Ballast stone should be checked for deterioration due to freeze/thaw
conditions. In addition, all ballasted roofs should be inspected for localized
wind displacement of the ballast, especially along perimeter roof areas. In the
event ballast displacement is observed, the ballast should be re-dispersed
uniformly and the addition of larger ballast stones should be considered.

                                      103
<PAGE>

3. FIRESTONE PRODUCTS REQUIRING PERIODIC MAINTENANCE:

Some Firestone roof coatings and sealants require periodic maintenance to assure
long-term performance and to keep Firestone Limited Warranty in full force and
effect. These products include but are not limited to the following items:

         a. Firestone Supplied Coatings.

         b. Firestone S-10 Pourable Sealer.

         c. Firestone General Purpose Sealant.

         d. Firestone Metal Flashing.

Because such items must be maintained to keep the Firestone Limited Warranty in
full force and effect, it is important for you to establish an ongoing
inspection and maintenance program to assure that the performance of these
products does not adversely affect the weathertight integrity of the Firestone
roofing system. Roof coatings should be checked for cracking, peeling or
cracking and recoated as necessary. Sealants should be inspected for shrinkage
or cracking and replaced as required. Firestone metal flashing should be checked
for weathertightness and re-anchored/recaulked as needed. Maintenance to
Firestone products must be performed by a Firestone Licensed Applicator.

4. FIRESTONE PRODUCTS REQUIRING PERIODIC INSPECTION

Although the following Firestone products do not necessarily require periodic
maintenance to assure long-term performance, periodic inspection is very
important to assure that these products have not been exposed to conditions
excluded by Firestone's Limited Warranty:

         a. The Firestone Roofing Membrane should be inspected for tears or
punctures caused by wind storms, falling objects, roof traffic and the like.
If the Firestone membrane is supplied with a factory applied coating, such as
roofing granules, the coating should be inspected for any discontinuities
caused by abrasion from wind, roof traffic or other sources. Tears, punctures
and abrasions to the membrane must be repaired by a Licensed Firestone
Applicator using Firestone specified repair procedures.

         In addition, the membrane should be inspected for any contamination
         from discharges, such as petroleum products, greases, oils and fats,
         acids and the like. If any such discharges are observed on the
         membrane, please contact Firestone for suggested methods of protection.
         If, because of the presence of

                                      104
<PAGE>

         chemical discharges, protection measures are recommended by Firestone,
         contact your Firestone Licensed Applicator before proceeding.

         FIRESTONE WALL FLASHINGS also should be inspected for tears, punctures,
         abrasion and contamination from discharges, following the same
         procedures as for the Firestone Roof Membrane.

--------------------------------------------------------------------------------
5.  ROOF INSPECTIONS AND SAFETY:

Inspection of any roof should be undertaken only by qualified persons who are
familiar with safe roofing practice, including all applicable occupational
health and safety regulations relating to roofing and construction. FIRESTONE
RECOMMENDS THAT ALL ROOF INSPECTIONS BE PERFORMED BY A FIRESTONE LICENSED
APPLICATOR OR A SIMILAR ROOFING PROFESSIONAL.

--------------------------------------------------------------------------------
6.  ARRANGING FOR PERIODIC ROOF INSPECTIONS:

Please note that the cost of periodic inspections of you roof, either by your
Firestone Licensed Applicator or by any other roofing professional, are not
included in the cost of your Limited Warranty. Firestone recommends that you
contact your Firestone Licensed Applicator to obtain a proposal for inspection
and maintenance services.

Firestone feels that the preceding guidelines will help you maintain a
watertight roof for many years. Whenever you have questions concerning your
roofing system, do not hesitate to contact your Firestone Licensed Applicator or
your local Firestone Sales Representative.

                                    FIRESTONE
                                BUILDING PRODUCTS
                            NOBODY COVERS YOU BETTER.
                525 Congressional Boulevard-Carmel, IN 46032-5607
                1-800-428-4442   1-317-575-7000   1-317-575-7100

                                      105
<PAGE>

                          [Graphic regarding roof information]

                                       106

<PAGE>

             [EXHIBIT I -- BUILDING SYSTEM WARRANTIES CURRENTLY IN EFFECT]

                                        [NONE]

                                       107

<PAGE>

                               BDG PISCATAWAY, LLC
                              6800 JERICHO TURNPIKE
                          SYOSSET, NEW YORK 11791-4498

                                                                 August 19, 1998

Praecis Pharmaceuticals Incorporated
1 Hampshire Street
Cambridge, Massachusetts  02139-1572

Attention:  Kevin McLaughlin

            Re:   Lease dated as of the date hereof (the "Lease") by and between
                  BDG Piscataway, LLC ("Lessor") and Praecis Pharmaceuticals
                  Incorporated ("Lessee") for certain space, as more
                  particularly described in the Lease (the "Demised Premises"),
                  in the building (the "Building") located at the property
                  commonly known as 10 Knightsbridge Road, Piscataway, New
                  Jersey (the "Office Building Area")

Dear Mr. McLaughlin:

            Lessor and Lessee have entered into the above-referenced Lease with
respect to the Demised Premises. Capitalized terms used herein and not otherwise
defined shall have the meanings given to them in the Lease. Lessor and Lessee
have agreed to enter into this side letter regarding certain provisions of the
Lease. Notwithstanding anything to the contrary contained in the Lease, lessor
and Lessee, intending to be legally bound, agree as follows:

1.    Lessor agrees that the insurance certificate to be delivered by Lessee
      prior to the date of the Lease, pursuant to paragraph 29(A)(ii) of the
      Lease, may be delivered to Lessor after the date of the Lease, but in no
      event later than the date upon which Lessee takes possession of the
      Demised Premises pursuant to paragraph 41 of the Lease.

2.    Lessee acknowledges and agrees that the work to be performed by Lessor
      pursuant to paragraph 19(A)(v) of the Lease has been completed.

3.    Lessee agrees to pay within 10 days after being invoiced, as Additional
      Rent, the amounts described in Schedule 1 attached hereto and made a part
      hereof, for HVAC service provided, at the request of Lessee (such request
      to be made within a reasonable period of time prior to requiring such
      service), after Building Hours by Lessor to the Demised Premises (if any)
      or to the Building for Lessee's sole benefit.
<PAGE>

4.    Lessor and Lessee each agree to insert the attached Exhibit E-1 into their
      respective counterpart versions of the Lease, which the parties agree is
      hereby incorporated into the Lease.

            Unless explicitly set forth above, all other terms and conditions of
the Lease remain unchanged and in full force and effect. Kindly execute this
letter below to acknowledge your acceptance of the above provisions. This letter
may be executed in counterparts.

AGREED TO AND ACCEPTED BY:

Praecis Pharmaceuticals Incorporated

By:  ___________________________
     Name:
     Title:

BDG Piscataway, LLC

By: BDG Piscataway, Inc.

By:  /s/ David Blumenfeld
     ------------------------------
     Name: David Blumenfeld
     Title: Vice President

<PAGE>

4.    Lessor and Lessee each agree to insert the attached Exhibit E-1 into their
      respective counterpart versions of the Lease, which the parties agree is
      hereby incorporated into the Lease.

            Unless explicitly set forth above, all other terms and conditions of
the Lease remain unchanged and in full force and effect. Kindly execute this
letter below to acknowledge your acceptance of the above provisions. This letter
may be executed in counterparts.

AGREED TO AND ACCEPTED BY:

Praecis Pharmaceuticals Incorporated

By:  /s/ Kevin F. McLaughlin
     -------------------------------
     Name: Kevin F. McLaughlin
     Title: Sr. V.P. and C.F.O.

BDG Piscataway, LLC

By: BDG Piscataway, Inc.

By:  ______________________________
     Name:
     Title:

<PAGE>

                                   Schedule 1

            An amount equal to the product of the Overtime Hours of HVAC service
provided by Lessor at Lessee's request during any given calendar month
multiplied by Fifty Dollars ($50). The foregoing dollar amount shall be subject
to increases from time to time upon at least thirty (30) days prior written
notice from Lessor to Lessee, such increases to reflect actual costs incurred by
Lessor to provide such additional HVAC service after Building Hours at Lessee's
request.

            "Overtime Hours" means the aggregate number of hours electrical
energy is consumed or HVAC service is provided, as applicable, at all hours
other than Building Hours.
<PAGE>

                                   EXHIBIT E-1

                             Removable Improvements

      1.    Laboratory Benches;
      2.    Laboratory Hoods;
      3.    Nitrogen Tanks and Stands; and
      4.    all other items reasonably requested in writing by Lessor to be
            designated as "Removable Improvements" in connection with Lessor's
            approval of Lessee's Plans and Specifications, provided same shall
            be reasonably agreed to in writing by Lessee.
<PAGE>

             SUBORDINATION, NONDISTURBANCE AND ATTORNMENT AGREEMENT

      This Subordination, Nondisturbance and Attornment Agreement ("Agreement")
dated as of August 19, 1998, is made by and among PRAECIS PHARMACEUTICALS,
INCORPORATED, a Delaware corporation, having an address at 1 Hampshire Street,
Cambridge, Massachusetts 02139-1572 ("Tenant"), and MORGAN GUARANTY TRUST
COMPANY OF NEW YORK, a New York banking corporation, having an address of 60
Wall Street, New York, New York 10260-0060 ("Lender"), and BDG PISCATAWAY, LLC,
a New York limited liability company, having an address at c/o Blumenfeld
Development Group, Ltd., 6800 Jericho Turnpike, Suite 102E, Syosset, New York
11791-4498 ("Landlord").

1.    Recitals.

      1.1 Lease. Tenant is the lessee under a certain lease dated August 19,
      1998 (as may be amended from time to time, the "Lease") of certain
      premises at 10 Knightsbridge Road (a/k/a 860 Centennial Avenue),
      Piscataway, New Jersey (the "Leased Premises"), as described in the
      mortgage referred to below (the "Mortgaged Property").

      1.2 Mortgage. Lender is the holder of a Mortgage and Security agreement
      (the "Mortgage") from Landlord to Lender, covering Landlord's interest in
      the Mortgaged Property, which Mortgage has been recorded at the Recorder's
      Office of Middlesex County, New Jersey.

      1.3 Consideration. In connection with the Mortgage, Lender has required
      that Tenant subordinate Tenant's lien interest in the Mortgaged Property
      under the Lease to the Mortgage and agree to attorn to the purchaser at
      any foreclosure sale of the Mortgaged Property held under the Mortgage.
      Tenant is willing to do so on the terms hereinafter set forth.

2.    Agreements.

      2.1 Covenants Regarding the Lease. Tenant agrees as follows:

            (a)   Tenant will not, without the prior written consent of lender,
                  pay security deposits, rent or other amounts aggregating at
                  any time (specifically excepting prepayments for excess taxes,
                  operating expenses, utilities or similar charges) more than
                  thirty (30) days in advance under the Lease.

            (b)   Tenant will not, without the prior written consent of Lender,
                  amend or modify the Lease or any of the terms thereof, or,
                  except pursuant to terms of the Lease now existing, cancel,
                  terminate or surrender the Lease;
<PAGE>

            (c)   Tenant will not, without the prior written consent of Lender,
                  voluntarily subordinate the Lease to any other lien or
                  encumbrance.

      2.2 Subordination of Lease. Tenant hereby agrees with Lender that the lien
      interest of Tenant under the Lease shall be subject and subordinate to the
      Mortgage and any renewals, extensions, modifications, consolidations or
      replacements thereof and any advances thereunder.

      2.3 Attornment by Tenant. Tenant agrees with Lender that, if the interest
      of Landlord in the Mortgaged Property shall be transferred to and owned by
      Lender or other entity by reason of foreclosure, deed in lieu of
      foreclosure or otherwise, the Lease shall continue as a direct lease
      between Tenant and the Lender or other entity, the Lender or other entity
      shall recognize Tenant as the tenant under the Lease for the unexpired
      balance of the term of said Lease and any extensions or renewals thereof,
      and Tenant shall be bound to Lender or such other entity under all of the
      terms, covenants and conditions of the Lease for the balance of the term
      thereof remaining and any extensions or renewals thereof, with the same
      force and effect as if Lender or such other entity were the lessor under
      the Lease. Tenant hereby attorns to Lender or such other entity as its
      landlord, said attornment to be effective and self-operative without the
      execution of any further instruments on the part of any of the parties
      hereto immediately upon Lender or such other entity succeeding to the
      interest of the Landlord in the Mortgaged Property. Tenant agrees,
      however, upon the election of Lender or such other entity and within
      thirty (30) days of written demand by Lender or such other entity after it
      acquires title to the Mortgaged Property, to execute an instrument in
      recordable form in confirmation of the foregoing provisions.

      2.4 Recognition and Nondisturbance. Lender agrees, with Tenant that, so
      long as Tenant duly and promptly performs all of its obligations under the
      Lease and hereunder, neither Lender nor any person, firm, partnership or
      other entity claiming by, through or under Lender shall, in or after
      taking possession of or acquiring title to the Mortgaged Property through
      foreclosure proceedings, deed in lieu of foreclosure, or otherwise,
      disturb the possession or other rights of Tenant under the Lease, and will
      accept Tenant as lessee under the terms and conditions of, and for the
      entire duration of, the term of the Lease, including any extensions and
      renewals set forth in the Lease and any modifications or amendments
      thereof to which Lender has previously agreed in writing, or which were in
      effect prior to the date hereof. Lender, its successors and assigns, shall
      not, however, be:

            (a)   liable for any breach, act or omission of any prior landlord
                  (including Landlord), except that nothing contained in this
                  Section 2.4(a) shall modify any liability of Lender for any
                  breach, act or omission which first occurs and
<PAGE>

                  continues after Lender takes possession of, or acquires title
                  to, the Mortgaged Property;

            (b)   subject to any offset or defense which Tenant might have
                  against any prior landlord (including Landlord), except that
                  nothing contained in this Section 2.4(b) shall modify any
                  right of offset or defense that Tenant may possess for any
                  breach, act or omission which first occurs and continues after
                  Lender takes possession of, or acquires title to, the Mortgage
                  Property;

            (c)   bound by any payment of rent or additional rent (specifically
                  excepting prepayments for excess taxes, operating expenses,
                  utilities or similar charges) made by Tenant to Landlord more
                  than thirty (30) days in advance;

            (d)   bound by any security deposit which Tenant may have paid to
                  any prior landlord (including Landlord) unless such security
                  deposit has actually been delivered to Lender;

            (e)   bound by any amendment to, modification, extension or
                  termination of the Lease made after the date hereof without
                  the written consent of Lender; provided, however, that the
                  foregoing shall not include, and Lender shall be bound by, any
                  modification, extension or termination of the Lease pursuant
                  to the exercise by Tenant of any option currently contained in
                  the Lease; or

            (f)   bound by any provision in the Lease which obligates the
                  Landlord to erect or complete any building or to perform any
                  construction work or to make any improvements to the Mortgaged
                  Property or the Leased Premises; provided, however, that the
                  foregoing shall not negate any right which Tenant has or may
                  have under the terms of the lease to terminate said Lease for
                  any failure to complete any construction or any improvements.

Notwithstanding the provisions of Article 2.4, specifically Section 2.4(e),
Lender may, at its election, choose to have the benefits of this Agreement with
respect to any amendment to, modification extension or termination of any Lease
entered into after the date of this Agreement without the written consent of
Lender.

The obligation of Lender to accept the attornment of Tenant and not to disturb
Tenant's possession of the Mortgaged Property under the Lease, as set forth
above, is expressly subject to the Tenant, at the time of Lender's taking
possession of or acquisition of title to the Mortgaged Property, not then being
in default beyond any cure period set forth in the Lease with respect to the
performance of any of Tenant's obligations under the Lease.

      2.5 Lender's Opportunity to Cure Landlord's Defaults. In the event that
      Landlord defaults in the performance or observation of any of the terms,
      conditions or agreements
<PAGE>

      in the Lease, Tenant shall give written notice thereof to Lender and
      Lender shall have the right (but not the obligation) to cure such default.
      Tenant shall not take any action with respect to such default under the
      Lease including, without limitation, any action in order to terminate,
      rescind or avoid the Lease or to withhold any rental thereunder, unless
      Lender, after receipt of such notice, fails to cure, or cause to be cured,
      the specified default within a reasonable time, not to exceed thirty (30)
      days, thereafter; but nothing herein shall be deemed to impose any
      obligation on Lender to cure such default.

      2.6 Lease Conditions. tenant and Lender agree that this Agreement
      satisfies any and all conditions or requirements in the Lease relating to
      the subordination of the Lease to the Mortgage and the granting of a
      nondisturbance agreement to Tenant by Lender. Any noncompliance with such
      conditions is hereby waived. Tenant and Lender further agree that in the
      event that there is any inconsistency between the terms and provisions
      hereof and the terms and provisions of the Lease dealing with the
      nondisturbance by Lender, the terms and provisions hereof shall be
      controlling.

      2.7 Assignment of Interest and Rents. Tenant acknowledges that Tenant has
      notice that Landlord's interest under the Lease and the rent and all other
      sums due thereunder have been assigned to Lender as part of the security
      for the note secured by the Mortgage. In the event that Lender notifies
      Tenant of a default under the Mortgage and demands that Tenant pay its
      rent and all other sums due under the Lease to Lender, Tenant agrees that,
      following Tenant's receipt of such notice, Tenant shall pay the rent and
      all other sums due under the Lease to Lender. By its execution of this
      Agreement, Landlord irrevocably direct Tenant to comply with this Section
      2.7, notwithstanding any contrary direction, instruction or assertion by
      Landlord. Such compliance shall not be deemed to violate the Lease, and
      Landlord hereby releases Tenant from any and all claims arising out of
      Tenant's compliance with this Section 2.7. Tenant shall be entitled to
      full credit under the Lease for any rent or other sums paid to Lender
      pursuant to this Section 2.7 to the same extent as if such rent or other
      sums were paid directly to Landlord.

      2.8 Election to Terminate. Tenant waives the provision of any statute or
      rule of law now or hereafter in effect which may give or purport to give
      Tenant any right or election to terminate or otherwise adversely affect
      the Lease and the obligations of Tenant thereunder solely by reason of any
      foreclosure proceeding in respect of the Mortgage.

      2.9 Mortgagee's Interest. Anything herein or in the Lease to the contrary
      notwithstanding, in the event that Mortgagee shall acquire title to the
      Mortgaged Property, Mortgagee shall have no obligation, nor incur any
      liability, in excess of Mortgagee's estate or interest, if any, in the
      Mortgaged Property and Tenant shall look exclusively to such estate or
      interest of Mortgagee, if any, in the Mortgaged Property for the payment
      and discharge of any obligations imposed upon Mortgagee hereunder or under
      the Lease, and Mortgagee is hereby released and relieved of any other
      liability hereunder or under the Lease. Tenant agrees that with respect to
      any money judgment
<PAGE>

      which may be obtained or secured by Tenant against Mortgagee, Tenant shall
      look solely to the estate or interest owned by Mortgagee in the Mortgaged
      Property, and the Tenant will not collect, or attempt to collect any such
      judgment out of the other assets of Mortgagee.

3.    General.

      3.1 Notices. All notices or other communications required or permitted to
      be given pursuant to this Agreement shall be in writing and shall be
      considered as properly given (i) if mailed by first class United States
      mail, postage prepaid, registered or certified with return receipt
      requested, (ii) by delivering same in person to the intended addressee, or
      (iii) by delivery to Federal Express or another independent, nationally or
      locally recognized, third party commercial delivery service for same day
      or next day delivery. Notice so mailed shall be effective on the earlier
      to occur of (a) the date received, or (b) one business day after delivery
      to Federal Express or such other delivery service, postage prepaid. For
      purposes of notice, the address of Lender shall be the address set forth
      herein or such other address as Lender shall have notified Tenant, in
      writing, in accordance with this Section 3.1, and the address of Tenant
      shall be PRAECIS PHARMACEUTICALS INCORPORATED, 1 Hampshire Street,
      Cambridge, Massachusetts, 02139-1572, Attn: Chief Financial Officer; with
      a copy to the Premises, Attn: Gary Olson, Ph.D. and with a copy to
      Skadden, Arps, Slate, Meagher & Flom LLP, One Beacon Street, Boston,
      Massachusetts, 02108-3194, Attn: Kent A. Coit, Esquire or such other
      address as Lender shall have notified Tenant, in writing, in accordance
      with this Section 3.1, with a copy to the Leased Premises; provided,
      however, that either party shall have the right to change its address for
      notice hereunder to any other location within the continental United
      States by the giving of ten (10) days' notice to the other party in the
      manner set forth herein.

      3.2 Captions for Convenience Only. The Article and Section entitlements
      hereof are inserted for convenience of reference only and shall in no way
      alter, modify, of define, or be used in construing the text of such
      Articles of Paragraphs.

      3.3 Successors and Assigns. This Agreement shall be binding upon and inure
      to the benefit of the respective successors and assigns of the parties
      hereto, which in the case of Lender shall expressly include any purchaser
      at a foreclosure sale pursuant to the Mortgage, and such purchaser's
      successors and assign.

      3.4 Applicable Law. This Agreement shall be governed by the laws of the
      state of New Jersey.

      3.5 Modification. This Agreement may not be modified except by an
      amendment or other agreement in writing signed by the parties hereto or
      their respective successors in interest. The terms, covenants and
      conditions contained herein shall inure to the benefit
<PAGE>

      of and be binding upon the parties hereto and their respective successors
      and assigns, specifically including but not limited to, Tenant's assignees
      and subtenants, if any, and any purchaser at a sale of the Mortgaged
      Property under or pursuant to the mortgage, include a transfer of title by
      deed in lieu of foreclosure, if any.

      3.6 Counterparts. This Agreement may be executed in any number of
      counterparts, each of which taken together shall constitute one and the
      same original.
<PAGE>

                       [Signatures Commence on Next Page]
<PAGE>

            WITNESS the execution hereof under seal as of the day and year first
above written.

                                    "Tenant"
                                    PRAECIS PHARMACEUTICALS,
                                    INCORPORATED

                                    By: ________________________________________
                                        Name: __________________________________
                                        Title: _________________________________
                                        Hereunto duly authorized

                                    "Lender"
                                    MORGAN GUARANTY TRUST
                                    COMPANY OF NEW YORK

                                    By: /s/ Nancy S. Alto
                                        --------------------------------------
                                        Name: Nancy S. Alto
                                        Title: Vice President
                                        Hereunto duly authorized

                                    "Landlord"
                                    BDG PISCATAWAY, LLC:

                                    By: BDG Piscataway, Inc.

                                        By: /s/ David Blumenfeld
                                            ----------------------------------
                                            Name: David Blumenfeld
                                            Title: Vice President
                                            Hereunto duly authorized
<PAGE>

STATE OF ________________________         ss.

                                          ss.

COUNTY OF ______________________          ss.

      The foregoing instrument was ACKNOWLEDGED before me this ___ day of
____________, 19__ by _____________________________ the _________________ of a
_____________________ on behalf of and as the free act and deed of said
_______________________.

[SEAL]

                                          ______________________________________
                                          Notary Public, State of ______________

My Commission Expires:                    Printed Name: ________________________

_________________________

STATE OF NEW YORK                         ss.

                                          ss.

COUNTY OF NEW YORK                        ss.

      The foregoing instrument was ACKNOWLEDGED before me this 24th day of
August, 1998 by Nancy S. Alto the Vice President of a corporation on behalf
of and as the free act and deed of said corporation.

[SEAL]

                                          /s/ Maryellen Dillon
                                          ------------------------------------
                                          Notary Public, State of New York

My Commission Expires:                    Printed Name: Maryellen Dillon

March 9, 2000

                     [Acknowledgments Continue on Next Page]

<PAGE>

STATE OF NEW YORK                         ss.

                                          ss.

COUNTY OF NASSAU                          ss.

      The foregoing instrument was ACKNOWLEDGED before me this 26th day of
August, 1998 by David Blumenfeld the Vice President of an LLC on behalf of
and as the free act and deed of said LLC.

[SEAL]

                                          /s/ Barbara A. Liotta
                                          ------------------------------------
                                          Notary Public, State of New York

My Commission Expires:                    Printed Name: Barbara A. Liotta

January 20, 2000

<PAGE>

            WITNESS the execution hereof under seal as of the day and year first
above written.

                                    "Tenant"
                                    PRAECIS PHARMACEUTICALS,
                                    INCORPORATED

                                    By: /s/ Kevin F. McLaughlin
                                        --------------------------------------
                                        Name: Kevin F. McLaughlin
                                        Title: V.P. and C.F.O.
                                        Hereunto duly authorized

                                    "Lender"
                                    MORGAN GUARANTY TRUST
                                    COMPANY OF NEW YORK

                                    By: ________________________________________
                                        Name: __________________________________
                                        Title: _________________________________
                                        Hereunto duly authorized

                                    "Landlord"
                                    BDG PISCATAWAY, LLC:

                                    By: BDG Piscataway, Inc.

                                        By: ____________________________________
                                            Name: ______________________________
                                            Title: _____________________________
                                            Hereunto duly authorized
<PAGE>

STATE OF MASSACHUSETTS                    ss.

                                          ss.

COUNTY OF ESSEX                           ss.

      The foregoing instrument was ACKNOWLEDGED before me this 6th day of
August, 1998 by Kevin F. McLaughlin the V.P. and C.F.O. of a corporation on
behalf of and as the free act and deed of said corporation.

[SEAL]

                                        /s/ Mary O'Malley
                                        -------------------------------------
                                        Notary Public, State of Massachusetts

My Commission Expires:                    Printed Name: Mary O'Malley

November 30, 1998

STATE OF ________________________         ss.

                                          ss.

COUNTY OF ______________________          ss.

      The foregoing instrument was ACKNOWLEDGED before me this ___ day of
____________, 19__ by _____________________________the _________________of a
_____________________ on behalf of and as the free act and deed of said
_______________________.

[SEAL]

                                          ______________________________________
                                          Notary Public, State of ______________

My Commission Expires:                    Printed Name: ________________________

_________________________

                     [Acknowledgments Continue on Next Page]
<PAGE>

STATE OF ________________________         ss.

                                          ss.

COUNTY OF ______________________          ss.

      The foregoing instrument was ACKNOWLEDGED before me this ___ day of
____________, 19__ by _____________________________ the _________________ of a
_____________________ on behalf of and as the free act and deed of said
_______________________.

[SEAL]

                                          ______________________________________
                                          Notary Public, State of ______________

My Commission Expires:                    Printed Name: ________________________

_________________________

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