Exhibit 10.1

INFINITY PHARMACEUTICALS, INC.

2010 STOCK INCENTIVE PLAN

The purpose of this 2010 Stock Incentive Plan (the “ Plan ”) of Infinity Pharmaceuticals, Inc., a Delaware corporation (the “ Company ”), is to advance the interests of the Company’s stockholders by enhancing the Company’s ability to attract, retain and motivate persons who are expected to make important contributions to the Company and by providing such persons with equity ownership opportunities and performance-based incentives that are intended to better align the interests of such persons with those of the Company’s stockholders. Except where the context otherwise requires, the term “ Company ” shall include any of the Company’s present or future parent or subsidiary corporations as defined in Sections 424(e) or (f) of the Internal Revenue Code of 1986, as amended, and any regulations thereunder (the “ Code ”) and any other business venture (including, without limitation, joint venture or limited liability company) in which the Company has a controlling interest, as determined by the Board of Directors of the Company (the “ Board ”).

All of the Company’s employees, officers and directors, as well as consultants and advisors to the Company (as such terms are defined and interpreted for purposes of Form S-8 under the Securities Act of 1933, as amended (the “ Securities Act ”), or any successor form) are eligible to be granted Awards under the Plan. Each person who is granted an Award under the Plan is deemed a “ Participant .” “ Award ” means Options (as defined in Section 5), SARs (as defined in Section 7), Restricted Stock (as defined in Section 8), Restricted Stock Units (as defined in Section 8) and Other Stock-Based Awards (as defined in Section 9) and Cash-Based Awards (as defined in Section 9).

(a) Administration by Board of Directors . The Plan will be administered by the Board. The Board shall have authority to grant Awards and to adopt, amend and repeal such administrative rules, guidelines and practices relating to the Plan as it shall deem advisable. The Board may construe and interpret the terms of the Plan and any Award agreements entered into under the Plan. The Board may correct any defect, supply any omission or reconcile any inconsistency in the Plan or any Award in the manner and to the extent it shall deem expedient and it shall be the sole and final judge of such expediency. All decisions by the Board shall be made in the Board’s sole discretion and shall be final and binding on all persons having or claiming any interest in the Plan or in any Award.

(b) Appointment of Committees . To the extent permitted by applicable law, the Board may delegate any or all of its powers under the Plan to one or more committees or subcommittees of the Board (a “ Committee ”). All references in the Plan to the “ Board ” shall mean the Board or a Committee of the Board or the officers referred to in Section 3(c) to the extent that the Board’s powers or authority under the Plan have been delegated to such Committee or officers.

(c) Delegation to Officers . To the extent permitted by applicable law, the Board may delegate to one or more officers of the Company the power to grant Options and other Awards that constitute rights under Delaware law (subject to any limitations under the Plan) to employees or officers of the Company and to exercise such other powers under the Plan as the Board may determine,  provided that the Board shall fix the terms of such Awards to be granted by such officers (including the

exercise price of such Awards, which may include a formula by which the exercise price will be determined) and the maximum number of shares subject to such Awards that the officers may grant; provided further , however, that no officer shall be authorized to grant such Awards to any “executive officer” of the Company (as defined by Rule 3b-7 under the Securities Exchange Act of 1934, as amended (the “ Exchange Act ”)) or to any “officer” of the Company (as defined by Rule 16a-1 under the Exchange Act). The Board may not delegate authority under this Section 3(c) to grant Restricted Stock, unless Delaware law then permits such delegation.

(d) Awards to Non-Employee Directors . Discretionary Awards to non-employee directors may be granted and administered only by a Committee, all of the members of which are independent directors as defined by Section 5605(a)(2) of the NASDAQ Marketplace Rules.

(a) Number of Shares; Share Counting .

(1) Authorized Number of Shares . Subject to adjustment under Section 11, Awards may be made under the Plan for up to 3,000,000 shares of common stock, $.001 par value per share, of the Company (the “ Common Stock ”), any or all of which Awards may be in the form of Incentive Stock Options (as defined in Section 5(b)). Shares issued under the Plan may consist in whole or in part of authorized but unissued shares or treasury shares. The Company shall not make any new Awards under any prior equity plans after the date the Plan is approved by the Company’s stockholders (the “Effective Date” ).

(2) Fungible Share Pool . Subject to adjustment under Section 11, any Award that is not a Full-Value Award shall be counted against the share limits specified in Section 4(a)(1) as one share for each share of Common Stock subject to such Award and any Award that is a Full-Value Award shall be counted against the share limits specified in Section 4(a)(1) as 1.35 shares for each one share of Common Stock subject to such Full-Value Award. “Full-Value Award” means any Restricted Stock Award or Other Stock-Based Award with a per share price or per unit purchase price lower than 100% of Fair Market Value (as defined below) on the date of grant. To the extent a share that was subject to an Award that counted as one share is returned to the Plan pursuant to Section 4(a)(3), each applicable share reserve will be credited with one share. To the extent that a share that was subject to an Award that counts as 1.35 shares is returned to the Plan pursuant to Section 4(a)(3), each applicable share reserve will be credited with 1.35 shares.

(3) Share Counting . For purposes of counting the number of shares available for the grant of Awards under the Plan:

(A) all shares of Common Stock covered by SARs shall be counted against the number of shares available for the grant of Awards under the Plan and against the sublimits listed in the first clause of this Section 4(a)(2); provided, however , that (i) SARs that may be settled only in cash shall not be so counted and (ii) if the Company grants an SAR in tandem with an Option for the same number of shares of Common Stock and provides that only one such Award may be exercised (a “ Tandem SAR ”), only the shares covered by the Option, and not the shares covered by the Tandem SAR, shall be so counted, and the expiration of one in connection with the other’s exercise will not restore shares to the Plan;

2

(B) if any Award granted under this Plan or the 2000 Stock Incentive Plan of the Company (formerly, the Discovery Partners International, Inc. 2000 Stock Incentive Plan) (i) expires or is terminated, surrendered or canceled without having been fully exercised or is forfeited in whole or in part (including as the result of shares of Common Stock subject to such Award being repurchased by the Company at the original issuance price pursuant to a contractual repurchase right) or (ii) results in any Common Stock not being issued (including as a result of an SAR that was settleable either in cash or in stock actually being settled in cash), the unused Common Stock covered by such Award shall again be available for the grant of Awards; provided, however , that (1) in the case of Incentive Stock Options, the foregoing shall be subject to any limitations under the Code, (2) in the case of the exercise of an SAR, the number of shares counted against the shares available under the Plan and against the sublimits listed in the first clause of this Section 4(a)(2) shall be the full number of shares subject to the SAR multiplied by the percentage of the SAR actually exercised, regardless of the number of shares actually used to settle such SAR upon exercise and (3) the shares covered by a Tandem SAR shall not again become available for grant upon the expiration or termination of such Tandem SAR;

(C) shares of Common Stock delivered (either by actual delivery, attestation, or net exercise) to the Company by a Participant to (i) purchase shares of Common Stock upon the exercise of an Award or (ii) satisfy tax withholding obligations (including shares retained from the Award creating the tax obligation) shall not be added back to the number of shares available for the future grant of Awards; and

(D) shares of Common Stock repurchased by the Company on the open market using the proceeds from the exercise of an Award shall not increase the number of shares available for future grant of Awards.

(b) Sub-limits . Subject to adjustment under Section 11, the following sub-limits on the number of shares subject to Awards shall apply:

(1) Section 162(m) Per-Participant Limit . The maximum number of shares of Common Stock with respect to which Awards may be granted to any Participant under the Plan shall be 1,000,000 per calendar year. For purposes of the foregoing limit, the combination of an Option in tandem with an SAR shall be treated as a single Award. The per Participant limit described in this Section 4(b)(1) shall be construed and applied consistently with Section 162(m) of the Code or any successor provision thereto, and the regulations thereunder (“ Section 162(m) ”).

(c) Substitute Awards . In connection with a merger or consolidation of an entity with the Company or the acquisition by the Company of property or stock of an entity, the Board may grant Awards in substitution for any options or other stock or stock-based awards granted by such entity or an affiliate thereof. Substitute Awards may be granted on such terms as the Board deems appropriate in the circumstances, notwithstanding any limitations on Awards contained in the Plan. Substitute Awards shall not count against the overall share limit set forth in Section 4(a)(1) or any sublimits contained in the Plan, except as may be required by reason of Section 422 and related provisions of the Code.

(a) General . The Board may grant options to purchase Common Stock (each, an “ Option ”) and determine the number of shares of Common Stock to be covered by each Option, the exercise price of each Option and the conditions and limitations applicable to the exercise of each Option, including conditions relating to applicable federal or state securities laws, as it considers necessary or advisable.

3

(b) Incentive Stock Options . An Option that the Board intends to be an “incentive stock option” as defined in Section 422 of the Code (an “ Incentive Stock Option ”) shall only be granted to employees of Infinity Pharmaceuticals, Inc., any of Infinity Pharmaceuticals, Inc.’s present or future parent or subsidiary corporations as defined in Sections 424(e) or (f) of the Code, and any other entities the employees of which are eligible to receive Incentive Stock Options under the Code, and shall be subject to and shall be construed consistently with the requirements of Section 422 of the Code. An Option that is not intended to be an Incentive Stock Option shall be designated a “ Nonstatutory Stock Option .” The Company shall have no liability to a Participant, or any other party, if an Option (or any part thereof) that is intended to be an Incentive Stock Option is not an Incentive Stock Option or if the Company converts an Incentive Stock Option to a Nonstatutory Stock Option.

(c) Exercise Price . The Board shall establish the exercise price of each Option and specify the exercise price in the applicable Option agreement. The exercise price shall be not less than 100% of the Fair Market Value (as defined in Section 5(j) below);  provided that if the Board approves the grant of an Option with an exercise price to be determined on a future date, the exercise price shall be not less than 100% of the Fair Market Value on such future date.

(d) Duration of Options . Each Option shall be exercisable at such times and subject to such terms and conditions as the Board may specify in the applicable option agreement; provided, however , that no Option will be granted with a term in excess of 10 years.

(e) Exercise of Options . Options may be exercised by delivery to the Company of a notice of exercise in a form (which may be electronic) approved by the Company, together with payment in full (in the manner specified in Section 5(f)) of the exercise price for the number of shares for which the Option is exercised. Shares of Common Stock subject to the Option will be delivered by the Company as soon as practicable following exercise.

(f) Payment Upon Exercise . Common Stock purchased upon the exercise of an Option granted under the Plan shall be paid for as follows:

(1) in cash or by check, payable to the order of the Company;

(2) except as may otherwise be provided in the applicable Option agreement or approved by the Board, in its sole discretion, by (i) delivery of an irrevocable and unconditional undertaking by a creditworthy broker to deliver promptly to the Company sufficient funds to pay the exercise price and any required tax withholding or (ii) delivery by the Participant to the Company of a copy of irrevocable and unconditional instructions to a creditworthy broker to deliver promptly to the Company cash or a check sufficient to pay the exercise price and any required tax withholding;

(3) to the extent provided for in the applicable Option agreement or approved by the Board, in its sole discretion, by delivery (either by actual delivery or attestation) of shares of Common Stock owned by the Participant valued at their Fair Market Value, provided (i) such method of payment is then permitted under applicable law, (ii) such Common Stock, if acquired directly from the Company, was owned by the Participant for such minimum period of time, if any, as may be established by the Board in its discretion and (iii) such Common Stock is not subject to any repurchase, forfeiture, unfulfilled vesting or other similar requirements;

(4) to the extent provided for in the applicable Option agreement or approved by the Board in its sole discretion, by delivery of a notice of “net exercise” to the Company, as a result of

4

which the Participant would receive (i) the number of shares underlying the portion of the Option being exercised, less (ii) such number of shares as is equal to (A) the aggregate exercise price for the portion of the Option being exercised divided by (B) the Fair Market Value on the date of exercise.

(5) to the extent permitted by applicable law and provided for in the applicable Option agreement or approved by the Board, in its sole discretion, by payment of such other lawful consideration as the Board may determine; or

(6) by any combination of the above permitted forms of payment.

(g) No Reload Options . No Option granted under the Plan shall contain any provision entitling the Participant to the automatic grant of additional Options in connection with any exercise of the original Option.

(h) No Dividend Equivalents . No option shall provide for the payment or accrual of dividend equivalents.

(i) Limitation on Repricing . Unless such action is approved by the Company’s stockholders, the Company may not (except as provided for under Section 11): (1) amend any outstanding Option granted under the Plan to provide an exercise price per share that is lower than the then-current exercise price per share of such outstanding Option, (2) cancel any outstanding option (whether or not granted under the Plan) and grant in substitution therefor new Awards under the Plan (other than Awards granted pursuant to Section 4(c)) covering the same or a different number of shares of Common Stock and having an exercise price per share lower than the then-current exercise price per share of the cancelled option, (3) cancel in exchange for a cash payment any outstanding Option with an exercise price per share below the then-current Fair Market Value, other than pursuant to Section 11, or (4) take any other action under the Plan that constitutes a “repricing” within the meaning of the rules of the NASDAQ Stock Market (“ NASDAQ ”).

(j) Fair Market Value . ‘Fair Market Value’ of a share of Common Stock for purposes of the Plan will be determined as follows:

(1) if the Common Stock trades on a national securities exchange, the closing sale price (for the primary trading session) on the date of grant; or

(2) if the Common Stock does not trade on any such exchange, the average of the closing bid and asked prices as reported by an authorized OTCBB market data vendor as listed on the OTCBB website (otcbb.com) on the date of grant; or

(3) if the Common Stock is not publicly traded, the Board will determine the Fair Market Value for purposes of the Plan using any measure of value it determines to be appropriate (including, as it considers appropriate, relying on appraisals) in a manner consistent with the valuation principles under Code Section 409A, except as the Board may expressly determine otherwise.

For any date that is not a trading day, the Fair Market Value of a share of Common Stock for such date will be determined by using the closing sale price or average of the bid and asked prices, as appropriate, for the immediately preceding trading day and with the timing in the formulas above adjusted accordingly. The Board can substitute a particular time of day or other measure of “closing sale price” or “bid and asked prices” if appropriate because of exchange or market procedures or can, in its sole

5

discretion, use weighted averages either on a daily basis or such longer period as complies with Code Section 409A.

The Board has sole discretion to determine the Fair Market Value for purposes of the Plan, and all Awards are conditioned on the participants’ agreement that the Administrator’s determination is conclusive and binding even though others might make a different determination.

(a) Initial Grant . Upon the commencement of service on the Board by any individual who is not then an employee of the Company or any subsidiary of the Company, such person shall automatically be granted a Nonstatutory Stock Option to purchase 9,375 shares of Common Stock (subject to adjustment under Section 6(e), 6(f) or 11).

(b) Annual Grant . On the date of each annual meeting of stockholders of the Company, each member of the Board of Directors of the Company who is both serving as a director of the Company immediately prior to and immediately following such annual meeting and who is not then an employee of the Company or any of its subsidiaries, shall automatically be granted a Nonstatutory Stock Option to purchase 5,625 shares of Common Stock (subject to adjustment under Section 6(e), 6(f) or 11); provided, however , that a director shall not be eligible to receive an option grant under this Section 6(b) unless such director served on the Board on the last day of the immediately preceding calendar year.

(c) Additional Grants . Upon the commencement of service in the following positions by any individual who is not then an employee of the Company or any of its subsidiaries, and each anniversary thereafter that such individual is continuing to serve in such position, such person shall automatically be granted a Nonstatutory Stock Option to purchase the number of shares of Common Stock (subject to adjustment under Section 6(e), 6(f) or 11) indicated below:

(1) if the individual serves as lead outside director of the Board, a Nonstatutory Stock Option to purchase 9,375 shares of Common Stock;

(2) if the individual serves as chair of the research and development committee of the Board, a Nonstatutory Stock Option to purchase 3,750 shares of Common Stock;

(3) if the individual serves as chair of the audit committee of the Board, a Nonstatutory Stock Option to purchase 3,750 shares of Common Stock;

(4) if the individual serves as chair of the compensation committee of the Board, a Nonstatutory Stock Option to purchase 1,875 shares of Common Stock; and

(5) if the individual serves as the chair of the nominating and corporate governance committee of the Board, if such individual is not also lead outside director of the board, a Nonstatutory Stock Option to purchase 1,875 shares of Common Stock.

(d) Terms of Director Options . Options granted under this Section 6 shall (i) have an exercise price equal to the closing sale price (for the primary trading session) of the Common Stock on the national securities exchange on which the Common Stock is then traded on the date of grant (or if the date of grant is not a trading day on such exchange, the trading day immediately prior to the date of

6

grant) or, if the Common Stock is not then traded on a national securities exchange, the Fair Market Value of the Common Stock, (ii) vest in equal quarterly installments on the last day of each calendar quarter provided that the individual is serving on the Board or in the positions listed in Section 6(c), as applicable, on such date, provided that no additional vesting shall take place after the Participant ceases to serve as a director and further provided that the Options granted under this Section 6 shall immediately vest in the case of death, disability or change in control, (iii) expire on the earlier of 10 years from the date of grant or one year following cessation of service on the Board and (iv) contain such other terms and conditions as the Board shall determine.

(e) Board Discretion . The Board retains the specific authority to increase or decrease from time to time the number of shares subject to Options granted under this Section 6.

(f) Non-exclusive Grants . The Board retains the specific authority to grant Options, SARs, Restricted Stock, Restricted Stock Units and Other Stock-Based Awards and Cash-Based Awards in addition to or in lieu of some or all of the Options provided for in this Section 6.

(a) General . The Board may grant Awards consisting of stock appreciation rights (“ SARs ”) entitling the holder, upon exercise, to receive an amount of Common Stock or cash or a combination thereof (such form to be determined by the Board) determined by reference to appreciation, from and after the date of grant, in the Fair Market Value of a share of Common Stock over the measurement price established pursuant to Section 7(b). The date as of which such appreciation is determined shall be the exercise date.

(b) Measurement Price . The Board shall establish the measurement price of each SAR and specify it in the applicable SAR agreement. The measurement price shall not be less than 100% of the Fair Market Value on the date the SAR is granted; provided that if the Board approves the grant of an SAR effective as of a future date, the measurement price shall be not less than 100% of the Fair Market Value on such future date.

(c) Duration of SARs . Each SAR shall be exercisable at such times and subject to such terms and conditions as the Board may specify in the applicable SAR agreement; provided, however , that no SAR will be granted with a term in excess of 10 years.

(d) Exercise of SARs . SARs may be exercised by delivery to the Company of a notice of exercise in a form (which may be electronic) approved by the Company, together with any other documents required by the Board.

(e) Dividend Equivalents. No SAR shall provide for the payment or accrual of dividends.

(f) Limitation on Repricing . Unless such action is approved by the Company’s stockholders, the Company may not (except as provided for under Section 11): (1) amend any outstanding SAR granted under the Plan to provide a measurement price per share that is lower than the then-current measurement price per share of such outstanding SAR, (2) cancel any outstanding SAR (whether or not granted under the Plan) and grant in substitution therefor new Awards under the Plan (other than Awards granted pursuant to Section 4(c)) covering the same or a different number of shares of Common Stock and having an exercise or measurement price per share lower than the then-current measurement price per share of the cancelled SAR, (3) cancel in exchange for a cash payment any outstanding SAR

7

with a measurement price per share below the then-current Fair Market Value, other than pursuant to Section 11, or (4) take any other action under the Plan that constitutes a “repricing” within the meaning of the rules of the NASDAQ.

(a) General . The Board may grant Awards entitling recipients to acquire shares of Common Stock (“ Restricted Stock ”), subject to the right of the Company to repurchase all or part of such shares at their issue price or other stated or formula price (or to require forfeiture of such shares if issued at no cost) from the recipient in the event that conditions specified by the Board in the applicable Award are not satisfied prior to the end of the applicable restriction period or periods established by the Board for such Award. The Board may also grant Awards entitling the recipient to receive shares of Common Stock or cash to be delivered at the time such Award vests (“ Restricted Stock Units ”) (Restricted Stock and Restricted Stock Units are each referred to herein as a “ Restricted Stock Award ”).

(b) Terms and Conditions for All Restricted Stock Awards . The Board shall determine the terms and conditions of a Restricted Stock Award, including the conditions for vesting and repurchase (or forfeiture) and the issue price, if any.

(c) Additional Provisions Relating to Restricted Stock .

(1) Dividends . Unless otherwise provided in the applicable Award agreement, any dividends (whether paid in cash, stock or property) declared and paid by the Company with respect to shares of Restricted Stock (“ Accrued Dividends ”) shall be paid to the Participant only if and when such shares become free from the restrictions on transferability and forfeitability that apply to such shares. Each payment of Accrued Dividends will be made no later than the end of the calendar year in which the dividends are paid to stockholders of that class of stock or, if later, the 15th day of the third month following the lapsing of the restrictions on transferability and the forfeitability provisions applicable to the underlying shares of Restricted Stock.

(2) Stock Certificates . The Company may require that any stock certificates issued in respect of shares of Restricted Stock, as well as dividends or distributions paid on such Restricted Stock, shall be deposited in escrow by the Participant, together with a stock power endorsed in blank, with the Company (or its designee). At the expiration of the applicable restriction periods, the Company (or such designee) shall deliver the certificates no longer subject to such restrictions to the Participant or if the Participant has died, to his or her Designated Beneficiary. “ Designated Beneficiary ” means (i) the beneficiary designated, in a manner determined by the Board, by a Participant to receive amounts due or exercise rights of the Participant in the event of the Participant’s death or (ii) in the absence of an effective designation by a Participant, the Participant’s estate.

(d) Additional Provisions Relating to Restricted Stock Units .

(1) Settlement . Upon the vesting of and/or lapsing of any other restrictions (i.e., settlement) with respect to each Restricted Stock Unit, the Participant shall be entitled to receive from the Company one share of Common Stock or (if so provided in the applicable Award agreement) an amount of cash equal to the Fair Market Value of one share of Common Stock. The Board may, in its discretion, provide that settlement of Restricted Stock Units shall be deferred, on a mandatory basis or at the election of the Participant in a manner that complies with Section 409A of the Code.

8

(2) Voting Rights . A Participant shall have no voting rights with respect to any Restricted Stock Units.

(3) Dividend Equivalents . The Award agreement for Restricted Stock Units may provide Participants with the right to receive an amount equal to any dividends or other distributions declared and paid on an equal number of outstanding shares of Common Stock (“ Dividend Equivalents ”). Dividend Equivalents may be paid currently or credited to an account for the Participant, may be settled in cash and/or shares of Common Stock and may be subject to the same restrictions on transfer and forfeitability as the Restricted Stock Units with respect to which paid, in each case to the extent provided in the Award agreement.

(a) General . Other Awards of shares of Common Stock, and other Awards that are valued in whole or in part by reference to, or are otherwise based on, shares of Common Stock or other property, may be granted hereunder to Participants (“ Other Stock-Based-Awards ”). Such Other Stock-Based Awards shall also be available as a form of payment in the settlement of other Awards granted under the Plan or as payment in lieu of compensation to which a Participant is otherwise entitled. Other Stock-Based Awards may be paid in shares of Common Stock or cash, as the Board shall determine. The Company may also grant Performance Awards or other Awards denominated in cash rather than shares of Common Stock (“ Cash-Based Awards ”).

(b) Terms and Conditions . Subject to the provisions of the Plan, the Board shall determine the terms and conditions of each Other Stock-Based Award or Cash-Based Award, including any purchase price applicable thereto.

(a) Grants . Restricted Stock Awards and Other Stock-Based Awards under the Plan may be made subject to the achievement of performance goals pursuant to this Section 10(i) (“ Performance Awards ”).

(b) Committee . Grants of Performance Awards to any Covered Employee (as defined below) intended to qualify as “performance-based compensation” under Section 162(m) (“ Performance-Based Compensation ”) shall be made only by a Committee (or a subcommittee of a Committee) comprised solely of two or more directors eligible to serve on a committee making Awards qualifying as “performance-based compensation” under Section 162(m). In the case of such Awards granted to Covered Employees, references to the Board or to a Committee shall be treated as referring to such Committee (or subcommittee). “ Covered Employee ” shall mean any person who is, or whom the Committee, in its discretion, determines may be, a “covered employee” under Section 162(m)(3) of the Code.

(c) Performance Measures . For any Award that is intended to qualify as Performance-Based Compensation, the Committee shall specify that the degree of granting, vesting and/or payout shall be subject to the achievement of one or more objective performance measures established by the Committee, which shall be based on the relative or absolute attainment of any combination of the following: (i) the entry into an arrangement or agreement with a third party for the development, commercialization, marketing or distribution of products, services or technologies, or for conducting a research program to discover and develop a product, service or technology, and/or the achievement of

9

milestones under such arrangement or agreement, including events that trigger an obligation or payment right; (ii) achievement of domestic and international regulatory milestones, including the submission of filings required to advance products, services and technologies in clinical development and the achievement of approvals by regulatory authorities relating to the commercialization of products, services and technologies; (iii) the achievement of discovery, preclinical and clinical stage scientific objectives, discoveries or inventions for products, services and technologies under research and development; (iv) the entry into or completion of a phase of clinical development for any product, service or technology, such as the entry into or completion of phase 1, 2 and/or 3 clinical trials; (v) the consummation of debt or equity financing transactions, or acquisitions of business, technologies and assets; (vi) new product or service releases; (vii) the achievement of qualitative or quantitative performance measures set forth in operating plans approved by the Board from time to time; and/or (viii) specified levels of product sales, net income, earnings before or after discontinued operations, interest, taxes, depreciation and/or amortization, operating profit before or after discontinued operations and/or taxes, sales, sales growth, earnings growth, cash flow or cash position, gross margins, stock price, market share, return on sales, assets, equity or investment, (ix) improvement of financial ratings, (x) achievement of balance sheet or income statement objectives, and/or (xi) total stockholder return. Such goals may reflect, as applicable, absolute entity or business unit performance or a relative comparison to the performance of a peer group of entities or other external measure of the selected performance criteria and may be absolute in their terms or measured against or in relationship to other companies comparably, similarly or otherwise situated. The Committee may specify that such performance measures shall be adjusted to exclude any one or more of (i) extraordinary items, (ii) gains or losses on the dispositions of discontinued operations, (iii) the cumulative effects of changes in accounting principles, (iv) the writedown of any asset, and (v) charges for restructuring and rationalization programs. Such performance measures: (i) may vary by Participant and may be different for different Awards; (ii) may be particular to a Participant or the department, branch, line of business, subsidiary or other unit in which the Participant works and may cover such period as may be specified by the Committee; and (iii) shall be set by the Committee within the time period prescribed by, and shall otherwise comply with the requirements of, Section 162(m). Awards that are not intended to qualify as Performance-Based Compensation may be based on these or such other performance measures as the Board may determine.

(d) Adjustments . Notwithstanding any provision of the Plan, with respect to any Performance Award that is intended to qualify as Performance-Based Compensation, the Committee may adjust downwards, but not upwards, the cash or number of shares payable pursuant to such Award, and the Committee may not waive the achievement of the applicable performance measures except in the case of the death or disability of the Participant or a change in control of the Company.

(e) Other . The Committee shall have the power to impose such other restrictions on Performance Awards as it may deem necessary or appropriate to ensure that such Awards satisfy all requirements for Performance-Based Compensation.

(a) Changes in Capitalization . In the event of any stock split, reverse stock split, stock dividend, recapitalization, combination of shares, reclassification of shares, spin-off or other similar change in capitalization or event, or any dividend or distribution to holders of Common Stock other than an ordinary cash dividend, (i) the number and class of securities available under the Plan, (ii) the share counting rules and sublimits set forth in Sections 4(a) and 4(b), (iii) the number and class of securities

10

and exercise price per share of each outstanding Option and each Option issuable under Section 6, (iv) the share and per-share provisions and the measurement price of each outstanding SAR, (v) the number of shares subject to and the repurchase price per share subject to each outstanding Restricted Stock Award and (vi) the share and per-share-related provisions and the purchase price, if any, of each outstanding Other Stock-Based Award, shall be equitably adjusted by the Company (or substituted Awards may be made, if applicable) in the manner determined by the Board. Without limiting the generality of the foregoing, in the event the Company effects a split of the Common Stock by means of a stock dividend and the exercise price of and the number of shares subject to an outstanding Option are adjusted as of the date of the distribution of the dividend (rather than as of the record date for such dividend), then an optionee who exercises an Option between the record date and the distribution date for such stock dividend shall be entitled to receive, on the distribution date, the stock dividend with respect to the shares of Common Stock acquired upon such Option exercise, notwithstanding the fact that such shares were not outstanding as of the close of business on the record date for such stock dividend.

(b) Reorganization Events .

(1) Definition . A “ Reorganization Event ” shall mean: (a) any merger or consolidation of the Company with or into another entity as a result of which all of the Common Stock of the Company is converted into or exchanged for the right to receive cash, securities or other property or is cancelled, (b) any transfer or disposition of all of the Common Stock of the Company for cash, securities or other property pursuant to a share exchange or other transaction or (c) any liquidation or dissolution of the Company.

(2) Consequences of a Reorganization Event on Awards Other than Restricted Stock .

(A) In connection with a Reorganization Event, the Board may take any one or more of the following actions as to all or any (or any portion of) outstanding Awards other than Restricted Stock on such terms as the Board determines (except to the extent specifically provided otherwise in an applicable Award agreement or another agreement between the Company and the Participant): (i) provide that such Awards shall be assumed, or substantially equivalent Awards shall be substituted, by the acquiring or succeeding corporation (or an affiliate thereof), (ii) upon written notice to a Participant, provide that all of the Participant’s unexercised Awards will terminate immediately prior to the consummation of such Reorganization Event unless exercised by the Participant (to the extent then exercisable) within a specified period following the date of such notice, (iii) provide that outstanding Awards shall become exercisable, realizable, or deliverable, or restrictions applicable to an Award shall lapse, in whole or in part prior to or upon such Reorganization Event, (iv) in the event of a Reorganization Event under the terms of which holders of Common Stock will receive upon consummation thereof a cash payment for each share surrendered in the Reorganization Event (the “ Acquisition Price ”), make or provide for a cash payment to Participants with respect to each Award held by a Participant equal to (A) the number of shares of Common Stock subject to the vested portion of the Award (after giving effect to any acceleration of vesting that occurs upon or immediately prior to such Reorganization Event) multiplied by (B) the excess, if any, of (I) the Acquisition Price over (II) the exercise, measurement or purchase price of such Award and any applicable tax withholdings, in exchange for the termination of such Award, (v) provide that, in connection with a liquidation or dissolution of the Company, Awards shall convert into the right to receive liquidation proceeds (if applicable, net of the exercise, measurement or purchase price thereof and any applicable tax

11

withholdings) and (vi) any combination of the foregoing. In taking any of the actions permitted under this Section 11(b)(2), the Board shall not be obligated by the Plan to treat all Awards, all Awards held by a Participant, or all Awards of the same type, identically.

(B) Notwithstanding the terms of Section 11(b)(2)(A), in the case of outstanding Restricted Stock Units that are subject to Section 409A of the Code: (i) if the applicable Restricted Stock Unit agreement provides that the Restricted Stock Units shall be settled upon a “change in control event” within the meaning of Treasury Regulation Section 1.409A-3(i)(5) or in subsequent IRS guidance under Section 409A of the Code (a “Section 409A Change in Control Event”), and the Reorganization Event constitutes a Section 409A Change in Control Event, then no assumption or substitution shall be permitted pursuant to Section 11(b)(2)(A)(i) and the Restricted Stock Units shall instead be settled in accordance with the terms of the applicable Restricted Stock Unit agreement; and (ii) the Board may only undertake the actions set forth in clauses (iii), (iv) or (v) of Section 11(b)(2)(A) if the Reorganization Event constitutes a “change in control event” as defined under Treasury Regulation Section 1.409A-3(i)(5)(i) and such action is permitted or required by Section 409A of the Code; if the Reorganization Event is not a “change in control event” as so defined or such action is not permitted or required by Section 409A of the Code, and the acquiring or succeeding corporation does not assume or substitute the Restricted Stock Units pursuant to clause (i) of Section 11(b)(2)(A), then the unvested Restricted Stock Units shall terminate immediately prior to the consummation of the Reorganization Event without any payment in exchange therefor.

(C) For purposes of Section 11(b)(2)(A)(i), an Award (other than Restricted Stock) shall be considered assumed if, following consummation of the Reorganization Event, such Award confers the right to purchase or receive pursuant to the terms of such Award, for each share of Common Stock subject to the Award immediately prior to the consummation of the Reorganization Event, the consideration (whether cash, securities or other property) received as a result of the Reorganization Event by holders of Common Stock for each share of Common Stock held immediately prior to the consummation of the Reorganization Event (and if holders were offered a choice of consideration, the type of consideration chosen by the holders of a majority of the outstanding shares of Common Stock); provided, however , that if the consideration received as a result of the Reorganization Event is not solely common stock of the acquiring or succeeding corporation (or an affiliate thereof), the Company may, with the consent of the acquiring or succeeding corporation, provide for the consideration to be received upon the exercise or settlement of the Award to consist solely of such number of shares of common stock of the acquiring or succeeding corporation (or an affiliate thereof) that the Board determined to be equivalent in value (as of the date of such determination or another date specified by the Board) to the per share consideration received by holders of outstanding shares of Common Stock as a result of the Reorganization Event.

(3) Consequences of a Reorganization Event on Restricted Stock . Upon the occurrence of a Reorganization Event other than a liquidation or dissolution of the Company, the repurchase and other rights of the Company with respect to outstanding Restricted Stock shall inure to the benefit of the Company’s successor and shall, unless the Board determines otherwise, apply to the cash, securities or other property which the Common Stock was converted into or exchanged for pursuant to such Reorganization Event in the same manner and to the same extent as they applied to such Restricted Stock; provided , however , that the Board may provide for termination or deemed satisfaction of such repurchase or other rights under the instrument evidencing any Restricted Stock or any other agreement between a Participant and the Company, either initially or by amendment. Upon the occurrence of a Reorganization Event involving the liquidation or dissolution of the Company, except

12

to the extent specifically provided to the contrary in the instrument evidencing any Restricted Stock or any other agreement between a Participant and the Company, all restrictions and conditions on all Restricted Stock then outstanding shall automatically be deemed terminated or satisfied.

(c) Change in Control Events .

(1) Definition . A “ Change in Control Event ” shall mean:

(A) the acquisition by an individual, entity or group (within the meaning of Section 13(d)(3) or 14(d)(2) of the Exchange Act) (a “ Person ”) of beneficial ownership of any capital stock of the Company if, after such acquisition, such Person beneficially owns (within the meaning of Rule 13d-3 under the Exchange Act) 50% or more of either (x) the then-outstanding shares of common stock of the Company (the “ Outstanding Company Common Stock ”) or (y) the combined voting power of the then-outstanding securities of the Company entitled to vote generally in the election of directors (the “ Outstanding Company Voting Securities ”); provided, however , that for purposes of this subsection (A), the following acquisitions shall not constitute a Change in Control Event: (1) any acquisition directly from the Company or (2) any acquisition by any entity pursuant to a Business Combination (as defined below) which complies with clauses (x) and (y) of subsection (C) of this definition; or

(B) a change in the composition of the Board that results in the Continuing Directors (as defined below) no longer constituting a majority of the Board (or, if applicable, the Board of Directors of a successor corporation to the Company), where the term “ Continuing Director ” means at any date a member of the Board (x) who was a member of the Board on the date of the initial adoption of the Plan by the Board or (y) who was nominated or elected subsequent to such date by at least a majority of the directors who were Continuing Directors at the time of such nomination or election or whose election to the Board was recommended or endorsed by at least a majority of the directors who were Continuing Directors at the time of such nomination or election; provided, however , that there shall be excluded from this clause (y) any individual whose initial assumption of office occurred as a result of an actual or threatened election contest with respect to the election or removal of directors or other actual or threatened solicitation of proxies or consents, by or on behalf of a person other than the Board; or

(C) the consummation of a merger, consolidation, reorganization, recapitalization or share exchange involving the Company or a sale or other disposition of all or substantially all of the assets of the Company (a “ Business Combination ”), unless, immediately following such Business Combination, each of the following two conditions is satisfied: (x) all or substantially all of the individuals and entities who were the beneficial owners of the Outstanding Company Common Stock and Outstanding Company Voting Securities immediately prior to such Business Combination beneficially own, directly or indirectly, more than 50% of the then-outstanding shares of common stock and the combined voting power of the then-outstanding securities entitled to vote generally in the election of directors, respectively, of the resulting or acquiring corporation in such Business Combination (which shall include, without limitation, a corporation which as a result of such transaction owns the Company or substantially all of the Company’s assets either directly or through one or more subsidiaries) (such resulting or acquiring corporation is referred to herein as the “ Acquiring Corporation ”) in substantially the same proportions as their ownership of the Outstanding Company Common Stock and Outstanding Company Voting Securities, respectively, immediately prior to such Business Combination and (y) no Person (excluding any employee benefit plan (or related trust) maintained or sponsored by the Company or by the Acquiring Corporation) beneficially owns, directly or

13

indirectly, 50% or more of the then-outstanding shares of common stock of the Acquiring Corporation, or of the combined voting power of the then-outstanding securities of such corporation entitled to vote generally in the election of directors (except to the extent that such ownership existed prior to the Business Combination); or

(D) the liquidation or dissolution of the Company.

(2) Effect on Options and SARs . Notwithstanding the provisions of Section 11(b), effective immediately prior to a Change in Control Event, except to the extent specifically provided to the contrary in the instrument evidencing any Option or SAR or any other agreement between a Participant and the Company, all Options and SARs then outstanding shall automatically become immediately exercisable in full.

(3) Effect on Restricted Stock . Notwithstanding the provisions of Section 11(b), effective immediately prior to a Change in Control Event, except to the extent specifically provided to the contrary in the instrument evidencing the Restricted Stock or any other agreement between a Participant and the Company, all restrictions and conditions on all Restricted Stock then-outstanding shall automatically be deemed terminated or satisfied.

(4) Effect on Restricted Stock Units . Notwithstanding the provisions of Section 11(b), effective immediately prior to a Change in Control Event, except to the extent specifically provided to the contrary in the instrument evidencing any Restricted Stock Unit Award or any other agreement between a Participant and the Company, all restrictions and conditions on all Restricted Stock Units then outstanding shall automatically be deemed terminated and satisfied; provided, however, that for any Restricted Stock Units that are not exempt from Section 409A of the Code, if the Change in Control Event does not also constitute a Section 409 Change in Control Event, then the unvested Restricted Stock Units shall be paid out in accordance with the terms provided in the applicable Restricted Stock Unit Award (other than any terms applicable to payment as a result of a change in control event that is not a Section 409A Change in Control Event), provided however that, in lieu of such payment, if required by Section 409A of the Code to avoid imposition of taxes thereunder, any such unvested Restricted Stock Units shall terminate without any payment in exchange therefor.

(5) Effect on Other Stock-Based Awards . The Board may specify in an Award agreement at the time of grant or otherwise the effect of a Change in Control on an Other Stock-Based Award and Cash-Based Award.

(6) Section 409A . The definition of Change in Control Event for purposes of the Plan is intended to conform to a Section 409A Change in Control Event, pursuant to the description of “Change in Control Events” in Treasury Regulation section 1.409A-3(i)(5), or in subsequent IRS guidance describing what constitutes a change in control event for purposes of Section 409A of the Code when the Award is subject to Section 409A. Accordingly, no Change in Control Event will be deemed to provide for acceleration of payment with respect to a transaction or event described in this Section 11(c) unless the transaction or event would constitute a 409A Change in Control Event.

(a) Transferability of Awards . Awards shall not be sold, assigned, transferred, pledged or otherwise encumbered by the person to whom they are granted, either voluntarily or by operation of law, except by will or the laws of descent and distribution or, other than in the case of an Incentive Stock

14

Option, pursuant to a qualified domestic relations order, and, during the life of the Participant, shall be exercisable only by the Participant; provided, however , that the Board may permit or provide in an Award for the gratuitous transfer of the Award by the Participant to or for the benefit of any immediate family member, family trust or other entity established for the benefit of the Participant and/or an immediate family member thereof if the Company would be eligible to use a Form S-8 under the Securities Act for the registration of the sale of the Common Stock subject to such Award to such proposed transferee; provided further , that the Company shall not be required to recognize any such permitted transfer until such time as such permitted transferee shall, as a condition to such transfer, deliver to the Company a written instrument in form and substance satisfactory to the Company confirming that such transferee shall be bound by all of the terms and conditions of the Award. References to a Participant, to the extent relevant in the context, shall include references to authorized transferees. For the avoidance of doubt, nothing contained in this Section 11(a) shall be deemed to restrict a transfer to the Company.

(b) Documentation . Each Award shall be evidenced in such form (written, electronic or otherwise) as the Board shall determine. Each Award may contain terms and conditions in addition to those set forth in the Plan.

(c) Board Discretion . Except as otherwise provided by the Plan, each Award may be made alone or in addition or in relation to any other Award. The terms of each Award need not be identical, and the Board need not treat Participants uniformly.

(d) Termination of Status . The Board shall determine the effect on an Award of the disability, death, termination or other cessation of employment, authorized leave of absence or other change in the employment or other status of a Participant and the extent to which, and the period during which, the Participant, or the Participant’s legal representative, conservator, guardian or Designated Beneficiary, may exercise rights under the Award.

(e) Withholding . The Participant must satisfy all applicable federal, state, and local or other income and employment tax withholding obligations before the Company will deliver stock certificates or otherwise recognize ownership of Common Stock under an Award. The Company may decide to satisfy the withholding obligations through additional withholding on salary or wages. If the Company elects not to or cannot withhold from other compensation, the Participant must pay the Company the full amount, if any, required for withholding or have a broker tender to the Company cash equal to the withholding obligations. Payment of withholding obligations is due before the Company will issue any shares on exercise, vesting or release from forfeiture of an Award or at the same time as payment of the exercise or purchase price, unless the Company determines otherwise. If provided for in an Award or approved by the Board in its sole discretion, a Participant may satisfy such tax obligations in whole or in part by delivery (either by actual delivery or attestation) of shares of Common Stock, including shares retained from the Award creating the tax obligation, valued at their Fair Market Value; provided, however , except as otherwise provided by the Board, that the total tax withholding where stock is being used to satisfy such tax obligations cannot exceed the Company’s minimum statutory withholding obligations (based on minimum statutory withholding rates for federal and state tax purposes, including payroll taxes, that are applicable to such supplemental taxable income). Shares used to satisfy tax withholding requirements cannot be subject to any repurchase, forfeiture, unfulfilled vesting or other similar requirements.

15

(f) Amendment of Award . Except as otherwise provided in Section 5(g) with respect to repricings, or Section 13(d) with respect to actions requiring stockholder approval, the Board may amend, modify or terminate any outstanding Award, including but not limited to, substituting therefor another Award of the same or a different type, changing the date of exercise or realization, and converting an Incentive Stock Option to a Nonstatutory Stock Option. The Participant’s consent to such action shall be required unless (i) the Board determines that the action, taking into account any related action, does not materially and adversely affect the Participant’s rights under the Plan or (ii) the change is permitted under Section 11.

(g) Conditions on Delivery of Stock . The Company will not be obligated to deliver any shares of Common Stock pursuant to the Plan or to remove restrictions from shares previously issued or delivered under the Plan until (i) all conditions of the Award have been met or removed to the satisfaction of the Company, (ii) in the opinion of the Company’s counsel, all other legal matters in connection with the issuance and delivery of such shares have been satisfied, including any applicable securities laws and regulations and any applicable stock exchange or stock market rules and regulations, and (iii) the Participant has executed and delivered to the Company such representations or agreements as the Company may consider appropriate to satisfy the requirements of any applicable laws, rules or regulations.

(h) Acceleration . The Board may at any time provide that any Award shall become immediately exercisable in whole or in part, free of some or all restrictions or conditions, or otherwise realizable in whole or in part, as the case may be.

(a) No Right To Employment or Other Status . No person shall have any claim or right to be granted an Award by virtue of the adoption of the Plan, and the grant of an Award shall not be construed as giving a Participant the right to continued employment or any other relationship with the Company. The Company expressly reserves the right at any time to dismiss or otherwise terminate its relationship with a Participant free from any liability or claim under the Plan, except as expressly provided in the applicable Award.

(b) No Rights As Stockholder . Subject to the provisions of the applicable Award, no Participant or Designated Beneficiary shall have any rights as a stockholder with respect to any shares of Common Stock to be distributed with respect to an Award until becoming the record holder of such shares.

(c) Term of Plan . No Awards shall be granted under the Plan after the expiration of 10 years from the Effective Date, but Awards previously granted may extend beyond that date.

(d) Amendment of Plan . The Board may amend, suspend or terminate the Plan or any portion thereof at any time provided that (i) to the extent required by Section 162(m), no Award granted to a Participant that is intended to comply with Section 162(m) after the date of such amendment shall become exercisable, realizable or vested, as applicable to such Award, unless and until the Company’s stockholders approve such amendment in the manner required by Section 162(m); (ii) no amendment that would require stockholder approval under the rules of the NASDAQ may be made effective unless and until the Company’s stockholders approve such amendment; and (iii) if the NASDAQ amends its corporate governance rules so that such rules no longer require stockholder approval of material amendments to equity compensation plans, then, from and after the effective date of such amendment

16

to the NASDAQ rules, no amendment to the Plan (A) materially increasing the number of shares authorized under the Plan (other than pursuant to Section 4(c) or 11), (B) expanding the types of Awards that may be granted under the Plan, or (C) materially expanding the class of participants eligible to participate in the Plan shall be effective unless and until the Company’s stockholders approve such amendment. In addition, if at any time the approval of the Company’s stockholders is required as to any other modification or amendment under Section 422 of the Code or any successor provision with respect to Incentive Stock Options, the Board may not effect such modification or amendment without such approval. Unless otherwise specified in the amendment, any amendment to the Plan adopted in accordance with this Section 13(d) shall apply to, and be binding on the holders of, all Awards outstanding under the Plan at the time the amendment is adopted, provided the Board determines that such amendment, taking into account any related action, does not materially and adversely affect the rights of Participants under the Plan.

(e) Authorization of Sub-Plans (including for Grants to non-U.S. Employees) . The Board may from time to time establish one or more sub-plans under the Plan for purposes of satisfying applicable securities, tax or other laws of various jurisdictions. The Board shall establish such sub-plans by adopting supplements to the Plan containing (i) such limitations on the Board’s discretion under the Plan as the Board deems necessary or desirable or (ii) such additional terms and conditions not otherwise inconsistent with the Plan as the Board shall deem necessary or desirable. All supplements adopted by the Board shall be deemed to be part of the Plan, but each supplement shall apply only to Participants within the affected jurisdiction and the Company shall not be required to provide copies of any supplement to Participants in any jurisdiction which is not the subject of such supplement.

(f) Compliance with Section 409A of the Code . Except as provided in individual Award agreements initially or by amendment, if and to the extent any portion of any payment, compensation or other benefit provided to a Participant in connection with his or her employment termination is determined to constitute “nonqualified deferred compensation” within the meaning of Section 409A of the Code and the Participant is a specified employee as defined in Section 409A(a)(2)(B)(i) of the Code, as determined by the Company in accordance with its procedures, by which determination the Participant (through accepting the Award) agrees that he or she is bound, such portion of the payment, compensation or other benefit shall not be paid before the day that is six months plus one day after the date of “separation from service” (as determined under Section 409A of the Code) (the “ New Payment Date ”), except as Section 409A of the Code may then permit. The aggregate of any payments that otherwise would have been paid to the Participant during the period between the date of separation from service and the New Payment Date shall be paid to the Participant in a lump sum on such New Payment Date, and any remaining payments will be paid on their original schedule.

The Company makes no representations or warranty and shall have no liability to the Participant or any other person if any provisions of or payments, compensation or other benefits under the Plan are determined to constitute nonqualified deferred compensation subject to Section 409A of the Code but do not to satisfy the conditions of that section.

(g) Limitations on Liability . Notwithstanding any other provisions of the Plan, no individual acting as a director, officer, employee or agent of the Company will be liable to any Participant, former Participant, spouse, beneficiary, or any other person for any claim, loss, liability, or expense incurred in connection with the Plan, nor will such individual be personally liable with respect to the Plan because of any contract or other instrument he or she executes in his or her capacity as a director, officer, employee or agent of the Company. The Company will indemnify and hold harmless each director,

17

officer, employee or agent of the Company to whom any duty or power relating to the administration or interpretation of the Plan has been or will be delegated, against any cost or expense (including attorneys’ fees) or liability (including any sum paid in settlement of a claim with the Board’s approval) arising out of any act or omission to act concerning the Plan unless arising out of such person’s own fraud or bad faith.

(h) Governing Law . The provisions of the Plan and all Awards made hereunder shall be governed by and interpreted in accordance with the laws of the State of Delaware, excluding choice-of-law principles of the law of such state that would require the application of the laws of a jurisdiction other than the State of Delaware.

18

AMENDMENT NO. 1 TO

INFINITY PHARMACEUTICALS, INC.

2010 STOCK INCENTIVE PLAN

The Infinity Pharmaceuticals, Inc. 2010 Stock Incentive Plan be and hereby is amended by deleting Sections 6(a), 6(b) and 6(c) in their entirety and replacing them with the following:

*    *    *

(a) Initial Grant . Upon the commencement of service on the Board by any individual who is not then an employee of the Company or any subsidiary of the Company, such person shall automatically be granted a Nonstatutory Stock Option to purchase 10,000 shares of Common Stock (subject to adjustment under Section 6(e), 6(f) or 11).

(b) Annual Grant . On the date of each annual meeting of stockholders of the Company, each member of the Board of Directors of the Company who is both serving as a director of the Company immediately prior to and immediately following such annual meeting and who is not then an employee of the Company or any of its subsidiaries, shall automatically be granted a Nonstatutory Stock Option to purchase 6,000 shares of Common Stock (subject to adjustment under Section 6(e), 6(f) or 11); provided, however , that a director shall not be eligible to receive an option grant under this Section 6(b) unless such director served on the Board on the last day of the immediately preceding calendar year.

(c) Additional Grants . Upon the commencement of service in the following positions by any individual who is not then an employee of the Company or any of its subsidiaries, and each anniversary thereafter that such individual is continuing to serve in such position, such person shall automatically be granted a Nonstatutory Stock Option to purchase the number of shares of Common Stock (subject to adjustment under Section 6(e), 6(f) or 11) indicated below:

(1) if the individual serves as chair of the Board, a Nonstatutory Stock Option to purchase 12,000 shares of Common Stock;

(2) if the individual serves as lead outside director of the Board, a Nonstatutory Stock Option to purchase 10,000 shares of Common Stock;

(3) if the individual serves as chair of the research and development committee of the Board, a Nonstatutory Stock Option to purchase 4,000 shares of Common Stock;

(4) if the individual serves as chair of the audit committee of the Board, a Nonstatutory Stock Option to purchase 4,000 shares of Common Stock;

(5) if the individual serves as chair of the compensation committee of the Board, a Nonstatutory Stock Option to purchase 2,000 shares of Common Stock; and

(6) if the individual serves as the chair of the nominating and corporate governance committee of the Board, if such individual is not also lead outside director of the board, a Nonstatutory Stock Option to purchase 2,000 shares of Common Stock.

Approved by the Board of Directors – 10 December 2010

AMENDMENT NO. 2 TO

INFINITY PHARMACEUTICALS, INC.

2010 STOCK INCENTIVE PLAN

The 2010 Stock Incentive Plan, as amended (the “Plan”) of Infinity Pharmaceuticals, Inc. is hereby amended as follows:

Section 4(a)(1) of the Plan is hereby deleted and a new Section 4(a)(1) is inserted in lieu thereof which shall read as follows:

“(1) Authorized Number of Shares . Subject to adjustment under Section 11, Awards may be made under the Plan for up to 6,000,000 shares of common stock, $.001 par value per share, of the Company (the “ Common Stock ”), any or all of which Awards may be in the form of Incentive Stock Options (as defined in Section 5(b)). Shares issued under the Plan may consist in whole or in part of authorized but unissued shares or treasury shares. The Company shall not make any new Awards under any prior equity plans after the date the Plan is approved by the Company’s stockholders (the “Effective Date” ).”

Except as set forth above, the remainder of the Plan remains in full force and effect.

Approved by the Board of Directors – 8 March 2012

Approved by the Stockholders – 16 May 2012

AMENDMENT NO. 3 TO

2010 STOCK INCENTIVE PLAN

OF

INFINITY PHARMACEUTICALS, INC.

The 2010 Stock Incentive Plan, as amended (the “Plan”) of Infinity Pharmaceuticals, Inc. is hereby amended as follows:

1. Sections 6(a), (b), (c) and (d) of the Plan are hereby deleted and new Sections 6(a), (b), (c) and (d) are inserted in lieu thereof which shall read as follows:

“(a) Initial Grant . Upon the commencement of service on the Board by any individual who is not then an employee of the Company or any subsidiary of the Company, such person shall automatically be granted a Nonstatutory Stock Option to purchase 30,000 shares of Common Stock (subject to adjustment under Section 6(e), 6(f) or 11).

(b) Annual Grant . On the date of each annual meeting of stockholders of the Company, each member of the Board of Directors of the Company who is both serving as a director of the Company immediately prior to and immediately following such annual meeting and who is not then an employee of the Company or any of its subsidiaries, shall automatically be granted a Nonstatutory Stock Option to purchase 15,000 shares of Common Stock (subject to adjustment under Section 6(e), 6(f) or 11); provided, however, that a director shall not be eligible to receive an option grant under this Section 6(b) unless such director served on the Board on the last day of the immediately preceding calendar year.

(c) Additional Grants . Upon the commencement of service in the following positions by any individual who is not then an employee of the Company or any of its subsidiaries, and each anniversary thereafter that such individual is continuing to serve in such position, such person shall automatically be granted a Nonstatutory Stock Option to purchase the number of shares of Common Stock (subject to adjustment under Section 6(e), 6(f) or 11) indicated below:

(1) if the individual serves as chair of the Board, a Nonstatutory Stock Option to purchase 12,000 shares of Common Stock;

(2) if the individual serves as lead outside director of the Board and is not also chair of the Board, a Nonstatutory Stock Option to purchase 10,000 shares of Common Stock;

(3) if the individual serves as chair of the research and development committee of the Board, a Nonstatutory Stock Option to purchase 4,000 shares of Common Stock;

(4) if the individual serves as chair of the audit committee of the Board, a Nonstatutory Stock Option to purchase 4,000 shares of Common Stock;

(5) if the individual serves as chair of the compensation committee of the Board, a Nonstatutory Stock Option to purchase 2,000 shares of Common Stock; and

(6) if the individual serves as the chair of the nominating and corporate governance committee of the Board, if such individual is not also lead outside director of the board, a Nonstatutory Stock Option to purchase 2,000 shares of Common Stock.

(d) Terms of Director Options . Options granted under this Section 6 shall (i) have an exercise price equal to the closing sale price (for the primary trading session) of the Common Stock on the national securities exchange on which the Common Stock is then traded on the date of grant (or if the date of grant is not a trading day on such exchange, the trading day immediately prior to the date of grant) or, if the Common Stock is not then traded on a national securities exchange, the Fair Market Value of the Common Stock, (ii) vest in equal quarterly installments (with respect to one-eighth (1/8 ^th ) of the shares subject to the option grant in the case of Initial Grants under Section 6(a) and with respect to one-fourth (1/4 ^th ) of the shares subject to the option grant in the case of Annual Grants and Additional Grants under Sections 6(b) and (c), respectively) on the last day of each calendar quarter provided that the individual is serving on the Board or in the positions listed in Section 6(c), as applicable, on such date, provided that no additional vesting shall take place after the Participant ceases to serve as a director and further provided that the Options granted under this Section 6 shall immediately vest in the case of death, disability or change in control, (iii) expire on the earlier of 10 years from the date of grant or one year following cessation of service on the Board and (iv) contain such other terms and conditions as the Board shall determine.”

Except as set forth above, the remainder of the Plan remains in full force and effect.

Adopted by the Board of Directors on March 6, 2013.

AMENDMENT NO. 4 TO

2010 STOCK INCENTIVE PLAN

OF

INFINITY PHARMACEUTICALS, INC.

The 2010 Stock Incentive Plan, as amended (the “Plan”) of Infinity Pharmaceuticals, Inc. is hereby amended as follows:

1. Section 4(a)(1) of the Plan is hereby deleted and a new Section 4(a)(1) is inserted in lieu thereof which shall read as follows:

“(1) Authorized Number of Shares . Subject to adjustment under Section 11, Awards may be made under the Plan for up to 7,485,000 shares of common stock, $.001 par value per share, of the Company (the “ Common Stock ”), any or all of which Awards may be in the form of Incentive Stock Options (as defined in Section 5(b)). Shares issued under the Plan may consist in whole or in part of authorized but unissued shares or treasury shares. The Company shall not make any new Awards under any prior equity plans after the date the Plan is approved by the Company’s stockholders (the “Effective Date” ).”

Except as set forth above, the remainder of the Plan remains in full force and effect.

Adopted by the Board of Directors on March 6, 2013.

Approved by the stockholders on June 11, 2013.

AMENDMENT NO. 5 TO

2010 STOCK INCENTIVE PLAN

OF

INFINITY PHARMACEUTICALS, INC.

The 2010 Stock Incentive Plan, as amended (the “Plan”) of Infinity Pharmaceuticals, Inc. is hereby amended as follows:

“(1) Authorized Number of Shares . Subject to adjustment under Section 11, Awards may be made under the Plan for up to 9,785,000 shares of common stock, $.001 par value per share, of the Company (the “ Common Stock ”), any or all of which Awards may be in the form of Incentive Stock Options (as defined in Section 5(b)). Shares issued under the Plan may consist in whole or in part of authorized but unissued shares or treasury shares. The Company shall not make any new Awards under any prior equity plans after the date the Plan is approved by the Company’s stockholders (the “Effective Date” ).”

Except as set forth above, the remainder of the Plan remains in full force and effect.

Approved by the Board of Directors – 19 March 2015

Approved by the Stockholders – 15 June 2015