Document:

EX-10.4

 Exhibit 10.4 

CYTEIR THERAPEUTICS, INC. 

RESTRICTED STOCK AGREEMENT 

This Restricted Stock Agreement (the “Agreement”) is entered into as of the effective date set forth on the signature page
hereto (the “Effective Date”) by and between Cyteir Therapeutics, Inc., a Delaware corporation (the “Company”), and the person executing a counterpart signature page hereto (referred to herein as
“Founder”). 
 WHEREAS, the Founder desires to purchase, and the Company has agreed to issue, shares of the
Company’s capital stock on the terms set forth herein; 
 WHEREAS, the Company and the Founder have agreed to place certain
restrictions on the shares of the Company’s capital stock issued by the Company to the Founder; and 
 WHEREAS, the parties
hereto are willing to execute this Agreement and to be bound by the provisions hereof. 
 NOW, THEREFORE, in consideration of the
mutual covenants herein contained and other valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the Founder and the Company hereby agree as follows: 

1.    Sale and Issuance of Shares. 

(a)    Subject to the terms and conditions of this Agreement, the Founder does hereby subscribe for and agree to purchase,
and the Company agrees to sell to the Founder, at the Closing (defined below), the aggregate number of shares of the common stock of the Company, par value $0.001 per share (“Common Stock”), set forth on the signature page hereto,
as adjusted to reflect any stock dividend, stock split or other form of recapitalization occurring after the Effective Date (such shares are referred to herein as the “Restricted Stock”). The Founder acknowledges and agrees that the
shares of Restricted Stock issued and sold hereunder are in exchange for and in cancellation of any and all previous options or other equity promised or offered at any time to the Founder (if any), all which are hereby acknowledged to be unissued,
unexercised, void and cancelled, without any further force or effect. 
 (b)    In consideration of and as payment for
the issuance of the shares of Restricted Stock to be purchased hereunder, the Founder shall deliver to the Company at the Closing the aggregate purchase price specified on the signature page hereto, based upon the purchase price per share specified
thereon (the “Purchase Price”). 
 (c)    The obligations of the Company hereunder are subject to the
fulfillment, on or before the Closing, of each of the following conditions: 
 (i)    The Founder shall have delivered
payment in full of the aggregate purchase price for the shares of Restricted Stock specified on the signature page hereto together with a stock power in favor of the Company in the form of Exhibit A hereto; 

 (ii)    The Founder shall have executed and delivered a Non-Disclosure and Inventions Assignment Agreement in substantially the form of Exhibit B hereto (the “Non-Disclosure and Inventions Assignment
Agreement”); 
 (iii)    All authorizations, approvals or permits, if any, of any governmental authority or
regulatory body of the United States or of any state that may be required in connection with the lawful issuance and sale of the Restricted Stock pursuant to this Agreement shall have been duly obtained and shall be effective at the Closing, other
than filings which are required to be made after the Closing and which will be duly made on a timely basis. 

(d)    The closing of the purchase and sale of the Restricted Stock being purchased by the Founder under this Agreement
(the “Closing”) shall occur at the offices of Choate, Hall & Stewart, LLP, Two International Place, Boston, MA at 10:00 AM on the Effective Date or at such other time and place as may be mutually agreed by the Company and
the Founder. 
 2.    General Restrictions. 

(a)    Investment Representations. The Founder represents, warrants and acknowledges that the Founder:
(i) has had an opportunity to ask questions of and receive answers from a Company representative concerning the terms and conditions of this investment; (ii) is acquiring the Restricted Stock with the Founder’s own funds, for the
Founder’s own account for the purpose of investment, and not with a view to any resale or other distribution thereof in violation of the Securities Act of 1933, as amended (the “Securities Act”); (iii) is a sophisticated
investor with such knowledge and experience in financial and business matters as to be able to evaluate the merits and risks of an investment in the Restricted Stock; and (iv) is able to and must bear the economic risk of the investment in the
Restricted Stock for an indefinite period of time because the Restricted Stock has not been registered under the Securities Act, and therefore, cannot be offered or sold unless the Restricted Stock is subsequently registered under the Securities Act
or an exemption from such registration is available. The Founder acknowledges and understands that the Restricted Stock has not been registered under the Securities Act, nor registered pursuant to the provisions of the securities laws or other laws
of any other applicable jurisdictions, in reliance on exemptions for private offerings contained in Section 4(2) of the Securities Act and in the laws of such jurisdictions. 

(b)    Securities Law Restrictions. Regardless of whether the offering and sale of shares of the
Company’s Common Stock have been registered under the Securities Act or have been registered or qualified under the securities laws of any state, the Company at its discretion may impose restrictions (including the placement of appropriate
legends on stock certificates or the imposition of stop-transfer instructions) upon the transfer of such shares (including the Restricted Stock) if, in the judgment of the Company, such restrictions are
necessary or desirable in order to achieve compliance with the Securities Act, the securities laws of any state or any other law. 

  
 2 

 (c)    Legends. The Founder acknowledges that all
certificates evidencing shares of Restricted Stock shall bear a legend in substantially the following form, in addition to all other legends required by law or any other agreements to which the Founder is a party: 

“THE SHARES REPRESENTED HEREBY MAY NOT BE SOLD, ASSIGNED, TRANSFERRED, ENCUMBERED OR IN ANY MANNER DISPOSED OF, EXCEPT IN COMPLIANCE WITH
THE TERMS OF A RESTRICTED STOCK AGREEMENT PURSUANT TO WHICH SUCH SHARES WERE ACQUIRED. SUCH AGREEMENT PROVIDES THAT SUCH SHARES ARE SUBJECT TO AN OPTION TO PURCHASE AND OTHER RESTRICTIONS. THE SECRETARY OF THE COMPANY WILL UPON WRITTEN REQUEST
FURNISH A COPY OF SUCH AGREEMENT TO THE HOLDER HEREOF WITHOUT CHARGE.” 
 The Founder further acknowledges that all certificates evidencing shares of
Restricted Stock subject to this Agreement shall bear the following additional legend (and such other restrictive legends as are required or deemed advisable under the provisions of any applicable law): 

“THE SHARES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT BE SOLD, PLEDGED, OR
OTHERWISE TRANSFERRED WITHOUT AN EFFECTIVE REGISTRATION THEREOF UNDER SUCH ACT OR AN OPINION OF COUNSEL, SATISFACTORY TO THE COMPANY AND ITS COUNSEL, THAT SUCH REGISTRATION IS NOT REQUIRED.” 

(d)    Administration. The Founder acknowledges that the Company shall make a notation regarding the
restrictions on transfer of the Restricted Stock in its stock books, and the Restricted Stock shall be transferred on the books of the Company only if transferred or sold pursuant to an effective registration statement under the Securities Act and
applicable state securities laws covering such Restricted Stock or pursuant to and in compliance with the provisions of Section 4 or 5 hereof. A copy of this Agreement, together with any amendments thereto, shall remain on file with the
Secretary of the Company and shall be available for inspection to any properly interested person without charge within five (5) days after the Company’s receipt of a written request therefor. 

(e)    Binding Agreement. The Founder represents and warrants that this Agreement constitutes a valid and
legally binding obligation on the Founder, enforceable against the Founder in accordance with its terms. The Founder further represents that such Founder is not a party to any other agreement that would prevent Founder from performing Founder’s
obligations hereunder. 
 3.    Vesting of Restricted Stock. 

(a)    Vesting Schedule. The Founder’s ownership of the Restricted Stock shall vest as a result of the
Founder’s performance of services to the Company as an employee, director, officer and/or consultant (“Business Relationship”) in accordance with the vesting schedule set forth in Section A of the Vesting Schedule on the
signature page hereto (the “Basic Vesting Schedule”). Such shares of Restricted Stock as have not vested at any given time are referred to herein as “Unvested Restricted Stock” and shares of Restricted Stock which
have vested at any given time are referred to herein as “Vested Restricted Stock”. 

  
 3 

 (b)    For purposes hereof, the Founder’s Business Relationship
with the Company shall not be considered as having terminated during any leave of absence if such leave of absence has been approved in writing by the Company and if such written approval contractually obligates the Company to continue the
Founder’s Business Relationship with the Company after the approved period of absence; in the event of such an approved leave of absence, vesting of Unvested Restricted Stock shall be suspended (and the period of the leave of absence shall be
added to all vesting dates) unless otherwise provided in the Company’s written approval of the leave of absence. This Agreement shall not be affected by any change of Business Relationship within or among the Company and any Related Company
(defined below) so long as the Founder continuously remains an employee, consultant, officer or director of the Company or any Related Company. 

(c)    Acceleration of Vesting. 

(i)    Upon the consummation of a Change of Control (as defined below) that occurs at any time during the period of the
Founder’s Business Relationship with the Company or any parent corporation or any subsidiary thereof (each, a “Related Company” and collectively with the Company, the “Related Companies”), the Basic Vesting
Schedule shall accelerate as set forth in Section B set forth on the signature page hereto (the “Accelerated Vesting Schedule”). 

(ii)    For purposes of this Agreement, “Change of Control” shall mean (A) the Company merges with
or into or consolidates with any other corporation or sells, leases or otherwise disposes of all or substantially all of its assets or properties, unless the stockholders of the Company, before giving effect to such merger, consolidation or sale,
lease or other disposition of assets, beneficially own at least fifty percent (50%) of the outstanding shares of capital stock of, or other equity interests in, the surviving or acquiring corporation or entity (calculated on a fully diluted basis);
or (B) any person (other than persons who were stockholders of the Company prior to such transaction or any venture capital investor making a portfolio investment), together with its affiliates or associates (as defined in Rule 12b-2 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”) or any successor rule thereto), acquires beneficial ownership (as defined in Rule
13d-3 under the Exchange Act) of fifty percent (50%) or more of the outstanding shares of the Company’s Common Stock. 

4.    Right of Repurchase. 

(a)    Scope of Right of Repurchase. The shares of Unvested Restricted Stock shall be subject to a right (but
not an obligation) of repurchase by the Company as set forth in this Section 4 (the “Right of Repurchase”). The Founder shall not transfer any shares of Unvested Restricted Stock, or any interest in any Unvested Restricted
Stock, except for a Permitted Transfer (as defined in Section 5(b) below). 
 (b)    Condition Precedent to
Exercise. The Right of Repurchase shall be exercisable with respect to any shares of Unvested Restricted Stock only during the 45-day period following the date on which the Founder’s Business
Relationship with any Related Company terminates for any reason. 

  
 4 

 (c)    Price. If the Company exercises the Right of
Repurchase, it shall pay to the Founder and/or any Permitted Transferee thereof (as defined in Section 5(b) below) holding Unvested Restricted Stock, as applicable, with respect to each share of Unvested Restricted Stock, the Purchase Price
thereof (as defined in Section 1(b)), as adjusted to reflect any stock dividend, stock split or other form of recapitalization occurring after the Effective Date (such amount being hereinafter referred to as the “Repurchase
Price”). 
 (d)    Exercise of Right of Repurchase. The Right of Repurchase shall be exercised by
the Company, which exercise must be authorized by the affirmative vote of at least a majority of the members of the Company’s Board of Directors entitled to vote thereon (other than the Founder if the Founder is then a member of the Board of
Directors), by delivering to the Founder or his executor (and, if applicable, to any Permitted Transferee thereof holding shares of Unvested Restricted Stock) written notice (the “Repurchase Notice”) specifying the number of shares
of Unvested Restricted Stock to be purchased and the Repurchase Price applicable thereto, and payment of the aggregate Repurchase Price prior to the expiration of the 45-day period specified in subsection
(b) above. At the Company’s option, payment of the aggregate Repurchase Price may be made (i) by delivery to the Founder or his executor (and, if applicable, to any such Permitted Transferee), with the Repurchase Notice, of a check
payable to the order of the Founder or his executor (and, if applicable, to any such Permitted Transferee) in the amount of the Repurchase Price for the number of shares of Unvested Restricted Stock being purchased, or (ii) in the event the
Founder is indebted to the Company, by cancellation by the Company of an amount of such indebtedness equal to the Repurchase Price for the number of shares of Unvested Restricted Stock being purchased, or (iii) by a combination of (i) and
(ii) so that the combined payment and cancellation of indebtedness equals such aggregate Repurchase Price. Upon delivery of the Repurchase Notice and payment of the aggregate Repurchase Price in any of the ways described above, the Company shall
become the legal and beneficial owner of the shares of Unvested Restricted Stock being purchased and all rights and interest therein or related thereto, and the Company shall have the right to transfer to its own name the number of shares of
Unvested Restricted Stock being purchased by the Company, without further action by the Founder. If and to the extent the Right of Repurchase is not so exercised by delivering the Repurchase Notice and payment of the aggregate Repurchase Price
within the 45-day period specified in subsection (b) above, the Right of Repurchase shall automatically expire and terminate effective upon the expiration of such
45-day period and the terminated Founder (and any such Permitted Transferee) shall continue to hold such shares of Restricted Stock pursuant to all of the other provisions of this Agreement. 

(e)    Free Assignment. Notwithstanding anything set forth in this Section 4 to the contrary, prior to
the exercise by the Company of its Right of Repurchase, one or more persons or entities may be designated by the Company who shall have the right, but not the obligation, to exercise the Right of Repurchase and to acquire, in lieu of the Company,
some or all (as determined by the Company) of the shares of Unvested Restricted Stock that the Company is entitled to purchase from the Founder and any Permitted Transferee hereunder by following the procedures set forth in subsection
(d) above. 

  
 5 

 (f)    Escrow. Upon issuance, the certificates
representing Restricted Stock shall be deposited in escrow with the Company to be held and administered by the Company in accordance with the provisions of this Agreement and the Founder shall execute and deliver a stock power in favor of the
Company in substantially the form attached as Exhibit A. In addition, any new, substituted or additional securities or other property distributed upon or in respect of shares of Restricted Stock which are subject to the Right of
Repurchase shall immediately be delivered to the Company to be held in escrow. Subject to the provisions hereof, the Founder or any Permitted Transferee, as the case may be, shall have all rights of a stockholder with respect to Restricted Stock
held in escrow, including without limitation the right to vote such shares of Restricted Stock and the right to receive any cash dividends thereon All regular cash dividends on such shares (or other securities at the time held in escrow) shall be
paid directly to the Founder and/or any Permitted Transferee thereof, as applicable, and shall not be held in escrow. Restricted Stock, together with any other assets or securities held in escrow hereunder, shall be (i) surrendered to the
Company for repurchase and cancellation upon the Company’s exercise of its Right of Repurchase, or (ii) released to the Founder and/or such Permitted Transferee upon the Founder’s or such Permitted Transferee’s request to the
extent the shares are no longer subject to a Right of Repurchase (but not more frequently than once every six months). In any event, when all of the shares of Restricted Stock (and any other vested assets and securities attributable thereto) are no
longer subject to a Right of Repurchase, such shares shall be released to the Founder and/or such Permitted Transferee. 

5.    Stock Transfer Restrictions. 

(a)    Restriction on Transfer. The Founder acknowledges that the Restricted Stock is subject to transfer
restrictions. Except as otherwise provided in subsection (b) below, the Founder shall not, while the Restricted Stock is subject to the Right of Repurchase, sell, assign, transfer, pledge, hypothecate or otherwise dispose of, by operation of
law or otherwise, (collectively, “Transfer”) any of the shares of Restricted Stock, or any interest therein, unless and until such shares of Restricted Stock are no longer subject to the Right of Repurchase. 

(b)    Permitted Transfers. Notwithstanding the foregoing, the Founder may transfer any or all of his shares
of Restricted Stock to a Permitted Transferee in a Permitted Transfer. As used herein, a “Permitted Transfer” shall mean a transfer of shares of Restricted Stock by the Founder (i) by beneficiary designation, will or intestate
succession, or (ii) to any member of the Founder’s family (which for purposes of this definition shall include a spouse, child (natural or adopted) or any other lineal descendant of the Founder or his/her spouse) or to the trustee of any
trust, partnership or limited liability company established by the Founder for the benefit of, or the ownership interests of which are wholly-owned by, the Founder or any such members of the Founder’s
family, provided that in either case such transferee (each, a “Permitted Transferee”) agrees in writing on a form prescribed by the Company to be bound by all provisions of this Agreement. 

6.    Tax Consequences. 

(a)    The Founder has reviewed with his own tax advisors the federal, state, local and foreign tax consequences of this
stock purchase and the transactions contemplated by this Agreement (including any tax consequences that may result under recently enacted tax legislation). The Founder is relying solely on such advisors and not on any statements or representations
of the Company or any of its agents. The Founder understands that the Founder (and not the Company) shall be responsible for the Founder’s own tax liability that may arise as a result of this stock purchase or the transactions contemplated by
this Agreement. The Founder understands that Section 83 of the Internal Revenue Code, as amended (the “Code”), taxes as ordinary income the difference between the amount paid for the Restricted Stock and the fair market value
of the Restricted Stock as of the date any restrictions on the Restricted Stock lapse. In this context, “restriction” includes the right of the Company to buy back the Restricted Stock pursuant to certain of its rights under Section 4
of this Agreement. 

  
 6 

 (b)    The Founder hereby agrees to deliver to the Company a signed copy
of any instrument, letter or other document that the Founder may execute and file with the Internal Revenue Service evidencing his election under Section 83(b) of the Code to treat his receipt of Restricted Stock as included in his gross income
in the year of receipt. The Founder shall deliver the said copy of any such instrument of election to the Company within five (5) days after the date on which any such election is required to be made in accordance with the appropriate
provisions of the Code or applicable Regulations thereunder. 
 THE FOUNDER ACKNOWLEDGES THAT IT IS FOUNDER’S SOLE RESPONSIBILITY, AND
NOT THE COMPANY’S, TO FILE TIMELY AN ELECTION UNDER SECTION 83(B), EVEN IF THE FOUNDER REQUESTS THE COMPANY OR ITS REPRESENTATIVES TO MAKE THIS FILING ON THE FOUNDER’S BEHALF. 

(c)    It is understood by the parties hereto that as a result of the issuance of the Restricted Stock and the execution
of this Agreement, the Company may be obligated to pay withholding taxes in respect of the Restricted Stock at the time the Founder becomes subject to Federal income taxation with respect to the Restricted Stock and the Company has the right to
deduct from payments of any kind otherwise due to the Founder any federal, state or local taxes of any kind required by law to be withheld with respect to the purchase of the Restricted Stock by the Founder. In the event that at the time such
withholding tax obligations arise (i) the Founder is no longer in the employ of the Company, or (ii) the Founder’s other cash compensation from the Company is not sufficient to meet such withholding tax obligations, the Founder hereby
agrees to reimburse the Company for all withholding taxes required to be paid in respect of this transaction within thirty (30) days after written request therefor is made to the Founder. Such request shall be made at or about the time the
Company is required to pay such withholding taxes. In the event the Company determines that it is not obligated to withhold taxes payable by the Founder with respect to the Restricted Stock, but that it is later held liable due to any non-payment of taxes on the part of the Founder, the Founder agrees on his behalf, and on behalf of his heirs, executors, administrators, legal representatives and assigns, to indemnify the Company in the amount of
any payment made by it in respect of such liability. 
 7.    No Retention Rights; Non-Solicitation Covenant. 
 (a)    No Retention Rights. Nothing in
this Agreement shall confer upon the Founder any right to a continued Business Relationship for any period of specific duration or interfere with or otherwise restrict in any way the rights of any Related Company or of the Founder, which rights are
hereby expressly reserved by each, to terminate his or her Business Relationship at any time and for any reason, with or without cause. 

  
 7 

(b)    Non-Solicitation. In consideration of the
Company’s issuance of the Restricted Stock to the Founder in accordance with the provisions hereof, and in further consideration of and as a condition precedent to the Founder’s Business Relationship with the Related Companies, the Founder
agrees that, during the period of the Founder’s Business Relationship with the Related Companies, and for a period of twelve (12) months after any termination or cessation of the Founder’s Business Relationship with the Related
Companies, whether with or without cause, the Founder will not in any capacity, either separately, jointly or in association with others, directly or indirectly, solicit any of the employees, customers, suppliers, consultants or advisors of the
Related Companies that were such with respect to the Related Companies at any time during the twelve (12) months immediately preceding the date of the termination or cessation of the Founder’s Business Relationship or who becomes such with
respect to the Related Companies at any time during the twelve (12) months immediately following the date of the termination or cessation of the Founder’s Business Relationship, to terminate or otherwise modify their relationship with the
Related Companies. 
 (c)    The Founder’s obligations under this Agreement, including without limitation under
this Section 7, shall survive the termination or cessation of Founder’s Business Relationship with the Related Companies. 

(d)    The Founder acknowledges that the restrictions imposed by this Agreement are necessary for the protection of the
business, goodwill and other legitimate interests of the Related Companies and are considered by the Founder to be reasonable for such purposes. 

(e)    FOUNDER UNDERSTANDS THAT THIS AGREEMENT MAY RESTRICT HIS OR HER RIGHT TO ACCEPT EMPLOYMENT OR PERFORM SERVICES
ON BEHALF OF OTHER COMPANIES DURING AND AFTER THE PERIOD OF HIS OR HER BUSINESS RELATIONSHIP WITH THE COMPANY. FOUNDER HAS READ ALL OF THE PROVISIONS OF THIS AGREEMENT AND FOUNDER UNDERSTANDS, AND AGREES TO, EACH OF SUCH PROVISIONS. 

8.    Miscellaneous Provisions. 

(a)    Notice. Any notice required by the terms of this Agreement shall be given in writing and shall be
deemed effective upon (i) personal delivery; (ii) when sent by confirmed electronic mail or facsimile if sent during normal business hours of the recipient, and if not so confirmed, then on the next business day; (iii) one (1) day
after deposit with a nationally recognized overnight courier, specifying next day delivery, with written verification of receipt; or (iv) five (5) days after deposit with the United States Postal Service, by registered or certified mail, return
receipt requested, with postage and fees prepaid. Notice shall be addressed to the Company at its principal executive office and to the Founder at the address that he or she most recently provided to the Company in writing. 

  
 8 

 (b)    Entire Agreement. This Agreement, together with the
Non-Disclosure and Inventions Assignment Agreement entered into as of the date hereof (as the same may be amended or restated from time to time), constitutes the entire understanding between the parties hereto
with regard to the subject matter hereof, and supersedes any other agreements, representations or understandings (whether oral or written and whether express or implied) which relate to the subject matter hereof. 

(c)    Successors and Assigns. The Company shall have the right to assign this Agreement to its
subsidiaries, affiliates, successors and designated assigns, and all covenants and agreements hereunder shall inure to the benefit of and be enforceable by said subsidiaries, affiliates, successors or designated assigns. Founder may not assign this
Agreement, or any rights or obligations hereunder, absent the prior written consent of the Company. Furthermore, Founder expressly consents to be bound by the provisions of this Agreement for the benefit of the Related Companies or affiliates of the
Related Companies in the event the Company desires to assign and transfer Founder’s Business Relationship to such Related Company or affiliate without the necessity that this Agreement be amended in writing or resigned at the time of such
assignment or transfer. 
 (d)    Adjustment for Stock Splits, Stock Dividends, etc. 

(i)    If from time to time during the term of the Right of Repurchase there is any stock
split-up, stock dividend, stock distribution or other reclassification of the Common Stock of the Company, any and all new, substituted or additional securities to which the Founder is entitled by reason of
his ownership of Restricted Stock shall be automatically subject to the Right of Repurchase, the restrictions on transfer and the other provisions of this Agreement in the same manner and to the same extent as the shares of Restricted Stock, and the
Repurchase Price, number of shares of Restricted Stock, and vesting schedule shall be appropriately adjusted. 

(ii)    If the shares of Restricted Stock are converted into or exchanged for, or stockholders of the Company receive by
reason of any distribution in total or partial liquidation, securities of another corporation or other property (including cash), or pursuant to any merger or consolidation of the Company or acquisition of its assets, then the rights of the Company
under this Agreement shall apply to the securities or other property received upon such conversion, exchange, distribution, merger or consolidation in the same manner and to the same extent as the Restricted Stock. 

(e)    Choice of Law. This Agreement shall be governed by, and construed and enforced in accordance with,
the laws of the State of Delaware. 
 (f)    Termination of Rights as Stockholder. If the Company makes
available, at the time and place and in the amount and form provided in this Agreement, the consideration for the shares of Restricted Stock to be purchased in accordance with Section 4, then after such time the person from whom such shares are
to be purchased shall no longer have any rights as a holder of such shares (other than the right to receive payment of such consideration in accordance with this Agreement). Such shares of Restricted Stock shall be deemed to have been purchased in
accordance with Section 4, whether or not the certificate(s) therefor have been delivered as required by this Agreement. 

  
 9 

 (g)    Remedies. The Founder agrees that the Company will
be irreparably damaged if this Agreement is not specifically enforced. Upon a breach or threatened breach of the terms, covenants or conditions of this Agreement by the Founder, the Company shall, in addition to all other remedies available, be
entitled to a temporary or permanent injunction against the Founder, without showing any actual damage, and/or a decree for specific enforcement in accordance with the provisions hereof. 

(h)    Severability. Founder hereby agrees that each provision herein shall be treated as a separate and
independent clause, and the unenforceability of any one clause shall in no way impair the enforceability of any of the other clauses herein. In case any provisions (or portions thereof) contained in this Agreement shall, for any reason, be held
invalid, illegal or unenforceable in any respect, Founder agrees that such invalidity, illegality or unenforceability shall not affect the other provisions of this Agreement, and this Agreement shall be construed as if such invalid, illegal or
unenforceable provision had never been contained herein. If, moreover, any one or more of the provisions contained in this Agreement shall for any reason be held to be excessively broad as to duration, geographical scope, activity or subject so as
to be unenforceable at law, Founder agrees that such provision or provisions shall be construed by the appropriate judicial body by limiting and reducing it or them, so as to be enforceable to the extent compatible with the applicable law as it
shall then appear. 
 (i)    Amendments; Waivers. This Agreement may only be amended or modified in
writing signed by the Founder and the Company. No party shall be deemed to waive any rights hereunder unless such waiver is in writing and signed by such party. A waiver in writing on or more occasions shall not be deemed to be a waiver for any
future occasions. 
 (j)    Counterparts. This Agreement may be executed in counterparts, including
counterparts by telecopier, each of which shall be deemed an original, but all of which when taken together shall constitute one and the same instrument. 

(k)    Captions. Captions are for convenience only and are not deemed to be part of this Agreement. 

(l)    Pronouns. Whenever the context may require, any pronouns used in this Agreement shall include the
corresponding masculine, feminine or neuter forms, and the singular forms of nouns and pronouns shall include the plural and vice versa. 

[The next page is the signature page.] 

  
 10 

 CYTEIR THERAPEUTICS, INC. 

RESTRICTED STOCK AGREEMENT 

Counterpart Signature Page 

IN WITNESS WHEREOF, this Agreement has been executed as of the effective date set forth below on the next succeeding Counterpart Signature
Page. 
  

			
	CYTEIR THERAPEUTICS, INC.
		
	By:	 	
                     
                                         
              

	Name:	 	
	Title:	 	

  
 Cyteir Restricted Stock
Agreement 

 CYTEIR THERAPEUTICS, INC. 

RESTRICTED STOCK AGREEMENT 

Counterpart Signature Page Cont’d 

FOUNDER 
  

	
	  

	Name:
	
	Address:

  
 Effective Date: [●] 

Shares of Common Stock: [●] 
 Per Share Consideration Paid
for Common Stock: $[●] 
 Aggregate Purchase Price: $[●] 

VESTING SCHEDULE 

A.    Basic Vesting: 
  

	 	•	 	 50% of the shares of Restricted Stock will become Vested Restricted Stock on the Effective Date; and

  

	 	•	 	 An additional 25% of the Restricted Stock will become Vested Restricted Stock upon the initial closing of a
Series A Preferred Stock financing of the Company and the determination by a majority of the Board of Directors (exclusive of the Founder, if he is then serving on the Board of Directors) that the Founder played a fundamental role in achieving the
Series A Preferred Stock financing; and 

  

	 	•	 	 The remaining 25% of the Restricted Stock will become Vested Restricted Stock ratably over a period of time to be
determined by the Board of Directors (but not to exceed three (3) years) if, following completion of the Series A Preferred Stock financing, Founder is appointed or elected, or continues, to serve as a member of the Board of Directors. If
Founder does not so join the Board of Directors within three (3) months following the initial closing of the Series A Preferred Stock Financing, any shares of Unvested Restricted Stock under this subparagraph will be subject to the Right of
Repurchase in Section 4. 

 B.    Accelerated Vesting: 

Upon the consummation of a Change of Control, 100% of any shares that are then Unvested Restricted Stock shall become Vested Restricted Stock. 

 EXHIBIT A 

to Restricted Stock Agreement 

ASSIGNMENT SEPARATE FROM CERTIFICATE 

FOR VALUE RECEIVED, I, [●], hereby sell, assign and transfer unto Cyteir Therapeutics, Inc., a Delaware corporation (the
“Company”),
                    (                    )
shares of the common stock of the Company standing in my name on the books of said corporation represented by Certificate No.          herewith and do hereby irrevocably constitute and appoint the
Company’s transfer agent, Choate, Hall & Stewart, LLP, attorney-in-fact to transfer the said stock on the books of the within named corporation with full
power of substitution in the premises. 
 This Stock Assignment may be used only in accordance with the Restricted Stock Agreement between
Cyteir Therapeutics, Inc. and the undersigned. 
  

							
	
Dated:                    

	 		 	Signature:	 	
                     
                    

				
		 		 	Name:	 	
                     
                    

  
 2EX-10.5

 Exhibit 10.5 

CYTEIR THERAPEUTICS, INC. 

INCENTIVE STOCK OPTION AGREEMENT 

Cyteir Therapeutics, Inc. (the “Company”) hereby grants the following stock option pursuant to its 2012 Stock Incentive Plan,
as amended (the “Plan”). The terms and conditions attached hereto are also a part hereof. 
  

			
	 Name of optionee (the “Optionee”):
	  	As Per Carta
		
	 Social Security number of Optionee:
	  	
		
	 Date of this option grant:
	  	As Per Carta
		
	 Option Expiration Date:
	  	As Per Carta
		
	 Number of shares of the Company’s Common Stock subject to this option
(“Shares”):
	  	As Per Carta
		
	 Option exercise price per share:
	  	As Per Carta
		
	 Number, if any, of Shares that vest immediately on the grant date:
	  	As Per Carta
		
	 Shares that are subject to vesting schedule:
	  	As Per Carta
		
	 Vesting Start Date:
	  	As Per Carta
		
	 Vesting Schedule (all vesting is dependent on the continuation of employment with the Company, as
provided herein):
	  	As Per Carta
		
	 Payment alternatives (specify any or all of Section 8(a)(i) through (iii)):
	  	Section 8(a)(i) through (iii)

 This option satisfies in full all commitments that the Company has to the Optionee with respect to the
issuance of stock, stock options or other equity securities. By signing below, the Optionee agrees to the terms and conditions set forth in this Agreement and in the Plan. 
  

									
		 		 	CYTEIR THERAPEUTICS, INC.
			
	 	 		 	By:
                                         
                                         
                                 
	 Signature of Optionee
	 		 	 Name of Officer: Markus Renschler

	 	 		 	 Title: President and CEO

	 Street Address
	 		 	
	 	 		 	
	 City/State/Zip Code
	 		 	

 CYTEIR THERAPEUTICS, INC. 

INCENTIVE STOCK OPTION AGREEMENT — 

INCORPORATED TERMS AND CONDITIONS 

1. Grant Under Plan. This option is granted pursuant to and is governed by the Company’s 2012 Stock Incentive Plan (as it may be
amended from time to time (the “Plan”) and, unless the context otherwise requires, terms used herein shall have the same meaning as in the Plan. 

2. Grant as Incentive Stock Option. This option is intended to qualify as an incentive stock option under Section 422 of the
Internal Revenue Code of 1986, as amended, and the regulations thereunder (the “Code”) and is granted to the Optionee in connection with the Optionee’s employment by the Company or a “subsidiary corporation” of the
Company, as such term is defined in Section 424 of the Code. 
 3. Vesting of Option. 

(a) Vesting if Employment Continues. The Optionee may exercise this option on or after the date of this option grant for
the number of shares of Common Stock, if any, that are then vested in accordance with the vesting schedule set forth on the cover page hereof. Notwithstanding the foregoing, the Board may, in its discretion, accelerate the date that any installment
of this option becomes exercisable. The foregoing rights are cumulative and may be exercised only before the Option Expiration Date set forth above. 

(b) Definitions. The following definitions shall apply: 

“Cause” means any of the following: (i) participation in or commission of any act that would constitute a
felony or a crime involving fraud, dishonesty, or moral turpitude under the laws of the United States or any state thereof; (ii) violation of any federal or state law or regulation applicable to the Company’s business that could result in
material harm to the Company or its operations; (iii) material violation of any agreement between the Optionee and the Company, any Company policy, or any statutory duty owed to the Company or its stockholders; (iv) an act of gross
misconduct or of clear and material insubordination; (v) commission or attempted commission of, or participation in, a fraud or act of dishonesty against the Company; (vi) persistent unsatisfactory performance or neglect of job duties; or
(vii) any unauthorized act that results in material harm to the Company’s business. If conduct constituting “Cause” under clause (iii) or (vi) above is reasonably susceptible of cure, Cause shall not exist unless the
Optionee is first given 30 days’ written notice to cure. 
 “Private Transaction” means any Acquisition
with respect to which less than 75% of the total consideration received or retained by the holders of the then outstanding capital stock of the Company consists of: (i) cash or cash equivalent consideration, (ii) securities which are
registered under the Securities Act and/or (iii) securities for which the Company or any other issuer thereof has agreed, including pursuant to a demand, to file a registration statement within ninety (90) days of completion of the
transaction for resale to the public pursuant to the Securities Act. 

 4. Termination of Employment. 

(a) Termination. Except as otherwise provided in Section 5, if the Optionee’s employment with the Company
ceases, voluntarily or involuntarily, with or without cause, no further installments of this option shall become exercisable, the portion of the option that is unvested at the time of cessation of such employment with the Company shall terminate,
and this option shall expire (may no longer be exercised) after the passage of three months from the date of termination, but in no event later than the Option Expiration Date. Any determination under this agreement as to employment status or other
matters referred to herein shall be made in good faith by the Board of Directors of the Company (the “Board”). The Optionee acknowledges that, except as provided in Section 5, this option will not be eligible for
“incentive stock option” tax treatment under the Code if it is exercised more than 90 days following Optionee’s termination of employment from the Company. 

(b) Employment Status. For purposes hereof, employment shall not be considered as having terminated during any leave of
absence if such leave of absence has been approved in writing by the Company and if such written approval contractually obligates the Company to continue the employment of the Optionee after the approved period of absence; in the event of such an
approved leave of absence, vesting of this option shall be suspended (and the period of the leave of absence shall be added to all vesting dates) unless otherwise provided in the Company’s written approval of the leave of absence. This option
shall not be affected by any change of employment within or among the Company and its Subsidiaries so long as the Optionee continuously remains an employee of the Company or any Subsidiary. 

(c) Termination for Cause. If the employment of the Optionee is terminated for Cause (as defined above), this option may
no longer be exercised from and after the Optionee’s receipt of written notice of such termination. In such event, the Repurchase Right described in Section 6 shall also be applicable. 

5. Death; Disability. 

(a) Death. Upon the death of the Optionee while the Optionee is employed with the Company, this option may be exercised,
to the extent otherwise exercisable on the date of the Optionee’s death, by the Optionee’s estate, personal representative or beneficiary to whom this option has been transferred pursuant to Section 11, only at any time within 180
days after the date of death, but not later than the Option Expiration Date. 
 (b) Disability. If the Optionee ceases
to maintain employment with the Company by reason of his or her disability, this option may be exercised, to the extent otherwise exercisable on the date of cessation of employment, only at any time within 180 days after such cessation of
employment, but not later than the Option Expiration Date. For purposes hereof, “disability” means “permanent and total disability” as defined in Section 22(e)(3) of the Code. 

  
 3 

 6. Company’s Right of Repurchase for Shares. 

(a) Right of Repurchase. The Company shall have the assignable right (the “Repurchase Right”) to
repurchase from the Optionee all, but not less than all, of the Shares purchased from the Company pursuant to this option, upon the occurrence of any of the events specified in Section 6(b) below (each, a “Repurchase Event”).
The Repurchase Right may be exercised within 60 days following the date the Company receives actual knowledge of such event (the “Repurchase Period”). The Repurchase Right shall be exercised by the Company by giving the Optionee
written notice on or before the last day of the Repurchase Period of its intention to exercise the Repurchase Right, and, together with such notice, tendering to the Optionee an amount (the “Repurchase Price”) equal to (i) in
the case of an event specified in Section 6(b)(i) or (ii) below, the fair market value of the Shares and (ii) in the case of an event specified in Section 6(b)(iii) or (iv) below, the lesser of the purchase price or the fair
market value of the Shares. Upon timely exercise of the Repurchase Right in the manner provided in this Section 6(a), the Optionee shall deliver to the Company or its assignee the stock certificate or certificates representing the shares being
repurchased, duly endorsed and free and clear of any and all liens, charges and encumbrances. 
 If Shares are not purchased under the
Repurchase Right, the Optionee and his or her successor in interest, if any, will hold any such Shares subject to all of the provisions of this Agreement. 

(b) Company’s Right to Exercise Repurchase Right. The Company or its assignee shall have the Repurchase Right in
the event that any of the following events shall occur: 
  

	 	(i)	 The receivership, bankruptcy or other creditor proceeding regarding the Optionee or the taking of any of
Optionee’s Shares by legal process, such as a levy of execution; 

  

	 	(ii)	 Distribution of Shares held by the Optionee to his or her spouse as such spouse’s joint or community
interest pursuant to a decree of dissolution, operation of law, divorce, property settlement agreement or for any other reason, except as may be otherwise permitted by the Company; 

 

	 	(iii)	 The termination of the Optionee’s employment for Cause (as defined in Section 3 hereof); or

  

	 	(iv)	 Within two years of the termination of the Optionee’s employment with the Company for any reason
whatsoever, the engagement by the Optionee, directly or indirectly, alone or with others, in (a) any business activity which is in competition with the Company or (b) the solicitation of, interference with or endeavor to entice away any
employee of the Company. 

  
 4 

 (c) Determination of Fair Market Value. The fair market value of the
Shares shall be, for purposes of this Section 6, determined by the Board in its sole discretion as of the date of the Repurchase Event. 

(d) Repurchase Procedure. Any repurchase of Shares by the Company shall take place at the principal executive offices of
the Company at the time and date set by the Company. Such sale shall be effected by the Optionee’s delivery to the Company of a certificate or certificates evidencing the repurchased Shares, duly endorsed for transfer to the Company, against
payment to the Optionee by the Company of the Repurchase Price by check for the repurchased Shares (which check may be delivered by mail) or by cancellation of indebtedness owed to the Company by the Optionee (after giving effect to any tax
consequences of such cancellation). Upon the mailing of a check in payment of the Repurchase Price in accordance with the terms hereof or cancellation of indebtedness as aforesaid, the Company shall become the legal and beneficial owner of the
Shares being repurchased and all rights and interests therein or relating thereto, and the Company shall have the right to retain and transfer to its own name the number of Shares being repurchased by the Company. 

(e) Expiration of Company’s Repurchase Right. The Repurchase Right shall remain in effect, subject to the
limitations set forth in the definition of “Repurchase Period” above, until such time, if ever, as the Common Stock of the Company is readily tradable on an established securities market. 

7. Exercise. This option may be exercised in part at any time and from time to time within the above limits, except that this option
may not be exercised for a fraction of a share. This option shall be exercised by completing and submitting to the Company the Stock Option Exercise Notice attached to this Agreement. 

8. Payment of Exercise Price. 

(a) Payment Options. The exercise price and any required withholding taxes may be paid by one or any combination of the
following forms of payment that are applicable to this option, as indicated on the cover page hereof: 
  

	 	(i)	 by check payable to the order of the Company; 

 

	 	(ii)	 if the Common Stock is then publicly traded, delivery of an irrevocable and unconditional undertaking,
satisfactory in form and substance to the Company, by a creditworthy broker to deliver promptly to the Company sufficient funds to pay the exercise price and any required tax withholding; or delivery by the Optionee to the Company of a copy of
irrevocable and unconditional instructions, satisfactory in form and substance to the Company, 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; or

  
 5 

	 	(iii)	 subject to Section 8(b) below, if the Common Stock is then traded on a national securities exchange or
another national trading system, by delivery of shares of Common Stock having a fair market value equal as of the date of exercise to the exercise price and any required tax withholding. 

In the case of (iii) above, fair market value as of the date of exercise shall be determined as of the last business day for which such
prices or quotes are available prior to the date of exercise and shall mean (i) the last reported sale price (on that date) of the Common Stock on the principal national securities exchange on which the Common Stock is traded, if the Common
Stock is then traded on a national securities exchange; or (ii) the last reported sale price (on that date) of the Common Stock on another national trading system, if the Common Stock is not then traded on a national securities exchange. 

(b) Limitations on Payment by Delivery of Common Stock. If Section 8(a)(iii) is applicable, and if the Optionee
delivers Common Stock held by the Optionee (“Old Stock”) to the Company in full or partial payment of the exercise price and required tax withholding and the Old Stock so delivered is subject to restrictions or limitations imposed
by agreement between the Optionee and the Company, a number of Shares shall be subject to all restrictions and limitations applicable to the Old Stock to the extent that the Optionee paid for the Shares by delivery of Old Stock, in addition to any
restrictions or limitations imposed by this Agreement. 
 9. Securities Laws Restrictions on Resale. Until registered under the
Securities Act of 1933, as amended, or any successor statute (the “Securities Act”), the Shares will be illiquid and will be deemed to be “restricted securities” for purposes of the Securities Act. Accordingly, such shares
must be sold in compliance with the registration requirements of the Securities Act or an exemption therefrom and may need to be held indefinitely. Unless the Shares have been registered under the Securities Act, each certificate evidencing any of
the Shares shall bear a restrictive legend specified by the Company. 
 10. Method of Exercising Option. Subject to the terms and
conditions of this agreement, this option may be exercised by written notice, in the form of the Stock Option Exercise Notice attached as Annex A, to the Company at its principal executive office, or to such transfer agent as the Company
shall designate. Such notice shall state the election to exercise this option and the number of Shares for which it is being exercised and shall be signed by the person or persons so exercising this option. Such notice shall be accompanied by
payment of the full purchase price of such shares, and the Company shall deliver a certificate or certificates representing such shares as soon as practicable after the notice shall be received. Such certificate or certificates shall be registered
in the name of the person or persons so exercising this option (or, if this option shall be exercised by the Optionee and if the Optionee shall so request in the notice exercising this option, shall be registered in the name of the Optionee and
another person jointly, with right of survivorship). In the event this option shall be exercised, pursuant to Section 5 hereof, by any person or persons other than the Optionee, such notice shall be accompanied by appropriate proof of the right
of such person or persons to exercise this option. 

  
 6 

 11. Option Not Transferable. This option is not transferable or assignable except by
will or by the laws of descent and distribution. During the Optionee’s lifetime only the Optionee can exercise this option. 
 12.
No Obligation to Exercise Option. The grant and acceptance of this option imposes no obligation on the Optionee to exercise it. 

13. No Obligation to Continue Employment. Neither the Plan, this agreement, nor the grant of this option imposes any obligation on the
Company to continue the Optionee in employment. 
 14. Withholding Taxes. If the Company in its discretion determines that it is
obligated to withhold any tax in connection with the exercise of this option, or in connection with the transfer of, or the lapse of restrictions on, any Common Stock or other property acquired pursuant to this option, the Optionee hereby agrees
that the Company may withhold from the Optionee’s wages or other remuneration the appropriate amount of tax. At the discretion of the Company, the amount required to be withheld may be withheld in cash from such wages or other remuneration or
in kind from the Common Stock or other property otherwise deliverable to the Optionee on exercise of this option. The Optionee further agrees that, if the Company does not withhold an amount from the Optionee’s wages or other remuneration
sufficient to satisfy the withholding obligation of the Company, the Optionee will make reimbursement on demand, in cash, for the amount under withheld. 

15. Restrictions on Transfer; Company’s Right of First Refusal. 

(a) Exercise of Right. Shares may not be transferred without the Company’s written consent except by will, by the
laws of descent and distribution or in accordance with the further provisions of this Section 15. If the Optionee desires to transfer all or any part of the Shares to any person other than the Company (an “Offeror”), the
Optionee shall: (i) obtain in writing an irrevocable and unconditional bona fide offer (the “Offer”) for the purchase thereof from the Offeror; and (ii) give written notice (the “Offer Notice”) to
the Company setting forth the Optionee’s desire to transfer such shares, which Offer Notice shall be accompanied by a photocopy of the Offer and shall set forth at least the name and address of the Offeror and the price and terms of the Offer.
Upon receipt of the Offer Notice, the Company shall have an assignable option to purchase any or all of such Shares (the “Offered Shares”) specified in the Offer Notice, such option to be exercisable by giving, within 15 days after
receipt of the Offer Notice, a written counter-notice to the Optionee. If the Company elects to purchase all of such Offered Shares, it shall be obligated to purchase, and the Optionee shall be obligated to sell to the Company or its assignee, such
Offered Shares at the price and terms indicated in the Offer within 30 days from the date of delivery by the Company of such counter-notice. To the extent that the consideration proposed to be paid by the Offeror for the shares consists of property
other than cash or a promissory note, the consideration required to be paid by the Company may consist of cash equal to the fair market value of such property, as determined in good faith by the Board. 

  
 7 

 (b) Sale of Shares to Offeror. The Optionee may, for 60 days after
the expiration of the 30-day option period as set forth in Section 15(a), sell to the Offeror, pursuant to the terms of the Offer, all of such Offered Shares not purchased or agreed to be purchased by the
Company or its assignee; provided, however, that the Optionee shall not sell such Shares to such Offeror if such Offeror is a competitor of the Company and the Company gives written notice to the Optionee, within 30 days of its receipt of the
Offer Notice, stating that the Optionee shall not sell his or her Shares to such Offeror; and provided, further, that prior to the sale of such Shares to an Offeror, such Offeror shall execute an agreement with the Company pursuant to which
such Offeror agrees to be subject to all of the restrictions applicable to the Optionee under this Agreement, including without limitation those set forth in Section 6 and this Section 15. If any or all of such Shares are not sold pursuant
to an Offer within the time permitted above, the unsold Shares shall remain subject to the terms of this Section 15. 

(c) Failure to Deliver Shares. If the Optionee (or his or her legal representative) who has become obligated to sell
Shares hereunder shall fail to deliver such shares to the Company in accordance with the terms of this agreement, the Company may, at its option, in addition to all other remedies it may have, mail to the Optionee the purchase price for such shares
as is herein specified. Thereupon, the Company: (i) shall cancel on its books the certificate or certificates representing such Shares to be sold; and (ii) shall issue, in lieu thereof, a new certificate or certificates in the name of the
Company representing such Shares (or cancel such Shares), and thereupon all of such Optionee’s rights in and to such Shares shall terminate. 

(d) Right of First Refusal and Co-Sale Agreement. The Optionee acknowledges that
the Company, the Optionee and certain future investors of the Company may become parties to a Right of First Refusal and Co-Sale Agreement (or another agreement with investor rights of first refusal and/or co-sale relating to transfers of shares by the Optionee, the “ROFR Agreement”), which will provide a right of first refusal in favor of investors with respect to the Shares. In the event of a
conflict between this Agreement and the ROFR Agreement, if any, the Company and the Optionee acknowledge and agree that the terms of the ROFR Agreement shall control and compliance with the ROFR Agreement shall be deemed compliance with this
Section 15 in full. 
 (e) Expiration of Company’s Right of First Refusal and Transfer Restrictions. The
first refusal rights of the Company and the transfer restrictions set forth in this Section 15 shall expire as to Shares on the earlier of: (i) immediately prior to the closing of a public offering of Common Stock by the Company pursuant
to an effective registration statement filed under the Securities Act, or (ii) the occurrence of an Acquisition that is not a Private Transaction. In addition, if the Company and the Optionee are parties to an agreement containing first refusal
provisions similar to the foregoing, such other agreement shall control and take precedence over this Agreement. 

  
 8 

 16. Early Disposition. The Optionee agrees to notify the Company in writing
immediately after the Optionee transfers any Shares, if such transfer occurs on or before the later of (a) the date that is two years after the date of this agreement or (b) the date that is one year after the date on which the Optionee
acquired such Shares. The Optionee also agrees to provide the Company with any information concerning any such transfer required by the Company for tax purposes. 

17. Annual Limit for Incentive Stock Options. To the extent that the aggregate fair market value (determined at the time of grant) of
the Shares subject to this option and all other incentive stock options the Optionee holds that are exercisable for the first time during any calendar year (under all plans of the Company and its related corporations) exceeds $100,000, the options
held by the Optionee or portions thereof that exceed such limit (according to the order in which they were granted in accordance with the regulations under Section 422 of the Code) shall be treated as nonqualified stock options. 

18. Lock-up Agreement. The Optionee agrees that in the event that the Company effects an
initial underwritten public offering of Common Stock registered under the Securities Act, the Shares may not be sold, offered for sale or otherwise disposed of, directly or indirectly, without the prior written consent of the managing underwriter(s)
of the offering, for such period of time after the execution of an underwriting agreement in connection with such offering that all of the Company’s then directors and executive officers agree to be similarly bound. 

19. Arbitration. Any dispute, controversy, or claim arising out of, in connection with, or relating to the performance of this
agreement or its termination shall be settled by arbitration by a single arbitrator in the Commonwealth of Massachusetts, pursuant to the rules then obtaining of the American Arbitration Association. Any award shall be final, binding and conclusive
upon the parties and a judgment rendered thereon may be entered in any court having jurisdiction thereof. 
 20. Provision of
Documentation to Optionee. By signing this agreement the Optionee acknowledges receipt of a copy of this Agreement and a copy of the Plan. 

21. Miscellaneous. 

(a) Notices. All notices hereunder shall be in writing and shall be deemed given when sent by mail, if to the Optionee,
to the address set forth below or at the address shown on the records of the Company, and if to the Company, to the Company’s principal executive offices, attention of the Corporate Secretary. 

(b) Entire Agreement; Modification. Subject to Section 1 above, this agreement constitutes the entire agreement
between the parties relative to the subject matter hereof, and supersedes all proposals, written or oral, and all other communications between the parties relating to the subject matter of this agreement. This agreement may be modified, amended or
rescinded only by a written agreement executed by both parties. 
 (c) Fractional Shares. If this option becomes
exercisable for a fraction of a share because of the adjustment provisions contained in the Plan, such fraction shall be rounded down. 

  
 9 

 (d) Issuances of Securities; Changes in Capital Structure. Except as
expressly provided herein or in the Plan, no issuance by the Company of shares of stock of any class, or securities convertible into shares of stock of any class, shall affect, and no adjustment by reason thereof shall be made with respect to, the
number or price of shares subject to this option. No adjustments need be made for dividends paid in cash or in property other than securities of the Company. If there shall be any change in the Common Stock of the Company through merger,
consolidation, reorganization, recapitalization, stock dividend, stock split, combination or exchange of shares, spin-off, split-up or other similar change in
capitalization or event, the restrictions contained in this agreement shall apply with equal force to additional and/or substitute securities, if any, received by the Optionee in exchange for, or by virtue of his or her ownership of, Shares, except
as otherwise determined by the Board. 
 (e) Tax Treatment. Although it is the intention of the Company that this
option shall qualify as an incentive stock option under the Code, the Company cannot guarantee that this will be the case. The Company will have no liability to the Optionee if this option fails to qualify as an incentive stock option. 

(f) Severability. The invalidity, illegality or unenforceability of any provision of this agreement shall in no way
affect the validity, legality or enforceability of any other provision. 
 (g) Successors and Assigns. This agreement
shall be binding upon and inure to the benefit of the parties hereto and their respective successors and assigns, subject to the limitations set forth in Section 11 hereof. 

(h) Governing Law. This agreement shall be governed by and interpreted in accordance with the laws of the State of
Delaware, without giving effect to the principles of the conflicts of laws thereof. 

  
 10 

 ANNEX A 

CYTEIR THERAPEUTICS, INC. 

Stock Option Exercise Notice 
 Cyteir
Therapeutics, Inc. 
 128 Spring Street 
 Lexington, MA 02421

 Dear Sir or Madam: 
 I, ________________
(the “Optionee”), hereby irrevocably exercise the right to purchase1 shares of the Common Stock, $.001 par value per share (the “Shares”), of Cyteir Therapeutics,
Inc. (the “Company”) at $__________2 per share pursuant to the Company’s 2012 Stock Incentive Plan, as amended, and a stock option agreement with the Company dated
_________________3 (the “Option Agreement”), which is designated with Security No._______4 in Carta (if applicable). Enclosed
herewith is a payment of $_____________5 the aggregate purchase price for the Shares. The certificate for the Shares should be registered in my name as it appears below or, if so indicated below,
jointly in my name and the name of the person designated below, with right of survivorship. 
 I acknowledge and agree that the Option
Agreement remains in full force and effect and includes a number of restrictions on the Shares, including certain rights of the Company to repurchase Shares under certain circumstances as set forth in Section 6 of the Option Agreement, and on
the transfer of the Shares, including, but not limited to, certain rights of first refusal on the transfer of all or any part of the Shares as set forth in Section 15 of the Option Agreement. 

Further, I understand that the Shares have not been registered under the Securities Act of 1933, as amended, or any state securities laws. As
a result, I understand that I must continue to bear the economic risk of the investment for an indefinite time and that the Shares cannot be sold unless they are subsequently registered or an exemption from registration is available. 

Dated: ______________________6 

__________________________________________ 
 Signature 

 

	1 	 Enter the number of shares of Common Stock to be purchased upon exercise of all or part of the option.

	2 	 Enter the option exercise price per share of Common Stock. 

	3 	 Enter the date of grant. 

	4 	 Enter Carta Security No. (if applicable). 

	5 	 Enter the dollar amount (price per share of Common Stock times the number of shares of Common Stock to be
purchased). 

	6 	 Enter date of exercise. 

 Print Name: 

__________________________________________ 
 Address: 

 __________________________________________ 

__________________________________________ 
 Name and address of
persons in whose name the Shares are to be jointly registered (if applicable): 
 __________________________________________ 

  
 12

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00328-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00328-of-00352.parquet"}]]