Exhibit 99.3

Lock-Up Agreement

            , 2011

UBS Securities LLC

Leerink Swann LLC

    As representatives of the several Underwriters

named in Schedule A to the Underwriting Agreement

referred to herein

c/o UBS Securities LLC

299 Park Avenue

New York, New York 10171-0026

Ladies and Gentlemen:

This Lock-Up Agreement is being delivered to you in connection with the proposed Underwriting Agreement (the “Underwriting Agreement”) to be entered into by Verastem, Inc., a Delaware corporation (the “Company”), and you and the other underwriters named in Schedule A to the Underwriting Agreement, with respect to the public offering (the “Offering”) of common stock, par value $.0001 per share, of the Company (the “Common Stock”).

In order to induce you to enter into the Underwriting Agreement, the undersigned agrees that, for a period (the “Lock-Up Period”) beginning on the date hereof and ending on, and including, the date that is 180 days after the date of the final prospectus relating to the Offering, the undersigned will not, without the prior written consent of UBS Securities LLC (“UBS”) and Leerink Swann LLC (“Leerink”), (i) sell, offer to sell, contract or agree to sell, hypothecate, pledge, grant any option to purchase or otherwise dispose of or agree to dispose of, directly or indirectly, or establish or increase a put equivalent position or liquidate or decrease a call equivalent position within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, and the rules and regulations of the Securities and Exchange Commission (the “Commission”) promulgated thereunder (the “Exchange Act”) with respect to, any Common Stock or any other securities of the Company that are substantially similar to Common Stock, or any securities convertible into or exchangeable or exercisable for, or any warrants or other rights to purchase, the foregoing, (ii) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of Common Stock or any other securities of the Company that are substantially similar to Common Stock, or any securities convertible into or exchangeable or exercisable for, or any warrants or other rights to purchase, the foregoing, whether any such transaction is to be settled by delivery of Common Stock or such other securities, in cash or otherwise or (iii) publicly announce an intention to effect any transaction specified in clause (i) or (ii). The foregoing sentence shall not apply to (a) the registration of the offer and sale of Common Stock as contemplated by the Underwriting Agreement and the sale of the Common Stock to the Underwriters (as defined in the Underwriting Agreement) in the Offering; (b) bona fide gifts, provided the recipient thereof

agrees in writing with the Underwriters to be bound by the terms of this Lock-Up Agreement; (c) dispositions to any trust for the direct or indirect benefit of the undersigned and/or the immediate family of the undersigned, provided that such trust agrees in writing with the Underwriters to be bound by the terms of this Lock-Up Agreement; (d) dispositions to any corporation, partnership, limited liability company or other entity all of the beneficial ownership interests of which are held by the undersigned and/or the immediate family of the undersigned, provided that such entity agrees in writing with the Underwriters to be bound by the terms of this Lock-Up Agreement; (e) dispositions by will, other testamentary document or intestate succession to the legal representative, heir, beneficiary or a member of the immediate family of the undersigned, provided the recipient thereof agrees in writing with the Underwriters to be bound by the terms of this Lock-Up Agreement; (f) distributions to partners, members or stockholders of the undersigned, provided that each distributee agrees in writing with the Underwriters to be bound by the terms of this Lock-Up Agreement; (g) the exercise of options to purchase Common Stock outstanding as of the date hereof or granted under equity incentive plans in effect as of the date hereof or described in the registration statement filed with the Commission with respect to the Offering, provided that the underlying Common Stock continues to be subject to the terms of this Lock-Up Agreement and that no filing under the Exchange Act reporting a disposition of Common Stock to satisfy the exercise price and/or tax withholding obligations shall be required or shall be voluntarily made in connection with such exercise; (h) the repurchase of Common Stock by the Company in connection with termination of the undersigned’s employment with the Company; (i) the entry into any trading plan established pursuant to Rule 10b5-1 under the Exchange Act, provided that such plan does not provide for any sales or other dispositions of Common Stock during the Lock-Up Period and no public announcement or public disclosure of entry into such plan is made or required to be made; or (j) transactions relating to Common Stock acquired in open market transactions after the completion of the Offering, provided that no filing under the Exchange Act reporting a reduction in beneficial ownership of Common Stock by the undersigned shall be required or shall be voluntarily made in connection with such transactions. For purposes of this paragraph, “immediate family” shall mean the undersigned and the spouse, any lineal descendent, father, mother, brother, sister, nephew or niece of the undersigned.

If the undersigned is an officer or director of the Company, the undersigned further agrees that all of the foregoing provisions shall be equally applicable to any issuer-directed shares of Common Stock that the undersigned may purchase in the offering.

In addition, the undersigned hereby waives any rights the undersigned may have to require registration of Common Stock in connection with the filing of a registration statement relating to the Offering. The undersigned further agrees that, for the Lock-Up Period, the undersigned will not, without the prior written consent of UBS and Leerink, make any demand for, or exercise any right with respect to, the registration of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock, or warrants or other rights to purchase Common Stock or any such securities.

Notwithstanding the above, if (a) during the period that begins on the date that is fifteen (15) calendar days plus three (3) business days before the last day of the Lock-Up Period and ends on the last day of the Lock-Up Period, the Company issues an earnings release or material news or a material event relating to the Company occurs; or (b) prior to the expiration of

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the Lock-Up Period, the Company announces that it will release earnings results during the sixteen (16) day period beginning on the last day of the Lock-Up Period, then the restrictions imposed by this Lock-Up Agreement shall continue to apply until the expiration of the date that is fifteen (15) calendar days plus three (3) business days after the date on which the issuance of the earnings release or the material news or material event occurs.

In addition, the undersigned hereby waives any and all preemptive rights, participation rights, resale rights, rights of first refusal and similar rights that the undersigned may have in connection with the Offering or with any issuance or sale by the Company of any equity or other securities before the Offering, except for any such rights as have been heretofore duly exercised.

If the undersigned is an officer or director of the Company, (i) UBS and Leerink agree that, at least three business days before the effective date of any release or waiver of the foregoing restrictions in connection with a transfer of shares of Common Stock, UBS and Leerink will notify the Company of the impending release or waiver, and (ii) the Company has agreed in the Underwriting Agreement to announce the impending release or waiver by press release through a major news service at least two business days before the effective date of the release or waiver. Any release or waiver granted by UBS and Leerink hereunder to any such officer or director shall only be effective two business days after the publication date of such press release. The provisions of this paragraph will not apply if (a) the release or waiver is effected solely to permit a transfer not for consideration and (b) the transferee has agreed in writing to be bound by the same terms described in this letter to the extent and for the duration that such terms remain in effect at the time of the transfer.

The undersigned hereby confirms that the undersigned has not, directly or indirectly, taken, and hereby covenants that the undersigned will not, directly or indirectly, take, any action designed, or which has constituted or will constitute or might reasonably be expected to cause or result in the stabilization or manipulation of the price of any security of the Company to facilitate the sale or resale of shares of Common Stock.

The undersigned hereby authorizes the Company and its transfer agent, during the Lock-Up Period, to decline the transfer of or to note stop transfer restrictions on the stock register and other records relating to shares of Common Stock or other securities subject to this Lock-Up Agreement of which the undersigned is the record holder, and, with respect to shares of Common Stock or other securities subject to this Lock-Up Agreement of which the undersigned is the beneficial owner but not the record holder, the undersigned hereby agrees to cause such record holder to authorize the Company and its transfer agent, during the Lock-Up Period, to decline the transfer of or to note stop transfer restrictions on the stock register and other records relating to such shares or other securities.

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If (i) the Company notifies you in writing that it does not intend to proceed with the Offering, (ii) the registration statement filed with the Commission with respect to the Offering is withdrawn, (iii) the Underwriting Agreement does not become effective on or prior to June 30, 2012 or (iv) for any reason the Underwriting Agreement shall be terminated prior to the “time of purchase” (as defined in the Underwriting Agreement), this Lock-Up Agreement shall be terminated and the undersigned shall be released from its obligations hereunder.

Yours very truly,
	Name:

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