**Exhibit10.1**

 

SIRTRISPHARMACEUTICALS, INC.

 

### Amendment to

Warrant to Purchase Shares of Series B Preferred Stock of SirtrisPharmaceuticals, Inc.

 

Dated: April 17, 2008

 

Reference is made hereby to the warrant (the “Warrant”) issued toARE-770/784/790 Memorial Drive, LLC, a Delaware limited liability company (the “Investor”)by Sirtris Pharmaceuticals, Inc., a Delaware corporation (“the Company”)pursuant to a certain Lease Agreement, dated August 1, 2005, by andbetween the Company and the Investor. All capitalized terms used herein and not separately defined shall havethe meaning ascribed to them in the Warrant.

 

WHEREAS, the Company and the Investor desire to amend the Warrant;

 

NOW, THEREFORE, the Investor and the Company agree to the following:

 

1.     Amendment.  The Warrant is hereby amended such that Section 3.1and 3.2 of the Warrant shall be amended and restated to read in their entiretyas follows:

 

“3.1.*Reorganization.* In case at any time orfrom time to time, the Company shall (a) effect a reorganization, (b) consolidatewith or merge with or into any other person (whether or not the Company is thesurviving entity of such merger), or (c) effect a recapitalization, then,in each such case, the holder of this Warrant, on the exercise hereof as providedin Section 1 at any time after the consummation or effective date of suchreorganization, consolidation, merger or recapitalization as the case may be,shall receive, in lieu of the Series B Preferred Stock issuable on suchexercise prior to such consummation or such effective date, the stock and othersecurities and property (including cash) to which such holder would have beenentitled upon such consummation, if such holder had so exercised this Warrantimmediately prior thereto, all subject to further adjustment thereafter asprovided in Section 4.”

 

2.     Governing Law.  This Amendment shall be governed by andconstrued in accordance with the laws of The Commonwealth of Massachusettswithout reference to the choice of law principles thereof that would requirethe application of the laws of any other state.

 

3.     Counterparts. This Amendment may beexecuted in any number of counterparts, including by electronic or facsimiletransmission, each of which when so delivered shall be deemed an original, butall such counterparts taken together shall constitute but one and the sameinstrument.

 

*[Remainder of Page IntentionallyLeft Blank]*

 

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ThisAmendment is executed as of the date first written above.

 

**SIRTRISPHARMACEUTICALS, INC.**

 

 
| By:    | /s/  Garen Bohlin        |   |
|--------|--------------------------|--------|
| Name:  | Garen  Bohlin            |
| Title: | Chief  Operating Officer |
|        |                          |        |  |

 

 

**ARE-770/784/790MEMORIAL DRIVE, LLC**,a Delaware limited liability company

 

 

By:**ALEXANDRIA REAL ESTATE EQUITIES, L.P.,**         a Delaware limited partnership,managing member

 

 

By:**ARE-QRS CORP.,**         a Maryland corporation, generalpartner

 

 
| By:    | /s/ Dean Shigenaga      |   |
|--------|-------------------------|--------|
| Name:  | Dean Shigenaga          |
| Title: | Chief Financial Officer |
|        |                         |        |  |

 

 

[Signature Page toWarrant Amendment]

 

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