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                                                                   EXHIBIT 10.1


                                      LEASE

                                                   Date:   May 15, 1997

                                     MAI238

I.   MASSACHUSETTS INSTITUTE OF TECHNOLOGY, a Massachusetts Corporation,
successors and assigns, "Lessor", hereby LEASES unto MILLENNIUM PHARMACEUTICALS,
"Lessee", the following Premises: Suite #500 and 402, containing approximately
20,652 rentable square feet of space on the fourth and fifth floors, and known
as the "Premises", identified as the hatched areas on EXHIBIT A, located in the
"Building" identified as number 238 Main Street, Cambridge, Massachusetts, the
"Building", which Building contains 77,697 rentable square feet and is located
on the parcel of land (the "Land") identified as Assessors Plan #47, Lot #84 as
shown on the plan attached hereto as EXHIBIT B; subject to existing easements
and party wall agreements and to rights and encumbrances of record, and the
Lessor reserves the right to maintain, use, repair and replace pipes, ducts,
wires, meters and any other equipment, machinery, apparatus and fixtures serving
other parts thereof, provided that the Lessor shall minimize any interference to
Lessee with respect thereto.

II.  TO HAVE AND TO HOLD for the term:

beginning with the Fifteenth day of May, 1997, and ending with the Thirty First
day of May, 1999, identified as the "Term", as herein under specified unless
sooner terminated as hereinafter provided, and to be used for the following
purpose:

                                     Offices

III. YIELDING AND PAYING a rent of Five Hundred Ninety Eight Thousand Eight
Hundred Sixty and 00/100 Dollars ($598,860.00) yearly by equal monthly payments
of Forty Nine Thousand Nine Hundred Five and 00/100 Dollars ($49,905.00) Dollars
per month, known as "Base Rent", on the first day in each calendar month in
advance, the first monthly payment to be prorated and paid effective May 15,
1997, all payments to be made to the Lessor or such agent, and at such place, as
the Lessor shall from time to time in writing designate, the following being now
so designated:


                              Meredith & Grew, Inc.
                               160 Federal Street
                              Boston, MA 02110-1701



It is also understood and agreed as follows:

1.       REAL ESTATE TAXES: Lessee shall pay, as additional rent, 26.58 percent
         of the increase in real estate taxes assessed on the Land and Building
         by the City of Cambridge during the

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         Lease term and any extension thereof. If in any tax year commencing
         with the Fiscal Year 1998 (July 1, 1997 - June 30, 1998), the real
         estate taxes on the Land and Building of which the leased Premises are
         a part are in excess of the amount of the real estate taxes thereon for
         the Fiscal Year 1997 (July 1, 1996 - June 30, 1997), Lessee shall pay
         to Lessor as additional rent 26.58 percent of such excess that may
         occur in each year. Such payment shall be made by paying Lessor on each
         day that payments of basic rent are due hereunder, an amount equal to
         one-twelfth (1/12th) of the amount which Lessor reasonably estimates to
         be the total amount of Lessee's obligation under this section for that
         year, said estimate to be predicted on the previous year's taxes.
         Payments made by Lessee under this section shall not bear interest and
         may be commingled by Lessor with any other funds of Lessor. Taxes due
         hereunder for the years in which each of the term commencement date and
         the Lease termination date occurs shall be prorated. If the total
         amount paid hereunder with respect to any year exceeds the amount due
         under this section for such year, such excess shall be credited by
         Lessor against the monthly installments on account of taxes next
         falling due, if any, or if no further payments on account of taxes will
         become due during the remainder of the term of this Lease, Lessor shall
         promptly refund the amount of such excess to Lessee upon the expiration
         or termination of this Lease (unless such termination is a result of a
         default by Lessee, in which case such amount shall be set off against
         amounts due to Lessor from Lessee). If the aggregate amount of
         installments paid by Lessee on account of taxes with respect to any
         year is less than Lessee's prorata share thereof for such year, Lessor
         shall give written notice thereof to Lessee, and Lessee shall pay to
         Lessor the amount of such deficiency, as additional rent, within ten
         (10) days of receipt of notice. Upon request by Lessee, Lessor shall
         promptly furnish to Lessee a copy of Real Estate Tax Bill of Building,
         but Lessee's obligation to make payments on account of taxes shall not
         be conditioned upon receipt by Lessee of this bill.

2.       OPERATING EXPENSES: Lessee shall pay, as additional rent, 26.58 percent
         of the increase in operating expenses for the Land and Building of
         which the leased Premises are a part, above the base operating expenses
         for the Fiscal Year 1996. At the end of the first fiscal year* and at
         the end of each succeeding fiscal year during the Term, Lessor shall
         render to Lessee a statement of operating expenses for the preceding
         year.


* Currently July 1 - June 30. Lessor reserves the right to change the fiscal
year dates at any time in during the Lease Term.
         Within thirty (30) days after the date of delivery of such statement,
         Lessee shall pay to Lessor, as additional rent, any amount due. In
         addition, Lessor shall deliver to Lessee a budget for the then current
         fiscal year based on the statement of expenses for the prior year and
         projected increases or decreases reasonably estimated by Lessor.
         Commencing with the first day of the first month following the delivery
         to the Lessee of such budget, the Lessee shall pay to the Lessor on
         account toward Lessee's share of increases in operating expenses
         anticipated for the then current year, 1/12 of the total annualized


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         amount by which the operating expenses exceed the base year expenses.
         At the end of the fiscal year, Lessor shall provide to Lessee a
         reconciliation of actual operating costs compared to budgeted costs and
         adjust Lessee's account accordingly.

         In the event that the average occupancy rate of the building shall be
         less than ninety-five percent (95%) for any fiscal year, for purposes
         of calculating operating expense increases, the operating expenses for
         such fiscal year shall be increased by the additional costs and
         expenses that Lessor reasonably estimates would have been incurred if
         the average occupancy rate had been ninety-five percent (95%) for such
         fiscal year. It is not the intent of this provision, commonly referred
         to as a "gross up" clause, to permit Lessor to charge Lessee for any
         operating expenses attributable to unoccupied space, or to seek
         reimbursement form Lessee for costs never incurred. Rather, the intent
         of this provision is to allow the Lessor to recover only those
         increases in operating expenses properly attributable to the occupied
         space in the building, and this provision is thus designed to calculate
         the actual cost of providing a variable operating expense service to
         the leased area of the Building receiving such service. The "gross up"
         treatment shall be applied only with respect to variable operating
         expenses arising from services provided to space in the Building
         occupied by Lessees (which services are not provided to space or may be
         provided only to some Lessees) in order to equitably allocate such
         variable operating expenses tot he Lessees receiving benefits thereof.

         Operating expenses shall include without limitation all utility,
         mechanical system, general operating, payroll, and administrative
         expenses including but not limited to:

         a)    All salaries, wages, fringe benefits, payroll taxes, and
               workman's compensation insurance premiums related thereto of and
               for employees engaged in the operation of the Building.

         b)    Cleaning; including window cleaning and the cost of cleaning 
               supplies.

         c)    Utilities; including all charges for electricity, water and
               sewer, and gas which are not separately chargeable to Building
               tenants.

         d)    Mechanical; including maintenance and repair for the heating
               and cooling, electrical systems.

         e)    General; including trash removal, roof repairs, security, and 
               snow removal.

         f)    Administrative; including management fee.

3.       LEASE TERMINATION: Lessee may terminate this Lease anytime after the 
         first anniversary of this Lease commencement, by providing written
         notice to Lessor six months in advance of the Lease termination date.

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4.       LEASE OPTION: Lessee has the option to extend this Lease for an
         additional two years at the then fair market value for office rents in
         the Kendall Square market, provided Lessee requests the extended term
         in writing, not less than six months prior to the end of the initial
         Lease Term.

5.       PARKING: Lessor agrees to provide nineteen parking spaces during
         the Lease Term and any extension thereof. The monthly rate for such
         parking will be $120.00 per space and is subject to change throughout
         the Term of the Lease. The monthly "rent" is to be equal to the parking
         rents effective for Building tenants at 238 Main Street.

6.       CONDITION OF PREMISES: Lessee accepts the Premises in "as is" 
         condition, except Lessor agrees to paint the Premises by May 15, 1997
         at no charge to Lessee.

7.       LATE PAYMENT OF RENT: Lessee agrees that in the event that any payment
         of annual fixed rent or additional rent shall remain unpaid at the
         close of business on the tenth business day of each month there shall
         become due to the Lessor from the Lessee, as additional rent and as
         compensation for the Lessor's extra administrative costs in
         investigating the circumstances of late rent, a late charge of two
         percent (2%) of the amount overdue. The Lessor shall notify, in
         writing, when said late fee is debited to Lessee's account.

8.       ASSIGNMENT/SUBLET: Except with respect to an assignment or sublease to
         a successor to Lessee by merger or acquisition or with respect to
         assignment or sublease to a majority owned subsidiary of Lessee ;
         Lessee shall not assign this Lease or sublet the Premises thereof, or
         permit the occupancy of any portion of the Premises without obtaining,
         on each occasion, the prior written consent of the Lessor, which
         consent shall not be unreasonably withheld. At the time Lessee provides
         written notice to Lessor of its proposal to assign this Lease or sublet
         the Premises thereof, Lessee shall provide Lessor with a copy of the
         proposed assignment or sublease document, and such information as
         Lessor may reasonably request concerning the proposed sublessee or
         assignee to assist Lessor in making an informed judgment regarding the
         financial condition, reputation, operation and general desirability of
         the proposed sublessee or assignee. Lessor shall not unreasonably
         withhold its consent to an assignment by another entity acquiring
         Lessee. Lessor shall then have a period of fifteen (15) days following
         receipt of such notice within which to notify Lessee in writing of
         Lessor's election to:

               1.   terminate this Lease as of the date specified by Lessee if
                    the space so affected comprises more than fifty percent
                    (50%) of the leased Premises, in which event Lessee shall be
                    relieved of all further obligations hereunder as to the
                    leased Premises or said portion thereof, after paying all
                    Rent due as of the Termination Date, or

               2.   permit Lessee to assign or sublet the leased Premises or 
                    said portion thereof, or

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               3.   refuse to consent to Lessee's assignment or subleasing of
                    the leased Premises or said portion thereof and to continue
                    this Lease in full force and effect as to the entire leased
                    Premises.

         If Lessee does assign, sublet, or permit occupancy hereunder, and if
         the aggregate rent and other amounts payable to Lessee under or in
         connection with such assignment, sublease, or occupancy arrangement,
         exceeds the rents and other charges said hereunder the Lessee shall pay
         to the Lessor the amount of 50% of such excess, as additional rent,
         less any out of pocket expenses that Lessee reasonably incurs.

9.       INSURANCE:

  9.1    PUBLIC LIABILITY INSURANCE: Lessee shall take out and maintain in force
         throughout the term comprehensive public liability insurance naming
         Lessor, Lessee, the holder of any mortgage, and persons claiming under
         them, if any, as insureds against all claims and demands for any injury
         to person or property which may be claimed to have occurred on the
         Premises, the Building, the Land and ways adjoining the Building, in an
         amount which at the beginning of the term shall not be less than
         $1,000,000 for injury or death of one person, $3,000,000 for injury or
         death of more than one person in a single accident and $1,000,000 for
         property damage or such higher amounts as Lessor shall determine are
         reasonably required by reason of Lessee's use of the Premises and which
         thereafter, if Lessor requires, shall be in such higher amounts as are
         then consistent with sound commercial practice in Cambridge,
         Massachusetts. Lessee's insurer shall be authorized to do business in
         Massachusetts and have a general policy holder's rating of not less
         than A and financial ratings of not less than Class VIII as rated in
         the most current "Best's Insurance Report".

 9.2     CASUALTY INSURANCE: Lessee shall take out and maintain throughout the
         term a policy of fire, vandalism, malicious mischief, extended coverage
         and so-called all risk coverage insurance insuring Lessee's
         improvements to the Premises and Lessee's fixtures, furnishing and
         equipment to their full insurable value, except that any such insurance
         may be written with an 80% co-insurance clause.

 9.3     CERTIFICATES OF INSURANCE: Such insurance shall be placed with insurers
         reasonably satisfactory to Lessor and authorized to do business in
         Massachusetts. Such insurance shall provide that it shall not be
         cancelled without at least ten (10) days prior written notice to each
         insured named therein. Lessee shall furnish to Lessor certificates of
         insurance for all insurance required to be maintained by Lessee under
         this Lease. Lessee shall also deliver such certificates to the holder
         of any mortgage affecting the Land and Building, said certificates
         setting forth in full the provisions thereof together with evidence
         satisfactory to Lessor of the payment of all premiums for such
         policies.

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 9.4     LESSOR'S INSURANCE: Lessor shall take out and maintain in force
         throughout the Lease Term, in a company or companies authorized to do
         business in Massachusetts, casualty insurance on the Building
         (excluding "Lessee's Property", "Lessee's Work" and "Alterations") (as
         hereinafter defined), as to which Lessee is required to maintain
         insurance pursuant to Section 9.2 above) in an amount equal to the full
         replacement value of the Building (exclusive of foundations and those
         items set forth in the preceding parenthetical in this sentence),
         covering all risks of direct physical loss or damage and so-called
         "extended coverage" risks. This insurance may be maintained in the form
         of a blanket policy covering the Building as well as other properties
         owned by Lessor. Notwithstanding the foregoing provisions of this
         Section 9.4, Lessor shall have the right, at any time during the Lease
         Term, to self-insure all or any portion of the coverages required by
         this Section.

 9.5     WAIVER OF SUBROGATION: To the extent to which a waiver of subrogation
         clause is available, Lessor and Lessee shall obtain a provision in all
         insurance policies carried by such party covering the Premises,
         including but not limited to contents, fire and casualty insurance,
         expressly waiving any right on the part of the insurer against the
         other party. If extra cost is chargeable for such provision, then the
         party benefitting from such waiver shall pay such extra charge.
         Notwithstanding the foregoing, with respect to such portion of the
         Lease Term during which Lessor elects to self-insure under Section 9.4
         above, then for purposes of this Section 9.5, Lessor shall be deemed to
         have maintained fire and all-risk coverage in an amount equal to one
         hundred (100%) percent of the insurable value of the Building (subject
         to the exceptions and exclusions set forth in Section 9.4 above) with a
         waiver of subrogation clause contained therein.

10.      REAL ESTATE BROKER: Lessor and Lessee each represent to the other that
         they have dealt with no broker in connection with this Lease. Lessee
         agrees to indemnify and hold Lessor harmless from and against any
         claims for commissions or fees by any person by reason of any act of
         Lessee or its representatives. Lessor agrees to indemnify and hold
         Lessee harmless from and against any claims for commissions or fees by
         any other person by reason of any act of Lessor or its representatives.

11.      RIGHTS OF GROUND LESSORS AND MORTGAGEES: No act or failure to act on
         the part of the Lessor which would entitle Lessee under the terms of
         this Lease or by law, to be relieved of Lessee's obligations hereunder
         or to terminate this Lease, shall result in a release or termination of
         such obligations or a termination of this Lease unless (i) Lessee shall
         have first given written notice to Lessor's ground lessors and
         mortgagees of record whose address has been provided by Lessor, of the
         act or failure to act on the part of Lessor which Lessee claims as the
         basis of Lessee's rights; and (ii) such ground lessors and mortgagees
         after receipt of such notice, have failed or refused to correct or cure
         the condition within a reasonable time thereafter, but nothing in this
         Lease shall be deeded to impose any obligation on any such ground
         lessor or mortgagee to correct or cure any such condition. No ground
         lessor shall be liable for the failure to perform any of the

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         obligations of Lessor hereunder unless and until such ground lessor
         terminates its ground lease and takes possession of the Premises, nor
         shall any mortgagee be liable for the failure to perform any of the
         obligations of Lessor hereunder unless and until such mortgagee enters
         upon and takes possession of the Premises for purposes of foreclosure.

12.      LEASE SUBORDINATE: This Lease is and shall be subject and subordinate
         to any ground lease or mortgage now or hereafter on the Premises, and
         to all advances under any such mortgage and to all renewals,
         amendments, extensions and consolidations thereof, provided that the
         holder of such ground lessor's interest or mortgagee's interest enters
         into a non-disturbance and attornment agreement with Lessee which
         provides that in the event that such ground lessor or mortgagee
         succeeds to Lessor's interest hereunder, then, provided that Lessee is
         not in default hereunder beyond the cure period provided in this Lease,
         such party shall recognize and be bound by the terms of this Lease. In
         the event that any ground lessor or the holder of any mortgage succeeds
         to Lessor's interest in the Premises or any portion thereof, Lessee
         hereby agrees to attorn to such ground lessor or mortgagee. In
         confirmation of such subordination, Lessee shall execute and deliver
         promptly any certificate in recordable form that Lessor or any ground
         lessor or any mortgagee may reasonably request. Notwithstanding the
         foregoing provisions of this Section, the holder of any mortgage on the
         Premises may at any time subordinate its mortgage to this Lease by
         written notice to Lessee.

         Lessor hereby represents to Lessee that as of the date of this Lease,
         there are no mortgages or ground leases encumbering the Premises or any
         portion thereof.

13.      NOTICE OF LEASE; ESTOPPEL CERTIFICATES: Lessor and Lessee agree
         that this Lease shall not be recorded. However, upon the request of
         either party, Lessor and Lessee shall execute and acknowledge a Notice
         of Lease in mutually acceptable and recordable form.

         From time to time during the Lease Term, and without charge, either
         party shall, within fifteen (15) business days of request by the other,
         certify by written instrument duly executed and acknowledged, to the
         requesting party or to any person reasonably specified by the
         requesting party, regarding (a) the existence of any amendments or
         supplements to this Lease; (b) the validity and force and effect of
         this Lease; (c) the existence of any known default or Event of Default;
         (d) the existence of any offsets, counterclaims or defenses; (e) the
         Commencement Date, the Rent Commencement Date and the expiration date
         of the Lease Term; (f) the amount of Rent due and payable and the date
         to which the Rent has been paid; and (g) such other matters as may be
         reasonably requested.

14.      QUIET ENJOYMENT: Provided Lessee has performed all its obligations
         under this Lease, including but not unlimited to the payment of Rent
         and all other sums due hereunder, Lessee shall peaceably and quietly
         hold and enjoy the leased Premises for the term, without hinderance by
         Lessor or anyone claiming by, through or under Lessor, subject to

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         the provisions and conditions set forth in this Lease.

15.      HOLDING OVER: If Lessee occupies the Premises after the day on which
         the Lease Term expires (or the effective date of any earlier
         termination as herein provided) without having entered into a new lease
         thereof with Lessor, Lessee shall be a tenant-at sufferance only,
         subject to all of the terms and provisions of this Lease one and one
         half (1 1/2) times the Basic Rent in effect on the day of such
         expiration or termination for the first one and one half (1 1/2) months
         of such holding over, even if with the consent of Lessor, shall not
         constitute an extension or renewal of this Lease.

16.      FORCE MAJEURE: Neither Lessor nor Lessee shall be deemed to be in
         default hereunder (and the time for performance of any of their
         respective obligations hereunder other than the payment of money shall
         be postponed) for so long as the performance of such obligation is
         prevented by strike, lockout, act of god, absence of materials or any
         other matter not reasonably within the control of the party which must
         perform the obligation (collectively, "Force Majeure").

17.      ENTIRE AGREEMENT: No oral statement or prior written matter shall have
         any force or effect. This Agreement shall not be modified or canceled
         except by writing subscribed to by all parties.

18.      EXHIBITS: Attached to and forming a part of this Lease are Exhibits 
         "A", "B", "C", "D".


IV. THE LESSEE acknowledges that said Premises are in good and satisfactory
order, repair and condition and that all glass is whole, and covenants during
said term and such further time as the Lessee holds any part of said Premises:

         (a)    to pay when due said rent and all charges for water, gas, and
                electricity, if applicable and to comply with any rules,
                reservations or conditions reasonably set forth by Lessor;

         (b)    damage by fire or unavoidable casualty excepted, to keep said
                Premises in as good order, repair and condition as the same are
                in at the commencement of said term, or may be put in thereafter
                and at the termination of this Lease peaceably to yield up said
                Premises and all additions thereto in such order, repair and
                condition, first removing all goods and effects except those of
                the Lessor and leaving the Premises clean and tenantable;

         (c)    damage by fire or casualty excepted, to keep all glass whole and
                in good condition with glass of the same quality as that injured
                or broken;

         (d)    not to injure, overload or deface said Premises or Building nor
                to permit on said

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                Premises any auction sale or any inflammable fluids or chemicals
                or any nuisance or the emission therefrom of any objectionable
                noise or odor nor to permit the use thereof for any purpose
                other than the purpose herein specified, nor any use thereof
                which is improper, offensive, contrary to law or ordinance, or
                liable to invalidate or increase the premiums for any insurance
                on the Building or its contents or liable to render necessary
                any alterations or additions to the Building;

         (e)    not to obstruct in any manner any portion of the Building not
                hereby leased or the sidewalks or approaches to said Building
                or any inside windows or doors, and to conform to all
                reasonable rules now or hereafter made by the Lessor for the
                care and use of the Building, its facilities and approaches;

         (f)    to keep the Premises equipped with all safety appliances and
                to procure all licenses and permits required by law or
                ordinance or any order or regulation of any public authority
                because of the particular use made of said Premises by the
                Lessee, and, if requested by the Lessor, to make all repairs,
                alterations, replacements or additions so required in and to
                the inside of said Premises;

         (g)    Lessee shall be permitted to make alterations within the
                leased Premises in amounts not to exceed $5,000. Lessee shall
                not make any alterations or additions or perform any
                construction work including demolition, electrical, plumbing,
                carpentry, HVAC or painting or to permit the making of any
                holes in any part of said Building or the painting or placing
                of any signs, awnings, aerials, or flagpoles or the like,
                visible from outside of said Premises that exceed $5,000.00
                without the express written consent of the Lessor, such
                consent not to be unreasonably withheld.

         (h)    to save the Lessor harmless and indemnified from any injury,
                loss, claim or damage to any person or property while on said
                Premises, if not due to negligence or misconduct of the
                Lessor, and to any person or property anywhere occasioned by
                any negligent omission, neglect or default of the Lessee or of
                employees of the Lessee;

         (i)    to permit the Lessor and the Lessor's agents to examine the
                Premises at reasonable times, and if the Lessor shall so
                elect, to make any repairs or additions the Lessor may deem
                necessary, and at the Lessee's expense to remove any
                alterations, additions, signs, awnings, aerials or flagpoles,
                or the like, not consented to in writing, and to show the
                Premises to prospective purchasers and tenants, during the
                nine months preceding the expiration of said term or any
                extension;

         (j)    in case the Lessee takes possession of said Premises prior to
                the commencement of said term, to perform and observe all of
                the Lessee's covenants from and after the date upon which the
                Lessee takes possession except that no rent shall accrue 

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                prior to the beginning of said term;

         (k)    not to permit any employee or visitor of the Lessee to violate
                any covenant or obligation of the Lessee hereunder;

         (l)    the Lessor shall not be held liable to anyone for cessation of
                any service rendered customarily to said Premises or Building or
                agreed to by the terms of this Lease, due to any accident, to
                the making of repairs, alterations or improvements, to labor
                difficulties, to trouble in obtaining fuel, electricity, service
                or supplies from the sources from which they are usually
                obtained for said Building, or to any cause beyond the Lessor's
                control.

         (m)    that Lessee will not dump, flush, or in any way introduce any 
                hazardous materials or oil or any other toxic substances into
                the septic, sewage or other waste disposal system serving the
                Premises (the foregoing shall not prevent the introduction of
                such substances into a waste disposal system specifically
                designed to receive such substances so long as said system is
                constructed and maintained in accordance with all applicable
                governmental regulations); and in the event of any such
                unpermitted introduction, will clean up promptly any damage
                occasioned by such. The Lessee further agrees it will not
                generate, store or use (except in accordance with all applicable
                governmental regulations) or dispose of hazardous materials or
                oil or toxic substances in or on the Premises, or dispose of
                hazardous materials or oil or toxic substances from the Premises
                to any other location, except a properly approved disposal
                facility and then only in compliance with any and all federal,
                state and local laws and ordinances regulating such activity.
                "Hazardous materials", "oil" and "toxic substances", as used in
                this Section, shall have the same meanings as defined and used
                in the Massachusetts Oil and Hazardous Material Release
                Prevention Act, as amended, M.G.L. ch. 21E, the Comprehensive
                Environmental Response, Compensation and Liability Act of 1980,
                as amended, 42 U.S.C. S9061 et seq.; in the Hazardous Materials
                Transportation Act, 49 U.S.C. S180; in the Toxic Substances Act,
                15 U.S.C. 8601 et seq.; and in the regulations adopted and
                publications promulgated pursuant to said Acts.

V.  PROVIDED ALWAYS that in case said Premises or Building or any substantial
part thereof shall be taken by any exercise of the right of eminent domain or
shall receive any direct or consequential or substantial damages for which the
Lessor or the Lessee or either of them shall be entitled to compensation by
reason of anything lawfully done in pursuance of any public or other authority
during this Lease or any extensions thereof, then this Lease shall terminate at
the election of the Lessor which election may be made notwithstanding the
Lessor's entire interest may have been divested; and if the Lessor shall not so
elect, then in case of such taking or damage rendering the Premises or any part
thereof unfit for use and occupation, a just proportion of said rent according
to the nature and extent of the injury shall be abated until the Premises or in
case of such taking what remains thereof shall be put in proper condition for
use and

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occupation. If such taking or damage substantially reduces the floor space of
the demised Premises the Lessee shall have the right, effective when its
possession is disturbed, to terminate the within Lease by notice in writing to
the Lessor delivered within 30 days of the first day on which the Lessee's
possession is so disturbed. The Lessor reserves and excepts all rights to damage
to said Premises and Building and the leasehold hereby created, now accrued or
hereafter accruing by reason of any exercise of eminent domain, or by reason of
anything lawfully done in pursuance of any public or other authority and by way
of confirmation, the Lessee grants to the Lessor all the Lessee's rights to such
damages and covenants to execute and deliver such further instruments of
assignment thereof as the Lessor may from time to time request. The Lessee shall
have the right to pursue claims for relocation expenses and personal property.
The Lessee shall have the right to pursue claims for relocation expenses and
personal property from the public authority stated above or Lessee's insurer. If
the demised Premises shall be substantially damaged by fire or unavoidable
casualty then either party may terminate this Lease as of the date of the
occurrence of such damage by written notice thereof to the other party given
within 10 days of the occurrence of such damage. In the event of any destruction
of or damage to the demised Premises by reason of fire or unavoidable casualty
rendering the same or any part thereof unfit for occupation and provided said
Lease has not been terminated as hereinbefore provided, a just proportion of the
rent hereinbefore reserved shall be suspended or abated, according to the nature
and extent of the injuries sustained by the demised Premises, until the demised
Premises shall be put in proper condition for use and occupation which the
Lessor covenants to commence without delay and to prosecute with all reasonable
despatch.

VI. PROVIDED ALSO, and this Lease is upon this condition, that if the Lessee
shall neglect or fail to perform or observe any of the Lessee's covenants for a
period of 30 days (except in the case of payment of money for a period of 10
days) after written notice thereof, or if the leasehold hereby created shall be
taken on execution, or by other process of law, or if any assignment shall be
made of the Lessee's property for the benefit of creditors, or if a receiver,
guardian, conservator, trustee in bankruptcy or similar officer shall be
appointed to take charge of all or any part of the Lessee's property by a court
of competent jurisdiction, or if the Lessee commits any act of bankruptcy, or if
a petition is filed by the Lessee under any bankruptcy law, or if a petition is
filed against the Lessee under any bankruptcy law and the same shall not be
dismissed within sixty (60) days from the date upon which it is filed, then, and
in any of said cases, the Lessor lawfully may immediately or at any time
thereafter and without demand or notice, enter upon the Premises or any part
thereof in the name of the whole and repossess the same as of the Lessor's
former estate and expel the Lessee and those claiming through or under the
Lessee and remove their effects, forcibly if necessary, without being deemed
guilty of any manner of trespass and without prejudice to any remedies which
might otherwise be used for arrears of rent or preceding

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<PAGE>   12



breach of covenant, and upon such entry this Lease shall terminate, and the
Lessee covenants that in case of such termination or in case of termination
under the provisions of statute by reason of the default of the Lessee, the
Lessee will forthwith pay to the Lessor as damages a sum equal to the amount by
which the rent and other payments called for hereunder for the remainder of the
original term and of any extension thereof exceed the fair rental value of said
Premises for the remainder of the original term and of any extension thereof and
in addition thereto will furthermore indemnify the Lessor during the remainder
of the original term and of any extension thereof against all loss and damage
suffered by reason of such termination however caused, first deducting any
damages paid as above provided, the loss and damage, if any, for each rent
payment period during the remainder of the original term and of any extension
thereof to be paid at the end of each such rent payment period.

VII. No consent or waiver, express or implied, by the Lessor, to or of any 
breach of any covenant, condition or duty of the Lessee, shall be construed as a
consent or waiver to or of any other breach of the same or any other covenant,
condition or duty. Any notice from the Lessor to the Lessee or from the Lessee
to the Lessor shall be deemed duly served if mailed by registered mail addressed
if to the Lessee at MILLENNIUM PHARMACEUTICALS, INC., 640 MEMORIAL DRIVE,
CAMBRIDGE, MA 02139; ATTN: MR. MARK LEVIN and to the Lessor at MASSACHUSETTS
INSTITUTE OF TECHNOLOGY, OFFICE OF THE TREASURER, 238 MAIN STREET, SUITE 200,
CAMBRIDGE, MA 02142; ATTN: MR. PHILIP A. TRUSSELL, WITH A COPY TO MEREDITH &
GREW, INC., AGENT FOR MIT, 160 FEDERAL STREET, BOSTON, MA 02110; ATTN: KRISTIN
E. BLOUNT. The customary registered mail receipt shall be conclusive evidence of
such service. The covenants and agreements of the Lessor and Lessee shall run
with the Land and be binding upon and inure to the benefit of them and their
respective heirs, executors, administrators, successors and assigns, but no
covenant or agreement of the Lessor, express or implied, shall be binding upon
any person except for defaults occurring during such person's period of
ownership nor binding individually upon any fiduciary, any shareholder or any
beneficiary under any trust. If the Lessee is several persons or a partnership,
the Lessee's obligations are joint or partnership and also several. Unless
repugnant to the context, "Lessor" and "Lessee" mean the person or persons,
natural or corporate, named above as Lessor and as Lessee respectively, and
their respective heirs, executors, administrators, successors and assigns.









Witness the execution hereof in duplicate under seal the day and year first
above written.


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<PAGE>   13


                                   MASSACHUSETTS INSTITUTE OF TECHNOLOGY
                                   LESSOR


                                       /s/ Philip A. Trussell
DATE:______________________        BY:__________________________________
                                      Philip A. Trussell
                                      Director of Real Estate









                                   MILLENNIUM PHARMACEUTICALS, INC.
                                   LESSEE



                                      /s/ Mark A. Levin
DATE:______________________        BY:__________________________________
                                      Mark A. Levin
                                      President & Chief Executive Officer










                                    EXHIBIT C
                                    ---------

The Lessor shall provide the following services to the leased Premises:

1.     Heating and air conditioning equipment for the Premises, as demised,
       for normal office hours of 9:00 a.m. to 5:00 p.m., Monday through
       Friday, except on National or State Holidays. Excluded from such
       services are air conditioning requirements for computers

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<PAGE>   14


       or other special office machinery. After hours HVAC services will be made
       available to the Lessee for an additional charge as specified in Exhibit
       D. Such charges shall be paid to the Lessor as additional rent as
       provided herein.

2.     Maintenance and repair of all Building heating equipment, electrical
       equipment, plumbing systems in public areas only; all Building air
       conditioning equipment; all window frames and glass, unless the damage
       to any of the above is caused by the willful neglect or misuse by the
       Lessee.

3.     Nightly (Monday - Friday) cleaning of the Premises and public corridors,
       stairwells, lobbies, bathrooms, and cleaning of the windows, both inside
       and out, two (2) times per year.

4.     Extermination of all public and tenanted areas of the Building, as the 
       management of the Building deems necessary.

5.     Structural maintenance of the leased Premises including repairs to the 
       roof, exterior walls of the Building, and structural damage to the
       floors.

6.     The removal of any normal amount of office trash, Monday through Friday,
       in a "normal workday". Normal workday trash shall not include trash
       generated when a tenant moves in or out of the Building, when equipment
       is thrown away, when files are purged, or when construction is going on
       within the leased Premises.

7.     Lettering for one name in the Building directory located in the main 
       lobby.

8.     One sign, similar to the Lessor's standard signage, which lists the
       Lessee's company name and suite number and which shall be located
       adjacent to the Lessee's main entrance to the Premises.

9.     Snow removal and other services as deemed necessary by the Lessor for the
       normal operating of the Building.


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<PAGE>   15



                                    EXHIBIT D


The Lessee shall provide and pay for the following services at the Building:


1.     All maintenance of and repairs to the leased Premises necessary to keep
       the Premises in good condition or in as good a condition as the Premises
       were at the beginning of the Lease term. Such repairs and maintenance
       which shall be the Lessee's responsibility, and which shall be subject to
       the Lessor's approval, shall include but not be limited to the following:

       a.    The maintenance and repair of all electrical wiring, the outlets,
             switches and light fixtures within the leased Premises;

       b.    The maintenance and repair of all hardware within the leased 
             Premises;

       c.    The maintenance and repair of all walls, doors, ceilings, and
             floors;

       d.    The replacement of fluorescent light tubes and ballasts.  This
             service is available through Building Management on a time and
             material basis.

       e.    Lessee shall be obligated to pay a $15.00 per hour, per zone fee
             for HVAC needs exceeding normal operating hours as defined herein
             (Exhibit C).






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