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                                                                    Exhibit 1.18









                             HOBBS BROOK OFFICE PARK

                             Waltham, Massachusetts

                                  OFFICE LEASE

                               ALTAREX, U.S. Corp.

                                303 Wyman Street

                                 March 30, 1998









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                             HOBBS BROOK OFFICE PARK

                             Waltham, Massachusetts

                           LEASE dated March 30, 1998

                                    ARTICLE I

                                 REFERENCE DATA

         1.1  SUBJECTS REFERRED TO

         Each reference in this Lease to any of the following subjects shall be
construed to incorporate the data stated for that subject in this Article.

LANDLORD: 275 Wyman Street Trust, formed under Declaration of Trust dated July
16, 1962 and recorded with the Middlesex South Registry of Deeds in Book 10190,
Page 252, as amended by instrument dated January 17, 1992 and recorded with said
Registry in Book 21748, Page 313, with Trustees Thomas M. Dusel, Robert J.M.
O'Hare, Jr. and Michael D. Bank (as amended, the "Landlord")

LANDLORD'S  ADDRESS:       P.O. Box 9198
                           Waltham, Massachusetts 02254-9198
                           Attention: Real Estate Manager

TENANT:                    ALTAREX, U.S. Corp.

TENANT'S ORIGINAL ADDRESS:                Campus Tower
                                          8625-112 Street;
                                          Edmonton, Alberta
                                          CANADA P6G 2E1

GUARANTOR:                 Altarex Corporation

GUARANTOR'S ORIGINAL ADDRESS:             Campus Tower
                                          8625-112 Street;
                                          Edmonton, Alberta
                                          CANADA P6G 2E1

TERM COMMENCEMENT DATE:  April 1, 1998

TERM EXPIRATION DATE:  March 31, 2001






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ANNUAL FIXED RENT:  $107,887.50

SECURITY DEPOSIT:   NONE

BASE OPERATING EXPENSES PER SQUARE FOOT OF RENTABLE FLOOR AREA: Actual
Landlord's Operating Expenses per square foot of rentable area for calendar year
1998.

BASE TAXES PER SQUARE FOOT OF RENTABLE FLOOR AREA: Actual Landlord's Taxes per
square foot of rentable area for calendar year 1998.

LAND: The land upon which the Building is situated including parking areas,
      garages, drives, walks, landscaped areas and other common areas serving
      the Building.

BUILDING: The entire building known and numbered as 303 Wyman Street, Waltham,
          Massachusetts and all improvements on the Land but excluding any
          parking garage.

TOTAL RENTABLE FLOOR AREA OF BUILDING: 84,612 square feet.

PREMISES:  The space delineated on Exhibit A.

RENTABLE FLOOR AREA OF PREMISES:  3,425 square feet.

PERMITTED USES:            General Office Use

PUBLIC LIABILITY INSURANCE:  $1,000,000.00

BROKER:  R.M. Bradley & Co., Inc. and Lynch, Murphy, Walsh & Partners

TENANT'S AUTHORIZED REPRESENTATIVE:  Richard E. Bagley

         1.2      EXHIBITS

         The following is a list of Exhibits attached to this Lease.

                  Exhibit A:         Plan of Premises.

                  Exhibit B:         [INTENTIONALLY OMITTED]

                  Exhibit C:         Landlord's Cleaning Specifications.







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                  Exhibit D:        Lessee's Estoppel

                  Exhibit E :       Subordination, Non-Disturbance and
                                    Attornment Agreement

                  Exhibit F:        Guaranty of Altarex Corporation


                                    ARTICLE II

                         PREMISES; TERM; RENT; OPERATING
                            EXPENSES; AND ELECTRICITY

         2.1      PREMISES AND EXCLUSIONS

         Landlord hereby leases to Tenant and Tenant hereby leases from Landlord
the Premises. The Premises exclude common areas and facilities of the Building,
including without limitation exterior faces of exterior walls, the common
stairways and stairwells, entranceways and any lobby and courtyard areas,
elevators and elevator wells, fan rooms, electric and telephone closets, janitor
closets, freight elevator vestibules, and pipes, ducts, conduits, wires and
appurtenant fixtures serving other parts of the Building (exclusively or in
common) and other common areas and facilities. If the Premises include less than
the entire rentable area of any floor, then the Premises also exclude the common
corridors, elevator lobby and toilets located on such floor.

         This Lease is subject to all easements, restrictions, agreements, and
encumbrances of record to the extent in force and applicable.

         2.2      APPURTENANT RIGHTS

         Tenant shall have, as appurtenant to the Premises, rights to use in
common (subject to reasonable rules of general applicability to tenants and
other users of the Building from time to time made by Landlord of which Tenant
is given notice): (a) the common lobbies, corridors, stairways, elevators and
loading platform, and the pipes, ducts, conduits, wires and appurtenant meters
and equipment serving the Premises in common with others; (b) common driveways
and walkways necessary for access to the Building; (c) if the Premises include
less than the entire rentable floor area of any floor, the common toilets,
corridors and elevator lobby on such floor and serving the Premises; and (d) all
other areas or facilities in the Building from time to time intended for general
use by Tenant, other Building tenants, and Landlord.

         2.3      RESERVATIONS





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         Landlord reserves the right from time to time, without unreasonable
(except in emergency) interruption of Tenant's use: (a) to install, use,
maintain, repair, replace and relocate for service to the Premises and other
parts of the Building, or either, pipes, ducts, conduits, wires and appurtenant
fixtures, wherever located in the Premises or the Building; and (b) to alter or
relocate any other common facility, including without limitation any lobby and
courtyard areas. Installations, replacements and relocations referred to in
clause (a) above shall be located as far as practicable in the central core area
of the Building, above ceiling surfaces, below floor surfaces or within
perimeter walls of the Premises.

         2.4      TERM

         The Term shall begin at 12:01 a.m. on April 1, 1998

         2.4.1 EXTENSION OPTION. Tenant shall have the option to extend the Term
for one additional three year extension term (the "Extension Term") by notice
given to Landlord at least six months before the Term Expiration Date. Tenant's
election shall be exercised, and Annual Fixed Rent for each Extension Term shall
be determined, as set forth below. If Tenant fails timely to exercise its option
for the Extension Term, Tenant shall have no further extension rights hereunder.

         Tenant's option so to extend the Term shall be void, at Landlord's
election, if Tenant is in default (continuing beyond any applicable cure period)
at the time Tenant elects to extend the Term or at the time the Term would
expire but for such extension. The extension of the Term shall be applicable to
the entire Premises. During the Extension Term, if any, all provisions of this
Lease shall apply except that Tenant shall have no further option to extend the
Term after the Extension Term.

         During the Extension Term, Tenant shall pay Annual Fixed Rent equal to
95% of the then-prevailing market rate for three to five year leases of office
space in the greater Boston, Massachusetts "Metro-West" area comparable to the
Premises in terms of location within a building, finish, age, building quality
and amenities for a tenant of equal size and financial strength as Tenant.

         Landlord shall notify Tenant of its estimate of the prevailing market
rate within ten (10) days after Tenant exercises the extension option. Tenant
shall have the option to accept or reject by written notice Landlord's estimate,
or to withdraw its exercise of the extension option. In the event Tenant rejects
Landlord's estimate then the prevailing market rate shall be arbitrated in
accordance with the following procedure. Each of Landlord and Tenant, within
twenty (20) days after notice by Tenant disputing Landlord's estimate of the
prevailing market rate, shall appoint as an arbitrator an MAI appraiser with at
least ten years experience as an appraiser of Boston office buildings, including
first class suburban office buildings, and shall give notice of such appointment





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to the other party. If either Landlord or Tenant shall fail timely to appoint an
arbitrator, the other may apply to the Boston Office of the American Arbitration
Association ("AAA") for appointment of such an arbitrator if the arbitrator has
not been appointed within five business days after notice of such failure has
been given to the delinquent party. The two arbitrators shall, within five
business days after appointment of the second arbitrator, appoint a third
arbitrator who shall be similarly qualified. If the two arbitrators are unable
to agree timely on the selection of the third arbitrator, then both arbitrators
together may request such appointment from the Boston office of the AAA. The
arbitration shall be conducted in accordance with the Commercial Arbitration
Rules of the AAA insofar as such rules are not inconsistent with the provisions
of this Lease (in which case the provisions of this Lease shall govern), and the
arbitrators shall be charged to reach a majority decision in accordance with the
standards provided in this Lease. The prevailing market rent rate shall be in
accordance with the arbitrators' decision. The cost of the arbitration
(exclusive of each party's witness and attorneys fees, which shall be paid by
such party) shall be borne equally by the parties. If the AAA shall cease to
provide arbitration for commercial disputes in Boston, the second or third
arbitrator, as the case may be, shall be appointed by any successor organization
providing substantially the same services, and in the absence of such an
organization, by a court of competent jurisdiction under the arbitration act of
The Commonwealth of Massachusetts.

         For any portion of the Extension Term, Tenant shall make payment on
account of Annual Fixed Rent at the rate payable for the preceding lease year
and the parties shall adjust for over or under payments within twenty days after
the decision of the arbitrators is announced.

         Promptly after the Annual Fixed Rent is determined for the Extension
Term, Landlord and Tenant shall enter into an amendment of this Lease confirming
the extension of the Term and the new rate for Annual Fixed Rent.

         2.5  ANNUAL FIXED RENT

         Tenant covenants and agrees to pay the Annual Fixed Rent in Section 1.1
to Landlord in advance in equal monthly installments on the first day of each
calendar month during the Term. All payments shall be due without billing or
demand and without deduction, setoff or counterclaim. Tenant shall make payment
for any portion of a month at the beginning or end of the Term. All payments
shall be payable to Landlord at its Address, both as specified in Section 1.1,
or to such other entities at such other places as Landlord may from time to time
designate.

         Without limiting the foregoing, Tenant's obligation so to pay rent, or
to pay any additional charge hereunder, shall not be discharged or otherwise
affected by any law or regulation now or hereafter applicable to the Premises,
or any other restriction on








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Tenant's use, or (except as expressly provided herein) any casualty or taking,
or any failure by Landlord to perform any covenant contained herein, or any
other occurrence; and Tenant waives all rights now or hereafter existing to
terminate or cancel this Lease or quit or surrender the Premises or any part
thereof, or to assert any defense in the nature of constructive eviction to any
action seeking to recover rent or additional charges.

         2.6      ADDITIONAL CHARGES - OPERATING EXPENSES AND TAXES

                  2.6.1 ADDITIONAL CHARGES - GENERAL COVENANT. Tenant covenants
and agrees to pay to Landlord, as additional charges, (i) an amount equal to the
product of (a) the Rentable Floor Area of the Premises and (b) the excess (if
any) of Landlord's Operating Expenses per square foot of Rentable Floor Area
over Base Operating Expenses per Square Foot of Rentable Floor Area and (ii) an
amount equal to the product of (a) the Rentable Floor Area of the Premises and
(b) the excess (if any) of Landlord's Taxes per square foot of Rentable Floor
Area over Base Taxes Per Square Foot of Rentable Floor Area, provided that if
less than the Total Rentable Floor Area of the Building is occupied at any time
during such period, Landlord may extrapolate components of Landlord's Operating
Expenses and Landlord's Taxes as though the Total Rentable Floor Area of the
Building had been occupied at all times during such period.

         Appropriate adjustments (including adjustments in Base Operating
Expenses Per Square Foot of Rentable Floor Area and Base Taxes Per Square Foot
of Rentable Floor Area, which are quoted on an annual basis in Section 1.1)
shall be made for any portion of a year at the beginning or end of the Term or
for any year during which changes occur in the percentage of occupancy of the
Building.

                  2.6.2 PAYMENT. Additional charges for Landlord's Operating
Expenses and Landlord's Taxes under this Section 2.6 shall be paid for any
portion of a month at the beginning of the Term and thereafter in monthly
installments on the first day of each calendar month in amounts reasonably
estimated by Landlord for the then current calendar year. Landlord may from time
to time revise such estimates based on available information relating to
Landlord's Operating Expenses and Taxes or otherwise affecting the calculation
hereunder. Within 90 days after the end of each calendar year, Landlord will
provide Tenant with an accounting of Landlord's Operating Expenses and Taxes and
other data necessary to calculate additional charges hereunder for such calendar
year prepared in accordance herewith and otherwise in accordance with generally
accepted accounting principles. Such statement shall be conclusive between the
parties unless fraudulently prepared except as to matters to which Tenant
objects by written notice to Landlord within 30 days of delivery of the
Landlord's statement of such accounting. Upon issuance thereof, there shall be
an adjustment between Landlord and Tenant for the calendar year covered by such
accounting to the end that Landlord shall







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have received the exact amount of additional charges due hereunder. Any
overpayments by Tenant hereunder shall be credited against the next payments of
additional charges due under this Section 2.6 or refunded to Tenant at the
expiration of the term, provided there are no outstanding amounts due Landlord
under this Lease at such time. Any underpayments by Tenant shall be due and
payable within ten (10) days of delivery of Landlord's statement. With respect
to the calendar year in which the Term ends, the adjustment shall be pro rated
for the portion of the year included in the Term, but shall take place
nevertheless at the times provided in the preceding sentences.

                  2.6.3 "LANDLORD'S OPERATING EXPENSES" - DEFINITION.
"Landlord's Operating Expenses" means all costs of Landlord in owning,
servicing, operating, managing, maintaining, and repairing the Building, and
providing services to tenants including, without limitation, the costs of the
following: (i) supplies, materials and equipment purchased or rented, total wage
and salary costs paid to, and all contract payments made on account of, all
persons engaged in the operation, maintenance, security, cleaning and repair of
the Building and Land, including Social Security, old age and unemployment taxes
and so-called "fringe benefits"; (ii) building services furnished to tenants of
the Building at Landlord's expense (including the types of services provided to
Tenant pursuant to Section 4.1 hereof) and maintenance and repair of and
services provided to or on behalf of the Building performed by Landlord's
employees or by other persons under contract with Landlord; (iii) utilities
consumed and expenses incurred in the operation, maintenance and repair of the
Building including, without limitation, oil, gas, electricity (other than
electricity to tenants in their Premises if Tenant is directly responsible for
payment under this Lease on account of electricity consumed by Tenant), water,
sewer and snow removal; (iv) casualty, liability and other insurance, and
unreimbursed costs incurred by Landlord which are subject to a commercially
reasonable insurance deductible; (v) costs of operating any cafeteria, other
food service facility, or physical fitness facility for use of tenants
generally; and (vi) reasonable management fees. If Landlord, in its reasonable
discretion, installs a new or replacement capital item for the purpose of
reducing or conserving the use of energy in the Building, complying with any
building code or other law, regulation, or legal requirement, complying with
requirements of any insurer, or improvements (and not repairs or replacements)
otherwise relating to the operation of the Building, the cost of such item
amortized over a reasonable period with interest shall be included in Landlord's
Operating Expenses. Landlord's Operating Expenses shall not include any costs or
expenses incurred by Landlord in the construction and development of the
Building including construction for tenants for which Landlord is entitled to
reimbursement; payments of principal, interest or other charges on mortgages;
and salaries of executives or principals of Landlord (except as the same may be
reflected in the management fee for the Building or attributable to actual
Building operations).

                  2.6.4 "LANDLORD'S TAXES" - DEFINITION. "Landlord's Taxes"
means all taxes, assessments and similar charges assessed or imposed on the Land
for the







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then current calendar year by any governmental authority attributable to the
Building (including personal property associated therewith). The amount of any
special taxes, special assessments and agreed or governmentally imposed "in lieu
of tax" or similar charges shall be included in Landlord's Taxes for any year
but shall be limited to the amount of the installment (plus any interest, other
than penalty interest, payable thereon) of such special tax, special assessment
or such charge required to be paid during or with respect to the year in
question. Landlord's Taxes include expenses, including fees of attorneys,
appraisers and other consultants, incurred in connection with any efforts to
obtain abatements or reduction or to assure maintenance of Landlord's Taxes for
any year wholly or partially included in the Term, whether or not successful and
whether or not such efforts involved filing of actual abatement applications or
initiation of formal proceedings. Landlord's Taxes exclude income taxes of
general application and all estate, succession, inheritance and transfer taxes.
If at any time during the Term there shall be assessed on Landlord, in addition
to or in lieu of the whole or any part of the ad valorem tax on real or personal
property, a capital levy or other tax on the gross rents or other measures of
building operations, or a governmental income, franchise, excise or similar tax,
assessment, levy, charge or fee measured by or based, in whole or in part, upon
Building valuation, gross rents or other measures of building operations or
benefits of governmental services furnished to the Building, then any and all of
such taxes, assessments, levies, charges and fees, to the extent so measured or
based, shall be included within the term Landlord's Taxes, but only to the
extent that the same would be payable if the Building and Land were the only
property of Landlord.

         2.7      ELECTRICITY

         Landlord shall furnish to Tenant throughout the Term electricity for
the operation of lighting fixtures, and 120 volt current for the operation of
normal office fixtures and equipment, but excluding any high energy consumption
equipment. Tenant covenants and agrees to pay, as an additional charge, the cost
of such electricity, which shall be separately metered and billed to Tenant
monthly.


                                   ARTICLE III

                            CONSTRUCTION OF PREMISES

3.1      COMPLETION DATE

         Subject to delay by causes beyond the reasonable control of Landlord or
caused by action or inaction of Tenant, Landlord shall endeavor, in good faith,
to have the Premises ready for Tenant's occupancy as expeditiously as
practicable. So long as Landlord uses commercially reasonable efforts to
complete construction, delays in readying the Premises for Tenant's occupancy,
for any reason, shall not give rise to any








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liability of Landlord hereunder, shall not constitute a Landlord's default,
shall not affect the validity of this Lease, and shall have no effect on the
beginning or end of the Term as otherwise determined hereunder or on Tenant's
obligations associated therewith.

         3.2      WHEN PREMISES DEEMED READY

         The Premises shall be conclusively deemed ready for Tenant's occupancy
as soon as the obligations of Landlord as hereinafter specified have been
substantially completed by Landlord insofar as is practicable in view of delays
or defaults, if any, of Tenant or its contractors, and a certificate of
occupancy is issued for the Premises. Notwithstanding the previous sentence, the
Premises shall be deemed to be ready for Tenant's occupancy if only minor or
insubstantial details of construction, decoration or mechanical adjustments
remain to be done in the Premises or any part thereof, or if the delay in the
availability of the Premises for occupancy is (i) due to special work, changes,
alterations or additions required or made by Tenant in the layout or finish of
the Premises or any part thereof, (ii) caused in whole or in part by Tenant
through the delay of Tenant in submitting any plans and/or specifications,
supplying information, approving plans, specifications or estimates, giving
authorizations or otherwise or (iii) caused in whole or in part by delay and/or
default on the part of Tenant or its contractors. If the Premises are deemed
ready for Tenant's occupancy, but through no fault of Landlord are not in fact
actually ready for Tenant's occupancy, Tenant shall not (except with Landlord's
consent) be entitled to take possession of the Premises for the conduct of its
business until the Premises are in fact actually ready for such occupancy,
notwithstanding the fact, because the Premises shall have as above stated been
deemed ready for such occupancy, that the Term hereof shall on that account have
commenced. Landlord's architect's certificate of substantial completion, or of
any other facts pertinent to this Section 3.2, shall be deemed conclusive of the
statements therein contained and binding upon Tenant. Any of Landlord's work in
the Premises not fully completed on the Term Commencement Date shall thereafter
be so completed with reasonable diligence by Landlord.

         3.3      PLANS AND SPECIFICATIONS

         Landlord shall prepare architectural, electrical and mechanical
construction drawings, plans and specifications (called "Plans") necessary to
lay out the Premises for Tenant's occupancy, at Landlord's sole cost, which
Plans shall be subject to approval by Tenant (which approval shall not be
unreasonably withheld or delayed). Tenant shall promptly provide all information
to the architect necessary for the preparation of the Plans. (The word
"architect" as used in this Section shall include an interior space designer or
planner.)





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         3.4      CONSTRUCTION OF PREMISES

         Except as is otherwise herein provided or as may be otherwise approved
by the Landlord, all work necessary to prepare the Premises for Tenant's
occupancy, including any work to be performed at Tenant's expense, shall be
performed substantially in accordance with the Plans by contractors employed by
Landlord.

         3.5      QUALITY AND COST OF MATERIALS

         Landlord shall bear costs up to $30,825 for materials and workmanship
to be furnished and installed by Landlord pursuant to the Plans. Tenant shall
bear all other costs of preparing the Premises for its occupancy in accordance
with the Plans and shall pay such costs to Landlord upon request as an
additional charge hereunder.

         3.6      TENANT'S DELAY - ADDITIONAL COSTS

         If Tenant fails or omits to make timely submission to Landlord of any
pertinent information, or delays in supplying information, or in approving
plans, specifications or estimates, or in giving authorizations or otherwise,
any additional cost to Landlord in connection with the completion of the
Premises in accordance with the terms of this Lease shall be promptly paid by
Tenant to Landlord, as an additional charge, if such additional cost is the
result of such failure, omission or delay of Tenant. For the purposes of the
preceding sentence, the expression "additional cost to Landlord" shall mean the
cost over and above such cost as would have been the aggregate cost to Landlord
of completing the Premises in accordance with the terms of this Lease had there
been no such failure, omission or delay. Nothing contained in this Section 3.6
shall limit or qualify or prejudice any other covenants, agreements, terms
provisions and conditions contained in this Lease, including, but not limited to
Section 3.2.

         3.7      ENTRY BY TENANT PRIOR TO TERM COMMENCEMENT DATE

         With Landlord's prior written consent, Tenant shall have the right to
enter the Premises prior to the Term Commencement Date, without payment of rent,
to perform such work or decoration as is to be performed by, or under the
direction or control of, Tenant. Such right of entry shall be deemed a license
from Landlord to Tenant, and entry thereunder shall be at the risk of Tenant.

         3.8      CONCLUSIVENESS OF LANDLORD'S PERFORMANCE

         By taking possession of the Premises, Tenant accepts the improvements
in the condition in which they may then be, and waives any right or claim
against Landlord arising out of the condition of the Premises, including the
improvements thereon, the









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appurtenances thereto, and the equipment thereof, except defects in workmanship
and/or materials. Tenant shall be deemed to have waived any right or claim
against Landlord arising out of a defect in workmanship and/or materials on the
date one (1) year following the date on which the Premises were ready for
Tenant's occupancy if Tenant has not then given written notice of such defect to
Landlord.

                                    ARTICLE IV

                              LANDLORD'S COVENANTS

         4.1 BUILDING SERVICES

         Landlord shall furnish services, utilities, facilities and supplies set
forth in this Section 4.1.1 and in Exhibit C. Exhibit C is intended to add
detail to the provisions of the main body of the Lease, and in case of conflict,
the provisions of the main body of the Lease shall control. Tenant may obtain
additional services, utilities, facilities and supplies from time to time upon
reasonable advance request or Landlord may furnish the same without request if
Landlord determines that Tenant's use or occupancy of the Premises necessitates
the same (for example where the condition of the Premises necessitates
additional cleaning services), and, in either case, the cost of the same at
reasonable rates from time to time established by Landlord shall constitute
additional charges, payable within fifteen (15) days after billing.

                  4.1.1 WATER CHARGES. Landlord shall furnish hot and cold water
for ordinary office cleaning, toilet, lavatory and drinking purposes. If Tenant
requires, uses or consumes water for any other purpose, Landlord may assess on
Tenant reasonable charges for additional water.

                  4.1.2 ELEVATOR SERVICE. Landlord shall provide necessary
elevator facilities on Mondays through Fridays excepting legal holidays from
8:00 a.m. to 6:00 p.m. and on Saturdays from 8:00 a.m. to 1:00 p.m. (such hours
on such days being referred to as "business days") and have at least one
elevator serving the Premises in operation available for Tenant's non-exclusive
use at all other times.

                  4.1.3 CLEANING. Landlord shall cause the common areas and the
office areas of the Premises to be kept reasonably clean provided the same are
maintained and kept in good order by Tenant. Cleaning standards shall be in
accordance with Exhibit C.

                  4.1.4 HEAT AND AIR-CONDITIONING. Landlord shall, through the
Building heating and air-conditioning system, furnish to and distribute in the
Premises heat during the normal heating season on business days and
air-conditioning on business days when air-conditioning may reasonably be
required for the comfortable occupancy







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of the Premises by Tenant. Landlord shall not be required to furnish heat and
air-conditioning in the Premises in excess of the capacity of the equipment
presently installed in the Building. If Tenant requests Landlord to provide heat
or air-conditioning after 6:00 p.m. on any business day, after 12:00 noon on
Saturday, on Sunday or on a legal holiday, Tenant shall pay Landlord therefor at
rates reasonably established by Landlord from time to time. If Tenant requires
additional air-conditioning for business machines, meeting rooms or other
purposes, or because of occupancy or unusual electrical loads, any additional
air-conditioning units, chillers, condensers, compressors, ducts, piping and
other equipment and facilities will be installed and maintained by Landlord at
Tenant's sole cost, but only to the extent that the same are compatible with the
Building and its mechanical systems.

                  4.1.5 ENERGY CONSERVATION. Tenant agrees to cooperate with
Landlord and to abide by all Building regulations which Landlord may, from time
to time, prescribe for the proper functioning and protection of the heating and
air-conditioning systems and in order to maximize the effect thereof and to
conserve heat and air-conditioning. Notwithstanding anything to the contrary in
this Section 4.1.1 or otherwise in this Lease, Landlord may institute such
policies, programs and measures as may be in Landlord's judgment necessary,
required or expedient for the conservation or preservation of energy or energy
services, or as may be necessary to comply with applicable codes, rules,
regulations or standards.

         4.2      REPAIRS.

         Except as otherwise provided in this Lease, and except for repairs to
items referred to below necessitated by Tenant's act or neglect (which shall be
Tenant's repair obligation under Section 5.1), Landlord shall make such repairs
to the roofs, exterior walls, exterior windows, floor slabs, core walls, and
common areas and facilities in the Building as may be necessary to keep them in
good condition.

         4.3      QUIET ENJOYMENT.

         Landlord covenants that Tenant, on paying the rent and performing the
Tenant obligations in this Lease, shall peacefully and quietly have, hold and
enjoy the Premises, free from any claim by Landlord or persons claiming under
Landlord, but subject to all of the terms and provisions hereof, provisions of
law and rights of record to which this Lease is or may become subordinate. This
covenant is in lieu of any other so-called quiet enjoyment covenant, either
express or implied.

         4.4      INTERRUPTION

         Landlord shall not be liable to Tenant for any compensation or
reduction of rent by reason of inconvenience or annoyance or for loss of
business arising from the








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necessity of Landlord or its agents entering the Premises for any of the
purposes authorized in this Lease or for repairing the Premises or from repairs
by Landlord of any portion of the Building however the necessity may occur. In
case Landlord is prevented or delayed from diligent construction of
improvements, making any repairs, alterations or improvements, or furnishing any
services or performing any other covenant or duty to be performed on Landlord's
part, by reason of any cause reasonably beyond Landlord's control, Landlord
shall not be liable to Tenant therefor, nor, except as otherwise provided in
Section 6.1, shall Tenant be entitled to any abatement or reduction of rent by
reason thereof, nor shall the same give rise to a claim in Tenant's favor that
such failure constitutes actual or constructive, total or partial, eviction from
the Premises. Notwithstanding the previous sentence, if Tenant is prevented, on
account of Landlord's failure to provide an essential service required under the
Lease where such failure is caused by matters within Landlord's reasonable
control, from using all or a substantial portion of the Premises for more than
ten (10) business days following notice to Landlord, then from and after the end
of such ten (10) business day period until such essential service is restored,
Annual Fixed Rent or a just and proportionate part thereof, shall be abated. In
no event shall Landlord be liable for indirect or consequential damages arising
out of any default by Landlord.

         Landlord reserves the right to stop any service or utility system, when
necessary by reason of accident or emergency, or until necessary repairs have
been completed; provided, however, that in each instance of stoppage, Landlord
shall exercise reasonable diligence to eliminate the cause thereof. Except in
case of emergency repairs, Landlord will give Tenant reasonable advance notice
of any contemplated stoppage and will use reasonable efforts to avoid
unnecessary interruption of Tenant's use of the Premises by reason thereof.


                                    ARTICLE V

                          TENANT'S ADDITIONAL COVENANTS

         5.1      MAINTENANCE AND REPAIR

         Except for damage by fire or casualty and reasonable wear, Tenant shall
at all times keep the Premises clean, neat and in as good repair, order and
condition as the same are at the beginning of the Term or may be put in
thereafter. The foregoing shall include without limitation Tenant's obligation
to maintain floors and floor coverings, to paint and repair walls and doors, to
replace and repair ceiling tiles, lights and light fixtures, drains and the
like, and clean the Premises to the extent such cleaning is not to be performed
by Landlord under Exhibit C.

         5.2      USE, WASTE AND NUISANCE





                                       13
<PAGE>   15


         Throughout the Term, Tenant shall occupy the Premises for the Permitted
Uses only, and shall not use the Premises for any other purpose. Tenant shall
not injure, overload, deface or commit waste in the Premises or any part of the
improvement on the Land, nor permit the emission therefrom of any objectionable
noise, light or odor, nor use or permit any use of the Premises which is
improper, offensive, contrary to law or ordinance or which is liable to
invalidate or increase the premium for any insurance on the Building or its
contents or which is liable to render necessary any alterations or additions in
the Building, nor obstruct in any manner any portion of the Building. If
Tenant's use of the Premises results in an increase in the premium for any
insurance on the Building or the contents thereof, Landlord shall notify Tenant
of such increase and Tenant shall pay same as additional charges. Tenant may not
without Landlord's consent install in the Premises any pay telephones, vending
machines, water fountains, refrigerators, sinks or cooking equipment provided
that Landlord's consent will not be unreasonably withheld with respect to items
designed for the convenience of Tenant's employees which are customary for
office employees if Landlord determines that special venting or other matters
are not required in connection therewith.

         Tenant shall not (either with or without negligence) cause or permit
the escape, disposal or release of any biologically or chemically active or
other hazardous substances, or materials. Tenant shall not allow the storage or
use of such substances or materials in any manner not sanctioned by law or by
the highest standards prevailing in the industry for the storage and use of such
substances or materials, nor allow to be brought into the Building any such
materials or substances except to use in the ordinary course of Tenant's
business, and then only after written notice is given to Landlord of the
identity of such substances or materials. Without limitation, hazardous
substances and materials shall include those described in the Comprehensive
Environmental Response, Compensation and Liability Act of 1980, as amended, 42
U.S.C. ss.9601 et seq., the Resource Conservation and Recovery Act, as amended,
42 U.S.C. ss.6901 et seq., the Massachusetts Hazardous Waste Management Act, as
amended, M.G.L. Chapter 21C, and the Massachusetts Oil and Hazardous Material
Release Prevention Act, as amended, M.G.L. Chapter 21E, and the regulations
adopted under these acts. If any lender or governmental agency shall ever
require testing to ascertain whether or not there has been any release of
hazardous materials, then the reasonable costs thereof shall be reimbursed by
Tenant to Landlord upon demand as additional charges if such requirement applies
to the Premises, and if the requirement applies to the Building generally, then
such costs shall be included in Landlord's Operating Expenses. In addition,
Tenant shall execute affidavits, representations and the like from time to time
at Landlord's request concerning Tenant's best knowledge and belief regarding
the presence of hazardous substances or materials on the Premises. In all
events, Tenant shall indemnify Landlord in the manner elsewhere provided from
any release of hazardous materials on the Premises occurring while Tenant is in
possession, or elsewhere if caused by Tenant or persons acting under Tenant.




                                       14
<PAGE>   16

         5.3      RULES AND REGULATIONS

         Tenant shall conform to all reasonable non-discriminatory rules and
regulations now or hereafter promulgated by Landlord for the care and use of the
Premises and the Building.

         5.4      SAFETY APPLIANCES

         Tenant shall keep the Premises equipped with all safety appliances and
permits which, as a result of Tenant's particular activities, are required by
law or ordinance or any order or regulation of any public authority, shall keep
the Premises equipped at all times with adequate fire extinguishers and other
such equipment reasonably required by Landlord, and, subject to Section 5.10,
shall make all repairs, alterations, replacements, or additions so required as a
result of Tenant's particular activities.

         5.5      INDEMNIFICATION AND INSURANCE

         Tenant shall save Landlord, its mortgagees, agents, employees,
independent contractors, invitees, and any other parties designated by Landlord
from time to time (collectively, the "Indemnitees") harmless and indemnified
(and shall defend the Indemnitees with counsel reasonably approved by the
Indemnitees) against any claim, loss or cost arising in whole or in part out of
any injury, loss, theft or damage to any person or property while on or in the
Premises, or in transit thereto or therefrom, or out of any condition within or
around the Premises, to the extent not due to negligence or willful misconduct
of the Indemnitees, and to any person or property anywhere occasioned by any
act, omission, neglect or default of Tenant or of employees, agents, independent
contractors or invitees of Tenant or any person acting under Tenant. In addition
to the foregoing, Landlord may make all repairs and replacements to the
improvements on the Land resulting from acts or omissions of Tenant's employees,
agents, independent contractors or invitees or any other persons acting under
Tenant (including damage and breakage occurring as a result of work performed by
or for Tenant and when Tenant's property is being moved into or out of the
Building) and Landlord may recover all costs and expenses thereof from Tenant as
additional charges. Throughout the Term (and such further time as Tenant or any
person claiming through Tenant occupies any part of the Premises) Tenant shall
maintain in a responsible company or companies approved by Landlord, liability
insurance in form satisfactory to Landlord, written on an occurrence basis,
insuring the Indemnitees and other parties designated by Landlord, and Tenant,
as their respective interests may appear, against all claims, demands or actions
for injury, death, and property damage in amounts not less than those specified
in Section 1.1 (as such amounts may, from time to time, be reasonably increased
by Landlord). All insurance to be maintained by Tenant under this Section 5.5
shall provide that it will not be subject to cancellation, termination, or






                                       15
<PAGE>   17
 change except after at least 30 days' prior written notice to the Indemnitees
and other parties designated by Landlord. The policy or policies or a duly
executed certificate or certificates for the same (together with satisfactory
evidence of the payment of the premium thereon if requested by Landlord) shall
be deposited with Landlord and other parties designated by Landlord at the
beginning of the Term and, upon renewals of such policies, not less than 30 days
prior to the expiration of the term of such coverage. If Tenant fails to comply
with any of the foregoing requirements, Landlord may obtain such insurance on
behalf of Tenant and may keep the same in effect, and Tenant shall pay Landlord,
as additional charges, the premium cost thereof upon demand. The covenants of
this Section 5.5 shall survive the expiration of the Term or earlier termination
of this Lease.

         5.6      TENANT'S PROPERTY

         All furnishings, fixtures, equipment, effects and property of Tenant
and of all persons claiming through Tenant which from time to time may be on the
Premises or elsewhere in the Building or in transit thereto or therefrom shall
be at the sole risk of Tenant and shall be kept insured by Tenant throughout the
term at Tenant's expense and in prudent amounts, 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 Landlord unless caused by the negligence or willful misconduct of
Landlord or its agents. The parties acknowledge that damage or destruction may
result from acts of cleaning personnel and employees of other independent
contractors of Landlord working in and around the Premises and that Tenant shall
bear the risk and cost thereof unless Landlord has been negligent in the
selection of such persons.

         5.7      ENTRY FOR REPAIRS AND INSPECTIONS

         Tenant shall permit Landlord and its agents to enter and examine the
Premises at reasonable times and after reasonable notice (except no notice shall
be required in an emergency), if Landlord shall so elect, to make any repairs or
replacements Landlord may deem necessary or desirable, to remove at Tenant's
expense any alterations, additions, signs, curtains, blinds, shades, awnings,
aerials, flagpoles, or the like not consented to in writing, and to show the
Premises to prospective tenants during the twelve (12) months preceding
expiration of the Term and to prospective purchasers and mortgagees at all
times. In case of an emergency in the Premises or in the Building, Landlord or
its representative may enter the Premises (forcibly, if necessary) at any time
to take such measures as may be needed to deal with such emergency.








                                       16
<PAGE>   18

         5.8      ASSIGNMENT, SUBLETTING

         Tenant shall not assign this Lease, or sublet or license the Premises
or any portion thereof, or permit the occupancy of all or any portion of the
Premises by anybody other than Tenant (all or any of the foregoing actions are
referred to as "Subleases" and all or any of assignees, subtenants, licensees,
and other such parties are referred to as "Subtenants") without obtaining, on
each occasion, the prior consent of the Landlord, which consent shall not be
required for a Related Party Transfer. "Related Party Transfer" shall include
any assignment, sublet, license or any other transfer by Tenant to a successor
by merger, any party acquiring all or substantially all of Tenant's stocks and
assets, or any affiliate. Affiliate shall mean any entity controlled by Tenant
or controlled by the same persons who control Tenant, where control is
established by demonstrating the possession of 50 percent ownership of the
shares of beneficial interest of the entity in question, together with the power
to control and manage the affairs thereof either directly or by election of
directors and/or officers. Unless Landlord's consent specifically provides
otherwise with respect to a particular proposed Subtenant, Tenant shall not
offer to make or enter into negotiations with respect to a Sublease to any of
the following: (i) a tenant in the Hobbs Brook Office Park; (ii) any party with
whom Landlord or any affiliate of Landlord is then negotiating with respect to
space in the Hobbs Brook Office Park; (iii) any entity owned by, owning, or
affiliated with, directly or indirectly, any tenant or party described in
clauses (i) and (ii) hereof; or (iv) any party which would be of such type,
character or condition as to be inappropriate, in Landlord's judgment, as a
tenant for a first class office building. Tenant shall not, without Landlord's
approval, offer to make or make a Sublease of all or any portion of the Premises
unless the aggregate rent and other charges payable to Tenant under such
Sublease equal or exceed the greater of (i) aggregate rent and other charges
payable hereunder (pro-rated for a Sublease of less than all of the Premises),
or (ii) the then prevailing rent rate being quoted for comparable space in Hobbs
Brook Office Park. Tenant's request for consent to a Sublease shall include a
copy of the proposed Sublease instrument, if available, or else a statement of
the proposed Sublease in detail satisfactory to Landlord, together with
reasonably detailed financial, business and other information about the proposed
Subtenant. Consent may be granted in Landlord's sole discretion, but such
consent or refusal to consent shall not be unreasonably delayed. Landlord shall
have the option (but not the obligation) to terminate the Lease with respect to
the portion of the Premises which Tenant proposes to Sublease effective upon the
date of the proposed Sublease and continuing for the proposed term thereof by
giving Tenant notice of such termination within 60 days after Landlord's receipt
of Tenant's request. If Tenant does make a Sublease hereunder, and if the
aggregate rent and other charges payable to Tenant under and in connection with
such Sublease (including without limitation any amounts paid for leasehold
improvements or on account of Tenant's costs associated with such Sublease)
exceed the rent and other charges paid hereunder with respect to the space in
question, Tenant shall pay to Landlord, as an additional charge, the amount of
such excess. If the amount of rent and other charges payable under a







                                       17
<PAGE>   19

Sublease is not readily ascertainable, such amount may, at Landlord's option, be
deemed to equal the fair market rent then obtainable for the space in question.

         Tenant shall pay to Landlord, as an additional charge, Landlord's
reasonable legal fees and other expenses incurred in connection with any
proposed Sublease, including fees for review of documents and investigations of
proposed Subtenants. Notwithstanding any such Sublease, the original Tenant
named herein shall remain directly and primarily obligated under this Lease.

         If Tenant enters into any Sublease with respect to the Premises (or any
part thereof), Landlord may, at any time and from time to time, require that
such Subtenant agree directly with Landlord to be liable, jointly and severally
with Tenant, to the extent of the obligation undertaken by or attributable to
such Subtenant, for the performance of Tenant's agreements under this Lease
(including payment of rent and other charges under the Sublease), and every
Sublease shall so provide. Landlord may collect rent and other charges from the
Subtenant and apply the net amount collected to the rent and other charges
hereunder, but no such assignment or collection shall be deemed a waiver of the
provisions of Section 5.8, or the acceptance of the Subtenant, as a tenant, or a
release of Tenant from direct and primary liability for the further performance
of Tenant's covenants hereunder. The consent by Landlord to a particular
Sublease shall not relieve Tenant from the requirement of obtaining the consent
of Landlord to any further Sublease.

         5.9      ALTERATIONS

         Tenant shall make no alterations, additions or improvements to the
Premises without the prior written consent of Landlord and only in accordance
with complete construction documents approved in advance by Landlord. All such
alterations, additions and improvements shall be done only by contractors
approved in advance by Landlord. Tenant shall obtain all necessary permits
before undertaking any such alterations, additions or improvements and shall
carry such insurance and obtain such payment, performance and lien bonds as
Landlord shall reasonably require. Any alterations, additions and improvements
to the Premises, except movable furniture and trade fixtures, shall belong to
Landlord. All alterations, additions and improvements to the Premises shall be
at Tenant's sole cost. If any mechanic's lien (which term shall include all
similar liens relating to the furnishing of labor and materials) is filed
against the Building which is claimed to be attributable to Tenant, its agents,
employees or contractors, Tenant shall give immediate notice of such lien to
Landlord and shall discharge the same by payment or filing any necessary bond
within 10 days after Tenant has notice (from any source) of such lien.
Landlord's approval of the construction documents shall signify Landlord's
consent to the work shown thereon only and Tenant shall be solely responsible
for any errors or omissions contained therein.




                                       18
<PAGE>   20

         5.10     SURRENDER

         At the expiration of the Term or earlier termination of this Lease,
without the requirement of any notice, Tenant shall peaceably surrender the
Premises including all alterations and additions thereto and all replacements
thereof, including carpeting, any water or electricity meters, and all fixtures
and partitions, in any way bolted or otherwise attached to the Premises (which
shall become the property of Landlord) except such alterations and additions as
Landlord shall have directed Tenant to remove at the time Tenant requested
Landlord's consent to the installation of the same, the Premises and
improvements to be in the condition in which the same are required to be
maintained under Section 5.1. Tenant shall, at the time of termination, remove
the goods, effects and fixtures which Tenant is directed or permitted to remove
in accordance with the provisions of this Section, making any repairs to the
Premises and other areas necessitated by such removal and leaving the Premises
clean and tenantable. Should Tenant fail to remove any of such goods, effects,
and fixtures, Landlord may have them removed forcibly, if necessary, and store
any of Tenant's property in a public warehouse at the risk of Tenant. If such
items are not removed from storage within thirty (30) days, such items may be
sold by any customary methods in order to pay storage costs and other expenses
of Landlord. The expense of such removal, storage and reasonable repairs
necessitated by such removal shall be borne by Tenant or reimbursed by Tenant to
Landlord.

         5.11     PERSONAL PROPERTY TAXES

         Tenant shall pay promptly when due all taxes (and charges in lieu
thereof) imposed upon Tenant's personal property in the Premises, no matter to
whom assessed (including, without limitation, fixtures and equipment).


                                   ARTICLE VI

                               CASUALTY AND TAKING

         6.1      DAMAGE BY FIRE OR CASUALTY

         If the Premises or any part thereof shall be damaged by fire or other
insured casualty, then, subject to the last paragraph of this Section 6.1,
Landlord shall proceed with diligence, subject to then applicable statutes,
building codes, zoning ordinances and regulations of any governmental authority,
and at the expense of Landlord (but only to the extent of insurance proceeds
made available to Landlord by any mortgagee of the Building) to repair or cause
to be repaired such damage. All such repairs made necessary by any act or
omission of Tenant shall be made at the Tenant's expense to the extent that the
cost of such repairs are less than the commercially reasonable deductible







                                       19
<PAGE>   21

amount in Landlord's insurance policy. All repairs to and replacements of
property which Tenant is entitled to remove shall be made by and at the expense
of Tenant. If the Premises or any part thereof shall have been rendered unfit
for use and occupation hereunder by reason of such damage the Fixed Rent and all
other amounts payable by Tenant hereunder, or a just and proportionate part
thereof, according to the nature and extent to which the Premises shall have
been so rendered unfit, shall be abated until the Premises (except as to the
property which is to be repaired by or at the expense of Tenant) shall have been
restored as nearly as practicable to the condition in which they were
immediately prior to such fire or other casualty. Landlord shall not be liable
for delays in the making of any such repairs which are due to government
regulation, casualties and strikes, unavailability of labor and materials,
delays in obtaining insurance proceeds, and other causes beyond the reasonable
control of Landlord, nor shall Landlord be liable for any inconvenience or
annoyance to Tenant or injury to the business of Tenant resulting from delays in
repairing such damage.

         If (i) the Premises are so damaged by fire or other casualty (whether
or not insured) at any time during the last twelve (12) months of the Term that
the cost to repair such damage is reasonably estimated to exceed one-third of
the total Annual Fixed Rent payable hereunder for the period from the estimated
completion date of repair until the end of the Term, (ii) at any time the
Building (or any portion thereof, whether or not including any portion of the
Premises) is so damaged by fire or other casualty (whether or not insured) that
substantial alteration or reconstruction or demolition of the Building (or a
portion thereof) shall in Landlord's judgment be required, or (iii) at any time
damage to the Building occurs by fire or other insured casualty and any
mortgagee shall refuse to permit insurance proceeds to be utilized for the
repair or replacement of such property and Landlord determines not to repair
such damage, then and in any of such events, this Lease and the term hereof may
be terminated at the election of Landlord by a notice from Landlord to Tenant
within sixty (60) days, or such longer period as is required to complete
arrangements with any mortgagee regarding such situation, following such fire or
other casualty; the effective termination date pursuant to such notice shall be
not less than thirty (30) days after the day on which such termination notice is
received by Tenant. In the event of any termination, the Term shall expire as
though such effective termination date were the date originally stipulated in
Section 1.1 for the end of the Term and the Fixed Rent and additional charges
for Operating Expenses and Taxes shall be apportioned as of such date. If any
portion (other than a portion which, if not repaired, would not unreasonably
affect Tenant's use of the Premises for the Permitted Uses) of the Premises is
damaged by fire or other casualty and Landlord has not within six (6) months of
such casualty substantially completed (subject only to punchlist-type items the
completion of which does not unreasonably interfere with the Tenant's use of the
Premises) repair of such damage, then, within ten (10) days after such six-month
period has expired, Tenant may terminate this Lease by notice to Landlord
effective on the 30th day after such notice is given, provided that such








                                       20
<PAGE>   22

termination notice shall be effective only if repair of the damage in question
has not been substantially completed before the date of termination.

         6.2      CONDEMNATION - EMINENT DOMAIN

         In case during the Term all or any substantial part of the Premises or
the Building are taken by eminent domain or Landlord receives compensable damage
by reason of anything lawfully done in pursuance of public or other authority,
this Lease shall terminate at Landlord's election, which may be made
(notwithstanding that Landlord's entire interest may have been divested) by
notice given to Tenant within 90 days after the election to terminate arises,
specifying the effective date of termination. The effective date of termination
specified by Landlord shall not be less than 15 nor more than 30 days after the
date of notice of such termination. If any portion (other than a portion which,
if condemned, would not unreasonably affect Tenant's use of the Premises for the
Permitted Uses) of the Premises is taken by eminent domain and thereby rendering
the Premises unfit for use and occupation, Tenant may terminate this Lease by
notice to Landlord effective on the 30th day after such notice is given. Unless
terminated pursuant to the foregoing provisions, this Lease shall remain in full
force and effect following any such taking, subject, however, to the following
provisions. If in any such case the Premises are rendered unfit for use and
occupation and this Lease is not terminated, Landlord shall use due diligence
(following the expiration of the period in which Landlord may terminate this
Lease pursuant to the foregoing provisions of this Section) to put the Premises,
or what may remain thereof (excluding any items installed or paid for by Tenant
which Tenant may be required to remove pursuant to Section 5.12), into proper
condition for use and occupation and a just proportion of the Fixed Rent and
additional charges for Operating Expenses and Taxes according to the nature and
extent of the injury shall be abated until the Premises or such remainder shall
have been put by Landlord in such condition; and in case of a taking which
permanently reduces the area of the Premises, a just proportion of the Fixed
Rent and additional charges for Operating Expenses and Taxes shall be abated for
the remainder of the Term.







                                       21
<PAGE>   23

         6.3      EMINENT DOMAIN AWARD

         Except for Tenant's relocation expenses (specifically so designated by
the court or authority having jurisdiction over the matter) Landlord reserves to
itself any and all rights to receive awards made for damages to the Premises,
the Building or the leasehold hereby created, or any one or more of them,
accruing by reason of exercise of eminent domain or by reason of anything
lawfully done in pursuance of public or other authority. Tenant hereby releases
and assigns to Landlord all Tenant's rights to such awards, and covenants to
deliver such further assignments and assurances thereof as Landlord may from
time to time request, hereby irrevocably designating and appointing Landlord as
its attorney-in-fact to execute and deliver in Tenant's name and behalf all such
further assignments thereof.


                                  ARTICLE VII

                                     DEFAULT

         7.1      TERMINATION FOR DEFAULT OR INSOLVENCY

         This Lease is upon the condition that (1) if Tenant shall fail to
perform or observe any of Tenant's covenants, and if such failure shall
continue, (a) in the case of rent or payment of additional charges or any sum
due Landlord hereunder, for more than ten (10) days, or (b) in any other case,
after notice, for more than thirty (30) days (provided that if correction of any
such matter reasonably requires longer than 30 days and Tenant so notifies
Landlord within 20 days after Landlord's notice is given together with an
estimate of time required for such cure, Tenant shall be allowed such longer
period, but only if cure is begun within such 30-day period and such delay does
not cause increased risk of damage to person or property), or (2) if three or
more notices under clause (1) hereof are given in any twelve month period
(failure to pay rent or any other sum for more than 3 days after the particular
due date shall have the same effect under this clause (2) as such a notice); (3)
if Tenant shall vacate more than 50 percent of the Rentable Floor Area of
Premises; (4) if the leasehold hereby created shall be taken on execution, or by
other process of law, or if any assignment shall be made of Tenant's property or
the property of any guarantor of Tenant's obligations hereunder ("Guarantor")
for the benefit of creditors; or (5) if a receiver, guardian, conservator,
trustee in bankruptcy or similar officer shall be appointed by a court of
competent jurisdiction to take charge of all or any part of Tenant's or the
Guarantor's property and such appointment is not discharged within 90 days
thereafter or if a petition including, without limitation, a petition for
reorganization or arrangement is filed by Tenant or the Guarantor under any
bankruptcy law or is filed against Tenant or the Guarantor and, in the case of a
filing against Tenant only, the same shall not be dismissed within 90 days from
the date upon which it is filed, then, and in any of said cases, Landlord may,








                                       22
<PAGE>   24

immediately or at any time thereafter, elect to terminate this Lease by notice
of termination, by entry, or by any other means available under law and may
recover possession of the Premises as provided herein. Upon termination by
notice, by entry, or by any other means available under law, Landlord shall be
entitled immediately, in the case of termination by notice or entry, and
otherwise in accordance with the provisions of law to recover possession of the
Premises from Tenant and those claiming through or under the Tenant. Such
termination of this Lease and repossession of the Premises shall be without
prejudice to any remedies which Landlord might otherwise have for arrears of
rent or for a prior breach of the provisions of this Lease. Tenant waives any
statutory notice to quit and equitable rights in the nature of further cure or
redemption, and Tenant agrees that upon Landlord's termination of this Lease
Landlord shall be entitled to re-entry and possession in accordance with the
terms hereof. Landlord may, without notice, store Tenant's personal property
(and those of any person claiming under Tenant) at the expense and risk of
Tenant or, if Landlord so elects, Landlord may sell such personal property at
public auction or auctions or at private sale or sales after seven days notice
to Tenant and apply the net proceeds to the earliest of installments of rent or
other charges owing Landlord. Tenant agrees that a notice by Landlord alleging
any default shall, at Landlord's option (the exercise of such option shall be
indicated by the inclusion of the words "notice to quit" in such notice),
constitute a statutory notice to quit. If Landlord exercises its option to
designate a notice of default hereunder as a statutory notice to quit, any grace
periods provided for herein shall run concurrently with any statutory notice
periods. Landlord and Tenant waive trial by jury in any action to which they are
parties. Tenant further agrees that it shall not interpose any counterclaim or
set-off in any summary proceeding or in any action based in whole or in part on
non-payment of rent.

         7.2      REIMBURSEMENT OF LANDLORD'S EXPENSES

         In the case of termination of this Lease pursuant to Section 7.1,
Tenant shall reimburse Landlord for all reasonable expenses arising out of such
termination, including without limitation, all reasonable costs incurred in
collecting amounts due from Tenant under this Lease (including attorneys' fees,
costs of litigation and the like); all reasonable expenses incurred by Landlord
in attempting to relet the Premises or parts thereof (including advertisements,
brokerage commissions, Tenant's allowances, costs of preparing space, and the
like); all of Landlord's then unamortized costs of special inducements provided
to Tenant (including without limitation rent holidays, rent waivers, above
building standard leasehold improvements, and the like) and all Landlord's other
reasonable expenditures necessitated by the termination. The reimbursement from
Tenant shall be due and payable immediately from time to time upon notice from
Landlord that an expense has been incurred, without regard to whether the
expense was incurred before or after the termination.

         7.3      DAMAGES





                                       23
<PAGE>   25


         Landlord may elect by written notice to Tenant within one year
following such termination to be indemnified for loss of rent by a lump sum
payment representing the then present value of the amount of rent and additional
charges which would have been paid in accordance with this Lease for the
remainder of the Term minus the then present value of the aggregate fair market
rent and additional charges payable for the Premises for the remainder of the
Term (if less than the rent and additional charges payable hereunder), estimated
as of the date of the termination, and taking into account reasonable
projections of vacancy and time required to re-lease the Premises. (For the
purposes of calculating the rent which would have been paid hereunder for the
lump sum payment calculation described herein, the last full year's additional
charges under Section 2.6 is to be deemed constant for each year thereafter. The
Federal Reserve discount rate (or equivalent) shall be used in calculating
present values.) Should the parties be unable to agree on a fair market rent,
the matter shall be submitted, upon the demand of either party, to the Boston,
Massachusetts office of the American Arbitration Association, with a request for
arbitration in accordance with the rules of the Association by a single
arbitrator who shall be an MAI appraiser with at least ten years experience as
an appraiser of major office buildings in the Greater Boston area. The parties
agree that a decision of the arbitrator shall be conclusive and binding upon
them. If, at the end of the Term, the rent which Landlord has actually received
from the Premises is less than the aggregate fair market rent estimated as
aforesaid, Tenant shall thereupon pay Landlord the amount of such difference.
Should Landlord fail to make the election provided for in this Section 7.3,
Tenant shall indemnify Landlord for the loss of rent by a payment at the end of
each month which would have been included in the Term, representing the
difference between the rent which would have been paid in accordance with this
Lease (Annual Fixed Rent under Section 2.5, and additional charges which would
have been payable under Section 2.6 to be ascertained monthly) and the rent
actually derived from the Premises by Landlord for such month (the amount of
rent deemed derived shall be the actual amount less any portion thereof
attributable to Landlord's reletting expenses described in Section 7.2 which
have not been reimbursed by Tenant thereunder).

         7.4      MITIGATION

         Any obligation imposed by law upon Landlord to relet the Premises shall
be subject to the reasonable requirements of Landlord to lease to high quality
tenants and to develop the Building in a harmonious manner with an appropriate
mix of uses, tenants, floor areas and terms of tenancies, and the like.

         7.5      CLAIMS IN BANKRUPTCY

         Nothing herein shall limit or prejudice the right of Landlord to prove
and obtain in a proceeding for bankruptcy, insolvency, arrangement or
reorganization, by reason of






                                       24
<PAGE>   26

the termination, an amount equal to the maximum allowed by a statute or law in
effect at the time when, and governing the proceedings in which, the damages are
to be proved, whether or not the amount is greater to, equal to, or less than
the amount of the loss or damage which Landlord has suffered.

         7.6      INTEREST ON UNPAID AMOUNTS

         If any payment of Annual Fixed Rent, additional charges, or other
payment due from Tenant to Landlord is not paid when due, then without notice
and in addition to all other remedies hereunder, Tenant shall pay to Landlord
interest on such unpaid amount equal to 1.25% of the amount in question for each
month and for each part thereof during which said delinquency continues;
provided, however, in no event shall such interest exceed the maximum amount
permitted to be charged by applicable law.

         7.7      VACANCY DURING LAST SIX MONTHS

         If Tenant vacates all of the Premises within the last 6 months of the
Term, Landlord may enter the Premises and commence demolition work or
construction of leasehold improvements for future tenants. The exercise of such
right by Landlord will not affect Tenant's obligations to pay Annual Fixed Rent
or additional charges with respect to the Premises, which obligations shall
continue without abatement until the end of the Term.


                                  ARTICLE VIII

                                  MISCELLANEOUS

         8.1      HOLDOVER

         If Tenant remains in the Premises after the termination or expiration
of the Term, such holding over shall be as a tenant at will or tenant by the
month (requiring 30 days notice of termination by either party to the other) at
a monthly fixed rent equal to twotimes the Fixed Rent due hereunder for the last
month of the Term, and otherwise subject to all the covenants and conditions
(including obligations to pay additional charges under Section 2.6) of this
Lease as though it had originally been a monthly tenancy. Notwithstanding the
foregoing, if Landlord desires to regain possession of the Premises promptly
after the termination or expiration hereof and prior to acceptance of rent for
any period thereafter, Landlord may, at its option, forthwith re-enter and take
possession of the Premises or any part thereof by any legal process in force in
The Commonwealth of Massachusetts.





                                       25
<PAGE>   27

         Notwithstanding the establishment of any holdover tenancy following the
expiration or earlier termination of the Term, if Tenant fails promptly to
vacate the Premises at the expiration or earlier termination of the Term, Tenant
shall save Landlord harmless and indemnified against any claim, loss, cost or
expense (including reasonable attorneys' fees) arising out of Tenant's failure
promptly to vacate the Premises (or any portion thereof).

         8.2      ESTOPPEL CERTIFICATES

         At Landlord's request, from time to time, Tenant agrees to execute and
deliver to Landlord, within ten (10) days after such request, a certificate
which acknowledges the dates on which the Term begins and ends, tenancy and
possession of the Premises and recites such other facts concerning any provision
of the Lease or payments made under the Lease which Landlord or a mortgagee or
lender or a purchaser or prospective purchaser of the Building or any interest
therein or any other party may from time to time reasonably request. Tenant
acknowledges that the execution and delivery of such certificates in connection
with a financing or sale in a prompt manner constitute requirements of
Landlord's financing and/or property dispositions. Without limitation of the
foregoing, Tenant agrees to execute a document in the form of Exhibit D, or
whatever other instruments may reasonably be required by the first mortgagee or
junior mortgagee to acknowledge such tenancy in a recordable form, within ten
(10) days after Landlord's request, correcting as appropriate any
representations which are not then correct.

         8.3      NOTICE

         Any notice, approval, consent and other like communication hereunder
from Landlord to Tenant or from Tenant to Landlord shall be effective only if
given in writing and shall be deemed duly served if and when hand delivered or
if and when mailed prepaid certified mail (in either case, whether or not
accepted for delivery). Communications to Tenant shall be addressed to Tenant's
Authorized Representative at the Original Address of Tenant set forth in Section
1.1 prior to the Term Commencement Date and thereafter at the Premises.
Communications to Landlord shall be addressed to the Address of Landlord set
forth in Section 1.1. Either party may from time to time designate other
addresses within the continental United States by notice to the other.

         8.4      LANDLORD'S RIGHT TO CURE

         At any time and without notice, Landlord may, but need not, cure any
failure by Tenant to perform its obligations under this Lease. Whenever Landlord
chooses to do so, Tenant shall pay all costs and expenses incurred by Landlord
in curing any such failure, including, without limitation, reasonable attorneys'
fees together with an








                                       26
<PAGE>   28
administrative charge equal to 15% of such costs and expenses (or such higher
percentage as may then be customary with respect to first-class office buildings
in the Greater Boston area) and interest as provided in Section 7.6.

         8.5      SUCCESSORS AND ASSIGNS

         This Lease and the covenants and conditions herein contained shall
inure to the benefit of and be binding upon Landlord, its successors and
assigns, and shall be binding upon Tenant, its successors and assigns, and shall
inure to the benefit of Tenant and only such Subtenants of Tenant as are
permitted hereunder. The term "Landlord" means the original Landlord named
herein, its successors and assigns. The term "Tenant" means the original Tenant
named herein and its permitted successors and assigns.

         8.6      BROKERAGE

         Landlord and Tenant each warrant that it has had no dealings with any
broker or agent in connection with this Lease or any other space in the Hobbs
Brook Office Park except for any brokers designated in Section 1.1. Each
covenants to pay, hold harmless and indemnify the other from and against any and
all costs, expense or liability for any compensation, commissions and charges
claimed by any broker or agent other than any such broker designated in Section
1.1 with respect to this Lease or the negotiation thereof arising from a breach
of the foregoing warranty. Landlord shall be responsible for payment of any
brokerage commission to any broker designated in Section 1.1.

         8.7      WAIVER

The failure of Landlord or of Tenant to seek redress for violation of, or to
insist upon strict performance of, any covenant or condition of this Lease, or,
with respect to such failure of Landlord, any of the Rules and Regulations
referred to in Section 5.3, whether heretofore or hereafter adopted by Landlord,
shall not be deemed a waiver of such violation nor prevent a subsequent act,
which would have originally constituted a violation, from having all the effect
of an original violation, nor shall the failure of Landlord to enforce any of
said Rules and Regulations against any other tenant of the Building be deemed a
waiver of any such Rules or Regulations. The receipt by Landlord of Fixed Rent
or additional charges with knowledge of the breach of any covenant of this Lease
shall not be deemed waiver of such breach. No provision of this Lease shall be
deemed to have been waived by Landlord, or by Tenant, unless such waiver be in
writing signed by the party to be charged. 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.

         8.8      ACCORD AND SATISFACTION






                                       27
<PAGE>   29


         No acceptance by Landlord of a lesser sum than the Fixed Rent and
additional charges then due shall be deemed to be other than on account of the
earliest installment of such rent and charges 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 Landlord may accept such check or
payment without prejudice to Landlord's right to recover the balance of such
installment or pursue any other remedy provided in this Lease. The delivery of
keys to Landlord shall not operate as a termination of this Lease or a surrender
of the Premises.

         8.9      REMEDIES CUMULATIVE

         The specific remedies to which Landlord may resort under the terms of
this Lease are cumulative and are not intended to be exclusive of any other
remedies to which it may be lawfully entitled in case of any breach or
threatened breach by Tenant of any provisions of this Lease. In addition to the
other remedies provided in this Lease, Landlord shall be entitled to the
restraint by injunction of the violation or attempted or threatened violation of
any of the covenants or conditions of this Lease or to a decree compelling
specific performance of any such covenants or conditions.

         8.10     PARTIAL INVALIDITY

         If any term of this Lease, or the application thereof to any person or
circumstance, 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.

         8.11     WAIVERS OF SUBROGATION

         Any insurance carried by either party with respect to the Premises or
property therein or occurrences thereon shall, if it can be so written without
additional premium or with an additional premium which the other party agrees to
pay, include a clause or endorsement denying to the insurer rights of
subrogation against the other party to the extent rights have been waived by the
insured hereunder 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 due to hazards covered
by such insurance to the extent of the indemnification received thereunder.

         8.12     ENTIRE AGREEMENT






                                       28
<PAGE>   30


         This Lease contains all of the agreements between Landlord and Tenant
with respect to the Premises and supersedes all prior writings and dealings
between them with respect thereto.

         8.13     NO AGREEMENT UNTIL SIGNED

         The submission of this Lease or a summary of some or all of its
provisions for examination does not constitute a reservation of or option for
the Premises or an offer to lease and no legal obligations shall arise with
respect to the Premises or other matters herein until this Lease is executed and
delivered by Landlord and Tenant.

         8.14     TENANT'S AUTHORIZED REPRESENTATIVE

         Tenant designates the person named from time to time as Tenant's
Authorized Representative to take all acts of Tenant hereunder. Landlord may
rely on the acts of such Authorized Representative without further inquiry or
evidence of authority. Tenant's Authorized Representative shall be the person so
designated in Section 1.1 and such successors as may be named from time to time
by the then current Tenant's Authorized Representative or by Tenant's president.

         8.15     NOTICE OF LEASE

         Landlord and Tenant agree not to record this Lease. If appropriate,
both parties will, at the request of either, execute, acknowledge and deliver a
Notice of Lease and a Notice of Termination of Lease Term, each in recordable
form. Such notices shall contain only the information required by law for
recording. Tenant hereby irrevocably appoints Landlord as Tenant's
attorney-in-fact (which appointment shall survive termination of the Term) with
full power of substitution to execute, acknowledge and deliver a notice of
termination of lease on Tenant's name if Tenant fails to do so within 10 days
after request therefor.

         8.16     TENANT AS BUSINESS ENTITY

         If Tenant is a business entity, then Tenant warrants and represents
that (a) Tenant is duly organized, validly existing and in good standing under
the laws of the jurisdiction in which such entity was organized; (b) Tenant has
the authority to own its property and to carry on its business as contemplated
under this Lease; (c) Tenant is in compliance with all laws and orders of public
authorities applicable to Tenant; (d) Tenant has duly executed and delivered
this lease; (e) the execution, delivery and performance by Tenant of this Lease
(i) are within the powers of Tenant, (ii) have been duly authorized by all
requisite action, (iii) will not violate any provision of law or any order of
any court or agency of government, or any agreement or other instrument to which
Tenant is a party or by which it or any of its property is bound, and (iv) will
not









                                       29
<PAGE>   31
result in the imposition of any lien or charge on any of Tenant's property,
except by the provisions of this Lease; and (v) the Lease is a valid and binding
obligation of Tenant in accordance with its terms subject to bankruptcy and
creditors' rights, laws and general principles of equity. Tenant, if a business
entity, agrees that breach of the foregoing warranty and representation shall at
Landlord's election be a default under this Lease for which there shall be no
cure. This warranty and representation shall survive the termination of the
Term.

         8.17     RELOCATION

         If the Premises contain 3,500 rentable square feet or less, Landlord
reserves the right to relocate the Premises to comparable space within the
Building by giving Tenant prior notice of such intention to relocate. If within
one month after receipt of such notice Tenant has not agreed with Landlord on
the space to which the Premises are to be relocated, the timing of such
relocation and the terms of such relocation, then Landlord shall have the option
either to withdraw its relocation notice or to terminate this Lease on a date
which is at least 60 days after the date of the original notice (such date to
take effect as though the Lease had then expired).

         If Landlord and Tenant do so agree on relocation, then, effective on
the date of such relocation, this Lease shall be amended by deleting the
description of the original Premises and the Rentable Floor Area of Premises set
forth in Section 1.1 and substituting therefor information relating to such
relocation space. Landlord agrees to pay the reasonable cost of moving Tenant to
such other space and finishing such space to a condition comparable to the then
condition of the Premises.

         8.18     SECURITY DEPOSIT

         On the execution of this Lease, Tenant shall pay to Landlord as a
security deposit for the performance of the obligations of Tenant hereunder any
amount specified therefor in Section 1.1. Said security deposit may be mingled
with other funds of Landlord and no fiduciary relationship shall be created with
respect to such deposit, nor shall Landlord be liable to pay Tenant interest
thereon. If Tenant shall fail to perform any of its obligations under this
Lease, Landlord may, but shall not be obliged to, apply the security deposit to
the extent necessary to cure the default, and Tenant shall be obligated to
reinstate such security deposit to the original amount thereof upon demand.
Within thirty (30) days after the expiration or sooner termination of the Term
the security deposit, to the extent not applied, shall be returned to the
Tenant, without interest.

         8.19    GUARANTY





                                       30
<PAGE>   32

         The Tenant is a wholly-owned subsidiary of Altarex Corporation, a
Canadian corporation. As part of the execution of this Lease by Tenant, Altarex
Corporation has agreed to guaranty the obligations and debts of Tenant by
executing a Guaranty in the form attached hereto as Exhibit F.

         8.20     MISCELLANEOUS PROVISIONS

         This Lease may be executed in counterparts and shall constitute the
agreement of Landlord and Tenant whether or not their signatures appear in a
single copy hereof. This Lease shall be construed as a sealed instrument and
shall be governed exclusively by the provisions hereof and by the laws of The
Commonwealth of Massachusetts as the same may from time to time exist. The
titles are for convenience only and shall not be considered a part of the Lease.
Where the phrases "persons acting under Tenant" or "persons claiming under
Tenant" or similar phrases are used, the persons included shall be all
employees, agents, independent contractors and invitees of Tenant or of any
Subtenant of Tenant. The enumeration of specific examples of or inclusions in a
general provision shall not be construed as a limitation of the general
provision. If Tenant is granted any extension option, expansion option or other
right or option, the exercise of such right or option (and notice thereof) must
be unconditional to be effective, time always being of the essence to the
exercise of such right or option; and if Tenant purports to condition the
exercise of any option or to vary its terms in any manner, then the option
granted shall be void and the purported exercise shall be ineffective. Unless
otherwise stated herein, any consent or approval required hereunder may be given
or withheld in the sole absolute discretion of the party whose consent or
approval is required. Nothing herein shall be construed as creating the
relationship between Landlord and Tenant of principal and agent, or of partners
or joint venturers or any relationship other than landlord and tenant. This
Lease and all consents, notices, approvals and all other documents relating
hereto may be reproduced by any party by photographic, microfilm, microfiche or
other reproduction process and the originals thereof may be destroyed; and each
party agrees that any reproductions shall be admissible in evidence as the
original itself in any judicial or administrative proceeding (whether or not the
original is in existence and whether or not reproduction was made in the regular
course of business) and that any further reproduction of such reproduction shall
likewise be admissible in evidence. This Lease may be amended only by a writing
signed by all of the parties hereto.


                                   ARTICLE IX

                LANDLORD'S LIABILITY AND ASSIGNMENT FOR FINANCING

         9.1      LANDLORD'S LIABILITY






                                       31
<PAGE>   33


         Tenant agrees from time to time to look only to Landlord's interest in
the Land and Building for satisfaction of any claim against Landlord hereunder
or under any other instrument related to the Lease (including any separate
agreements among the parties and any notices or certificates delivered by
Landlord) and not to any other property or assets of Landlord. If Landlord from
time to time transfers its interest in the Land and Building (or part thereof
which includes the Premises), then from and after each such transfer Tenant
shall look solely to the interests in the Land and Building of each of
Landlord's transferees for the performance of all of the obligations of Landlord
hereunder (or under any related instrument). The obligations of Landlord shall
not be binding on any partners (or trustees or beneficiaries) of Landlord or of
any successor, individually, but only upon Landlord's or such successor's
interest described above.

         In no event shall Landlord ever be liable for any indirect or
consequential damages.

         9.2      ASSIGNMENT OF RENTS

         If, at any time and from time to time, Landlord assigns this Lease or
the rents payable hereunder to the holder of any mortgage on the Building, or to
any other party for the purpose of securing financing (the holder of any such
mortgage and any other such financing party are referred to herein as the
"Financing Party"), whether such assignment is conditional in nature or
otherwise, the following provisions shall apply:

         (i)   Such assignment to the Financing Party shall not be deemed an
assumption by the Financing Party of any obligations of Landlord hereunder
unless such Financing Party shall, by written notice to Tenant, specifically
otherwise elect;

         (ii)  Except as provided in (i) above and (iii) below, the Financing
Party shall be treated as having assumed Landlord's obligations hereunder
(subject to Section 9.1) only upon foreclosure of its mortgage (or voluntary
conveyance by deed in lieu thereof) and the taking of possession of the Premises
from and after foreclosure and, with respect to obligations regarding return of
the security deposit, only upon receipt of the funds constituting such security
deposit;

         (iii) Subject to Section 9.1, the Financing Party shall be responsible
for only such breaches under the Lease by Landlord which occur during the period
of ownership by the Financing Party after such foreclosure (or voluntary
conveyance by deed in lieu thereof) and taking of possession, as aforesaid;

         (iv)  In the event Tenant alleges that Landlord is in default under any
of Landlord's obligations under this Lease, Tenant agrees to give the holder of
any mortgage, by registered mail, a copy of any notice of default which is
served upon the Landlord, provided that prior to such notice, Tenant has been
notified, in writing,







                                       32
<PAGE>   34

(whether by way of notice of an assignment of lease, request to execute an
estoppel letter, or otherwise) of the address of any such holder. Tenant further
agrees that if Landlord shall have failed to cure such default within the time
provided by law or such additional time as may be provided in such notice to
Landlord, such holder shall have sixty (60) days after the last date on which
Landlord could have cured such default within which such holder will be
permitted to cure such default. If such default cannot be cured within such
sixty-day period, then such holder shall have such additional time as may be
necessary to cure such default, if within such sixty day period such holder has
commenced and is diligently pursuing the remedies necessary to effect such cure
(including, but not limited to, commencement of foreclosure proceedings, if
necessary, to effect such cure), in which event Tenant shall have no right with
respect to such default while such remedies are being diligently pursued by such
holder.

         In all events, any liability of a Financing Party shall be limited to
the interest of such Financing Party in the Land and Building, and in no event
shall a Financing Party ever be liable for any indirect or consequential
damages.

         Tenant hereby agrees to enter into such agreements or instruments as
may, from time to time, be requested in confirmation of the foregoing.

         Without limiting the generality of the foregoing, Tenant acknowledges
that Landlord's interest in this Lease has been assigned to Principal Mutual
Life Insurance Company ("Principal") pursuant to an Assignment of Leases and
Rents dated November 25, 1996 ("Lease Assignment") and recorded with the
Middlesex South Registry of Deeds as Instrument Number 737 on November 25, 1996.
Until the Lease Assignment is discharged of record, Tenant shall, upon notice by
Principal, make payments under this Lease as directed by Principal. Unless and
until such notice is given by Principal, all payments shall be made as set forth
in Section 2.5.

                                   ARTICLE X

                        SUBORDINATION AND NON-DISTURBANCE

         This Lease shall be subject and subordinate to any first mortgage and
to any junior mortgage that has been approved by the first mortgagee that may
now or hereafter be placed upon the Building and/or the Land and to any and all
advances to be made under such mortgages and to the interest thereon, and all
renewals, extensions and consolidations thereof. Any mortgagee may elect to give
this Lease priority to its mortgage, except that the Lease shall not have
priority to (i) the prior right, claim and lien of such mortgagees in, to and
upon any insurance proceeds and the disposition thereof under the mortgage; (ii)
the prior right, claim and lien of such mortgagees in, to and upon any award or
compensation heretofore or hereafter to be made for any taking by eminent domain
of any part of the Premises, and to the right of disposition thereof







                                       33
<PAGE>   35

under the mortgage; and (iii)any lien, right, power or interest, if any, which
may have arisen or intervened in the period between the recording of the
mortgages and the execution of this Lease, or any lien or judgment which may
arise any time under the terms of this Lease. In the event of such election and
upon notification by such mortgagee, this Lease shall be deemed prior in lien to
the said mortgage. This Section shall be self-operative, but in confirmation
thereof, Tenant shall execute and deliver the Subordination, Nondisturbance and
Attornment Agreement attached as Exhibit E or whatever other instruments may be
required by the first mortgagee or junior mortgagee to acknowledge such
subordination or priority in a recordable form, and if Tenant fails to do so
within ten (10) days after demand, Tenant hereby irrevocably appoints Landlord
as Tenant's attorney-in-fact, in its name, place and stead to do so.


                                   ARTICLE XI

                                     PARKING

         11.1     GENERAL

         Landlord agrees to provide an automobile parking area during the term
of this Lease for the benefit and use of the customers and employees of Tenant,
and other tenants and occupants of the Building. Wherever the words "automobile
parking area" are used in this Lease, it is intended that the same shall
include, whether in a surface parking area or a parking structure, the
automobile parking stalls, driveways, entrances, exits, sidewalks, landscaped
areas, pedestrian passageways in conjunction therewith and other areas
designated for parking. Landlord shall keep the automobile parking area neat,
clean and in good repair, properly lighted and landscaped. Nothing contained
herein shall be deemed to create liability upon Landlord for any damage to motor
vehicles of customers or employees or from loss of property from within such
motor vehicles, unless caused by the negligence of Landlord, its agents,
servants and employees. Landlord shall have the right to establish and enforce
against all users of the automobile parking area, such reasonable rules and
regulations as may be deemed necessary and advisable for the proper and
efficient operation and maintenance of the automobile parking area, including
the hours during which the automobile parking area shall be open for use.

         Landlord may establish for the automobile parking area, a system or
systems of validation or other operation including, but not limited to, a system
of charges against nonvalidated parking checks of users, which validation
parking system shall guarantee Tenant at least eleven (11) parking spaces at all
times free of charge during the term of the Lease. Tenant shall comply with such
system, and all rules and regulations established by Landlord in conjunction
with such system, and shall cause its customers and employees to comply
therewith; provided, however, that such system and such rules









                                       34
<PAGE>   36

and regulations shall apply equally and without discrimination to all persons
entitled to the use of the automobile parking area.

         Landlord shall at all times during the term hereof have the sole and
exclusive control of the automobile parking area, and may at any time during the
term hereof exclude and restrain any person from use thereof; excepting,
however, Tenant and its employees, bona fide customers, patrons and service
suppliers of Tenant and other tenants of Landlord who make use of said area in
accordance with any rules and regulations established by Landlord from time to
time with respect thereto. Landlord shall also have the right to designate
certain automobile parking areas as being for the exclusive use of one or more
of the tenants of Landlord. The rights of Tenant referred to in this Article
shall at all times be subject to the rights of Landlord and the other tenants of
Landlord to use the same in common with Tenant, and it shall be the duty of
Tenant to keep all of said area free and clear of any obstructions created or
permitted by Tenant or resulting from Tenant's operations and to permit the use
of any of said area only for normal parking and ingress and egress by said
customers, patrons and service suppliers to and from the Building.

         Landlord shall at all times have the right and privilege of determining
the nature and extent of the automobile parking area, whether the same shall be
surface, underground or other structure, and of making such changes therein from
time to time which in its opinion are deemed to be desirable and for the best
interests of all persons using the automobile parking area.

         11.2     EMPLOYEE PARKING

         It is understood and agreed that the employees of Tenant and the other
tenants of Landlord within the Building shall not be permitted to park their
automobiles in the portions of the automobile parking area which may from time
to time be designated for patrons of the Building and that Landlord shall at all
times have the right to establish rules and regulations for employee parking.

         11.3     PATRON PARKING

         Landlord agrees to provide within the automobile parking area parking
spaces for the patrons of Tenant and other tenants in the Building in sufficient
number as from time to time Landlord shall reasonably deem appropriate.

         11.4     OTHER PARKING USERS

         Landlord may authorize persons other than those described above,
including occupants of other buildings, to utilize said automobile parking area.







                                       35
<PAGE>   37

  Executed to take effect as a sealed instrument.


                                      275 Wyman Street Trust


                                      By: /s/ Michael D. Bank
                                         --------------------------------
                                         Managing Trustee


                                      ALTAREX, U.S. Corp.

                                      By: /s/ Richard E. Bagley
                                         --------------------------------
                                         Name:   Richard E. Bagley
                                         Title:  President/CEO

                                      By:
                                         --------------------------------
                                         Name:
                                         Title:  Treasurer/Assistant Treasurer




                                       36