EXHIBIT 10.6**FIRST AMENDMENT TO LEASE**     THIS FIRST AMENDMENT TO LEASE (this “Amendment”) is entered into as of this28th day of February, 2007, by and between BMR-21 ERIE STREET LLC, a Delaware limitedliability company (“Landlord”), and VERTEX PHARMACEUTICALS INCORPORATED (“Tenant”).**RECITALS**     A. WHEREAS, Landlord and Tenant entered into that certain Lease dated as of November 14, 2006(the “Lease”), whereby Tenant leases certain premises (the “Premises”) fromLandlord at 21 Erie Street in Cambridge, Massachusetts (the “Building”);     B. WHEREAS, Landlord and Tenant desire to correct the square footage of the Premises; and     C. WHEREAS, Landlord and Tenant desire to modify and amend the Lease only in the respects andon the conditions hereinafter stated.**AGREEMENT**     NOW, THEREFORE, Landlord and Tenant, in consideration of the mutual promises contained hereinand for other good and valuable consideration, the receipt and sufficiency of which are herebyacknowledged, and intending to be legally bound, agree as follows:     1. Definitions. For purposes of this Amendment, capitalized terms shall have themeanings ascribed to them in the Lease unless otherwise defined herein.     2. Reference Data. In Section 1.1 of the Lease:          a. “BUILDING: The Building known as and numbered 21 Erie Street, Cambridge, Massachusetts,containing approximately 48,238 r.s.f.” is hereby replaced with “BUILDING: The Building known asand numbered 21 Erie Street, Cambridge, Massachusetts, containing approximately 48,627 r.s.f.”          b. “INITIAL ESTIMATED ANNUAL ADDITIONAL RENT: $203,364.24, based on $9.58/r.s.f.” is herebyreplaced with “INITIAL ESTIMATED ANNUAL ADDITIONAL RENT: $197,424.64, based on $9.58/r.s.f.”          c. “PREMISES: Approximately 21,228 r.s.f. of space in the Building as shown on ExhibitA” is hereby replaced with “PREMISES: Approximately 20,608 r.s.f. of space in the Building asshown on Exhibit A.”          d. “TENANT ALLOWANCE: $530,700 ($25/r.s.f.)” is hereby replaced with “TENANT ALLOWANCE:$515,200 ($25/r.s.f.).”          e. “TENANT’S PROPORTIONATE FRACTION: 44.01%” is hereby replaced with “TENANT’S PROPORTIONATEFRACTION: 42.38%.”Form dated12/22/06

 
     3. Brokers. Each party warrants and represents to the other party that it has had nodealings with any broker or agent in connection with this Amendment other than Richards Barry Joyce& Partners and CBRE/Lynch Murphy Walsh Advisors (“Brokers”) and covenants to defend withcounsel reasonably approved by such other party, hold harmless and indemnify such other party fromand against any and all cost, expense or liability arising from any breach of the foregoingwarranty and representation.     4. Effect of Amendment. Except as modified by this Amendment, the Lease and all thecovenants, agreements, terms, provisions and conditions thereof shall remain in full force andeffect and are hereby ratified and affirmed. The covenants, agreements, terms, provisions andconditions contained in this Amendment shall bind and inure to the benefit of the parties heretoand their respective successors and, except as otherwise provided in the Lease, their respectiveassigns. In the event of any conflict between the terms contained in this Amendment and the Lease,the terms herein contained shall supersede and control the obligations and liabilities of theparties. From and after the date hereof, the term “Lease” as used in the Lease shall mean theLease, as modified by this Amendment.     5. Miscellaneous. This Amendment becomes effective only upon execution and deliveryhereof by Landlord and Tenant. The captions of the paragraphs and subparagraphs in this Amendmentare inserted and included solely for convenience and shall not be considered or given any effect inconstruing the provisions hereof. All exhibits hereto are incorporated herein by reference.     6. Counterparts. This Amendment may be executed in one or more counterparts that,when taken together, shall constitute one original.[REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK]
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     IN WITNESS WHEREOF, Landlord and Tenant have hereunto set their hands as of the date and yearfirst above written, and acknowledge that they possess the requisite authority to enter into thistransaction and to execute this Amendment.**LANDLORD****:**     BMR-21 ERIE STREET LLC