Purchase Agreement

6.4 If no specific provision is made in Paragraph 5.1 for adjustment of the Contractor^’s Fee in the case of changes in the Work, or if the extent of such changes is such, in the aggregate, that application of the adjustment provisions of Paragraph 5.1 will cause substantial inequity to the Owner or Contractor, the Contractor’s Fee shall be equitably adjusted on the basis of the Fee established for the original Work, and the Guaranteed Maximum Price shall be adjusted accordingly.

ARTICLE 7 COSTS TO BE REIMBURSED

7.1      COST OF THE WORK

The term Cost of the Work shall mean costs necessarily incurred by the Contractor in the proper performance of the Work. Such costs shall be at rates not higher than the standard paid at the place of the Project except with prior consent of the Owner. The Cost of the Work shall include only the items set forth in this Article 7.

7.2      LABOR COSTS

7.2.1 Wages of construction workers directly employed by the Contractor to perform the construction of the Work at the site or, with the Owner’s approval, at off-site workshops.

7.2.2 Wages or salaries of the Contractor’s supervisory and administrative personnel when stationed at the site with the Owner^’s approval.

(If it is intended that the wages or salaries of certain personnel stationed at the Contractor’s principal or other offices shall be included in the Cost of the Work, identify in Article 14 the personnel to be included and whether for all or only part of their time, and the rates at which their time will be charged to the Work.)

7.2.3 Wages and salaries of the Contractor^’s supervisory or administrative personnel engaged, at factories, workshops or on the road, in expediting the production or transportation of materials or equipment required for the Work, but only for that portion of their time required for the Work.

7.2.4 Costs paid or incurred by the Contractor for taxes, insurance, contributions, assessments and benefits required by law or collective bargaining agreements and, for personnel not covered by such agreements, customary benefits such as sick leave, medical and health benefits, holidays, vacations and pensions, provided such costs are based on wages and salaries included in the Cost of the Work under Subparagraphs 7.2.1 through 7.2.3.

7.3      SUBCONTRACT COSTS

7.3.1 Payments made by the Contractor to Subcontractors in accordance with the requirements of the subcontracts.

7.4      COSTS OF MATERIALS AND EQUIPMENT INCORPORATED IN THE COMPLETED CONSTRUCTION

7.4.1 Costs, including transportation and storage, of materials and equipment incorporated or to be incorporated in the completed construction.

7.4.2 Costs of materials described in the preceding Subparagraph 7.4.1 in excess of those actually installed to allow for reasonable waste and spoilage. Unused excess materials, if any, shall become the Owner^’s property at the completion of the Work or, at the Owner^’s option, shall be sold by the Contractor. Any amounts realized from such sales shall be credited to the Owner as a deduction from the Cost of the Work.

7.5      COSTS OF OTHER MATERIALS AND EQUIPMENT, TEMPORARY FACILITIES AND RELATED ITEMS

7.5.1 Costs, including transportation and storage, installation, maintenance, dismantling and removal of materials, supplies, temporary facilities, machinery, equipment, and hand tools not customarily owned by construction workers, that are provided by the Contractor at the site and

fully consumed in the performance of the Work; and cost (less salvage value) of such items if not fully consumed, whether sold to others or retained by the Contractor. Cost for items previously used by the Contractor shall mean fair market value.

7.5.2 Rental charges for temporary facilities, machinery, equipment, and hand tools not customarily owned by construction workers that are provided by the Contractor at the site, whether rented from the Contractor or others, and costs of transportation, installation, minor repairs and replacements, dismantling and removal thereof. Rates and quantities of equipment rented shall be subject to the Owner’s prior approval.

7.5.3 Costs of removal of debris from the site.

7.5.4 Costs of document reproductions, facsimile transmissions and long-distance telephone calls, postage and parcel delivery charges, telephone service at the site and reasonable petty cash expenses of the site office.

7.5.5 That portion of the reasonable expenses of the Contractor’s personnel incurred while traveling in discharge of duties connected with the Work.

7.5.6 Costs of materials and equipment suitably stored off the site at a mutually acceptable location, if approved in advance by the Owner.

7.6                               MISCELLANEOUS COSTS

7.6.1 That portion of insurance and bond premiums that can be directly attributed to this Contract

7.6.2 Sales, use or similar taxes imposed by a governmental authority that are related to the. Work.

7.6.3 Fees and assessments for the building permit and for other permits, licenses and inspections for which the Contractor is required by the Contract Documents to pay.

7.6.4 Fees of laboratories for tests required by the Contract Documents, except those related to defective or nonconforming Work for which reimbursement is excluded by Subparagraph 13.5.3 of AIA Document ###-###-#### or other provisions of the Contract Documents, and which do not fall within the scope of Subparagraph 7.7.3.

7.6.5 Royalties and license fees paid for the use of a particular design, process or product required by the Contract Documents; the cost of defending suits or claims for infringement of patent rights arising from such requirement of the Contract Documents; and payments made in accordance with legal judgments against the Contractor resulting from such suits or claims and payments of settlements made with the Owner’s consent. However, such costs of legal defenses, judgments and settlements shall not be included in the calculation of the Contractor’s Fee or subject to the Guaranteed Maximum Price. If such royalties, fees and costs are excluded by the last sentence of Subparagraph 3.17.1 of AIA Document ###-###-#### or other provisions of the Contract Documents, then they shall not be included in the Cost of the Work.

7.6.6 Data processing costs related to the Work.

7.6.7 Deposits lost for causes other than the Contractor’s negligence or failure to fulfill a specific responsibility to the Owner as set forth in the Contract Documents.

7.6.8 Legal, mediation and arbitration costs, including attorneys’ fees, other than those arising from disputes between the Owner and Contractor, reasonably incurred by the Contractor in the performance of the Work and with the Owner^’s prior written approval; which approval shall not be unreasonably withheld.

7.6.9 Expenses incurred in accordance with the Contractor’s standard personnel policy for relocation and temporary living allowances of personnel required for the Work, if approved by the Owner.

7.7    OTHER COSTS AND EMERGENCIES

7.7.1 Other costs incurred in the performance of the Work if and to the extent approved in advance in writing by the Owner.

7.7.2 Costs due to emergencies incurred in taking action to prevent threatened damage, injury or loss in case of an emergency affecting the safety of persons and property, as provided in Paragraph 10.6 of AIA Document ###-###-####.

ARTICLE 8 COSTS NOT TO BE REIMBURSED

8.1  The Cost of the Work shall not include:

8.1.1 Salaries and other compensation of the Contractor^’s personnel stationed at the Contractor’s principal office or offices other than the site office, except as specifically provided in Subparagraphs 7.2.2 and 7.2.3 or as may be provided in Article 14.

8.1.2 Expenses of the Contractor’s principal office and offices other than the site office. 8.1.3 Overhead and general expenses, except as may be expressly included in Article 7.

8.1.4 The Contractor^’s capital expenses, including interest on the Contractor^’s capital employed For the Work.

8.1.5 Rental costs of machinery and equipment, except as specifically provided in Subparagraph 7.5.2.

8.1.6 Costs due to the negligence or Failure to fulfill a specific responsibility of the Contractor, Subcontractors and suppliers or anyone directly or indirectly employed by any of them or for whose acts any of them may be liable.

8.1.7 Any cost not specifically and expressly described in Article 7.

8.1.8 Costs, other than costs included in Change Orders approved by the Owner, that would cause the Guaranteed Maximum Price to be exceeded.

ARTICLE 9 DISCOUNTS, REBATES AND REFUNDS

9.1      Cash discounts obtained on payments made by the Contractor shall accrue to the Owner if (i) before making the payment, the Contractor included them in an Application for Payment

and received payment therefore from the Owner, or (2) the Owner has deposited funds with the Contractor with which to make payments; otherwise, cash discounts shall accrue to the Contractor. Trade discounts, rebates, refunds and amounts received from sales of surplus materials and equipment shall accrue to the Owner, and the Contractor shall make provisions so that they can be secured.

9.2    Amounts that accrue to the Owner in accordance with the provisions of Paragraph 9.1 shall be credited to the Owner as a deduction from the Cost of the Work.

ARTICLE 10 SUBCONTRACTS AND OTHER AGREEMENTS

10.1 Those portions of the Work that the Contractor does not customarily perform with the Contractor’s own personnel shall be performed under subcontracts or by other appropriate agreements with the Contractor. The Owner may designate specific persons or entities from whom the Contractor shall obtain bids. The Contractor shall obtain bids from Subcontractors and from suppliers of materials or equipment fabricated especially for the Work and shall deliver such bids to the Architect. The Owner shall then determine, with the advice of the Contractor and the Architect, which bids will be accepted. The Contractor shall not be required to contract with anyone to whom the Contractor has reasonable objection.

10.2 If a specific bidder among those whose bids are delivered by the Contractor to the Architect (i) is recommended to the Owner by the Contractor; (2) is qualified to perform that portion of the Work; and (3) has submitted a bid that conforms to the requirements of the Contract Documents without reservations or exceptions, but the Owner requires that another bid be accepted, then the Contractor may require that a Change Order be issued to adjust the Guaranteed Maximum Price by the difference between the bid of the person or entity recommended to the Owner by the Contractor and the amount of the subcontract or other agreement actually signed with the person or entity designated by the Owner.

10.3 Subcontracts or other agreements shall conform to the applicable payment provisions of this Agreement, and shall not be awarded on the basis of cost plus a fee without the prior consent of the Owner.

ARTICLE 11 ACCOUNTING RECORDS

The Contractor shall keep full and detailed accounts and exercise such controls as may be necessary for proper financial management under this Contract, and the accounting and control systems shall be satisfactory to the Owner. The Owner and the Owner’s accountants shall be afforded access to, and shall be permitted to audit and copy, the Contractor^’s records, books, correspondence, instructions, drawings, receipts, subcontracts, purchase orders, vouchers, memoranda and other data relating to this Contract, and the Contractor shall preserve these for a period of three years after final payment, or for such longer period as may be required by law.

ARTICLE 12 PAYMENTS

T2.1 PROGRESS PAYMENTS

12.1.1 Based upon Applications for Payment submitted to the Architect by the Contractor and Certificates for Payment issued by the Architect, the Owner shall make progress payments on account of the Contract Sum to the Contractor as provided below and elsewhere in the Contract Documents.

12.1.2 The period covered by each Application for Payment shall be one calendar month ending on the last day of the month, or as follows:

12.1.3 Provided that an Application for Payment is received by the Architect not later than the day of a month, the Owner shall make payment to the Contractor not later than the             day of the month. If an Application for Payment is received by the Architect after the application date fixed above, payment shall be made by the Owner not later than               days               after               the Architect receives the Application for Payment.

Requisitions shall be received by the Architect on or about the 1^st of each month. Payments are due from the Owner within 30 days of receipt of Requisition.

12.1.4 With each Application for Payment, the Contractor shall submit payrolls, petty cash accounts, receipted invoices or invoices with check vouchers attached, and any other evidence required by the Owner or Architect to demonstrate that cash disbursements already made by the Contractor on account of the Cost of the Work equal or exceed (i) progress payments already received by the Contractor; less (2) that portion of those payments attributable to the Contractor’s Fee; plus (3) payrolls for the period covered by the present Application for Payment. No application for payment shall include any amounts for labor or Work not yet performed or materials and/or equipment not yet incorporated into the Project (or delivered to and securely stored at the Project Site), or which are defective.

12.1.5 Each Application for Payment shall be based on the most recent schedule of values submitted by the Contractor in accordance with the Contract Documents. The schedule of values shall allocate the entire Guaranteed Maximum Price among the various portions of the Work, except that the Contractor’s Fee shall be shown as a single separate item. The schedule of values shall be prepared in such form and supported by such data to substantiate its accuracy as the Architect may require. This schedule, unless objected to by the Architect, shall be used as a basis for reviewing the Contractor’s Applications for Payment.

12.1.6 Applications for Payment shall show the percentage of completion of each portion of the Work as of the end of the period covered by the Application for Payment. The percentage of completion shall be the lesser of (1) the percentage of that portion of the Work which has actually been completed; or (2) the percentage obtained by dividing (a) the expense that has actually been incurred by the Contractor on account of that portion of the Work for which the Contractor has made or intends to make actual payment prior to the next Application for Payment by (b) the share of the Guaranteed Maximum Price allocated to that portion of the Work in the schedule of values.

12.1.7 Subject to other provisions of the Contract Documents, the amount of each progress payment shall be computed as follows:

.1  take that portion of the Guaranteed Maximum Price properly allocable to completed Work as determined by multiplying the percentage of completion of each portion of the Work by the share of the Guaranteed Maximum Price allocated to that portion of the Work in the schedule of values. Pending final determination of cost to the Owner of changes in the Work, amounts not in dispute shall be included as provided in Subparagraph 7.3.8 of AIA Document ###-###-####;

.2  add that portion of the Guaranteed Maximum Price properly allocable to materials and equipment delivered and suitably stored at the site for subsequent incorporation in the Work, or if approved in advance by the Owner, suitably stored off the site at a location agreed upon in writing;

 .3 add the Contractor’s Fee, less retainage of percent (10%)**. The Contractor’s Fee shall be computed upon the Cost of the Work described in the two preceding Clauses at the rate stated in Subparagraph 5.1.2 or, if the Contractor^’s Fee is stated as a fixed sum in that Subparagraph, shall be an amount that bears the same ratio to that fixed-sum fee as the Cost of the Work in the two preceding Clauses bears to a reasonable estimate of the probable Cost of the Work upon its completion;

.4  subtract the aggregate of previous payments made by the Owner;

.5  subtract the shortfall, if any, indicated by the Contractor in the documentation required by Paragraph 12.1.4 to substantiate prior Applications for Payment, or resulting from errors subsequently discovered by the Owner’s accountants in such documentation; and

.6  subtract amounts, if any, for which the Architect has withheld or nullified a Certificate for Payment as provided in Paragraph 9.5 of AIA Document ###-###-####.

**Retainage reduced to 5% after 50% completion

12.1.8 Except with the Owner’s prior approval, payments to Subcontractors shall be subject to retainage of not less than percent (10 %)**. The Owner and the Contractor shall agree upon a mutually acceptable procedure for review and approval of payments and retention for Subcontractors. **Retainage reduced to 5% after 50% completion

12.1.9 In taking action on the Contractor’s Applications for Payment, the Architect shall be entitled to rely on the accuracy and completeness of the information furnished by the Contractor and shall not be deemed to represent that the Architect has made a detailed examination, audit or arithmetic verification of the documentation submitted in accordance with Subparagraph 12.1.4 or other supporting data; that the Architect has made exhaustive or continuous on-site inspections or that the Architect has made examinations to ascertain how or for what purposes the Contractor has used amounts previously paid on account of the Contract. Such examinations, audits and verifications, if required by the Owner, will be performed by the Owner’s accountants acting in the sole interest of the Owner.

12.2 FINAL PAYMENT

12.2.1 Final payment, constituting the entire unpaid balance of the Contract Sum, shall be made by the Owner to the Contractor when:

.1  the Contractor has fully performed the Contract except for the Contractor^’s responsibility to correct Work as provided in Subparagraph 12.2.2 of AIA Document ###-###-####, and to satisfy other requirements, if any, which extend beyond final payment; and

.2 a final Certificate for Payment has been issued by the Architect.

12.2.2 The Owner’s final payment to the Contractor shall be made no later than 30 days after the issuance of the Architect’s final Certificate for Payment, or as follows: N/A

12.2.3 The Owner^’s accountants will review and report in writing on the Contractor^’s final accounting within 30 days after delivery of the final accounting to the Architect by the Contractor. Based upon such Cost of the Work as the Owner’s accountants report to be substantiated by the Contractor’s final accounting, and provided the other conditions of Subparagraph 12.2.1 have been met, the Architect will, within seven days after receipt of the written report of the Owner’s accountants, either issue to the Owner a final Certificate for Payment with a copy to the Contractor, or notify the Contractor and Owner in writing of the Architect^’s reasons for withholding a certificate as provided in Subparagraph 9.5.1 of the AIA Document ###-###-####. The time periods stated in this Subparagraph 12.2.3 supersede those stated in Subparagraph 9.4.1 of the AIA Document ###-###-####^.

12.2.4 If the Owner^’s accountants report the Cost of the Work as substantiated by the Contractor^’s final accounting to be less than claimed by the Contractor, the Contractor shall be entitled to demand arbitration of the disputed amount without a further decision of the Architect. Such demand for arbitration shall be made by the Contractor within 30 days after the Contractor^’s receipt of a copy of the Architect^’s final Certificate for Payment; failure to demand arbitration within this 3o-day period shall result in the substantiated amount reported by the Owner^’s accountants becoming binding on the Contractor. Pending a final resolution by arbitration, the Owner shall pay the Contractor the amount certified in the Architect^’s final Certificate for Payment.

12.2.5 If, subsequent to final payment and at the Owner^’s request, the Contractor incurs costs described in Article 7 and not excluded by Article 8 to correct defective or nonconforming Work,

the Owner shall reimburse the Contractor such costs and the Contractor’s Fee applicable thereto on the same basis as if such costs had been incurred prior to final payment, but not in excess of the Guaranteed Maximum Price. If the Contractor has participated in savings as provided in Paragraph 5.2, the amount of such savings shall be recalculated and appropriate credit given to the Owner in determining the net amount to be paid by the Owner to the Contractor.

ARTICLE 13 TERMINATION OR SUSPENSION

13.1 The Contract may be terminated by the Contractor, or by the Owner for convenience, as provided in Article 14 of AIA Document ###-###-####. However, the amount to be paid to the Contractor under Subparagraph 14.1.3 of AIA Document ###-###-#### shall not exceed the amount the Contractor would be entitled to receive under Paragraph 13.2 below.

13.2 The Contract may be terminated by the Owner for cause as provided in Article 14 of AIA Document ###-###-####. The amount, if any, to be paid to the Contractor under Subparagraph 14.2.4 of AIA Document ###-###-#### shall not cause the Guaranteed Maximum Price to be exceeded, nor shall it exceed an amount calculated as follows:

13.2.1 Take the Cost of the Work incurred by the Contractor to the date of termination;

13.2.2 Add the Contractor’s Fee computed upon the Cost of the Work to the date of termination at the rate stated in Subparagraph 5.1.2 or, if the Contractor’s Fee is stated as a fixed sum in that Subparagraph, an amount that bears the same ratio to that fixed-sum Fee as the Cost of the Work at the time of termination bears to a reasonable estimate of the probable Cost of the Work upon its completion; and

13.2.3 Subtract the aggregate of previous payments made by the Owner.

13.3 The Owner shall also pay the Contractor fair compensation, either by purchase or rental at the election of the Owner, for any equipment owned by the Contractor that the Owner elects to retain and that is not otherwise included in the Cost of the Work under Subparagraph 13.2.1. To the extent that the Owner elects to take legal assignment of subcontracts and purchase orders (including rental agreements), the Contractor shall, as a condition of receiving the payments referred to in this Article 13, execute and deliver all such papers and take all such steps, including the legal assignment of such subcontracts and other contractual rights of the Contractor, as the Owner may require for the purpose of fully vesting in the Owner the rights and benefits of the Contractor under such subcontracts or purchase orders.

13.4 The Work may be suspended by the Owner as provided in Article 14 of AIA Document ###-###-####; in such case, the Guaranteed Maximum Price and Contract Time shall be increased as provided in Subparagraph 14.3.2 of AIA Document ###-###-#### except that the term “profit” shall be understood to mean the Contractor’s Fee as described in Subparagraphs 5.1.2 and Paragraph 6.4 of this Agreement.

ARTICLE 14 MISCELLANEOUS PROVISIONS

14.1 Where reference is made in this Agreement to a provision AIA Document ###-###-#### or another Contract Document, the reference refers to that provision as amended or supplemented by other provisions of the Contract Documents.

14.2 Payments due and unpaid under the Contract shall bear interest from the date payment is due at the rate stated below, or in the absence thereof, at the legal rate prevailing from time to time at the place where the Project is located.

(Insert rate of interest agreed upon, if any.)

(Usury laws and requirements under the Federal Truth in Lending Act, similar state and local consumer credit laws and other regulations at the Owner’s and Contractor’s principal places of business, the location of the Project and elsewhere may affect the validity of this provision. Legal advice should be obtained with respect to deletions or modifications, and also regarding requirements such as written disclosures or waivers.)

14.5 Neither the Owner^’s nor the Contractor^’s representative shall be changed without ten days^’ written notice to the other party.

14.6   Other provisions:   N/A

ARTICLE 15 ENUMERATION OF CONTRACT DOCUMENTS

15.1     The Contract Documents, except for Modifications issued after execution of this Agreement, are enumerated as follows:

15.1.1 The Agreement is this executed 1997 edition of the Standard Form of Agreement Between Owner and Contractor, AIA Document AM-1997.

15.1.2 The General Conditions are the 1997 edition of the General Conditions of the Contract for Construction, AIA Document ###-###-####.

15.1.3 The Supplementary and other Conditions of the Contract are those contained in the Project Manual dated             , and are as follows:      N/A

15.1.4 The Specifications are those contained in the Project Manual dated as in Subparagraph 15.1.3, and are as follows:

(Either list the Specifications here or refer to an exhibit attached to this Agreement.)

No formal specifications were issued

15.1.5 The Drawings are as follows, and are dated different date is shown below:

(Either list the Drawings here or refer to an exhibit attached to this Agreement.)

SEE ATTACHED

15.1.6 The Addenda, if any, are as follows:

No formal specifications were issued

WARNING: Unlicensed photocopying violates U.S. copyright laws and will subject the violator to legal prosecution

Portions of Addenda relating to bidding requirements are not part of the Contract Documents unless the bidding requirements are also enumerated in this Article 15.

15.1.7 Other Documents, if any, forming part of the Contract Documents are as follows:

(List here any additional documents, such as a list of alternates that are intended to form part of the Contract Documents.AlA Document ###-###-#### provides that bidding requirements such as advertisement or invitation to bid, Instructions to Bidders, sample forms and the Contractor’s bid are not part of the Contract Documents unless enumerated in this Agreement. They should be listed here only if intended to be part of the Contract Documents.)

N/A

1997 AIA®

AIA DOCUMENT A111-1997

OWNER-CONTRACTOR AGREEMENT

The American Institute

of Architects

1735 New York Avenue, N.W.

Washington, D.C. 20006-5292

ARTICLE 16 INSURANCE AND BONDS

(List required limits of liability for insurance and bonds. AIA Document ###-###-#### gives other specific requirements for insurance and bonds.)

Contractor shall purchase from and maintain in a company or companies lawfully authorized to do business in the Commonwealth of Massachusetts and having an A.M. Best’s Insurance Rating of A:VIII or better, insurance for not less than the following, or greater if required by law:

Liability insurance shall include all major divisions of coverage and be of a comprehensive basis including:

1.              Premises Operations (including X-C/U as applicable).

2.              Independent Contractors’ Protective

3.              Products:  and Completed Operations

4.              Personal Injury Liability with Employment Exclusion deleted.

5.              Contractual-including specified provisions for the Contractor’s indemnification obligation Under the Contract Documents

6.     Broad form Property Damage including Completed Operations.

Contractor shall name Owner, Archemix Corporation (“Sublandlord”), Three Hundred Third Street LLC and BioMed Realty Trust, Inc. (collectively, “Master Landlord”) and Momenta Pharmaceuticals (“subtenant”), and any other interested party of whom Contractor shall be given written notice as an additional insurance on all liability policies of Contractor throughout the Project and for Completed Operations Coverage for an additional two year period after completion of the Work. The insurance policy shall be endorsed stating that such insurance shall be primary to and non-contributory with any other insurance maintained by Owner, Sublandlord or Master Landlord.

Contractor’s insurance shall provide that the insurer waives all rights of recovery or subrogation against Owner, Sublandlord and Master Landlord, and their officers, directors, employees, agents and insurers for (i) damages for injury to or death of persons; (ii) damage to property; and (iii) claims arising by reason of the foregoing due to hazards covered by insurance, to the extend of proceeds recovered therefrom.

Certificates of Insurance for all insurance required hereby shall be furnished by the Contractor to Owner, Sublandlord and Master Landlord before Contractor or any Subcontractor commences any Work and thereafter at least thirty (30) days prior to each cancellation, non-renewal or material reduction in coverage that causes the insurance to no longer meet the requirements herein. The insurance certificates required hereby shall provide that he insurance carrier shall endeavor to provide the certificate holders with at least ten (10) days notice prior to the cancellation, non-renewal or adverse material change in any policy covered thereby. If any policy of Insurance required to be maintained by Contractor herein is cancelled or non-renewed, Contractor shall promptly replace the policy with a substantially similar policy from an insurer with an A.M. Best’s Insurance Rating of A:  VIII or better, and Contract will provide evidence of same to owner.

This Agreement is entered into as of the day and year first written above and is executed in at least three original copies, of which one is to be delivered to the Contractor, one to the Architect for use in the administration of the Contract, and the remainder to the Owner.

CAUTION: You should sign an original AIA document or a licensed reproduction. Originals contain the AIA logo printed in red; licensed reproductions are those produced in accordance with the Instructions to this document.

EXHIBIT C

List of Drawings

New Laboratories & Offices for: MOMENTA, Level Four, 300 Third Street Cambridge, Massachusetts. Construction Set 19 June 2007. Alexandria Real Estate as the Owner, Momenta Pharmaceuticals Inc as the Tenant, FL Caulfield & Sons as the Construction Manager and Olsen Lewis Dioli & Doktor Architect as the Architect.

Architectural:

A1.0, Existing/Demolition Parking Level 1 Plan, Construction Set, 19 June 2007

A1.1, Proposed Plan Parking Level 1 & 2, Construction Set, 19 June 2007

A2.0, Existing Plan, Construction Set, 19 June 2007

A2.1, Proposed Plan, Construction Set, 19 June 2007

A2.2, Reflected Ceiling Plan, Construction Set, 19 June 2007

A2.3, Equipment Plan, Construction Set, 19 June 2007

A2.4, Dimensioned Plan, Construction Set, 19 June 2007

A2.5, Furniture & Cubicles Plan, 19 June 2007

A2.6, Fire Extinguisher Location Plan, Construction Set, 19 June 2007

A5.0, Casework Elevations, Construction Set, 19 June 2007

A6.0, Wall and Door Types, Schedules, Construction Set, 19 June 2007

AF2.1, Proposed Flooring/ Paint Plan and Finish Schedule, Construction Drawings, 27 March 2007

Structural:

S1, (Dated in general notes 25 April 2007)

S2, (Not dated, drawing reflect new generator and fan location)

Fire Alarm:

FA.0, Legend, Detail and Notes, Value Engineering Changes, 8 May 2007

FA.1, Parking Levels One & Two, Partial Plans, Value Engineering Changes, 8 May 2007

FA.2, Fourth Floor Office Plan, Value Engineering Changes, 8 May 2007

Fire Protection:

FP.0,  Legend, Details and Notes, Value Engineering Changes, 8 May 2007

FP.1, Parking Levels One & Two, Partial Plans, Value Engineering Changes, 8 May 2007

FP.2D, Fourth Floor, Demolition Plan,Value Engineering Changes, 8 May 2007

FP.2, Fourth Floor, New York Plan, Value Engineering Changes, 8 May 2007

Plumbing:

P0.1, Legend and Diagrams, Value Engineering Changes, 8 May 2007

P1.1, Parking Level 1 (First Floor), Value Engineering Changes, 8 May 2007

P1.2, Parking Level 1 (Second Floor), Value Engineering Changes, 8 May 2007

P2.1. Office Level 1 Part Plan (Third Floor),Value Engineering Changes, 8 May 2007

P2.2, Office Level 1 Part Plan (Third Floor),Value Engineering Changes, 8 May 2007

P2.3, Office Level 1 Part Plan (Third Floor),Value Engineering Changes, 8 May 2007

P3.1, Office Level II Part Plan (Fourth Floor), Value Engineering Changes, 8 May 2007

P3.2, Office Level II Part Plan (Fourth Floor), Value Engineering Changes, 8 May 2007

P3.3, Office Level II Part Plan (Fourth Floor), Value Engineering Changes, 8 May 2007

P4.1, Roof Plan, Value Engineering Changes, 8 May 2007

P5.1, Part Plan, Value Engineering Changes, 8 May 2007

Mechanical:

H0.1, HVAC Legend & General Notes, Value Engineering Changes, 8 May 2007

H0.2, HVAC Schedules, Value Engineering Changes, 8 May 2007

H0.3, HVAC Details, Value Engineering Changes, 8 May 2007

H0.4, HVAC Details, Value Engineering Changes, 8 May 2007

H1.1. HVAC Parking Level 1 Plan, Value Engineering Changes, 8 May 2007

H1.2, HVAC Fourth Floor Ductwork Plan, Value Engineering Changes, 8 May 2007

H1.3, HVAC Fourth Floor Piping Plan, Value Engineering Changes, 8 May 2007

H1.4, HVAC Roof Plan, Value Engineering Changes, 8 May 2007

Electrical:

E0.1, Legend, Notes and Schedules, Value Engineering Changes, 8 May 2007

E0.2, Power Riser Distribution Diagram, Value Engineering Changes, 8 May 2007

E0.3, Schedules and Details, Value Engineering Changes, 8 May 2007

E0.4, Details, Value Engineering Changes, 8 May 2007

E1.1, First Floor Lighting Part Plans, Value Engineering Changes, 8 May 2007

E1.2, Fourth Floor Lighting Plan, Value Engineering Changes, 8 May 2007

E2.1, First Floor Power Part Plans, Value Engineering Changes, 8 May 2007

E2.2, Fourth Floor Power Plan, Value Engineering Changes, 8 May 2007

E2.3, Roof Level Power Plan, Value Engineering Changes, 8 May 2007

ED1.1, First Floor Demolition Part Plans, Value Engineering Changes, 8 May 2007

TD1.2, Fourth Floor Communications Plan, Value Engineering Changes, 8 May 2007

EXHIBIT D

Copy of Architect Contract

4 October 2006

Mr. Richard Shea

Momenta Pharmaceuticals, Inc.

675 West Kendall Street

Cambridge, Massachusetts 02142

Re: Fee Proposal for Design of New Offices and Laboratories for Momenta, 2^nd Floor, 300 Third Street, Cambridge, Mass

Mr. Shea:

I am pleased to submit this fee proposal for the above described project. This fee proposal covers Schematic Design, Permit Drawings, Construction Drawings, and Construction Observation of the approximately 20,000 sq ft space at 300 Third.

We assume that you will develop a program which would include names of spaces in the project, areas of the individual spaces (or desired dimensions), projected head counts and an equipment matrix which would list all floor standing equipment and any benchtop equipment which might have specific utility requirements such as 208 volt power, RODI water, CO2, etc. We are available to consult with you to assist you in the preparation of the above documents. Should you wish to hire us to prepare the above documents we will do so for the additional fee of $10,000.

We will act as Architect for the above project and will provide all the Basic Services as described, for a fixed fee of $180,700. The fee is divided into the following Phases:

The fee includes normal expenses such as travel to and from the site and your offices, and all prints needed to execute the project (except those to be used for bidding and construction). MEPFP Engineering services only are included (AHA Engineers) in this proposal. We assume that no structural engineering is required as there is already rooftop areas allocated for your air handling equipment. Any

additional consultants for the project will be hired only with your agreement and will be billed to you at their cost.

This fee is based on the assumption that you will work with an experienced BioTech contractor to build the project, such as Linbeck, The Richmond Group, or other similarly capable company.

We will supply all working prints for the project except those used for construction (typically paid for by the contractor). We expect no additional reimbursable expenses for the project.

We will bill you monthly on a basis of percentage completion of the various phases.

Looking forward to working with you towards a successful collaboration on this project, I remain…

STANDARD SCHEDULE OF CHARGES AND CONDITIONS

I. Fees

Work covered by a fixed fee in the Letter of Agreement will be billed monthly on a basis of percentage of completion of the Architect’s work. The fees will not exceed the amount in the Letter Agreement unless an amendment or Change Order is signed by both parties.

II. Consultants

Fees for consultants not included in the Letter of Agreement, will be charged at a multiple of 1.10 times professional service charges. Additional consultants shall be used only when authorized in writing by the Owner.

III. Reimbursable Expenses

Reimbursable Expenses are in addition to compensation for the Architect’s services and include expenses incurred by the Architect and Architect’s employees and consultants directly related to the Project. The following items of direct non-salary expenses will be billed at a multiple of 1 times the actual direct cost.

1.                       authorized out-of-town travel and subsistence,;

2.                       fees paid for securing approval of authorities having jurisdiction over the Project;

3.                       reproductions, plots, standard form documents, postage, handling and delivery of Instruments of Service;

4.                       renderings, models and mock-ups requested by the Owner;

5.                       expense of professional liability insurance dedicated exclusively to this Project or the expense of additional insurance coverage or limits requested by the Owner in excess of that normally carried by the Architect and the Architect’s consultants;

6.                       other similar direct Project-related expenditures, approved in advance by Owner in writing.

IV. Change in Services

Change in Services of the Architect, including services required of the Architect’s consultants, may be accomplished after execution of this Agreement, without invalidating the Agreement, if mutually agreed in writing. The Architect shall notify the Owner prior to providing such services. If the Owner deems that all or a part of such Change in Services is not required, the Owner shall give prompt written notice to the Architect, and the Architect shall have no obligation to provide those services. Except for a change due to the fault of the Architect, Change in Services of the Architect shall entitle the Architect to an adjustment in compensation and to any Reimbursable Expenses.

The following circumstances that affect the Architect’s services for the Project, shall entitle the Architect to an appropriate adjustment in the Architect’s schedule and compensation:

1.                       change in the instructions or approvals given by the Owner that necessitate revisions in Instruments of Service;

2.                       enactment or revision of codes, laws or regulations or official interpretations which necessitate  changes to previously prepared Instruments of Service;

3.                       decisions of the Owner not rendered in a timely manner;

4.                       significant change in the Project including, but not limited to, size, quality, complexity, the Owner’s  schedule or budget, or procurement method;

5.                       failure of performance on the part of the Owner or the Owner’s consultants or contractors;

6.                       preparation for and attendance at a public hearing, a dispute resolution proceeding or a legal  proceeding except where the Architect is party thereto;

The Architect shall be paid at the rate or rates set forth herein for Change in Services:

V. Invoices and Retainers

A.    Where included in the Letter of Agreement, retainers are due with the execution of the Agreement. Invoices will generally be submitted monthly for services performed during the previous month or at the end of phases described in the Letter of Agreement. Payment will be due within 30 days of receipt of the invoice. Interest will be added to accounts in arrears over 30 days.

B.    Unless a maximum sum is agreed upon and incorporated into the Letter of Agreement, the Owner’s obligation for Architect’s services shall be limited to the accrued services performed, consultants, fees and reimbursable expenses to date of invoice.

VI. Insurance and Liability

We are protected by Workers Compensation Insurance, Professional Liability Insurance and by Standard Public Liability Insurance. We will furnish information and Certificates at your request. Our Professional Liability Insurance Limit is $1,000,000. Additional coverage at the Owner’s request is available upon reimbursement to the Architect of increased premium charge.

VII. Ownership and Use of Documents

A.    Drawings, specifications, and other documents produced by the Architect under the Agreement (“Developments”), shall be “works made for hire” and the exclusive property of Owner. Architect shall keep and maintain complete records of all Developments and all work carried out by Architect under the terms of this Agreement. These records shall also be “works made for hire” and the exclusive property of Owner. Architect may keep one copy of these records in its files solely for reference purposes. Architect assigns to Owner all of its right, title and interest in and to any and all Developments. During and after the term of this Agreement, Architect will cooperate fully in obtaining proprietary protection for any and all Developments, all in the name of the Owner and at Owner’s cost and expense, and, without limitation, shall execute and deliver all requested applications, assignments and other documents, and take such other measures as Owner shall reasonably request, in order to perfect and enforce Owner’s rights in any and all Developments. Architect hereby appoints Owner its attorney-in-fact to execute and deliver any such documents on behalf of Architect in the event Architect shall fail to do so.

B.    Architect shall not  use any third party intellectual property or facilities in performing the Services contemplated by this Agreement or engage in any other activities that would result in a third party having an ownership interest in any Developments.

VIII. Confidential Information.

A.    As used in this Agreement, the term “Confidential Information” shall mean any and all proprietary information of Owner, including, without limitation, that pertaining to its technologies, products, intellectual property, finances, operations and/or business, which is disclosed to Architect by Owner, or which Architect learns or observes through the course of performing services hereunder. Architect shall hold in strict confidence all Confidential Information and shall not disclose to any other person any of the Confidential Information.

B.    Limitation on Obligations. The obligations of Architect specified herein shall not apply, and Architect shall have no further obligations, with respect to any Confidential Information to the extent Architect can demonstrate that such Confidential Information:

(1)          is generally known to the public at the time of disclosure or becomes generally known through no wrongful act on the part of Architect;

(2)          is lawfully in Architect’s possession at the time of disclosure other than as a result of a breach of any legal obligation by any party; or

(3)          becomes known to Architect through disclosure by a third party having the legal right to disclose such Confidential Information, provided that such disclosure is made to Architect without any obligation of non-use or non-disclosure.

C. Ownership. Architect agrees that Owner is and shall remain the exclusive owner of the Confidential Information and all patent, copyright, trade secret, trademark and other intellectual property rights therein. No license or conveyance of any such rights to Architect is granted or implied under this Agreement.

D. Return of Confidential Information. Upon the written request of Owner, Architect shall return or destroy (as instructed by Owner), within ten business days of such request, all tangible manifestations of the Confidential Information. Subsequent to any return of the Confidential Information, Architect will continue to be bound by his/her obligations hereunder.

IX. Construction Cost Estimates

Since the Architect has no control over construction cost or contractors’ prices, any construction cost estimates are made on the basis of the Architect’s experience and judgment as a design professional, but the Architect cannot and does not warrant or guarantee that contractors’ proposals, bids or costs will not vary from the Architect’s estimates.

X. Owner’s Responsibilities

A.    The Owner shall furnish such legal, accounting, and insurance counseling services as may be required for the project and shall provide the Architect with all existing information relating to the project which the Architect may request. If the Owner becomes aware of any fault or default in the project or the Architect’s services, the Owner shall promptly notify the Architect. The Owner shall furnish required information or services as expeditiously as necessary for the orderly performance of the work.

XI. Architect’s Role During Construction

If this Agreement provides for construction phase services by the Architect, the Architect shall visit the site at intervals appropriate to the stage of construction, to become generally familiar with the progress and quality of the work and to determine, in general, if the work is proceeding in accordance with the drawings, specifications, and other contract documents. On the basis of the on-site observations as an Architect, the Architect shall endeavor to guard the Owner against defects and deficiencies in the work of the Contractor. However, it is understood that the Contractor, not  the Architect, is responsible for the construction of the project, and that the Architect is not responsible for the acts or omissions of any contractor or subcontractor, for safety programs or enforcement, or for construction means, methods, techniques, sequences, and procedures employed by the Contractor.

XII. Termination and Suspension of Service

A.    This Letter of Agreement may be terminated by either party in case of substantial breach by the other, upon fifteen days prior written notice, provided that the breaching party has not cured such breach within the aforementioned fifteen days. In addition, Owner may terminate this Agreement at any time upon 30 days prior written notice. In the event of termination for reasons other than the Architect’s breach, the Architect shall be compensated for all services performed up to the termination date, together with reimbursable expenses then due.

B.    In the event the Architect’s services are terminated prior to completion of construction of the project: the Architect shall not be responsible for any changes made by others in any documents furnished by the Architect, hereunder, for any components of the Project for which shop drawings or other submissions are required, for the failure of any construction contractor to construct the Project or any portion thereof in accordance with documents furnished by the Architect, or for any errors or omissions in documents furnished by the Architect which could have been discovered and corrected by the Architect had it been engaged for subsequent phases of work on the Project.

C.    Except for damages resulting from a breach of confidentiality obligations hereunder, the Architect and the Owner waive consequential damages for claims, disputes or other matters in question arising

out of or relating to this Agreement. This mutual waiver is applicable, without limitation, to all consequential damages due to either party’s termination in accordance with Section

XIII. Promotional and Professional Materials

The Architect shall have the right to include photographic or artistic representations of the design of the Project among the Architect’s promotional and professional materials. The Architect shall be given reasonable access to the completed Project to make such representations. However, the Architect’s materials shall not include the Owner’s confidential or proprietary information if the Owner has previously advised the Architect in writing of the specific information considered by the Owner to be confidential or proprietary. The Owner shall provide professional credit for the Architect in the Owner’s promotional materials for the Project.

XIV. Basic Agreement

This Agreement represents the complete integrated agreement between the parties, supersedes all prior agreements, may be amended only in writing, and is binding upon the parties, their successors, assigns, and legal representatives.

19 August 2007

Mr. Richard Shea

Momenta Pharmaceuticals, Inc.

675 West Kendall Street

Cambridge, Massachusetts 02142

Re: Request for Fee Increase – Design of New Offices and Laboratories for Momenta, 2^nd Floor, 300 Third Street, Cambridge, Mass

Mr. Shea:

I apologize for sending this along to you now ... I have had this on my list of things to do for a long time. At firtst, it was actually doing the work described in this letter, then, it was dealing with the change to Alnylam’s occupancy of the space and also, a few hundred other things ...

I request a fee increase in the amount of $33,000.00. This increase is requested due to the additional work required when we are asked to make various changes to reduce the cost of the project after we had completed our Construction Documents. This caused the most work to be done by AHA Engineers as the changes affected more of their work (and drawings) than mine. Also, AHA has included in their request, an item which lists a fee amount covering additional site visits which were not a part of their original fee proposal as discussed with John Shearns.

The amounts requested are:

Should this letter meet your approval, please sign and return a copy to me.

Call or email me if you have any question regarding this request.

EXHIBIT E-1

List of Equipment

EXHIBIT E-2

Copies of Purchase Orders

EXHIBIT F

Copies of Approvals

EXHIBIT G

Detail Breakdown of Purchase Price

(1) Does not include $14,527.23 paid by Momenta to Archemix as reimbursement for repair of damaged sprinkler valves.  As described in the last recital of the Purchase Agreement, such amount is not being reimbursed by Alnylam.

(2) Does not include reimbursement of Alnylam’s share of “Sublandlord’s Costs” paid by Momenta pursuant to Section 3.6 of the Purchase Agreement.

EXHIBIT H-1

[Form of Assignment, Assumption and Consent Agreement, and First Amendment to Sublease]

ASSIGNMENT, ASSUMPTION AND CONSENT AGREEMENT; AND

FIRST AMENDMENT TO SUBLEASE

ASSIGNMENT, ASSUMPTION AND CONSENT AGREEMENT; AND FIRST AMENDMENT TO SUBLEASE (this “Agreement”) dated as of October     , 2007 by and among Momenta Pharmaceuticals, Inc., a Delaware corporation (“Assignor”), Alnylam Pharmaceuticals, Inc., a Delaware corporation (“Assignee”), and Archemix Corp., a Delaware corporation (“Sublandlord”).

RECITALS

A.                                   ARE-MA Region No. 28, LLC, a Delaware limited liability company and successor-in-interest to Three Hundred Third Street L.L.C., (“Overlandlord” or “Landlord”) is the landlord under that certain Lease dated April 11, 2005, as amended by that certain First Amendment to Lease dated July 9, 2006 (“First Amendment to Lease”) and that certain Second Amendment to Lease dated October     , 2007 (“Second Amendment to Lease”), (collectively, the “Overlease”), pursuant to which Overlease, Sublandlord leases approximately 67,543 rentable square feet of space in that certain building commonly known as 300 Third Street, Cambridge, Massachusetts (“Building”).

B.                                     Assignor is the subtenant under that certain Sublease dated September 8, 2006, as consented to by Overlandlord pursuant to that certain Consent to Sublease dated October 23, 2006 between Overlandlord, Sublandlord and Assignor (“Sublease Consent”) (collectively, said sublease, as affected by the Sublease Consent is referred to herein as the “Sublease”), wherein Sublandlord subleases to Assignor the Subleased Premises consisting of approximately 22,364 rentable square feet located on a portion of the second floor in the Building, which Subleased Premises are more particularly described in the Sublease (the “Subleased Premises”). A true, complete and correct copy of the Sublease is attached hereto as Exhibit A.

C.                                     Assignor desires to assign its rights under the Sublease to Assignee, and Assignee desires to accept such assignment and to assume the performance of Assignor’s obligations thereunder, upon the terms and conditions set forth herein.

D.                                    Section 12 of the Sublease provides that the Sublease may not be assigned without the written consent of Sublandlord and Overlandlord.

E.                                      Sublandlord is willing to consent to the assignment of the Sublease from Assignor to Assignee upon the terms and conditions set forth herein.

NOW, THEREFORE, in consideration of One Dollar ($1.00) and other good and valuable consideration, paid by each of the parties hereto to the other, the receipt and sufficiency of which is hereby acknowledged, and in further consideration of the provisions herein, the parties hereto agree as follows:

1.                                       Effective Date. The “Effective Date” of this Agreement shall be the date upon which all of the following shall have occurred:

(a)                                  Each of Assignor, Assignee, Sublandlord and Landlord shall have unconditionally received a fully executed counterpart of this Agreement;

(b)                                 Overlandlord shall have provided (i) a fully executed Second Amendment to the Overlease to Sublandlord in a form acceptable to Sublandlord, and (ii) its fully executed written consent, to the parties hereto (in a form acceptable to the parties hereto), to the assignment and assumption referenced in Section 2(a) hereof, the amendment of Sublease provisions referenced in Section 9 hereof, and the Subtenant’s Work plans in accordance with the terms of the Overlease and Sublease;

(c)                                  Sublandlord shall have unconditionally received from Assignee the Security Deposit required of the subtenant under the Sublease pursuant to Section 5 of the Sublease, as amended herein; and

(d)                                 the conditions set forth in Section 2 of that certain Consent to Assignment of Sublease dated as of October     , 2007 (“Landlord’s Assignment Consent”) have been completed.

It shall be a condition precedent to the occurrence of the Effective Date that there then exist neither an Event of Default under the Sublease, nor any state of facts which, with the giving of notice or passage of time or both, would constitute an Event of Default under the Sublease. If for any reason the Effective Date shall not have occurred on or before October 31, 2007, any party hereto shall have the right to terminate this Agreement by written notice to the other parties hereto, provided however, that in the event of such termination, (i) Assignor’s obligation to pay Sublandlord the Sublandlord’s Costs (as defined hereinafter) and (ii) Assignor’s and Assignee’s obligations set forth in Section 11 of this Agreement shall survive the termination of this Agreement. Promptly after the occurrence of the Effective Date, Sublandlord, Assignor and Assignee shall confirm the Effective Date in writing.

2.                                       Assignment and Assumption; Indemnities. Effective as of the Effective Date:

(a)                                  Assignor assigns and transfers to Assignee all of its right, title and interest as subtenant under the Sublease. Effective as of the Effective Date, Assignee (i) accepts such assignment, assumes the performance of all of the obligations as subtenant under the Sublease and agrees to be directly bound and fully liable to Sublandlord for, and to duly observe and comply with, all of the terms, covenants, agreements, provisions, obligations and conditions on the part of the subtenant and the Assignee to be performed or observed under the Sublease and this Agreement, respectively, and (ii) agrees for the benefit of Sublandlord and Overlandlord that Sublandlord and Overlandlord shall have the right to enforce against Assignee all of the Assignor’s obligations, liabilities, and duties under the Sublease to be performed by Assignee as fully and completely as if Assignee had originally executed the Sublease as the subtenant thereunder;

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(b)                                 Assignor covenants and agrees to indemnify and hold harmless Assignee and Sublandlord from and against all costs, expenses, claims and losses, including, without limitation, reasonable attorneys’ fees, arising out of or in connection with any defaults in Assignor’s performance of its obligations as subtenant under the Sublease, which defaults occurred or arose out of the acts or failure to act of Assignor prior to the Effective Date;

(c)                                  Assignee covenants and agrees to indemnify and hold harmless Sublandlord and Assignor from and against all costs, expenses, claims and losses, including, without limitation, reasonable attorneys’ fees, arising out of or in connection with any defaults in Assignee’s performance of its obligations as subtenant under the Sublease, including, but not limited to, those defaults which occur or arise out of the acts or failure to act of Assignee from and after the Effective Date; and

(d)                                 On the Effective Date, (i) Assignor shall deliver the Subleased Premises to Assignee vacant, as-is-where-is and subject to the construction work in process associated with Subtenant’s Work (as defined in the Sublease) and Equipment (as defined in Section 10 hereof), and (ii) upon such delivery, Assignee automatically is deemed to accept possession of the Subleased Premises in such condition.

3.                                       Assignment Subject to Lease. The assignment in Section 2(a) above shall be subject at all times to the Sublease and to all of the provisions, covenants, agreements, terms and conditions of the Sublease and this Agreement, and Assignee shall not do or permit anything to be done in connection with Assignee’s use and occupancy of the Subleased Premises which would violate any of said provisions, covenants, agreements, terms and conditions.

4.                                       Consent. Effective as of the Effective Date, Sublandlord (i) consents to the assignment and assumption set forth in Section 2(a) above, subject to the covenants, agreements, terms, provisions, and conditions contained in the Sublease and subject to and in reliance upon, the representations, warranties, covenants, agreements, terms, provisions and conditions, contained in this Agreement and in Landlord’s Assignment Consent, and (ii) shall, on the next business day following the Effective Date, return to Silicon Valley Bank the Silicon Valley Bank letter of credit no. SVB-8800061917 in the amount of $2,907,320.00, request that Silicon Valley Bank cancel said letter of credit no. SVB-8800061917, and provide a copy of such request to Assignor. Sublandlord’s consent shall be deemed limited solely to this assignment and assumption, and Sublandlord reserves the right to consent or withhold consent, and all other rights as set forth in the Sublease, with respect to any other matters.

5.                                       Representations, Warranties and Acknowledgments.

(a)                                  Assignor and Assignee represent, warrant and acknowledge to Sublandlord that:

(i)                                     no money or other consideration has been or will be paid or given to Assignor by Assignee for this assignment or corresponding right to use or occupy the Subleased Premises other than as set forth in this Agreement, in Section 2.3 of that

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certain Purchase Agreement dated as of the date hereof by and between Assignor and Assignee (“Purchase Agreement”), and as set forth in Section 2.1 of the Purchase Agreement regarding potential adjustments to rent under the Sublease (including, but not limited to, those adjustments arising from recalculation of operating expenses or real estate taxes thereunder) for the time period set forth in item 1 of Exhibit G to the Purchase Agreement;

(ii)                                  As to Sublandlord, (A) this Agreement embodies the complete and entire agreement between Assignor and Assignee with respect to the assignment and assumption of the Sublease and (B) further, in the event of any conflict or inconsistency between the terms, covenants or conditions of this Agreement, and the terms, covenants or conditions of any other agreement between Assignor and Assignee, the terms, covenants and conditions of this Agreement shall control;

(iii)                               Sublandlord’s Work (as defined in the Sublease) and any other improvements required to be made by Sublandlord under the Sublease have been satisfactorily completed; as of the Effective Date, none of the Subtenant Allowance (as defined in the Sublease) has been requested by Assignor or paid by Sublandlord to Assignor (and Assignor and Assignee, respectively, have no claims arising therefrom or in connection therewith), the rent commencement date under the Sublease occurred on March 10, 2007, and there are no concessions, inducements or work to which the subtenant under the Sublease is entitled other than the remaining unpaid portion of the Subtenant Allowance payable by Sublandlord to Assignee pursuant to and in accordance with the terms of the Sublease;

(iv)                              to the best of their knowledge, no default on the part of Sublandlord exists under the Sublease, and there are no rights of off-set, counterclaims, or credits against rent or other charges under the Sublease;

(v)                                 all of the representations and warranties made by Assignor as subtenant under the Sublease are valid and enforceable as of the Effective Date of this Agreement (which representations and warranties shall hereby be deemed remade by Assignee as of the Effective Date);

(vi)                              notwithstanding any representations by Sublandlord or provisions to the contrary in the Sublease or this Agreement, the Subleased Premises (including, but not limited to, the Existing P-1 Subleased Premises and Additional P-1 Sublease Premises (which are defined hereinafter in this Agreement)), when delivered by Assignor (or by Sublandlord, as the case may be for part of the Existing P-1 Subleased Premises and/or Additional P-1 Sublease Premises) to Assignee, as of the Effective Date, are delivered by Assignor (or by Sublandlord, as the case may be for part of the Existing P-1 Subleased Premises and/or Additional P-1 Sublease Premises) and accepted by Assignee in their as-is-where-is condition and Sublandlord shall not be responsible or liable in any way to any party for the condition, progress or state or quality of construction of Subtenant’s Work or any other work to or condition of the Subleased Premises; and

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(vii)                           there are no rights of off-set, counterclaims, or credits against rent or other charges under the Sublease based upon facts, circumstances, occurrences, or events existing prior to or on the Effective Date.

(b)                                 Assignor hereby represents and warrants to Assignee, as of the date hereof (which representations and warranties shall be deemed remade as of the Effective Date and shall survive the Effective Date) as follows, and agrees to indemnify and save Assignee harmless from and against any and all suits, actions, damages, reasonable costs and expenses (including, without limitation, reasonable attorneys’ fees and other charges) which Assignee may sustain by reason of Assignor’s breach of any of such representations and warranties:

(i)                                     The Sublease (except as (A) modified hereby and (B) set forth in this Agreement) is a complete statement of the agreement between the parties hereto with respect to the subletting of the Subleased Premises. A copy of the Sublease is attached hereto as Exhibit A.

(ii)                                  The Sublease is presently in full force and effect as a valid and binding obligation according to its terms.

(iii)                               Assignor has not assigned, mortgaged, pledged, encumbered or otherwise transferred or sublet, in whole or in part, its subleasehold estate with respect to the Subleased Premises.

(iv)                              The term of the Sublease has commenced and the full rental is now accruing and payable thereunder. Fixed Rent under the Sublease has been paid through October 31, 2007.

(v)                                 Assignor has accepted possession of the Subleased Premises, and any improvements required by the terms of the Sublease to be made by Sublandlord have been completed to Assignor’s satisfaction.

(vi)                              None of the Subtenant Allowance (as defined in the Sublease) has been requested by Assignor or paid by Sublandlord to Assignor (and Assignor has no claims arising therefrom or in connection therewith).

(vii)                           As of the Effective Date, Assignor is not in default under the terms of the Sublease and has no charge, lien or claim (under the Sublease or otherwise) against rents or other charges due or to become due to Sublandlord thereunder. To Assignor’s knowledge, Sublandlord is not in default or breach of its obligations under the Sublease and Assignor has not sent or received any notice to the contrary.

(c)                                  Sublandlord hereby represents and warrants to Assignee and Assignor, as follows:

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(i)                                     The Sublease (except as modified by this Agreement and Landlord’s Assignment Consent) is unmodified and in full force and effect as of the date hereof.

(ii)                                  Fixed Rent and Additional Rent (subject to possible adjustments to and recalculation thereof pursuant to the terms of the Sublease and Overlease) have been paid through October 31, 2007 and, as of the date hereof, no other Additional Rent is due from Assignor under the Sublease.

(iii)                               To Sublandlord’s knowledge, neither Sublandlord nor Assignor is in default under the Sublease past applicable notice and cure periods, and Sublandlord has not sent or received any notice to the contrary.

(iv)                              Sublandlord has not assigned, mortgaged, pledged, encumbered or otherwise transferred or sublet, in whole or in part its leasehold estate with respect to the Subleased Premises, except as set forth in the Sublease.

6(a).                         Partial Release of Assignor. This Agreement shall not operate to waive, modify (except as specifically set forth in Section 9 hereof), impair, release or in any manner affect any of the covenants, agreements, terms, provisions, obligations or conditions contained in the Sublease or to waive any breach thereof, or any rights of Sublandlord against any person, firm, association or corporation liable or responsible for the performance thereof. All terms, covenants, agreements, provisions and conditions of the Sublease are hereby ratified (as modified in Section 9 hereof) and declared by Assignee to be in full force and effect. As of the Effective Date, Assignee hereby unconditionally affirms its primary, direct and ongoing liability to Sublandlord for the performance of all obligations to be performed by the subtenant under the Sublease, including, without limitation, the obligations to pay Fixed Rent, Additional Rent and all other charges in the full amount, in the manner and at the times provided for in the Sublease. Sublandlord hereby releases Assignor from its obligations under the Sublease arising on and after the Effective Date of this Agreement. Assignor, however, agrees that nothing herein shall release or cause to be released Assignor from any of its obligations under the Sublease arising prior to the Effective Date of this Agreement, and Assignor shall remain fully liable therefor.

6(b).                        Excess Income. Only to the extent that Landlord expressly agrees and acknowledges in writing in Section 3(d) of the Landlord’s Assignment Consent that the consideration paid by Assignee to Assignor in connection with this transaction, is not considered as a sum or value given in consideration of this transaction for purposes of determining Excess Income (as defined in the Overlease) under the Overlease, Sublandlord also hereby agrees and acknowledges the same for purposes of determining Excess Income under the Sublease solely as to this transaction. Sublandlord is in no way making any representations, agreements or acknowledgements about what consideration is or is not considered as Excess Income as to any future transactions.

7.                                       Further Assignment or Subletting. Assignor and Assignee hereby agree that the terms, conditions, restrictions and prohibitions set forth in the Sublease regarding subletting and

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assignment (as modified hereby), including, without limitation, Section 12 of the Sublease, shall, notwithstanding this Agreement, (i) continue to be binding upon Assignor and Assignee with respect to all future assignments and transfers of the Sublease and all future sublettings of the Subleased Premises, and (ii) apply to Assignee with the same effect as if Assignee had been the original subtenant named in the Sublease. This Agreement shall not be construed either as a consent by Overlandlord, Sublandlord and/or Assignor to, or as permitting, any other or further assignment or transfer of the Sublease, whether in whole or in part, or any further subletting of the Subleased Premises or any part thereof, or as a waiver of the restrictions and prohibitions set forth in the Sublease regarding subletting and assignment.

8.                                       Remedies for Default. In the event (i) of any default by Assignor or Assignee in the full performance and observance of any of their respective obligations hereunder or (ii) any representation or warranty of Assignor and Assignee made herein is false or misleading in any material respect, either of such event may, at Sublandlord’s option, be deemed an Event of Default under the Sublease, and Sublandlord shall have the right to and may pursue all of the rights, powers and remedies provided for in the Sublease or at law or in equity or by statute or otherwise with respect to defaults, provided however, that if and to the extent the Sublease provides for notice of and/or an opportunity to cure the failure to perform any such obligation, such event shall only be deemed to be an Event of Default under the Sublease if it is not cured after the giving of any such notice to the party who failed to perform (with a copy of such notice to the other party) and the expiration of any such cure period.

9.                                       Amendment of Sublease. Effective as of the Effective Date, the Sublease shall be deemed amended as follows:

(a)                                  Surrender of Return Space and Addition of P-1 Subleased Premises.

(i)  Surrender of Return Space and P-1 Subleased Premises.  The following language shall hereby be added at the end of the first paragraph of Recital Section B of the Sublease and incorporated directly into the Sublease as a part thereof:

“Subtenant hereby returns and surrenders to Sublandlord the “Return Space” consisting of approximately 415 rentable square feet of space on the second floor of the Building, as such Return Space is more particularly described on Exhibit B-1 to the Sublease attached hereto and incorporated herein by reference. Said Return Space shall no longer be deemed a part of the Subleased Premises under the Sublease and Subtenant hereby acknowledges that, with Subtenant’s express consent, pursuant to the Second Amendment to Lease, Sublandlord surrendered said Return Space to Landlord.

Subtenant further desires to sublease from Sublandlord and Sublandlord desires to sublease to Subtenant three hundred and forty-three (343) rentable square feet of space located on the P-1 level of the Building, plus an additional seventy-two (72) rentable square feet of space located on the P-1 level of the Building (collectively, yielding 415 rentable square feet of space referred to herein as the “Existing P-1

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Subleased Premises”) and an additional ninety-two (92) rentable square feet of space located on the P-1 level of the Building (“Additional P-1 Sublease Premises”), both of which are more particularly depicted on Exhibit B-1 to the Sublease attached hereto and incorporated herein by reference. The Existing P-1 Subleased Premises and Additional P-1 Sublease Premises shall henceforth be deemed to be included as part of the “Subleased Premises” as referenced throughout this Agreement (where applicable) and throughout the Sublease. By way of clarification, (i) after accounting for the surrender of the Return Space, the Existing P-1 Subleased Premises are included in the 22,364 rentable square feet of the subleased premises referenced in this Recital B of the Sublease, and (ii) the net effect of the foregoing surrender of the Return Space and addition of the Existing P-1 Subleased Premises and Additional P-1 Sublease Premises yields, (A) an additional 92 rentable square feet of space added to the Subleased Premises and rent and all other charges under the Sublease shall be adjusted proportionately as contemplated under the Sublease, and (B) the total rentable square footage of the Subleased Premises consisting of approximately 22,456 rentable square feet of space.”

(ii)  Subtenant Allowance Calculation Not To Include Additional P-1 Sublease Premises. Notwithstanding anything to the contrary in the Overlease, Sublease (including, but not limited to, Section B of Exhibit C to the Sublease), this Agreement or any other document, the amount of the Subtenant Allowance (as defined in the Sublease) shall not increase to include and shall not reflect inclusion of the addition of the Additional P-1 Sublease Premises in the Subleased Premises. The rentable square footage area of the Additional P-1 Sublease Premises shall not be included in calculating the dollar amount of the Subtenant Allowance.

(b)                                 Expiration Date. The next to last sentence of Section 2(a) of the Sublease shall hereby be deleted and replaced with the following:

“The Term of this Sublease shall end on September 30, 2011 (the “Expiration Date”), as it may be extended hereunder, or shall end on such earlier date upon which such term may expire or be terminated pursuant to the provisions hereof or pursuant to law.”

(c)                                  Extended Term. The first sentence of Section 2(b) of the Sublease shall hereby be deleted and replaced with the following:

“Provided that, at the time Subtenant elects to exercise the option herein granted, (i) this Sublease is in full force and effect, (ii) Subtenant is not in default beyond any applicable notice and grace period hereunder, and (iii) Subtenant or an Affiliated Transferee (as defined in Section 16.B of the Overlease) is occupying all of the Subleased Premises, Subtenant shall have the option, upon written notice to Sublandlord (“Subtenant’s Extension Notice”) given not less then twelve (12) months prior to the expiration of the Expiration Date, to extend the Term of this Sublease for an additional three (3) year and seven (7) month period (the “Extended Term”) expiring on April 30, 2015, subject to

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Sublandlord’s Termination Option and Subtenant’s Termination Option (as such terms are hereinafter defined).”

(d)                                 Sublandlord’s Termination Option. Section 2(c-ii) of the Sublease is hereby deleted and replaced with the following:

“where Subtenant has delivered to Sublandlord Subtenant’s Extension Notice as hereinabove provided, and Sublandlord expressly accepts said extension in writing delivered to Subtenant within thirty (30) days after Sublandlord receives Subtenant’s Extension Notice, Sublandlord shall subsequently have the right to terminate the Sublease effective as of the date specified in Sublandlord’s subsequent notice to Subtenant (“Sublandlord’s Early Termination Date”), provided, however, that Sublandlord’s Early Termination Date shall be not less than nine (9) months following the date of such subsequent termination notice by Sublandlord to Subtenant.”

(e)                                  Early Termination. Section 2(e) of the Sublease shall hereby be deleted and replaced with the following:

“Notwithstanding anything to the contrary in Section 2 of the Sublease and without limiting Sublandlord’s rights set forth in Section 9(m) of this Agreement, in no event shall the exercise of Subtenant’s Termination Option or Sublandlord’s Termination Option cause the Sublease to terminate prior to September 30, 2011.”

(f)                                    Failure to Respond to Subtenant Extension Notice. The following sentence shall hereby be added to the Sublease as Section 2(f):

“ (f)                           Notwithstanding anything to the contrary in this Sublease, in the event that Sublandlord fails to expressly, in writing, respond to, reject, or accept Subtenant’s Extension Notice within thirty (30) days of Sublandlord’s receipt of Subtenant’s Extension Notice, Sublandlord shall automatically be deemed to have rejected Subtenant’s Extension Notice and (i) the Sublease shall expire on the Expiration Date, (ii) all rent payable under this Sublease shall be paid and apportioned as of the Expiration Date, (iii) neither party shall have any rights, estates, liabilities or obligations under this Sublease for the period accruing after the Expiration Date, except those which are incurred, have accrued or relate to the period prior to the Expiration Date, and (iv) Subtenant shall surrender and vacate the entire Subleased Premises and deliver possession thereof to Sublandlord on or before the Expiration Date in the condition required under both this Sublease and the Overlease.”

(g)                                 Security Deposit. The first sentence of Section 5(a) of the Sublease is hereby deleted and replaced with the following:

“To secure the full and faithful performance by Subtenant of all the terms, provisions, conditions, covenants and obligations (including, without limitation, the payment of rent) on Subtenant’s part to be performed hereunder, on or before the Commencement Date

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hereof, Subtenant shall deliver to Sublandlord a security deposit (“Security Deposit”) in the amount of Eight Hundred Thirty-Eight Thousand Six Hundred Thirty-Four Dollars ($838,634.00) in either (i) cash or (ii) an unconditional, clean irrevocable “evergreen” letter of credit, payable on sight, in form and substance satisfactory to Sublandlord and otherwise in accordance with the requirements of Article 23 of the Overlease.”

(h)                                 Security Deposit Reductions.

(i)                                     As of the Effective Date, Section 5(h) of the Sublease shall henceforth be deleted in its entirety.

(ii)                                  To the extent that the security deposit set forth in that certain lease dated as of September 26, 2003 by and between Overlandlord, as successor-in-interest to Cornerstone Real Estate Advisors, Inc., and Assignee of other space located in the Building (“Assignee’s Other Lease”) is reduced on or after the Effective Date, the Security Deposit required pursuant to this Sublease, as assigned to and assumed by Assignee, shall be reduced pro rata per rentable square foot reduction in the security deposit required under Assignee’s Other Lease, provided however, that the Security Deposit hereunder shall in no event be reduced below the amount of six (6) months’ Fixed Rent under this Sublease.

(i)                                     Condition of Subleased Premises. The second to last sentence of Section 7(a) of the Sublease is hereby deleted in its entirety.

(j)                                     Subtenant Notice Address. Section 17(b) of the Sublease shall hereby be deleted and replaced with the following:

“If intended for Subtenant, to:

Alnylam Pharmaceuticals, Inc.

300 Third Street

Cambridge, MA 02142

Attn: Philip T. Chase, Esq., General Counsel,

and to:

Joseph L. Faber, Esq.

Faber Daeufer & Rosenberg PC.

950 Winter Street

Waltham, MA 02451”

(k)                                  Surrender of Subleased Premises. The following paragraph shall be added to the end of Section 18 of the Sublease:

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“Without limiting or affecting Sublandlord’s rights and Subtenant’s obligations set forth in the foregoing paragraph, upon the expiration, or pursuant to the terms of the Sublease, the earlier termination of the Sublease or recapture of any part or all of the Subleased Premises (including, but not limited to, the Existing P-1 Subleased Premises and Additional P-1 Sublease Premises), Sublandlord shall have the right, to require Subtenant (to the extent that Landlord so requires), at Subtenant’s sole expense, to (i) remove any alterations or additions made (by the current Subtenant or by any predecessor subtenant) to the Subleased Premises (including, but not limited to, the Existing P-1 Subleased Premises and Additional P-1 Sublease Premises) or any part thereof, and (ii) reconstruct, to their former location and condition (before the Commencement Date of the Sublease), any demising walls, floors, ceilings, and access points formerly separating the Existing P-1 Subleased Premises and/or Additional P-1 Sublease Premises from the adjacent areas, horizontally and/or vertically.”

(l)                                     Subtenant’s Construction Representative. The second paragraph of Section IV(A) of Exhibit C to the Sublease shall be deleted and replaced with the following:

“Subtenant’s Construction Representative: Richard P. Shea or any replacement designated in writing by Subtenant; Notwithstanding the foregoing, as of the “Effective Date” under that certain ASSIGNMENT, ASSUMPTION AND CONSENT AGREEMENT; AND FIRST AMENDMENT TO SUBLEASE dated October ____, 2007 between Sublandlord, Subtenant and Alnylam Pharmaceuticals, Inc., Subtenant’s Construction Representative shall be John Palmieri or any replacement designated in writing by Subtenant.”

(m)                               Overlease Termination. Notwithstanding anything to the contrary in the Sublease (as amended), including Section 2 of the Sublease, Subtenant hereby acknowledges and recognizes (i) Sublandlord’s right, pursuant to the terms of the Overlease, to terminate the Overlease prior to the Overlease Expiration Date, and (ii) Sublandlord shall have no liability of any kind to Subtenant or any successor arising from or in connection with the exercise, pursuant to the terms of the Overlease, of Sublandlord’s early termination right under the Overlease.

(n)                                 Assignee as Subtenant. From and after the Effective Date of this Agreement, all references to the “Subtenant” in the Sublease shall be deemed to mean Assignee.

10.                                 Equipment. Assignor hereby agrees not to remove the furniture, furnishings, fixtures, equipment and personal property located in the Subleased Premises, as described on Exhibit B hereto (the “Equipment”), but rather to transfer such Equipment to Assignee, subject to and except for any rights of Overlandlord and/or Sublandlord to said Equipment (i) under the Overlease and Sublease and/or (ii) to the extent said Equipment constitutes leasehold fixtures. Assignee shall accept the Equipment on the Effective Date in its “as is” and “where is” condition, subject to reasonable wear and tear, without any representation or warranty whatsoever by Sublandlord or Assignor, oral or written, express or implied (including, without limitation, any representation or warranty with respect to suitability or fitness for any particular use or purpose).

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11.                                 Brokerage; Fees.

(a)                                  Assignor represents and warrants to Sublandlord that Assignor has dealt with no broker, finder or like agent in connection with this transaction, except the Assignee Broker (as more particularly described in the next succeeding section) and that Assignee shall be solely and completely responsible for payment of any fees, commissions or other costs or expenses to the Assignee Broker. In the event any claim is made against Sublandlord relative to dealings by Assignor with any broker, finder or like agent in connection with this transaction (including, but not limited to, by the Assignee Broker), Assignor shall defend the claim against Sublandlord with counsel of Assignor’s selection first reasonably approved by Sublandlord and save harmless and indemnify Sublandlord on account of loss, cost or damage which may arise by reason of such claim.

(b)                                 Assignee represents and warrants to Sublandlord that Assignee has dealt with no broker, finder or like agent in connection with this transaction, except for Richards Barry Joyce and Partners (“Assignee Broker”), and that Assignee shall be solely and completely responsible for payment of any fees, commissions or other costs or expenses to Assignee’s Broker. In the event any claim is made against Sublandlord relative to dealings by Assignee with any broker, finder or like agent in connection with this transaction (including, but not limited to, by the Assignee Broker), Assignee shall defend the claim against Sublandlord with counsel of Assignee’s selection first reasonably approved by Sublandlord and save harmless and indemnify Sublandlord on account of loss, cost or damage which may arise by reason of such claim.

(c)                                  As between Assignor and Assignee only, Assignor represents and warrants to Assignee that Assignor shall reimburse Assignee, upon written demand therefor, for one-half (1/2) of the amount of any fees, commissions or other costs or expenses payable by Assignee to Assignee’s Broker.

12.                                 Miscellaneous.

(a)                                  Successors and Assigns. The terms and provisions of this Agreement shall bind and inure to the benefit of the parties hereto and their respective successors and assigns.

(b)                                 Captions. The captions contained in this Agreement are for convenience only and shall in no way define, limit or extend the scope or intent of this Agreement, nor shall such captions affect the construction hereof.

(c)                                  Counterparts. This Agreement may be executed in several counterparts, each of which shall be deemed an original but all of which shall constitute one and the same agreement.

(d)                                 Authority. Each party hereto represents and warrants that it has full right, power and authority to enter into this Agreement and that the person executing this Agreement on behalf of such party is duly authorized to do so.

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(e)                                  Capitalized Terms. All capitalized terms and words used in this instrument shall have the same meaning as set forth in the Sublease unless a contrary meaning is expressly set forth herein.

(f)                                    Notices. Any notices or other communications given or required to be given under this Agreement shall be effective only if in writing and delivered in the manner set forth in the Sublease, addressed, if to Sublandlord, at the address set forth in the Sublease or at such other address for such purpose designated by notice in accordance with the provisions of the Sublease, if to Assignor, to Richard P. Shea, CFO, Momenta Pharmaceuticals, Inc., 675 W. Kendall Street, Cambridge, MA 02142, with a copy to Momenta Pharmaceuticals, Inc., Attention: General Counsel, 675 W. Kendall Street, Cambridge, MA 02142, and to Jonathan E. Book, Esq., Foley Hoag LLP, 155 Seaport Boulevard, Boston, MA 02210, or at such other address for such purpose designated by notice in accordance with the provisions of the Sublease, and if to Assignee, at Philip T. Chase, Esq., General Counsel, Alnylam Pharmaceuticals, Inc., 300 Third Street, Cambridge, MA 02142, with a copy to Joseph L. Faber, Esq., Faber Daeufer & Rosenberg PC., 950 Winter Street, Waltham, MA 02451 until the Effective Date and thereafter at the Subleased Premises or at such other address for such purpose designated by notice in accordance with the provisions of the Sublease.

(g)                                 Sublandlord’s Costs. Assignor shall be liable to reimburse Sublandlord on demand for any costs incurred by Sublandlord in connection with the assignment and this Agreement, including, without limitation, the costs of making investigations as to the acceptability of Assignee, legal costs incurred in connection with the preparation of this Agreement and review of or work on any related agreements, architect’s fees, engineering costs, or related costs in connection with review and approval of any construction work performed or to be performed to the Subleased Premises, and any costs passed through to Sublandlord by Overlandlord in connection with any of the foregoing or as passed through to Sublandlord pursuant to the terms of the Overlease (collectively, “Sublandlord’s Costs”). As between Assignor and Assignee only, the percentage reimbursement of Sublandlord’s Costs for which Assignee is responsible to reimburse Assignor shall be as set forth in the Purchase Agreement.

(h)                                 Remedies Cumulative. Each right and remedy of Sublandlord provided for in this Agreement or in the Sublease shall be cumulative and shall be in addition to every other right and remedy provided for herein and therein or now or hereafter existing at law or in equity or by statute or otherwise, and the exercise by Sublandlord of any one or more of the rights or remedies so provided for or existing shall not preclude the simultaneous or subsequent exercise by Sublandlord of any or all other rights or remedies so provided for or so existing.

(i)                                     Sublandlord’s Liability. Sublandlord’s liability under this Agreement shall be limited to the same extent Sublandlord’s liability is limited under the Sublease.

(j)                                     Severability. If any one or more of the provisions contained in this Agreement shall be invalid, illegal or unenforceable in any respect, the validity, legality and enforceability of the remaining provisions contained herein shall not in any way be affected or impaired thereby.

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(k)                                  Binding Effect. This Agreement is offered to Assignor and Assignee for signature and it is understood that this Agreement shall be of no force and effect and shall not be binding upon Sublandlord unless and until (i) the Effective Date, (ii) Sublandlord shall have executed and delivered a copy of this Agreement to both Assignor and Assignee, (iii) Overlandlord has provided Sublandlord with a copy of Overlandlord’s written fully executed consent to the (a) assignment and assumption herein, (b) amendment to Sublease provisions in Section 9 hereof, and (c) Subtenant’s Work plans in accordance with the terms of the Overlease and Sublease, and, (iv) Overlandlord has provided Sublandlord with the fully executed 2^nd Amendment to Overlease.

(l)                                     Governing Law. This Agreement shall for all purposes be construed in accordance with, and governed by, the laws of the Commonwealth of Massachusetts.

(m)                               Conflict. As to Sublandlord, if there shall be any conflict or inconsistency between the terms, covenants and conditions of this Agreement and those of the Sublease, and the terms, covenants and conditions of any other document, then the terms, covenants and conditions of this Agreement and the Sublease shall prevail. The parties hereto agree that, as to Sublandlord, this Agreement is the sole agreement and instrument (as affected by Landlord’s Assignment Consent) governing the terms of the assignment and that Sublandlord is not a party to any other documents pertaining to the assignment of the Sublease from Assignor to Assignee, except the Landlord’s Assignment Consent. Further, as to Sublandlord, if there shall be any conflict or inconsistency between this Agreement and the terms, covenants or conditions of any other document related to the assignment, the terms, covenants and conditions of this Agreement shall prevail. For clarity, as between Assignor and Assignee only, no provision in this Agreement extinguishes or otherwise reduces Assignor’s obligations to Assignee set forth in the Purchase Agreement to retain, discharge, hold harmless and indemnify Assignee for certain obligations and liabilities as provided therein.

(n)                                 Survival. Assignor’s and Assignee’s representations and warranties in this Agreement to Sublandlord and to each other shall survive the Effective Date. Sublandlord’s representations in this Agreement to Assignor and Assignee shall survive the Effective Date.

(o)                                 Amendments and Waivers.     No amendment of any provision in this Agreement shall be valid, unless in writing and signed by the parties hereto and consented to in writing by Overlandlord (except that an amendment after the Effective Date hereof to the provisions of Section 9 hereof shall not require the signature or consent of Assignor). No failure or delay on the part of any party to exercise any rights under this Agreement shall operate or imply a waiver thereof, unless in a writing signed by the party to be charged.

[Signatures on next page.]

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EXECUTED under seal as of the date and year first above written.

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EXHIBIT H-2

Form of Landlord Consent

CONSENT TO ASSIGNMENT OF SUBLEASE

This Consent to Assignment of Sublease (this “Consent”) is made as of October     , 2007, by ARE-MA Region No. 28, LLC, a Delaware limited liability company, having an address of 385 East Colorado Boulevard, Suite 299, Pasadena, California 91101 (“Landlord”), Archemix Corp., a Delaware corporation, having an address of 300 Third Street, Cambridge, Massachusetts 02142 (“Tenant”), Momenta Pharmaceuticals, Inc., a Delaware corporation, having an address of 675 West Kendall Street, Cambridge, Massachusetts 02142 (“Assignor”), and Alnylam Pharmaceuticals, Inc., a Delaware corporation with an address of 300 Third Street, Cambridge, Massachusetts 02142 (“Assignee”) with reference to the following Recitals.

R E C I T A L S

A.                                    Landlord and Tenant have entered into that certain Office Lease dated as of April 11, 2005, as amended by that certain First Amendment to Lease dated as of July 9, 2006, and that certain Second Amendment to Lease dated October 31, 2007 (as so amended, the “Lease”) wherein Landlord leased to Tenant certain premises located on Levels 01, 02, P-1 and P-2 (the “Premises”) of the building commonly known as and located at 300 Third Street, Cambridge, Massachusetts, which Premises are more particularly described in the Lease.

B.                                    Tenant has subleased to Assignor a portion of the Premises consisting of approximately 22,364 rentable square feet located on Level 02 of the building (the “Original Subleased Premises”), more particularly described in and pursuant to the provisions of that certain Sublease dated as of September 8, 2006 (the “Sublease”).

C.                                    Assignor desires to assign to assign to Assignee its rights under the Sublease, and Assignee desire to assume the performance of Assignor’s obligations under the Sublease, upon the terms and conditions set forth herein and in that certain Assignment, Assumption and Consent Agreement and First Amendment to Sublease dated October     , 2007 (the “Assignment”), a copy of which is attached hereto as Exhibit A.

D.                                    Pursuant to said Assignment, Tenant is amending the location of a portion of the Original Subleased Premises, as set forth more specifically in such Assignment, and subleasing to Assignee an additional 164 rentable square feet located on Level P-1 of the building, whereby the Original Subleased Premises are amended pursuant to the Assignment to constitute 22,456 rentable square feet located on Levels 02 and P-1 of the building (the “Subleased Premises”).

E.                                      Tenant, Assignor and Assignee desire to obtain Landlord’s consent to the Assignment.

NOW, THEREFORE, in consideration of the foregoing and the agreements contained herein, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, Landlord hereby consents to the assignment of the Sublease to Assignee, such consent being subject to and upon the following terms and conditions, to which Tenant, Assignor and Assignee hereby agree:

1.                                       All initially capitalized terms not otherwise defined in this Consent shall have the meanings set forth in the Lease unless the context clearly indicates otherwise.

300 Third Street, Cambridge

Archemix/Momenta Sublease

© Alexandria Real Estate Equities, Inc. 1999

CONFIDENTIAL-DO NOT COPY

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2.                                       This Consent shall not be effective and the Assignment shall not be valid nor shall Assignee take possession of the Subleased Premises (i) unless and until Landlord shall have received a fully executed counterpart of this Consent and a fully executed counterpart of the Assignment, and (ii) provided that the foregoing conditions are satisfied, until the “Effective Date,” as that term is defined in the Assignment. Tenant and Assignor each represent and warrant to Landlord that the copy of the Assignment attached hereto as Exhibit A is true, correct and complete in all respects.

3.                                       Landlord’s consent set forth herein is subject to the following:

a.                                       Any and all proposed alterations, additions or improvements to be made in connection with Assignee’s occupancy of the Subleased Premises (collectively, “Assignment Improvements”) shall only be performed pursuant to and in compliance with all of the terms of the Lease;

b.                                      Tenant and Assignee shall comply with the provisions of the Lease regarding any and all Hazardous Materials to be used, stored or maintained in connection with Assignee’s proposed use of the Subleased Premises; and

c.                                       Pursuant to and in accordance with the terms of the Lease, those Assignment Improvements which constitute specialty Alterations may be required to be removed at the expiration or earlier termination of the Lease at no cost or expense to Landlord, with all damage occasioned by such removal being fully repaired.

d.                                      Pursuant to Article 16 of the Lease, Tenant shall pay to Landlord monthly, as Additional Rent under the Lease, a sum equal to fifty percent (50%) of the Excess Income (as such term is defined in Article 16(D) of the Lease) payable in connection with the Assignment and the Sublease, if any. Within sixty (60) days after the date of this Consent, Tenant shall provide Landlord with written documentation in form, scope and substance reasonably acceptable to Landlord verifying any and all of Tenant’s Transfer Expenses (as such term is defined in Article 16(D) of the Lease), or they shall be disregarded in computing Excess Income. Notwithstanding the foregoing, for purposes of this Consent only and for no other purpose, Landlord acknowledges and agrees that (i) the amount of $4,430,548.23, the components of which are itemized on the document entitled “Exhibit G, Detail Breakdown of Purchase Price,” which is attached hereto as Schedule 1, which amount is to be paid by Assignee for reimbursement of certain tenant improvement build-out costs (including sublease rent during the period of such buildout) and any adjustments to such sublease rent, whether paid by Assignor or Assignee, arising from the recalculation of operating expenses, utilities, real estate taxes and/or other rent adjustments provided for in the Sublease, for the period prior to the effective date of the Assignment, shall not be considered as a sum or value given in consideration of the assignment for purposes of determining Excess Income under Article16(D) of the Lease, (ii) the “Sublandlord’s Costs” (as defined in the Assignment) reimbursed to Tenant by Assignor or Assignee (and as may be reimbursed between Assignor and Assignee) shall not be considered as a sum or value given in consideration of the assignment for purposes of determining Excess Income under Article 16(D) of the Lease, and (iii) the “Transfer Expenses” (as defined in Article 16(D) of the

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Lease) in the amount of $256,210.77 have been approved and acknowledged by Landlord in connection with any Excess Income under Article 16(D) of the Lease arising from the Sublease or Assignment.

4.                                       Landlord neither approves nor disapproves the terms, conditions and agreements contained in the Assignment, all of which in all events shall be subordinate and at all times subject to: (a) all of the covenants, agreements, terms, provisions and conditions contained in the Lease, (b) superior ground leases, mortgages, deeds of trust, or any other hypothecation or security now existing or hereafter placed upon the real property of which the Premises are a part and to any and all advances secured thereby and to all renewals, modifications, consolidations, replacements and extensions thereof, and (c) all matters of record affecting the Premises and all laws, ordinances and regulations now or hereafter affecting the Premises. Without limiting the foregoing, pursuant to the terms of Section 10 of the Consent to Sublease (as defined in Section 11 hereof) and the terms of Article 16 of the Lease, Landlord hereby consents to the amendment of the Sublease as set forth in the Assignment.

5.                                       Nothing contained herein or in the Assignment or the Sublease shall be construed to:

a.                                       Modify, waive, impair, or affect any of the terms, covenants or conditions contained in the Lease, including Tenant’s obligation to obtain any required consents for any other or future assignments or sublettings (except that it is understood that the amendments to the Sublease contained in the Assignment, as consented to by Landlord in Section 4 hereof, by their terms modify and affect the terms of the Sublease), or to waive any breach thereof, or any rights or remedies of Landlord under the Lease against any person, firm, association or corporation liable for the performance thereof, or to enlarge or increase Landlord’s obligations or liabilities under the Lease (including, without limitation, any liability to Assignor or Assignee for any portion of the security deposit held by Tenant under the Sublease), and all terms, covenants and conditions of the Lease are hereby declared by each of Landlord, Tenant, Assignor and Assignee to be in full force and effect; provided, however that from and after the time that this Consent is effective and the Assignment is valid as set forth in Section 2 hereof and Section 1 of the Assignment, as between Assignor and Landlord only (but not as between Assignor and any other party), notwithstanding anything contained in the Lease or Consent to Sublease (as defined in Section 11 hereof), Assignor shall have no further ongoing obligations to pay rent or other sums due under the Lease with respect to the Subleased Premises or to perform the obligations of Tenant under the Lease with respect to the Subleased Premises (it being understood that the foregoing shall not affect any obligations of Assignor with respect to the time prior to the effective date of the Assignment).

b.                                      require Landlord to accept any payments from Assignor or Assignee on behalf of Tenant, except as expressly provided in Section 8 hereof.

Tenant shall remain liable and responsible for the due keeping, performance and observance of all the terms, covenants and conditions set forth in the Lease on the part of the Tenant to be kept, performed and observed and for the payment of the Base Rent, Additional Rent and all other sums now and hereafter becoming payable thereunder for all of the Premises, including, without limitation, the Subleased Premises.

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6.                                       Notwithstanding anything in the Assignment or Sublease to the contrary:

a.                                       Assignee does hereby expressly assume and agree to be bound by and to perform and comply with, for the benefit of Landlord, each and every obligation of Assignee under the Sublease and, to the extent applicable to the Subleased Premises or the Sublease, each and every obligation of Tenant under the Lease, Assignee agrees that it shall not do anything which violates the terms of the Lease to the extent applicable to the Subleased Premises or the Sublease.

b.                                      Landlord and Assignee each hereby release the other, and waive their respective rights of recovery against the other for direct or consequential loss or damage arising out of or incident to the perils covered by property insurance carried by such party to the extent of such insurance and waive any right of subrogation which might otherwise exist in or accrue to any person on account thereof.

c.                                       Tenant, Assignor and Assignee each agree to each of the terms and conditions of this Consent, and upon any conflict between the terms of the Sublease and this Consent, or between the terms of the Assignment and this Consent, the terms of this Consent shall control; provided, however, that as between Tenant, Assignor and Assignee only, upon any conflict between the terms of the Assignment and this Consent, the terms of the Assignment shall control.

d.                                     Except in accordance with the terms and conditions of the Lease, there shall be no further subletting or assignment of all or any portion of the Premises demised under the Lease (including the Subleased Premises demised by the Sublease) or further assignment of the Lease or Sublease.

e.                                      If Landlord terminates the Lease as a result of a default by Tenant thereunder, Tenant terminates the Lease pursuant to the terms of Article 33 of the Lease (and in such event Assignee shall have no claims against Tenant for exercising such Lease termination right), or the Lease terminates before the expiration date thereof (as the same may be extended pursuant to and in accordance with the Lease) for any other reason (an “Early Lease Termination”), the Sublease shall automatically terminate concurrently therewith; provided, however, Landlord and Assignee agree that, as between Landlord and Assignee only, if such termination of the Lease occurs during the time period of Assignee’s tenancy under the Sublease of the Subleased Premises, then immediately upon such termination of the Lease:

(i)                                        The Subleased Premises shall automatically be added to and made a part of the premises that are leased by Landlord to Assignee pursuant to that certain Lease dated as of September 26, 2003 by and between Landlord, as successor in interest to Three Hundred Third Street LLC, as landlord, and Assignee as tenant (the “Alnylam Lease”) with respect to premises on Levels 03 and 04 and Peripheral Spaces (as defined in the Alnylam Lease and referred to herein as the “Existing Alnylam Premises”) in the Building, such that the Subleased Premises shall be made subject to and part of the Alnylam Lease and subject to the terms and conditions of the Alnylam Lease and the additional provisions set forth in Section 6(e)(iii) hereof;

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(ii)                                     Assignee as tenant shall attorn to Landlord and shall have the rights and obligations of tenant under the Alnylam Lease with respect to the Subleased Premises, and all of the terms and conditions of the Alnylam Lease, together with the additional provisions as set forth in Section 6(e)(iii) hereof, shall apply only as between Landlord and Assignee with respect to the Subleased Premises; and

(iii)                                  the Alnylam Lease shall be automatically amended accordingly to add the Subleased Premises to the Existing Alnylam Premises demised under the Alnylam Lease, to adjust the Tenant’s Pro Rata Share under the Alnylam Lease for the addition of the Subleased Premises to the rentable square feet of the Existing Alnylam Premises, and to add the following additional provisions to the Alnylam Lease:

(1)  The Monthly Rent (as defined in the Alnylam Lease) for the Subleased Premises shall be at the rate set forth for Base Rent under the Lease, subject to adjustment for specific Lease Year time periods as set forth in the Lease as follows:  (A) $43.00 per rentable square foot of the Subleased Premises through the last day of Lease Year 3 (as such Lease Year is defined in the Lease), (B) $45.00 per rentable square foot of the Subleased Premises from the first day of Lease Year 4 through the last day of Lease Year 6 (as such Lease Years are defined in the Lease) and (C) $46.00 per rentable square foot of the Subleased Premises from the first day of Lease Year 7 through the last day of Lease Year 10 (as such Lease Years are defined in the Lease). Monthly Rent (under the Alnylam Lease) with respect to the Subleased Premises for any Extended Term of the Alnylam Lease shall be determined in the same manner as provided in the Alnylam Lease for the determination of Extended Term Monthly Rent for the remainder of the Existing Alnylam Premises;

(2)  If at the time of the Early Lease Termination Landlord is obligated (A) under Section III of the “Work Letter” (as defined in the Lease) to provide Tenant thereunder with any unpaid portion of the “Tenant Work Allowance” or “Additional Work Allowance” (as such terms are defined in the Lease), or (B) under Section III of such Work Letter to apply any credits to Monthly Rent under the Lease on account of any ”Allowance Excess” (as such term is defined in the Lease), then to the extent that Assignee is fulfilling the obligations of the Tenant under the Work Letter with respect to the Subleased Premises and is entitled to such portion of the Tenant Work Allowance and/or Additional Work Allowance allocable to the Subleased Premises, and to the extent that neither Tenant, nor Assignor, is entitled to payment for such allocable portion of the Tenant Work Allowance and/or Additional Work Allowance and/or entitled to such credit on account of any Allowance Excess, and provided further that Assignee is not in default under the Alnylam Lease, Landlord shall, subject to and in accordance with the provisions of said Work Letter, provide Assignee with any such unpaid part, if any, of the portion of the Tenant Work Allowance and Additional Work Allowance allocable to the Subleased Premises, and apply such allocable portion of such credit, if

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any, to Assignee’s obligations with respect to the Subleased Premises to pay Monthly Rent under the Alnylam Lease; and

(3)  Subject to payment of the Parking Fee (as that term is defined in the Alnylam Lease) therefor and the terms and conditions of the Alnylam Lease pertaining to parking, the number of parking spaces under the Alnylam Lease shall be increased by 24 parking spaces, which is, as between Tenant and Assignee, the number of parking spaces to which Assignee is entitled under the Sublease as of the effective date of the Assignment.

In the event of such Early Lease Termination and upon request of Landlord, Assignee shall execute and deliver a written confirmation of the foregoing amendment to the Alnylam Lease as such amendment is contained in this Section 6(e).

f.                                        Landlord shall not be (a) liable for any prior act or omission of Tenant under the Lease prior to any Early Lease Termination or for any defaults of Assignor under the Sublease prior to such Early Lease Termination, (b) subject to any defenses or offsets previously accrued which Assignee may have against Tenant or Assignor for any period prior to such Early Lease Termination, or (c) be bound by any changes or modifications made to the Sublease without the prior written consent of Landlord. Landlord and Assignee agree that, as between Landlord and Assignee only, interpretation of individual provisions of the Alnylam Lease, if as amended as contemplated hereby in the event of any Early Lease Termination, shall give effect to the parties’ mutual intention that, in the event of such Early Lease Termination and automatic amendment of the Alnylam Lease, notwithstanding anything contained in the Lease or Sublease as of the date hereof, the rights and obligations of Landlord and Assignee with respect to the Subleased Premises when added to the Alnylam Lease shall be as “Landlord” and “Tenant” respectively under the Alnylam Lease subject to the inclusion of the additional provisions in the Alnylam Lease with respect to the Subleased Premises, as set forth in Section 6(e)(iii) hereof.

g.                                     Within thirty (30) days after request therefor, Tenant shall reimburse Landlord for all of Landlord’s reasonable out-of-pocket costs and expenses incurred to third parties in connection with the Assignment and this Consent.

h.                                     Tenant and Assignee agree that, as between Tenant and Assignee only, (i) all references in this Consent to the Lease shall be deemed to refer only to the non-redacted portions of the Lease attached to the Sublease, and (ii) Tenant shall indemnify and hold Assignee harmless from and against any liabilities or obligations which may by this Consent be imposed on Assignee under redacted portions of the Lease.

7.                                       Any act or omission of Assignor or Assignee or anyone claiming under or through either Assignor or Assignee, which act or omission violates any of the provisions of the Lease shall be deemed a violation of the Lease by Tenant.

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8.                                       Upon a default by Tenant under the Lease, Landlord may proceed directly against Tenant, any guarantors or anyone else liable under the Lease or the Sublease without first exhausting Landlord’s remedies against any other person or entity liable thereon to Landlord. If Landlord gives Assignee notice that Tenant or Assignor is in default under the Lease after the giving of any applicable notice and the expiration of any applicable grace or cure period, Assignee shall thereafter make directly to Landlord all payments otherwise due Tenant or Assignor, which payments will be received by Landlord without any liability to Landlord except to credit such payments against amounts due under the Lease. The mention in this Consent of any particular remedy shall not preclude Landlord from any other remedy in law or in equity.

9.                                       Tenant shall pay any brokerage commissions or fees that may be payable as a result of or in connection with the Sublease and/or Assignment, and Tenant hereby indemnifies and agrees to hold Landlord harmless from and against any loss or liability arising therefrom or from any other commissions or fees payable in connection with the Sublease and/or Assignment which result from the actions of Tenant. Assignor hereby indemnifies and agrees to hold Landlord harmless from and against any loss or liability arising from any commissions or fees payable in connection with the Sublease and/or Assignment which result from the actions of Assignor. Assignee hereby indemnifies and agrees to hold Landlord harmless from and against any loss or liability arising from any commissions or fees payable in connection with the Sublease and/or Assignment which result from the actions of Assignee. As between Tenant, Assignor and Assignee only, however, responsibility for the payment of any brokerage commissions or fees that may be payable as a result of or in connection with the Assignment is specifically set forth in Section 11 of the Assignment.

10.                                 Tenant, Assignor and Assignee each agrees that it will not modify or amend the Sublease or Assignment in any way without the prior written consent of Landlord, which consent shall not be unreasonably withheld or delayed. Tenant, Assignor and Assignee hereby agree that it shall be reasonable for Landlord to withhold its consent to any modification or amendment of the Sublease which would change the permitted use of the Subleased Premises or which would affect Landlord’s status as a real estate investment trust. Any modification or amendment of the Sublease without Landlord’s prior written consent shall be void and of no force or effect.

11.                                 This Consent may not be changed orally, but only by an agreement in writing signed by Landlord and the party against whom enforcement of any change is sought. This Consent supersedes all prior understandings and agreements, whether written or oral, between Landlord and any other party hereto with respect to the consent of the Landlord to the assignment of the Sublease; provided, however, that the Consent to Sublease dated October 23, 2006 by and among Landlord, Tenant and Assignor (the “Consent to Sublease”) shall continue to apply and remains in full force and effect with respect to the subject matter contained therein. As between Tenant and Assignor only, and as between Tenant and Assignee only, however, in the event of any conflict between the terms of this Consent, the terms of any other document and the terms of this Assignment, the Assignment controls.

12.                                 This Consent may be executed in any number of counterparts, each of which shall be deemed an original, but all of which when taken together shall constitute but one and the same instrument.

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13.                                 This Consent and the legal relations between the parties hereto shall be governed by and construed and enforced in accordance with the internal laws of the Commonwealth of Massachusetts, without regard to its principles of conflicts of law.

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IN WITNESS WHEREOF, Landlord, Tenant, Assignor and Assignee have caused their duly authorized representatives to execute this Consent as of the date first above written.

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EXHIBIT H-3

Form of Second Amendment to Overlease

Note: Momenta Pharmaceuticals, Inc. is not a party to this Exhibit H-3. Pursuant to Item 601 of Regulation S-K, such exhibit is not being filed herewith.

EXHIBIT H-4

ASSIGNMENT AND ASSUMPTION OF CONSTRUCTION CONTRACT

THIS ASSIGNMENT AND ASSUMPTION OF CONSTRUCTION CONTRACT (the “Assignment”) is made as of October         , 2007 (the “Effective Date”) by Momenta Pharmaceuticals, Inc. (“Assignor”) and Alnylam Pharmaceuticals, Inc. (“Assignee”).

WHEREAS, Assignor is the owner under that certain Standard Form of Agreement between Owner and Contractor (AIA Document A111-1997) dated May 2, 2007, as modified by three Prime Contract Change Orders dated July 10, 2007, August 27, 2007 and October 1, 2007 (as so modified, the “Contract”), with F.L. Caulfield & Sons, Inc., as contractor (“Contractor”) with respect to the project (the “Project”) on the second floor of the Building located at 300 Third Street, Cambridge, Massachusetts. A true copy of the Contract is attached hereto as Exhibit A; and

WHEREAS, Assignor wishes to assign to Assignee, and Assignee wishes to assume Assignor’s interest in the Contract;

NOW, THEREFORE, incorporating the recitals above and in consideration of the mutual promises herein contained and other good and valuable consideration, receipt and sufficiency of which is hereby acknowledged, Assignor and Assignee hereby agree as follows:

1.                                       Assignment of Contract. Assignor, for value received, hereby transfers and assigns to Assignee all of Assignor’s right, title and interest in and to the Contract. Notwithstanding the foregoing, Assignor does not assign, and hereby reserves all rights to, any proceeds from the claim made by Assignor to the Contractor (and/or subcontractor) for reimbursement in the amount of $14,527.23 paid by Assignor to Archemix Corp. for sprinkler valve damage incurred in connection with the Project.

2.                                       Assumption of Obligations by Assignee. By acceptance of this Assignment, Assignee hereby unconditionally assumes and agrees to perform all of the obligations and covenants of Assignor as owner under the Contract, arising from and after the Effective Date. Assignee agrees for the benefit of Contractor that Contractor shall have the right to enforce against Assignee all of the Assignor’s obligations, liabilities and duties under the Contract to be performed by Assignor as fully and completely as if Assignee had originally executed the Contract as the owner thereunder.

3.                                       Representations. Assignor represents as follows:

a.                                       The Contract is a complete statement of the agreement between the parties with respect to Project referred to therein.

b.                                      A true and complete copy of the Contract is attached hereto as Exhibit A. A copy of a Project Book maintained by Assignor for the Project including true copies of the schedule of values, releases of liens and insurance certificates received by Assignor is attached hereto as Exhibit B.

c.                                       The Contract is presently in full force and effect according to its terms and is the valid and binding obligation of the undersigned as of the Effective Date.

d.                                      Contractor has been paid $3,222,564.00 of the Contract Sum due under the Contract.

g.                                      Assignor, as of the Effective Date, is not in default under the terms of the Contract. To Assignor’s knowledge, Contractor is not in default in the performance of its obligations to Assignor under the Contract.

4.                                       Successors and Assigns. This Assignment shall inure to the benefit of the parties, their assigns and successors in interest or in title or in both.

5.                                       Governing Law. This Assignment shall be governed by and construed in accordance with laws of the Commonwealth of Massachusetts.

6.                                       Consent. This Assignment shall be of no force or effect unless and until Contractor shall give its written consent hereto.

{Signatures Follow}

IN WITNESS WHEREOF, this Assignment has been executed by Assignor and Assignee as a sealed instrument as of the day and year first above written.

Assignor:

MOMENTA PHARMACEUTICALS, INC.

CONTRACTOR CONSENT

The undersigned, being the Contractor under the above described Contract, subject to the covenants, agreements, terms, provisions and conditions contained in the Contract and this Assignment, hereby consents to the assignment of the Contract to Assignee, and agrees to accept the Assignee as the owner under the Contract.

EXHIBIT H-5

ASSIGNMENT AND ASSUMPTION OF ARCHITECT CONTRACT

THIS ASSIGNMENT AND ASSUMPTION OF ARCHITECT CONTRACT (the “Assignment”) is made as of October         , 2007 (the “Effective Date”) by Momenta Pharmaceuticals, Inc. (“Assignor”) and Alnylam Pharmaceuticals, Inc. (“Assignee”).

WHEREAS, Assignor and Olson Lewis Dioli & Doktor, Architects & Planners Incorporated (the “Architect”) are parties to that certain pursuant to a fee proposal agreement dated October 4, 2006, as modified by letter agreement dated August 19, 2007 (as so modified, the “Contract”) with respect to the project (the “Project”) on the second floor of the Building located at 300 Third Street, Cambridge, Massachusetts. A true copy of the Contract is attached hereto as Exhibit A-1;

WHEREAS, pursuant to the Architect Contract, the Architect has produced certain drawings and specifications (the “Drawings”). True copies of the Drawings are attached hereto as Exhibit A-2; and

WHEREAS, Assignor wishes to assign to Assignee, and Assignee wishes to assume Assignor’s interest in the Contract and the Drawings;

NOW, THEREFORE, incorporating the recitals above and in consideration of the mutual promises herein contained and other good and valuable consideration, receipt and sufficiency of which is hereby acknowledged, Assignor and Assignee hereby agree as follows:

1.                                       Assignment of Contract. Assignor, for value received, hereby transfers and assigns to Assignee all of Assignor’s right, title and interest in and to the Contract and the Drawings.

2.                                       Assumption of Obligations by Assignee. By acceptance of this Assignment, Assignee hereby unconditionally assumes and agrees to perform all of the obligations and covenants of Assignor as owner under the Contract, arising from and after the Effective Date. Assignee agrees for the benefit of the Architect that the Architect shall have the right to enforce against Assignee all of the Assignor’s obligations, liabilities and duties under the Contract to be performed by Assignor as fully and completely as if Assignee had originally executed the Contract.

3.                                       Representations. Assignor represents as follows:

a.                                       The Contract is a complete statement of the agreement between the parties with respect to Project referred to therein.

b.                                      True and complete copies of the Contract and the Drawings are attached hereto as Exhibit A-1 and A-2.

c.                                       The Contract is presently in full force and effect according to its terms and is the valid and binding obligation of the undersigned as of the Effective Date.

d.                                      The Architect has been paid $195,518.00 under the Contract.

g.                                      Assignor, as of the Effective Date, is not in default under the terms of the Contract. To Assignor’s knowledge, the Architect is not in default in the performance of its obligations to Assignor under the Contract.

4.                                       Successors and Assigns. This Assignment shall inure to the benefit of the parties, their assigns and successors in interest or in title or in both.

5.                                       Governing Law. This Assignment shall be governed by and construed in accordance with laws of the Commonwealth of Massachusetts.

6.                                       Consent. This Assignment shall be of no force or effect unless and until the Architect shall give its written consent hereto.

{Signatures Follow}

IN WITNESS WHEREOF, this Assignment has been executed by Assignor and Assignee as a sealed instrument as of the day and year first above written.

ARCHITECT CONSENT

The undersigned, being the Architect under the above described Contract, subject to the covenants, agreements, terms, provisions and conditions contained in the Contract and this Assignment, hereby consents to the assignment of the Contract to Assignee, and agrees to accept the Assignee in the place and stead of the Assignor under the Contract.

EXHIBIT H-6

Bill of Sale

KNOW ALL MEN BY THESE PRESENTS that Momenta Pharmaceuticals, Inc., a Delaware corporation (“Seller”) for consideration of Ten and 00/100 Dollars ($10.00) and other good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, does hereby grant, sell, transfer and deliver unto Alnylam Pharmaceuticals, Inc., a Delaware corporation (“Purchaser”), the furniture, non-leasehold fixtures(3) and equipment described on Schedule A attached hereto.

And Seller does hereby warrant, covenant and agree that it has marketable title to said furniture, fixtures and equipment, free of all liens and encumbrances arising by or through Seller.

By acceptance of said furniture, fixtures and equipment, Purchaser hereby agrees that said furniture, fixtures and equipment is sold “AS-IS,” “WHERE-IS,” WITH ALL FAULTS, WITHOUT WARRANTIES OF ANY KIND WHATSOEVER, EXPRESS OR IMPLIED (EXCEPT, SELLER WARRANTS THAT IT HAS TITLE TO THE SAID furniture, fixtures and equipment), INCLUDING NO WARRANTIES OF MERCHANTABILITY, FITNESS FOR PARTICULAR PURPOSE, CONFORMITY TO ANY SPECIFICATIONS AND NON-INFRINGEMENT OF THIRD PARTY RIGHTS.

IN WITNESS WHEREOF, the undersigned has hereunto set its hand and seal as of the          day of October, 2007.

(3)  To the extent any fixtures are part of the leasehold estate pursuant to that certain Sublease dated as of September 8, 2006, as amended (the “Sublease”) between Archemix Corp., as sublandlord, and Seller, as subtenant, ownership of such fixtures shall be governed by the Sublease.

EXHIBIT H-7

ASSIGNMENT AND ASSUMPTION OF PURCHASE ORDERS

THIS ASSIGNMENT AND ASSUMPTION OF PURCHASE ORDERS (the “Assignment”) is made as of October         , 2007 (the “Effective Date”) by Momenta Pharmaceuticals, Inc. (“Assignor”) and Alnylam Pharmaceuticals, Inc. (“Assignee”).

WHEREAS, Assignor has made certain purchase orders (each, a “Purchase Order” and collectively, the “Purchase Orders”) with respect to equipment and furniture for the project on the second floor of the Building located at 300 Third Street, Cambridge, Massachusetts. True copies of the Purchase Orders are attached hereto as Exhibit A-1;  and

WHEREAS, Assignor wishes to assign to Assignee, and Assignee wishes to assume Assignor’s interest in the Purchase Orders;

NOW, THEREFORE, incorporating the recitals above and in consideration of the mutual promises herein contained and other good and valuable consideration, receipt and sufficiency of which is hereby acknowledged, Assignor and Assignee hereby agree as follows:

1.                                       Assignment of Purchase Orders. Assignor, for value received, hereby transfers and assigns to Assignee all of Assignor’s right, title and interest in and to the Purchase Orders, including all deposits made by Assignor thereunder (the “Deposits”).

2.                                       Assumption of Obligations by Assignee. By acceptance of this Assignment, Assignee hereby unconditionally assumes and agrees to perform all of the obligations and covenants of Assignor under the Purchase Orders, arising from and after the Effective Date.

3.                                       Representations. Assignor represents as follows:

a.                                       True and complete copies of the Purchase Orders are attached hereto as Exhibit A-1.

b.                                      Assignor has paid Deposits under the Purchase Orders in the amounts set forth on Exhibit A-2 attached hereto.

c.                                       Assignor, as of the Effective Date, is not in default under the terms of the Purchase Orders. To Assignor’s knowledge, the respective vendors under the Purchase Orders are not in default in the performance of its obligations to Assignor under the Purchase Orders.

4.                                       Further Assurances. Assignor agrees to reasonably cooperate with Assignee to enforce Assignor’s rights under the Purchase Orders; provided, that, such cooperation shall be without material expense to Assignor. If any action to enforce the Purchase Orders must be made in Assignor’s name, Assignor hereby irrevocably appoints Assignee its attorney-in-fact to enforce Assignor’s rights under the Purchase Orders, such appointment being deemed coupled with an interest.

5.                                       Successors and Assigns. This Assignment shall inure to the benefit of the parties, their assigns and successors in interest or in title or in both.

6.                                       Governing Law. This Assignment shall be governed by and construed in accordance with laws of the Commonwealth of Massachusetts.

{Signatures Follow}

IN WITNESS WHEREOF, this Assignment has been executed by Assignor and Assignee as a sealed instrument as of the day and year first above written.