Amended and Restated Investors Rights Agreement, dated January 22, 2021, by and among the Registrant and the other parties thereto

Exhibit 4.2

THESEUS PHARMACEUTICALS, INC.

AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT

January 22, 2021

TABLE OF CONTENTS

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AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT

This AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT (the “Agreement”) is made as of January 22, 2021, by and among THESEUS PHARMACEUTICALS, INC., a Delaware corporation (the “Company”), and the investors listed on Schedule A hereto, each of which is herein referred to as an “Investor” and collectively as the “Investors”.

RECITALS

WHEREAS, the Company and the Investors are parties to that certain Series B Preferred Stock Purchase Agreement of even date herewith (the “Series B Agreement”) which provides for, among other things, the purchase by such Investors of shares of the Company’s Series B Preferred Stock, par value $0.0001 per share (the “Series B Preferred Stock”);

WHEREAS, the Company and the holders of the Company’s Series A Preferred Stock, par value $0.0001 per share (the “Series A Preferred Stock” and together with the Series B Preferred Stock, the “Preferred Stock”) have previously entered into that certain Investors’ Rights Agreement dated as of February 7, 2018 (the “Prior Agreement”) and desire to amend and restate the Prior Agreement to accept the rights created pursuant hereto in lieu of the rights created under the Prior Agreement; and

WHEREAS, in order to induce certain of the Investors to enter into the Series B Agreement and purchase shares of Series B Preferred Stock thereunder, the Company and the holders of Series A Preferred Stock desire to enter into this Agreement with such Investors.

NOW, THEREFORE, THE PARTIES HEREBY AGREE AS FOLLOWS:

(a) The term “Act” means the Securities Act of 1933, as amended, and the rules and regulations promulgated thereunder.

(b) The term “Affiliate” means, with respect to any Person, any other Person who or which, directly or indirectly, controls, is controlled by, or is under common control with such specified Person, including, without limitation, any general partner, officer, director or manager of such Person and any venture capital or other investment fund now or hereafter existing that is controlled by one or more general partners or managing members of, or is under common investment management with, such Person.

(c) The term “Board” means the Company’s Board of Directors, as constituted from time to time.

(d) The term “Direct Listing” means the Company’s initial listing of its Common Stock on a national securities exchange by means of an effective registration statement on Form S-1 filed by the Company with the Securities and Exchange Commission. For the avoidance of doubt, a Direct Listing shall not be deemed to be an underwritten public offering of the Company’s Common Stock registered under the Act. Any and all mentions of an underwritten offering or underwriters contained herein shall not apply to a Direct Listing.

(e) The term “Excluded Registration” means (i) a registration relating solely to the sale of securities of participants in a Company stock plan, (ii) a registration relating to a corporate reorganization or transaction under Rule 145 of the Act, (iii) a registration on any form that does not include substantially the same information as would be required to be included in a registration statement covering the sale of the Registrable Securities, or (iv) a registration in which the only Common Stock being registered is Common Stock issuable upon conversion of debt securities that are also being registered.

(f) The term “Form S-3” means such form under the Act as in effect on the date hereof or any registration form under the Act subsequently adopted by the SEC that permits inclusion or incorporation of substantial information by reference to other documents filed by the Company with the SEC.

(g) The term “Free Writing Prospectus” means a free-writing prospectus, as defined in Rule 405.

(h) The term “Holder” means any Person owning or having the right to acquire Registrable Securities or any assignee thereof in accordance with Section 2.10 of this Agreement.

(i) The term “Initial Offering” means the Company’s first Offering if the Company has not previously effected a Direct Listing.

(j) The term “1934 Act” means the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder.

(k) The term “Offering” means the Company’s firm commitment underwritten public offering of its Common Stock or other equity securities to the public under the Act.

(l) The term “Person” shall mean any individual, corporation, partnership, trust, limited liability company, association or other entity.

(m) The terms “register,” “registered,” and “registration” refer to a registration effected by preparing and filing a registration statement or similar document in compliance with the Act, and the declaration or ordering of effectiveness of such registration statement or document.

(n) The term “Registrable Securities” means (i) the Common Stock issuable or issued upon conversion of the Preferred Stock, (ii) Common Stock, or Common Stock issuable upon the conversion and/or exercise of any other securities of the Company, acquired by Investors after the date hereof; and (iii) the Common Stock issued as (or issuable upon the conversion or exercise of any warrant, right or other security that is issued as) a dividend or other distribution with respect to, or in exchange for, or in replacement of, the shares referenced in (i) and (ii) above, excluding in all cases, however, any Registrable Securities sold

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by a Person in a transaction in which his rights under Section 2 of this Agreement are not assigned. In addition, the number of shares of Registrable Securities outstanding shall equal the aggregate of the number of shares of Common Stock outstanding that are, and the number of shares of Common Stock issuable pursuant to then exercisable or convertible securities that are, Registrable Securities.

(o) The term “Restated Certificate” shall mean the Company’s Restated Certificate of Incorporation, as amended and/or restated from time to time.

(p) The term “Restricted Securities” shall mean the securities of the Company required to be notated with the legend set forth in Subsection 2.13(c) hereof.

(q) The term “Rule 144” shall mean Rule 144 under the Act.

(r) The term “Rule 144(b)(1)(i)” shall mean subsection (b)(1)(i) of Rule 144 under the Act as it applies to Persons who have held shares for more than one (1) year.

(s) The term “Rule 405” shall mean Rule 405 under the Act.

(t) The term “SEC” shall mean the Securities and Exchange Commission.

2.1 Request for Registration.

(a) Subject to the conditions of this Section 2.1, if the Company shall receive at any time after the earlier of (i) five (5) years after the date of this Agreement or (ii) six (6) months after the effective date of the Initial Offering or a Direct Listing, a written request from the Holders of at least fifty percent (50%) of the Registrable Securities then outstanding (for purposes of this Section 2.1, the “Initiating Holders”) that the Company file a registration statement under the Act covering the registration of Registrable Securities with an anticipated aggregate offering price of at least $15,000,000, then the Company shall, within twenty (20) days of the receipt thereof, give written notice of such request to all Holders, and subject to the limitations of this Section 2.1, use its commercially reasonable efforts to effect, as soon as practicable, the registration under the Act of all Registrable Securities that the Holders request to be registered in a written request received by the Company within twenty (20) days of the mailing of the Company’s notice pursuant to this Section 2.1(a).

(b) If the Initiating Holders intend to distribute the Registrable Securities covered by their request by means of an underwriting, they shall so advise the Company as a part of their request made pursuant to this Section 2.1, and the Company shall include such information in the written notice referred to in Section 2.1(a). In such event the right of any Holder to include its Registrable Securities in such registration shall be conditioned upon such Holder’s participation in such underwriting and the inclusion of such Holder’s Registrable Securities in the underwriting (unless otherwise mutually agreed by a majority in interest of the Initiating Holders and such Holder) to the extent provided herein. All Holders proposing to distribute their securities through such underwriting shall enter into an underwriting

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agreement in customary form with the underwriter or underwriters selected for such underwriting by the Company (which underwriter or underwriters shall be reasonably acceptable to those Initiating Holders holding a majority of the Registrable Securities then held by all Initiating Holders). Notwithstanding any other provision of this Section 2.1, if the underwriter advises the Company that marketing factors require a limitation on the number of securities underwritten (including Registrable Securities), then the Company shall so advise all Holders of Registrable Securities that would otherwise be underwritten pursuant hereto, and the number of shares that may be included in the underwriting shall be allocated to the Holders of such Registrable Securities pro rata based on the number of Registrable Securities held by all such Holders (including the Initiating Holders). In no event shall any Registrable Securities be excluded from such underwriting unless all other securities are first excluded. Any Registrable Securities excluded or withdrawn from such underwriting shall be withdrawn from the registration.

(c) Notwithstanding the foregoing, the Company shall not be required to effect a registration pursuant to this Section 2.1:

(i) in any particular jurisdiction in which the Company would be required to execute a general consent to service of process in effecting such registration, unless the Company is already subject to service in such jurisdiction and except as may be required under the Act; or

(ii) after the Company has effected two (2) registrations pursuant to this Section 2.1, and such registrations have been declared or ordered effective; or

(iii) during the period starting with the date sixty (60) days prior to the Company’s good faith estimate of the date of the filing of and ending on a date one hundred eighty (180) days following the effective date of a Company-initiated registration subject to Section 2.2 below, provided that the Company is actively employing in good faith its commercially reasonable efforts to cause such registration statement to become effective; or

(iv) if the Initiating Holders propose to dispose of Registrable Securities that may be registered on Form S-3 pursuant to Section 2.3 hereof; or

(v) if the Company shall furnish to Holders requesting a registration statement pursuant to this Section 2.1 a certificate signed by the Company’s Chief Executive Officer or Chairman of the Board of Directors stating that in the good faith judgment of the Board, it would be seriously detrimental to the Company and its stockholders for such registration statement to be effected or remain effective at such time, in which event the Company shall have the right to defer such filing for a period of not more than one hundred twenty (120) days after receipt of the request of the Initiating Holders; provided that such right shall be exercised by the Company not more than once in any twelve (12) month period.

2.2 Company Registration.

(a) If (but without any obligation to do so) the Company proposes to register (including for this purpose a registration effected by the Company for stockholders other than the Holders) any of its stock or other securities under the Act in connection with the public offering of such securities solely for cash (other than (i) a registration relating to a demand

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pursuant to Section 2.1 of this Agreement or (ii) an Excluded Registration), the Company shall, at such time, promptly give each Holder written notice of such registration. Upon the written request of each Holder given within twenty (20) days after mailing of such notice by the Company in accordance with Section 4.5 of this Agreement, the Company shall, subject to the provisions of Section 2.2(c) of this Agreement, use its commercially reasonable efforts to cause to be registered under the Act all of the Registrable Securities that each such Holder requests to be registered.

(b) Right to Terminate Registration. The Company shall have the right to terminate or withdraw any registration initiated by it under this Section 2.2 prior to the effectiveness of such registration whether or not any Holder has elected to include securities in such registration. The expenses of such withdrawn registration shall be borne by the Company in accordance with Section 2.6 hereof.

(c) Underwriting Requirements. In connection with any offering involving an underwriting of shares of the Company’s capital stock, the Company shall not be required under this Section 2.2 to include any of the Holders’ securities in such underwriting unless they accept the terms of the underwriting as agreed upon between the Company and the underwriters selected by the Company (or by other Persons entitled to select the underwriters) and enter into an underwriting agreement in customary form with such underwriters, and then only in such quantity as the underwriters determine in their sole discretion will not jeopardize the success of the offering by the Company. If the total amount of securities, including Registrable Securities, requested by stockholders to be included in such offering exceeds the amount of securities sold other than by the Company that the underwriters determine in their sole discretion is compatible with the success of the offering, then the Company shall be required to include in the offering only that number of such securities, including Registrable Securities, that the underwriters determine in their sole discretion will not jeopardize the success of the offering. In the event that the underwriters determine that less than all of the Registrable Securities requested to be registered can be included in such offering, then the Registrable Securities that are included in such offering shall be apportioned pro rata among the selling Holders based on the number of Registrable Securities held by all selling Holders or in such other proportions as shall mutually be agreed to by all such selling Holders. Notwithstanding the foregoing, in no event shall (i) any Registrable Securities be excluded from such offering unless all other stockholders’ securities have been first excluded from the offering and (ii) the amount of securities of the selling Holders included in the offering be reduced below thirty percent (30%) of the total amount of securities included in such offering, unless such offering is the Initial Offering, in which case the selling Holders may be excluded if the underwriters make the determination described above and no other stockholder’s securities are included in such offering. For purposes of the preceding sentence concerning apportionment, for any selling stockholder that is a Holder of Registrable Securities and that is a venture capital fund, partnership or corporation, the affiliated venture capital funds, partners, members, retired partners, Affiliates and stockholders of such Holder, or the estates and family members of any such partners, members and retired partners and any trusts for the benefit of any of the foregoing Persons shall be deemed to be a single “selling Holder,” and any pro rata reduction with respect to such “selling Holder” shall be based upon the aggregate amount of Registrable Securities owned by all such related entities and individuals.

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2.3 Form S-3 Registration. In case the Company shall receive from the Holders of at least twenty percent (20%) of the Registrable Securities (for purposes of this Section 2.3, the “S-3 Initiating Holders”) a written request or requests that the Company effect a registration on Form S-3 and any related qualification or compliance with respect to all or a part of the Registrable Securities owned by such Holder or Holders, the Company shall:

(a) promptly give written notice of the proposed registration, and any related qualification or compliance, to all other Holders; and

(b) use its commercially reasonable efforts to effect, as soon as practicable, and in no event later than forty-five (45) days after the date the request is given by the S-3 Initiating Holders, such registration and all such qualifications and compliances as may be so requested and as would permit or facilitate the sale and distribution of all or such portion of such Holders’ Registrable Securities as are specified in such request, together with all or such portion of the Registrable Securities of any other Holders joining in such request as are specified in a written request given within fifteen (15) days after receipt of such written notice from the Company; provided, however, that the Company shall not be obligated to effect any such registration, qualification or compliance, pursuant to this Section 2.3:

(i) if Form S-3 is not available for such offering by the Holders;

(ii) if the Holders, together with the holders of any other securities of the Company entitled to inclusion in such registration, propose to sell Registrable Securities and such other securities (if any) at an aggregate price to the public (net of any underwriters’ discounts or commissions) of less than $10,000,000;

(iii) if the Company shall furnish to all Holders requesting a registration statement pursuant to this Section 2.3 a certificate signed by the Company’s Chief Executive Officer or Chairman of the Board of Directors stating that in the good faith judgment of the Board, it would be seriously detrimental to the Company and its stockholders for such registration statement to be effected at such time, in which event the Company shall have the right to defer such filing for a period of not more than ninety (90) days after receipt of the request of the S-3 Initiating Holders; provided that such right shall be exercised by the Company not more than once in any twelve (12) month period; and provided further that the Company shall not register any securities for the account of itself or any other stockholder during such ninety (90) day period (other than an Excluded Registration);

(iv) if the Company has, within the twelve (12) month period preceding the date of such request, already effected two (2) registrations on Form S-3 pursuant to this Section 2.3;

(v) in any particular jurisdiction in which the Company would be required to qualify to do business or to execute a general consent to service of process in effecting such registration, qualification or compliance;

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(vi) if the Company, within thirty (30) days of receipt of the request of such S-3 Initiating Holders, gives notice of its bona fide intention to effect the filing of a registration statement with the SEC within one hundred twenty (120) days of receipt of such request (other than an Excluded Registration (but excluding from this exception a registration specified in clause (iii) of the definition of Excluded Registration), provided that the Company is actively employing in good faith its commercially reasonable efforts to cause such registration statement to become effective; or

(vii) during the period starting with the date thirty (30) days prior to the Company’s good faith estimate of the date of the filing of and ending on a date ninety (90) days following the effective date of a Company-initiated registration subject to Section 2.2 of this Agreement, provided that the Company is actively employing in good faith its commercially reasonable efforts to cause such registration statement to become effective.

(c) If the S-3 Initiating Holders intend to distribute the Registrable Securities covered by their request by means of an underwriting, they shall so advise the Company as a part of their request made pursuant to this Section 2.3 and the Company shall include such information in the written notice referred to in Section 2.3(a). The provisions of Section 2.1(b) of this Agreement shall be applicable to such request (with the substitution of Section 2.3 for references to Section 2.1).

(d) Subject to the foregoing, the Company shall file a registration statement covering the Registrable Securities and other securities so requested to be registered as soon as practicable after receipt of the request or requests of the S-3 Initiating Holders. Registrations effected pursuant to this Section 2.3 shall not be counted as requests for registration effected pursuant to Section 2.1 of this Agreement.

2.4 Obligations of the Company. Whenever required under this Section 2 to effect the registration of any Registrable Securities, the Company shall, as expeditiously as reasonably possible:

(a) prepare and file with the SEC a registration statement with respect to such Registrable Securities and use its commercially reasonable efforts to cause such registration statement to become effective, and, upon the request of the Holders of a majority of the Registrable Securities registered thereunder, keep such registration statement effective for a period of up to one hundred twenty (120) days or, if earlier, until the distribution contemplated in the Registration Statement has been completed;

(b) prepare and file with the SEC such amendments and supplements to such registration statement and the prospectus used in connection with such registration statement as may be necessary to comply with the provisions of the Act with respect to the disposition of all securities covered by such registration statement;

(c) furnish to the Holders such number of copies of a prospectus, including a preliminary prospectus and any Free Writing Prospectus, in conformity with the requirements of the Act, and such other documents as they may reasonably request in order to facilitate the disposition of Registrable Securities owned by them;

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(d) use its commercially reasonable efforts to register and qualify the securities covered by such registration statement under such other securities or Blue Sky laws of such jurisdictions as shall be reasonably requested by the Holders, provided that the Company shall not be required in connection therewith or as a condition thereto to qualify to do business or to file a general consent to service of process in any such states or jurisdictions;

(e) in the event of any underwritten public offering, enter into and perform its obligations under an underwriting agreement, in usual and customary form, with the managing underwriter of such offering;

(f) notify each Holder of Registrable Securities covered by such registration statement at any time when a prospectus or Free Writing Prospectus (to the extent prepared by or on behalf of the Company) relating thereto is required to be delivered under the Act of the happening of any event as a result of which the prospectus included in such registration statement, as then in effect, includes an untrue statement of a material fact or omits to state a material fact required to be stated therein or necessary to make the statements therein not misleading in the light of the circumstances then existing, and, at the request of any such Holder, the Company will, as soon as reasonably practicable, file and furnish to all such Holders a supplement or amendment to such prospectus or Free Writing Prospectus (to the extent prepared by or on behalf of the Company) so that, as thereafter delivered to the purchasers of such Registrable Securities, such prospectus will not contain an untrue statement of a material fact or omit to state any fact necessary to make the statements therein not misleading in light of the circumstances under which they were made;

(g) cause all such Registrable Securities registered pursuant to this Section 2 to be listed on a national exchange or trading system and on each securities exchange and trading system on which similar securities issued by the Company are then listed;

(h) provide a transfer agent and registrar for all Registrable Securities registered pursuant to this Agreement and a CUSIP number for all such Registrable Securities, in each case not later than the effective date of such registration

(i) promptly make available for inspection by the selling Holders, any underwriter participating in any disposition pursuant to such registration statement, and any attorney or accountant or other agent retained by any such underwriter or selected by the selling Holders, all financial and other records, pertinent corporate documents, and properties of the Company, and cause the Company’s officers, directors, employees, and independent accountants to supply all information reasonably requested by any such seller, underwriter, attorney, accountant, or agent, in each case, as necessary or advisable to verify the accuracy of the information in such registration statement and to conduct appropriate due diligence in connection therewith;

(j) notify each selling Holder, promptly after the Company receives notice thereof, of the time when such registration statement has been declared effective or a supplement to any prospectus forming a part of such registration statement has been filed; and

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(k) after such registration statement becomes effective, notify each selling Holder of any request by the SEC that the Company amend or supplement such registration statement or prospectus.

Notwithstanding the provisions of this Section 2, the Company shall be entitled to postpone or suspend, for a reasonable period of time, the filing, effectiveness or use of, or trading under, any registration statement if the Company shall determine that any such filing or the sale of any securities pursuant to such registration statement would in the good faith judgment of the Board:

(i) materially impede, delay or interfere with any material pending or proposed financing, acquisition, corporate reorganization or other similar transaction involving the Company for which the Board has authorized negotiations;

(ii) materially and adversely impair the consummation of any pending or proposed material offering or sale of any class of securities by the Company; or

(iii) require disclosure of material nonpublic information that, if disclosed at such time, would be materially harmful to the interests of the Company and its stockholders; provided, however, that during any such period all executive officers and directors of the Company are also prohibited from selling securities of the Company (or any security of any of the Company’s subsidiaries or Affiliates).

In the event of the suspension of effectiveness of any registration statement pursuant to this Section 2.4, the applicable time period during which such registration statement is to remain effective shall be extended by that number of days equal to the number of days the effectiveness of such registration statement was suspended.

2.5 Information from Holder. It shall be a condition precedent to the obligations of the Company to take any action pursuant to this Section 2 with respect to the Registrable Securities of any selling Holder that such Holder shall furnish to the Company such information regarding itself, the Registrable Securities held by it, and the intended method of disposition of such securities as shall be reasonably required to effect the registration of such Holder’s Registrable Securities.

2.6 Expenses of Registration. All expenses other than underwriting discounts and commissions incurred in connection with registrations, filings or qualifications pursuant to Sections 2.1, 2.2 and 2.3 of this Agreement, including, without limitation, all registration, filing and qualification fees, printers’ and accounting fees, fees and disbursements of counsel for the Company and the reasonable fees and disbursements of one counsel for the selling Holders shall be borne by the Company. Notwithstanding the foregoing, the Company shall not be required to pay for any expenses of any registration proceeding begun pursuant to Section 2.1 or Section 2.3 of this Agreement if the registration request is subsequently withdrawn at the request of the Holders of a majority of the Registrable Securities to be registered (in which case all participating Holders shall bear such expenses pro rata based upon the number of Registrable Securities that were to be included in the withdrawn registration); provided, however, that if at the time of such withdrawal, the Holders have learned of a material adverse change in the

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condition, business or prospects of the Company from that known to the Holders at the time of their request and have withdrawn the request with reasonable promptness following disclosure by the Company of such material adverse change, then the Holders shall not be required to pay any of such expenses and shall retain their rights pursuant to Sections 2.1 and 2.3 of this Agreement.

2.7 Delay of Registration. No Holder shall have any right to obtain or seek an injunction restraining or otherwise delaying any such registration as the result of any controversy that might arise with respect to the interpretation or implementation of this Section 2.

2.8 Indemnification. In the event any Registrable Securities are included in a registration statement under this Section 2:

(a) To the extent permitted by law, the Company will indemnify and hold harmless each Holder, the partners, members, Affiliates, officers, directors and stockholders of each Holder, legal counsel and accountants for each Holder, any underwriter (as defined in the Act) for such Holder and each Person, if any, who controls such Holder or underwriter within the meaning of the Act or the 1934 Act, against any losses, claims, damages or liabilities (joint or several) to which they may become subject under the Act, the 1934 Act, any state securities laws or any rule or regulation promulgated under the Act, the 1934 Act or any state securities laws, insofar as such losses, claims, damages, or liabilities (or actions or proceedings, whether commenced or threatened, in respect thereof) arise out of or are based upon any of the following statements, omissions or violations (collectively, a “Violation”): (i) any untrue or alleged untrue statement of a material fact contained in such registration statement, including any preliminary prospectus, final prospectus, or Free Writing Prospectus contained therein or any amendments or supplements thereto, any issuer information (as defined in Rule 433 of the Act) filed or required to be filed pursuant to Rule 433(d) under the Act or any other document incident to such registration prepared by or on behalf of the Company or used or referred to by the Company, (ii) the omission or alleged omission of a material fact required to be stated in such registration statement, or necessary to make the statements therein not misleading or (iii) any violation or alleged violation by the Company of the Act, the 1934 Act, any state securities laws or any rule or regulation promulgated under the Act, the 1934 Act or any state securities laws, and the Company will reimburse each such Holder, underwriter, controlling Person or other aforementioned Person for any legal or other expenses reasonably incurred by them in connection with investigating or defending any such loss, claim, damage, liability, action or proceeding as such expenses are incurred; provided, however, that the indemnity agreement contained in this Section 2.8(a) shall not apply to amounts paid in settlement of any such loss, claim, damage, liability, action or proceeding if such settlement is effected without the consent of the Company (which consent shall not be unreasonably withheld), nor shall the Company be liable in any such case for any such loss, claim, damage, liability, action or proceeding to the extent that it arises out of or is based upon a Violation that occurs in reliance upon, and in conformity with, written information furnished expressly for use in connection with such registration by any such Holder, underwriter, controlling Person or other aforementioned Person.

(b) To the extent permitted by law, each selling Holder, severally and not jointly, will indemnify and hold harmless the Company, each of its directors, each of its officers who has signed the registration statement, each Person, if any, who controls the

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Company within the meaning of the Act, legal counsel and accountants for the Company, any underwriter, any other Holder selling securities in such registration statement and any controlling Person of any such underwriter or other Holder, against any losses, claims, damages or liabilities (joint or several) to which any of the foregoing Persons may become subject, under the Act, the 1934 Act, any state securities laws or any rule or regulation promulgated under the Act, the 1934 Act or any state securities laws, insofar as such losses, claims, damages or liabilities (or actions or proceedings, whether commenced or threatened, in respect thereof) arise out of or are based upon any Violation, in each case to the extent (and only to the extent) that such Violation occurs in reliance upon and in conformity with written information furnished by such Holder expressly for use in connection with such registration; and each such Holder will reimburse any Person intended to be indemnified pursuant to this Section 2.8(b) for any legal or other expenses reasonably incurred by such Person in connection with investigating or defending any such loss, claim, damage, liability, action or proceeding as such expenses are incurred; provided, however, that the indemnity agreement contained in this Section 2.8(b) shall not apply to amounts paid in settlement of any such loss, claim, damage, liability, action or proceeding if such settlement is effected without the consent of the Holder (which consent shall not be unreasonably withheld), and provided that in no event shall any indemnity under this Section 2.8(b) exceed the net proceeds from the offering received by such Holder, except in the case of fraud of willful misconduct by such Holder.

(c) Promptly after receipt by an indemnified party under this Section 2.8 of notice of the commencement of any action or proceeding (including any governmental action or proceeding) for which a party may be entitled to indemnification, such indemnified party will, if a claim in respect thereof is to be made against any indemnifying party under this Section 2.8, deliver to the indemnifying party a written notice of the commencement thereof and the indemnifying party shall have the right to participate in and, to the extent the indemnifying party so desires, jointly with any other indemnifying party similarly noticed, to assume the defense thereof with counsel mutually satisfactory to the parties; provided, however, that an indemnified party (together with all other indemnified parties that may be represented without conflict by one counsel) shall have the right to retain one (1) separate counsel, with the fees and expenses to be paid by the indemnifying party, if representation of such indemnified party by the counsel retained by the indemnifying party would be inappropriate due to actual or potential differing interests between such indemnified party and any other party represented by such counsel in such proceeding. The failure to deliver written notice to the indemnifying party within a reasonable time of the commencement of any such action or proceeding, if prejudicial to its ability to defend such action or proceeding, shall relieve such indemnifying party of liability to the indemnified party under this Section 2.8 to the extent of such prejudice, but the omission to so deliver written notice to the indemnifying party will not relieve such indemnifying party of any liability that it may have to any indemnified party otherwise than under this Section 2.8.

(d) If the indemnification provided for in this Section 2.8 is held by a court of competent jurisdiction to be unavailable to an indemnified party with respect to any loss, liability, claim, damage or expense referred to herein, then the indemnifying party, in lieu of indemnifying such indemnified party hereunder, shall contribute to the amount paid or payable by such indemnified party as a result of such loss, liability, claim, damage or expense in such proportion as is appropriate to reflect the relative fault of the indemnifying party on the one hand and the indemnified party on the other hand in connection with the statements or omissions that

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resulted in such loss, liability, claim, damage or expense, as well as any other relevant equitable considerations; provided, however, that (i) no contribution by any Holder, when combined with any amounts paid by such Holder pursuant to Section 2.8(b), shall exceed the net proceeds from the offering received by such Holder and (ii) no Person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Act) will be entitled to contribution from any Person who was not guilty of such fraudulent misrepresentation; and provided further that in no event shall a Holder’s liability pursuant to this Section 2.8(d), when combined with the amounts paid or payable by such Holder pursuant to Section 2.8(b), exceed the net proceeds from the offering received by such Holder (net of any expenses paid by such Holder). The relative fault of the indemnifying party and the indemnified party shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the indemnifying party or by the indemnified party and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission.

(e) Notwithstanding the foregoing, to the extent that the provisions on indemnification and contribution contained in the underwriting agreement entered into in connection with the underwritten public offering are in conflict with the foregoing provisions, the provisions in the underwriting agreement shall control.

(f) The obligations of the Company and Holders under this Section 2.8 shall survive the completion of any offering of Registrable Securities in a registration statement under this Section 2 and otherwise.

2.9 Reports Under the 1934 Act. With a view to making available to the Holders the benefits of Rule 144 and any other rule or regulation of the SEC that may at any time permit a Holder to sell securities of the Company to the public without registration or pursuant to a registration on Form S-3, the Company agrees to:

(a) make and keep public information available, as those terms are understood and defined in Rule 144, at all times after the effective date of the Initial Offering;

(b) file with the SEC in a timely manner all reports and other documents required of the Company under the Act and the 1934 Act; and

(c) furnish to any Holder, so long as the Holder owns any Registrable Securities, forthwith upon request (i) a written statement by the Company that it has complied with the reporting requirements of Rule 144 (at any time after ninety (90) days after the effective date of the first registration statement filed by the Company), the Act and the 1934 Act (at any time after it has become subject to such reporting requirements), or that it qualifies as a registrant whose securities may be resold pursuant to Form S-3 (at any time after it so qualifies), (ii) a copy of the most recent annual or quarterly report of the Company and such other reports and documents so filed by the Company and (iii) such other information as may be reasonably requested to avail any Holder of any rule or regulation of the SEC that permits the selling of any such securities without registration or pursuant to such form.

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2.10 Assignment of Registration Rights. The rights to cause the Company to register Registrable Securities pursuant to this Section 2 may be assigned (but only with all related obligations) by a Holder to a transferee or assignee of such securities that (a) is an Affiliate, subsidiary, parent, partner, limited partner, retired partner, member or stockholder of a Holder, (b) is a Holder’s family member or trust for the benefit of an individual Holder or any of such Holder’s family members or (c) after such assignment or transfer, holds at least 500,000 shares of Registrable Securities (appropriately adjusted for any stock split, dividend, combination or other recapitalization), provided: (i) the Company is, within a reasonable time after such transfer, furnished with written notice of the name and address of such transferee or assignee and the securities with respect to which such registration rights are being assigned; (ii) such transferee or assignee agrees in writing to be bound by and subject to the terms and conditions of this Agreement, including, without limitation, the provisions of Section 2.12 of this Agreement; and (iii) such assignment shall be effective only if immediately following such transfer the further disposition of such securities by the transferee or assignee is restricted under the Act.

2.11 Limitations on Subsequent Registration Rights. From and after the date of this Agreement, the Company shall not, without the prior written consent of the Holders holding a majority of the Registrable Securities then held by all Holders, enter into any agreement with any holder or prospective holder of any securities of the Company that would allow such holder or prospective holder (a) to include any of such securities in any registration filed under Section 2.1, Section 2.2 or Section 2.3 of this Agreement, unless under the terms of such agreement, such holder or prospective holder may include such securities in any such registration only to the extent that the inclusion of such securities will not reduce the amount of the Registrable Securities of the Holders that are included or (b) to demand registration of their securities; provided that this limitation shall not apply to any additional Investor who becomes a party to this Agreement in accordance with Subsection 4.10.

2.12 “Market Stand-Off” Agreement.

(a) Each Holder hereby agrees that it will not, without the prior written consent of the managing underwriter, during the period commencing on the date of the final prospectus relating to the Initial Offering and ending on the date specified by the Company and the managing underwriter, such period not to exceed one hundred eighty (180) days (i) lend, offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, or otherwise transfer or dispose of, directly or indirectly, any shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock (whether such shares or any such securities are then owned by the Holder or are thereafter acquired), or (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 the Common Stock, whether any such transaction described in clause (i) or (ii) above is to be settled by delivery of Common Stock or other securities, in cash or otherwise. The foregoing provisions of this Section 2.12 (i) shall apply only to the Initial Offering, (ii) shall not apply to (A) the sale of any shares to an underwriter pursuant to an underwriting agreement, or (B) the transfer of any shares to any trust for the direct or indirect benefit of a Holder or any Family Member of such Holder, provided that the trustee of the trust agrees to be bound in writing by the restrictions set forth herein, and provided, further, that any such transfer shall not

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involve a disposition for value, and (iii) shall only be applicable to the Holders if all officers, directors and greater than one percent (1%) stockholders of the Company enter into similar agreements. Notwithstanding the foregoing, the Company and the managing underwriter may extend the market stand-off period specified above solely to the extent necessary to accommodate regulatory restrictions on (1) the publication or other distribution of research reports, and (2) analyst recommendations and opinions, including, without limitation, the restrictions, if any, contained in FINRA Rule 2241 or any successor provisions or amendments thereto.

(b) The underwriters in connection with the Initial Offering are intended third-party beneficiaries of this Section 2.12 and shall have the right, power and authority to enforce the provisions hereof as though they were a party hereto. Each Holder further agrees to execute such agreements as may be reasonably requested by the underwriters in the Initial Offering that are consistent with this Section 2.12 or that are necessary to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to the Registrable Securities of each Holder (and the shares or securities of every other Person subject to the foregoing restriction) until the end of such period. Any discretionary waiver or termination of the restrictions of any or all of such agreements by the Company or the underwriters shall apply pro rata to all Company stockholders that are subject to such agreements, based on the number of shares subject to such agreements.

2.13 Restrictions on Transfer.

(a) The Preferred Stock and the Registrable Securities or any right or interest therein, shall not be sold, assigned, pledged or in any manner transferred, whether voluntarily or by operation of law, or by gift or otherwise, and the Company shall not recognize and shall issue stop-transfer instructions to its transfer agent with respect to any such sale, pledge or transfer, to any proposed purchaser, pledgee or transferee that is an actual or potential competitor of the Company, as determined in good faith by the Board; provided, however, that (i) any financial investment firm that, together with its Affiliates, holds less than five percent (5%) of the outstanding equity of a competitor of the Company, as determined in good faith by the Board, and does not have (and does not have any Affiliates that have) the right to designate any members of the Board of Directors of any competitor of the Company, as determined in good faith by the Board, shall not be deemed a competitor with respect to this Section 2.13 and (ii) Affiliates of an Investor shall not be deemed competitors for purposes of this Section 2.13(a).

(b) The Preferred Stock and the Registrable Securities shall not be sold, pledged or otherwise transferred, and the Company shall not recognize and shall issue stop-transfer instructions to its transfer agent with respect to any such sale, pledge or transfer, except pursuant to the conditions specified in this Agreement, which conditions are intended to ensure compliance with the provisions of the Act. A transferring Holder will cause any proposed purchaser, pledgee or transferee of the Preferred Stock and the Registrable Securities held by such Holder to agree to take and hold such securities subject to the provisions, and upon the conditions specified in, this Agreement.

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(c) Each certificate, instrument or book entry representing (i) the Preferred Stock, (ii) the Registrable Securities, and (iii) any other securities issued in respect of the securities referenced in clauses (i) and (ii) upon any stock split, stock dividend, recapitalization, merger, consolidation or similar event, shall (unless otherwise permitted by the provisions of Subsection 2.13(d)) be notated with legends substantially in the following form:

“THE SECURITIES REPRESENTED HEREBY HAVE BEEN ACQUIRED FOR INVESTMENT AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED. SUCH SHARES MAY NOT BE SOLD, PLEDGED OR TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR A VALID EXEMPTION FROM THE REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS OF SAID ACT.”

“THE SECURITIES REPRESENTED HEREBY MAY BE TRANSFERRED ONLY IN ACCORDANCE WITH THE TERMS OF AN INVESTORS’ RIGHTS AGREEMENT BETWEEN THE COMPANY AND THE STOCKHOLDER, A COPY OF WHICH IS ON FILE WITH THE SECRETARY OF THE COMPANY.”

(d) The holder of such Restricted Securities, by acceptance of ownership thereof, agrees to comply in all respects with the provisions of this Section 2.13. Before any proposed sale, pledge or transfer of any Restricted Securities, unless there is in effect a registration statement under the Act covering the proposed transaction or following the Initial Offering the transfer is made pursuant to Rule 144, the Holder thereof shall give notice to the Company of such Holder’s intention to effect such sale, pledge or transfer. Each such notice shall describe the manner and circumstances of the proposed sale, pledge or transfer in sufficient detail and, if reasonably requested by the Company, shall be accompanied at such Holder’s expense by either (i) a written opinion of legal counsel who shall, and whose legal opinion shall, be reasonably satisfactory to the Company, addressed to the Company, to the effect that the proposed transaction may be effected without registration under the Act; (ii) a “no action” letter from the SEC to the effect that the proposed sale, pledge or transfer of such Restricted Securities without registration will not result in a recommendation by the staff of the SEC that action be taken with respect thereto; or (iii) any other evidence reasonably satisfactory to counsel to the Company to the effect that the proposed sale, pledge or transfer of the Restricted Securities may be effected without registration under the Act, whereupon the Holder of such Restricted Securities shall be entitled to sell, pledge or transfer such Restricted Securities in accordance with the terms of the notice given by the Holder to the Company. The Company will not require such a legal opinion or “no action” letter (x) in any transaction in compliance with SEC Rule 144; or (y) in any transaction in which such Holder distributes Restricted Securities to an Affiliate of such Holder for no consideration. Each certificate, instrument or book entry representing the Restricted Securities transferred as above provided shall be notated with, except if such transfer is made pursuant to SEC Rule 144, the appropriate restrictive legend set forth in Subsection 2.13(c), except that such certificate, instrument or book entry shall not be notated with such restrictive legend if, in the opinion of counsel for such Holder and the Company, such legend is not required in order to establish compliance with any provisions of the Act.

2.14 Termination of Registration Rights. No Holder shall be entitled to exercise any right provided for in this Section 2: (a) after five (5) years following the consummation of the Initial Offering or a Direct Listing, whichever occurs first, (b) as to any

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Holder, such earlier time after the Initial Offering or a Direct Listing at which such Holder (i) can sell all shares held by it in compliance with Rule 144(b)(1)(i) or (ii) holds one percent (1%) or less of the Company’s outstanding Common Stock and all Registrable Securities held by such Holder (together with any Affiliate of the Holder with whom such Holder must aggregate its sales under Rule 144) can be sold in any three (3) month period without registration in compliance with Rule 144 or (c) after the consummation of a Liquidation Event, as that term is defined in the Restated Certificate.

3.1 Delivery of Financial Statements.

(a) The Company shall deliver to (i) Ariad for so long as Ariad holds at least twenty percent (20%) of the shares of the Series A Preferred Stock (as adjusted for any stock splits, stock dividends, combinations, subdivisions, recapitalizations or the like with respect to such Series A Preferred Stock) originally issued to it and (ii) each other Investor (or transferee of such other Investor) that, together with its general partner and Affiliates (if any), holds at least 300,000 shares of Registrable Securities (appropriately adjusted for any stock split, dividend, combination or other recapitalization) (each, a “Major Investor”), provided that the Board has not determined in good faith that such Major Investor is an actual or potential competitor of the Company (provided further that Ariad shall not be deemed a competitor of the Company for purposes of Section 3.1(a)(i) or (ii)):

(i) as soon as practicable, but in any event within one hundred twenty (120) days after the end of each fiscal year of the Company, an unaudited income statement for such fiscal year, an unaudited balance sheet of the Company and statement of stockholders’ equity as of the end of such year, and an unaudited statement of cash flows for such year, such year-end financial reports to be in reasonable detail, prepared in accordance with generally accepted accounting principles (“GAAP”) (except that such financial statements may (A) be subject to normal year-end audit adjustments and (B) not contain all notes thereto that may be required in accordance with GAAP);

(ii) as soon as practicable, but in any event within forty-five (45) days after the end of each of the first three (3) quarters of each fiscal year of the Company, an unaudited income statement and statement of cash flows for such fiscal quarter and an unaudited balance sheet and a statement of stockholders’ equity as of the end of such fiscal quarter, all prepared in accordance with GAAP (except that such financial statements may (A) be subject to normal year-end audit adjustments and (B) not contain all notes thereto that may be required in accordance with GAAP);

(iii) not later than thirty (30) days prior to the start of each fiscal year, the Company’s annual operating and business plan, including, without limitation, consolidated capital and operating expense budgets, cash flow projections, and income and loss projections, for the Company in respect of such fiscal year, all itemized in reasonable detail; and

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(iv) such other information relating to the financial condition, business or corporate affairs of the Company as the Major Investor may from time to time reasonably request; provided, however, that the Company shall not be obligated under this subsection (iv) or any other subsection of Section 3.1 to provide information that (A) it deems in good faith to be a trade secret or similar confidential information or (B) the disclosure of which would adversely affect the attorney-client privilege between the Company and its counsel.

(b) Notwithstanding anything else in this Section 3.1 to the contrary, the Company may cease providing the information set forth in this Section 3.1 during the period starting with the date sixty (60) days before the Company’s good-faith estimate of the date of filing of a registration statement if it reasonably concludes it must do so to comply with the SEC rules applicable to such registration statement and related offering; provided that the Company’s covenants under this Section 3.1 shall be reinstated at such time as the Company is no longer actively employing its commercially reasonable efforts to cause such registration statement to become effective.

3.2 Inspection. The Company shall permit each Major Investor that is not an actual or potential competitor of the Company, as determined in good faith by the Board, at such Major Investor’s expense, to visit and inspect the Company’s properties, to examine its books of account and records and to discuss the Company’s affairs, finances and accounts with its officers, all at such reasonable times as may be requested by the Major Investor; provided, however, that the Company shall not be obligated pursuant to this Section 3.2 to provide access to any information that (A) it deems in good faith to be a trade secret or similar confidential information or (B) the disclosure of which would adversely affect the attorney-client privilege between the Company and its counsel or result in a conflict of interest.

3.3 Termination of Information and Inspection Covenants. The covenants set forth in Sections 3.1 and 3.2 shall terminate and be of no further force or effect upon the earlier to occur of (a) the consummation of the sale of securities pursuant to a registration statement under the Act in connection with the firm commitment underwritten offering of its securities to the general public or a Direct Listing, (b) when the Company first becomes subject to the periodic reporting requirements of Sections 12(g) or 15(d) of the 1934 Act, whichever event shall first occur and (c) the consummation of a Liquidation Event, as such term is defined in the Restated Certificate.

3.4 Right of First Offer. Subject to the terms and conditions specified in this Section 3.4 and applicable securities laws, the Company hereby grants to each Major Investor a right of first offer with respect to future sales by the Company of its Shares (as hereinafter defined). For purposes of this Section 3.4, the term “Major Investor” includes any Affiliates of a Major Investor. A Major Investor shall be entitled to apportion the right of first offer hereby granted it among itself and its partners and Affiliates in such proportions as it deems appropriate; provided that each such party and Affiliate agrees to enter into this Agreement and each of the Voting Agreement and Right of First Refusal and Co-Sale Agreement (as such terms are defined in the Series B Agreement), as an Investor under each such agreement.

Each time the Company proposes to offer any shares of, or securities convertible into or exchangeable or exercisable for any shares of, its capital stock (“Shares”), the Company shall first make an offering of such Shares to each Major Investor in accordance with the following provisions:

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(a) The Company shall deliver a notice in accordance with Section 4.5 (“Notice”) to the Major Investors stating (i) its bona fide intention to offer such Shares, (ii) the number of such Shares to be offered and (iii) the price and terms upon which it proposes to offer such Shares.

(b) By written notification received by the Company within twenty (20) calendar days after the giving of Notice, each Major Investor may elect to purchase, at the price and on the terms specified in the Notice, up to that portion of such Shares that equals the proportion that the number of shares of Registrable Securities issued and held by such Major Investor (assuming full conversion, exercise and/or exchange of all convertible, exercisable and/or exchangeable securities then outstanding) bears to the total number of shares of Common Stock of the Company then outstanding (assuming full conversion, exercise and/or exchange of all convertible, exercisable and/or exchangeable securities then outstanding). At the expiration of such twenty (20) calendar day period, the Company shall promptly, in writing, notify each Major Investor that elects to purchase all the shares available to it (a “Fully-Exercising Investor”) of any other Major Investor’s failure to do likewise. During the ten (10) calendar day period commencing after the Company has given such notice to the Fully-Exercising Investors, each Fully-Exercising Investor may elect to purchase that portion of the Shares for which Major Investors were entitled to subscribe, but which were not subscribed for by the Major Investors, that is equal to the proportion that the number of shares of Registrable Securities issued and held by such Fully-Exercising Investor bears to the total number of shares of Common Stock of the Company then outstanding (assuming full conversion, exercise and/or exchange of all convertible, exercisable and/or exchangeable securities then outstanding).

(c) If all Shares that Major Investors are entitled to obtain pursuant to Section 3.4(b) of this Agreement are not elected to be obtained as provided in Section 3.4(b) of this Agreement, the Company may, during the ninety (90) day period following the expiration of the period provided in Section 3.4(b) of this Agreement, offer the remaining unsubscribed portion of such Shares to any Person or Persons at a price not less than that, and upon terms no more favorable to the offeree than those, specified in the Notice. If the Company does not enter into an agreement for the sale of the Shares within such period, or if such agreement is not consummated within ninety (90) days of the execution thereof, the right provided hereunder shall be deemed to be revived and such Shares shall not be offered unless first reoffered to the Major Investors in accordance herewith.

(d) The right of first offer in this Section 3.4 shall not apply to securities that constitute “Excluded Securities” (as defined in the Restated Certificate) and in addition shall not be applicable to (i) the issuance and sale of Series B Preferred Stock pursuant to the Series B Agreement or (ii) the issuance of securities that are specifically deemed not to be subject to the right of first offer in this Section 3.4 by the written consent or affirmative vote of the Major Investors holding a majority of the Registrable Securities then held by all Major Investors. In addition to the foregoing, the right of first offer in this Section 3.4 shall not be applicable with respect to any Major Investor in any subsequent offering of Shares if (i) at the time of such offering, the Major Investor is not an “accredited investor,” as that term is then defined in Rule 501(a) of the Act and (ii) such offering of Shares is otherwise being offered only to accredited investors.

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(e) The rights provided in this Section 3.4 may not be assigned by any Major Investor except as provided in Section 3.4(a).

(f) The covenants set forth in this Section 3.4 shall terminate and be of no further force or effect upon the consummation of (i) the Initial Offering (other than a registration statement relating either to the sale of securities to employees of the Company pursuant to its stock option, stock purchase or similar plan or a SEC Rule 145 transaction) or a Direct Listing or (ii) a Liquidation Event, as such term is defined in the Restated Certificate.

3.5 Directors’ and Officers’ Insurance. The Company has as of the date hereof or shall within ninety (90) days of the date hereof use its commercially reasonable efforts to obtain from financially sound and reputable insurers directors and officers liability insurance in an amount and on terms and conditions satisfactory to the Board including a majority of the Preferred Directors (as defined in the Company’s current certificate of incorporation)(the “Preferred Directors”), and will use its commercially reasonable efforts to cause such insurance policy to be maintained until such time as the Board including a majority of the Preferred Directors determines that such insurance should be discontinued.

3.6 Observer Rights. As long as ARIAD Pharmaceuticals, Inc. (“Ariad”) holds at least fifty percent (50%) of the shares of Series A Preferred Stock (appropriately adjusted for any stock split, dividend, combination or other recapitalization) (or an equivalent amount of Common Stock issued upon conversion thereof) originally issued to Ariad pursuant to the Series A Stock Purchase Agreement, dated as of June 14, 2018 (as amended and restated from time to time), the Company shall invite a representative of Ariad to attend all meetings of its Board in a nonvoting observer capacity and, in this respect, shall give such representative copies of all notices, minutes, consents and other materials that it provides to its directors in connection therewith at the same time as provided to such directors or reasonably promptly thereafter; provided, however, that such representative shall agree to hold in confidence and trust all information so provided; and, provided further, that the Company reserves the right to withhold any information and to exclude such representative from any meeting or portion thereof if access to such information or attendance at such meeting could adversely affect the attorney-client privilege between the Company and its counsel or would result in disclosure of trade secrets to such representative or if such Investor or its representative is or is affiliated with an actual or potential competitor of the Company, as determined in good faith by the Board. Any observer shall be required to enter into a confidentiality agreement containing substantially similar terms as those set forth in Section 3.10 of this Agreement with the Company prior to the exercise of the rights contained in this Section 3.6.

3.7 Proprietary Information and Inventions Agreements. The Company shall require all employees and consultants with access to confidential information to execute and deliver a Proprietary Information and Inventions Agreement in substantially the form approved by the Board or a consulting agreement containing substantially similar proprietary rights assignment and confidentiality provisions.

3.8 Employee Agreements. Unless otherwise approved by the Board, all future employees of the Company who shall purchase, or receive options to purchase, shares of Common Stock following the date hereof shall be required to execute stock purchase or option

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agreements providing for (a) vesting of shares over a four (4) year period with the first twenty five percent (25%) of such shares vesting following twelve (12) months of continued employment or services, and the remaining shares vesting in equal monthly installments over the following thirty six (36) months thereafter and (b) a one hundred and eighty (180)-day lockup period in connection with the Initial Offering. The Company shall retain a right of first refusal on transfers until the Initial Offering and the right to repurchase unvested shares at cost.

3.9 Indemnification Matters. The Company hereby acknowledges that one (1) or more of the directors nominated to serve on the Board by the Investors (each a “Fund Director”) may have certain rights to indemnification, advancement of expenses and/or insurance provided by one or more of the Investors and certain of their affiliates (collectively, the “Fund Indemnitors”). The Company hereby agrees (a) that it is the indemnitor of first resort (i.e., its obligations to any such Fund Director are primary and any obligation of the Fund Indemnitors to advance expenses or to provide indemnification for the same expenses or liabilities incurred by such Fund Director are secondary), (b) that it shall be required to advance the full amount of expenses incurred by such Fund Director and shall be liable for the full amount of all expenses, judgments, penalties, fines and amounts paid in settlement by or on behalf of any such Fund Director to the extent legally permitted and as required by the Restated Certificate or Bylaws of the Company (or any agreement between the Company and such Fund Director), without regard to any rights such Fund Director may have against the Fund Indemnitors, and, (c) that it irrevocably waives, relinquishes and releases the Fund Indemnitors from any and all claims against the Fund Indemnitors for contribution, subrogation or any other recovery of any kind in respect thereof. The Company further agrees that no advancement or payment by the Fund Indemnitors on behalf of any such Fund Director with respect to any claim for which such Fund Director has sought indemnification from the Company shall affect the foregoing and the Fund Indemnitors shall have a right of contribution and/or be subrogated to the extent of such advancement or payment to all of the rights of recovery of such Fund Director against the Company.

3.10 Confidentiality. Each Investor agrees, severally and not jointly, that such Investor (a) will keep confidential, (b) will not disclose, divulge or use for any purpose (other than to monitor its investment in the Company) and (c) will protect to the same degree as it protects its own confidential information any confidential information obtained from the Company pursuant to the terms of this Agreement (including, without limitation, notice of the Company’s intention to file a registration statement), unless such confidential information (i) is known or becomes known to the public in general (other than as a result of a breach of this Subsection 3.10 by such Investor), (ii) is or has been independently developed or conceived by the Investor without use of the Company’s confidential information, or (iii) is or has been made known or disclosed to the Investor by a third party without a breach of any obligation of confidentiality such third party may have to the Company; provided, however, that an Investor may disclose confidential information (A) to its attorneys, accountants, consultants and other professionals to the extent necessary to obtain their services in connection with monitoring its investment in the Company, provided that such Persons are under a contractual or legal obligation to preserve the confidentiality of such information; (B) to any prospective purchaser that is not an actual or potential competitor of the Company (as determined in good faith by the Board) of any Registrable Securities from such Investor, if such prospective purchaser agrees to be bound by the provisions of this Subsection 3.10; (C) to any actual or prospective Affiliate,

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partner, member, stockholder or wholly owned subsidiary of such Investor in the ordinary course of business, provided that such Investor informs such Person that such information is confidential and directs such Person to maintain the confidentiality of such information; or (D) as may otherwise be required by law, provided that the Investor promptly notifies the Company of such legally required disclosure and takes reasonable steps to minimize the extent of any such required disclosure.

3.11 Waiver of Statutory Information Rights. Each Investor hereby acknowledges and agrees that until the consummation of the Initial Offering, such Investor shall hereby be deemed to have waived any rights such Investor might otherwise have had under Section 220 of the Delaware General Corporation Law (or under similar rights under other applicable law) to inspect for any proper purpose and to make copies and extracts from the Company’s stock ledger, a list of its stockholders and its other books and records or the books and records of any subsidiary. This waiver applies only in such Investor’s capacity as a stockholder and does not affect any other information and inspection rights such Investor may expressly have pursuant to Sections 3.1 and 3.2 of this Agreement. This Section 3.11 has been fully discussed by each of the Investors and these provisions will not be subject to any exceptions. Each Investor hereby further warrants and represents that such Investor has reviewed this waiver with its legal counsel, and that such Investor knowingly and voluntarily waives its rights otherwise provided by Section 220 of the Delaware General Corporation Law (or under similar rights under other applicable law).

3.12 Right to Conduct Activities. The Company hereby agrees and acknowledges that Foresite Capital Fund V, L.P. (together with its Affiliates) (“Foresite”) is a professional investment organization, and as such reviews the business plans and related proprietary information of many enterprises, some of which may compete directly or indirectly with the Company’s business (as currently conducted or as currently propose to be conducted). The Company hereby agrees that, to the extent permitted under applicable law, Foresite (and its Affiliates) shall not be liable to the Company for any claim arising out of, or based upon, (i) the investment by Foresite (or its Affiliates) in any entity competitive with the Company, or (ii) actions taken by any partner, officer, employee or other representative of Foresite (or its Affiliates) to assist any such competitive company, whether or not such action was taken as a member of the board of directors of such competitive company or otherwise, and whether or not such action has a detrimental effect on the Company; provided, however, that the foregoing shall not relieve (x) any of the Investors from liability associated with the unauthorized disclosure of the Company’s confidential information obtained pursuant to this Agreement, or (y) any director or officer of the Company from any liability associated with his or her fiduciary duties to the Company.

3.13 Board Matters. The Company shall reimburse the nonemployee directors for all reasonable out-of-pocket travel expenses incurred (consistent with the Company’s travel policy) in connection with attending meetings of the Board of Directors. Each non-employee director shall be entitled in such person’s discretion to be a member of all committees of the Board of Directors.

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3.14 CFIUS Filing Event. If and only if the Committee on Foreign Investment in the United States or any member agency thereof acting in its capacity as a member agency (“CFIUS”) requests or requires that the Company and an Investor to file a notice or declaration with CFIUS pursuant to the Defense Production Act of 1950, as amended, including all implementing regulations thereof (the “DPA”), with respect to an Investor’s investment in the Company (the “Covered Transaction”), or (ii) the Company or an Investor determine in good faith that a filing with CFIUS with respect to the Covered Transaction is advisable or required by applicable law, then in either case, (i) or (ii) (either to constitute a “CFIUS Filing Event”) the Company and such Investor shall, and shall cause any Affiliates to, cooperate and promptly make a CFIUS filing in the requested, required or advisable form in accordance with the DPA.

3.15 Termination of Certain Covenants. The covenants set forth in Sections 3.5, 3.6 and 3.7 shall terminate and be of no further force or effect upon the consummation of (a) the Initial Offering or a Direct Listing, or (b) a Liquidation Event, as that term is defined in the Restated Certificate.

4.1 Successors and Assigns. Except as otherwise provided herein, the terms and conditions of this Agreement shall inure to the benefit of and be binding upon the respective successors and assigns of the parties (including, without limitation, permitted transferees of any shares of Registrable Securities). Nothing in this Agreement, express or implied, is intended to confer upon any party other than the parties hereto or their respective successors and assigns any rights, remedies, obligations or liabilities under or by reason of this Agreement, except as expressly provided in this Agreement.

4.2 Governing Law. This Agreement shall be governed by and construed under the laws of the State of Delaware as applied to agreements among Delaware residents entered into and to be performed entirely within Delaware.

4.3 Counterparts. This Agreement may be executed by electronic signature and in two (2) or more counterparts, each of which shall be deemed an original, but all of which together shall constitute one (1) and the same instrument. Counterparts may be delivered by facsimile, electronic mail (including pdf or any electronic signature complying with the U.S. federal ESIGN Act of 2000, e.g., www.docusign.com) or other transmission method, and any counterpart so delivered shall be deemed to have been duly and validly delivered and be valid and effective for all purposes.

4.4 Titles and Subtitles. The titles and subtitles used in this Agreement are used for convenience only and are not to be considered in construing or interpreting this Agreement.

4.5 Notices. All notices and other communications given or made pursuant hereto shall be in writing and shall be deemed effectively given upon the earlier to occur of actual receipt or: (a) upon personal delivery to the party to be notified, (b) when sent by confirmed electronic mail or facsimile if sent during normal business hours of the recipient; if not, then on the next business day, (c) five (5) days after having been sent by registered or certified mail, return receipt requested, postage prepaid, or (d) one (1) day after deposit with a nationally recognized overnight courier, specifying next day delivery, with written verification of

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receipt. All notices and other communications shall be sent to the Company at the address set forth on the signature page attached hereto, to the attention of the President, with a copy to (which copy shall not constitute notice): Gunderson Dettmer Stough Villeneuve Franklin & Hachigian, LLP, 201 South Main Street, Suite 400, Ann Arbor, MI 48104, Attention: Marcia A. Hatch, ***@***, and to the other parties at the addresses set forth on their signature pages hereto (or at such other addresses as shall be specified by notice given in accordance with this Section 4.5).

4.6 Entire Agreement; Amendments. This Agreement (including the Exhibits hereto, if any) constitutes the full and entire understanding and agreement among the parties with regard to the subjects hereof and thereof. Any term of this Agreement (other than Section 3.1, Section 3.2, Section 3.3 and Section 3.4) may be amended and the observance of any term of this Agreement may be waived (either generally or in a particular instance and either retroactively or prospectively) only with the written consent of the Company and the Investors holding a majority of the Registrable Securities. The provisions of Section 3.1, Section 3.2, Section 3.3 and Section 3.4 may be amended or waived (either generally or in a particular instance and either retroactively or prospectively) only with the written consent of the Company and the Major Investors holding a majority of the Registrable Securities then held by all of the Major Investors (it being agreed that, in the event the provisions of Section 3.4 are waived with respect to a particular transaction without a Major Investor’s prior written consent and any Major Investor that participated in waiving such rights actually purchases Shares in such offering, then the Company shall grant to any non-waiving Major Investor the right to purchase the same percentage of its full pro rata share of Shares being offered as the highest percentage purchased by any Major Investor that participated in the waiving of such rights). Any amendment or waiver effected in accordance with this paragraph shall be binding upon each holder of any Registrable Securities, each future holder of all such Registrable Securities and the Company. The provisions of Section 3.6 may be amended or waived (either generally or in a particular instance and either retroactively or prospectively) only with the written consent of Ariad.

4.7 Severability. Whenever possible, each provision of this Agreement shall be interpreted in such manner as to be effective and valid under applicable law, but if any provision of this Agreement shall be held to be prohibited by or invalid under applicable law, such provision shall be ineffective only to the extent of such prohibition or invalidity, without invalidating the remainder of such provision or the remaining provisions of this Agreement.

4.8 Aggregation of Stock. All shares of Registrable Securities held or acquired by affiliated entities (including, without limitation, affiliated venture capital funds or venture capital funds under common investment management) or Persons shall be aggregated together for the purpose of determining the availability of any rights under this Agreement.

4.9 Additional Investors. Notwithstanding anything to the contrary contained herein, if the Company issues additional shares of the Company’s Series B Preferred Stock after the date hereof, any purchaser of such shares of Series B Preferred Stock may become a party to this Agreement by executing and delivering an additional counterpart signature page to this Agreement, and thereafter shall be deemed an “Investor” for all purposes hereunder. No action or consent by the Investors shall be required for such joinder to this Agreement by such additional Investor, so long as such additional Investor has agreed in writing to be bound by all of the obligations as an “Investor” hereunder.

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4.10 Dispute Resolution. The parties (a) hereby irrevocably and unconditionally submit to the jurisdiction of the state courts of Delaware and to the jurisdiction of the United States District Court for the District of Delaware for the purpose of any suit, action or other proceeding arising out of or based upon this Agreement, (b) agree not to commence any suit, action or other proceeding arising out of or based upon this Agreement except in the state courts of Delaware or the United States District Court for the District of Delaware, and (c) hereby waive, and agree not to assert, by way of motion, as a defense, or otherwise, in any such suit, action or proceeding, any claim that it is not subject personally to the jurisdiction of the foregoing courts, that its property is exempt or immune from attachment or execution, that the suit, action or proceeding is brought in an inconvenient forum, that the venue of the suit, action or proceeding is improper or that this Agreement or the subject matter hereof may not be enforced in or by such court.

WAIVER OF JURY TRIAL: EACH PARTY HEREBY WAIVES ITS RIGHTS TO A JURY TRIAL OF ANY CLAIM OR CAUSE OF ACTION BASED UPON OR ARISING OUT OF THIS AGREEMENT OR THE SUBJECT MATTER HEREOF. THE SCOPE OF THIS WAIVER IS INTENDED TO BE ALL-ENCOMPASSING OF ANY AND ALL DISPUTES THAT MAY BE FILED IN ANY COURT AND THAT RELATE TO THE SUBJECT MATTER OF THIS AGREEMENT, INCLUDING, WITHOUT LIMITATION, CONTRACT CLAIMS, TORT CLAIMS (INCLUDING NEGLIGENCE), BREACH OF DUTY CLAIMS, AND ALL OTHER COMMON LAW AND STATUTORY CLAIMS. THIS SECTION HAS BEEN FULLY DISCUSSED BY EACH OF THE PARTIES HERETO AND THESE PROVISIONS WILL NOT BE SUBJECT TO ANY EXCEPTIONS. EACH PARTY HERETO HEREBY FURTHER WARRANTS AND REPRESENTS THAT SUCH PARTY HAS REVIEWED THIS WAIVER WITH ITS LEGAL COUNSEL, AND THAT SUCH PARTY KNOWINGLY AND VOLUNTARILY WAIVES ITS JURY TRIAL RIGHTS FOLLOWING CONSULTATION WITH LEGAL COUNSEL.

4.11 Effect on Prior Agreement. Upon the effectiveness of this Agreement, the Prior Agreement shall be amended and restated in its entirety by this Agreement and shall be of no further force or effect.

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IN WITNESS WHEREOF, the parties have executed this Agreement as of the date first above written.

SIGNATURE PAGE TO AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT

FOR THESEUS PHARMACEUTICALS, INC.

IN WITNESS WHEREOF, the parties have executed this Agreement as of the date first above written.

SIGNATURE PAGE TO AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT

FOR THESEUS PHARMACEUTICALS, INC.

IN WITNESS WHEREOF, the parties have executed this Agreement as of the date first above written.

SIGNATURE PAGE TO AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT

FOR THESEUS PHARMACEUTICALS, INC.

IN WITNESS WHEREOF, the parties have executed this Agreement as of the date first above written.

SIGNATURE PAGE TO AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT

FOR THESEUS PHARMACEUTICALS, INC.

IN WITNESS WHEREOF, the parties have executed this Agreement as of the date first above written.

SIGNATURE PAGE TO AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT

FOR THESEUS PHARMACEUTICALS, INC.

IN WITNESS WHEREOF, the parties have executed this Agreement as of the date first above written.

SIGNATURE PAGE TO AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT

FOR THESEUS PHARMACEUTICALS, INC.

IN WITNESS WHEREOF, the parties have executed this Agreement as of the date first above written.

SIGNATURE PAGE TO AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT

FOR THESEUS PHARMACEUTICALS, INC.

IN WITNESS WHEREOF, the parties have executed this Agreement as of the date first above written.

SIGNATURE PAGE TO AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT

FOR THESEUS PHARMACEUTICALS, INC.

IN WITNESS WHEREOF, the parties have executed this Agreement as of the date first above written.

SIGNATURE PAGE TO AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT

FOR THESEUS PHARMACEUTICALS, INC.

IN WITNESS WHEREOF, the parties have executed this Agreement as of the date first above written.

SIGNATURE PAGE TO AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT

FOR THESEUS PHARMACEUTICALS, INC.

IN WITNESS WHEREOF, the parties have executed this Agreement as of the date first above written.

SIGNATURE PAGE TO AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT

FOR THESEUS PHARMACEUTICALS, INC.

IN WITNESS WHEREOF, the parties have executed this Agreement as of the date first above written.

SIGNATURE PAGE TO AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT

FOR THESEUS PHARMACEUTICALS, INC.

IN WITNESS WHEREOF, the parties have executed this Agreement as of the date first above written.

SIGNATURE PAGE TO AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT

FOR THESEUS PHARMACEUTICALS, INC.

IN WITNESS WHEREOF, the parties have executed this Agreement as of the date first above written.

SIGNATURE PAGE TO AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT

FOR THESEUS PHARMACEUTICALS, INC.

SCHEDULE A

SCHEDULE OF INVESTORS

S-1

S-2

S-3

S-4