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                                                                  Exhibit 10.1.1

                              THE RICHARDS BUILDING

                                64 Sidney Street
                            Cambridge, Massachusetts

                                    LANDLORD
================================================================================
                       FOREST CITY 64 SIDNEY STREET, INC.,
                               an Ohio Corporation

                                     TENANT
================================================================================
                               GENZYME CORPORATION

                               AMENDMENT TO LEASE

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                               AMENDMENT TO LEASE

     This AMENDMENT TO LEASE (the "Amendment") is entered into as of the 11th
day of September, 1995 by and between FOREST CITY 64 SIDNEY STREET, INC.
("Landlord") and Genzyme Corporation ("Tenant").

     WHEREAS, Landlord and Tenant's predecessor in interest, BioSurface
Technology, Inc., entered into a certain lease dated as of April 30, 1990, for
premises on the second and third floors of the Richards Building, which lease
was subsequently assigned to Tenant with Landlord's consent, (the "Lease"); and

     WHEREAS, Landlord and Tenant now desire to amend the Lease in order to
incorporate additional premises;

     In consideration of the mutual covenants contained herein, Landlord and
Tenant agree that the Lease is amended as follows:

     1.   DEFINITIONS
          The following terms have the meanings indicated below:

          "Area A Premises" means the area on the first floor of the building
          known and numbered as Suite 120, comprising 2,856 rentable square
          feet, as more particularly identified on Exhibit A.

          "Area B Premises" means the area on the first floor of the building
          known and numbered as Suite 150 (and including the so-called "Command
          Center"), comprising 4,827 rentable square feet, as more particularly
          identified on Exhibit A.

          "Area A Commencement Date" shall be the date hereof.

          "Area A Rent Commencement Date" shall be October 1, 1995

          "Area B Commencement Date" shall be the later of January 1, 1996, or
          such later delivery date of space to Tenant. In the event, Landlord is
          able to vacate the Area B Premises prior to January 1, 1996, Landlord
          shall deliver the space to Tenant on such earlier date, and in such
          case, the Area B rent shall commence on January 1, 1996.

          "Area A Annual Fixed Rent" shall be $28,560.

          "Area B Annual Fixed Rent" shall be $48,270.

          Capitalized terms used and not otherwise defined herein shall have the
          meanings ascribed to them in the Lease.

     2.   PREMISES AND TERM
          Commencing on the Area A Commencement Date, Landlord leases to Tenant
and Tenant leases from Landlord the Area A Premises, and from that date forward,
all references in the Lease to the

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Premises shall include the Area A Premises, except as set forth herein with
respect to the Area A Rent Commencement Date. Commencing on the Area B
Commencement Date, Landlord leases to Tenant and Tenant leases from Landlord the
Area B Premises, and from that date forward, all references in the Lease to the
Premises shall include the Area B Premises.

  3. RENT
     From and after the Area A Rent Commencement Date and the Area B
Commencement Date, the Tenant shall pay, without notice or demand, in advance on
the first day of every month, one-twelfth of the Annual Fixed Rent as set forth
above for the Area A Premises and the Area B Premises, respectively.

  4. REAL ESTATE TAXES AND OPERATING EXPENSES
     From and after the Area A Rent Commencement Date and the Area B
Commencement Date, Tenant shall be responsible to pay to Landlord, as Additional
Rent, the Tenant's Tax Expense Allocable for the Premises, and Operating
Expenses Allocable to the Premises, allocable to the Area A Premises and the
Area B Premises, respectively, in the same manner as set forth for the original
Premises.

  5. PARKING PRIVILEGES
     Beginning on the Area A Rent Commencement Date, Landlord shall provide and
Tenant shall pay for No 0 parking spaces, over and above those spaces allocated
to Tenant in accordance with the original Premises, at the market rates from
time to time in effect and in accordance with all other terms and conditions
governing parking as set forth in the Lease.

  6. CONDITION OF PREMISES; ALTERATIONS AND ADDITIONS
     The Area A Premises and the Area B Premises shall be provided to Tenant in
As-Is condition, except that Landlord shall be responsible for removing, prior
to the Area B Commencement Date, all furnishings and equipment in the Command
Center that forms a portion of the Area B Premises. All alterations and
additions to either the Area A Premises or the Area B Premises shall be the
responsibility of Tenant. Tenant may not commence any construction activities in
Area A or in Area B until after the appropriate commencement date. Tenant shall
be granted access to Area B, upon reasonable request to the then current
occupant, prior to the Area B Commencement Date for the purpose of preparing
plans and specifications. All alterations and additions, and all construction
work, shall be carried out in accordance with the terms of Article 4 of the
Lease.

  7. INCORPORATION AND BINDING EFFECT.
     The Lease is herein incorporated by reference and shall remain in full
force and effect, except as expressly modified herein. This Amendment to Lease
shall be binding upon and shall

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inure to the benefit of Landlord and Tenant and their respective successors and
assigns.

Executed as of the date first written above.

LANDLORD                                    TENANT

FOREST CITY 64 SIDNEY STREET, INC.          GENZYME CORPORATION

By: /s/ Gayle Friedland                     By:  /s/ Evan M. Lebson
   ------------------------                    ----------------------------

Its: Vice-President                         Its:  Vice-President, Treasurer
    -----------------------                     ---------------------------

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                                                                  Exhibit 10.1.2

                              THE RICHARDS BUILDING

                                64 Sidney Street
                            Cambridge, Massachusetts

                                    LANDLORD
================================================================================
                       FOREST CITY 64 SIDNEY STREET, INC.,
                               an Ohio Corporation

                                     TENANT
================================================================================
                               GENZYME CORPORATION

                            SECOND AMENDMENT TO LEASE

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                            SECOND AMENDMENT TO LEASE

     This SECOND AMENDMENT TO LEASE (the "Second Amendment") is entered into as
of the 1st day of March, 1996 by and between FOREST CITY 64 SIDNEY STREET, INC.
("Landlord") and GENZYME CORPORATION ("Tenant").

     WHEREAS, Landlord and Tenant's predecessor in interest, BioSurface
Technology, Inc., entered into a certain lease dated as of April 30, 1990, for
premises on the second and third floors of the Richards Building, which lease
was subsequently (i) assigned to Tenant with Landlord's consent, and (ii)
amended by Amendment to Lease Dated as of September 11, 1995 (the "First
Amendment"); and

     WHEREAS, Landlord and Tenant now desire to amend the Lease in order to
incorporate additional premises into the Area A Premises described in the First
Amendment;

     In consideration of the mutual covenants contained herein, Landlord and
Tenant agree that the Lease is amended as follows:

  1. As of March 1, 1996 (the "Area A Expansion Date"), the following
definitions set forth in the First Amendment shall be modified as follows:

     "Area A Premises" shall include both the original Area A Premises and the
     area identified on Exhibit A attached hereto as the "Area A Expansion
     Premises", and together shall comprise 3,421 rentable square feet.

     "Area A Annual Fixed Rent" shall be $34,210.00 per rentable square foot.

  2. PREMISES AND TERM
     Commencing on the Area A Expansion Date, Landlord leases to Tenant and
Tenant leases from Landlord the Area A Expansion Premises, and from that date
forward, all references in the Lease to the Premises or the Area A Premises
shall include the Area A Expansion Premises.

  3. RENT
     From and after the Area A Expansion Date, the Tenant shall pay, without
notice or demand, in advance on the first day of every month, one-twelfth of the
Area A Annual Fixed Rent as set forth above for the Area A Premises. Additional
Rent shall also be adjusted to reflected the adjusted size of the Area A
Premises.

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  4. CONDITION OF PREMISES; ALTERATIONS AND ADDITIONS
     The Area A Expansion Premises shall be provided to Tenant in As-Is
condition, and all alterations and additions shall be the responsibility of
Tenant. All alterations and additions, and all construction work, shall be
carried out in accordance with the terms of Article 4 of the Lease.

  5. INCORPORATION AND BINDING EFFECT.
     The Lease is herein incorporated by reference and shall remain in full
force and effect, except as expressly modified herein. This Second Amendment to
Lease shall be binding upon and shall inure to the benefit of Landlord and
Tenant and their respective successors and assigns.

Executed as of the date first written above.

LANDLORD                                    TENANT

FOREST CITY 64 SIDNEY STREET, INC.          GENZYME CORPORATION

By: /s/ Gayle Friedland                     By:  /s/ Evan M. Lebson
   ------------------------                    -------------------------------

Its:  Vice-President                        Its: VICE-PRESIDENT AND TREASURER
    -----------------------                     ------------------------------

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