EX-10.3





 Exhibit 10.3 

SYNTHORX, INC. 

2018 EQUITY INCENTIVE PLAN 

ADOPTED BY THE BOARD OF DIRECTORS:
NOVEMBER 19, 2018 
 APPROVED BY THE STOCKHOLDERS:
NOVEMBER 26, 2018 
 IPO DATE: [           ], 2018

  

	1.	 GENERAL. 



(a)        Successor to and Continuation of Prior Plan. The Plan is
intended as the successor to and continuation of the Synthorx, Inc. 2014 Equity Incentive Plan (the “Prior Plan”). From and after 12:01 a.m. Pacific Time on the IPO Date, no additional stock awards will be granted under the
Prior Plan. All Awards granted on or after 12:01 a.m. Pacific Time on the IPO Date will be granted under this Plan. All stock awards granted under the Prior Plan will remain subject to the terms of the Prior Plan. 

(i)        Any shares that would otherwise remain available for future grants
under the Prior Plan as of 12:01 a.m. Pacific Time on the IPO Date (the “Prior Plan’s Available Reserve”) will cease to be available under the Prior Plan at such time. Instead, that number of shares of Common Stock equal
to the Prior Plan’s Available Reserve will be added to the Share Reserve (as further described in Section 3(a) below) and will be immediately available for grants and issuance pursuant to Stock Awards hereunder, up to the maximum number
set forth in Section 3(a) below. 
 (ii)        In addition, from and
after 12:01 a.m. Pacific Time on the IPO Date, any shares subject, at such time, to outstanding stock awards granted under the Prior Plan that (i) expire or terminate for any reason prior to exercise or settlement; (ii) are forfeited
because of the failure to meet a contingency or condition required to vest such shares or otherwise return to the Company; or (iii) are reacquired, withheld (or not issued) to satisfy a tax withholding obligation in connection with an award or
to satisfy the purchase price or exercise price of a stock award (such shares the “Returning Shares”) will immediately be added to the Share Reserve (as further described in Section 3(a) below) as and when such shares
become Returning Shares, up to the maximum number set forth in Section 3(a) below. 

(b)        Eligible Award Recipients. Employees, Directors and
Consultants are eligible to receive Awards. 
 (c)        Available
Awards. The Plan provides for the grant of the following types of Awards: (i) Incentive Stock Options, (ii) Nonstatutory Stock Options, (iii) Stock Appreciation Rights (iv) Restricted Stock Awards, (v) Restricted Stock
Unit Awards, (vi) Performance Stock Awards, (vii) Performance Cash Awards, and (viii) Other Stock Awards. 

(d)        Purpose. The Plan, through the granting of Awards, is
intended to help the Company secure and retain the services of eligible award recipients, provide incentives for such persons to exert maximum efforts for the success of the Company and any Affiliate and provide a means by which the eligible
recipients may benefit from increases in value of the Common Stock. 
  

	2.	 ADMINISTRATION. 



(a)        Administration by Board. The Board will administer the Plan.
The Board may delegate administration of the Plan to a Committee or Committees, as provided in Section 2(c). 

  
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(b)          Powers of Board. The Board will have the power,
subject to, and within the limitations of, the express provisions of the Plan: 

(i)        To determine (A) who will be granted Awards; (B) when and
how each Award will be granted; (C) what type of Award will be granted; (D) the provisions of each Award (which need not be identical), including when a person will be permitted to exercise or otherwise receive cash or Common Stock under
the Award; (E) the number of shares of Common Stock subject to, or the cash value of, an Award; and (F) the Fair Market Value applicable to a Stock Award. 

(ii)        To construe and interpret the Plan and Awards granted under it,
and to establish, amend and revoke rules and regulations for administration of the Plan and Awards. The Board, in the exercise of these powers, may correct any defect, omission or inconsistency in the Plan or in any Award Agreement or in the written
terms of a Performance Cash Award, in a manner and to the extent it will deem necessary or expedient to make the Plan or Award fully effective. 

(iii)        To settle all controversies regarding the Plan and Awards granted
under it. 
 (iv)        To accelerate, in whole or in part, the time at
which an Award may be exercised or vest (or the time at which cash or shares of Common Stock may be issued in settlement thereof). 

(v)        To suspend or terminate the Plan at any time. Except as otherwise
provided in the Plan or an Award Agreement, suspension or termination of the Plan will not materially impair a Participant’s rights under the Participant’s then-outstanding Award without the Participant’s written consent except as
provided in subsection (viii) below. 
 (vi)        To amend the Plan
in any respect the Board deems necessary or advisable, including, without limitation, by adopting amendments relating to Incentive Stock Options and certain nonqualified deferred compensation under Section 409A of the Code and/or bringing the
Plan or Awards granted under the Plan into compliance with the requirements for Incentive Stock Options or ensuring that they are exempt from or compliant with the requirements for nonqualified deferred compensation under Section 409A of the
Code, subject to the limitations, if any, of applicable law. If required by applicable law or listing requirements, and except as provided in Section 9(a) relating to Capitalization Adjustments, the Company will seek stockholder approval of any
amendment of the Plan that (A) materially increases the number of shares of Common Stock available for issuance under the Plan, (B) materially expands the class of individuals eligible to receive Awards under the Plan, (C) materially
increases the benefits accruing to Participants under the Plan, (D) materially reduces the price at which shares of Common Stock may be issued or purchased under the Plan, (E) materially extends the term of the Plan, or (F) materially
expands the types of Awards available for issuance under the Plan. Except as otherwise provided in the Plan or an Award Agreement, no amendment of the Plan will materially impair a Participant’s rights under an outstanding Award without the
Participant’s written consent. 
 (vii)        To submit any amendment
to the Plan for stockholder approval, including, but not limited to, amendments to the Plan intended to satisfy the requirements of (A) Section 422 of the Code regarding incentive stock options or (B) Rule 16b-3. 
 (viii)        To approve forms
of Award Agreements for use under the Plan and to amend the terms of any one or more Awards, including, but not limited to, amendments to provide terms more favorable to the Participant than previously provided in the Award Agreement, subject to any
specified limits in the Plan that are not subject to Board discretion; provided however, that a Participant’s rights under any Award will not be impaired by any such amendment unless (A) the Company requests the consent of the
affected Participant, and (B) such Participant consents in writing. Notwithstanding the foregoing, (1) a 

  
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Participant’s rights will not be deemed to have been impaired by any such amendment if the Board, in its sole discretion, determines that the amendment, taken as a whole, does not materially
impair the Participant’s rights, and (2) subject to the limitations of applicable law, if any, the Board may amend the terms of any one or more Awards without the affected Participant’s consent (A) to maintain the qualified
status of the Award as an Incentive Stock Option under Section 422 of the Code; (B) to change the terms of an Incentive Stock Option, if such change results in impairment of the Award solely because it impairs the qualified status of the
Award as an Incentive Stock Option under Section 422 of the Code; (C) to clarify the manner of exemption from, or to bring the Award into compliance with, Section 409A of the Code; or (D) to comply with other applicable laws or
listing requirements. 
 (ix)        Generally, to exercise such powers and
to perform such acts as the Board deems necessary or expedient to promote the best interests of the Company and that are not in conflict with the provisions of the Plan or Awards. 

(x)        To adopt such procedures and
sub-plans as are necessary or appropriate to permit participation in the Plan by Employees, Directors or Consultants who are foreign nationals or employed outside the United States (provided that Board
approval will not be necessary for immaterial modifications to the Plan or any Award Agreement that are required for compliance with the laws of the relevant foreign jurisdiction). 

(xi)        To effect, with the consent of any adversely affected Participant,
(A) the reduction of the exercise, purchase or strike price of any outstanding Stock Award; (B) the cancellation of any outstanding Stock Award and the grant in substitution therefor of a new (1) Option or SAR, (2) Restricted
Stock Award, (3) Restricted Stock Unit Award, (4) Other Stock Award, (5) cash and/or (6) other valuable consideration determined by the Board, in its sole discretion, with any such substituted award (x) covering the same or
a different number of shares of Common Stock as the cancelled Stock Award and (y) granted under the Plan or another equity or compensatory plan of the Company; or (C) any other action that is treated as a repricing under generally accepted
accounting principles. 
 (c)            Delegation to
Committee. 
 (i)        General. The Board may
delegate some or all of the administration of the Plan to a Committee or Committees. If administration of the Plan is delegated to a Committee, the Committee will have, in connection with the administration of the Plan, the powers theretofore
possessed by the Board that have been delegated to the Committee, including the power to delegate to a subcommittee of the Committee any of the administrative powers the Committee is authorized to exercise (and references in this Plan to the Board
will thereafter be to the Committee or subcommittee, as applicable). Any delegation of administrative powers will be reflected in resolutions, not inconsistent with the provisions of the Plan, adopted from time to time by the Board or Committee (as
applicable). The Committee may, at any time, abolish the subcommittee and/or revest in the Committee any powers delegated to the subcommittee. The Board may retain the authority to concurrently administer the Plan with the Committee and may, at any
time, revest in the Board some or all of the powers previously delegated. 

(ii)        Rule 16b-3
Compliance. The Committee may consist solely of two or more Non-Employee Directors, in accordance with Rule 16b-3. 

(d)            Delegation to an Officer. The
Board may delegate to one or more Officers the authority to do one or both of the following (i) designate Employees who are not Officers to be recipients of Options and SARs (and, to the extent permitted by applicable law, other Stock Awards)
and, to the extent permitted by applicable law, the terms of such Awards, and (ii) determine the number of shares of Common Stock to be subject to such Stock Awards granted to such Employees; provided, however, that the Board resolutions


  
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regarding such delegation will specify the total number of shares of Common Stock that may be subject to the Stock Awards granted by such Officer and that such Officer may not grant a Stock Award
to himself or herself. Any such Stock Awards will be granted on the form of Stock Award Agreement most recently approved for use by the Committee or the Board, unless otherwise provided in the resolutions approving the delegation authority. The
Board may not delegate authority to an Officer who is acting solely in the capacity of an Officer (and not also as a Director) to determine the Fair Market Value pursuant to Section 13(w)(iii) below. 

(e)        Effect of Board’s Decision. All determinations,
interpretations and constructions made by the Board in good faith will not be subject to review by any person and will be final, binding and conclusive on all persons. 
  

	3.	 SHARES SUBJECT TO THE PLAN.



 (a)        Share Reserve. Subject to
Section 9(a) relating to Capitalization Adjustments, and the following sentence regarding the annual increase, the aggregate number of shares of Common Stock that may be issued pursuant to Stock Awards will not exceed 5,828,865 shares (the
“Share Reserve”), which number is the sum of (i) 3,428,492 new shares, plus (ii) the number of shares subject to the Prior Plan’s Available Reserve plus (iii) the number of shares that are
Returning Shares, as such shares become available from time to time. In addition, the Share Reserve will automatically increase on January 1st of each year, for a period of not more than ten
years, commencing on January 1st of the year following the year in which the IPO Date occurs and ending on (and including) January 1, 2028, in an amount equal to 4% of the total number of
shares of Capital Stock outstanding on December 31st of the preceding calendar year. Notwithstanding the foregoing, the Board may act prior to January 1st of a given year to provide that there
will be no January 1st increase in the Share Reserve for such year or that the increase in the Share Reserve for such year will be a lesser number of shares of Common Stock than would otherwise
occur pursuant to the preceding sentence. 
 For clarity, the Share Reserve in this Section 3(a) is a limitation on the
number of shares of Common Stock that may be issued pursuant to the Plan. Accordingly, this Section 3(a) does not limit the granting of Stock Awards except as provided in Section 7(a). Shares may be issued in connection with a merger or
acquisition as permitted by Nasdaq Listing Rule 5635(c) or, if applicable, NYSE Listed Company Manual Section 303A.08, AMEX Company Guide Section 711 or other applicable rule, and such issuance will not reduce the number of shares
available for issuance under the Plan. 
 (b)        Reversion of Shares
to the Share Reserve. If a Stock Award or any portion thereof (i) expires or otherwise terminates without all of the shares covered by such Stock Award having been issued or (ii) is settled in cash (i.e., the Participant
receives cash rather than stock), such expiration, termination or settlement will not reduce (or otherwise offset) the number of shares of Common Stock that may be available for issuance under the Plan. If any shares of Common Stock issued pursuant
to a Stock Award are forfeited back to or repurchased or reacquired by the Company for any reason, including because of the failure to meet a contingency or condition required to vest such shares in the Participant, then the shares that are
forfeited or repurchased or reacquired will revert to and again become available for issuance under the Plan. Any shares reacquired by the Company in satisfaction of tax withholding obligations on a Stock Award or as consideration for the exercise
or purchase price of a Stock Award will again become available for issuance under the Plan. 

(c)        Incentive Stock Option Limit. Subject to the Share Reserve
and Section 9(a) relating to Capitalization Adjustments, the aggregate maximum number of shares of Common Stock that may be issued pursuant to the exercise of Incentive Stock Options will be 11,657,730 shares of Common Stock.  

  
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 (d)        Source of
Shares. The stock issuable under the Plan will be shares of authorized but unissued or reacquired Common Stock, including shares repurchased by the Company on the open market or otherwise. 

 

	4.	 ELIGIBILITY. 



(a)        Eligibility for Specific Stock Awards. Incentive Stock
Options may be granted only to employees of the Company or a “parent corporation” or “subsidiary corporation” thereof (as such terms are defined in Sections 424(e) and 424(f) of the Code). Stock Awards other than Incentive Stock
Options may be granted to Employees, Directors and Consultants; provided, however, that Stock Awards may not be granted to Employees, Directors and Consultants who are providing Continuous Service only to any “parent” of the Company, as
such term is defined in Rule 405 of the Securities Act, unless (i) the stock underlying such Stock Awards is treated as “service recipient stock” under Section 409A of the Code (for example, because the Stock Awards are granted
pursuant to a corporate transaction such as a spin off transaction), (ii) the Company, in consultation with its legal counsel, has determined that such Stock Awards are otherwise exempt from Section 409A of the Code, or (iii) the Company,
in consultation with its legal counsel, has determined that such Stock Awards comply with the distribution requirements of Section 409A of the Code. 

(b)        Ten Percent Stockholders. A Ten Percent Stockholder will not
be granted an Incentive Stock Option unless the exercise price of such Option is at least 110% of the Fair Market Value on the date of grant and the Option is not exercisable after the expiration of five years from the date of grant. 

 

	5.	 PROVISIONS RELATING TO OPTIONS
AND STOCK APPRECIATION RIGHTS. 


 Each
Option or SAR will be in such form and will contain such terms and conditions as the Board deems appropriate. All Options will be separately designated Incentive Stock Options or Nonstatutory Stock Options at the time of grant, and, if certificates
are issued, a separate certificate or certificates will be issued for shares of Common Stock purchased on exercise of each type of Option. If an Option is not specifically designated as an Incentive Stock Option, or if an Option is designated as an
Incentive Stock Option but some portion or all of the Option fails to qualify as an Incentive Stock Option under the applicable rules, then the Option (or portion thereof) will be a Nonstatutory Stock Option. The provisions of separate Options or
SARs need not be identical; provided, however, that each Award Agreement will conform to (through incorporation of provisions hereof by reference in the applicable Award Agreement or otherwise) the substance of each of the following
provisions: 
 (a)        Term. Subject to the provisions of
Section 4(b) regarding Ten Percent Stockholders, no Option or SAR will be exercisable after the expiration of ten (10) years from the date of its grant or such shorter period specified in the Award Agreement. 

(b)        Exercise Price. Subject to the provisions of
Section 4(b) regarding Ten Percent Stockholders, the exercise or strike price of each Option or SAR will be not less than 100% of the Fair Market Value of the Common Stock subject to the Option or SAR on the date the Award is granted.
Notwithstanding the foregoing, an Option or SAR may be granted with an exercise or strike price lower than 100% of the Fair Market Value of the Common Stock subject to the Award if such Award is granted pursuant to an assumption of or substitution
for another option or stock appreciation right pursuant to a corporate transaction and in a manner consistent with the provisions of Section 409A of the Code and, if applicable, Section 424(a) of the Code. Each SAR will be denominated in
shares of Common Stock equivalents. 

  
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(c)          Purchase Price for Options. The purchase price of
Common Stock acquired pursuant to the exercise of an Option may be paid, to the extent permitted by applicable law and as determined by the Board in its sole discretion, by any combination of the methods of payment set forth below. The Board will
have the authority to grant Options that do not permit all of the following methods of payment (or otherwise restrict the ability to use certain methods) and to grant Options that require the consent of the Company to use a particular method of
payment. The permitted methods of payment are as follows: 
 (i)        by
cash, check, bank draft or money order payable to the Company; 

(ii)        pursuant to a program developed under Regulation T as promulgated
by the Federal Reserve Board that, prior to the issuance of the stock subject to the Option, results in either the receipt of cash (or check) by the Company or the receipt of irrevocable instructions to pay the aggregate exercise price to the
Company from the sales proceeds; 
 (iii)        by delivery to the Company
(either by actual delivery or attestation) of shares of Common Stock; 

(iv)        if an Option is a Nonstatutory Stock Option, by a “net
exercise” arrangement pursuant to which the Company will reduce the number of shares of Common Stock issuable upon exercise by the largest whole number of shares with a Fair Market Value that does not exceed the aggregate exercise price;
provided, however, that the Company will accept a cash or other payment from the Participant to the extent of any remaining balance of the aggregate exercise price not satisfied by such reduction in the number of whole shares to be issued.
Shares of Common Stock will no longer be subject to an Option and will not be exercisable thereafter to the extent that (A) shares issuable upon exercise are used to pay the exercise price pursuant to the “net exercise,” (B) shares
are delivered to the Participant as a result of such exercise, and (C) shares are withheld to satisfy tax withholding obligations; or 

(v)        in any other form of legal consideration that may be acceptable to
the Board and specified in the applicable Award Agreement. 

(d)          Exercise and Payment of a SAR. To exercise any
outstanding SAR, the Participant must provide written notice of exercise to the Company in compliance with the provisions of the Stock Appreciation Right Agreement evidencing such SAR. The appreciation distribution payable on the exercise of a SAR
will be not greater than an amount equal to the excess of (A) the aggregate Fair Market Value (on the date of the exercise of the SAR) of a number of shares of Common Stock equal to the number of Common Stock equivalents in which the
Participant is vested under such SAR, and with respect to which the Participant is exercising the SAR on such date, over (B) the aggregate strike price of the number of Common Stock equivalents with respect to which the Participant is
exercising the SAR on such date. The appreciation distribution may be paid in Common Stock, in cash, in any combination of the two or in any other form of consideration, as determined by the Board and contained in the Award Agreement evidencing such
SAR. 
 (e)          Transferability of Options and SARs.
The Board may, in its sole discretion, impose such limitations on the transferability of Options and SARs as the Board will determine. In the absence of such a determination by the Board to the contrary, the following restrictions on the
transferability of Options and SARs will apply: 

(i)        Restrictions on Transfer. An Option or SAR
will not be transferable except by will or by the laws of descent and distribution (or pursuant to subsections (ii) and (iii) below), and will be exercisable during the lifetime of the Participant only by the Participant. The Board may permit
transfer of 

  
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the Option or SAR in a manner that is not prohibited by applicable tax and securities laws. Except as explicitly provided herein, neither an Option nor a SAR may be transferred for consideration.

 (ii)        Domestic Relations Orders. Subject to the approval of
the Board or a duly authorized Officer, an Option or SAR may be transferred pursuant to the terms of a domestic relations order, official marital settlement agreement or other divorce or separation instrument as permitted by Treasury Regulation Section 1.421-1(b)(2). If an Option is an Incentive Stock Option, such Option may be deemed to be a Nonstatutory Stock Option as a result of such transfer. 

(iii)        Beneficiary Designation. Subject to the approval of the
Board or a duly authorized Officer, a Participant may, by delivering written notice to the Company, in a form approved by the Company (or the designated broker), designate a third party who, on the death of the Participant, will thereafter be
entitled to exercise the Option or SAR and receive the Common Stock or other consideration resulting from such exercise. In the absence of such a designation, upon the death of the Participant, the executor or administrator of the Participant’s
estate will be entitled to exercise the Option or SAR and receive the Common Stock or other consideration resulting from such exercise. However, the Company may prohibit designation of a beneficiary at any time, including due to any conclusion by
the Company that such designation would be inconsistent with the provisions of applicable laws. 

(f)          Vesting Generally. The total number of shares of
Common Stock subject to an Option or SAR may vest and become exercisable in periodic installments that may or may not be equal. The Option or SAR may be subject to such other terms and conditions on the time or times when it may or may not be
exercised (which may be based on the satisfaction of Performance Goals or other criteria) as the Board may deem appropriate. The vesting provisions of individual Options or SARs may vary. The provisions of this Section 5(f) are subject to any
Option or SAR provisions governing the minimum number of shares of Common Stock as to which an Option or SAR may be exercised. 

(g)          Termination of Continuous Service. Except as
otherwise provided in the applicable Award Agreement or other agreement between the Participant and the Company, if a Participant’s Continuous Service terminates (other than for Cause and other than upon the Participant’s death or
Disability), the Participant may exercise his or her Option or SAR (to the extent that the Participant was entitled to exercise such Award as of the date of termination of Continuous Service) within the period of time ending on the earlier of
(i) the date that is three (3) months following the termination of the Participant’s Continuous Service (or such longer or shorter period specified in the applicable Award Agreement, which period will not be less than thirty
(30) days if necessary to comply with applicable laws unless such termination is for Cause) and (ii) the expiration of the term of the Option or SAR as set forth in the Award Agreement. If, after termination of Continuous Service, the
Participant does not exercise his or her Option or SAR (as applicable) within the applicable time frame, the Option or SAR will terminate. 

(h)          Extension of Termination Date. Except as
otherwise provided in the applicable Award Agreement or other written agreement between the Participant and the Company, if the exercise of an Option or SAR following the termination of the Participant’s Continuous Service (other than for Cause
and other than upon the Participant’s death or Disability) would be prohibited at any time solely because the issuance of shares of Common Stock would violate the registration requirements under the Securities Act, then the Option or SAR will
terminate on the earlier of (i) the expiration of a total period of time (that need not be consecutive) equal to the applicable post termination exercise period after the termination of the Participant’s Continuous Service during which the
exercise of the Option or SAR would not be in violation of such registration requirements, and (ii) the expiration of the term of the Option or SAR as set forth in the applicable Award Agreement. In addition, unless otherwise provided in a
Participant’s Award Agreement, if the sale of any Common Stock received on exercise of an Option or SAR following the termination of the Participant’s Continuous Service (other than for Cause) would violate the Company’s insider
trading 

  
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policy, then the Option or SAR will terminate on the earlier of (i) the expiration of a period of months (that need not be consecutive) equal to the applicable post-termination exercise
period after the termination of the Participant’s Continuous Service during which the sale of the Common Stock received upon exercise of the Option or SAR would not be in violation of the Company’s insider trading policy, or (ii) the
expiration of the term of the Option or SAR as set forth in the applicable Award Agreement. 

(i)        Disability of Participant. Except as otherwise
provided in the applicable Award Agreement or other agreement between the Participant and the Company, if a Participant’s Continuous Service terminates as a result of the Participant’s Disability, the Participant may exercise his or her
Option or SAR (to the extent that the Participant was entitled to exercise such Option or SAR as of the date of termination of Continuous Service), but only within such period of time ending on the earlier of (i) the date twelve
(12) months following such termination of Continuous Service (or such longer or shorter period specified in the Award Agreement, which period will not be less than six (6) months if necessary to comply with applicable laws) and
(ii) the expiration of the term of the Option or SAR as set forth in the Award Agreement. If, after termination of Continuous Service, the Participant does not exercise his or her Option or SAR within the applicable time frame, the Option or
SAR (as applicable) will terminate. 
 (j)        Death of
Participant. Except as otherwise provided in the applicable Award Agreement or other agreement between the Participant and the Company, if (i) a Participant’s Continuous Service terminates as a result of the Participant’s death,
or (ii) the Participant dies within the period (if any) specified in the Award Agreement for exercisability after the termination of the Participant’s Continuous Service for a reason other than death, then the Option or SAR may be
exercised (to the extent the Participant was entitled to exercise such Option or SAR as of the date of death) by the Participant’s estate, by a person who acquired the right to exercise the Option or SAR by bequest or inheritance or by a person
designated to exercise the Option or SAR upon the Participant’s death, but only within the period ending on the earlier of (i) the date eighteen (18) months following the date of death (or such longer or shorter period specified in
the Award Agreement, which period will not be less than six (6) months if necessary to comply with applicable laws) and (ii) the expiration of the term of such Option or SAR as set forth in the Award Agreement. If, after the
Participant’s death, the Option or SAR is not exercised within the applicable time frame, the Option or SAR (as applicable) will terminate. 

(k)        Termination for Cause. Except as explicitly provided
otherwise in a Participant’s Award Agreement or other individual written agreement between the Company or any Affiliate and the Participant, if a Participant’s Continuous Service is terminated for Cause, the Option or SAR will terminate
immediately upon such Participant’s termination of Continuous Service, and the Participant will be prohibited from exercising his or her Option or SAR from and after the time of such termination of Continuous Service. 

(l)        Non-Exempt Employees.
If an Option or SAR is granted to an Employee who is a non-exempt employee for purposes of the Fair Labor Standards Act of 1938, as amended, the Option or SAR will not be first exercisable for any shares of
Common Stock until at least six (6) months following the date of grant of the Option or SAR (although the Award may vest prior to such date). Consistent with the provisions of the Worker Economic Opportunity Act, (i) if such non-exempt Employee dies or suffers a Disability, (ii) upon a Corporate Transaction in which such Option or SAR is not assumed, continued, or substituted, (iii) upon a Change in Control, or (iv) upon
the Participant’s retirement (as such term may be defined in the Participant’s Award Agreement, in another agreement between the Participant and the Company, or, if no such definition, in accordance with the Company’s then current
employment policies and guidelines), the vested portion of any Options and SARs may be exercised earlier than six (6) months following the date of grant. The foregoing provision is intended to operate so that any income derived by a non-exempt employee in connection with the exercise or vesting of an Option or SAR will be exempt from his or her regular rate of pay. To the extent permitted and/or required for compliance with the Worker Economic
Opportunity Act to ensure that any income derived by a non-exempt employee in connection 

  
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with the exercise, vesting or issuance of any shares under any other Stock Award will be exempt from the employee’s regular rate of pay, the provisions of this Section 5(l) will apply
to all Stock Awards and are hereby incorporated by reference into such Stock Award Agreements. 
  

	6.	 PROVISIONS OF STOCK AWARDS
OTHER THAN OPTIONS AND SARS. 



(a)          Restricted Stock Awards. Each Restricted Stock
Award Agreement will be in such form and will contain such terms and conditions as the Board deems appropriate. To the extent consistent with the Company’s bylaws, at the Board’s election, shares of Common Stock may be (i) held in
book entry form subject to the Company’s instructions until any restrictions relating to the Restricted Stock Award lapse; or (ii) evidenced by a certificate, which certificate will be held in such form and manner as determined by the
Board. The terms and conditions of Restricted Stock Award Agreements may change from time to time, and the terms and conditions of separate Restricted Stock Award Agreements need not be identical. Each Restricted Stock Award Agreement will conform
to (through incorporation of the provisions hereof by reference in the agreement or otherwise) the substance of each of the following provisions: 

(i)        Consideration. A Restricted Stock Award may be awarded in
consideration for (A) cash, check, bank draft or money order payable to the Company, (B) past or future services to the Company or an Affiliate, or (C) any other form of legal consideration that may be acceptable to the Board, in its
sole discretion, and permissible under applicable law. 

(ii)        Vesting. Shares of Common Stock awarded under the
Restricted Stock Award Agreement may be subject to forfeiture to the Company in accordance with a vesting schedule to be determined by the Board. 

(iii)        Termination of Participant’s Continuous Service. If a
Participant’s Continuous Service terminates, the Company may receive through a forfeiture condition or a repurchase right any or all of the unvested shares of Common Stock held by the Participant as of the date of termination of Continuous
Service under the terms of the Restricted Stock Award Agreement. 

(iv)        Transferability. Rights to acquire shares of Common Stock
under the Restricted Stock Award Agreement will be transferable by the Participant only upon such terms and conditions as are set forth in the Restricted Stock Award Agreement, as the Board will determine in its sole discretion, so long as Common
Stock awarded under the Restricted Stock Award Agreement remains subject to the terms of the Restricted Stock Award Agreement. 

(v)        Dividends. A Restricted Stock Award Agreement may provide
that any dividends paid on Restricted Stock will be subject to the same vesting and forfeiture restrictions as apply to the shares subject to the Restricted Stock Award to which they relate. 

(b)          Restricted Stock Unit Awards. Each Restricted
Stock Unit Award Agreement will be in such form and will contain such terms and conditions as the Board deems appropriate. The terms and conditions of Restricted Stock Unit Award Agreements may change from time to time, and the terms and conditions
of separate Restricted Stock Unit Award Agreements need not be identical. Each Restricted Stock Unit Award Agreement will conform to (through incorporation of the provisions hereof by reference in the Agreement or otherwise) the substance of each of
the following provisions: 
 (i)        Consideration.
At the time of grant of a Restricted Stock Unit Award, the Board will determine the consideration, if any, to be paid by the Participant upon delivery of each share of Common Stock subject to the Restricted Stock Unit Award. The consideration to be
paid (if any) by the 

  
 9. 













 
Participant for each share of Common Stock subject to a Restricted Stock Unit Award may be paid in any form of legal consideration that may be acceptable to the Board, in its sole discretion, and
permissible under applicable law. 
 (ii)        Vesting. At the time
of the grant of a Restricted Stock Unit Award, the Board may impose such restrictions on or conditions to the vesting of the Restricted Stock Unit Award as it, in its sole discretion, deems appropriate. 

(iii)        Payment. A Restricted Stock Unit Award may be settled by
the delivery of shares of Common Stock, their cash equivalent, any combination thereof or in any other form of consideration, as determined by the Board and contained in the Restricted Stock Unit Award Agreement. 

(iv)        Additional Restrictions. At the time of the grant of a
Restricted Stock Unit Award, the Board, as it deems appropriate, may impose such restrictions or conditions that delay the delivery of the shares of Common Stock (or their cash equivalent) subject to a Restricted Stock Unit Award to a time after the
vesting of such Restricted Stock Unit Award. 
 (v)        Dividend
Equivalents. Dividend equivalents may be credited in respect of shares of Common Stock covered by a Restricted Stock Unit Award, as determined by the Board and contained in the Restricted Stock Unit Award Agreement. At the sole discretion of the
Board, such dividend equivalents may be converted into additional shares of Common Stock covered by the Restricted Stock Unit Award in such manner as determined by the Board. Any additional shares covered by the Restricted Stock Unit Award credited
by reason of such dividend equivalents will be subject to all of the same terms and conditions of the underlying Restricted Stock Unit Award Agreement to which they relate. 

(vi)        Termination of Participant’s Continuous
Service. Except as otherwise provided in the applicable Restricted Stock Unit Award Agreement or other written agreement between a Participant and the Company or an Affiliate, such portion of the Restricted Stock Unit Award that has not vested
will be forfeited upon the Participant’s termination of Continuous Service. 

(c)          Performance Awards. 

(i)        Performance Stock Awards. A Performance Stock
Award is a Stock Award that is payable (including that may be granted, may vest or may be exercised) contingent upon the attainment during a Performance Period of certain Performance Goals. A Performance Stock Award may, but need not, require the
Participant’s completion of a specified period of Continuous Service. The length of any Performance Period, the Performance Goals to be achieved during the Performance Period, and the measure of whether and to what degree such Performance Goals
have been attained will be conclusively determined by the Board or Committee, in its sole discretion. In addition, to the extent permitted by applicable law and the applicable Award Agreement, the Board or the Committee may determine that cash may
be used in payment of Performance Stock Awards. 

(ii)        Performance Cash Awards. A Performance Cash Award is a cash
award that is payable contingent upon the attainment during a Performance Period of certain Performance Goals. A Performance Cash Award may also require the completion of a specified period of Continuous Service. At the time of grant of a
Performance Cash Award, the length of any Performance Period, the Performance Goals to be achieved during the Performance Period, and the measure of whether and to what degree such Performance Goals have been attained will be conclusively determined
by the Board or Committee, in its sole discretion. The Board or Committee may specify the form of payment of Performance Cash Awards, which may be cash or other property, or may provide for a Participant to have the option for his or her


  
 10. 













 
Performance Cash Award, or such portion thereof as the Board may specify, to be paid in whole or in part in cash or other property. 

(iii)        Board Discretion. The Board retains the discretion to
adjust or eliminate the compensation or economic benefit due upon attainment of Performance Goals and to define the manner of calculating the Performance Criteria it selects to use for a Performance Period. Partial achievement of the specified
criteria may result in the payment or vesting corresponding to the degree of achievement as specified in the Stock Award Agreement or the written terms of a Performance Cash Award. 

(d)        Other Stock Awards. Other forms of Stock Awards valued in
whole or in part by reference to, or otherwise based on, Common Stock, including the appreciation in value thereof (e.g., options or stock rights with an exercise price or strike price less than 100% of the Fair Market Value of the Common Stock at
the time of grant) may be granted either alone or in addition to Stock Awards provided for under Section 5 and the preceding provisions of this Section 6. Subject to the provisions of the Plan, the Board will have sole and complete
authority to determine the persons to whom and the time or times at which such Other Stock Awards will be granted, the number of shares of Common Stock (or the cash equivalent thereof) to be granted pursuant to such Other Stock Awards and all other
terms and conditions of such Other Stock Awards. 
  

	7.	 COVENANTS OF THE COMPANY.



 (a)        Availability of Shares. The
Company will keep available at all times the number of shares of Common Stock reasonably required to satisfy then-outstanding Stock Awards. 

(b)        Securities Law Compliance. The Company will seek to obtain
from each regulatory commission or agency having jurisdiction over the Plan, as necessary, such authority as may be required to grant Stock Awards and to issue and sell shares of Common Stock upon exercise or vesting of the Stock Awards;
provided, however, that this undertaking will not require the Company to register under the Securities Act or other securities or applicable laws, the Plan, any Stock Award or any Common Stock issued or issuable pursuant to any such Stock
Award. If, after reasonable efforts and at a reasonable cost, the Company is unable to obtain from any such regulatory commission or agency the authority that counsel for the Company deems necessary or advisable for the lawful issuance and sale of
Common Stock under the Plan, the Company will be relieved from any liability for failure to issue and sell Common Stock upon exercise or vesting of such Stock Awards unless and until such authority is obtained. A Participant will not be eligible for
the grant of an Award or the subsequent issuance of cash or Common Stock pursuant to the Award if such grant or issuance would be in violation of any applicable securities law. 

(c)        No Obligation to Notify or Minimize Taxes. The Company will
have no duty or obligation to any Participant to advise such holder as to the tax treatment or time or manner of exercising such Stock Award. Furthermore, the Company will have no duty or obligation to warn or otherwise advise such holder of a
pending termination or expiration of an Award or a possible period in which the Award may not be exercised. The Company has no duty or obligation to minimize the tax consequences of an Award to the holder of such Award. 

 

	8.	 MISCELLANEOUS. 



(a)        Use of Proceeds from Sales of Common Stock. Proceeds from the
sale of shares of Common Stock pursuant to Stock Awards will constitute general funds of the Company. 

(b)        Corporate Action Constituting Grant of Awards. Corporate
action constituting a grant by the Company of an Award to any Participant will be deemed completed as of the date of such corporate 

  
 11. 













 
action, unless otherwise determined by the Board, regardless of when the instrument, certificate, or letter evidencing the Award is communicated to, or actually received or accepted by, the
Participant. In the event that the corporate records (e.g., Board consents, resolutions or minutes) documenting the corporate action approving the grant contain terms (e.g., exercise price, vesting schedule or number of shares) that are inconsistent
with those in the Award Agreement or related grant documents as a result of a clerical error in the papering of the Award Agreement or related grant documents, the corporate records will control and the Participant will have no legally binding right
to the incorrect term in the Award Agreement or related grant documents. 

(c)        Stockholder Rights. No Participant will be deemed to be the
holder of, or to have any of the rights of a holder with respect to, any shares of Common Stock subject to an Award unless and until (i) such Participant has satisfied all requirements for exercise of, or the issuance of shares of Common Stock
under, the Award pursuant to its terms, and (ii) the issuance of the Common Stock subject to such Award has been entered into the books and records of the Company. 

(d)        No Employment or Other Service Rights. Nothing in the Plan,
any Award Agreement or any other instrument executed thereunder or in connection with any Award granted pursuant thereto will confer upon any Participant any right to continue to serve the Company or an Affiliate in the capacity in effect at the
time the Award was granted or will affect the right of the Company or an Affiliate to terminate (i) the employment of an Employee with or without notice and with or without cause, (ii) the service of a Consultant pursuant to the terms of
such Consultant’s agreement with the Company or an Affiliate, or (iii) the service of a Director pursuant to the bylaws of the Company or an Affiliate, and any applicable provisions of the corporate law of the state or foreign jurisdiction
in which the Company or the Affiliate is domiciled or incorporated, as the case may be. 

(e)        Change in Time Commitment. In the event a Participant’s
regular level of time commitment in the performance of his or her services for the Company and any Affiliates is reduced (for example, and without limitation, if the Participant is an Employee of the Company and the Employee has a change in status
from a full-time Employee to a part-time Employee or takes an extended leave of absence) after the date of grant of any Award to the Participant, the Board has the right in its sole discretion to (x) prospectively make a corresponding reduction
in the number of shares or cash amount subject to any portion of such Award that is scheduled to vest or become payable after the date of such change in time commitment, provided that the Board gives prior notice to the Employee of the reduction and
that in the absence of such notice, no reduction shall occur, and (y) in lieu of or in combination with such a reduction, extend the vesting or payment schedule applicable to such Award. In the event of any such reduction, the Participant will
have no right with respect to any portion of the Award that is so reduced or extended. 

(f)        Incentive Stock Option Limitations. To the extent that the
aggregate Fair Market Value (determined at the time of grant) of Common Stock with respect to which Incentive Stock Options are exercisable for the first time by any Optionholder during any calendar year (under all plans of the Company and any
Affiliates) exceeds $100,000 (or such other limit established in the Code) or otherwise does not comply with the rules governing Incentive Stock Options, the Options or portions thereof that exceed such limit (according to the order in which they
were granted) or otherwise do not comply with such rules will be treated as Nonstatutory Stock Options, notwithstanding any contrary provision of the applicable Option Agreement(s). 

(g)        Investment Assurances. The Company may require a Participant,
as a condition of exercising or acquiring Common Stock under any Award, (i) to give written assurances satisfactory to the Company as to the Participant’s knowledge and experience in financial and business matters and/or to employ a
purchaser representative reasonably satisfactory to the Company who is knowledgeable and experienced in financial and business matters and that such Participant is capable of evaluating, alone or 

  
 12. 













 
together with the purchaser representative, the merits and risks of exercising the Award; and (ii) to give written assurances satisfactory to the Company stating that the Participant is
acquiring Common Stock subject to the Award for the Participant’s own account and not with any present intention of selling or otherwise distributing the Common Stock. The foregoing requirements, and any assurances given pursuant to such
requirements, will be inoperative if (A) the issuance of the shares upon the exercise or acquisition of Common Stock under the Stock Award has been registered under a then currently effective registration statement under the Securities Act, or
(B) as to any particular requirement, a determination is made by counsel for the Company that such requirement need not be met in the circumstances under the then applicable securities laws. The Company may, upon advice of counsel to the
Company, place legends on stock certificates issued under the Plan as such counsel deems necessary or appropriate in order to comply with applicable securities laws, including, but not limited to, legends restricting the transfer of the Common
Stock. 
 (h)        Withholding Obligations. Unless prohibited by the
terms of an Award Agreement, the Company may, in its sole discretion, satisfy any federal, state or local tax withholding obligation relating to an Award by any of the following means or by a combination of such means: (i) causing the
Participant to tender a cash payment; (ii) withholding shares of Common Stock from the shares of Common Stock issued or otherwise issuable to the Participant in connection with the Stock Award; provided, however, that no shares of Common
Stock are withheld with a value exceeding the maximum amount of tax required to be withheld by law (or such lesser amount as may be necessary to avoid classification of the Stock Award as a liability for financial accounting purposes); (iii)
withholding cash from an Award settled in cash; (iv) withholding payment from any amounts otherwise payable to the Participant; or (v) by such other method as may be set forth in the Award Agreement. 

(i)        Electronic Delivery. Any reference herein to a
“written” agreement or document will include any agreement or document delivered electronically, filed publicly at www.sec.gov (or any successor website thereto) or posted on the Company’s intranet (or other shared electronic medium
controlled by the Company to which the Participant has access). 

(j)        Deferrals. To the extent permitted by applicable law, the
Board, in its sole discretion, may determine that the delivery of Common Stock or the payment of cash, upon the exercise, vesting or settlement of all or a portion of any Award may be deferred and may establish programs and procedures for deferral
elections to be made by Participants. Deferrals by Participants will be made in accordance with Section 409A of the Code. Consistent with Section 409A of the Code, the Board may provide for distributions while a Participant is still an
employee or otherwise providing services to the Company. The Board is authorized to make deferrals of Awards and determine when, and in what annual percentages, Participants may receive payments, including lump sum payments, following the
Participant’s termination of Continuous Service, and implement such other terms and conditions consistent with the provisions of the Plan and in accordance with applicable law. 

(k)        Clawback/Recovery. All Awards granted under the Plan will be
subject to recoupment in accordance with any clawback policy that the Company is required to adopt pursuant to the listing standards of any national securities exchange or association on which the Company’s securities are listed or as is
otherwise required by the Dodd-Frank Wall Street Reform and Consumer Protection Act or other applicable law. In addition, the Board may impose such other clawback, recovery or recoupment provisions in an Award Agreement as the Board determines
necessary or appropriate, including but not limited to a reacquisition right in respect of previously acquired shares of Common Stock or other cash or property upon the occurrence of an event constituting Cause. No recovery of compensation under
such a clawback policy will be an event giving rise to a right to voluntary terminate employment upon a “resignation for good reason,” or for a “constructive termination” or any similar term under any plan of or agreement with
the Company. 

  
 13. 













 (l)        Compliance with
Section 409A of the Code. Unless otherwise expressly provided for in an Award Agreement, the Plan and Award Agreements will be interpreted to the greatest extent possible in a manner that makes the Plan and the Awards granted
hereunder exempt from Section 409A of the Code, and, to the extent not so exempt, in compliance with Section 409A of the Code. If the Board determines that any Award granted hereunder is not exempt from and is therefore subject to
Section 409A of the Code, the Award Agreement evidencing such Award will incorporate the terms and conditions necessary to avoid the consequences specified in Section 409A(a)(1) of the Code, and to the extent an Award Agreement is silent
on terms necessary for compliance, such terms are hereby incorporated by reference into the Award Agreement. Notwithstanding anything to the contrary in this Plan (and unless the Award Agreement specifically provides otherwise), if the shares of
Common Stock are publicly traded, and if a Participant holding an Award that constitutes “deferred compensation” under Section 409A of the Code is a “specified employee” for purposes of Section 409A of the Code, no
distribution or payment of any amount that is due because of a “separation from service” (as defined in Section 409A of the Code without regard to alternative definitions thereunder) will be issued or paid before the date that is six
months following the date of such Participant’s “separation from service” or, if earlier, the date of the Participant’s death, unless such distribution or payment can be made in a manner that complies with Section 409A of
the Code, and any amounts so deferred will be paid in a lump sum on the day after such six month period elapses, with the balance paid thereafter on the original schedule. 
  

	9.	 ADJUSTMENTS UPON CHANGES IN
COMMON STOCK; OTHER CORPORATE EVENTS. 



(a)        Capitalization Adjustments. In the event of a Capitalization
Adjustment, the Board will appropriately and proportionately adjust: (i) the class(es) and maximum number of securities subject to the Plan pursuant to Section 3(a), (ii) the class(es) and maximum number of securities by which the share
reserve is to increase automatically each year pursuant to Section 3(a), (iii) the class(es) and maximum number of securities that may be issued pursuant to the exercise of Incentive Stock Options pursuant to Section 3(c), and
(iv) the class(es) and number of securities and price per share of stock subject to outstanding Stock Awards. The Board will make such adjustments, and its determination will be final, binding and conclusive. 

(b)        Dissolution. Except as otherwise provided in the Stock Award
Agreement, in the event of a Dissolution of the Company, all outstanding Stock Awards (other than Stock Awards consisting of vested and outstanding shares of Common Stock not subject to a forfeiture condition or the Company’s right of
repurchase) will terminate immediately prior to the completion of such Dissolution, and the shares of Common Stock subject to the Company’s repurchase rights or subject to a forfeiture condition may be repurchased or reacquired by the Company
notwithstanding the fact that the holder of such Stock Award is providing Continuous Service; provided, however, that the Board may, in its sole discretion, cause some or all Stock Awards to become fully vested, exercisable and/or no longer
subject to repurchase or forfeiture (to the extent such Stock Awards have not previously expired or terminated) before the Dissolution is completed but contingent on its completion. 

(c)        Transaction. The following provisions will apply to Stock
Awards in the event of a Transaction unless otherwise provided in the instrument evidencing the Stock Award or any other written agreement between the Company or any Affiliate and the Participant or unless otherwise expressly provided by the Board
at the time of grant of a Stock Award. In the event of a Transaction, then, notwithstanding any other provision of the Plan, the Board may take one or more of the following actions with respect to Stock Awards, contingent upon the closing or
completion of the Transaction: 
 (i)        arrange for the surviving
corporation or acquiring corporation (or the surviving or acquiring corporation’s parent company) to assume or continue the Stock Award or to substitute a similar 

  
 14. 













 
stock award for the Stock Award (including, but not limited to, an award to acquire the same consideration paid to the stockholders of the Company pursuant to the Transaction); 

(ii)        arrange for the assignment of any reacquisition or repurchase
rights held by the Company in respect of Common Stock issued pursuant to the Stock Award to the surviving corporation or acquiring corporation (or the surviving or acquiring corporation’s parent company); 

(iii)        accelerate the vesting, in whole or in part, of the Stock Award
(and, if applicable, the time at which the Stock Award may be exercised) to a date prior to the effective time of such Transaction as the Board determines (or, if the Board does not determine such a date, to the date that is five days prior to the
effective date of the Transaction), with such Stock Award terminating if not exercised (if applicable) at or prior to the effective time of the Transaction; provided, however, that the Board may require Participants to complete and deliver to
the Company a notice of exercise before the effective date of a Transaction, which exercise is contingent upon the effectiveness of such Transaction; 

(iv)        arrange for the lapse, in whole or in part, of any reacquisition
or repurchase rights held by the Company with respect to the Stock Award; 

(v)        cancel or arrange for the cancellation of the Stock Award, to the
extent not vested or not exercised prior to the effective time of the Transaction, in exchange for such cash consideration, if any, as the Board, in its sole discretion, may consider appropriate; and 

(vi)        make a payment, in such form as may be determined by the Board
equal to the excess, if any, of (A) the value of the property the Participant would have received upon the exercise of the Stock Award immediately prior to the effective time of the Transaction, over (B) any exercise price payable by such
holder in connection with such exercise. For clarity, this payment may be $0 if the value of the property is equal to or less than the exercise price. Payments under this provision may be delayed to the same extent that payment of consideration to
the holders of the Company’s Common Stock in connection with the Transaction is delayed as a result of escrows, earn outs, holdbacks or any other contingencies. 

The Board need not take the same action or actions with respect to all Stock Awards or portions thereof or with respect to all
Participants. The Board may take different actions with respect to the vested and unvested portions of a Stock Award. 

(d)        Change in Control. A Stock Award may be subject to additional
acceleration of vesting and exercisability upon or after a Change in Control as may be provided in the Stock Award Agreement for such Stock Award or as may be provided in any other written agreement between the Company or any Affiliate and the
Participant, but in the absence of such provision, no such acceleration will automatically occur. 
  

	10.	 PLAN TERM; EARLIER TERMINATION
OR SUSPENSION OF THE PLAN. 



The Board may suspend or terminate the Plan at any time. No Incentive Stock Options may be granted after the tenth anniversary
of the earlier of (i) the date the Plan is adopted by the Board (the “Adoption Date”), or (ii) the date the Plan is approved by the stockholders of the Company. No Awards may be granted under the Plan while the Plan
is suspended or after it is terminated. 
  

	11.	 EXISTENCE OF THE PLAN; TIMING
OF FIRST GRANT OR EXERCISE. 



The Plan will come into existence on the Adoption Date; provided, however, that no Stock Award may be granted prior to
the IPO Date. In addition, no Stock Award will be exercised (or, in the case of a 

  
 15. 













 
Restricted Stock Award, Restricted Stock Unit Award, Performance Share Award, or Other Stock Award, no Stock Award will be granted) and no Performance Cash Award will be settled unless and until
the Plan has been approved by the stockholders of the Company, which approval will be within 12 months after the date the Plan is adopted by the Board. 
  

	12.	 CHOICE OF LAW. 



The laws of the State of Delaware will govern all questions concerning the construction, validity and interpretation of this
Plan, without regard to that state’s conflict of laws rules. 
  

	13.	 DEFINITIONS. As used in the Plan, the following definitions will apply to the
capitalized terms indicated below: 



(a)        “Affiliate” means, at the time of
determination, any “parent” or “subsidiary” of the Company as such terms are defined in Rule 405 of the Securities Act. The Board will have the authority to determine the time or times at which “parent” or
“subsidiary” status is determined within the foregoing definition. 

(b)        “Award” means a Stock Award or a Performance
Cash Award. 
 (c)        “Award Agreement” means a
written agreement between the Company and a Participant evidencing the terms and conditions of an Award. 

(d)        “Board” means the Board of Directors of the
Company. 
 (e)        “Capital Stock” means each and
every class of common stock of the Company, regardless of the number of votes per share. 

(f)        “Capitalization Adjustment” means any change
that is made in, or other events that occur with respect to, the Common Stock subject to the Plan or subject to any Stock Award after the Adoption Date without the receipt of consideration by the Company through merger, consolidation,
reorganization, recapitalization, reincorporation, stock dividend, dividend in property other than cash, large nonrecurring cash dividend, stock split, reverse stock split, liquidating dividend, combination of shares, exchange of shares, change in
corporate structure or any similar equity restructuring transaction, as that term is used in Statement of Financial Accounting Standards Board Accounting Standards Codification Topic 718 (or any successor thereto). Notwithstanding the foregoing, the
conversion of any convertible securities of the Company will not be treated as a Capitalization Adjustment. 

(g)        “Cause” shall have the meaning
ascribed to such term in any written agreement between the Participant and the Company defining such term and, in the absence of such agreement, such term means, with respect to a Participant, the occurrence of any of the following events:
(i) such Participant’s commission of any felony or any crime involving fraud, dishonesty or moral turpitude under the laws of the United States or any state thereof; (ii) such Participant’s attempted commission of, or
participation in, a fraud or act of dishonesty against the Company; (iii) such Participant’s intentional, material violation of any contract or agreement between the Participant and the Company or of any statutory duty owed to the Company;
(iv) such Participant’s unauthorized use or disclosure of the Company’s confidential information or trade secrets; or (v) such Participant’s gross misconduct. The determination that a termination of the Participant’s
Continuous Service is either for Cause or without Cause shall be made by the Company, in its sole discretion. Any determination by the Company that the Continuous Service of a Participant was terminated with or without Cause for the purposes of
outstanding Awards held by such Participant shall 

  
 16. 













 
have no effect upon any determination of the rights or obligations of the Company or such Participant for any other purpose. 

(h)        “Change in Control” means the occurrence, in
a single transaction or in a series of related transactions, of any one or more of the following events:  

(i)        any Exchange Act Person becomes the Owner, directly or indirectly,
of securities of the Company representing more than 50% of the combined voting power of the Company’s then outstanding securities other than by virtue of a merger, consolidation or similar transaction. Notwithstanding the foregoing, a Change in
Control will not be deemed to occur (A) on account of the acquisition of securities of the Company directly from the Company, (B) on account of the acquisition of securities of the Company by an investor, any affiliate thereof or any other
Exchange Act Person that acquires the Company’s securities in a transaction or series of related transactions the primary purpose of which is to obtain financing for the Company through the issuance of equity securities, (C) on account of
the acquisition of securities of the Company by any individual who is, on the IPO Date, either an executive officer or a Director (either, an “IPO Investor”) and/or any entity in which an IPO Investor has a direct or indirect
interest (whether in the form of voting rights or participation in profits or capital contributions) of more than 50% (collectively, the “IPO Entities”) or on account of the IPO Entities continuing to hold shares that come to
represent more than 50% of the combined voting power of the Company’s then outstanding securities as a result of the conversion of any class of the Company’s securities into another class of the Company’s securities having a different
number of votes per share pursuant to the conversion provisions set forth in the Company’s Amended and Restated Certificate of Incorporation; or (D) solely because the level of Ownership held by any Exchange Act Person (the
“Subject Person”) exceeds the designated percentage threshold of the outstanding voting securities as a result of a repurchase or other acquisition of voting securities by the Company reducing the number of shares
outstanding, provided that if a Change in Control would occur (but for the operation of this sentence) as a result of the acquisition of voting securities by the Company, and after such share acquisition, the Subject Person becomes the Owner of any
additional voting securities that, assuming the repurchase or other acquisition had not occurred, increases the percentage of the then outstanding voting securities Owned by the Subject Person over the designated percentage threshold, then a Change
in Control will be deemed to occur; 
 (ii)        there is consummated a
merger, consolidation or similar transaction involving (directly or indirectly) the Company and, immediately after the consummation of such merger, consolidation or similar transaction, the stockholders of the Company immediately prior thereto do
not Own, directly or indirectly, either (A) outstanding voting securities representing more than 50% of the combined outstanding voting power of the surviving Entity in such merger, consolidation or similar transaction or (B) more than 50%
of the combined outstanding voting power of the parent of the surviving Entity in such merger, consolidation or similar transaction, in each case in substantially the same proportions as their Ownership of the outstanding voting securities of the
Company immediately prior to such transaction; provided, however, that a merger, consolidation or similar transaction will not constitute a Change in Control under this prong of the definition if the outstanding voting securities representing
more than 50% of the combined voting power of the surviving Entity or its parent are owned by the IPO Entities; 

(iii)        there is consummated a sale, lease, exclusive license or other
disposition of all or substantially all of the consolidated assets of the Company and its Subsidiaries, other than a sale, lease, license or other disposition of all or substantially all of the consolidated assets of the Company and its Subsidiaries
to an Entity, more than 50% of the combined voting power of the voting securities of which are Owned by stockholders of the Company in substantially the same proportions as their Ownership of the outstanding voting securities of the Company
immediately prior to such sale, lease, license or other disposition; provided, however, that a sale, lease, exclusive license or other disposition of all or substantially all of the consolidated assets of the Company and its Subsidiaries will
not constitute a Change in Control 

  
 17. 













 
under this prong of the definition if the outstanding voting securities representing more than 50% of the combined voting power of the acquiring Entity or its parent are owned by the IPO
Entities; 
 (iv)        the stockholders of the Company approve or the
Board approves a plan of complete dissolution or liquidation of the Company, or a complete dissolution or liquidation of the Company will otherwise occur, except for a liquidation into a parent corporation; or 

(v)        individuals who, on the IPO Date, are members of the Board (the
“Incumbent Board”) cease for any reason to constitute at least a majority of the members of the Board; provided, however, that if the appointment or election (or nomination for
election) of any new Board member was approved or recommended by a majority vote of the members of the Incumbent Board then still in office, such new member will, for purposes of this Plan, be considered as a member of the Incumbent Board. 

Notwithstanding the foregoing definition or any other provision of the Plan, (A) the term Change in Control will not
include a sale of assets, merger or other transaction effected exclusively for the purpose of changing the domicile of the Company and (B) the definition of Change in Control (or any analogous term) in an individual written agreement between
the Company or any Affiliate and the Participant will supersede the foregoing definition with respect to Awards subject to such agreement; provided, however, that if no definition of Change in Control or any analogous term is set forth in
such an individual written agreement, the foregoing definition will apply. 

(i)        “Code” means the Internal Revenue Code of
1986, as amended, including any applicable regulations and guidance thereunder. 

(j)        “Committee” means a committee of one or more
Directors to whom authority has been delegated by the Board in accordance with Section 2(c). 

(k)        “Common Stock” means, as of the IPO Date,
the common stock of the Company, having one vote per share. 

(l)        “Company” means Synthorx, Inc., a Delaware
corporation. 
 (m)        “Consultant” means any
person, including an advisor, who is (i) engaged by the Company or an Affiliate to render consulting or advisory services and is compensated for such services, or (ii) serving as a member of the board of directors of an Affiliate and is
compensated for such services. However, service solely as a Director, or payment of a fee for such service, will not cause a Director to be considered a “Consultant” for purposes of the Plan. Notwithstanding the foregoing, a
person is treated as a Consultant under this Plan only if a Form S-8 Registration Statement under the Securities Act is available to register either the offer or the sale of the Company’s securities to
such person. 
 (n)        “Continuous Service” means
that the Participant’s service with the Company or an Affiliate, whether as an Employee, Director or Consultant, is not interrupted or terminated. A change in the capacity in which the Participant renders service to the Company or an Affiliate
as an Employee, Consultant or Director or a change in the entity for which the Participant renders such service, provided that there is no interruption or termination of the Participant’s service with the Company or an Affiliate, will not
terminate a Participant’s Continuous Service; provided, however, that if the Entity for which a Participant is rendering services ceases to qualify as an Affiliate, as determined by the Board, in its sole discretion, such
Participant’s Continuous Service will be considered to have terminated on the date such Entity ceases to qualify as an Affiliate. To the extent permitted by law, the Board or the chief executive officer of the Company, in that party’s sole
discretion, may determine whether Continuous Service will be 

  
 18. 













 
considered interrupted in the case of (i) any leave of absence approved by the Board or chief executive officer, including sick leave, military leave or any other personal leave, or
(ii) transfers between the Company, an Affiliate, or their successors. Notwithstanding the foregoing, a leave of absence will be treated as Continuous Service for purposes of vesting in an Award only to such extent as may be provided in the
Company’s leave of absence policy, in the written terms of any leave of absence agreement or policy applicable to the Participant, or as otherwise required by law. 

(o)        “Corporate Transaction” means the
consummation, in a single transaction or in a series of related transactions, of any one or more of the following events: 

(i)        a sale or other disposition of all or substantially all, as
determined by the Board, in its sole discretion, of the consolidated assets of the Company and its Subsidiaries; 

(ii)        a sale or other disposition of more than 50% of the outstanding
securities of the Company; 
 (iii)        a merger, consolidation or
similar transaction following which the Company is not the surviving corporation; or 

(iv)        a merger, consolidation or similar transaction following which the
Company is the surviving corporation but the shares of Common Stock outstanding immediately preceding the merger, consolidation or similar transaction are converted or exchanged by virtue of the merger, consolidation or similar transaction into
other property, whether in the form of securities, cash or otherwise. 

(p)        “Director” means a member of the Board. 

(q)        “Disability” means, with respect to a
Participant, the inability of such Participant to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment that can be expected to result in death or that has lasted or can be expected to last
for a continuous period of not less than 12 months, as provided in Sections 22(e)(3) and 409A(a)(2)(c)(i) of the Code, and will be determined by the Board on the basis of such medical evidence as the Board deems warranted under the circumstances.

 (r)        “Dissolution” means when the Company,
after having executed a certificate of dissolution with the State of Delaware (or other applicable state), has completely wound up its affairs. Conversion of the Company into a Limited Liability Company (or any other pass-through entity) will not be
considered a “Dissolution” for purposes of the Plan. 
 (s)        
“Employee” means any person employed by the Company or an Affiliate. However, service solely as a Director, or payment of a fee for such services, will not cause a Director to be considered an “Employee” for
purposes of the Plan. 
 (t)        “Entity” means a
corporation, partnership, limited liability company or other entity. 

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

(v)        “Exchange Act Person” means
any natural person, Entity or “group” (within the meaning of Section 13(d) or 14(d) of the Exchange Act), except that “Exchange Act Person” will not include (i) the Company or any Subsidiary of the Company,
(ii) any employee benefit plan of the Company or any Subsidiary of the Company or any trustee or other fiduciary holding securities under an employee benefit 

  
 19. 













 
plan of the Company or any Subsidiary of the Company, (iii) an underwriter temporarily holding securities pursuant to a registered public offering of such securities, (iv) an Entity
Owned, directly or indirectly, by the stockholders of the Company in substantially the same proportions as their Ownership of stock of the Company; or (v) any natural person, Entity or “group” (within the meaning of Section 13(d)
or 14(d) of the Exchange Act) that, as of the IPO Date, is the Owner, directly or indirectly, of securities of the Company representing more than 50% of the combined voting power of the Company’s then outstanding securities. 

(w)        “Fair Market Value” means, as of any date,
the value of the Common Stock determined as follows: 
 (i)        If the
Common Stock is listed on any established stock exchange or traded on any established market, the Fair Market Value of a share of Common Stock will be, unless otherwise determined by the Board, the closing sales price for such stock as quoted on
such exchange or market (or the exchange or market with the greatest volume of trading in the Common Stock) on the date of determination, as reported in a source the Board deems reliable. 

(ii)        Unless otherwise provided by the Board, if there is no closing
sales price for the Common Stock on the date of determination, then the Fair Market Value will be the closing selling price on the last preceding date for which such quotation exists. 

(iii)        In the absence of such markets for the Common Stock, the Fair
Market Value will be determined by the Board in good faith and in a manner that complies with Sections 409A and 422 of the Code. 

(x)        “Incentive Stock Option” means an option
granted pursuant to Section 5 of the Plan that is intended to be, and qualifies as, an “incentive stock option” within the meaning of Section 422 of the Code. 

(y)        “IPO Date” means the date of the
underwriting agreement between the Company and the underwriter(s) managing the initial public offering of the Common Stock, pursuant to which the Common Stock is priced for the initial public offering. 

(z)        “Non-Employee
Director” means a Director who either (i) is not a current employee or officer of the Company or an Affiliate, does not receive compensation, either directly or indirectly, from the Company or an Affiliate for services
rendered as a consultant or in any capacity other than as a Director (except for an amount as to which disclosure would not be required under Item 404(a) of Regulation S-K promulgated pursuant to the
Securities Act (“Regulation S-K”)), does not possess an interest in any other transaction for which disclosure would be required under Item 404(a) of Regulation S-K, and is not engaged in a business relationship for which disclosure would be required pursuant to Item 404(b) of Regulation S-K; or (ii) is otherwise considered
a “non-employee director” for purposes of Rule 16b-3. 

(aa)        “Nonstatutory Stock Option” means any
Option granted pursuant to Section 5 of the Plan that does not qualify as an Incentive Stock Option. 

(bb)        “Officer” means a person who is an officer
of the Company within the meaning of Section 16 of the Exchange Act. 

(cc)        “Option” means an Incentive Stock Option or
a Nonstatutory Stock Option to purchase shares of Common Stock granted pursuant to the Plan. 

  
 20. 














(dd)        “Option Agreement” means a written agreement
between the Company and an Optionholder evidencing the terms and conditions of an Option grant. Each Option Agreement will be subject to the terms and conditions of the Plan. 

(ee)        “Optionholder” means a person to whom an
Option is granted pursuant to the Plan or, if applicable, such other person who holds an outstanding Option. 

(ff)        “Other Stock Award” means an award based in
whole or in part by reference to the Common Stock which is granted pursuant to the terms and conditions of Section 6(d). 

(gg)        “Other Stock Award Agreement”
means a written agreement between the Company and a holder of an Other Stock Award evidencing the terms and conditions of an Other Stock Award grant. Each Other Stock Award Agreement will be subject to the terms and conditions of the Plan.

 (hh)        “Own,”
“Owned,” “Owner,” “Ownership” means a person or Entity will be deemed to “Own,” to have “Owned,” to be the
“Owner” of, or to have acquired “Ownership” of securities if such person or Entity, directly or indirectly, through any contract, arrangement, understanding, relationship or otherwise, has or shares voting power, which includes
the power to vote or to direct the voting, with respect to such securities. 

(ii)        “Participant” means a person to whom an
Award is granted pursuant to the Plan or, if applicable, such other person who holds an outstanding Stock Award. 

(jj)        “Performance Cash Award” means an award of
cash granted pursuant to the terms and conditions of Section 6(c)(ii). 

(kk)        “Performance Criteria” means the one or
more criteria that the Board will select for purposes of establishing the Performance Goals for a Performance Period. The Performance Criteria that will be used to establish such Performance Goals may be based on any one of, or combination of,
the following as determined by the Board: (i) sales; (ii) revenues; (iii) assets; (iv) expenses; (v) market penetration or expansion; (vi) earnings from operations; (vii) earnings before or after deduction for all or any
portion of interest, taxes, depreciation, amortization, incentives, service fees or extraordinary or special items, whether or not on a continuing operations or an aggregate or per share basis; (viii) net income or net income per common share
(basic or diluted); (ix) return on equity, investment, capital or assets; (x) one or more operating ratios; (xi) borrowing levels, leverage ratios or credit rating; (xii) market share; (xiii) capital expenditures; (xiv) cash
flow, free cash flow, cash flow return on investment, or net cash provided by operations; (xv) stock price, dividends or total stockholder return; (xvi) development of new technologies or products; (xvii) sales of particular products
or services; (xviii) economic value created or added; (xix) operating margin or profit margin; (xx) customer acquisition or retention; (xxi) raising or refinancing of capital; (xxii) successful hiring of key individuals;
(xxiii) resolution of significant litigation; (xxiv) acquisitions and divestitures (in whole or in part); (xxv) joint ventures and strategic alliances; (xxvi) spin-offs, split-ups and the like;
(xxvii) reorganizations; (xxviii) recapitalizations, restructurings, financings (issuance of debt or equity) or refinancings; (xxix) or strategic business criteria, consisting of one or more objectives based on the following goals:
achievement of timely development, design management or enrollment, meeting specified market penetration or value added, payor acceptance, patient adherence, peer reviewed publications, issuance of new patents, establishment of or securing of
licenses to intellectual property, product development or introduction (including, without limitation, any clinical trial accomplishments, regulatory or other filings, approvals or milestones, discovery of novel products, maintenance of multiple
products in pipeline, product launch or other product development milestones), geographic business expansion, cost targets, cost reductions or savings, customer satisfaction, operating efficiency, acquisition or retention, employee satisfaction,
information technology, corporate development 

  
 21. 













 
(including, without limitation, licenses, innovation, research or establishment of third party collaborations), manufacturing or process development, legal compliance or risk reduction, patent
application or issuance goals, or goals relating to acquisitions, divestitures or other business combinations (in whole or in part), joint ventures or strategic alliances; and (xxx) other measures of performance selected by the Board. 

(ll)        “Performance Goals” means, for a
Performance Period, the one or more goals established by the Board for the Performance Period based upon the Performance Criteria. Performance Goals may be based on a Company-wide basis, with respect to one or more business units, divisions,
Affiliates, or business segments, and in either absolute terms or relative to the performance of one or more comparable companies or the performance of one or more relevant indices. The Board is authorized at any time in its sole discretion, to
adjust or modify the calculation of a Performance Goal for such Performance Period in order to prevent the dilution or enlargement of the rights of Participants, (a) in the event of, or in anticipation of, any unusual or extraordinary corporate
item, transaction, event or development; (b) in recognition of, or in anticipation of, any other unusual or nonrecurring events affecting the Company, or the financial statements of the Company in response to, or in anticipation of, changes in
applicable laws, regulations, accounting principles, or business conditions; or (c) in view of the Board’s assessment of the business strategy of the Company, performance of comparable organizations, economic and business conditions, and
any other circumstances deemed relevant. Specifically, the Board is authorized to make adjustment in the method of calculating attainment of Performance Goals and objectives for a Performance Period as follows: (i) to exclude the dilutive
effects of acquisitions or joint ventures; (ii) to assume that any business divested by the Company achieved performance objectives at targeted levels during the balance of a Performance Period following such divestiture; and (iii) to
exclude the effect of any change in the outstanding shares of common stock of the Company by reason of any stock dividend or split, stock repurchase, reorganization, recapitalization, merger, consolidation,
spin-off, combination or exchange of shares or other similar corporate change, or any distributions to common stockholders other than regular cash dividends. In addition, the Board is authorized to make
adjustment in the method of calculating attainment of Performance Goals and objectives for a Performance Period as follows: (i) to exclude restructuring and/or other nonrecurring charges; (ii) to exclude exchange rate effects, as
applicable, for non-U.S. dollar denominated net sales and operating earnings; (iii) to exclude the effects of changes to generally accepted accounting standards required by the Financial Accounting
Standards Board; (iv) to exclude the effects of any items that are “unusual” in nature or occur “infrequently” as determined under generally accepted accounting principles; (v) to exclude the effects to any statutory
adjustments to corporate tax rates; and (vi) to make other appropriate adjustments selected by the Board. 

(mm)        “Performance Period” means the period of
time selected by the Board over which the attainment of one or more Performance Goals will be measured for the purpose of determining a Participant’s right to and the payment of a Stock Award or a Performance Cash Award. Performance Periods may
be of varying and overlapping duration, at the sole discretion of the Board. 

(nn)        “Performance Stock Award” means a Stock
Award granted under the terms and conditions of Section 6(c)(i). 

(oo)        “Plan” means this Synthorx, Inc. 2018
Equity Incentive Plan. 
 (pp)        “Restricted Stock
Award” means an award of shares of Common Stock, which is granted pursuant to the terms and conditions of Section 6(a). 

(qq)        “Restricted Stock Award Agreement” means a
written agreement between the Company and a holder of a Restricted Stock Award evidencing the terms and conditions of a Restricted Stock Award grant. Each Restricted Stock Award Agreement will be subject to the terms and conditions of the Plan. 


  
 22. 














(rr)        “Restricted Stock Unit Award”
means a right to receive shares of Common Stock which is granted pursuant to the terms and conditions of Section 6(b). 

(ss)        “Restricted Stock Unit Award
Agreement” means a written agreement between the Company and a holder of a Restricted Stock Unit Award evidencing the terms and conditions of a Restricted Stock Unit Award grant. Each Restricted Stock Unit Award Agreement
will be subject to the terms and conditions of the Plan. 

(tt)        “Rule
16b-3” means Rule 16b-3 promulgated under the Exchange Act or any successor to Rule 16b-3, as in effect from time to
time. 
 (uu)        “Securities Act” means the
Securities Act of 1933, as amended. 
 (vv)        “Stock
Appreciation Right” or “SAR” means a right to receive the appreciation on Common Stock that is granted pursuant to the terms and conditions of Section 5. 

(ww)        “Stock Appreciation Right Agreement” means
a written agreement between the Company and a holder of a Stock Appreciation Right evidencing the terms and conditions of a Stock Appreciation Right grant. Each Stock Appreciation Right Agreement will be subject to the terms and conditions of the
Plan. 
 (xx)        “Stock Award” means any right to
receive Common Stock granted under the Plan, including an Incentive Stock Option, a Nonstatutory Stock Option, a Restricted Stock Award, a Restricted Stock Unit Award, a Stock Appreciation Right, a Performance Stock Award or any Other Stock Award.

 (yy)        “Stock Award Agreement”
means a written agreement between the Company and a Participant evidencing the terms and conditions of a Stock Award grant. Each Stock Award Agreement will be subject to the terms and conditions of the Plan. 

(zz)        “Subsidiary” means, with respect to the
Company, (i) any corporation of which more than 50% of the outstanding capital stock having ordinary voting power to elect a majority of the board of directors of such corporation (irrespective of whether, at the time, stock of any other class
or classes of such corporation will have or might have voting power by reason of the happening of any contingency) is at the time, directly or indirectly, Owned by the Company, and (ii) any partnership, limited liability company or other entity
in which the Company has a direct or indirect interest (whether in the form of voting or participation in profits or capital contribution) of more than 50%. 

(aaa)        “Ten Percent Stockholder” means a person
who Owns (or is deemed to Own pursuant to Section 424(d) of the Code) stock possessing more than 10% of the total combined voting power of all classes of stock of the Company or any Affiliate. 

(bbb)        “Transaction” means a Corporate
Transaction or a Change in Control. 

  
 23. 













 Standard Form 

SYNTHORX, INC. 

STOCK OPTION GRANT NOTICE 

(2018 EQUITY INCENTIVE PLAN) 

Synthorx, Inc. (the “Company”), pursuant to its 2018 Equity Incentive Plan (the
“Plan”), hereby grants to Optionholder an option to purchase the number of shares of the Company’s Common Stock set forth below. This option is subject to all of the terms and conditions as set forth in this Stock Option
Grant Notice, in the Option Agreement, the Plan and the Notice of Exercise, all of which are attached hereto and incorporated herein in their entirety. Capitalized terms not explicitly defined herein but defined in the Plan or the Option Agreement
will have the same definitions as in the Plan or the Option Agreement. If there is any conflict between the terms in this Stock Option Grant Notice and the Plan, the terms of the Plan will control. 

 

					
	 Optionholder:
	  	  
	  	
	 Date of Grant:
	  	  
	  	
	 Vesting Commencement Date:
	  	  
	  	
	 Number of Shares Subject to Option:
	  	  
	  	
	 Exercise Price (Per Share):
	  	  
	  	
	 Total Exercise Price:
	  	  
	  	
	 Expiration Date:
	  	  
	  	

  

			
	 Type of Grant:
	  	 ☐ Incentive Stock Option1
                        ☐ Nonstatutory Stock Option

		
	 Exercise Schedule:
	  	 Same as Vesting Schedule

		
	 Vesting Schedule:
	  	 [One-fourth (1/4th) of
the shares vest one (1) year after the Vesting Commencement Date, and the balance of the shares vest in a series of thirty-six (36) successive equal monthly installments measured from the first
anniversary of the Vesting Commencement Date], subject to Optionholder’s Continuous Service as of each such date and the potential vesting acceleration described in Section 1 of the Option Agreement.

		
	 Payment:
	  	 By one or a combination of the following items (described in the Option Agreement):

		
		  	 ☒    By cash, check, bank draft or money order payable to the Company

☒    Pursuant to a Regulation T Program if the shares are publicly traded

☐    By delivery of already-owned shares if the shares are publicly traded

☐    If and only to the extent this option is a Nonstatutory Stock Option, and subject to the Company’s consent
at the time of exercise, by a “net exercise” arrangement


  
  

1 If this is an Incentive Stock Option, it (plus other outstanding Incentive Stock Options) cannot be first
exercisable for more than $100,000 in value (measured by exercise price) in any calendar year. Any excess over $100,000 is a Nonstatutory Stock Option. 

  
 1. 













 Additional Terms/Acknowledgements: Optionholder acknowledges receipt of, and
understands and agrees to, this Stock Option Grant Notice, the Option Agreement and the Plan. Optionholder acknowledges and agrees that this Stock Option Grant Notice and the Option Agreement may not be modified, amended or revised except as
provided in the Plan. Optionholder further acknowledges that as of the Date of Grant, this Stock Option Grant Notice, the Option Agreement, and the Plan set forth the entire understanding between Optionholder and the Company regarding this option
award and supersede all prior oral and written agreements, promises and/or representations on that subject with the exception of, if applicable, (i) equity awards previously granted and delivered to Optionholder, (ii) any compensation
recovery policy that is adopted by the Company or is otherwise required by applicable law and (iii) any written employment or severance arrangement or other written agreement entered into between the Company and Optionholder specifying the
terms that should govern this option upon the terms and conditions set forth therein. 
 By accepting this option, Optionholder acknowledges
having received and read the Stock Option Grant Notice, the Option Agreement and the Plan and agrees to all of the terms and conditions set forth in these documents. Optionholder consents to receive Plan and related documents by electronic delivery
and to participate in the Plan through an on-line or electronic system established and maintained by the Company or another third party designated by the Company. 

 

					
	 SYNTHORX, INC.
  

By:                       
                                         
                                         
       
 Signature

Title:                      
                                         
                                         
     
  

Date:                      
                                         
                                         
     
	  	 
 

            
	  	 OPTIONHOLDER:
  

 
 Signature

Date:                      
                                         
                                        



  

ATTACHMENTS: Option Agreement, 2018 Equity Incentive Plan and Notice of Exercise 

  
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 ATTACHMENT I 

SYNTHORX, INC. 

OPTION AGREEMENT 

(2018 EQUITY INCENTIVE PLAN) 

(INCENTIVE STOCK OPTION OR NONSTATUTORY STOCK
OPTION) 
 Pursuant to your Stock Option Grant Notice (“Grant Notice”) and this
Option Agreement, Synthorx, Inc. (the “Company”) has granted you an option under its 2018 Equity Incentive Plan (the “Plan”) to purchase the number of shares of the Company’s Common Stock
indicated in your Grant Notice at the exercise price indicated in your Grant Notice. The option is granted to you effective as of the date of grant set forth in the Grant Notice (the “Date of Grant”). If there is any conflict
between the terms in this Option Agreement and the Plan, the terms of the Plan will control. Capitalized terms not explicitly defined in this Option Agreement or in the Grant Notice but defined in the Plan will have the same definitions as in the
Plan. 
 The details of your option, in addition to those set forth in the Grant Notice and the Plan, are as follows: 

1.            VESTING. Subject to the
provisions contained herein, your option will vest as provided in your Grant Notice. Vesting will cease upon the termination of your Continuous Service. 

(a)        In the event of a Change in Control in which the surviving
corporation or acquiring corporation (or its parent company) assumes or continues your option or substitutes a similar stock award for such option, then the portion of your option that has not vested as of the effective time of such Change in
Control shall continue to vest according to the vesting schedule in your Grant Notice; provided that such portion of your option shall vest no less favorably than ratably over the twelve (12) month period following the Change in Control.
Notwithstanding the foregoing, if a Change in Control occurs and within three (3) months prior to, or within twelve (12) months after, the effective time of such Change in Control, your Continuous Service terminates due to an involuntary
termination (not including death or Disability) without Cause or due to your voluntary termination with Good Reason, then, as of the date of termination of Continuous Service, the vesting and exercisability of your option will be accelerated in
full. 
 (b)        “Good Reason” means the
occurrence of any of the following events, conditions or actions taken by the Company without your written consent: (i) a material reduction of your annual base salary; provided, however, that Good Reason shall not be deemed to have
occurred in the event of a reduction in your annual base salary that is pursuant to a salary reduction program affecting substantially all of the similarly situated employees of the Company and that does not adversely affect you to a greater extent
than other similarly situated employees; (ii) a material reduction in your authority, duties or responsibilities; (iii) a relocation of your principal place of employment with the Company to a place that increases your one-way commute by more than fifty (50) miles as compared to your then-current principal place of employment immediately prior to such relocation (excluding regular travel in the ordinary course of business);
(iv) in the case of employees reporting to the Board or the Company’s Chief Executive Officer, a material adverse change in such reporting level requiring you to report to a corporate officer or executive other than the Board or the
Company’s Chief Executive Officer, as the case may be; or (v) a material breach by the Company of any material agreement between you and the Company; provided, however, that in each case above, in order for your resignation to be
deemed to have been for Good Reason, you must first give the Board written notice of the action or omission giving rise to “Good 

  
 1 













 
Reason” within ninety (90) days after the first occurrence thereof; the Company must fail to reasonably cure such action or omission within thirty (30) days after receipt of such
notice (the “Cure Period”), and your resignation from all positions you hold with the Company must be effective not later than thirty (30) days after the expiration of such Cure Period. 

(c)        If any payment or benefit you would receive from the Company or
otherwise in connection with a Change in Control or other similar transaction (a “280G Payment”) would (i) constitute a “parachute payment” within the meaning of Section 280G of the Code, and (ii) but
for this sentence, be subject to the excise tax imposed by Section 4999 of the Code (the “Excise Tax”), then any such 280G Payment (a “Payment”) shall be equal to the Reduced Amount. The
“Reduced Amount” shall be either (x) the largest portion of the Payment that would result in no portion of the Payment (after reduction) being subject to the Excise Tax or (y) the largest portion, up to and
including the total, of the Payment, whichever amount (i.e., the amount determined by clause (x) or by clause (y)), after taking into account all applicable federal, state and local employment taxes, income taxes, and the Excise Tax (all
computed at the highest applicable marginal rate), results in your receipt, on an after-tax basis, of the greater economic benefit notwithstanding that all or some portion of the Payment may be subject to the
Excise Tax. If a reduction in a Payment is required pursuant to the preceding sentence and the Reduced Amount is determined pursuant to clause (x) of the preceding sentence, the reduction shall occur in the manner (the “Reduction
Method”) that results in the greatest economic benefit for you. If more than one method of reduction will result in the same economic benefit, the items so reduced will be reduced pro rata (the “Pro Rata Reduction
Method”). 
 Notwithstanding the foregoing, if the Reduction Method or the Pro Rata Reduction Method would
result in any portion of the Payment being subject to taxes pursuant to Section 409A of the Code that would not otherwise be subject to taxes pursuant to Section 409A of the Code, then the Reduction Method and/or the Pro Rata Reduction
Method, as the case may be, shall be modified so as to avoid the imposition of taxes pursuant to Section 409A of the Code as follows: (A) as a first priority, the modification shall preserve to the greatest extent possible, the greatest
economic benefit for you as determined on an after-tax basis; (B) as a second priority, Payments that are contingent on future events (e.g., being terminated without cause), shall be reduced (or
eliminated) before Payments that are not contingent on future events; and (C) as a third priority, Payments that are “deferred compensation” within the meaning of Section 409A of the Code shall be reduced (or eliminated) before
Payments that are not deferred compensation within the meaning of Section 409A of the Code. 
 Unless you and the
Company agree on an alternative accounting firm, at the Company’s election, either (i) Ernst & Young LLP or (ii) the accounting firm engaged by the Company for general tax compliance purposes as of the day prior to the
effective date of the change of control transaction triggering the Payment shall perform the foregoing calculations. If the accounting firm so engaged by the Company is serving as accountant or auditor for the individual, entity or group effecting
the change of control transaction, the Company shall appoint a nationally recognized accounting firm to make the determinations required hereunder. The Company shall bear all expenses with respect to the determinations by such accounting firm
required to be made hereunder. The Company shall use commercially reasonable efforts to cause the accounting firm engaged to make the determinations hereunder to provide its calculations, together with detailed supporting documentation, to you and
the Company within fifteen (15) calendar days after the date on which your right to a 280G Payment becomes reasonably likely to occur (if requested at that time by you or the Company) or such other time as requested by you or the Company. 

If you receive a Payment for which the Reduced Amount was determined pursuant to clause (x) of the first paragraph of
this Section 1(c) and the Internal Revenue Service determines thereafter that some portion of the Payment is subject to the Excise Tax, you shall promptly return to the Company a 

  
 2 













 
sufficient amount of the Payment (after reduction pursuant to clause (x) of the first paragraph of this Section 1(c) so that no portion of the remaining Payment is subject to the Excise
Tax. For the avoidance of doubt, if the Reduced Amount was determined pursuant to clause (y) in the first paragraph of this Section 1(c), you shall have no obligation to return any portion of the Payment pursuant to the preceding sentence.

 2.        NUMBER OF SHARES
AND EXERCISE PRICE. The number of shares of Common Stock subject to your option and your exercise price per share in your Grant Notice will be adjusted for Capitalization Adjustments. 

3.        EXERCISE RESTRICTION
FOR NON-EXEMPT EMPLOYEES. If you are an Employee eligible for overtime compensation under the Fair Labor Standards Act of 1938, as amended (that
is, a “Non-Exempt Employee”), and except as otherwise provided in the Plan, you may not exercise your option until you have completed at least six (6) months of Continuous Service
measured from the Date of Grant, even if you have already been an employee for more than six (6) months. Consistent with the provisions of the Worker Economic Opportunity Act, you may exercise your option as to any vested portion prior to such
six (6) month anniversary in the case of (i) your death or disability, (ii) a Corporate Transaction in which your option is not assumed, continued or substituted, (iii) a Change in Control or (iv) your termination of
Continuous Service on your “retirement” (as defined in the Company’s benefit plans). 

4.        METHOD OF
PAYMENT. You must pay the full amount of the exercise price for the shares you wish to exercise. You may pay the exercise price in cash or by check, bank draft or money order payable to the Company or in any other manner
permitted by your Grant Notice, which may include one or more of the following: 

(a)        Provided that at the time of exercise the Common Stock is publicly
traded, pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board that, prior to the issuance of Common Stock, results in either the receipt of cash (or check) by the Company or the receipt of irrevocable
instructions to pay the aggregate exercise price to the Company from the sales proceeds. This manner of payment is also known as a “broker-assisted exercise”, “same day sale”, or “sell to cover”. 

(b)        Provided that at the time of exercise the Common Stock is publicly
traded, by delivery to the Company (either by actual delivery or attestation) of already-owned shares of Common Stock that are owned free and clear of any liens, claims, encumbrances or security interests, and that are valued at Fair Market Value on
the date of exercise. “Delivery” for these purposes, in the sole discretion of the Company at the time you exercise your option, will include delivery to the Company of your attestation of ownership of such shares of Common Stock in a form
approved by the Company. You may not exercise your option by delivery to the Company of Common Stock if doing so would violate the provisions of any law, regulation or agreement restricting the redemption of the Company’s stock. 

(c)        If this option is a Nonstatutory Stock Option, subject to the
consent of the Company at the time of exercise, by a “net exercise” arrangement pursuant to which the Company will reduce the number of shares of Common Stock issued upon exercise of your option by the largest whole number of shares with a
Fair Market Value that does not exceed the aggregate exercise price. You must pay any remaining balance of the aggregate exercise price not satisfied by the “net exercise” in cash or other permitted form of payment. Shares of Common Stock
will no longer be outstanding under your option and will not be exercisable thereafter if those shares (i) are used to pay the exercise price pursuant to the “net exercise,” (ii) are delivered to you as a result of such exercise, and
(iii) are withheld to satisfy your tax withholding obligations. 

  
 3 














5.            WHOLE
SHARES. You may exercise your option only for whole shares of Common Stock. 

6.            SECURITIES
LAW COMPLIANCE. In no event may you exercise your option unless the shares of Common Stock issuable upon exercise are then registered under the Securities Act or, if not registered, the Company has determined that
your exercise and the issuance of the shares would be exempt from the registration requirements of the Securities Act. The exercise of your option also must comply with all other applicable laws and regulations governing your option, and you may not
exercise your option if the Company determines that such exercise would not be in material compliance with such laws and regulations (including any restrictions on exercise required for compliance with Treas. Reg.
1.401(k)-1(d)(3), if applicable). 

7.            TERM. You may not
exercise your option before the Date of Grant or after the expiration of the option’s term. The term of your option expires, subject to the provisions of Section 5(h) of the Plan, upon the earliest of the following: 

(a)        immediately upon the termination of your Continuous Service for
Cause; 
 (b)        three (3) months after the termination of your
Continuous Service for any reason other than Cause, your Disability or your death (except as otherwise provided in Section 7(d) below); provided, however, that if during any part of such three (3) month period your option is
not exercisable solely because of the condition set forth in the section above regarding “Securities Law Compliance,” your option will not expire until the earlier of the Expiration Date or until it has been exercisable for an aggregate
period of three (3) months after the termination of your Continuous Service; provided further, if during any part of such three (3) month period, the sale of any Common Stock received upon exercise of your option would violate the
Company’s insider trading policy, then you must notify the Company no later than the day on which your Continuous Service terminates, and the Company may extend the period of time in which your option will remain exercisable, at the
Company’s sole discretion, until the earlier of the Expiration Date or until the option has been exercisable for an aggregate period of three (3) months after the termination of your Continuous Service during which the sale of the Common
Stock received upon exercise of your option would not be in violation of the Company’s insider trading policy. Notwithstanding the foregoing, if (i) you are a Non-Exempt Employee, (ii) your
Continuous Service terminates within six (6) months after the Date of Grant, and (iii) you have vested in a portion of your option at the time of your termination of Continuous Service, your option will not expire until the earlier of
(x) the later of (A) the date that is seven (7) months after the Date of Grant, and (B) the date that is three (3) months after the termination of your Continuous Service, and (y) the Expiration Date; 

(c)        twelve (12) months after the termination of your Continuous
Service due to your Disability (except as otherwise provided in Section 7(d) below); 

(d)        eighteen (18) months after your death if you die either during
your Continuous Service or within three (3) months after your Continuous Service terminates for any reason other than Cause; 

(e)        the Expiration Date indicated in your Grant Notice; or 

(f)        the day before the tenth (10th) anniversary of the Date of Grant.

 If your option is an Incentive Stock Option, note that to obtain the federal income tax advantages associated with an
Incentive Stock Option, the Code requires that at all times beginning on the Date of Grant and ending on the day three (3) months before the date of your option’s exercise, you must be an 

  
 4 













 
employee of the Company or an Affiliate, except in the event of your death or Disability. The Company has provided for extended exercisability of your option under certain circumstances for your
benefit but cannot guarantee that your option will necessarily be treated as an Incentive Stock Option if you continue to provide services to the Company or an Affiliate as a Consultant or Director after your employment terminates or if you
otherwise exercise your option more than three (3) months after the date your employment with the Company or an Affiliate terminates. 

8.            EXERCISE. 

(a)        You may exercise the vested portion of your option (and the
unvested portion of your option if your Grant Notice so permits) during its term by (i) delivering a Notice of Exercise (in a form designated by the Company) or completing such other documents and/or procedures designated by the Company for
exercise and (ii) paying the exercise price and any applicable withholding taxes to the Company’s Secretary, stock plan administrator, or such other person as the Company may designate, together with such additional documents as the
Company may then require. 
 (b)        By exercising your option you agree
that, as a condition to any exercise of your option, the Company may require you to enter into an arrangement providing for the payment by you to the Company of any tax withholding obligation of the Company arising by reason of (i) the exercise
of your option, (ii) the lapse of any substantial risk of forfeiture to which the shares of Common Stock are subject at the time of exercise, or (iii) the disposition of shares of Common Stock acquired upon such exercise. 

(c)        If your option is an Incentive Stock Option, by exercising your
option you agree that you will notify the Company in writing within fifteen (15) days after the date of any disposition of any of the shares of the Common Stock issued upon exercise of your option that occurs within two (2) years after the
Date of Grant or within one (1) year after such shares of Common Stock are transferred upon exercise of your option. 

(d)        By accepting your option you agree that you will not sell, dispose
of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale with respect to any shares of Common Stock or other securities of the Company held
by you, for a period of one hundred eighty (180) days following the effective date of a registration statement of the Company filed under the Securities Act or such longer period as the underwriters or the Company will request to facilitate
compliance with FINRA Rule 2241 or any successor or similar rules or regulation (the “Lock-Up Period”); provided, however, that nothing contained in this section will prevent the
exercise of a repurchase option, if any, in favor of the Company during the Lock-Up Period. You further agree to execute and deliver such other agreements as may be reasonably requested by the Company or the
underwriters that are consistent with the foregoing 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 your shares of Common Stock until
the end of such period. You also agree that any transferee of any shares of Common Stock (or other securities) of the Company held by you will be bound by this Section 8(d). The underwriters of the Company’s stock are intended third party
beneficiaries of this Section 8(d) and will have the right, power and authority to enforce the provisions hereof as though they were a party hereto. 

9.            TRANSFERABILITY. Except
as otherwise provided in this Section 9, your option is not transferable, except by will or by the laws of descent and distribution, and is exercisable during your life only by you. 

  
 5 













 (a)        Certain
Trusts. Upon receiving written permission from the Board or its duly authorized designee, you may transfer your option to a trust if you are considered to be the sole beneficial owner (determined under Section 671 of the Code and applicable
state law) while the option is held in the trust. You and the trustee must enter into transfer and other agreements required by the Company. 

(b)        Domestic Relations Orders. Upon receiving written permission
from the Board or its duly authorized designee, and provided that you and the designated transferee enter into transfer and other agreements required by the Company, you may transfer your option pursuant to the terms of a domestic relations order,
official marital settlement agreement or other divorce or separation instrument as permitted by Treasury Regulation 1.421-1(b)(2) that contains the information required by the Company to effectuate the
transfer. You are encouraged to discuss the proposed terms of any division of this option with the Company prior to finalizing the domestic relations order or marital settlement agreement to help ensure the required information is contained within
the domestic relations order or marital settlement agreement. If this option is an Incentive Stock Option, this option may be deemed to be a Nonstatutory Stock Option as a result of such transfer. 

(c)        Beneficiary Designation. Upon receiving written permission
from the Board or its duly authorized designee, you may, by delivering written notice to the Company, in a form approved by the Company and any broker designated by the Company to handle option exercises, designate a third party who, on your death,
will thereafter be entitled to exercise this option and receive the Common Stock or other consideration resulting from such exercise. In the absence of such a designation, your executor or administrator of your estate will be entitled to exercise
this option and receive, on behalf of your estate, the Common Stock or other consideration resulting from such exercise. 

10.           OPTION NOT
A SERVICE CONTRACT. Your option is not an employment or service contract, and nothing in your option will be deemed to create in any way whatsoever any obligation on your part to continue in the
employ of the Company or an Affiliate, or of the Company or an Affiliate to continue your employment. In addition, nothing in your option will obligate the Company or an Affiliate, their respective stockholders, boards of directors, officers or
employees to continue any relationship that you might have as a Director or Consultant for the Company or an Affiliate. 

11.           WITHHOLDING
OBLIGATIONS. 
 (a)        At the time you exercise your
option, in whole or in part, and at any time thereafter as requested by the Company, you hereby authorize withholding from payroll and any other amounts payable to you, and otherwise agree to make adequate provision for (including by means of a
“same day sale” pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board to the extent permitted by the Company), any sums required to satisfy the federal, state, local and foreign tax withholding
obligations of the Company or an Affiliate, if any, which arise in connection with the exercise of your option. 

(b)        If this option is a Nonstatutory Stock Option, then upon your
request and subject to approval by the Company, and compliance with any applicable legal conditions or restrictions, the Company may withhold from fully vested shares of Common Stock otherwise issuable to you upon the exercise of your option a
number of whole shares of Common Stock having a Fair Market Value, determined by the Company as of the date of exercise, not in excess of the maximum amount of tax permitted to be withheld by law (or such lower amount as may be necessary to avoid
classification of your option as a liability for financial accounting purposes). 

  
 6 













 (c)        You may not
exercise your option unless the tax withholding obligations of the Company and/or any Affiliate are satisfied. Accordingly, you may not be able to exercise your option when desired even though your option is vested, and the Company will have no
obligation to issue a certificate for such shares of Common Stock or release such shares of Common Stock from any escrow provided for herein, if applicable, unless such obligations are satisfied. 

12.            TAX
CONSEQUENCES. You hereby agree that the Company does not have a duty to design or administer the Plan or its other compensation programs in a manner that minimizes your tax liabilities. You will not make any claim
against the Company, or any of its Officers, Directors, Employees or Affiliates related to tax liabilities arising from your option or your other compensation. In particular, you acknowledge that this option is exempt from Section 409A of the
Code only if the exercise price per share specified in the Grant Notice is at least equal to the “fair market value” per share of the Common Stock on the Date of Grant and there is no other impermissible deferral of compensation associated
with the option. 

13.            NOTICES. Any notices
provided for in your option or the Plan will be given in writing (including electronically) and will be deemed effectively given upon receipt or, in the case of notices delivered by mail by the Company to you, five (5) days after deposit in the
United States mail, postage prepaid, addressed to you at the last address you provided to the Company. The Company may, in its sole discretion, decide to deliver any documents related to participation in the Plan and this option by electronic means
or to request your consent to participate in the Plan by electronic means. By accepting this option, you consent to receive such documents by electronic delivery and to participate in the Plan through an
on-line or electronic system established and maintained by the Company or another third party designated by the Company. 

14.            GOVERNING
PLAN DOCUMENT. Your option is subject to all the provisions of the Plan, the provisions of which are hereby made a part of your option, and is further subject to all interpretations, amendments, rules and
regulations, which may from time to time be promulgated and adopted pursuant to the Plan. If there is any conflict between the provisions of your option and those of the Plan, the provisions of the Plan will control. In addition, your option (and
any compensation paid or shares issued under your option) is subject to recoupment in accordance with The Dodd–Frank Wall Street Reform and Consumer Protection Act and any implementing regulations thereunder, any clawback policy adopted by the
Company and any compensation recovery policy otherwise required by applicable law. 

15.            OTHER
DOCUMENTS. You hereby acknowledge receipt of and the right to receive a document providing the information required by Rule 428(b)(1) promulgated under the Securities Act, which includes the Plan prospectus. In addition, you
acknowledge receipt of the Company’s policy permitting certain individuals to sell shares only during certain “window” periods and the Company’s insider trading policy, in effect from time to time. 

16.            EFFECT ON
OTHER EMPLOYEE BENEFIT PLANS. The value of this option will not be included as compensation, earnings, salaries, or other similar terms used when calculating your benefits under any
employee benefit plan sponsored by the Company or any Affiliate, except as such plan otherwise expressly provides. The Company expressly reserves its rights to amend, modify, or terminate any of the Company’s or any Affiliate’s employee
benefit plans. 
 17.            VOTING
RIGHTS. You will not have voting or any other rights as a stockholder of the Company with respect to the shares to be issued pursuant to this option until such shares are issued to you. Upon such issuance, you will obtain full
voting and other rights as a stockholder of the Company. Nothing contained in this option, and no action taken pursuant to its provisions, will create or be 

  
 7 













 
construed to create a trust of any kind or a fiduciary relationship between you and the Company or any other person. 

18.          SEVERABILITY. If all or any part
of this Option Agreement or the Plan is declared by any court or governmental authority to be unlawful or invalid, such unlawfulness or invalidity will not invalidate any portion of this Option Agreement or the Plan not declared to be unlawful or
invalid. Any Section of this Option Agreement (or part of such a Section) so declared to be unlawful or invalid shall, if possible, be construed in a manner which will give effect to the terms of such Section or part of a Section to the fullest
extent possible while remaining lawful and valid. 

19.          MISCELLANEOUS. 

(a)        The rights and obligations of the Company under your option will be
transferable to any one or more persons or entities, and all covenants and agreements hereunder will inure to the benefit of, and be enforceable by the Company’s successors and assigns. 

(b)        You agree upon request to execute any further documents or
instruments necessary or desirable in the sole determination of the Company to carry out the purposes or intent of your option. 

(c)        You acknowledge and agree that you have reviewed your option in its
entirety, have had an opportunity to obtain the advice of counsel prior to executing and accepting your option, and fully understand all provisions of your option. 

(d)        This Option Agreement will be subject to all applicable laws,
rules, and regulations, and to such approvals by any governmental agencies or national securities exchanges as may be required. 

(e)        All obligations of the Company under the Plan and this Option
Agreement will be binding on any successor to the Company, whether the existence of such successor is the result of a direct or indirect purchase, merger, consolidation, or otherwise, of all or substantially all of the business and/or assets of the
Company. 
 *        *        * 

This Option Agreement will be deemed to be signed by you upon the signing by you of the Stock Option Grant Notice to which it
is attached. 

  
 8 













 ATTACHMENT II 

2018 EQUITY INCENTIVE PLAN 

  
 1 













 ATTACHMENT III 

NOTICE OF EXERCISE 

 

			
	 SYNTHORX, INC.

11099 N. Torrey Pines Road, Suite 290        

La Jolla, California 92037
	  	  
 Date of Exercise: _______________


 This constitutes notice to Synthorx, Inc. (the “Company”) under my
stock option that I elect to purchase the below number of shares of Common Stock of the Company (the “Shares”) for the price set forth below. 
  

									
	 Type of option (check one):
	  	 	Incentive ☐	 	 	 	Nonstatutory ☐	 
			
	 Stock option dated:
	  				 			
		  	  
	  
	 	 	  
	  
	 
			
	 Number of Shares as to which option is exercised:
	  				 			
		  	  
	  
	 	 	  
	  
	 
			
	 Certificates to be issued in name of:
	  				 			
		  	  
	  
	 	 	  
	  
	 
			
	 Total exercise price:
	  	$	______________	 	 	$	______________	 
			
	 Cash payment delivered herewith:
	  	$	______________	 	 	$	______________	 
			
	 [Value of ________ Shares delivered
herewith1:
	  	$	______________	 	 	$	______________	] 
			
	 [Value of ________ Shares pursuant to net
exercise2:
	  	$	______________	 	 	$	______________	] 
			
	 [Regulation T Program (cashless
exercise3):
	  	$	______________	 	 	$	______________	] 

  
  
  

 
 1           Shares must meet the public trading requirements set forth in the option. Shares must be valued in accordance with the terms of the option
being exercised, and must be owned free and clear of any liens, claims, encumbrances or security interests. Certificates must be endorsed or accompanied by an executed assignment separate from certificate. 

2           The option must be a
Nonstatutory Stock Option, and the Company must have established net exercise procedures at the time of exercise, in order to utilize this payment method. 

3           Shares must meet the public
trading requirements set forth in the option. 

  
 1 













 By this exercise, I agree (i) to provide such additional documents as
you may require pursuant to the terms of the Synthorx, Inc. 2018 Equity Incentive Plan, (ii) to provide for the payment by me to you (in the manner designated by you) of your withholding obligation, if any, relating to the exercise of this
option, and (iii) if this exercise relates to an incentive stock option, to notify you in writing within fifteen (15) days after the date of any disposition of any of the Shares issued upon exercise of this option that occurs within two
(2) years after the date of grant of this option or within one (1) year after such Shares are issued upon exercise of this option. 

I further agree that, if required by the Company (or a representative of the underwriters) in connection with the first
underwritten registration of the offering of any securities of the Company under the Securities Act, I will not sell, dispose of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar
transaction with the same economic effect as a sale with respect to any shares of Common Stock or other securities of the Company for a period of one hundred eighty (180) days following the effective date of a registration statement of the
Company filed under the Securities Act (or such longer period as the underwriters or the Company shall request to facilitate compliance with FINRA Rule 2241 or any successor or similar rule or regulation) (the “Lock-Up Period”). I further agree to execute and deliver such other agreements as may be reasonably requested by the Company or the underwriters that are consistent with the foregoing 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 securities subject to the foregoing restrictions until
the end of such period. 
  
  

	
	 Very truly yours,
  

 




  
 2 













 Director Form 

SYNTHORX, INC. 

STOCK OPTION GRANT NOTICE 

(2018 EQUITY INCENTIVE PLAN) 

Synthorx, Inc. (the “Company”), pursuant to its 2018 Equity Incentive Plan (the
“Plan”), hereby grants to Optionholder an option to purchase the number of shares of the Company’s Common Stock set forth below. This option is subject to all of the terms and conditions as set forth in this Stock Option
Grant Notice, in the Option Agreement, the Plan and the Notice of Exercise, all of which are attached hereto and incorporated herein in their entirety. Capitalized terms not explicitly defined herein but defined in the Plan or the Option Agreement
will have the same definitions as in the Plan or the Option Agreement. If there is any conflict between the terms in this Stock Option Grant Notice and the Plan, the terms of the Plan will control. 

 

					
	 Optionholder:
	 	  
	 	
	 Date of Grant:
	 	  
	 	
	 Vesting Commencement Date:
	 	  
	 	
	 Number of Shares Subject to Option:
	 	  
	 	
	 Exercise Price (Per Share):
	 	  
	 	
	 Total Exercise Price:
	 	  
	 	
	 Expiration Date:
	 	  
	 	

  

			
	 Type of Grant:
	 	 Nonstatutory Stock Option

		
	 Exercise Schedule:    
	 	 Same as Vesting Schedule

		
	 Vesting Schedule:
	 	 [Initial Grant: The shares subject to the option shall vest in thirty-six
(36) successive equal monthly installments measured from the Date of Grant][Annual Grant: The shares subject to the option shall vest in twelve (12) successive equal monthly installments measured from the Date of Grant], subject to
Optionholder’s Continuous Service as of each such date and the potential vesting acceleration described in Section 1 of the Option Agreement.

		
	 Payment:
	 	 By one or a combination of the following items (described in the Option Agreement):

		
		 	 ☒   By cash, check, bank draft or money order payable to
the Company

		 	 ☒   Pursuant to a Regulation T Program if the shares are
publicly traded

		 	 ☐   By delivery of already-owned shares if the shares are
publicly traded

		 	 ☐   Subject to the Company’s consent at the time of
exercise, by a “net exercise” arrangement



  
 1. 













 Additional Terms/Acknowledgements: Optionholder acknowledges receipt of, and
understands and agrees to, this Stock Option Grant Notice, the Option Agreement and the Plan. Optionholder acknowledges and agrees that this Stock Option Grant Notice and the Option Agreement may not be modified, amended or revised except as
provided in the Plan. Optionholder further acknowledges that as of the Date of Grant, this Stock Option Grant Notice, the Option Agreement, and the Plan set forth the entire understanding between Optionholder and the Company regarding this option
award and supersede all prior oral and written agreements, promises and/or representations on that subject with the exception of, if applicable, (i) equity awards previously granted and delivered to Optionholder, (ii) any compensation
recovery policy that is adopted by the Company or is otherwise required by applicable law and (iii) any written employment or severance arrangement or other written agreement entered into between the Company and Optionholder specifying the
terms that should govern this option upon the terms and conditions set forth therein. 
 By accepting this option, Optionholder acknowledges
having received and read the Stock Option Grant Notice, the Option Agreement and the Plan and agrees to all of the terms and conditions set forth in these documents. Optionholder consents to receive Plan and related documents by electronic delivery
and to participate in the Plan through an on-line or electronic system established and maintained by the Company or another third party designated by the Company. 

 

					
	 SYNTHORX, INC.
  

By:                       
                                         
                                         
       
 Signature

 

Title:                      
                                         
                                         
     
  

Date:                      
                                         
                                         
     
	  	 
 

            
	  	 OPTIONHOLDER:
  

 
 Signature

 

Date:                      
                                         
                                        



 ATTACHMENTS: Option Agreement, 2018 Equity Incentive Plan and
Notice of Exercise 
  

  
 2 













 ATTACHMENT I 

SYNTHORX, INC. 

OPTION AGREEMENT 

(2018 EQUITY INCENTIVE PLAN) 

(NONSTATUTORY STOCK OPTION) 

Pursuant to your Stock Option Grant Notice (“Grant Notice”) and this Option Agreement, Synthorx, Inc.
(the “Company”) has granted you an option under its 2018 Equity Incentive Plan (the “Plan”) to purchase the number of shares of the Company’s Common Stock indicated in your Grant Notice at the
exercise price indicated in your Grant Notice. The option is granted to you effective as of the date of grant set forth in the Grant Notice (the “Date of Grant”). If there is any conflict between the terms in this Option
Agreement and the Plan, the terms of the Plan will control. Capitalized terms not explicitly defined in this Option Agreement or in the Grant Notice but defined in the Plan will have the same definitions as in the Plan. 

The details of your option, in addition to those set forth in the Grant Notice and the Plan, are as follows: 

1.        VESTING. 

(a)        Subject to the provisions contained herein, your option will vest as
provided in your Grant Notice. Vesting will cease upon the termination of your Continuous Service. Notwithstanding the foregoing, if a Change in Control occurs and your Continuous Service has not terminated as of immediately prior to such Change in
Control, the vesting and exercisability of your option will be accelerated in full. 

(b)        If any payment or benefit you would receive from the Company or
otherwise in connection with a Change in Control or other similar transaction (a “280G Payment”) would (i) constitute a “parachute payment” within the meaning of Section 280G of the Code, and (ii) but
for this sentence, be subject to the excise tax imposed by Section 4999 of the Code (the “Excise Tax”), then any such 280G Payment (a “Payment”) shall be equal to the Reduced Amount. The
“Reduced Amount” shall be either (x) the largest portion of the Payment that would result in no portion of the Payment (after reduction) being subject to the Excise Tax or (y) the largest portion, up to and
including the total, of the Payment, whichever amount (i.e., the amount determined by clause (x) or by clause (y)), after taking into account all applicable federal, state and local employment taxes, income taxes, and the Excise Tax (all
computed at the highest applicable marginal rate), results in your receipt, on an after-tax basis, of the greater economic benefit notwithstanding that all or some portion of the Payment may be subject to the
Excise Tax. If a reduction in a Payment is required pursuant to the preceding sentence and the Reduced Amount is determined pursuant to clause (x) of the preceding sentence, the reduction shall occur in the manner (the “Reduction
Method”) that results in the greatest economic benefit for you. If more than one method of reduction will result in the same economic benefit, the items so reduced will be reduced pro rata (the “Pro Rata Reduction
Method”). 
 Notwithstanding the foregoing, if the Reduction Method or the Pro Rata Reduction Method would
result in any portion of the Payment being subject to taxes pursuant to Section 409A of the Code that would not otherwise be subject to taxes pursuant to Section 409A of the Code, then the Reduction Method and/or the Pro Rata Reduction
Method, as the case may be, shall be modified so as to avoid the imposition of taxes pursuant to Section 409A of the Code as follows: (A) as a first priority, the 

  
 1 













 
modification shall preserve to the greatest extent possible, the greatest economic benefit for you as determined on an after-tax basis; (B) as a
second priority, Payments that are contingent on future events (e.g., being terminated without cause), shall be reduced (or eliminated) before Payments that are not contingent on future events; and (C) as a third priority, Payments that are
“deferred compensation” within the meaning of Section 409A of the Code shall be reduced (or eliminated) before Payments that are not deferred compensation within the meaning of Section 409A of the Code. 

Unless you and the Company agree on an alternative accounting firm, at the Company’s election, either
(i) Ernst & Young LLP or (ii) the accounting firm engaged by the Company for general tax compliance purposes as of the day prior to the effective date of the change of control transaction triggering the Payment shall perform the
foregoing calculations. If the accounting firm so engaged by the Company is serving as accountant or auditor for the individual, entity or group effecting the change of control transaction, the Company shall appoint a nationally recognized
accounting firm to make the determinations required hereunder. The Company shall bear all expenses with respect to the determinations by such accounting firm required to be made hereunder. The Company shall use commercially reasonable efforts to
cause the accounting firm engaged to make the determinations hereunder to provide its calculations, together with detailed supporting documentation, to you and the Company within fifteen (15) calendar days after the date on which your right to
a 280G Payment becomes reasonably likely to occur (if requested at that time by you or the Company) or such other time as requested by you or the Company. 

If you receive a Payment for which the Reduced Amount was determined pursuant to clause (x) of the first paragraph of
this Section 1(b) and the Internal Revenue Service determines thereafter that some portion of the Payment is subject to the Excise Tax, you shall promptly return to the Company a sufficient amount of the Payment (after reduction pursuant to
clause (x) of the first paragraph of this Section 1(b) so that no portion of the remaining Payment is subject to the Excise Tax. For the avoidance of doubt, if the Reduced Amount was determined pursuant to clause (y) in the first
paragraph of this Section 1(b), you shall have no obligation to return any portion of the Payment pursuant to the preceding sentence. 

2.        NUMBER OF SHARES
AND EXERCISE PRICE. The number of shares of Common Stock subject to your option and your exercise price per share in your Grant Notice will be adjusted for Capitalization Adjustments. 

3.        METHOD OF
PAYMENT. You must pay the full amount of the exercise price for the shares you wish to exercise. You may pay the exercise price in cash or by check, bank draft or money order payable to the Company or in any other manner
permitted by your Grant Notice, which may include one or more of the following: 

(a)        Provided that at the time of exercise the Common Stock is publicly
traded, pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board that, prior to the issuance of Common Stock, results in either the receipt of cash (or check) by the Company or the receipt of irrevocable
instructions to pay the aggregate exercise price to the Company from the sales proceeds. This manner of payment is also known as a “broker-assisted exercise”, “same day sale”, or “sell to cover”. 

(b)        Provided that at the time of exercise the Common Stock is publicly
traded, by delivery to the Company (either by actual delivery or attestation) of already-owned shares of Common Stock that are owned free and clear of any liens, claims, encumbrances or security interests, and that are valued at Fair Market Value on
the date of exercise. “Delivery” for these purposes, in the sole discretion of the Company at the time you exercise your option, will include delivery to the Company of your 

  
 2 













 
attestation of ownership of such shares of Common Stock in a form approved by the Company. You may not exercise your option by delivery to the Company of Common Stock if doing so would violate
the provisions of any law, regulation or agreement restricting the redemption of the Company’s stock. 

(c)        Subject to the consent of the Company at the time of exercise, by a
“net exercise” arrangement pursuant to which the Company will reduce the number of shares of Common Stock issued upon exercise of your option by the largest whole number of shares with a Fair Market Value that does not exceed the aggregate
exercise price. You must pay any remaining balance of the aggregate exercise price not satisfied by the “net exercise” in cash or other permitted form of payment. Shares of Common Stock will no longer be outstanding under your option and
will not be exercisable thereafter if those shares (i) are used to pay the exercise price pursuant to the “net exercise,” (ii) are delivered to you as a result of such exercise, and (iii) are withheld to satisfy your tax
withholding obligations. 
 4.        WHOLE
SHARES. You may exercise your option only for whole shares of Common Stock. 

5.        SECURITIES LAW
COMPLIANCE. In no event may you exercise your option unless the shares of Common Stock issuable upon exercise are then registered under the Securities Act or, if not registered, the Company has determined that your exercise and
the issuance of the shares would be exempt from the registration requirements of the Securities Act. The exercise of your option also must comply with all other applicable laws and regulations governing your option, and you may not exercise your
option if the Company determines that such exercise would not be in material compliance with such laws and regulations (including any restrictions on exercise required for compliance with Treas. Reg.
1.401(k)-1(d)(3), if applicable). 

6.        TERM. You may not exercise your option before
the Date of Grant or after the expiration of the option’s term. The term of your option expires, subject to the provisions of Section 5(h) of the Plan, upon the earliest of the following: 

(a)        immediately upon the termination of your Continuous Service for
Cause; 
 (b)        three (3) months after the termination of your
Continuous Service for any reason other than Cause, your Disability or your death (except as otherwise provided in Section 6(d) below); provided, however, that if during any part of such three (3) month period your option is
not exercisable solely because of the condition set forth in the section above regarding “Securities Law Compliance,” your option will not expire until the earlier of the Expiration Date or until it has been exercisable for an aggregate
period of three (3) months after the termination of your Continuous Service; provided further, if during any part of such three (3) month period, the sale of any Common Stock received upon exercise of your option would violate the
Company’s insider trading policy, then you must notify the Company no later than the date on which your Continuous Service terminates, and the Company may extend the period of time in which your option will remain exercisable, at the
Company’s sole discretion, until the earlier of the Expiration Date or until the option has been exercisable for an aggregate period of three (3) months after the termination of your Continuous Service during which the sale of the Common
Stock received upon exercise of your option would not be in violation of the Company’s insider trading policy. Notwithstanding the foregoing, if (i) you are a Non-Exempt Employee, (ii) your
Continuous Service terminates within six (6) months after the Date of Grant, and (iii) you have vested in a portion of your option at the time of your termination of Continuous Service, your option will not expire until the earlier of
(x) the later of (A) the date that is seven (7) months after the Date of Grant, and (B) the date that is three (3) months after the termination of your Continuous Service, and (y) the Expiration Date; 

  
 3 













 (c)        twelve
(12) months after the termination of your Continuous Service due to your Disability (except as otherwise provided in Section 6(d) below); 

(d)        eighteen (18) months after your death if you die either during
your Continuous Service or within three (3) months after your Continuous Service terminates for any reason other than Cause; 

(e)        the Expiration Date indicated in your Grant Notice; or 

(f)        the day before the tenth (10th) anniversary of the Date of Grant.

 7.        EXERCISE. 

(a)        You may exercise the vested portion of your option (and the
unvested portion of your option if your Grant Notice so permits) during its term by (i) delivering a Notice of Exercise (in a form designated by the Company) or completing such other documents and/or procedures designated by the Company for
exercise and (ii) paying the exercise price and any applicable withholding taxes to the Company’s Secretary, stock plan administrator, or such other person as the Company may designate, together with such additional documents as the
Company may then require. 
 (b)        By exercising your option you agree
that, as a condition to any exercise of your option, the Company may require you to enter into an arrangement providing for the payment by you to the Company of any tax withholding obligation of the Company arising by reason of (i) the exercise
of your option, (ii) the lapse of any substantial risk of forfeiture to which the shares of Common Stock are subject at the time of exercise, or (iii) the disposition of shares of Common Stock acquired upon such exercise. 

(c)        By accepting your option you agree that you will not sell, dispose
of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale with respect to any shares of Common Stock or other securities of the Company held
by you, for a period of one hundred eighty (180) days following the effective date of a registration statement of the Company filed under the Securities Act or such longer period as the underwriters or the Company will request to facilitate
compliance with FINRA Rule 2241 or any successor or similar rules or regulation (the “Lock-Up Period”); provided, however, that nothing contained in this section will prevent the
exercise of a repurchase option, if any, in favor of the Company during the Lock-Up Period. You further agree to execute and deliver such other agreements as may be reasonably requested by the Company or the
underwriters that are consistent with the foregoing 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 your shares of Common Stock until
the end of such period. You also agree that any transferee of any shares of Common Stock (or other securities) of the Company held by you will be bound by this Section 7(d). The underwriters of the Company’s stock are intended third party
beneficiaries of this Section 7(d) and will have the right, power and authority to enforce the provisions hereof as though they were a party hereto. 

8.        TRANSFERABILITY. Except as otherwise provided
in this Section 8, your option is not transferable, except by will or by the laws of descent and distribution, and is exercisable during your life only by you. 

(a)        Certain Trusts. Upon receiving written permission from the
Board or its duly authorized designee, you may transfer your option to a trust if you are considered to be the sole beneficial 

  
 4 













 
owner (determined under Section 671 of the Code and applicable state law) while the option is held in the trust. You and the trustee must enter into transfer and other agreements required by
the Company. 
 (b)        Domestic Relations Orders. Upon receiving
written permission from the Board or its duly authorized designee, and provided that you and the designated transferee enter into transfer and other agreements required by the Company, you may transfer your option pursuant to the terms of a domestic
relations order, official marital settlement agreement or other divorce or separation instrument as permitted by Treasury Regulation 1.421-1(b)(2) that contains the information required by the Company to
effectuate the transfer. You are encouraged to discuss the proposed terms of any division of this option with the Company prior to finalizing the domestic relations order or marital settlement agreement to help ensure the required information is
contained within the domestic relations order or marital settlement agreement. 

(c)        Beneficiary Designation. Upon receiving written permission
from the Board or its duly authorized designee, you may, by delivering written notice to the Company, in a form approved by the Company and any broker designated by the Company to handle option exercises, designate a third party who, on your death,
will thereafter be entitled to exercise this option and receive the Common Stock or other consideration resulting from such exercise. In the absence of such a designation, your executor or administrator of your estate will be entitled to exercise
this option and receive, on behalf of your estate, the Common Stock or other consideration resulting from such exercise. 

9.        OPTION NOT A
SERVICE CONTRACT. Your option is not an employment or service contract, and nothing in your option will be deemed to create in any way whatsoever any obligation on your part to continue in the employ of the Company
or an Affiliate, or of the Company or an Affiliate to continue your employment. In addition, nothing in your option will obligate the Company or an Affiliate, their respective stockholders, boards of directors, officers or employees to continue any
relationship that you might have as a Director or Consultant for the Company or an Affiliate. 

10.        WITHHOLDING OBLIGATIONS. 

(a)        At the time you exercise your option, in whole or in part, and at
any time thereafter as requested by the Company, you hereby authorize withholding from payroll and any other amounts payable to you, and otherwise agree to make adequate provision for (including by means of a “same day sale” pursuant to a
program developed under Regulation T as promulgated by the Federal Reserve Board to the extent permitted by the Company), any sums required to satisfy the federal, state, local and foreign tax withholding obligations of the Company or an Affiliate,
if any, which arise in connection with the exercise of your option. 

(b)        Upon your request and subject to approval by the Company, and
compliance with any applicable legal conditions or restrictions, the Company may withhold from fully vested shares of Common Stock otherwise issuable to you upon the exercise of your option a number of whole shares of Common Stock having a Fair
Market Value, determined by the Company as of the date of exercise, not in excess of the maximum amount of tax permitted to be withheld by law (or such lower amount as may be necessary to avoid classification of your option as a liability for
financial accounting purposes). 
 (c)        You may not exercise your
option unless the tax withholding obligations of the Company and/or any Affiliate are satisfied. Accordingly, you may not be able to exercise your option when desired even though your option is vested, and the Company will have no obligation to
issue a certificate for such shares of Common Stock or release such shares of Common Stock from any escrow provided for herein, if applicable, unless such obligations are satisfied. 

  
 5 














11.        TAX CONSEQUENCES.
You hereby agree that the Company does not have a duty to design or administer the Plan or its other compensation programs in a manner that minimizes your tax liabilities. You will not make any claim against the Company, or any of its Officers,
Directors, Employees or Affiliates related to tax liabilities arising from your option or your other compensation. In particular, you acknowledge that this option is exempt from Section 409A of the Code only if the exercise price per share
specified in the Grant Notice is at least equal to the “fair market value” per share of the Common Stock on the Date of Grant and there is no other impermissible deferral of compensation associated with the option. 

12.        NOTICES. Any notices provided for in your
option or the Plan will be given in writing (including electronically) and will be deemed effectively given upon receipt or, in the case of notices delivered by mail by the Company to you, five (5) days after deposit in the United States mail,
postage prepaid, addressed to you at the last address you provided to the Company. The Company may, in its sole discretion, decide to deliver any documents related to participation in the Plan and this option by electronic means or to request your
consent to participate in the Plan by electronic means. By accepting this option, you consent to receive such documents by electronic delivery and to participate in the Plan through an on-line or electronic
system established and maintained by the Company or another third party designated by the Company. 

13.        GOVERNING PLAN
DOCUMENT. Your option is subject to all the provisions of the Plan, the provisions of which are hereby made a part of your option, and is further subject to all interpretations, amendments, rules and regulations, which may from
time to time be promulgated and adopted pursuant to the Plan. If there is any conflict between the provisions of your option and those of the Plan, the provisions of the Plan will control. In addition, your option (and any compensation paid or
shares issued under your option) is subject to recoupment in accordance with The Dodd–Frank Wall Street Reform and Consumer Protection Act and any implementing regulations thereunder, any clawback policy adopted by the Company and any
compensation recovery policy otherwise required by applicable law. 

14.        OTHER DOCUMENTS. You hereby
acknowledge receipt of and the right to receive a document providing the information required by Rule 428(b)(1) promulgated under the Securities Act, which includes the Plan prospectus. In addition, you acknowledge receipt of the Company’s
policy permitting certain individuals to sell shares only during certain “window” periods and the Company’s insider trading policy, in effect from time to time. 

15.        EFFECT ON OTHER
EMPLOYEE BENEFIT PLANS. The value of this option will not be included as compensation, earnings, salaries, or other similar terms used when calculating your benefits under any employee benefit plan
sponsored by the Company or any Affiliate, except as such plan otherwise expressly provides. The Company expressly reserves its rights to amend, modify, or terminate any of the Company’s or any Affiliate’s employee benefit plans. 

16.        VOTING RIGHTS. You will not
have voting or any other rights as a stockholder of the Company with respect to the shares to be issued pursuant to this option until such shares are issued to you. Upon such issuance, you will obtain full voting and other rights as a stockholder of
the Company. Nothing contained in this option, and no action taken pursuant to its provisions, will create or be construed to create a trust of any kind or a fiduciary relationship between you and the Company or any other person. 

17.        SEVERABILITY. If all or any part of this
Option Agreement or the Plan is declared by any court or governmental authority to be unlawful or invalid, such unlawfulness or invalidity will not invalidate any portion of this Option Agreement or the Plan not declared to be unlawful or invalid.
Any Section of this Option Agreement (or part of such a Section) so declared to be unlawful or invalid shall, if 

  
 6 













 
possible, be construed in a manner which will give effect to the terms of such Section or part of a Section to the fullest extent possible while remaining lawful and valid. 

18.        MISCELLANEOUS. 

(a)        The rights and obligations of the Company under your option will be
transferable to any one or more persons or entities, and all covenants and agreements hereunder will inure to the benefit of, and be enforceable by the Company’s successors and assigns. 

(b)        You agree upon request to execute any further documents or
instruments necessary or desirable in the sole determination of the Company to carry out the purposes or intent of your option. 

(c)        You acknowledge and agree that you have reviewed your option in its
entirety, have had an opportunity to obtain the advice of counsel prior to executing and accepting your option, and fully understand all provisions of your option. 

(d)        This Option Agreement will be subject to all applicable laws,
rules, and regulations, and to such approvals by any governmental agencies or national securities exchanges as may be required. 

(e)        All obligations of the Company under the Plan and this Option
Agreement will be binding on any successor to the Company, whether the existence of such successor is the result of a direct or indirect purchase, merger, consolidation, or otherwise, of all or substantially all of the business and/or assets of the
Company. 
  

*        *        * 

This Option Agreement will be deemed to be signed by you upon the signing by you of the Stock Option Grant Notice to which it
is attached. 

  
 7 













 ATTACHMENT II 

2018 EQUITY INCENTIVE PLAN 

  
 1 













 ATTACHMENT III 

NOTICE OF EXERCISE 

 

			
	 SYNTHORX, INC.

11099 N. Torrey Pines Road, Suite 290        

La Jolla, California 92037
	  	  
 Date of Exercise: _______________


 This constitutes notice to Synthorx, Inc. (the “Company”) under my
stock option that I elect to purchase the below number of shares of Common Stock of the Company (the “Shares”) for the price set forth below. 
  

							
	Type of option:	  	Nonstatutory	 	  	 
	  
 Stock option dated:
	  			
		  	  
	  
	 
	  
 Number of Shares as
to which option is
exercised:
	  			
		  	  
	  
	 
	  
 Certificates to be
issued in name of:
	  			
		  	  
	  
	 
	  
 Total exercise price:
	  	$	______________	 
	  
 Cash payment delivered
herewith:
	  	$	______________	 
	  
 [Value of ________ Shares delivered herewith1:
	  	$	______________	] 
	  
 [Value of ________ Shares pursuant to net exercise2:
	  	$	______________	] 
	  
 [Regulation T Program (cashless exercise3):
	  	$	______________	] 

  
  

 
 1          Shares must meet the public trading requirements set forth in the option. Shares must be valued in accordance with the terms of the option
being exercised, and must be owned free and clear of any liens, claims, encumbrances or security interests. Certificates must be endorsed or accompanied by an executed assignment separate from certificate. 

2          The Company must have
established net exercise procedures at the time of exercise, in order to utilize this payment method. 
 3          Shares must meet the public trading requirements set forth in the option. 

  
 1 













 By this exercise, I agree (i) to provide such additional documents as
you may require pursuant to the terms of the Synthorx, Inc. 2018 Equity Incentive Plan and (ii) to provide for the payment by me to you (in the manner designated by you) of your withholding obligation, if any, relating to the exercise of this
option. 
 I further agree that, if required by the Company (or a representative of the underwriters) in connection with the
first underwritten registration of the offering of any securities of the Company under the Securities Act, I will not sell, dispose of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar
transaction with the same economic effect as a sale with respect to any shares of Common Stock or other securities of the Company for a period of one hundred eighty (180) days following the effective date of a registration statement of the
Company filed under the Securities Act (or such longer period as the underwriters or the Company shall request to facilitate compliance with FINRA Rule 2241 or any successor or similar rule or regulation) (the “Lock-Up Period”). I further agree to execute and deliver such other agreements as may be reasonably requested by the Company or the underwriters that are consistent with the foregoing 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 securities subject to the foregoing restrictions until
the end of such period. 
  
  

	
	 Very truly yours,
  

 




  
 2 













 SYNTHORX, INC. 

RESTRICTED STOCK UNIT GRANT NOTICE 

(2018 EQUITY INCENTIVE PLAN) 

Synthorx, Inc. (the “Company”), pursuant to its 2018 Equity Incentive Plan (the “Plan”),
hereby awards to Participant a Restricted Stock Unit Award for the number of shares of the Company’s Common Stock (“Restricted Stock Units”) set forth below (the “Award”). The Award is subject to
all of the terms and conditions as set forth in this notice of grant (this “Restricted Stock Unit Grant Notice”), and in the Plan and the Restricted Stock Unit Award Agreement (the “Award Agreement”),
both of which are attached hereto and incorporated herein in their entirety. Capitalized terms not explicitly defined herein shall have the meanings set forth in the Plan or the Award Agreement. In the event of any conflict between the terms in this
Restricted Stock Unit Grant Notice or the Award Agreement and the Plan, the terms of the Plan shall control. 
  

					
	 Participant:
	 	  
	 	
	 Date of Grant:
	 	  
	 	
	 Vesting Commencement Date:
	 	  
	 	
	 Number of Restricted Stock Units:
	 	  
	 	

  

			
	Vesting Schedule:	  	 [The Restricted Stock Units subject to this Award shall vest in a series of three successive equal annual installments over
the three-year period measured from the Vesting Commencement Date], subject to Participant’s Continuous Service through each such vesting date and the potential vesting acceleration described in Section 2 of the Award
Agreement.

		
	Issuance Schedule:	  	 Subject to any Capitalization Adjustment, one share of Common Stock (or its cash equivalent, at the discretion of the
Company) will be issued for each Restricted Stock Unit that vests at the time set forth in Section 6 of the Award Agreement.


 Additional Terms/Acknowledgements: Participant acknowledges receipt of, and understands and agrees to,
this Restricted Stock Unit Grant Notice, the Award Agreement and the Plan. Participant acknowledges and agrees that this Restricted Stock Unit Grant Notice and the Award Agreement may not be modified, amended, or revised except as provided in the
Plan. Participant further acknowledges that as of the Date of Grant, this Restricted Stock Unit Grant Notice, the Award Agreement and the Plan set forth the entire understanding between Participant and the Company regarding the acquisition of the
Common Stock pursuant to the Award specified above and supersede all prior oral and written agreements on the terms of this Award, with the exception, if applicable, of (i) equity awards previously granted and delivered to Participant,
(ii) any compensation recovery policy that is adopted by the Company or is otherwise required by applicable law and (iii) any written employment or severance arrangement or other written agreement entered into between the Company and
Participant specifying the terms that should govern this Award upon the terms and conditions set forth therein. 

  
 1 













 By accepting this Award, Participant acknowledges having received and read the Restricted
Stock Unit Grant Notice, the Award Agreement and the Plan and agrees to all of the terms and conditions set forth in these documents. Participant consents to receive Plan and related documents by electronic delivery and to participate in the Plan
through an on-line or electronic system established and maintained by the Company or another third party designated by the Company. 
  

					
	 SYNTHORX, INC.
  

By:                       
                                         
                                         
      
 Signature
  

Title:                      
                                         
                                         
    
  

Date:                      
                                         
                                         
    
	  	 
 

            
	  	 PARTICIPANT
  

 
  

Signature
  

Date:                      
                                         
                                       



 ATTACHMENTS: Award Agreement and 2018 Equity Incentive Plan 

  
 2 













 ATTACHMENT I 

SYNTHORX, INC. 

2018 EQUITY INCENTIVE PLAN 

RESTRICTED STOCK UNIT AWARD AGREEMENT 

Pursuant to the Restricted Stock Unit Grant Notice (the “Grant Notice”) and this Restricted Stock Unit
Award Agreement (the “Agreement”), Synthorx, Inc. (the “Company”) has awarded you (“Participant”) a Restricted Stock Unit Award (the “Award”) pursuant to
the Company’s 2018 Equity Incentive Plan (the “Plan”) for the number of Restricted Stock Units/shares indicated in the Grant Notice. Capitalized terms not explicitly defined in this Agreement or the Grant Notice shall
have the same meanings given to them in the Plan. The terms of your Award, in addition to those set forth in the Grant Notice, are as follows. 

1.        GRANT OF THE
AWARD. This Award represents the right to be issued on a future date one (1) share of Common Stock for each Restricted Stock Unit that vests on the applicable vesting date(s) (subject to any adjustment under Section 3
below) as indicated in the Grant Notice. As of the Date of Grant, the Company will credit to a bookkeeping account maintained by the Company for your benefit (the “Account”) the number of Restricted Stock Units/shares of
Common Stock subject to the Award. Notwithstanding the foregoing, the Company reserves the right to issue you the cash equivalent of Common Stock, in part or in full satisfaction of the delivery of Common Stock in connection with the vesting of the
Restricted Stock Units, and, to the extent applicable, references in this Agreement and the Grant Notice to Common Stock issuable in connection with your Restricted Stock Units will include the potential issuance of its cash equivalent pursuant to
such right. This Award was granted in consideration of your services to the Company. 

2.        VESTING. Subject to the limitations contained
herein, your Award will vest, if at all, in accordance with the vesting schedule provided in the Grant Notice. Vesting will cease upon the termination of your Continuous Service and the Restricted Stock Units credited to the Account that were not
vested on the date of such termination will be forfeited at no cost to the Company and you will have no further right, title or interest in or to such Award or the shares of Common Stock to be issued in respect of such portion of the Award. 

(a) In the event of a Change in Control in which the surviving corporation or acquiring corporation (or its parent
company) assumes or continues your Award or substitutes a similar stock award for such Award, then the portion of your Award that has not vested as of the effective time of such Change in Control shall continue to vest according to the vesting
schedule in your Grant Notice; provided that such portion of your Award shall vest no less favorably than quarterly over the twelve (12) month period following the Change in Control. Notwithstanding the foregoing, if a Change in Control occurs
and within three (3) months prior to, or within twelve (12) months after, the effective time of such Change in Control, your Continuous Service terminates due to an involuntary termination (not including death or Disability) without Cause
or due to your voluntary termination with Good Reason, then, as of the date of termination of Continuous Service, the vesting of your Award will be accelerated in full. 

(b) “Good Reason” means the occurrence of any of the following events, conditions or actions
taken by the Company without your written consent: (i) a material reduction of your annual base salary; provided, however, that Good Reason shall not be deemed to have occurred in the event of a reduction in your annual base salary that
is pursuant to a salary reduction program affecting substantially all of the similarly situated employees of the Company and that does not adversely affect you to a greater extent than other similarly situated employees; (ii) a material
reduction in your authority, duties or 

  
 3 













 
responsibilities; (iii) a relocation of your principal place of employment with the Company to a place that increases your one-way commute by more
than fifty (50) miles as compared to your then-current principal place of employment immediately prior to such relocation (excluding regular travel in the ordinary course of business); (iv) in the case of employees reporting to the Board or the
Company’s Chief Executive Officer, a material adverse change in such reporting level requiring you to report to a corporate officer or executive other than the Board or the Company’s Chief Executive Officer, as the case may be; or
(v) a material breach by the Company of any material agreement between you and the Company; provided, however, that in each case above, in order for your resignation to be deemed to have been for Good Reason, you must first give the
Board written notice of the action or omission giving rise to “Good Reason” within ninety (90) days after the first occurrence thereof; the Company must fail to reasonably cure such action or omission within thirty (30) days
after receipt of such notice (the “Cure Period”), and your resignation from all positions you hold with the Company must be effective not later than thirty (30) days after the expiration of such Cure Period. 

(c)        If any payment or benefit you would receive from the Company or
otherwise in connection with a Change in Control or other similar transaction (a “280G Payment”) would (i) constitute a “parachute payment” within the meaning of Section 280G of the Code, and (ii) but
for this sentence, be subject to the excise tax imposed by Section 4999 of the Code (the “Excise Tax”), then any such 280G Payment (a “Payment”) shall be equal to the Reduced Amount. The
“Reduced Amount” shall be either (x) the largest portion of the Payment that would result in no portion of the Payment (after reduction) being subject to the Excise Tax or (y) the largest portion, up to and
including the total, of the Payment, whichever amount (i.e., the amount determined by clause (x) or by clause (y)), after taking into account all applicable federal, state and local employment taxes, income taxes, and the Excise Tax (all
computed at the highest applicable marginal rate), results in your receipt, on an after-tax basis, of the greater economic benefit notwithstanding that all or some portion of the Payment may be subject to the
Excise Tax. If a reduction in a Payment is required pursuant to the preceding sentence and the Reduced Amount is determined pursuant to clause (x) of the preceding sentence, the reduction shall occur in the manner (the “Reduction
Method”) that results in the greatest economic benefit for you. If more than one method of reduction will result in the same economic benefit, the items so reduced will be reduced pro rata (the “Pro Rata Reduction
Method”). 
 Notwithstanding the foregoing, if the Reduction Method or the Pro Rata Reduction Method would
result in any portion of the Payment being subject to taxes pursuant to Section 409A of the Code that would not otherwise be subject to taxes pursuant to Section 409A of the Code, then the Reduction Method and/or the Pro Rata Reduction
Method, as the case may be, shall be modified so as to avoid the imposition of taxes pursuant to Section 409A of the Code as follows: (A) as a first priority, the modification shall preserve to the greatest extent possible, the greatest
economic benefit for you as determined on an after-tax basis; (B) as a second priority, Payments that are contingent on future events (e.g., being terminated without cause), shall be reduced (or
eliminated) before Payments that are not contingent on future events; and (C) as a third priority, Payments that are “deferred compensation” within the meaning of Section 409A of the Code shall be reduced (or eliminated) before
Payments that are not deferred compensation within the meaning of Section 409A of the Code. 
 Unless you and the
Company agree on an alternative accounting firm, at the Company’s election, either (i) Ernst & Young LLP or (ii) the accounting firm engaged by the Company for general tax compliance purposes as of the day prior to the
effective date of the change of control transaction triggering the Payment shall perform the foregoing calculations. If the accounting firm so engaged by the Company is serving as accountant or auditor for the individual, entity or group effecting
the change of control transaction, the Company shall appoint a nationally recognized accounting firm to make the determinations required hereunder. The Company shall bear all expenses with respect to the determinations by such accounting firm
required to be made hereunder. The Company shall use 

  
 4 













 
commercially reasonable efforts to cause the accounting firm engaged to make the determinations hereunder to provide its calculations, together with detailed supporting documentation, to you and
the Company within fifteen (15) calendar days after the date on which your right to a 280G Payment becomes reasonably likely to occur (if requested at that time by you or the Company) or such other time as requested by you or the Company. 

If you receive a Payment for which the Reduced Amount was determined pursuant to clause (x) of the first paragraph of
this Section 2(c) and the Internal Revenue Service determines thereafter that some portion of the Payment is subject to the Excise Tax, you shall promptly return to the Company a sufficient amount of the Payment (after reduction pursuant to
clause (x) of the first paragraph of this Section 2(c) so that no portion of the remaining Payment is subject to the Excise Tax. For the avoidance of doubt, if the Reduced Amount was determined pursuant to clause (y) in the first
paragraph of this Section 2(c), you shall have no obligation to return any portion of the Payment pursuant to the preceding sentence. 

3.        NUMBER OF SHARES.
The number of Restricted Stock Units subject to your Award may be adjusted from time to time for Capitalization Adjustments, as provided in the Plan. Any additional Restricted Stock Units, shares, cash or other property that becomes subject to
the Award pursuant to this Section 3, if any, shall be subject, in a manner determined by the Board, to the same forfeiture restrictions, restrictions on transferability, and time and manner of delivery as applicable to the other Restricted
Stock Units and shares covered by your Award. Notwithstanding the provisions of this Section 3, no fractional shares or rights for fractional shares of Common Stock shall be created pursuant to this Section 3. Any fraction of a share will
be rounded down to the nearest whole share. 

4.        SECURITIES LAW
COMPLIANCE. You may not be issued any Common Stock under your Award unless the shares of Common Stock underlying the Restricted Stock Units are either (i) then registered under the Securities Act, or
(ii) the Company has determined that such issuance would be exempt from the registration requirements of the Securities Act. Your Award must also comply with other applicable laws and regulations governing the Award, and you shall not receive
such Common Stock if the Company determines that such receipt would not be in material compliance with such laws and regulations. 

5.        TRANSFER
RESTRICTIONS. Prior to the time that shares of Common Stock have been delivered to you, you may not transfer, pledge, sell or otherwise dispose of this Award or the shares issuable in respect of your Award, except
as expressly provided in this Section 5. For example, you may not use shares that may be issued in respect of your Restricted Stock Units as security for a loan. The restrictions on transfer set forth herein will lapse upon delivery to you of
shares in respect of your vested Restricted Stock Units. 
 (a) Death. Your Award is transferable by will and by the
laws of descent and distribution. At your death, vesting of your Award will cease and your executor or administrator of your estate shall be entitled to receive, on behalf of your estate, any Common Stock or other consideration that vested but was
not issued before your death. 
 (b) Domestic Relations Orders. Upon receiving written permission from the Board or
its duly authorized designee, and provided that you and the designated transferee enter into transfer and other agreements required by the Company, you may transfer your right to receive the distribution of Common Stock or other consideration
hereunder, pursuant to a domestic relations order, marital settlement agreement or other divorce or separation instrument as permitted by applicable law that contains the information required by the Company to effectuate the transfer. You are
encouraged to discuss the proposed terms of any division of this Award with the Company General Counsel prior to 

  
 5 













 
finalizing the domestic relations order or marital settlement agreement to verify that you may make such transfer, and if so, to help ensure the required information is contained within the
domestic relations order or marital settlement agreement. 

6.        DATE OF ISSUANCE.  

(a)        The issuance of shares in respect of the Restricted Stock Units is
intended to comply with Treasury Regulations Section 1.409A-1(b)(4) and will be construed and administered in such a manner. Subject to the satisfaction of the Withholding Obligation set forth in
Section 11 of this Agreement, in the event one or more Restricted Stock Units vests, the Company shall issue to you one (1) share of Common Stock for each Restricted Stock Unit that vests on the applicable vesting date(s) (subject to any
adjustment under Section 3 above). Each issuance date determined by this paragraph is referred to as an “Original Issuance Date”. 

(b)        If the Original Issuance Date falls on a date that is not a
business day, delivery shall instead occur on the next following business day. In addition, if: 

(i)        the Original Issuance Date does not occur (1) during an
“open window period” applicable to you, as determined by the Company in accordance with the Company’s then-effective policy on trading in Company securities, or (2) on a date when you are otherwise permitted to sell shares of
Common Stock on an established stock exchange or stock market (including but not limited to under a previously established written trading plan that meets the requirements of Rule 10b5-1 under the Exchange Act
and was entered into in compliance with the Company’s policies (a “10b5-1 Arrangement”)), and 

(ii)        either (1) a Withholding Obligation does not apply, or
(2) the Company decides, prior to the Original Issuance Date, (A) not to satisfy the Withholding Obligation by withholding shares of Common Stock from the shares otherwise due, on the Original Issuance Date, to you under this Award, and
(B) not to permit you to enter into a “same day sale” commitment with a broker-dealer pursuant to Section 11 of this Agreement (including but not limited to a commitment under a 10b5-1
Arrangement) and (C) not to permit you to pay your Withholding Obligation in cash, 
 then the shares that would
otherwise be issued to you on the Original Issuance Date will not be delivered on such Original Issuance Date and will instead be delivered on the first business day when you are not prohibited from selling shares of the Company’s Common Stock
in the open public market, but in no event later than December 31 of the calendar year in which the Original Issuance Date occurs (that is, the last day of your taxable year in which the Original Issuance Date occurs), or, if and only if
permitted in a manner that complies with Treasury Regulations Section 1.409A-1(b)(4), no later than the date that is the 15th day of the third calendar month of the applicable year following the year in
which the shares of Common Stock under this Award are no longer subject to a “substantial risk of forfeiture” within the meaning of Treasury Regulations Section 1.409A-1(d). 

(c)        The form of delivery (e.g., a stock certificate or
electronic entry evidencing such shares) shall be determined by the Company. 

7.        DIVIDENDS. You shall receive no benefit or
adjustment to your Award with respect to any cash dividend, stock dividend or other distribution that does not result from a Capitalization Adjustment; provided, however, that this sentence will not apply with respect to any shares of Common Stock
that are delivered to you in connection with your Award after such shares have been delivered to you. 

  
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8.        RESTRICTIVE LEGENDS. The shares
of Common Stock issued in respect of your Award shall be endorsed with appropriate legends as determined by the Company. 

9.        EXECUTION OF
DOCUMENTS. You hereby acknowledge and agree that the manner selected by the Company by which you indicate your consent to your Grant Notice is also deemed to be your execution of your Grant Notice and of this Agreement. You
further agree that such manner of indicating consent may be relied upon as your signature for establishing your execution of any documents to be executed in the future in connection with your Award. 

10.        AWARD NOT A
SERVICE CONTRACT. 

(a)        Nothing in this Agreement (including, but not limited to, the
vesting of your Award or the issuance of the shares in respect of your Award), the Plan or any covenant of good faith and fair dealing that may be found implicit in this Agreement or the Plan shall: (i) confer upon you any right to continue in
the employ or service of, or affiliation with, the Company or an Affiliate; (ii) constitute any promise or commitment by the Company or an Affiliate regarding the fact or nature of future positions, future work assignments, future compensation
or any other term or condition of employment or affiliation; (iii) confer any right or benefit under this Agreement or the Plan unless such right or benefit has specifically accrued under the terms of this Agreement or Plan; or
(iv) deprive the Company of the right to terminate you at will and without regard to any future vesting opportunity that you may have. 

(b)        By accepting this Award, you acknowledge and agree that the right
to continue vesting in the Award pursuant to the vesting schedule provided in the Grant Notice may not be earned unless (in addition to any other conditions described in the Grant Notice and this Agreement) you continue as an employee, director or
consultant at the will of the Company and affiliate, as applicable (not through the act of being hired, being granted this Award or any other award or benefit) and that the Company has the right to reorganize, sell,
spin-out or otherwise restructure one or more of its businesses or Affiliates at any time or from time to time, as it deems appropriate (a “reorganization”). You acknowledge and agree
that such a reorganization could result in the termination of your Continuous Service, or the termination of Affiliate status of your employer and the loss of benefits available to you under this Agreement, including but not limited to, the
termination of the right to continue vesting in the Award. You further acknowledge and agree that this Agreement, the Plan, the transactions contemplated hereunder and the vesting schedule set forth herein or any covenant of good faith and fair
dealing that may be found implicit in any of them do not constitute an express or implied promise of continued engagement as an employee or consultant for the term of this Agreement, for any period, or at all, and shall not interfere in any way with
the Company’s right to terminate your Continuous Service at any time, with or without your cause or notice, or to conduct a reorganization. 

11.        WITHHOLDING OBLIGATION. 

(a)        On each vesting date, and on or before the time you receive a distribution
of the shares of Common Stock in respect of your Restricted Stock Units, and at any other time as reasonably requested by the Company in accordance with applicable tax laws, you hereby authorize any required withholding from the Common Stock
issuable to you and/or otherwise agree to make adequate provision, including in cash, for any sums required to satisfy the federal, state, local and foreign tax withholding obligations of the Company or any Affiliate that arise in connection with
your Award (the “Withholding Obligation”). 
 (b)        By
accepting this Award, you acknowledge and agree that the Company or any Affiliate may, in its sole discretion, satisfy all or any portion of the Withholding Obligation relating to your Restricted Stock Units by any of the following means or by a
combination of such means: (i) 

  
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causing you to pay any portion of the Withholding Obligation in cash; (ii) withholding from any compensation otherwise payable to you by the Company; (iii) withholding shares of Common
Stock from the shares of Common Stock issued or otherwise issuable to you in connection with the Award with a Fair Market Value (measured as of the date shares of Common Stock are issued pursuant to Section 6) equal to the amount of such
Withholding Obligation; provided, however, that the number of such shares of Common Stock so withheld will not exceed the amount necessary to satisfy the Withholding Obligation using the maximum statutory withholding rates for federal, state, local
and foreign tax purposes, including payroll taxes, that are applicable to supplemental taxable income; and provided, further, that to the extent necessary to qualify for an exemption from application of Section 16(b) of the Exchange Act,
if applicable, such share withholding procedure will be subject to the express prior approval of the Board or the Company’s Compensation Committee; and/or (iv) permitting or requiring you to enter into a “same day sale”
commitment, if applicable, with a broker-dealer that is a member of the Financial Industry Regulatory Authority (a “FINRA Dealer”), pursuant to this authorization and without further consent, whereby you irrevocably elect to
sell a portion of the shares to be delivered in connection with your Restricted Stock Units to satisfy the Withholding Obligation and whereby the FINRA Dealer irrevocably commits to forward the proceeds necessary to satisfy the Withholding
Obligation directly to the Company and/or its Affiliates. Unless the Withholding Obligation is satisfied, the Company shall have no obligation to deliver to you any Common Stock or any other consideration pursuant to this Award. 

(c)        In the event the Withholding Obligation arises prior to the delivery to
you of Common Stock or it is determined after the delivery of Common Stock to you that the amount of the Withholding Obligation was greater than the amount withheld by the Company, you agree to indemnify and hold the Company harmless from any
failure by the Company to withhold the proper amount. 

12.        TAX CONSEQUENCES. The Company
has no duty or obligation to minimize the tax consequences to you of this Award and shall not be liable to you for any adverse tax consequences to you arising in connection with this Award. You are hereby advised to consult with your own personal
tax, financial and/or legal advisors regarding the tax consequences of this Award and by signing the Grant Notice, you have agreed that you have done so or knowingly and voluntarily declined to do so. You understand that you (and not the Company)
shall be responsible for your own tax liability that may arise as a result of this investment or the transactions contemplated by this Agreement. 

13.        
LOCK-UP PERIOD. By accepting your Award, you agree that you will not sell, dispose of, transfer, make any short sale of, grant any option for
the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale with respect to any shares of Common Stock or other securities of the Company held by you, for a period of one hundred eighty (180) days
following the effective date of a registration statement of the Company filed under the Securities Act or such longer period as the underwriters or the Company will request to facilitate compliance with FINRA Rule 2241 or any successor or similar
rules or regulation (the “Lock-Up Period”); provided, however, that nothing contained in this section will prevent the exercise of a repurchase option, if any, in favor of the
Company during the Lock-Up Period. You further agree to execute and deliver such other agreements as may be reasonably requested by the Company or the underwriters that are consistent with the foregoing 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 your shares of Common Stock until the end of such period. You also agree that any
transferee of any shares of Common Stock (or other securities) of the Company held by you will be bound by this Section 13. The underwriters of the Company’s stock are intended third party beneficiaries of this Section 13 and will
have the right, power and authority to enforce the provisions hereof as though they were a party hereto. 

14.        UNSECURED OBLIGATION. Your
Award is unfunded, and as a holder of a vested Award, you shall be considered an unsecured creditor of the Company with respect to the Company’s obligation, 

  
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if any, to issue shares or other property pursuant to this Agreement. You shall not have voting or any other rights as a stockholder of the Company with respect to the shares to be issued
pursuant to this Agreement until such shares are issued to you pursuant to Section 6 of this Agreement. Upon such issuance, you will obtain full voting and other rights as a stockholder of the Company. Nothing contained in this Agreement, and
no action taken pursuant to its provisions, shall create or be construed to create a trust of any kind or a fiduciary relationship between you and the Company or any other person. 

15.        NOTICES. Any notice or request
required or permitted hereunder shall be given in writing (including electronically) and will be deemed effectively given upon receipt or, in the case of notices delivered by mail by the Company to you, five (5) days after deposit in the United
States mail, postage prepaid, addressed to you at the last address you provided to the Company. The Company may, in its sole discretion, decide to deliver any documents related to participation in the Plan and this Award by electronic means or to
request your consent to participate in the Plan by electronic means. By accepting this Award, you consent to receive such documents by electronic delivery and to participate in the Plan through an on-line or
electronic system established and maintained by the Company or another third party designated by the Company. 

16.        HEADINGS. The headings of the
Sections in this Agreement are inserted for convenience only and shall not be deemed to constitute a part of this Agreement or to affect the meaning of this Agreement. 

17.        MISCELLANEOUS. 

(a)        The rights and obligations of the Company under your Award shall be
transferable by the Company to any one or more persons or entities, and all covenants and agreements hereunder shall inure to the benefit of, and be enforceable by, the Company’s successors and assigns. 

(b)        You agree upon request to execute any further documents or
instruments necessary or desirable in the sole determination of the Company to carry out the purposes or intent of your Award. 

(c)        You acknowledge and agree that you have reviewed your Award in its
entirety, have had an opportunity to obtain the advice of counsel prior to executing and accepting your Award and fully understand all provisions of your Award. 

(d)        This Agreement shall be subject to all applicable laws, rules, and
regulations, and to such approvals by any governmental agencies or national securities exchanges as may be required. 

(e)        All obligations of the Company under the Plan and this Agreement
shall be binding on any successor to the Company, whether the existence of such successor is the result of a direct or indirect purchase, merger, consolidation, or otherwise, of all or substantially all of the business and/or assets of the Company.

 18.        GOVERNING PLAN
DOCUMENT. Your Award is subject to all the provisions of the Plan, the provisions of which are hereby made a part of your Award, and is further subject to all interpretations, amendments, rules and regulations which
may from time to time be promulgated and adopted pursuant to the Plan. Your Award (and any compensation paid or shares issued under your Award) is subject to recoupment in accordance with The Dodd–Frank Wall Street Reform and Consumer
Protection Act and any implementing regulations thereunder, any clawback policy adopted by the Company and any compensation recovery policy otherwise required by applicable law. No recovery of compensation under such a clawback policy will be an
event giving rise to a right to voluntarily terminate employment upon a 

  
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resignation for “good reason,” or for a “constructive termination” or any similar term under any plan of or agreement with the Company. 

19.        EFFECT ON OTHER
EMPLOYEE BENEFIT PLANS. The value of the Award subject to this Agreement shall not be included as compensation, earnings, salaries, or other similar terms used when calculating benefits under any
employee benefit plan (other than the Plan) sponsored by the Company or any Affiliate except as such plan otherwise expressly provides. The Company expressly reserves its rights to amend, modify, or terminate any or all of the employee benefit plans
of the Company or any Affiliate. 

20.        SEVERABILITY. If all or any
part of this Agreement or the Plan is declared by any court or governmental authority to be unlawful or invalid, such unlawfulness or invalidity shall not invalidate any portion of this Agreement or the Plan not declared to be unlawful or invalid.
Any Section of this Agreement (or part of such a Section) so declared to be unlawful or invalid shall, if possible, be construed in a manner which will give effect to the terms of such Section or part of a Section to the fullest extent possible
while remaining lawful and valid. 
 21.        OTHER
DOCUMENTS. You hereby acknowledge receipt or the right to receive a document providing the information required by Rule 428(b)(1) promulgated under the Securities Act. In addition, you acknowledge receipt of the
Company’s policy permitting certain individuals to sell shares only during certain “window” periods and the Company’s insider trading policy, in effect from time to time. 

22.        AMENDMENT. This Agreement may not be modified,
amended or terminated except by an instrument in writing, signed by you and by a duly authorized representative of the Company. Notwithstanding the foregoing, this Agreement may be amended solely by the Board by a writing which specifically states
that it is amending this Agreement, so long as a copy of such amendment is delivered to you, and provided that, except as otherwise expressly provided in the Plan, no such amendment materially adversely affecting your rights hereunder may be made
without your written consent. Without limiting the foregoing, the Board reserves the right to change, by written notice to you, the provisions of this Agreement in any way it may deem necessary or advisable to carry out the purpose of the Award as a
result of any change in applicable laws or regulations or any future law, regulation, ruling, or judicial decision, provided that any such change shall be applicable only to rights relating to that portion of the Award which is then subject to
restrictions as provided herein. 
 23.        COMPLIANCE
WITH SECTION 409A OF THE CODE. This Award is intended to be exempt from the application of
Section 409A of the Code, including but not limited to by reason of complying with the “short-term deferral” rule set forth in Treasury Regulation Section 1.409A-1(b)(4) and any ambiguities
herein shall be interpreted accordingly. Notwithstanding the foregoing, if it is determined that the Award fails to satisfy the requirements of the short-term deferral rule and is otherwise not exempt from, and determined to be deferred compensation
subject to Section 409A of the Code, this Award shall comply with Section 409A to the extent necessary to avoid adverse personal tax consequences and any ambiguities herein shall be interpreted accordingly. If it is determined that the
Award is deferred compensation subject to Section 409A and you are a “Specified Employee” (within the meaning set forth in Section 409A(a)(2)(B)(i) of the Code) as of the date of your “Separation from Service” (as
defined in Section 409A), then the issuance of any shares that would otherwise be made upon the date of your Separation from Service or within the first six (6) months thereafter will not be made on the originally scheduled date(s) and
will instead be issued in a lump sum on the date that is six (6) months and one day after the date of the Separation from Service, with the balance of the shares issued thereafter in accordance with the original vesting and issuance schedule
set forth above, but if and only if such delay in the issuance of the shares is necessary to avoid the imposition of adverse taxation on you in respect of 

  
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the shares under Section 409A of the Code. Each installment of shares that vests is intended to constitute a “separate payment” for purposes of Treasury Regulation Section 1.409A-2(b)(2).  
 * * * * * 

This Restricted Stock Unit Award Agreement shall be deemed to be signed by the Company and the Participant upon the signing by
the Participant of the Restricted Stock Unit Grant Notice to which it is attached. 

  
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 ATTACHMENT II 

2018 EQUITY INCENTIVE PLAN 

  
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