Document:

EX-10.3

 Exhibit 10.3 

AMBRX, INC. 
 2013 EQUITY
INCENTIVE PLAN 
 1. Purpose.  

The purpose of the Plan is to advance the interests of the Company’s stockholders by enhancing the Company’s ability to encourage
ownership of shares by Employees, Directors and Consultants of the Company in order to attract, retain, incentivize and reward such persons who make (or are expected to make) important contributions to the Company, and thereby better aligning the
interests of such persons with those of the Company’s stockholders. Capitalized terms used in the Plan are defined in Section 2 below. 

2. Definitions. As used in the plan, the following words and phrases shall have the following meanings: 

(a) “Administrator” means the Board or a Committee to the extent that the Board’s powers or authority under the
Plan have been delegated to such Committee. The term “Administrator” also shall refer to such person(s) to whom the Board or Committee has delegated authority pursuant to Section 4(c), unless the Board or Committee has revoked such
delegation or has again assumed such authority. 
 (b) “Applicable Laws” means the requirements relating to the
administration of equity incentive plans under U.S. federal and state securities, tax and other applicable laws, rules and regulations, the applicable rules of any stock exchange or quotation system on which the Common Stock is listed or quoted and
the applicable laws and rules of any foreign country or other jurisdiction where Awards are granted or issued under the Plan. 
 (c)
“Award” means, individually or collectively, a grant under the Plan of Options (Incentive Stock Options and Nonstatutory Stock Options), Restricted Stock, Restricted Stock Units or Other Stock-Based Awards. 

(d) “Award Agreement” means a written agreement evidencing an Award, which agreements may be in electronic
medium and shall contain such terms and conditions with respect to an Award as the Administrator shall determine, consistent with and subject to the terms and conditions of the Plan. 

(e) “Board” means the Board of Directors of the Company. 

(f) “Change in Control” means an Ownership Change Event or a series of related Ownership Change Events (collectively,
a “Transaction”) wherein the stockholders of the Company immediately before the Transaction do not retain immediately after the Transaction, in substantially the same proportions as their ownership of shares of the
Company’s voting stock immediately before the Transaction, direct or indirect beneficial ownership of more than fifty percent (50%) of the total combined voting power of the outstanding voting securities of the Company or, in the case of a
sale, exchange or transfer or all or substantially all of the assets of the Company, the corporation or other business entity to which the assets of the Company were transferred (the “Transferee”), as the case may be. For
purposes of the preceding sentence, indirect beneficial ownership shall include, without limitation, an interest resulting from ownership of the voting securities of one or more corporations or other business entities which own the Company or the
Transferee, as the case may be, either directly or through one or more subsidiary corporations or other business entities. The Administrator shall have the right to determine whether multiple sales or exchanges of the voting securities of the
Company or multiple Ownership Change Events are related, and its determination shall be final, binding and conclusive. 

  
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 (g) “Code” means the Internal Revenue Code of 1986, as amended,
and the regulations issued thereunder. 
 (h) “Committee” means the Compensation Committee or other committee
or subcommittee of the Board duly appointed to administer the Plan and having such powers specified by the Board, which may be comprised of one or more directors and/or executive officers of the Company, in either case, to the extent permitted in
accordance with Applicable Laws. 
 (i) “Common Stock” means the common stock of the Company. 

(j) “Company” means Ambrx, Inc., a Delaware corporation, or any successor thereto. Except where the context
otherwise requires, the term “Company” includes any of the Company’s present or future parent or subsidiary corporations as defined in Sections 424(e) or (f) of the Code and any other business venture (including, without
limitation, joint venture or limited liability company) in which the Company has a significant interest, as determined by the Administrator. 

(k) “Consultant” means any person, including any advisor, engaged by the Company or a parent or
subsidiary of the Company to render services to such entity if: (i) the consultant or adviser renders bona fide services to the Company; (ii) the services rendered by the consultant or advisor are not in connection with the offer or
sale of securities in a capital-raising transaction and do not directly or indirectly promote or maintain a market for the Company’s securities; and (iii) the consultant or advisor is a natural person, or such other advisor or consultant
as is approved by the Administrator. 
 (l) “Designated Beneficiary” means the beneficiary or
beneficiaries designated, in a manner determined by the Administrator, by a Participant to receive amounts due or exercise rights of the Participant in the event of the Participant’s death or incapacity In the absence of an effective
designation by a Participant, “Designated Beneficiary” shall mean the Participant’s estate. 
 (m)
“Director” means a member of the Board. 
 (n) “Disability” means a permanent
and total disability within the meaning of Section 22(e)(3) of the Code, as it may be amended from time to time. 
 (o)
“Dividend Equivalents” means a right granted to a Participant pursuant to Section 7(d)(3) hereof to receive the equivalent value (in cash or shares of Common Stock) of dividends paid on shares of Common Stock.

 (p) “Employee” means any person employed by the Company (within the meaning of Section 3401(c) of the Code)
or any parent or subsidiary of the Company. The Company shall determine in good faith and in the exercise of its discretion whether an individual has become or has ceased to be an Employee and the effective date of such individual’s employment
or termination of employment, as the case may be. For purposes of an individual’s rights, if any, under the Plan as of the time of the Company’s determination, all such determinations by the Company shall be final, binding and conclusive,
notwithstanding that the Company or any court of law or governmental agency subsequently makes a contrary determination. 

  
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 (q) “Equity Restructuring” means, as determined by the
Administrator, a non-reciprocal transaction between the Company and its stockholders, such as a stock dividend, stock split, spin-off or recapitalization through a large, nonrecurring cash dividend, that affects the shares of Common Stock (or other
securities of the Company) or the share price of Common Stock (or other securities of the Company) and causes a change in the per share value of the Common Stock underlying outstanding Awards. 

(r) “Exchange Act” means the Securities Exchange Act of 1934, as amended. 

(s) “Fair Market Value” means, as of any date, the value of Stock determined as follows: (i) if the Common
Stock is listed on any established stock exchange, its Fair Market Value shall be the closing sales price for such Common Stock as quoted on such exchange for such date, or if no sale occurred on such date, the first market trading day immediately
prior to such date during which a sale occurred, as reported in The Wall Street Journal or such other source as the Administrator deems reliable; (ii) if the Common Stock is not traded on a stock exchange but is quoted on a national
market or other quotation system, the last sales price on such date, or if no sales occurred on such date, then on the date immediately prior to such date on which sales prices are reported, as reported in The Wall Street Journal or such
other source as the Administrator deems reliable; or (iii) in the absence of an established market for the Common Stock, the Fair Market Value thereof shall be determined by the Board. 

(t) “Incentive Stock Option” means an “incentive stock option” as defined in Section 422 of the
Code. 
 (u) “Nonstatutory Stock Option” means an Option that is not intended to be or otherwise does
not qualify as an Incentive Stock Option. 
 (v) “Option” means an option to purchase Common Stock pursuant
to this Plan and includes only Incentive Stock Options and Nonstatutory Stock Options. 
 (w) “Other Stock-Based
Awards” means other Awards of shares of Common Stock, and other Awards that are valued in whole or in part by reference to, or are otherwise based on, shares of Common Stock or other property. 

(x) “Ownership Change Event” means the occurrence of one or more of the following with respect to the Company:
(i) the direct or indirect sale or exchange in a single or series of related transactions by the stockholders of the Company of more than fifty percent (50%) of the voting stock of the Company; (ii) a merger or consolidation in which
the Company is a party; (iii) the sale, exchange, or transfer of all or substantially all of the assets of the Company; or (iv) a liquidation or dissolution of the Company. 

(y) “Participant” means a Service Provider who has been granted an Award under the Plan (or, if
applicable, the Service Provider’s estate or legal representative if the Award has been assigned or transferred as permitted hereunder). 

(z) “Plan” means this Ambrx, Inc. 2013 Equity Incentive Plan, as amended from time to time. 

(aa) “Prior Plan” means the Ambrx, Inc. 2003 Stock Option Plan, as amended from time to time. 

  
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 (bb) “Publicly Listed Company” means that the Company or its successor
(i) is required to file periodic reports pursuant to Section 12 of the Exchange Act and (ii) the Common Stock is listed on one or more National Securities Exchanges (within the meaning of the Exchange Act) or is quoted on NASDAQ or a
successor quotation system. 
 (cc) “Restricted Stock” means Common Stock awarded to a Participant pursuant
to Section 7 hereof that is subject to certain vesting conditions and other restrictions. 
 (dd) “Restricted Stock
Unit” means an unfunded, unsecured right to receive, on the applicable settlement date, one share of Common Stock or an amount in cash or other consideration determined by the Administrator equal to the value thereof as of such payment
date, which right may be subject to certain vesting conditions and other restrictions. 
 (ee) “Section 409A”
means Section 409A of the Code and all regulations, guidance, compliance programs and other interpretative authority thereunder. 

(ff) “Securities Act” means the Securities Act of 1933, as amended from time to time. 

(gg) “Securities Exchange” shall mean the securities exchange or any other national market system or automated
quotation system on which the Company’s common stock is listed, quoted, or traded. 
 (hh) “Service” means a
Service Provider’s employment or service with the Company, whether in the capacity of an Employee, a Director or a Consultant. A Service Provider’s Service shall not be deemed to have terminated merely because of a change in the capacity
in which the Service Provider renders Service to the Company or a change in the Company for which the Service Provider renders such Service, provided that there is no interruption or termination of the Service Provider’s Service. Furthermore, a
Service Provider’s Service with the Company shall not be deemed to have terminated if the Service Provider takes any military leave, sick leave, or other bona fide leave of absence approved by the Company; provided, however, that if any such
leave exceeds ninety (90) days, on the ninety-first (91st) day of such leave the Service Provider’s Service shall be deemed to have terminated unless the Service Provider’s right to return to Service with the Company is
guaranteed by statute or contract. Notwithstanding the foregoing, unless otherwise designated by the Company or required by law, a leave of absence shall not be treated as Service for purposes of determining vesting under the Service Provider’s
Award Agreement. The Service Provider’s Service shall be deemed to have terminated upon an actual termination of Service. Subject to the foregoing, the Company, in its discretion, shall determine whether the Service Provider’s Service has
terminated and the effective date of such termination. 
 (ii) “Service Provider” means an Employee,
Consultant or Director. 
 (jj) “Termination of Service” means the date the Participant ceases to be a
Service Provider. 
 3. Eligibility. Service Providers are eligible to be granted Awards under the Plan, subject to the
limitations described herein. Incentive Stock Options may be granted only to Employees of the Company and Nonstatutory Options, Restricted Stock, Restricted Stock Units or Other Stock-Based Awards may be granted to any Service Provider of the
Company, in each case, as designated by the Administrator. 

  
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 4. Administration and Delegation.  

(a) Administration. The Plan will be administered by the Administrator. The Administrator shall have authority to determine which
Service Providers will receive Awards, to grant Awards and to set all terms and conditions of Awards (including, but not limited to, vesting, exercise and forfeiture provisions). In addition, the Administrator shall have the authority to take all
actions and make all determinations contemplated by the Plan and to adopt, amend and repeal such administrative rules, guidelines and practices relating to the Plan as it shall deem advisable. The Administrator may correct any defect or ambiguity,
supply any omission or reconcile any inconsistency in the Plan or any Award in the manner and to the extent it shall deem necessary or appropriate to carry the Plan and any Awards into effect, as determined by the Administrator. 

(b) Appointment of Committees. To the extent permitted by Applicable Laws, the Board may delegate any or all of its powers under
the Plan to one or more Committees. The Board may abolish any Committee at any time and re-vest in itself any previously delegated authority. 

(c) Delegation of Authority. To the extent permitted by Applicable Laws or the rules of any Securities Exchange, the Board or Committee
may from time to time delegate to a committee of one or more members of the Board or one or more officers of the Company the authority to grant or amend Awards or to take other administrative actions pursuant to this Section 4; provided,
however, that in no event shall an officer of the Company be delegated the authority to grant awards to, or amend awards held by, the following individuals, in each case to the extent applicable: (a) individuals who are subject to
Section 16 of the Exchange Act, (b) “covered employees” as defined for purposes of Section 162(m) of the Code, or (c) officers of the Company (or Directors) to whom authority to grant or amend Awards has been delegated
hereunder; provided further, that any delegation of administrative authority shall only be permitted to the extent it is permissible under Section 162(m) of the Code and applicable securities laws or the rules of any Securities Exchange.
Any delegation hereunder shall be subject to the restrictions and limits that the Board or Committee specifies at the time of such delegation, and the Board may at any time rescind the authority so delegated or appoint a new delegate At all times,
the delegatee appointed under this Section 4(c) shall serve in such capacity at the pleasure of the Board and the Committee. 
 5.
Stock Available for Awards. 
 (a) Number of Shares. Subject to adjustment under Section 9
hereof, Awards may be made under the Plan covering up to 2,750,000 shares of Common Stock, plus a total of 1,864,563 shares of Common Stock remaining available for issuance under the Prior Plan, for an aggregate total of 4,614,563 shares of Common
Stock. Subject to adjustment under Section 9 hereof, 4,614,563 shares of Common Stock be available for issuance pursuant to the exercise of Incentive Stock Options. If any Award under this Plan or an outstanding unexercised stock option under
the Prior Plan (such stock option, a “Prior Plan Award”) expires or lapses or is terminated, surrendered or canceled without having been fully exercised or is forfeited in whole or in part (including as the
result of shares of Common Stock subject to such Award being repurchased by the Company at or below the original issuance price), in any case in a manner that results in any shares of Common Stock covered by such Award or Prior Plan Award not being
issued or being so reacquired by the Company, the unused Common Stock covered by such Award or Prior Plan Award shall again be available for the grant of Awards under this Plan. Further, shares of Common Stock delivered (either by actual delivery or
attestation) to the Company by a Participant to satisfy the applicable exercise or purchase price of an Award 

  
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or Prior Plan Award and/or to satisfy any applicable tax withholding obligation (including shares retained by the Company from the Award or Prior Plan Award being exercised or
purchased and/or creating the tax obligation) shall be added to the number of shares of Common Stock available for the grant of Awards under the Plan. However, in the case of Incentive Stock Options (as hereinafter defined), the foregoing provisions
shall be subject to any limitations under the Code. Shares of Common Stock issued under the Plan may consist in whole or in part of authorized but unissued shares, shares purchased on the open market or treasury shares. The Administrator shall make
all determinations under the Plan in the Administrator’s sole discretion and all such determinations shall be final and binding on all persons having or claiming any interest in the Plan or in any Award. After the date that the stockholders of
the Company approve this Plan, no awards may be granted under the Prior Plan, provided, however, that any Prior Plan Awards that are outstanding as of such date shall continue to be subject to the terms and conditions of the Prior Plan.

 (b) Substitute Awards. In connection with a merger or consolidation of an entity with the Company or the acquisition by the
Company of property or stock of an entity, the Administrator may grant Awards in substitution for any options or other stock or stock-based awards granted prior to such merger or consolidation by such entity or an affiliate thereof. Substitute
Awards may be granted on such terms as the Administrator deems appropriate in the circumstances, notwithstanding any limitations on Awards contained in the Plan. Substitute Awards shall not count against the overall share limit set forth in
Section 5(a) hereof, except as may be required by reason of Section 422 of the Code. 
 6. Stock Options.
 
 (a) General. The Administrator may grant Options to any Service Provider, subject to the limitations on
Incentive Stock Options described below. The Administrator shall determine the number of shares of Common Stock to be covered by each Option, the exercise price of each Option and the conditions and limitations applicable to the exercise of each
Option, including conditions relating to Applicable Laws, as it considers necessary or advisable. 
 (b) Incentive Stock
Options. The Administrator may grant Options intended to qualify as Incentive Stock Options only to Employees of the Company, any of the Company’s present or future “parent corporations” or “subsidiary corporations”
as defined in Sections 424(e) or (f) of the Code, respectively, and any other entities the employees of which are eligible to receive Incentive Stock Options under the Code. All Options intended to qualify as Incentive Stock Options shall be
subject to and shall be construed consistently with the requirements of Section 422 of the Code. Neither the Company nor the Administrator shall have any liability to a Participant, or any other party, (i) if an Option (or any part
thereof) which is intended to qualify as an Incentive Stock Option fails to qualify as an Incentive Stock Option or (ii) for any action or omission by the Administrator that causes an Option not to qualify as an Incentive Stock Option,
including without limitation, the conversion of an Incentive Stock Option to a Nonstatutory Stock Option or the grant of an Option intended as an Incentive Stock Option that fails to satisfy the requirements under the Code applicable to an Incentive
Stock Option. Any Option that is intended to qualify as an Incentive Stock Option, but fails to so qualify for any reason, including without limitation, the portion of any Option becoming exercisable in excess of the $100,000 limitation described in
Treasury Regulation Section 1.422-4, shall be treated as a Nonstatutory Stock Option for all purposes. 
 (c) Exercise
Price. The Administrator shall establish the exercise price of each Option and specify the exercise price in the applicable Award Agreement. The exercise price shall be not less than 100% of the Fair Market Value on the date the Option is
granted. In the case of an Incentive 

  
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Stock Option granted to an employee who, at the time of grant of the Option, owns (or is treated as owning under Section 424 of the Code) stock representing more than 10% of the voting power
of all classes of stock of the Company (or a “parent corporation” or “subsidiary corporation” thereof within the meaning of Sections 424(e) or 424(f) of the Code, respectively), the per share exercise price shall be no less than
110% of the Fair Market Value on the date the Option is granted. 
 (d) Duration of Options. Each Option shall be exercisable at
such times and subject to such terms and conditions as the Administrator may specify in the applicable Award Agreement, provided that the term of any Option shall not exceed ten years. In the case of an Incentive Stock Option granted to an employee
who, at the time of grant of the Option, owns (or is treated as owning under Section 424 of the Code) stock representing more than 10% of the voting power of all classes of stock of the Company (or a “parent corporation” or
“subsidiary corporation” thereof within the meaning of Sections 424(e) or 424(f) of the Code, respectively), the term of the Option shall not exceed five years. 

(e) Exercise of Option; Notification of Disposition. Options may be exercised by delivery to the Company of a written notice of
exercise, in a form approved by the Administrator (which may be an electronic form), signed by the person authorized to exercise the Option, together with payment in full (i) as specified in Section 6(f) hereof for the number of shares for
which the Option is exercised and (ii) as specified in Section 10(e) hereof for any applicable withholding taxes. Unless otherwise determined by the Administrator, an Option may not be exercised for a fraction of a share of Common Stock.
If an Option is designated as an Incentive Stock Option, the Participant shall give prompt notice to the Company of any disposition or other transfer of any shares of Common Stock acquired from the Option if such disposition or transfer is made
(i) within two years from the grant date with respect to such Option or (ii) within one year after the transfer of such shares to the Participant (other than any such disposition made in connection with a Change in Control). Such notice
shall specify the date of such disposition or other transfer and the amount realized, in cash, other property, assumption of indebtedness or other consideration, by the Participant in such disposition or other transfer. 

(f) Payment Upon Exercise. Common Stock purchased upon the exercise of an Option granted under the Plan shall be paid for in cash
or by check, payable to the order of the Company, or, to the extent permitted by the Administrator, by: 
 (i)(A) delivery of
an irrevocable and unconditional undertaking by a broker acceptable to the Company to deliver promptly to the Company sufficient funds to pay the exercise price and any required tax withholding, or (B) delivery by the Participant to the Company
of a copy of irrevocable and unconditional instructions to a broker acceptable to the Company to deliver promptly to the Company cash or a check sufficient to pay the exercise price and any required tax withholding (in either case, a
“Cashless Exercise”); 
 (ii) delivery (either by actual delivery or attestation) of shares of Common
Stock owned by the Participant valued at their Fair Market Value, provided (A) such method of payment is then permitted under Applicable Laws, (B) such Common Stock, if acquired directly from the Company, was owned by the Participant for
such minimum period of time, if any, as may be established by the Company at any time, and (C) such Common Stock is not subject to any repurchase, forfeiture, unfulfilled vesting or other similar requirements; 

(iii) surrendering shares of Common Stock then issuable upon exercise of the Option valued at their Fair Market Value on the
date of exercise; 
 (iv) delivery of a promissory note of the Participant to the Company on terms determined by the
Administrator; 

  
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 (v) delivery of property of any other kind which constitutes good and valuable
consideration as determined by the Administrator; or 
 (vi) any combination of the above permitted forms of payment
(including cash or check). 
 (g) Early Exercise of Options. The Administrator may provide in the terms of an Award Agreement that
the Service Provider may exercise an Option in whole or in part prior to the full vesting of the Option in exchange for unvested shares of Restricted Stock with respect to any unvested portion of the Option so exercised. Shares of Restricted Stock
acquired upon the exercise of any unvested portion of an Option shall be subject to such terms and conditions as the Administrator shall determine. 

7. Restricted Stock; Restricted Stock Units. 

(a) General. The Administrator may grant Restricted Stock, or the right to purchase Restricted Stock, to any Service Provider,
subject to the right of the Company to repurchase all or part of such shares at their issue price or other stated or formula price from the Participant (or to require forfeiture of such shares if issued at no cost) in the event that conditions
specified by the Administrator in the applicable Award Agreement are not satisfied prior to the end of the applicable restriction period or periods established by the Administrator for such Award. In addition, the Administrator may grant to
Service Providers Restricted Stock Units, which may be subject to vesting and forfeiture conditions during applicable restriction period or periods, as set forth in an applicable Award Agreement. 

(b) Terms and Conditions for All Restricted Stock and Restricted Stock Unit Awards. The Administrator shall determine and set
forth in the applicable Award Agreement the terms and conditions applicable to each Restricted Stock and Restricted Stock Unit Award, including the conditions for vesting and repurchase (or forfeiture) and the issue price, in each case, if any.

(c) Additional Provisions Relating to Restricted Stock.  

(i) Dividends. Participants holding shares of Restricted Stock will be entitled to all ordinary cash dividends paid
with respect to such shares, unless otherwise provided by the Administrator in the applicable Award Agreement. In addition, unless otherwise provided by the Administrator, if any dividends or distributions are paid in shares, or consist of a
dividend or distribution to holders of Common Stock of property other than an ordinary cash dividend, the shares or other property will be subject to the same restrictions on transferability and forfeitability as the shares of Restricted Stock with
respect to which they were paid. Each dividend payment will be made as provided in the applicable Award Agreement, but in no event later than the end of the calendar year in which the dividends are paid to stockholders of that class of stock or, if
later, the 15th day of the third month following the later of (A) the date the dividends are paid to stockholders of that class of stock, and (B) the date the dividends are no longer subject to forfeiture.

(ii) Stock Certificates. The Company may require that any stock certificates issued in respect of shares of
Restricted Stock be deposited in escrow by the Participant, together with a stock power endorsed in blank, with the Company (or its designee).

  
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 (d) Additional Provisions Relating to Restricted Stock Units. 

(i) Settlement. Upon the vesting of a Restricted Stock Unit, the Participant shall be entitled to receive from the Company one
share of Common Stock or an amount of cash or other property equal to the Fair Market Value of one share of Common Stock on the settlement date, as provided in the applicable Award Agreement. The Administrator may provide that settlement of
Restricted Stock Units shall occur upon or as soon as reasonably practicable after the vesting of the Restricted Stock Units or shall instead be deferred, on a mandatory basis or at the election of the Participant, in a manner that complies with
Section 409A.
 (ii) Voting Rights. A Participant shall have no voting rights with respect to any Restricted Stock Units
unless and until shares are delivered in settlement thereof.
 (iii) Dividend Equivalents. To the extent provided by the
Administrator, a grant of Restricted Stock Units may provide a Participant with the right to receive Dividend Equivalents. Dividend Equivalents may be paid currently or credited to an account for the Participant, may be settled in cash and/or
shares of Common Stock and may be subject to the same restrictions on transfer and forfeitability as the Restricted Stock Units with respect to which the Dividend Equivalents are paid, as determined by the Administrator, subject, in each case, to
such terms and conditions as the Administrator shall establish and set forth in the applicable Award Agreement. 
 8. Other
Stock-Based Awards.  
 Other Stock-Based Awards may be granted hereunder to Participants, including, without
limitation, Awards entitling Participants to receive shares of Common Stock to be delivered in the future. Such Other Stock-Based Awards shall also be available as a form of payment in the settlement of other Awards granted under the Plan, as
stand-alone payments and/or as payment in lieu of compensation to which a Participant is otherwise entitled. Other Stock-Based Awards may be paid in shares of Common Stock, cash or other property, as the Administrator shall
determine. Subject to the provisions of the Plan, the Administrator shall determine the terms and conditions of each Other Stock-Based Award, including any purchase price, transfer restrictions, vesting conditions and other terms and conditions
applicable thereto, which shall be set forth in the applicable Award Agreement. 
 9. Adjustments for Changes in Common Stock and
Certain Other Events. 
 (a) In the event that the Administrator determines that any dividend or other
distribution (whether in the form of cash, Common Stock, other securities, or other property), reorganization, merger, consolidation, combination, repurchase, recapitalization, liquidation, dissolution, or sale, transfer, exchange or other
disposition of all or substantially all of the assets of the Company, or sale, transfer, exchange or other disposition of Common Stock or other securities of the Company, issuance of warrants or other rights to purchase Common Stock or other
securities of the Company, or other similar corporate transaction or event, as determined by the Administrator, affects the Common Stock such that an adjustment is determined by the Administrator to be appropriate in order to prevent dilution or
enlargement of the benefits or potential benefits intended by the Company to be made available under the Plan or with respect to any Award, then the Administrator may, in such manner as it may deem equitable, adjust any or all of: 

(i) the number and kind of shares of Common Stock (or other securities or property) with respect to which Awards may be granted
or awarded (including, but not limited to, adjustments of the limitations in Section 5 hereof on the maximum number and kind of shares which may be issued); 

(ii) the number and kind of shares of Common Stock (or other securities or property) subject to outstanding Awards; 

  
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 (iii) the grant or exercise price with respect to any Award; and 

(iv) the terms and conditions of any Awards (including, without limitation, any applicable financial or other performance
“targets” specified in an Award Agreement). 
 (b) In the event of any transaction or event described in Section 9(a) hereof
(including without limitation any Change in Control) or any unusual or nonrecurring transaction or event affecting the Company or the financial statements of the Company, or any change in any Applicable Laws or accounting principles, the
Administrator, on such terms and conditions as it deems appropriate, either by the terms of the Award or by action taken prior to the occurrence of such transaction or event and either automatically or upon the Participant’s request, is hereby
authorized to take any one or more of the following actions whenever the Administrator determines that such action is appropriate in order to (x) prevent dilution or enlargement of the benefits or potential benefits intended by the Company to
be made available under the Plan or with respect to any Award granted or issued under the Plan, (y) to facilitate such transaction or event or (z) give effect to such changes in Applicable Laws or accounting principles:  

(i) To provide for the cancellation of any such Award in exchange for either an amount of cash or other property with a value
equal to the amount that could have been obtained upon the exercise or settlement of such Award or realization of the Participant’s rights had such Award been currently exercisable, payable and fully vested, as applicable; provided that, if the
amount that could have been obtained upon the exercise or settlement of such Award or realization of the Participant’s rights, in any case, is equal to or less than zero, then such Award may be terminated without payment; 

(ii) To provide that such Award shall vest and, to the extent applicable, be exercisable as to all shares covered thereby,
notwithstanding anything to the contrary in the Plan or the provisions of such Award; 
 (iii) To provide that such Award be
assumed by the successor or survivor corporation, or a parent or subsidiary thereof, or shall be substituted for by awards covering the stock of the successor or survivor corporation, or a parent or subsidiary thereof, with appropriate adjustments
as to the number and kind of shares and applicable exercise or purchase price, in all cases, as determined by the Administrator; 

(iv) To make adjustments in the number and type of shares of Common Stock (or other securities or property) subject to
outstanding Awards, and/or in the terms and conditions of (including the grant or exercise price), and the criteria included in, outstanding Awards which may be granted in the future; 

(v) To replace such Award with other rights or property selected by the Administrator; and/or 

(vi) To provide that the Award will terminate and cannot vest, be exercised or become payable after the applicable event. 

(c) In connection with the occurrence of any Equity Restructuring, and notwithstanding anything to the contrary in this Section 9, the
Administrator will equitably adjust each outstanding Award, which adjustments may include adjustments to the number and type of securities subject to each outstanding Award and/or the exercise price or grant price thereof, if applicable, the grant
of new Awards to Participants, and/or the making of a cash payment to Participants, as the Administrator 

  
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deems appropriate to reflect such Equity Restructuring. The adjustments provided under this Section 9(c) shall be nondiscretionary and shall be final and binding on the affected Participant
and the Company; provided that whether an adjustment is equitable shall be determined by the Administrator. 
 (d) In the event of any
pending stock dividend, stock split, combination or exchange of shares, merger, consolidation or other distribution (other than normal cash dividends) of Company assets to stockholders, or any other change affecting the shares of Stock or the share
price of the Stock, including any Equity Restructuring, for reasons of administrative convenience the Administrator may refuse to permit the exercise of any Award during a period of up to thirty days prior to the consummation of any such
transaction. 
 (e) Except as expressly provided in the Plan or Award Agreement or pursuant to action of the Administrator under the Plan,
no Participant shall have any rights by reason of any subdivision or consolidation of shares of stock of any class, the payment of any dividend, any increase or decrease in the number of shares of stock of any class or any dissolution, liquidation,
merger, or consolidation of the Company or any other corporation. Except as expressly provided in the Plan or pursuant to action of the Administrator under the Plan, no issuance by the Company of shares of stock of any class, or securities
convertible into shares of stock of any class, shall affect, and no adjustment by reason thereof shall be made with respect to, the number of shares of Stock subject to an Award or the grant or exercise price of any Award. The existence of the Plan,
any Award Agreements and the Awards granted hereunder shall not affect or restrict in any way the right or power of the Company to make or authorize (i) any adjustment, recapitalization, reorganization or other change in the Company’s
capital structure or its business, (ii) any merger, consolidation dissolution or liquidation of the Company or sale of Company assets or (iii) any sale or issuance of securities, including without limitation, securities with rights
superior to those of the Common Stock or which are convertible into or exchangeable for Common Stock. The Administrator may treat Participants and Awards (or portions thereof) differently under this Section 9. 

10. General Provisions Applicable to Awards.  

(a) Transferability of Awards. Except as the Administrator may otherwise determine or provide in an Award Agreement or otherwise,
in any case in accordance with Applicable Laws, Awards shall not be sold, assigned, transferred, pledged or otherwise encumbered by the person to whom they are granted, either voluntarily or by operation of law, except by will or the laws of descent
and distribution, and, during the life of the Participant, shall be exercisable only by the Participant. References to a Participant, to the extent relevant in the context, shall include references to authorized transferees. 

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

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

(d) Termination of Status. The Administrator shall determine the effect on an Award of the disability, death, retirement,
authorized leave of absence or any other change or purported change in a Participant’s Service Provider status and the extent to which, and the period during which, the Participant, the Participant’s legal representative, conservator,
guardian or Designated Beneficiary may exercise rights under the Award, if applicable. 

  
 11 

 (e) Withholding. Each Participant shall pay to the Company, or make provision
satisfactory to the Administrator for payment of, any taxes required by law to be withheld in connection with Awards to such Participant no later than the date of the event creating the tax liability. Except as the Administrator may otherwise
determine, all such payments shall be made in cash or by certified check. Notwithstanding the foregoing, to the extent permitted by the Administrator, Participants may satisfy such tax obligations in whole or in part by delivery of shares of Common
Stock, including shares retained from the Award creating the tax obligation, valued at their Fair Market Value. The Company may, to the extent permitted by Applicable Laws, deduct any such tax obligations from any payment of any kind otherwise due
to a Participant. The Administrator may also permit payment of such tax obligations by Cashless Exercise, by such other consideration as permitted by the Administrator from time to time, or any combination of consideration permitted under this
Section 10(e). 
 (f) Amendment of Award. The Administrator may amend, modify or terminate any outstanding Award, including
but not limited to, substituting therefor another Award of the same or a different type, changing the date of exercise or settlement, and converting an Incentive Stock Option to a Nonstatutory Stock Option. The Participant’s consent to such
action shall be required unless (i) the Administrator determines that the action, taking into account any related action, would not materially and adversely affect the Participant, or (ii) the change is permitted under Section 9 and
11(f) hereof. 
 (g) Conditions on Delivery of Stock. The Company will not be obligated to deliver any shares of Common Stock
pursuant to the Plan or to remove restrictions from shares previously delivered under the Plan until (i) all conditions of the Award have been met or removed to the satisfaction of the Company, (ii) in the opinion of the Company’s
counsel, all other legal matters in connection with the issuance and delivery of such shares have been satisfied, including any applicable securities laws and any applicable stock exchange or stock market rules and regulations, and (iii) the
Participant has executed and delivered to the Company such representations or agreements as the Administrator deems necessary or appropriate to satisfy the requirements of any Applicable Laws. The inability of the Company to obtain authority from
any regulatory body having jurisdiction, which authority is determined by the Administrator to be necessary to the lawful issuance and sale of any securities hereunder, shall relieve the Company of any liability in respect of the failure to issue or
sell such shares as to which such requisite authority shall not have been obtained. 
 (h) Acceleration. The Administrator may
at any time provide that any Award shall become immediately vested and/or exercisable in full or in part, free of some or all restrictions or conditions, or otherwise realizable in full or in part, as the case may be. 

11. Miscellaneous.  

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

  
 12 

 (b) No Rights As Stockholder; Certificates. Subject to the provisions of the
applicable Award Agreement, no Participant or Designated Beneficiary shall have any rights as a stockholder with respect to any shares of Common Stock to be distributed with respect to an Award until becoming the record holder of such shares.
Notwithstanding any other provision of the Plan, unless otherwise determined by the Administrator or required by any Applicable Laws, the Company shall not be required to deliver to any Participant certificates evidencing shares of Common Stock
issued in connection with any Award and instead such shares of Common Stock may be recorded in the books of the Company (or, as applicable, its transfer agent or stock plan administrator). The Company may place legends on stock certificates issued
under the Plan deemed necessary or appropriate by the Administrator in order to comply with Applicable Laws. 
 (c) Effective Date and
Term of Plan. The Plan shall become effective on the date on which it is adopted by the Board. No Awards shall be granted under the Plan after the completion of ten years from the earlier of (i) the date on which the Plan was adopted
by the Board or (ii) the date the Plan was approved by the Company’s stockholders, but Awards previously granted may extend beyond that date in accordance with the terms of the Plan. 

(d) Amendment of Plan. The Administrator may amend, suspend or terminate the Plan or any portion thereof at any time; provided
that no amendment of the Plan shall materially and adversely affect any Award outstanding at the time of such amendment without the consent of the affected Participant. Awards outstanding under the Plan at the time of any suspension or termination
of the Plan shall continue to be governed in accordance with the terms of the Plan and the applicable Award Agreement, as in effect prior to such suspension or termination. The Board shall obtain stockholder approval of any Plan amendment to the
extent necessary to comply with Applicable Laws. 
 (e) Provisions for Foreign Participants. The Administrator may modify Awards
granted to Participants who are foreign nationals or employed outside the United States or establish subplans or procedures under the Plan to address differences in laws, rules, regulations or customs of such foreign jurisdictions with respect to
tax, securities, currency, employee benefit or other matters. 
 (f) Section 409A.  

(i) General. The Company intends that all Awards be structured in compliance with, or to satisfy an exemption from,
Section 409A, such that no adverse tax consequences, interest, or penalties under Section 409A apply in connection with any Awards. Notwithstanding anything herein or in any Award Agreement to the contrary, the Administrator may, without a
Participant’s prior consent, amend this Plan and/or Awards, adopt policies and procedures, or take any other actions (including amendments, policies, procedures and actions with retroactive effect) as are necessary or appropriate to preserve
the intended tax treatment of Awards under the Plan, including without limitation, any such actions intended to (A) exempt this Plan and/or any Award from the application of Section 409A, and/or (B) comply with the requirements of
Section 409A, including without limitation any such regulations, guidance, compliance programs and other interpretative authority that may be issued after the date of grant of any Award. The Company makes no representations or warranties as to
the tax treatment of any Award under Section 409A or otherwise. The Company shall have no obligation under this Section 11(f) or otherwise to take any action (whether or not described herein) to avoid the imposition of taxes, penalties or
interest under Section 409A with respect to any Award and shall have no liability to any Participant or any other person if any Award, compensation or other benefits under the Plan are determined to constitute non-compliant, “nonqualified
deferred compensation” subject to the imposition of taxes, penalties and/or interest under Section 409A. 
 (ii)
Separation from Service. With respect to any Award that constitutes “nonqualified deferred compensation” under Section 409A, any payment or settlement of such Award that is to be made upon a termination of a Participant’s
Service Provider relationship shall, 

  
 13 

 
to the extent necessary to avoid the imposition of taxes under Section 409A, be made only upon the Participant’s “separation from service” (within the meaning of
Section 409A), whether such “separation from service” occurs upon or subsequent to the termination of the Participant’s Service Provider relationship. For purposes of any such provision of this Plan or any Award Agreement
relating to any such payments or benefits, references to a “termination,” “termination of employment” or like terms shall mean “separation from service.” 

(iii) Payments to Specified Employees. Notwithstanding any contrary provision in the Plan or any Award Agreement, any
payment(s) of “nonqualified deferred compensation” that are otherwise required to be made under an Award to a “specified employee” (as defined under Section 409A and determined by the Administrator) as a result of his or her
“separation from service” shall, to the extent necessary to avoid the imposition of taxes under Code Section 409A(a)(2)(B)(i), be delayed until the expiration of the six-month period immediately following such “separation from
service” (or, if earlier, until the date of death of the specified employee) and shall instead be paid (in a manner set forth in the Award agreement) on the day that immediately follows the end of such six-month period or as soon as
administratively practicable thereafter (without interest). Any payments of “nonqualified deferred compensation” under such Award that are, by their terms, payable more than six months following the Participant’s “separation from
service” shall be paid at the time or times such payments are otherwise scheduled to be made. 
 (g) Limitations on
Liability. Notwithstanding any other provisions of the Plan, no individual acting as a director, officer, other employee or agent of the Company will be liable to any Participant, former Participant, spouse, beneficiary, or any other person
for any claim, loss, liability, or expense incurred in connection with the Plan or any Award, nor will such individual be personally liable with respect to the Plan because of any contract or other instrument he or she executes in his or her
capacity as an Administrator, director, officer, other employee or agent of the Company. The Company will indemnify and hold harmless each director, officer, other employee and agent of the Company to whom any duty or power relating to the
administration or interpretation of the Plan has been or will be granted or delegated, against any cost or expense (including attorneys’ fees) or liability (including any sum paid in settlement of a claim with the Administrator’s approval)
arising out of any act or omission to act concerning this Plan unless arising out of such person’s own fraud or bad faith.
 (h)
Lock-Up Period. The Company may, at the request of any representative of the underwriters (the “Managing Underwriter”) or otherwise, in connection with any registration of the offering of any securities of the Company
under the Securities Act, prohibit Participants from, directly or indirectly, selling or otherwise transferring any shares of Common Stock or other securities of the Company during a period of up to one hundred eighty days following the effective
date of a registration statement of the Company filed under the Securities Act. 
 (i) Data Privacy. As a condition of receipt of any
Award, each Participant explicitly and unambiguously consents to the collection, use and transfer, in electronic or other form, of personal data as described in this paragraph by and among, as applicable, the Company and its subsidiaries and
affiliates for the exclusive purpose of implementing, administering and managing the Participant’s participation in the Plan. The Company and its subsidiaries and affiliates may hold certain personal information about a Participant, including
but not limited to, the Participant’s name, home address and telephone number, date of birth, social security or insurance number or other identification number, salary, nationality, job title(s), any shares of stock held in the Company or any
of its subsidiaries and affiliates, details of all Awards, in each case, for the purpose of implementing, managing and administering the Plan and Awards (the “Data”). The Company and its subsidiaries and affiliates may

  
 14 

 
transfer the Data amongst themselves as necessary for the purpose of implementation, administration and management of a Participant’s participation in the Plan, and the Company and its
subsidiaries and affiliates may each further transfer the Data to any third parties assisting the Company in the implementation, administration and management of the Plan. These recipients may be located in the Participant’s country, or
elsewhere, and the Participant’s country may have different data privacy laws and protections than the recipients’ country. Through acceptance of an Award, each Participant authorizes such recipients to receive, possess, use, retain and
transfer the Data, in electronic or other form, for the purposes of implementing, administering and managing the Participant’s participation in the Plan, including any requisite transfer of such Data as may be required to a broker or other
third party with whom the Company or the Participant may elect to deposit any shares of Common Stock. The Data related to a Participant will be held only as long as is necessary to implement, administer, and manage the Participant’s
participation in the Plan. A Participant may, at any time, view the Data held by the Company with respect to such Participant, request additional information about the storage and processing of the Data with respect to such Participant, recommend
any necessary corrections to the Data with respect to the Participant or refuse or withdraw the consents herein in writing, in any case without cost, by contacting his or her local human resources representative. The Company may cancel
Participant’s ability to participate in the Plan and, in the Administrator’s discretion, the Participant may forfeit any outstanding Awards if the Participant refuses or withdraws his or her consents as described herein. For more
information on the consequences of refusal to consent or withdrawal of consent, Participants may contact their local human resources representative. 

(j) Severability. In the event any portion of the Plan or any action taken pursuant thereto shall be held illegal or invalid for any
reason, the illegality or invalidity shall not affect the remaining parts of the Plan, and the Plan shall be construed and enforced as if the illegal or invalid provisions had not been included, and the illegal or invalid action shall be null and
void. 
 (k) Governing Documents. In the event of any contradiction between the Plan and any Award Agreement or any other written
agreement between a Participant and the Company or any Subsidiary of the Company that has been approved by the Administrator, the terms of the Plan shall govern, unless it is expressly specified in such Award Agreement or other written document that
a specific provision of the Plan shall not apply. 
 (m) Governing Law. The provisions of the Plan and all Awards made hereunder
shall be governed by and interpreted in accordance with the laws of the State of Delaware, disregarding choice-of-law principles of the law of any state that would require the application of the laws of a jurisdiction other than such state. 

(n) Restrictions on Shares; Claw-back Provisions. Shares of Common Stock acquired in respect of Awards shall be subject to such terms
and conditions as the Administrator shall determine, including, without limitation, restrictions on the transferability of shares of Common Stock, the right of the Company to repurchase shares of Common Stock, the right of the Company to require
that shares of Common Stock be transferred in the event of certain transactions, tag-along rights, bring-along rights, redemption and co-sale rights and voting requirements. Such terms and conditions may be additional to those contained in the Plan
and may, as determined by the Administrator, be contained in the applicable Award Agreement or in an exercise notice, stockholders’ agreement or in such other agreement as the Administrator shall determine, in each case in a form determined by
the Administrator. The issuance of such shares of Common Stock shall be conditioned on the Participant’s consent to such terms and conditions and the Participant’s entering into such agreement or agreements. All Awards (including any
proceeds, gains or other economic benefit actually or constructively received by Participant upon any receipt or exercise of any Award or upon the receipt or resale of any shares of Common Stock underlying the Award) shall be subject to the
provisions of any claw-back policy implemented by the Company, 

  
 15 

 
including, without limitation, any claw-back policy adopted to comply with the requirements of the Dodd-Frank Wall Street Reform and Consumer Protection Act and any rules or regulations
promulgated thereunder, to the extent set forth in such claw-back policy and/or in the applicable Award Agreement. 
 (o) Titles and
Headings. The titles and headings of the Sections in the Plan are for convenience of reference only and, in the event of any conflict, the text of the Plan, rather than such titles or headings, shall control. 

(p) Conformity to Securities Laws. Participant acknowledges that the Plan is intended to conform to the extent necessary with all
provisions of the Securities Act and the Exchange Act and any and all regulations and rules promulgated by the Securities and Exchange Commission thereunder, and state securities laws and regulations. Notwithstanding anything herein to the contrary,
the Plan and all Awards granted hereunder shall be administered only in such a manner as to conform to such laws, rules and regulations. To the extent permitted by Applicable Laws, the Plan and all Award Agreements shall be deemed amended to the
extent necessary to conform to such laws, rules and regulations. 

*    *    *    *    * 

IN WITNESS WHEREOF, the undersigned Secretary of the Company certifies that the foregoing sets forth the Ambrx, Inc. 2013 Equity Incentive
Plan as duly adopted by the Board of Directors of the Company on February 5, 2013, and as approved and adopted by the stockholders of the Company on March 14, 2013. 

 

	
	
	/s/ John W. Wallen, III
	Secretary

  
 16 

 AMBRX, INC. 

2013 EQUITY INCENTIVE PLAN 

CALIFORNIA SUPPLEMENT 
 The
Administrator has adopted this supplement for purposes of satisfying the requirements of Section 25102(o) of the California Corporations Code and the regulations issued thereunder (“Section 25102(o)”). Notwithstanding
anything to the contrary contained in the Plan and except as otherwise determined by the Administrator, the provisions set forth in this supplement shall apply to all Awards granted under the Plan to a Participant who is a resident of the State of
California on the date of grant (a “California Participant”) and which are intended to be exempt from registration in California pursuant to Section 25102(o). This supplement shall not apply to Awards granted to
California Participants or after the date on which the Company becomes a Publicly Listed Company. Definitions in the Plan are applicable to this supplement. 

1. Additional Limitations On Options.  

(a) Maximum Duration of Options. No Options granted to California Participants will be granted for a term in excess of
10 years. 
 (b) Minimum Exercise Period Following Termination. Unless a California Participant’s Service Provider
relationship is terminated for cause, in the event of termination of such Participant’s Service Provider relationship, to the extent required by Applicable Laws, he or she shall have the right to exercise an Option, to the extent that he or she
was otherwise entitled to exercise such Option on the date employment terminated, as follows: (i) at least six months from the date of termination, if termination was caused by such Participant’s death or Disability and (ii) at least
30 days from the date of termination, if termination was caused other than by such Participant’s death or Disability. 
 2.
Additional Limitations For Restricted Stock Awards, Restricted Stock Units and Other Stock-Based Awards. The terms of all Restricted Stock Awards, Restricted Stock Units and Other Stock-Based Awards granted to California
Participants shall comply, to the extent applicable, with Section 260.140.41 or Section 260.140.42 of the California Code of Regulations. 

3. Adjustments. The Administrator will make such adjustments to an Award held by a California Participant as may be required by
Section 260.140.41 or Section 260.140.42 of the California Code of Regulations. 
 4. Additional Requirement To Provide
Information To California Participants. To the extent required by Section 260.140.46 of the California Code of Regulations, the Company shall provide to each California Participant and to each California Participant who
acquires Common Stock pursuant to the Plan, not less frequently than annually, copies of annual financial statements (which need not be audited). The Company shall not be required to provide such statements to key persons whose duties in connection
with the Company assure their access to equivalent information. In addition, this information requirement shall not apply to the Plan to the extent that it complies with all conditions of Rule 701 of the Securities Act (“Rule
701”) as determined by the Administrator; provided that for purposes of determining such compliance, any registered domestic partner shall be considered a “family member” as that term is defined in Rule 701. 

  
 CS-1 

 5. Stockholder Approval; Additional Limitations On Timing Of
Awards. The Plan will be submitted for the approval of the Company’s stockholders within twelve (12) months after the date of the Board’s adoption of the Plan. Awards may be granted or awarded prior to such
stockholder approval; provided that no Award granted to a California Participant shall become exercisable, vested or realizable, as applicable to such Award, unless the Plan has been approved by the Company’s stockholders within
twelve months before or after the date the Plan was adopted by the Administrator; and provided, further, that if such approval has not been obtained at the end of said twelve-month period, all Awards previously granted or awarded under the Plan
to California Participants shall thereupon be canceled and become null and void. 

  
 CS-2 

 Non-Executive Version 

AMBRX, INC. 
 NOTICE
OF GRANT OF STOCK OPTION 
 (Standard Vesting) 

[Name] (the “Optionee”) has been granted an option (the “Option”) to purchase
certain shares of Stock of Ambrx, Inc. pursuant to the Ambrx, Inc. 2013 Equity Incentive Plan, as amended from time to time (the “Plan”), as follows: 
  

			
	Option Grant Number:	  	
	  
 Date of Option Grant:
	  	
	  
 Number of Option Shares:
	  	
	  
 Exercise Price:
	  	$[ l ] per share
	  
 Vesting Commencement Date:
	  	
	  
 Option Expiration Date:
	  	The date ten (10) years after the Date of Option Grant
	  
 Tax Status of Option:
	  	 ̈          Incentive Stock Option
		  	 ̈          Nonqualified Stock Option

 Vested Shares: Except as provided in the Stock Option Agreement, the number of
“Vested Shares” (disregarding any resulting fractional share) as of any date is determined by multiplying the Number of Option Shares by the “Vested Ratio” determined as of such date as follows: 

[Twenty Five percent (25%) of the total number of Option Shares subject to this Option shall vest on
the first anniversary of the Vesting Commencement Date (rounded up to the next whole number of shares) and 1/48th of the total number of Option Shares subject to this Option (rounded up to the
next whole number of shares) shall vest on each full month of the Optionee’s continuous Service thereafter (measured as of the day of the month corresponding to the Vesting Commencement Date), so that all of the Option Shares shall be vested on
the fourth (4th) anniversary of the Vesting Commencement Date (and, for purposes of clarification, any additional Option Shares remaining unvested on such date due to the foregoing rounding
shall vest on the fourth (4th) anniversary of the Vesting Commencement Date).] 

By their signatures below, the Company and the Optionee agree that the Option is governed by this Notice and by the
provisions of the Plan and the Stock Option Agreement, both of which are attached to and made a part of this document. The Optionee acknowledges receipt of copies of the Plan and the Stock Option Agreement, represents that the Optionee has read and
is familiar with their provisions, and hereby accepts the Option subject to all of their terms and conditions. 
  

							
	AMBRX, INC.	 		 	OPTIONEE
				
	By:	 	  
	 		 	  

		 		 		 	Signature
	Its:	 	 VP, Intellectual Property & Corporate Legal
	 		 	  

		 		 		 	Date
	   10975 North Torrey Pines Road
	 		 	  

	Address	 		 	Address
	   La Jolla, CA 92037
	 		 	  

 ATTACHMENTS:          2013 Equity Incentive Plan, Stock
Option Agreement and Exercise Notice 

  
 1 

 Non-Executive Version 

 

 THE SECURITIES WHICH ARE THE SUBJECT OF THIS AGREEMENT HAVE NOT BEEN QUALIFIED WITH THE
COMMISSIONER OF CORPORATIONS OF THE STATE OF CALIFORNIA AND THE ISSUANCE OF SUCH SECURITIES OR THE PAYMENT OR RECEIPT OF ANY PART OF THE CONSIDERATION THEREFOR PRIOR TO SUCH QUALIFICATION IS UNLAWFUL, UNLESS THE SALE OF SECURITIES IS EXEMPT FROM
QUALIFICATION BY SECTION 25100, 25102, OR 25105 OF THE CALIFORNIA CORPORATIONS CODE. THE RIGHTS OF ALL PARTIES TO THIS AGREEMENT ARE EXPRESSLY CONDITIONED UPON SUCH QUALIFICATION BEING OBTAINED, UNLESS THE SALE IS SO EXEMPT. 

THE SECURITIES WHICH ARE THE SUBJECT OF THIS AGREEMENT HAVE BEEN ACQUIRED FOR INVESTMENT AND NOT WITH A VIEW TO, OR IN CONNECTION WITH, THE
SALE OR DISTRIBUTION THEREOF. NO SUCH SALE OR DISPOSITION MAY BE EFFECTED WITHOUT AN EFFECTIVE REGISTRATION STATEMENT RELATED THERETO OR AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED UNDER THE SECURITIES
ACT OF 1933. 
  
 AMBRX, INC. 

STOCK OPTION AGREEMENT 

(Standard Vesting) 

Ambrx, Inc. has granted to the individual (the “Optionee”) named in the Notice of Grant of Stock
Option (the “Notice”) to which this Stock Option Agreement (the “Option Agreement”) is attached an option (the “Option”) to purchase certain shares of Stock upon the terms and conditions set
forth in the Notice and this Option Agreement. The Option has been granted pursuant to and shall in all respects be subject to the terms and conditions of the Ambrx, Inc. 2013 Equity Incentive Plan, as amended from time to time (the
“Plan”), the provisions of which are incorporated herein by reference. By signing the Notice, the Optionee: (a) represents that the Optionee has received copies of, and has read and is familiar with the terms and conditions of,
the Notice, the Plan and this Option Agreement; (b) accepts the Option subject to all of the terms and conditions of the Notice, the Plan and this Option Agreement; and (c) agrees to accept as binding, conclusive and final all decisions or
interpretations of the Administrator upon any questions arising under the Notice, the Plan or this Option Agreement. 
 1.
     DEFINITIONS AND CONSTRUCTION. 

1.1 Definitions.  Unless otherwise defined herein, capitalized terms shall have the meanings
assigned to such terms in the Notice or the Plan. 
 1.2 Construction.  Captions and titles
contained herein are for convenience only and shall not affect the meaning or interpretation of any provision of this Option Agreement. Except when otherwise indicated by the context, the singular shall include the plural and the plural shall
include the singular. Use of the term “or” is not intended to be exclusive, unless the context clearly requires otherwise. 

  
 2 

 Non-Executive Version 

 

 2.      TAX
CONSEQUENCES. 
 2.1 Tax Status of Option.     This
Option is intended to have the tax status designated in the Notice. 
 (a) Incentive Stock
Option.    If the Notice so designates, this Option is intended to be an Incentive Stock Option within the meaning of Section 422(b) of the Code to the maximum extent permitted, but the Company does not
represent or warrant that this Option qualifies as such. The Optionee should consult with the Optionee’s own tax advisor regarding the tax effects of this Option and the requirements necessary to obtain favorable income tax treatment under
Section 422 of the Code, including, but not limited to, holding period requirements. (NOTE TO OPTIONEE: If the Option is exercised more than three (3) months after the date on which you cease to be an Employee (other than by reason of your
death or permanent and total disability as defined in Section 22(e)(3) of the Code) or otherwise ceases to qualify as an Incentive Stock Option, the Option will be treated as a Nonstatutory Stock Option and not as an Incentive Stock Option to
the extent required by Section 422 of the Code.) 
 (b) Nonstatutory Stock Option.  If
the Notice so designates, this Option is intended to be a Nonstatutory Stock Option and shall not be treated as an Incentive Stock Option within the meaning of Section 422(b) of the Code. 

2.2 ISO Fair Market Value Limitation.  If the Notice designates this Option as an Incentive Stock
Option, then to the extent that the Option (together with all Incentive Stock Options granted to the Optionee under all stock option plans of the Company, including the Plan) becomes exercisable for the first time during any calendar year for
shares having a Fair Market Value greater than one hundred thousand dollars ($100,000), the portion of such options which exceeds such amount will be treated as Nonstatutory Stock Options. For purposes of this Section 2.2, options designated as
Incentive Stock Options are taken into account in the order in which they were granted, and the Fair Market Value of stock is determined as of the time the option with respect to such stock is granted. If the Code is amended to provide for a
different limitation from that set forth in this Section 2.2, such different limitation shall be deemed incorporated herein effective as of the date required or permitted by such amendment to the Code. If the Option is treated as an Incentive
Stock Option in part and as a Nonstatutory Stock Option in part by reason of the limitation set forth in this Section 2.2, the Optionee may designate which portion of such Option the Optionee is exercising. In the absence of such designation,
the Optionee shall be deemed to have exercised the Incentive Stock Option portion of the Option first. Separate certificates representing each such portion shall be issued upon the exercise of the Option. (NOTE TO OPTIONEE: If the aggregate Exercise
Price of the Option (that is, the Exercise Price multiplied by the Number of Option Shares) plus the aggregate exercise price of any other Incentive Stock Options you hold (whether granted pursuant to the Plan or any other stock option plan of the
Company) is greater than $100,000, you should contact the President of the Company to ascertain whether the entire Option qualifies as an Incentive Stock Option.) 

  
 3 

 Non-Executive Version 

 

 3.    ADMINISTRATION. 

All questions of interpretation concerning this Option Agreement shall be determined by the Administrator. All determinations
by the Administrator shall be final and binding upon all persons having an interest in the Option. Any officer of the Company shall have the authority to act on behalf of the Company with respect to any matter, right, obligation, or election which
is the responsibility of or which is allocated to the Company herein, provided, the officer has apparent authority with respect to such matter, right, obligation, or election. 

4.    EXERCISE OF THE OPTION. 

4.1 Right to Exercise.  Except as otherwise provided herein, the Option shall be exercisable on and after
the Vesting Commencement Date and prior to the termination of the Option (as provided in Section 6) in an amount not to exceed the number of Vested Shares less the number of shares previously acquired upon exercise of the Option, subject to the
Company’s repurchase rights set forth in Sections 11 and 12. In no event shall the Option be exercisable for more shares than the Number of Option Shares. 

4.2 Method of Exercise.  Exercise of the Option shall be by written notice to the
Company which must state the election to exercise the Option, the number of whole shares of Stock for which the Option is being exercised and such other representations and agreements as to the Optionee’s investment intent with respect to such
shares as may be required pursuant to the provisions of this Option Agreement. The written notice must be signed by the Optionee and must be delivered in person, by certified or registered mail, return receipt requested, by confirmed facsimile
transmission, or by such other means as the Company may permit, to the President of the Company, or other authorized representative of the Company, prior to the termination of the Option as set forth in Section 6, accompanied by (i) full
payment of the aggregate Exercise Price for the number of shares of Stock being purchased and (ii) an executed copy, if required herein, of the then current form of escrow agreement referenced below. The Option shall be deemed to be exercised
upon receipt by the Company of such written notice, the aggregate Exercise Price, and, if required by the Company, such executed agreement. 

4.3 Payment of Exercise Price. 

(a) Forms of Consideration Authorized.  Except as otherwise provided below,
payment of the aggregate Exercise Price for the number of shares of Stock for which the Option is being exercised shall be made (i) in cash, by check, or cash equivalent, (ii) by tender to the Company, or attestation to the ownership, of
whole shares of Stock owned by the Optionee having a Fair Market Value not less than the aggregate Exercise Price, (iii) by means of a Cashless Exercise, unless the Company, in its sole discretion, determines to terminate or decline to approve
any such program or procedure, or (iv) by any combination of the foregoing. 
 (b) Tender of
Stock.  Notwithstanding the foregoing, the Option may not be exercised by tender to the Company, or attestation to the ownership, of shares of Stock to the extent such tender or attestation would constitute a
violation of the provisions of any law, regulation or agreement restricting the redemption of the Company’s stock. The Option may not be exercised by tender to the Company, or attestation to the ownership, of shares of Stock unless

  
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such shares either have been owned by the Optionee for more than six (6) months (and not used for another option exercise by attestation during such period) or were not acquired, directly or
indirectly, from the Company. 
 4.4 Tax Withholding.  At the time the Option is
exercised, in whole or in part, or at any time thereafter as requested by the Company, the Optionee hereby authorizes withholding from payroll and any other amounts payable to the Optionee, and otherwise agrees to make adequate provision for
(including by means of a Cashless Exercise to the extent permitted by the Company), any sums required to satisfy the federal, state, local and foreign tax withholding obligations of the Company, if any, which arise in connection with the Option,
including, without limitation, obligations arising upon (i) the exercise, in whole or in part, of the Option, (ii) the transfer, in whole or in part, of any shares acquired upon exercise of the Option, (iii) the operation of any law
or regulation providing for the imputation of interest, or (iv) the lapsing of any restriction with respect to any shares acquired upon exercise of the Option. The Option is not exercisable unless the tax withholding obligations with respect to
the Option are satisfied. Accordingly, the Company shall have no obligation to deliver shares of Stock or to release shares of Stock from an escrow established pursuant to the Option until the tax withholding obligations relating to the Option have
been satisfied by the Optionee. 
 4.5 Certificate Registration.    The
certificate for the shares as to which the Option is exercised shall be registered in the name of the Optionee, or, if applicable, in the names of the heirs of the Optionee. 

4.6 Restrictions on Grant of the Option and Issuance of Shares.  The grant of the Option and the issuance of
shares of Stock upon exercise of the Option shall be subject to compliance with all applicable requirements of federal, state or foreign law with respect to such securities. The Option may not be exercised if the issuance of shares of Stock upon
exercise would constitute a violation of any applicable federal, state or foreign securities laws or other law or regulations or the requirements of any stock exchange or market system upon which the Stock may then be listed. In addition, the Option
may not be exercised unless (i) a registration statement under the Securities Act shall at the time of exercise of the Option be in effect with respect to the shares issuable upon exercise of the Option or (ii) in the opinion of legal
counsel to the Company, the shares issuable upon exercise of the Option may be issued in accordance with the terms of an applicable exemption from the registration requirements of the Securities Act. THE OPTIONEE IS CAUTIONED THAT THE OPTION MAY NOT
BE EXERCISED UNLESS THE FOREGOING CONDITIONS ARE SATISFIED. ACCORDINGLY, THE OPTIONEE MAY NOT BE ABLE TO EXERCISE THE OPTION WHEN DESIRED EVEN THOUGH THE OPTION IS VESTED. The inability of the Company to obtain from any regulatory body having
jurisdiction the authority, if any, deemed by the Company’s legal counsel to be necessary to the lawful issuance and sale of any shares subject to the Option shall relieve the Company of any liability in respect of the failure to issue or sell
such shares as to which such requisite authority shall not have been obtained. As a condition to the exercise of the Option, the Company may require the Optionee to satisfy any qualifications that may be necessary or appropriate, to evidence
compliance with any applicable law or regulation and to make any representation or warranty with respect thereto as may be requested by the Company. 

  
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 4.7 Fractional Shares.  The Company
shall not be required to issue fractional shares upon the exercise of the Option. 
 5.
   NONTRANSFERABILITY OF THE OPTION. 

The Option may be exercised during the lifetime of the Optionee only by the Optionee or the Optionee’s guardian or legal
representative and may not be assigned or transferred in any manner except by will or by the laws of descent and distribution. Following the death of the Optionee, the Option, to the extent provided in Section 7, may be exercised by the
Optionee’s legal representative or by any person empowered to do so under the deceased Optionee’s will or under the then applicable laws of descent and distribution. 

6.    TERMINATION OF THE OPTION. 

The Option shall terminate and may no longer be exercised after the first to occur of (a) the Option Expiration Date,
(b) the last date for exercising the Option following termination of the Optionee’s Service as described in Section 7, or (c) a Change in Control to the extent provided in Section 8. 

7.    EFFECT OF TERMINATION OF
SERVICE. 
 7.1 Option Exercisability. 

(a) Disability.     If the Optionee’s Service terminates
because of the disability of the Optionee, the Option, to the extent unexercised and exercisable on the date on which the Optionee’s Service terminated, may be exercised by the Optionee (or the Optionee’s guardian or legal representative)
at any time prior to the expiration of twelve (12) months after the date on which the Optionee’s Service terminated, but in any event no later than the Option Expiration Date. 

(b) Death.  If the Optionee’s Service terminates because of the death of
the Optionee, the Option, to the extent unexercised and exercisable on the date on which the Optionee’s Service terminated, may be exercised by the Optionee’s legal representative or other person who acquired the right to exercise the
Option by reason of the Optionee’s death at any time prior to the expiration of twelve (12) months after the date on which the Optionee’s Service terminated, but in any event no later than the Option Expiration Date. The
Optionee’s Service shall be deemed to have terminated on account of death if the Optionee dies within three (3) months after the Optionee’s termination of Service. 

(c) [Termination After Change in Control.    If the Optionee’s Service ceases as a
result of Termination After Change in Control (as defined below), (i) the Option, to the extent unexercised and exercisable on the date on which the Optionee’s Service terminated, may be exercised by the Optionee (or the Optionee’s
guardian or legal representative) at any time prior to the expiration of six (6) months after the date on which the Optionee’s Service terminated, but in any event no later than the Option Expiration Date, and (ii) fifty percent
(50%) of the shares, if any, that are unvested as of the date of the Optionee’s termination of Service shall become immediately vested and exercisable.] 

  
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 (d) Other Termination of Service.  If the
Optionee’s Service terminates for any reason, except disability, death [or Termination After Change in Control], the Option, to the extent unexercised and exercisable by the Optionee on the date on which the Optionee’s Service terminated,
may be exercised by the Optionee at any time prior to the expiration of three (3) months (or such longer period of time as determined by the Administrator, in its discretion) after the date on which the Optionee’s Service terminated, but
in any event no later than the Option Expiration Date. 
 7.2 Extension if Exercise Prevented by
Law.  Notwithstanding the foregoing, if the exercise of the Option within the applicable time periods set forth in Section 7.1 is prevented by the provisions of Section 4.6, the Option shall remain
exercisable until three (3) months after the date the Optionee is notified by the Company that the Option is exercisable, but in any event no later than the Option Expiration Date. 

7.3 Extension if Optionee Subject to Section 16(b).    Notwithstanding the foregoing, if a
sale within the applicable time periods set forth in Section 7.1 of shares acquired upon the exercise of the Option would subject the Optionee to suit under Section 16(b) of the Exchange Act, the Option shall remain exercisable until the
earliest to occur of (i) the tenth (10th) day following the date on which a sale of such shares by the Optionee would no longer be subject to such suit, (ii) the one hundred and ninetieth (190th) day after the Optionee’s
termination of Service, or (iii) the Option Expiration Date. 
 7.4 Certain Definitions. 

(a) [“Termination After Change in Control” shall mean either of the following events occurring within twelve
(12) months after a Change in Control: 
 (i)         termination by the
Company of the Optionee’s Service with the Company for any reason other than for Cause (as defined below); or 
 (ii)
       [the Optionee’s resignation for Good Reason (as defined below) from all capacities in which the Optionee is then rendering Service to the Company within a reasonable period of time following the event
constituting Good Reason.] 
 Notwithstanding any provision herein to the contrary, Termination After Change in Control shall not include
any termination of the Optionee’s Service with the Company that (1) is for Cause (as defined below); (2) is a result of the Optionee’s death or disability; (3) is a result of the Optionee’s voluntary termination of
Service [other than for Good Reason]; or (4) occurs prior to the effectiveness of a Change in Control.] 
 (b)
“Cause” shall have the meaning set forth in the Optionee’s employment agreement with the Company, if any, or in the absence of such employment agreement or definition, shall mean any of the following: (i) the
Optionee’s theft, dishonesty, or falsification of any Company documents or records; (ii) the Optionee’s improper use or disclosure of the Company’s confidential or proprietary information; (iii) any action by the Optionee
which has a detrimental effect on the Company’s reputation or business; (iv) the Optionee’s failure or inability to perform any reasonable assigned duties after written notice 

  
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from the Company of, and a reasonable opportunity to cure, such failure or inability; (v) any material breach by the Optionee of any employment agreement between the Optionee and the
Company, which breach is not cured pursuant to the terms of such agreement; or (vi) the Optionee’s conviction (including any plea of guilty or nolo contendere) of any criminal act which impairs the Optionee’s ability to perform his or
her duties with the Company. 
 (c) [“Good Reason” shall have the meaning set forth in the Optionee’s
employment agreement with the Company, if any, or in the absence of such employment agreement or definition, shall mean any one or more of the following: 

(i)        without the Optionee’s express written consent, the assignment to the
Optionee of any duties, or any limitation of the Optionee’s responsibilities, substantially inconsistent with the Optionee’s positions, duties, responsibilities and status with the Company immediately prior to the date of the Change in
Control; 
 (ii)       without the Optionee’s express written consent, the relocation of
the principal place of the Optionee’s Service to a location that is more than fifty (50) miles from the Optionee’s principal place of Service immediately prior to the date of the Change in Control, or the imposition of travel
requirements substantially more demanding of the Optionee than such travel requirements existing immediately prior to the date of the Change in Control; 

(iii)       any failure by the Company to pay, or any material reduction by the Company of,
(1) the Optionee’s base salary in effect immediately prior to the date of the Change in Control (unless reductions comparable in amount and duration are concurrently made for all other employees of the Company with responsibilities,
organizational level and title comparable to the Optionee’s), or (2) the Optionee’s bonus compensation, if any, in effect immediately prior to the date of the Change in Control (subject to applicable performance requirements with
respect to the actual amount of bonus compensation earned by the Optionee); or 
 (iv)
      any failure by the Company to (1) continue to provide the Optionee with the opportunity to participate, on terms no less favorable than those in effect for the benefit of any employee or service provider
group which customarily includes a person holding the employment or service provider position or a comparable position with the Company then held by the Optionee, in any benefit or compensation plans and programs, including, but not limited to, the
Company’s life, disability, health, dental, medical, savings, profit sharing, stock purchase and retirement plans, if any, in which the Optionee was participating immediately prior to the date of the Change in Control, or their equivalent, or
(2) provide the Optionee with all other fringe benefits (or their equivalent) from time to time in effect for the benefit of any employee or service provider group which customarily includes a person holding the employment or service provider
position or a comparable position with the Company then held by the Optionee.] 

  
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 8.    CHANGE IN
CONTROL. 
 In the event of a Change in Control, the surviving, continuing, successor,
or purchasing corporation or other business entity or parent thereof, as the case may be (the “Acquiring Corporation”), may, without the consent of the Optionee, either assume the Company’s rights and obligations under the
Option or substitute for the Option a substantially equivalent option for the Acquiring Corporation’s stock. In the event the Acquiring Corporation elects not to assume the Company’s rights and obligations under the Option or substitute
for the Option in connection with the Change in Control, the Option, to the extent not previously exercised, shall terminate and cease to be outstanding effective as of the date of the Change in Control. Notwithstanding the foregoing, shares
acquired upon exercise of the Option prior to the Change in Control and any consideration received pursuant to the Change in Control with respect to such shares shall continue to be subject to all applicable provisions of this Option Agreement
except as otherwise provided herein. Furthermore, notwithstanding the foregoing, if the corporation the stock of which is subject to the Option immediately prior to an Ownership Change Event constituting a Change in Control is the surviving or
continuing corporation and immediately after such Ownership Change Event less than fifty percent (50%) of the total combined voting power of its voting stock is held by another corporation or by other corporations that are members of an
affiliated group within the meaning of Section 1504(a) of the Code without regard to the provisions of Section 1504(b) of the Code, the Option shall not terminate unless the Administrator otherwise provides in its discretion. 

9.    ADJUSTMENTS FOR CHANGES IN CAPITAL
STRUCTURE. 
 In the event of any stock dividend, stock split, reverse stock split,
recapitalization, combination, reclassification, or similar change in the capital structure of the Company, including an Equity Restructuring, appropriate adjustments shall be made in the number, Exercise Price and class of shares of stock subject
to the Option, as determined by the Administrator pursuant to Section 9 of the Plan. If a majority of the shares which are of the same class as the shares that are subject to the Option are exchanged for, converted into, or otherwise become
(whether or not pursuant to an Ownership Change Event) shares of another corporation (the “New Shares”), the Administrator may unilaterally amend the Option to provide that the Option is exercisable for New Shares. In the event of
any such amendment, the Number of Option Shares and the Exercise Price shall be adjusted in a fair and equitable manner, as determined by the Administrator, in its discretion. Notwithstanding the foregoing, any fractional share resulting from an
adjustment pursuant to this Section 9 shall be rounded down to the nearest whole number, and in no event may the Exercise Price be decreased to an amount less than the par value, if any, of the stock subject to the Option. The adjustments
determined by the Administrator shall be final, binding and conclusive. 
 10. RIGHTS AS
A STOCKHOLDER, EMPLOYEE OR CONSULTANT. 

The Optionee shall have no rights as a stockholder with respect to any shares covered by the Option until the date of the
issuance of a certificate for the shares for which the Option has been exercised (as evidenced by the appropriate entry on the books of the Company or of a duly authorized transfer agent of the Company). No adjustment shall be made for dividends,
distributions or other rights for which the record date is prior to the date such certificate is issued, 

  
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except as provided in Section 9. If the Optionee is an Employee, the Optionee understands and acknowledges that, except as otherwise provided in a separate, written employment agreement
between the Company and the Optionee, the Optionee’s employment is “at will” and is for no specified term. Nothing in this Option Agreement shall confer upon the Optionee any right to continue in the service of the Company or
interfere in any way with any right of the Company to terminate the Optionee’s Service as an Employee or Consultant, as the case may be, at any time. 

11. RIGHT OF FIRST REFUSAL. 

11.1      Grant of Right of First Refusal.    Except
as provided in Section 11.7 below, in the event the Optionee, the Optionee’s legal representative, or other holder of shares acquired upon exercise of the Option proposes to sell, exchange, transfer, pledge, or otherwise dispose of any
shares acquired upon exercise of the Option (the “Transfer Shares”) to any person or entity, including, without limitation, any stockholder of the Company, the Company shall have the right to repurchase the Transfer Shares under the
terms and subject to the conditions set forth in this Section 11 (the “Right of First Refusal”). 

11.2      Notice of Proposed Transfer.    Prior to
any proposed transfer of the Transfer Shares, the Optionee shall deliver written notice (the “Transfer Notice”) to the Company describing fully the proposed transfer, including the number of Transfer Shares, the name and address of
the proposed transferee (the “Proposed Transferee”) and, if the transfer is voluntary, the proposed transfer price, and containing such information necessary to show the bona fide nature of the proposed transfer. In the event of a
bona fide gift or involuntary transfer, the proposed transfer price shall be deemed to be the Fair Market Value of the Transfer Shares, as determined by the Administrator in good faith. If the Optionee proposes to transfer any Transfer Shares to
more than one Proposed Transferee, the Optionee shall provide a separate Transfer Notice for the proposed transfer to each Proposed Transferee. The Transfer Notice shall be signed by both the Optionee and the Proposed Transferee and must constitute
a binding commitment of the Optionee and the Proposed Transferee for the transfer of the Transfer Shares to the Proposed Transferee subject only to the Right of First Refusal. 

11.3      Bona Fide Transfer.    If the Company
determines that the information provided by the Optionee in the Transfer Notice is insufficient to establish the bona fide nature of a proposed voluntary transfer, the Company shall give the Optionee written notice of the Optionee’s failure to
comply with the procedure described in this Section 11, and the Optionee shall have no right to transfer the Transfer Shares without first complying with the procedure described in this Section 11. The Optionee shall not be permitted to
transfer the Transfer Shares if the proposed transfer is not bona fide. 
 11.4      Exercise
of Right of First Refusal.    If the Company determines the proposed transfer to be bona fide, the Company shall have the right to purchase all, but not less than all, of the Transfer Shares (except as
the Company and the Optionee otherwise agree) at the purchase price and on the terms set forth in the Transfer Notice by delivery to the Optionee of a notice of exercise of the Right of First Refusal within thirty (30) days after the date the
Transfer Notice is delivered to the Company. The Company’s exercise or failure to exercise the Right of First Refusal with respect to any proposed transfer described in a Transfer Notice shall not affect the Company’s right to exercise the
Right of First Refusal with respect to any proposed transfer 

  
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described in any other Transfer Notice, whether or not such other Transfer Notice is issued by the Optionee or issued by a person other than the Optionee with respect to a proposed transfer to
the same Proposed Transferee. If the Company exercises the Right of First Refusal, the Company and the Optionee shall thereupon consummate the sale of the Transfer Shares to the Company on the terms set forth in the Transfer Notice within sixty
(60) days after the date the Transfer Notice is delivered to the Company (unless a longer period is offered by the Proposed Transferee); provided, however, that in the event the Transfer Notice provides for the payment for the Transfer Shares
other than in cash, the Company shall have the option of paying for the Transfer Shares by the present value cash equivalent of the consideration described in the Transfer Notice as reasonably determined by the Company. For purposes of the
foregoing, cancellation of any indebtedness of the Optionee to the Company shall be treated as payment to the Optionee in cash to the extent of the unpaid principal and any accrued interest canceled. 

11.5      Failure to Exercise Right of First Refusal.   If the
Company fails to exercise the Right of First Refusal in full (or to such lesser extent as the Company and the Optionee otherwise agree) within the period specified in Section 11.4 above, the Optionee may conclude a transfer to the Proposed
Transferee of the Transfer Shares on the terms and conditions described in the Transfer Notice, provided such transfer occurs not later than ninety (90) days following delivery to the Company of the Transfer Notice. The Company shall have the
right to demand further assurances from the Optionee and the Proposed Transferee (in a form satisfactory to the Company) that the transfer of the Transfer Shares was actually carried out on the terms and conditions described in the Transfer Notice.
No Transfer Shares shall be transferred on the books of the Company until the Company has received such assurances, if so demanded, and has approved the proposed transfer as bona fide. Any proposed transfer on terms and conditions different from
those described in the Transfer Notice, as well as any subsequent proposed transfer by the Optionee, shall again be subject to the Right of First Refusal and shall require compliance by the Optionee with the procedure described in this
Section 11. 
 11.6      Transferees of Transfer
Shares.   All transferees of the Transfer Shares or any interest therein, other than the Company, shall be required as a condition of such transfer to agree in writing (in a form satisfactory to the Company) that
such transferee shall receive and hold such Transfer Shares or interest therein subject to all of the terms and conditions of this Option Agreement, including this Section 11 providing for the Right of First Refusal with respect to any
subsequent transfer. Any sale or transfer of any shares acquired upon exercise of the Option shall be void unless the provisions of this Section 11 are met. 

11.7      Transfers Not Subject to Right of First Refusal.   The
Right of First Refusal shall not apply to any transfer or exchange of the shares acquired upon exercise of the Option if such transfer or exchange is in connection with an Ownership Change Event. If the consideration received pursuant to such
transfer or exchange consists of stock of the Company, such consideration shall remain subject to the Right of First Refusal unless the provisions of Section 11.9 below result in a termination of the Right of First Refusal. 

11.8      Assignment of Right of First Refusal.  The Company shall have the right
to assign the Right of First Refusal at any time, whether or not there has been an attempted transfer, to one or more persons as may be selected by the Company. 

  
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 11.9      Early Termination of Right of First
Refusal.    The other provisions of this Option Agreement notwithstanding, the Right of First Refusal shall terminate and be of no further force and effect upon (a) the occurrence of a Change in Control,
unless the Acquiring Corporation assumes the Company’s rights and obligations under the Option or substitutes a substantially equivalent option for the Acquiring Corporation’s stock for the Option, or (b) the existence of a public
market for the class of shares subject to the Right of First Refusal. A “public market” shall be deemed to exist if (i) such stock is listed on a national securities exchange (as that term is used in the Exchange Act) or
(ii) such stock is traded on the over-the-counter market and prices therefor are published daily on business days in a recognized financial journal. 

12. VESTED SHARE REPURCHASE OPTION. 

12.1      Grant of Vested Share Repurchase
Option.    Except as provided in Section 12.4 below, in the event of the termination of the Optionee’s Service with the Company at any time for Cause (as defined in Section 7.4(b)), the Company
shall have the right to repurchase the shares acquired by the Optionee pursuant to the Option which are Vested Shares (the “Repurchase Shares”) under the terms and subject to the conditions set forth in this Section 12 (the
“Vested Share Repurchase Option”). 
 12.2      Exercise of Vested Share
Repurchase Option.    The Company may exercise the Vested Share Repurchase Option by written notice to the Optionee or other holder of the Repurchase Shares, as the case may be, during the Repurchase Period. The
“Repurchase Period” shall be the period commencing at the time set forth in Section 12.1 above and ending on the later of (a) the date ninety (90) days after the commencement of the Repurchase Period or (b) the
date ninety (90) days after the Option is last exercised. If the Company fails to give notice during the Repurchase Period, the Vested Share Repurchase Option shall terminate (unless the Company and the Optionee have extended the time for the
exercise of the Vested Share Repurchase Option) unless and until there is a subsequent Repurchase Event. Notwithstanding a termination of the Vested Share Repurchase Option, the remaining provisions of this Option Agreement shall remain in full
force and effect, including, without limitation, the Right of First Refusal set forth in Section 11. The Vested Share Repurchase Option must be exercised, if at all, for all of the Repurchase Shares, except as the Company and the Optionee
otherwise agree. 
 12.3      Payment for Repurchase
Shares.    The repurchase price per share being repurchased by the Company pursuant to the Vested Share Repurchase Option shall be an amount equal to the Fair Market Value of the shares determined as of the date of the
Repurchase Event by the Administrator in good faith. Payment by the Company to the Optionee shall be made in cash on or before the last day of the Repurchase Period. 

12.4      Transfers Not Subject to Vested Share Repurchase Option.    The
Vested Share Repurchase Option shall not apply to any transfer or exchange of shares acquired upon exercise of the Option if such transfer or exchange is in connection with an Ownership Change Event. If the consideration received pursuant to such
transfer or exchange consists of stock of the Company, such consideration will remain subject to the Vested Share Repurchase 

  
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Option unless the provisions of Section 12.6 below result in a termination of the Vested Share Repurchase Option. 

12.5     Assignment of Vested Share Repurchase Option.  The Company shall have the right
to assign the Vested Share Repurchase Option at any time, whether or not such option is then exercisable, to one or more persons as may be selected by the Company. 

12.6      Early Termination of Vested Share Repurchase Option.    The
other provisions of this Option Agreement notwithstanding, the Vested Share Repurchase Option shall terminate and be of no further force and effect upon (a) the occurrence of a Change in Control, unless the Acquiring Corporation assumes the
Company’s rights and obligations under the Option or substitutes a substantially equivalent option for the Acquiring Corporation’s stock for the Option, or (b) the existence of a public market, as defined in Section 11.9, for the
class of shares subject to the Vested Share Repurchase Option. 
 13. ESCROW.

 13.1      Establishment of Escrow.  To ensure that
shares subject to the Right of First Refusal or the Vested Share Repurchase Option will be available for repurchase, the Company may require the Optionee to deposit the certificate evidencing the shares which the Optionee purchases upon exercise of
the Option with an agent designated by the Company under the terms and conditions of an escrow agreement approved by the Company. If the Company does not require such deposit as a condition of exercise of the Option, the Company reserves the right
at any time to require the Optionee to so deposit the certificate in escrow. Upon the occurrence of an Ownership Change Event or a change, as described in Section 9, in the character or amount of any of the outstanding stock of the corporation
the stock of which is subject to the provisions of this Option Agreement, any and all new, substituted or additional securities or other property to which the Optionee is entitled by reason of the Optionee’s ownership of shares of Stock
acquired upon exercise of the Option that remain, following such Ownership Change Event or change described in Section 9, subject to the Right of First Refusal or Vested Share Repurchase Option, shall be immediately subject to the escrow to the
same extent as such shares of Stock immediately before such event. The Company shall bear the expenses of the escrow. 

13.2      Delivery of Shares to Optionee.  As soon as
practicable after the expiration of the Right of First Refusal and the Vested Share Repurchase Option, but not more frequently than twice each calendar year, the escrow agent shall deliver to the Optionee the shares and any other property no longer
subject to such restrictions. 
 13.3      Notices and Payments.  In the event
the shares and any other property held in escrow are subject to the Company’s exercise of the Right of First Refusal or the Vested Share Repurchase Option, the notices required to be given to the Optionee shall be given to the escrow agent, and
any payment required to be given to the Optionee shall be given to the escrow agent. Within thirty (30) days after payment by the Company, the escrow agent shall deliver the shares and any other property which the Company has purchased to the
Company and shall deliver the payment received from the Company to the Optionee. 

  
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 14. STOCK DISTRIBUTIONS SUBJECT
TO OPTION AGREEMENT. 
 If, from time to time, there is
any stock dividend, stock split or other change, including an Equity Restructuring, as described in Section 9, in the character or amount of any of the outstanding stock of the corporation the stock of which is subject to the provisions of this
Option Agreement, then in such event any and all new, substituted or additional securities to which the Optionee is entitled by reason of the Optionee’s ownership of the shares acquired upon exercise of the Option shall be immediately subject
to the Right of First Refusal and Vested Share Repurchase Option with the same force and effect as the shares subject to the Right of First Refusal and Vested Share Repurchase Option immediately before such event. 

15. NOTICE OF SALES UPON DISQUALIFYING
DISPOSITION. 
 The Optionee shall dispose of the shares acquired pursuant to the
Option only in accordance with the provisions of this Option Agreement. In addition, if the Notice designates this Option as an Incentive Stock Option, the Optionee shall (a) promptly notify the President of the Company if the Optionee
disposes of any of the shares acquired pursuant to the Option within one (1) year after the date the Optionee exercises all or part of the Option or within two (2) years after the Date of Option Grant and (b) provide the Company with
a description of the circumstances of such disposition. Until such time as the Optionee disposes of such shares in a manner consistent with the provisions of this Option Agreement, unless otherwise expressly authorized by the Company, the Optionee
shall hold all shares acquired pursuant to the Option in the Optionee’s name (and not in the name of any nominee) for the one-year period immediately after the exercise of the Option and the two-year period immediately after Date of Option
Grant. At any time during the one-year or two-year periods set forth above, the Company may place a legend on any certificate representing shares acquired pursuant to the Option requesting the transfer agent for the Company’s stock to notify
the Company of any such transfers. The obligation of the Optionee to notify the Company of any such transfer shall continue notwithstanding that a legend has been placed on the certificate pursuant to the preceding sentence. 

16. LEGENDS. 

The Company may at any time place legends referencing the Right of First Refusal or the Vested Share Repurchase Option, and
any applicable federal, state or foreign securities law restrictions on all certificates representing shares of stock subject to the provisions of this Option Agreement. The Optionee shall, at the request of the Company, promptly present to the
Company any and all certificates representing shares acquired pursuant to the Option in the possession of the Optionee in order to carry out the provisions of this Section. Unless otherwise specified by the Company, legends placed on such
certificates may include, but shall not be limited to, the following: 
 16.1      “THE
SECURITIES EVIDENCED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT BE SOLD, TRANSFERRED, ASSIGNED OR HYPOTHECATED UNLESS THERE IS AN EFFECTIVE REGISTRATION STATEMENT UNDER SUCH ACT COVERING
SUCH SECURITIES, THE SALE IS MADE IN ACCORDANCE WITH RULE 

  
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144 OR RULE 701 UNDER THE ACT, OR THE COMPANY RECEIVES AN OPINION OF COUNSEL REASONABLY SATISFACTORY TO THE COMPANY, STATING THAT SUCH SALE, TRANSFER, ASSIGNMENT OR HYPOTHECATION IS EXEMPT
FROM THE REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS OF SUCH ACT.” 
 16.2
     “THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO A RIGHT OF FIRST REFUSAL OPTION AND VESTED SHARE REPURCHASE OPTION IN FAVOR OF THE CORPORATION OR ITS ASSIGNEE SET FORTH IN AN AGREEMENT BETWEEN THE
CORPORATION AND THE REGISTERED HOLDER, OR SUCH HOLDER’S PREDECESSOR IN INTEREST, A COPY OF WHICH IS ON FILE AT THE PRINCIPAL OFFICE OF THIS CORPORATION.” 

16.3      “THE SHARES EVIDENCED BY THIS CERTIFICATE WERE ISSUED BY THE CORPORATION TO THE
REGISTERED HOLDER UPON EXERCISE OF AN INCENTIVE STOCK OPTION AS DEFINED IN SECTION 422 OF THE INTERNAL REVENUE CODE OF 1986, AS AMENDED (“ISO”). IN ORDER TO OBTAIN THE PREFERENTIAL TAX TREATMENT AFFORDED TO ISOs, THE SHARES
SHOULD NOT BE TRANSFERRED PRIOR TO [INSERT DISQUALIFYING DISPOSITION DATE HERE]. SHOULD THE REGISTERED HOLDER ELECT TO TRANSFER ANY OF THE SHARES PRIOR TO THIS DATE AND FOREGO ISO TAX TREATMENT, THE TRANSFER AGENT FOR THE SHARES SHALL NOTIFY
THE CORPORATION IMMEDIATELY. THE REGISTERED HOLDER SHALL HOLD ALL SHARES PURCHASED UNDER THE INCENTIVE STOCK OPTION IN THE REGISTERED HOLDER’S NAME (AND NOT IN THE NAME OF ANY NOMINEE) PRIOR TO THIS DATE OR UNTIL TRANSFERRED AS DESCRIBED
ABOVE.” 
 17. LOCK-UP AGREEMENT. 

The Optionee hereby agrees that in the event of any underwritten public offering of stock, including an initial public
offering of stock, made by the Company pursuant to an effective registration statement filed under the Securities Act, the Optionee shall not offer, sell, contract to sell, pledge, hypothecate, grant any option to purchase or make any short sale of,
or otherwise dispose of any shares of stock of the Company or any rights to acquire stock of the Company for such period of time from and after the effective date of such registration statement as may be established by the underwriter for such
public offering; provided, however, that such period of time shall not exceed one hundred eighty (180) days from the effective date of the registration statement to be filed in connection with such public offering. The foregoing limitation
shall not apply to shares registered in the public offering under the Securities Act. 
 18. RESTRICTIONS
ON TRANSFER OF SHARES. 
 No shares
acquired upon exercise of the Option may be sold, exchanged, transferred (including, without limitation, any transfer to a nominee or agent of the Optionee), assigned, pledged, hypothecated or otherwise disposed of, including by operation of law, in
any manner which violates any of the provisions of this Option Agreement and any such attempted disposition shall be void. The Company shall not be required (a) to transfer on its books any shares which will have been transferred in violation
of any of the provisions set forth in this 

  
 15 

 Non-Executive Version 

 

 
Option Agreement or (b) to treat as owner of such shares or to accord the right to vote as such owner or to pay dividends to any transferee to whom such shares will have been so transferred.

 19. MISCELLANEOUS PROVISIONS. 

19.1      Binding Effect.  Subject to the restrictions on transfer set forth
herein, this Option Agreement shall inure to the benefit of and be binding upon the parties hereto and their respective heirs, executors, administrators, successors and assigns. 

19.2      Termination or Amendment.    The Administrator may terminate or
amend the Plan or the Option at any time; provided, however, that except as provided in Section 8 in connection with a Change in Control, no such termination or amendment may adversely affect the Option or any unexercised portion hereof without
the consent of the Optionee unless such termination or amendment is necessary to comply with any applicable law or government regulation or is required to enable the Option, if designated an Incentive Stock Option in the Notice, to qualify as an
Incentive Stock Option. No amendment or addition to this Option Agreement shall be effective unless in writing. 
 19.3
     Notices.  Any notice required or permitted hereunder shall be given in writing and shall be deemed effectively given (except to the extent that this Option Agreement provides for effectiveness only upon
actual receipt of such notice) upon personal delivery or upon deposit in the United States Post Office, by registered or certified mail, with postage and fees prepaid, addressed to the other party at the address shown below that party’s
signature or at such other address as such party may designate in writing from time to time to the other party. 
 19.4
     Integrated Agreement.  The Notice, this Option Agreement and the Plan constitute the entire understanding and agreement of the Optionee and the Company with respect to the subject matter contained
herein or therein and supersedes any prior agreements, understandings, restrictions, representations, or warranties among the Optionee and the Company with respect to such subject matter other than those as set forth or provided for herein or
therein. To the extent contemplated herein or therein, the provisions of the Notice and the Option Agreement shall survive any exercise of the Option and shall remain in full force and effect. 

19.5      Applicable Law.  This Option Agreement shall be governed by the laws of
the State of California as such laws are applied to agreements between California residents entered into and to be performed entirely within the State of California. 

19.6      Counterparts.   The Notice may be executed in counterparts, each of
which shall be deemed an original, but all of which together shall constitute one and the same instrument. 

  
 16 

					
	       Incentive Stock Option	  	Optionee:	  	  

	       Nonstatutory Stock Option	  		  	

					
		  	Date:	  	  

 STOCK OPTION EXERCISE NOTICE 

(STANDARD VESTING) 
  

			
	Ambrx, Inc.	 	
	Attention: Chief Business Officer	 	
	  
	 	
	  
	 	

 Ladies and Gentlemen: 

1.        Option.  I was granted an option (the
“Option”) to purchase shares of the common stock (the “Shares”) of Ambrx, Inc. (the “Company”) pursuant to the Company’s 2013 Equity Incentive Plan, as amended from time to time (the
“Plan”), my Notice of Grant of Stock Option (the “Notice”) and my Stock Option Agreement (the “Option Agreement”) as follows: 

 

					
	Grant Number:	 	  

	  
 Date of Option Grant:
	 	  

	  
 Number of Option Shares:
	 	  

	  
 Exercise Price per Share:
	 	$	 	  

 2.        Exercise of Option.  I
hereby elect to exercise the Option to purchase the following number of Shares: 
  

					
	Total Shares Purchased:	 	  

	  
 Total Exercise Price (Total Shares X Price per Share)
	 	$	 	  

 3.        Payments.  I enclose
payment in full of the total exercise price for the Shares in the following form(s), as authorized by my Option Agreement: 
  

							
	 ̈	 	Cash:	 	$	 	  

	 ̈	 	  
 Check:
	 	$	 	  

	 ̈	 	  
 Tender of Company Stock:
	 	Contact Plan Administrator

  
 1 

 4.        Tax
Withholding.  I authorize payroll withholding and otherwise will make adequate provision for the federal, state, local and foreign tax withholding obligations of the Company, if any, in connection with the Option. If I am
exercising a Nonstatutory Stock Option, I enclose payment in full of my withholding taxes, if any, as follows: 
 (Contact Plan
Administrator for amount of tax due.) 
  

							
	 ̈	 	Cash:	 	$	 	  

	 ̈	 	  
 Check:
	 	$	 	  

 5.        Optionee Information. 

 

			
	 My address is:	 	  

		
		 	  

 
			
		
	 My Social Security Number is:	 	  

 6.        Notice of Disqualifying
Disposition. If the Option is an Incentive Stock Option, I agree that I will promptly notify the President of the Company if I transfer any of the Shares within one (1) year from the date I exercise all or part of the Option or within
two (2) years of the Date of Option Grant. 
 7.        Binding
Effect. I agree that the Shares are being acquired in accordance with and subject to the terms, provisions and conditions of the Option Agreement, including the Right of First Refusal and Vested Share Repurchase Option set forth therein, to
all of which I hereby expressly assent. This Agreement shall inure to the benefit of and be binding upon my heirs, executors, administrators, successors and assigns. If required by the Company, I agree to deposit the certificate(s) evidencing the
Shares, along with a blank stock assignment separate from certificate executed by me, with an escrow agent designated by the Company, to be held pursuant to the Company’s standard Joint Escrow Instructions. 

8.        Transfer.  I understand and acknowledge that the Shares
have not been registered under the Securities Act of 1933, as amended (the “Securities Act”), and that consequently the Shares must be held indefinitely unless they are subsequently registered under the Securities Act, an exemption
from such registration is available, or they are sold in accordance with Rule 144 or Rule 701 under the Securities Act. I further understand and acknowledge that the Company is under no obligation to register the Shares. I understand that
the certificate or certificates evidencing the Shares will be imprinted with legends which prohibit the transfer of the Shares unless they are registered or such registration is not required in the opinion of legal counsel satisfactory to the
Company. 
 I am aware that Rule 144 under the Securities Act, which permits limited public resale of securities
acquired in a nonpublic offering, is not currently available with respect to the Shares and, in any event, is available only if certain conditions are satisfied. I understand that any sale of the Shares that might be made in reliance upon
Rule 144 may only be made in limited amounts in accordance with the terms and conditions of such rule and that a copy of Rule 144 will be delivered to me upon request. 

 

  
 2 

 I understand that I am purchasing the Shares pursuant to the terms of the Plan,
the Notice and my Option Agreement, copies of which I have received and carefully read and understand. 
  

			
	Very truly yours,	 	
		
	  
	 	
	(Signature)	 	

  

			
	Receipt of the above is hereby acknowledged.
	
	AMBRX, INC.
		
	By:	 	  

			
		
	Title:	 	  

			
		
	Dated:	 	  

  
 3 

 Executive Version 

AMBRX, INC. 
 NOTICE
OF GRANT OF STOCK OPTION 
 (Standard Vesting) 

[Name] (the “Optionee”) has been granted an option (the “Option”) to purchase
certain shares of Stock of Ambrx, Inc. pursuant to the Ambrx, Inc. 2013 Equity Incentive Plan, as amended from time to time (the “Plan”), as follows: 
  

			
	Option Grant Number:	  	
	  
 Date of Option Grant:
	  	
	  
 Number of Option Shares:
	  	
	  
 Exercise Price:
	  	 $[ l ] per share

	  
 Vesting Commencement Date:
	  	
	  
 Option Expiration Date:
	  	 The date ten (10) years after the Date of Option Grant

	  
 Tax Status of Option:
	  	  ̈          Incentive Stock
Option

		  	 ̈          Nonqualified Stock Option

 Vested Shares: Except as provided in the Stock Option Agreement, the number of
“Vested Shares” (disregarding any resulting fractional share) as of any date is determined by multiplying the Number of Option Shares by the “Vested Ratio” determined as of such date as follows: 

[Twenty Five percent (25%) of the total number of Option Shares subject to this Option shall vest on
the first anniversary of the Vesting Commencement Date (rounded up to the next whole number of shares) and 1/48th of the total number of Option Shares subject to this Option (rounded up to the
next whole number of shares) shall vest on each full month of the Optionee’s continuous Service thereafter (measured as of the day of the month corresponding to the Vesting Commencement Date), so that all of the Option Shares shall be vested on
the fourth (4th) anniversary of the Vesting Commencement Date (and, for purposes of clarification, any additional Option Shares remaining unvested on such date due to the foregoing rounding
shall vest on the fourth (4th) anniversary of the Vesting Commencement Date).] 

By their signatures below, the Company and the Optionee agree that the Option is governed by this Notice and by the
provisions of the Plan and the Stock Option Agreement, both of which are attached to and made a part of this document. The Optionee acknowledges receipt of copies of the Plan and the Stock Option Agreement, represents that the Optionee has read and
is familiar with their provisions, and hereby accepts the Option subject to all of their terms and conditions. 
  

							
	AMBRX, INC.	 		 	OPTIONEE
				
	By:	 	  
	 		 	  

		 		 		 	Signature
	Its:	 	 VP, Intellectual Property & Corporate Legal
	 		 	  

		 		 		 	Date
	   10975 North Torrey Pines Road
	 		 	  

	Address	 		 	Address
	   La Jolla, CA 92037
	 		 	  

 ATTACHMENTS:          2013 Equity Incentive Plan, Stock
Option Agreement and Exercise Notice 

  
 1 

 Executive Version 

 

 THE SECURITIES WHICH ARE THE SUBJECT OF THIS AGREEMENT HAVE NOT BEEN QUALIFIED WITH THE
COMMISSIONER OF CORPORATIONS OF THE STATE OF CALIFORNIA AND THE ISSUANCE OF SUCH SECURITIES OR THE PAYMENT OR RECEIPT OF ANY PART OF THE CONSIDERATION THEREFOR PRIOR TO SUCH QUALIFICATION IS UNLAWFUL, UNLESS THE SALE OF SECURITIES IS EXEMPT FROM
QUALIFICATION BY SECTION 25100, 25102, OR 25105 OF THE CALIFORNIA CORPORATIONS CODE. THE RIGHTS OF ALL PARTIES TO THIS AGREEMENT ARE EXPRESSLY CONDITIONED UPON SUCH QUALIFICATION BEING OBTAINED, UNLESS THE SALE IS SO EXEMPT. 

THE SECURITIES WHICH ARE THE SUBJECT OF THIS AGREEMENT HAVE BEEN ACQUIRED FOR INVESTMENT AND NOT WITH A VIEW TO, OR IN CONNECTION WITH, THE
SALE OR DISTRIBUTION THEREOF. NO SUCH SALE OR DISPOSITION MAY BE EFFECTED WITHOUT AN EFFECTIVE REGISTRATION STATEMENT RELATED THERETO OR AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED UNDER THE SECURITIES
ACT OF 1933. 
  
 AMBRX, INC. 

STOCK OPTION AGREEMENT 

(Standard Vesting) 

Ambrx, Inc. has granted to the individual (the “Optionee”) named in the Notice of Grant of Stock
Option (the “Notice”) to which this Stock Option Agreement (the “Option Agreement”) is attached an option (the “Option”) to purchase certain shares of Stock upon the terms and conditions set
forth in the Notice and this Option Agreement. The Option has been granted pursuant to and shall in all respects be subject to the terms and conditions of the Ambrx, Inc. 2013 Equity Incentive Plan, as amended from time to time (the
“Plan”), the provisions of which are incorporated herein by reference. By signing the Notice, the Optionee: (a) represents that the Optionee has received copies of, and has read and is familiar with the terms and conditions of,
the Notice, the Plan and this Option Agreement; (b) accepts the Option subject to all of the terms and conditions of the Notice, the Plan and this Option Agreement; and (c) agrees to accept as binding, conclusive and final all decisions or
interpretations of the Administrator upon any questions arising under the Notice, the Plan or this Option Agreement. 
 1.
     DEFINITIONS AND CONSTRUCTION. 

1.1 Definitions.  Unless otherwise defined herein, capitalized terms shall have the
meanings assigned to such terms in the Notice or the Plan. 
 1.2
Construction.  Captions and titles contained herein are for convenience only and shall not affect the meaning or interpretation of any provision of this Option Agreement. Except when otherwise indicated by the
context, the singular shall include the plural and the plural shall include the singular. Use of the term “or” is not intended to be exclusive, unless the context clearly requires otherwise. 

  
 2 

 Executive Version 

 

 2.      TAX
CONSEQUENCES. 
 2.1 Tax Status of
Option.     This Option is intended to have the tax status designated in the Notice. 

(a) Incentive Stock Option.    If the Notice so
designates, this Option is intended to be an Incentive Stock Option within the meaning of Section 422(b) of the Code to the maximum extent permitted, but the Company does not represent or warrant that this Option qualifies as such. The Optionee
should consult with the Optionee’s own tax advisor regarding the tax effects of this Option and the requirements necessary to obtain favorable income tax treatment under Section 422 of the Code, including, but not limited to, holding
period requirements. (NOTE TO OPTIONEE: If the Option is exercised more than three (3) months after the date on which you cease to be an Employee (other than by reason of your death or permanent and total disability as defined in
Section 22(e)(3) of the Code) or otherwise ceases to qualify as an Incentive Stock Option, the Option will be treated as a Nonstatutory Stock Option and not as an Incentive Stock Option to the extent required by Section 422 of the Code.)

 (b) Nonstatutory Stock Option.  If the Notice so designates, this Option is intended to be a
Nonstatutory Stock Option and shall not be treated as an Incentive Stock Option within the meaning of Section 422(b) of the Code. 

2.2 ISO Fair Market Value Limitation.  If the Notice designates this Option as an Incentive Stock
Option, then to the extent that the Option (together with all Incentive Stock Options granted to the Optionee under all stock option plans of the Company, including the Plan) becomes exercisable for the first time during any calendar year for
shares having a Fair Market Value greater than one hundred thousand dollars ($100,000), the portion of such options which exceeds such amount will be treated as Nonstatutory Stock Options. For purposes of this Section 2.2, options designated as
Incentive Stock Options are taken into account in the order in which they were granted, and the Fair Market Value of stock is determined as of the time the option with respect to such stock is granted. If the Code is amended to provide for a
different limitation from that set forth in this Section 2.2, such different limitation shall be deemed incorporated herein effective as of the date required or permitted by such amendment to the Code. If the Option is treated as an Incentive
Stock Option in part and as a Nonstatutory Stock Option in part by reason of the limitation set forth in this Section 2.2, the Optionee may designate which portion of such Option the Optionee is exercising. In the absence of such designation,
the Optionee shall be deemed to have exercised the Incentive Stock Option portion of the Option first. Separate certificates representing each such portion shall be issued upon the exercise of the Option. (NOTE TO OPTIONEE: If the aggregate Exercise
Price of the Option (that is, the Exercise Price multiplied by the Number of Option Shares) plus the aggregate exercise price of any other Incentive Stock Options you hold (whether granted pursuant to the Plan or any other stock option plan of the
Company) is greater than $100,000, you should contact the President of the Company to ascertain whether the entire Option qualifies as an Incentive Stock Option.) 

  
 3 

 Executive Version 

 

 3.   ADMINISTRATION. 

All questions of interpretation concerning this Option Agreement shall be determined by the Administrator. All
determinations by the Administrator shall be final and binding upon all persons having an interest in the Option. Any officer of the Company shall have the authority to act on behalf of the Company with respect to any matter, right, obligation, or
election which is the responsibility of or which is allocated to the Company herein, provided, the officer has apparent authority with respect to such matter, right, obligation, or election. 

4.   EXERCISE OF THE OPTION. 

4.1 Right to Exercise.  Except as otherwise provided herein, the Option shall be exercisable on and after
the Vesting Commencement Date and prior to the termination of the Option (as provided in Section 6) in an amount not to exceed the number of Vested Shares less the number of shares previously acquired upon exercise of the Option, subject to the
Company’s repurchase rights set forth in Sections 11 and 12. In no event shall the Option be exercisable for more shares than the Number of Option Shares. [The Option may also vest on an accelerated basis pursuant to that certain Executive
Employment Agreement dated as of [                    ], between the Optionee and the Company (as amended to date, the “Employment
Agreement”).] 
 4.2 Method of Exercise.  Exercise of the Option shall be
by written notice to the Company which must state the election to exercise the Option, the number of whole shares of Stock for which the Option is being exercised and such other representations and agreements as to the Optionee’s investment
intent with respect to such shares as may be required pursuant to the provisions of this Option Agreement. The written notice must be signed by the Optionee and must be delivered in person, by certified or registered mail, return receipt requested,
by confirmed facsimile transmission, or by such other means as the Company may permit, to the President of the Company, or other authorized representative of the Company, prior to the termination of the Option as set forth in Section 6,
accompanied by (i) full payment of the aggregate Exercise Price for the number of shares of Stock being purchased and (ii) an executed copy, if required herein, of the then current form of escrow agreement referenced below. The Option
shall be deemed to be exercised upon receipt by the Company of such written notice, the aggregate Exercise Price, and, if required by the Company, such executed agreement. 

4.3 Payment of Exercise Price. 

(a) Forms of Consideration Authorized.  Except as otherwise provided below,
payment of the aggregate Exercise Price for the number of shares of Stock for which the Option is being exercised shall be made (i) in cash, by check, or cash equivalent, (ii) by tender to the Company, or attestation to the ownership, of
whole shares of Stock owned by the Optionee having a Fair Market Value not less than the aggregate Exercise Price, (iii) by means of a Cashless Exercise, unless the Company, in its sole discretion, determines to terminate or decline to approve
any such program or procedure, or (iv) by any combination of the foregoing. 
 (b) Tender of
Stock.  Notwithstanding the foregoing, the Option may not be exercised by tender to the Company, or attestation to the ownership, of shares of Stock to the extent such tender or attestation would constitute a
violation of the provisions of any law, 

  
 4 

 Executive Version 

 

 
regulation or agreement restricting the redemption of the Company’s stock. The Option may not be exercised by tender to the Company, or attestation to the ownership, of shares of Stock
unless such shares either have been owned by the Optionee for more than six (6) months (and not used for another option exercise by attestation during such period) or were not acquired, directly or indirectly, from the Company. 

4.4 Tax Withholding.  At the time the Option is exercised, in whole or in part, or at
any time thereafter as requested by the Company, the Optionee hereby authorizes withholding from payroll and any other amounts payable to the Optionee, and otherwise agrees to make adequate provision for (including by means of a Cashless Exercise to
the extent permitted by the Company), any sums required to satisfy the federal, state, local and foreign tax withholding obligations of the Company, if any, which arise in connection with the Option, including, without limitation, obligations
arising upon (i) the exercise, in whole or in part, of the Option, (ii) the transfer, in whole or in part, of any shares acquired upon exercise of the Option, (iii) the operation of any law or regulation providing for the imputation
of interest, or (iv) the lapsing of any restriction with respect to any shares acquired upon exercise of the Option. The Option is not exercisable unless the tax withholding obligations with respect to the Option are satisfied. Accordingly, the
Company shall have no obligation to deliver shares of Stock or to release shares of Stock from an escrow established pursuant to the Option until the tax withholding obligations relating to the Option have been satisfied by the Optionee. 

4.5 Certificate Registration.    The certificate for the shares as to which
the Option is exercised shall be registered in the name of the Optionee, or, if applicable, in the names of the heirs of the Optionee. 

4.6 Restrictions on Grant of the Option and Issuance of Shares.  The grant of the
Option and the issuance of shares of Stock upon exercise of the Option shall be subject to compliance with all applicable requirements of federal, state or foreign law with respect to such securities. The Option may not be exercised if the issuance
of shares of Stock upon exercise would constitute a violation of any applicable federal, state or foreign securities laws or other law or regulations or the requirements of any stock exchange or market system upon which the Stock may then be listed.
In addition, the Option may not be exercised unless (i) a registration statement under the Securities Act shall at the time of exercise of the Option be in effect with respect to the shares issuable upon exercise of the Option or (ii) in
the opinion of legal counsel to the Company, the shares issuable upon exercise of the Option may be issued in accordance with the terms of an applicable exemption from the registration requirements of the Securities Act. THE OPTIONEE IS CAUTIONED
THAT THE OPTION MAY NOT BE EXERCISED UNLESS THE FOREGOING CONDITIONS ARE SATISFIED. ACCORDINGLY, THE OPTIONEE MAY NOT BE ABLE TO EXERCISE THE OPTION WHEN DESIRED EVEN THOUGH THE OPTION IS VESTED. The inability of the Company to obtain from any
regulatory body having jurisdiction the authority, if any, deemed by the Company’s legal counsel to be necessary to the lawful issuance and sale of any shares subject to the Option shall relieve the Company of any liability in respect of the
failure to issue or sell such shares as to which such requisite authority shall not have been obtained. As a condition to the exercise of the Option, the Company may require the Optionee to satisfy any qualifications that may be necessary or
appropriate, to evidence compliance with any applicable law or regulation and to make any representation or warranty with respect thereto as may be requested by the Company. 

  
 5 

 Executive Version 

 

 4.7 Fractional Shares.  The Company
shall not be required to issue fractional shares upon the exercise of the Option. 

5.   NONTRANSFERABILITY OF THE OPTION.

 The Option may be exercised during the lifetime of the Optionee only by the Optionee or the Optionee’s
guardian or legal representative and may not be assigned or transferred in any manner except by will or by the laws of descent and distribution. Following the death of the Optionee, the Option, to the extent provided in Section 7, may be
exercised by the Optionee’s legal representative or by any person empowered to do so under the deceased Optionee’s will or under the then applicable laws of descent and distribution. 

6.   TERMINATION OF THE OPTION. 

The Option shall terminate and may no longer be exercised after the first to occur of (a) the Option Expiration Date,
(b) the last date for exercising the Option following termination of the Optionee’s Service as described in Section 7, or (c) a Change in Control to the extent provided in Section 8. 

7.   EFFECT OF TERMINATION OF
SERVICE. 
 7.1 Option Exercisability.  Except as otherwise
provided in the Employment Agreement, the Option shall be exercisable following a termination of Optionee’s Service as follows: 

(a) Disability.     If the Optionee’s Service terminates
because of the Disability of the Optionee, the Option, to the extent unexercised and exercisable on the date on which the Optionee’s Service terminated, may be exercised by the Optionee (or the Optionee’s guardian or legal representative)
at any time prior to the expiration of twelve (12) months after the date on which the Optionee’s Service terminated, but in any event no later than the Option Expiration Date. 

(b) Death.  If the Optionee’s Service terminates because of the death of
the Optionee, the Option, to the extent unexercised and exercisable on the date on which the Optionee’s Service terminated, may be exercised by the Optionee’s legal representative or other person who acquired the right to exercise the
Option by reason of the Optionee’s death at any time prior to the expiration of twelve (12) months after the date on which the Optionee’s Service terminated, but in any event no later than the Option Expiration Date. The
Optionee’s Service shall be deemed to have terminated on account of death if the Optionee dies within three (3) months after the Optionee’s termination of Service. 

(c) [Termination After Change in Control.    If the Optionee’s Service ceases as a
result of Termination After Change in Control (as defined below), (i) the Option, to the extent unexercised and exercisable on the date on which the Optionee’s Service terminated, may be exercised by the Optionee (or the Optionee’s
guardian or legal representative) at any time prior to the expiration of six (6) months after the date on which the Optionee’s Service terminated, but in any event no later than the Option Expiration Date, and (ii) fifty percent (50%)

  
 6 

 Executive Version 

 

 
of the shares, if any, that are unvested as of the date of the Optionee’s termination of Service shall become immediately vested and exercisable.] 

(d) Other Termination of Service.  If the Optionee’s Service terminates
for any reason, except Disability, death [or Termination After Change in Control], the Option, to the extent unexercised and exercisable by the Optionee on the date on which the Optionee’s Service terminated, may be exercised by the Optionee at
any time prior to the expiration of three (3) months (or such longer period of time as determined by the Administrator, in its discretion) after the date on which the Optionee’s Service terminated, but in any event no later than the Option
Expiration Date. 
 7.2 Extension if Exercise Prevented by Law.  Notwithstanding
the foregoing, if the exercise of the Option within the applicable time periods set forth in Section 7.1 is prevented by the provisions of Section 4.6, the Option shall remain exercisable until three (3) months after the date the
Optionee is notified by the Company that the Option is exercisable, but in any event no later than the Option Expiration Date. 

7.3 Extension if Optionee Subject to Section 16(b).    Notwithstanding the foregoing, if a
sale within the applicable time periods set forth in Section 7.1 of shares acquired upon the exercise of the Option would subject the Optionee to suit under Section 16(b) of the Exchange Act, the Option shall remain exercisable until the
earliest to occur of (i) the tenth (10th) day following the date on which a sale of such shares by the Optionee would no longer be subject to such suit, (ii) the one hundred and ninetieth (190th) day after the Optionee’s
termination of Service, or (iii) the Option Expiration Date. 
 7.4 Certain Definitions. 

(a) [“Termination After Change in Control” shall mean either of the following events occurring within
twelve (12) months after a Change in Control: 
 (i)        termination by
the Company of the Optionee’s Service with the Company for any reason other than for Cause (as defined below); or 

(ii)       [the Optionee’s resignation for Good Reason (as defined below) from all
capacities in which the Optionee is then rendering Service to the Company within a reasonable period of time following the event constituting Good Reason.] 

Notwithstanding any provision herein to the contrary, Termination After Change in Control shall not include any termination of the
Optionee’s Service with the Company that (1) is for Cause (as defined below); (2) is a result of the Optionee’s death or Disability; (3) is a result of the Optionee’s voluntary termination of Service [other than for
Good Reason]; or (4) occurs prior to the effectiveness of a Change in Control.] 
 (b) “Cause”
shall have the meaning set forth in the Optionee’s employment agreement with the Company, if any, or in the absence of such employment agreement or definition, shall mean any of the following: (i) the Optionee’s theft, dishonesty, or
falsification of any Company documents or records; (ii) the Optionee’s improper use or disclosure of the Company’s confidential or proprietary information; (iii) any action by the

  
 7 

 Executive Version 

 

 
Optionee which has a detrimental effect on the Company’s reputation or business; (iv) the Optionee’s failure or inability to perform any reasonable assigned duties after written
notice from the Company of, and a reasonable opportunity to cure, such failure or inability; (v) any material breach by the Optionee of any employment agreement between the Optionee and the Company, which breach is not cured pursuant to the
terms of such agreement; or (vi) the Optionee’s conviction (including any plea of guilty or nolo contendere) of any criminal act which impairs the Optionee’s ability to perform his or her duties with the Company. 

(c) [“Good Reason” shall have the meaning set forth in the Optionee’s employment agreement with the
Company, if any, or in the absence of such employment agreement or definition, shall mean any one or more of the following: 

(i)      without the Optionee’s express written consent, the assignment to the Optionee
of any duties, or any limitation of the Optionee’s responsibilities, substantially inconsistent with the Optionee’s positions, duties, responsibilities and status with the Company immediately prior to the date of the Change in Control;

 (ii)      without the Optionee’s express written consent, the relocation of the
principal place of the Optionee’s Service to a location that is more than fifty (50) miles from the Optionee’s principal place of Service immediately prior to the date of the Change in Control, or the imposition of travel requirements
substantially more demanding of the Optionee than such travel requirements existing immediately prior to the date of the Change in Control; 

(iii)      any failure by the Company to pay, or any material reduction by the Company of,
(1) the Optionee’s base salary in effect immediately prior to the date of the Change in Control (unless reductions comparable in amount and duration are concurrently made for all other employees of the Company with responsibilities,
organizational level and title comparable to the Optionee’s), or (2) the Optionee’s bonus compensation, if any, in effect immediately prior to the date of the Change in Control (subject to applicable performance requirements with
respect to the actual amount of bonus compensation earned by the Optionee); or 

(iv)      any failure by the Company to (1) continue to provide the Optionee with the
opportunity to participate, on terms no less favorable than those in effect for the benefit of any employee or service provider group which customarily includes a person holding the employment or service provider position or a comparable position
with the Company then held by the Optionee, in any benefit or compensation plans and programs, including, but not limited to, the Company’s life, disability, health, dental, medical, savings, profit sharing, stock purchase and retirement plans,
if any, in which the Optionee was participating immediately prior to the date of the Change in Control, or their equivalent, or (2) provide the Optionee with all other fringe benefits (or their equivalent) from time to time in effect for the
benefit of any employee or service provider group which customarily includes a person holding the employment or service provider position or a comparable position with the Company then held by the Optionee.] 

  
 8 

 Executive Version 

 

 8.    CHANGE IN
CONTROL. 
 In the event of a Change in Control, the surviving, continuing,
successor, or purchasing corporation or other business entity or parent thereof, as the case may be (the “Acquiring Corporation”), may, without the consent of the Optionee, either assume the Company’s rights and obligations
under the Option or substitute for the Option a substantially equivalent option for the Acquiring Corporation’s stock. In the event the Acquiring Corporation elects not to assume the Company’s rights and obligations under the Option or
substitute for the Option in connection with the Change in Control, the Option, to the extent not previously exercised, shall terminate and cease to be outstanding effective as of the date of the Change in Control. Notwithstanding the foregoing,
shares acquired upon exercise of the Option prior to the Change in Control and any consideration received pursuant to the Change in Control with respect to such shares shall continue to be subject to all applicable provisions of this Option
Agreement except as otherwise provided herein. Furthermore, notwithstanding the foregoing, if the corporation the stock of which is subject to the Option immediately prior to an Ownership Change Event constituting a Change in Control is the
surviving or continuing corporation and immediately after such Ownership Change Event less than fifty percent (50%) of the total combined voting power of its voting stock is held by another corporation or by other corporations that are members
of an affiliated group within the meaning of Section 1504(a) of the Code without regard to the provisions of Section 1504(b) of the Code, the Option shall not terminate unless the Administrator otherwise provides in its discretion. 

9.   ADJUSTMENTS FOR CHANGES IN CAPITAL
STRUCTURE. 
 In the event of any stock dividend, stock split, reverse stock split,
recapitalization, combination, reclassification, or similar change in the capital structure of the Company, including an Equity Restructuring, appropriate adjustments shall be made in the number, Exercise Price and class of shares of stock subject
to the Option, as determined by the Administrator pursuant to Section 9 of the Plan. If a majority of the shares which are of the same class as the shares that are subject to the Option are exchanged for, converted into, or otherwise become
(whether or not pursuant to an Ownership Change Event) shares of another corporation (the “New Shares”), the Administrator may unilaterally amend the Option to provide that the Option is exercisable for New Shares. In the event of
any such amendment, the Number of Option Shares and the Exercise Price shall be adjusted in a fair and equitable manner, as determined by the Administrator, in its discretion. Notwithstanding the foregoing, any fractional share resulting from an
adjustment pursuant to this Section 9 shall be rounded down to the nearest whole number, and in no event may the Exercise Price be decreased to an amount less than the par value, if any, of the stock subject to the Option. The adjustments
determined by the Administrator shall be final, binding and conclusive. 
 10. RIGHTS AS
A STOCKHOLDER, EMPLOYEE OR CONSULTANT. 

The Optionee shall have no rights as a stockholder with respect to any shares covered by the Option until the date of the
issuance of a certificate for the shares for which the Option has been exercised (as evidenced by the appropriate entry on the books of the Company or of a duly authorized transfer agent of the Company). No adjustment shall be made for dividends,
distributions or other rights for which the record date is prior to the date such certificate is issued, 

  
 9 

 Executive Version 

 

 
except as provided in Section 9. If the Optionee is an Employee, the Optionee understands and acknowledges that, except as otherwise provided in a separate, written employment agreement
between the Company and the Optionee, the Optionee’s employment is “at will” and is for no specified term. Nothing in this Option Agreement shall confer upon the Optionee any right to continue in the service of the Company or
interfere in any way with any right of the Company to terminate the Optionee’s Service as an Employee or Consultant, as the case may be, at any time. 

11. RIGHT OF FIRST REFUSAL. 

11.1     Grant of Right of First
Refusal.    Except as provided in Section 11.7 below, in the event the Optionee, the Optionee’s legal representative, or other holder of shares acquired upon exercise of the Option proposes to
sell, exchange, transfer, pledge, or otherwise dispose of any shares acquired upon exercise of the Option (the “Transfer Shares”) to any person or entity, including, without limitation, any stockholder of the Company, the Company
shall have the right to repurchase the Transfer Shares under the terms and subject to the conditions set forth in this Section 11 (the “Right of First Refusal”). 

11.2     Notice of Proposed Transfer.    Prior to
any proposed transfer of the Transfer Shares, the Optionee shall deliver written notice (the “Transfer Notice”) to the Company describing fully the proposed transfer, including the number of Transfer Shares, the name and address of
the proposed transferee (the “Proposed Transferee”) and, if the transfer is voluntary, the proposed transfer price, and containing such information necessary to show the bona fide nature of the proposed transfer. In the event of a
bona fide gift or involuntary transfer, the proposed transfer price shall be deemed to be the Fair Market Value of the Transfer Shares, as determined by the Administrator in good faith. If the Optionee proposes to transfer any Transfer Shares to
more than one Proposed Transferee, the Optionee shall provide a separate Transfer Notice for the proposed transfer to each Proposed Transferee. The Transfer Notice shall be signed by both the Optionee and the Proposed Transferee and must constitute
a binding commitment of the Optionee and the Proposed Transferee for the transfer of the Transfer Shares to the Proposed Transferee subject only to the Right of First Refusal. 

11.3      Bona Fide Transfer.    If the
Company determines that the information provided by the Optionee in the Transfer Notice is insufficient to establish the bona fide nature of a proposed voluntary transfer, the Company shall give the Optionee written notice of the Optionee’s
failure to comply with the procedure described in this Section 11, and the Optionee shall have no right to transfer the Transfer Shares without first complying with the procedure described in this Section 11. The Optionee shall not be
permitted to transfer the Transfer Shares if the proposed transfer is not bona fide. 

11.4     Exercise of Right of First Refusal.    If
the Company determines the proposed transfer to be bona fide, the Company shall have the right to purchase all, but not less than all, of the Transfer Shares (except as the Company and the Optionee otherwise agree) at the purchase price and on the
terms set forth in the Transfer Notice by delivery to the Optionee of a notice of exercise of the Right of First Refusal within thirty (30) days after the date the Transfer Notice is delivered to the Company. The Company’s exercise or
failure to exercise the Right of First Refusal with respect to any proposed transfer described in a Transfer Notice shall not affect the Company’s right to exercise the Right of First Refusal with respect to any proposed transfer

  
 10 

 Executive Version 

 

 
described in any other Transfer Notice, whether or not such other Transfer Notice is issued by the Optionee or issued by a person other than the Optionee with respect to a proposed transfer to
the same Proposed Transferee. If the Company exercises the Right of First Refusal, the Company and the Optionee shall thereupon consummate the sale of the Transfer Shares to the Company on the terms set forth in the Transfer Notice within sixty
(60) days after the date the Transfer Notice is delivered to the Company (unless a longer period is offered by the Proposed Transferee); provided, however, that in the event the Transfer Notice provides for the payment for the Transfer Shares
other than in cash, the Company shall have the option of paying for the Transfer Shares by the present value cash equivalent of the consideration described in the Transfer Notice as reasonably determined by the Company. For purposes of the
foregoing, cancellation of any indebtedness of the Optionee to the Company shall be treated as payment to the Optionee in cash to the extent of the unpaid principal and any accrued interest canceled. 

11.5     Failure to Exercise Right of First
Refusal.   If the Company fails to exercise the Right of First Refusal in full (or to such lesser extent as the Company and the Optionee otherwise agree) within the period specified in Section 11.4 above,
the Optionee may conclude a transfer to the Proposed Transferee of the Transfer Shares on the terms and conditions described in the Transfer Notice, provided such transfer occurs not later than ninety (90) days following delivery to the Company
of the Transfer Notice. The Company shall have the right to demand further assurances from the Optionee and the Proposed Transferee (in a form satisfactory to the Company) that the transfer of the Transfer Shares was actually carried out on the
terms and conditions described in the Transfer Notice. No Transfer Shares shall be transferred on the books of the Company until the Company has received such assurances, if so demanded, and has approved the proposed transfer as bona fide. Any
proposed transfer on terms and conditions different from those described in the Transfer Notice, as well as any subsequent proposed transfer by the Optionee, shall again be subject to the Right of First Refusal and shall require compliance by the
Optionee with the procedure described in this Section 11. 
 11.6     Transferees of
Transfer Shares.  All transferees of the Transfer Shares or any interest therein, other than the Company, shall be required as a condition of such transfer to agree in writing (in a form satisfactory to the
Company) that such transferee shall receive and hold such Transfer Shares or interest therein subject to all of the terms and conditions of this Option Agreement, including this Section 11 providing for the Right of First Refusal with respect
to any subsequent transfer. Any sale or transfer of any shares acquired upon exercise of the Option shall be void unless the provisions of this Section 11 are met. 

11.7     Transfers Not Subject to Right of First
Refusal.   The Right of First Refusal shall not apply to any transfer or exchange of the shares acquired upon exercise of the Option if such transfer or exchange is in connection with an Ownership Change
Event. If the consideration received pursuant to such transfer or exchange consists of stock of the Company, such consideration shall remain subject to the Right of First Refusal unless the provisions of Section 11.9 below result in a
termination of the Right of First Refusal. 
 11.8     Assignment of Right of First
Refusal.   The Company shall have the right to assign the Right of First Refusal at any time, whether or not there has been an attempted transfer, to one or more persons as may be selected by the Company. 

  
 11 

 Executive Version 

 

 11.9     Early Termination of Right of First
Refusal.    The other provisions of this Option Agreement notwithstanding, the Right of First Refusal shall terminate and be of no further force and effect upon (a) the occurrence of a Change in
Control, unless the Acquiring Corporation assumes the Company’s rights and obligations under the Option or substitutes a substantially equivalent option for the Acquiring Corporation’s stock for the Option, or (b) the existence of a
public market for the class of shares subject to the Right of First Refusal. A “public market” shall be deemed to exist if (i) such stock is listed on a national securities exchange (as that term is used in the Exchange Act) or
(ii) such stock is traded on the over-the-counter market and prices therefor are published daily on business days in a recognized financial journal. 

12. VESTED SHARE REPURCHASE OPTION. 

12.1      Grant of Vested Share Repurchase
Option.    Except as provided in Section 12.4 below, in the event of the termination of the Optionee’s Service with the Company at any time for Cause (as defined in Section 7.4(b)), the
Company shall have the right to repurchase the shares acquired by the Optionee pursuant to the Option which are Vested Shares (the “Repurchase Shares”) under the terms and subject to the conditions set forth in this Section 12
(the “Vested Share Repurchase Option”). 
 12.2     Exercise of Vested Share
Repurchase Option.    The Company may exercise the Vested Share Repurchase Option by written notice to the Optionee or other holder of the Repurchase Shares, as the case may be, during the Repurchase Period. The
“Repurchase Period” shall be the period commencing at the time set forth in Section 12.1 above and ending on the later of (a) the date ninety (90) days after the commencement of the Repurchase Period or (b) the
date ninety (90) days after the Option is last exercised. If the Company fails to give notice during the Repurchase Period, the Vested Share Repurchase Option shall terminate (unless the Company and the Optionee have extended the time for the
exercise of the Vested Share Repurchase Option) unless and until there is a subsequent Repurchase Event. Notwithstanding a termination of the Vested Share Repurchase Option, the remaining provisions of this Option Agreement shall remain in full
force and effect, including, without limitation, the Right of First Refusal set forth in Section 11. The Vested Share Repurchase Option must be exercised, if at all, for all of the Repurchase Shares, except as the Company and the Optionee
otherwise agree. 
 12.3     Payment for Repurchase Shares.  The repurchase
price per share being repurchased by the Company pursuant to the Vested Share Repurchase Option shall be an amount equal to the Fair Market Value of the shares determined as of the date of the Repurchase Event by the Administrator in good faith.
Payment by the Company to the Optionee shall be made in cash on or before the last day of the Repurchase Period. 

12.4     Transfers Not Subject to Vested Share Repurchase
Option.    The Vested Share Repurchase Option shall not apply to any transfer or exchange of shares acquired upon exercise of the Option if such transfer or exchange is in connection with an Ownership Change Event. If the
consideration received pursuant to such transfer or exchange consists of stock of the Company, such consideration will remain subject to the Vested Share Repurchase 

  
 12 

 Executive Version 

 

 
Option unless the provisions of Section 12.6 below result in a termination of the Vested Share Repurchase Option. 

12.5     Assignment of Vested Share Repurchase Option.  The Company shall have
the right to assign the Vested Share Repurchase Option at any time, whether or not such option is then exercisable, to one or more persons as may be selected by the Company. 

12.6     Early Termination of Vested Share Repurchase Option.    The
other provisions of this Option Agreement notwithstanding, the Vested Share Repurchase Option shall terminate and be of no further force and effect upon (a) the occurrence of a Change in Control, unless the Acquiring Corporation assumes the
Company’s rights and obligations under the Option or substitutes a substantially equivalent option for the Acquiring Corporation’s stock for the Option, or (b) the existence of a public market, as defined in Section 11.9, for the
class of shares subject to the Vested Share Repurchase Option. 
 13.
ESCROW. 

13.1     Establishment of Escrow.  To ensure that shares
subject to the Right of First Refusal or the Vested Share Repurchase Option will be available for repurchase, the Company may require the Optionee to deposit the certificate evidencing the shares which the Optionee purchases upon exercise of the
Option with an agent designated by the Company under the terms and conditions of an escrow agreement approved by the Company. If the Company does not require such deposit as a condition of exercise of the Option, the Company reserves the right at
any time to require the Optionee to so deposit the certificate in escrow. Upon the occurrence of an Ownership Change Event or a change, as described in Section 9, in the character or amount of any of the outstanding stock of the corporation the
stock of which is subject to the provisions of this Option Agreement, any and all new, substituted or additional securities or other property to which the Optionee is entitled by reason of the Optionee’s ownership of shares of Stock acquired
upon exercise of the Option that remain, following such Ownership Change Event or change described in Section 9, subject to the Right of First Refusal or Vested Share Repurchase Option, shall be immediately subject to the escrow to the same
extent as such shares of Stock immediately before such event. The Company shall bear the expenses of the escrow. 

13.2     Delivery of Shares to Optionee.    As
soon as practicable after the expiration of the Right of First Refusal and the Vested Share Repurchase Option, but not more frequently than twice each calendar year, the escrow agent shall deliver to the Optionee the shares and any other property no
longer subject to such restrictions. 
 13.3     Notices and
Payments.  In the event the shares and any other property held in escrow are subject to the Company’s exercise of the Right of First Refusal or the Vested Share Repurchase Option, the notices required to be
given to the Optionee shall be given to the escrow agent, and any payment required to be given to the Optionee shall be given to the escrow agent. Within thirty (30) days after payment by the Company, the escrow agent shall deliver the shares
and any other property which the Company has purchased to the Company and shall deliver the payment received from the Company to the Optionee. 

  
 13 

 Executive Version 

 

 14. STOCK DISTRIBUTIONS SUBJECT
TO OPTION AGREEMENT. 
 If, from time to time, there
is any stock dividend, stock split or other change, including an Equity Restructuring, as described in Section 9, in the character or amount of any of the outstanding stock of the corporation the stock of which is subject to the provisions of
this Option Agreement, then in such event any and all new, substituted or additional securities to which the Optionee is entitled by reason of the Optionee’s ownership of the shares acquired upon exercise of the Option shall be immediately
subject to the Right of First Refusal and Vested Share Repurchase Option with the same force and effect as the shares subject to the Right of First Refusal and Vested Share Repurchase Option immediately before such event. 

15. NOTICE OF SALES UPON DISQUALIFYING
DISPOSITION. 
 The Optionee shall dispose of the shares acquired pursuant to the
Option only in accordance with the provisions of this Option Agreement. In addition, if the Notice designates this Option as an Incentive Stock Option, the Optionee shall (a) promptly notify the President of the Company if the Optionee
disposes of any of the shares acquired pursuant to the Option within one (1) year after the date the Optionee exercises all or part of the Option or within two (2) years after the Date of Option Grant and (b) provide the Company with
a description of the circumstances of such disposition. Until such time as the Optionee disposes of such shares in a manner consistent with the provisions of this Option Agreement, unless otherwise expressly authorized by the Company, the Optionee
shall hold all shares acquired pursuant to the Option in the Optionee’s name (and not in the name of any nominee) for the one-year period immediately after the exercise of the Option and the two-year period immediately after Date of Option
Grant. At any time during the one-year or two-year periods set forth above, the Company may place a legend on any certificate representing shares acquired pursuant to the Option requesting the transfer agent for the Company’s stock to notify
the Company of any such transfers. The obligation of the Optionee to notify the Company of any such transfer shall continue notwithstanding that a legend has been placed on the certificate pursuant to the preceding sentence. 

16. LEGENDS. 

The Company may at any time place legends referencing the Right of First Refusal or the Vested Share Repurchase Option, and
any applicable federal, state or foreign securities law restrictions on all certificates representing shares of stock subject to the provisions of this Option Agreement. The Optionee shall, at the request of the Company, promptly present to the
Company any and all certificates representing shares acquired pursuant to the Option in the possession of the Optionee in order to carry out the provisions of this Section. Unless otherwise specified by the Company, legends placed on such
certificates may include, but shall not be limited to, the following: 
 16.1     “THE
SECURITIES EVIDENCED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT BE SOLD, TRANSFERRED, ASSIGNED OR HYPOTHECATED UNLESS THERE IS AN EFFECTIVE REGISTRATION STATEMENT UNDER SUCH ACT COVERING
SUCH SECURITIES, THE SALE IS MADE IN ACCORDANCE WITH RULE 

  
 14 

 Executive Version 

 

 
144 OR RULE 701 UNDER THE ACT, OR THE COMPANY RECEIVES AN OPINION OF COUNSEL REASONABLY SATISFACTORY TO THE COMPANY, STATING THAT SUCH SALE, TRANSFER, ASSIGNMENT OR HYPOTHECATION IS EXEMPT
FROM THE REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS OF SUCH ACT.” 

16.2     “THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO A RIGHT OF FIRST REFUSAL
OPTION AND VESTED SHARE REPURCHASE OPTION IN FAVOR OF THE CORPORATION OR ITS ASSIGNEE SET FORTH IN AN AGREEMENT BETWEEN THE CORPORATION AND THE REGISTERED HOLDER, OR SUCH HOLDER’S PREDECESSOR IN INTEREST, A COPY OF WHICH IS ON FILE AT THE
PRINCIPAL OFFICE OF THIS CORPORATION.” 
 16.3     “THE SHARES EVIDENCED BY THIS
CERTIFICATE WERE ISSUED BY THE CORPORATION TO THE REGISTERED HOLDER UPON EXERCISE OF AN INCENTIVE STOCK OPTION AS DEFINED IN SECTION 422 OF THE INTERNAL REVENUE CODE OF 1986, AS AMENDED (“ISO”). IN ORDER TO OBTAIN THE
PREFERENTIAL TAX TREATMENT AFFORDED TO ISOs, THE SHARES SHOULD NOT BE TRANSFERRED PRIOR TO [INSERT DISQUALIFYING DISPOSITION DATE HERE]. SHOULD THE REGISTERED HOLDER ELECT TO TRANSFER ANY OF THE SHARES PRIOR TO THIS DATE AND FOREGO ISO TAX
TREATMENT, THE TRANSFER AGENT FOR THE SHARES SHALL NOTIFY THE CORPORATION IMMEDIATELY. THE REGISTERED HOLDER SHALL HOLD ALL SHARES PURCHASED UNDER THE INCENTIVE STOCK OPTION IN THE REGISTERED HOLDER’S NAME (AND NOT IN THE NAME OF ANY NOMINEE)
PRIOR TO THIS DATE OR UNTIL TRANSFERRED AS DESCRIBED ABOVE.” 
 17. LOCK-UP
AGREEMENT. 
 The Optionee hereby agrees that in the event of any underwritten
public offering of stock, including an initial public offering of stock, made by the Company pursuant to an effective registration statement filed under the Securities Act, the Optionee shall not offer, sell, contract to sell, pledge, hypothecate,
grant any option to purchase or make any short sale of, or otherwise dispose of any shares of stock of the Company or any rights to acquire stock of the Company for such period of time from and after the effective date of such registration statement
as may be established by the underwriter for such public offering; provided, however, that such period of time shall not exceed one hundred eighty (180) days from the effective date of the registration statement to be filed in connection with
such public offering. The foregoing limitation shall not apply to shares registered in the public offering under the Securities Act. 

18. RESTRICTIONS ON TRANSFER OF SHARES.

 No shares acquired upon exercise of the Option may be sold, exchanged, transferred (including, without limitation,
any transfer to a nominee or agent of the Optionee), assigned, pledged, hypothecated or otherwise disposed of, including by operation of law, in any manner which violates any of the provisions of this Option Agreement and any such attempted
disposition shall be void. The Company shall not be required (a) to transfer on its books any shares which will have been transferred in violation of any of the provisions set forth in this 

  
 15 

 Executive Version 

 

 
Option Agreement or (b) to treat as owner of such shares or to accord the right to vote as such owner or to pay dividends to any transferee to whom such shares will have been so transferred.

 19. MISCELLANEOUS PROVISIONS. 

19.1     Binding Effect.  Subject to the restrictions on transfer set forth
herein, this Option Agreement shall inure to the benefit of and be binding upon the parties hereto and their respective heirs, executors, administrators, successors and assigns. 

19.2     Termination or Amendment.    The Administrator may terminate
or amend the Plan or the Option at any time; provided, however, that except as provided in Section 8 in connection with a Change in Control, no such termination or amendment may adversely affect the Option or any unexercised portion hereof
without the consent of the Optionee unless such termination or amendment is necessary to comply with any applicable law or government regulation or is required to enable the Option, if designated an Incentive Stock Option in the Notice, to qualify
as an Incentive Stock Option. No amendment or addition to this Option Agreement shall be effective unless in writing. 

19.3     Notices.  Any notice required or permitted hereunder shall be given in
writing and shall be deemed effectively given (except to the extent that this Option Agreement provides for effectiveness only upon actual receipt of such notice) upon personal delivery or upon deposit in the United States Post Office, by registered
or certified mail, with postage and fees prepaid, addressed to the other party at the address shown below that party’s signature or at such other address as such party may designate in writing from time to time to the other party. 

19.4     Integrated Agreement.  The Notice, this Option Agreement and the Plan
[and the Employment Agreement] constitute the entire understanding and agreement of the Optionee and the Company with respect to the subject matter contained herein or therein and supersedes any prior agreements, understandings, restrictions,
representations, or warranties among the Optionee and the Company with respect to such subject matter other than those as set forth or provided for herein or therein. To the extent contemplated herein or therein, the provisions of the Notice and the
Option Agreement shall survive any exercise of the Option and shall remain in full force and effect. 

19.5     Applicable Law.  This Option Agreement shall be governed by the laws of
the State of California as such laws are applied to agreements between California residents entered into and to be performed entirely within the State of California. 

19.6     Counterparts.   The Notice may be executed in counterparts, each of
which shall be deemed an original, but all of which together shall constitute one and the same instrument. 

  
 16 

					
	        Incentive Stock Option	  	Optionee:	  	  

	        Nonstatutory Stock Option	  		  	

					
		  	Date:	  	  

 STOCK OPTION EXERCISE NOTICE 

(STANDARD VESTING) 
  

			
	Ambrx, Inc.	 	
	Attention: Chief Business Officer	 	
	  
	 	
	  
	 	

 Ladies and Gentlemen: 

1.        Option.  I was granted an option (the
“Option”) to purchase shares of the common stock (the “Shares”) of Ambrx, Inc. (the “Company”) pursuant to the Company’s 2013 Equity Incentive Plan, as amended from time to time (the
“Plan”), my Notice of Grant of Stock Option (the “Notice”) and my Stock Option Agreement (the “Option Agreement”) as follows: 

 

					
	Grant Number:	 	  

	  
 Date of Option Grant:
	 	  

	  
 Number of Option Shares:
	 	  

	  
 Exercise Price per Share:
	 	$	 	  

 2.        Exercise of Option.  I
hereby elect to exercise the Option to purchase the following number of Shares: 
  

					
	Total Shares Purchased:	 	  

	  
 Total Exercise Price (Total Shares X Price per Share)
	 	$	 	  

 3.        Payments.  I enclose
payment in full of the total exercise price for the Shares in the following form(s), as authorized by my Option Agreement: 
  

							
	 ̈	 	Cash:	 	$	 	  

	 ̈	 	  
 Check:
	 	$	 	  

	 ̈	 	  
 Tender of Company Stock:
	 	Contact Plan Administrator

  
 1 

 4.        Tax
Withholding.  I authorize payroll withholding and otherwise will make adequate provision for the federal, state, local and foreign tax withholding obligations of the Company, if any, in connection with the Option. If I am
exercising a Nonstatutory Stock Option, I enclose payment in full of my withholding taxes, if any, as follows: 
 (Contact Plan
Administrator for amount of tax due.) 
  

							
	 ̈	 	Cash:	 	$	 	  

	 ̈	 	  
 Check:
	 	$	 	  

 5.        Optionee Information. 

 

			
	 My address is:	 	  

		
		 	  

 
			
		
	 My Social Security Number is:	 	  

 6.        Notice of Disqualifying
Disposition. If the Option is an Incentive Stock Option, I agree that I will promptly notify the President of the Company if I transfer any of the Shares within one (1) year from the date I exercise all or part of the Option or within
two (2) years of the Date of Option Grant. 
 7.        Binding
Effect. I agree that the Shares are being acquired in accordance with and subject to the terms, provisions and conditions of the Option Agreement, including the Right of First Refusal and Vested Share Repurchase Option set forth therein, to
all of which I hereby expressly assent. This Agreement shall inure to the benefit of and be binding upon my heirs, executors, administrators, successors and assigns. If required by the Company, I agree to deposit the certificate(s) evidencing the
Shares, along with a blank stock assignment separate from certificate executed by me, with an escrow agent designated by the Company, to be held pursuant to the Company’s standard Joint Escrow Instructions. 

8.        Transfer.  I understand and acknowledge that the Shares
have not been registered under the Securities Act of 1933, as amended (the “Securities Act”), and that consequently the Shares must be held indefinitely unless they are subsequently registered under the Securities Act, an exemption
from such registration is available, or they are sold in accordance with Rule 144 or Rule 701 under the Securities Act. I further understand and acknowledge that the Company is under no obligation to register the Shares. I understand that
the certificate or certificates evidencing the Shares will be imprinted with legends which prohibit the transfer of the Shares unless they are registered or such registration is not required in the opinion of legal counsel satisfactory to the
Company. 
 I am aware that Rule 144 under the Securities Act, which permits limited public resale of securities
acquired in a nonpublic offering, is not currently available with respect to the Shares and, in any event, is available only if certain conditions are satisfied. I understand that any sale of the Shares that might be made in reliance upon
Rule 144 may only be made in limited amounts in accordance with the terms and conditions of such rule and that a copy of Rule 144 will be delivered to me upon request. 

  
 2 

 I understand that I am purchasing the Shares pursuant to the terms of the Plan,
the Notice and my Option Agreement, copies of which I have received and carefully read and understand. 
  

			
	Very truly yours,	 	
		
	  
	 	
	(Signature)	 	

  

			
	Receipt of the above is hereby acknowledged.
	
	AMBRX, INC.
		
	By:	 	  

			
		
	Title:	 	  

			
		
	Dated:	 	  

  
 3EX-10.5

 Exhibit 10.5 

EXECUTIVE EMPLOYMENT AGREEMENT 

This Executive Employment Agreement (“Agreement”) is made effective as Jan 6, 2013 (“Effective
Date”), by and between Ambrx, Inc., a Delaware corporation (the “Company”), and Lawson Macartney (“Executive”). 

The parties agree as follows; 

1.   Employment.  The Company hereby employs Executive commenting effective as of February 1, 2013 (the
“Employment Commencement Date”), and Executive hereby accepts such employment, upon the terms and conditions set forth herein. 

2.   Duties. 

2.1        Position.  Executive shall be employed as the Company’s
President & Chief Executive Officer, reporting to the Company’s Board of Directors (the “Board”), and shall have the duties and responsibilities customarily associated with such position and as may be reasonably
assigned from time to time by the Board, Executive shall perform faithfully and diligently all functions associated with his position and all duties assigned to him.-So long as Executive is serving as the President & Chief Executive Officer
of the Company, he will be nominated by the Board to, and if elected by the stockholders of the Company, serve as a member of, the Board. 

2.2        Best Efforts/Full-Time.  Executive shall perform the duties and
responsibilities assigned to him by the Board on behalf of the Company to the best of his abilities and with reasonable diligence, and shall abide by all lawful policies and decisions made by the Company, as well as all applicable federal, state and
local laws, regulations or ordinances. Executive shall act in the best interest of the Company at all times, Executive shall devote Executive’s full business time and efforts to the performance of Executive’s assigned duties for the
Company. 
 2.3        Policies and Procedures.  Executive agrees to comply with
the Company’s regular policies and procedures as such policies and procedures may be modified from time to time, including, but not limited to, maintaining the confidentiality of the Company’s confidential information, assigning to the
Company inventions made by Executive during the term of his employment and not pursuing competitive activities during the term of employment. 

3.   At-Will Employment Relationship.  Executive’s employment with the Company is at-will and not for any
specified period and may be terminated at any time, with or without Cause or advance notice, by either Executive or the Company. In addition, the Company reserves the right to modify Executive’s position or duties to meet business needs and to
use discretion in deciding on appropriate discipline. No representative of the Company, other than an authorized representative of the Board, has the authority to alter the at-will employment relationship. Any change to the at-will employment
relationship must be by specific, written agreement signed by Executive and an authorized representative of the Company. Nothing in this Agreement is intended to or should be construed to contradict, modify or alter this at-will relationship. If
Executive’s employment with the Company terminates for any reason, Executive shall not be entitled to any payments, benefits, damages, awards or compensation other than as provided in this Agreement. 

4.   Compensation. 

4.1        Base Salary.  As compensation for Executive’s performance of his
duties hereunder, the Company shall pay to Executive an initial bi-weekly base salary paid of $ 17,307.70 per 

  
 1 

 
pay period (an annual rate of $450,000 per year) (the “Base Salary”). The Base Salary is payable in arrears in accordance with the normal payroll practices of the Company, less
required deductions for state and federal withholding tax, social security and all other employment taxes and authorized payroll deductions. In the event Executive’s employment under this Agreement is terminated by either party, for any reason,
Executive shall earn the Base Salary prorated to the date of termination of employment. 

4.2        Discretionary Bonus.  Executive shall participate in such bonus plan or
plans as in effect from time-to-time and applicable to the senior management of the Company. Executive’s target bonus award under such bonus plan shall be forty percent (40%) of Executive’s Base Salary (the Target Bonus”).
Executive’s bonus (if any) shall be determined by the Board or its designee, in its sole and absolute discretion, in accordance with the terms and conditions of the Company’s bonus plan. The Executive’s 2013 annual bonus will be based
on performance criteria to be approved by the Board of Directors no later than March 31, 2013. 

4.3        Commuting Allowance. 

(a)        For each of the first three twelve (12) month periods following the Employment
Commencement Date, the Company shall provide to Executive $100,000 in cash (“Commuting Allowance Amounts”) for the expenses incurred by Executive to maintain a separate apartment in the County of San Diego, California and to assist
with commuting expenses to and from the Company’s corporate offices in San Diego, California. The Commuting Allowance Amounts shall be paid in quarterly installments, commencing on the Employment Commencement Date and every three
(3) months thereafter on the date of the applicable calendar month corresponding with the Employment Commencement Date, provided that the Executive remains an employee of the Company through each applicable Commuting Allowance installment
payment date. For ease of administration, each installment of the Commuting Allowance Amount may be paid through the Company’s payroll practices during the applicable calendar month in which such payment is due. The Commuting Allowance Amounts
shall be treated as taxable compensation at the time of payment and shall be subject to any tax withholding and payroll deductions required by applicable law. Following the third anniversary of the Employment Commencement Date, the Company and
Executive may discuss whether to continue payment of Commuting Allowance Amounts for some additional period of time. 

(b)  Except as provided below, the Commuting Allowance Amounts shall not be earned by Executive unless and until Executive has
remained continuously employed by the Company through the first anniversary of the Employment Commencement Date, If Executive’s employment with the Company is terminated by the Company for Cause or by the Executive for any reason (except as
provided below), in either case, before the first anniversary of the Employment Commencement Date, Executive shall repay to the Company the total Commuting Allowance Amounts provided by the Company pursuant to Section 4.3(a) as of the date of
the termination of Executive’ s employment. The Company shall have the right to offset such amounts against any compensation or benefits otherwise payable to Executive on the date of termination of employment. If Executive’s employment is
terminated (i) by the Company without Cause or as a result of Executive’s death or Disability, or (ii) by Executive due to, without Executive’s consent, (x) a material diminution in Executive’s authority or responsibilities
(including a material adverse change in Executive’s reporting line) or (y) a material change in the geographic location at which Executive must perform his duties other than reasonably required travel on the Company’s business (for
purposes of this provision, a “material change” shall not include a relocation of the Company’s headquarters to a location within fifty (50) miles of Philadelphia, Pennsylvania), in each case, before the first anniversary of the
Employment Commencement Date, Executive shall earn the Commuting Allowance Amounts provided by the Company pursuant to Section 4.3(a). 

  
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 4.4        Stock Awards. 

(a)            (i)          
Subject to the approval of the Board, the Company shall grant to Executive a stock option to purchase the number of shares of the Company’s common stock that represents four percent (4%) of the Company’s common stock on a fully-diluted
basis as of the Employment Commencement Date (the “Service-Based Vesting Option”), which shall vest as follows: 

(A)        25% of the shares subject to the Service-Based Vesting Option shall vest
on the first year anniversary of the Employment Commencement Date, subject to Executive’s continued employment or service with the Company through such vesting date. 

(B)        75% of the shares subject to the Service-Based Vesting Option shall vest
in thirty-six (36) equal monthly installments on the last day of each calendar month during a three year period commencing on the first year anniversary of the Employment Commencement Date, subject to Executive’s continued employment or
service with the Company through the applicable vesting date. 
 Such vesting terms and conditions shall be set forth in the Stock Option Agreement pursuant
to which the Service-Based Vesting Option is granted. Subject to the approval by the Board, the Service-Based Vesting Options shall be granted as soon as practicable following the Employment Commencement Date. 

(ii)        Performance-Based Vesting Option. Subject to the approval of the Board, the
Company shall grant to Executive one or more performance-based vesting options, to be evidenced by the Stock Option Agreement most recently approved for use by the Board and pursuant to the terms and conditions set forth herein. In the event that
Executive is granted an IPO Option pursuant to Section 4.4(a)(iii) hereof, Executive shall not be granted any performance-based vesting options pursuant to this Section 4.4(a)(ii). 

(A)        Subject to Executive’s continued employment with the Company through
the date of grant, upon return to the Company’s investors as of the Employment Commencement Date of $210 million or more (which amount represents 200% of such investors’ invested capital as of the Employment Commencement Date) through one
or more mergers, acquisitions, asset sales, joint ventures, dividends or otherwise (each, a “Return Event”), as determined by the Board in its sole discretion and subject to approval by the Board, Executive shall be granted a stock
option (the “Initial Performance-Based Vesting Option”) to purchase a number of shares of the Company’s common stock representing ownership of three quarters of one percent (0.75%) of the total equity of the Company on a fully
diluted basis as of the Employment Commencement Date. The Initial Performance-Based Vesting Option shall be fully vested at the time of grant; and 

(B)        Subject to Executive’s continued employment with the Company through
the date of grant, upon return to the Company’s investors as of the Employment Commencement Date of $420 million or more (which amount represents 400% of such investors’ invested capital as of the Employment Commencement Date) through one
or more Return Events, as determined by the Board in its sole discretion and subject to approval by the Board, Executive shall be granted a stock option (the “Second Performance-Based Vesting Option,” and together with the Initial
Performance-Based Vesting Option, the “Performance-Based Vesting Options”) to purchase a number of shares of the Company’s common stock representing ownership of an additional three quarters of one percent (0.75%) of the total
equity of the Company on a fully diluted basis as of the Employment Commencement Date, The Second Performance-Based Vesting Option shall be fully vested at the time of grant. 

  
 3 

 (iii)        Initial Public Offering Option.
Subject to Executive’s continued employment through the date of grant, in the event of the initial public offering of the Company’s common stock to the general public pursuant to a registration statement filed with, and declared effective
by, the Securities and Exchange Commission under the Securities Act of 1933, as amended (an “IPO”), Executive shall be granted a stock option (the “IPO Option”) as of the date that the trading price of the shares of
the Company’s common stock is established for purposes of the IPO (the “IPO Pricing Date”) to purchase a number of shares of the Company’s common stock equal to one and one half percent (1.5%) of the total equity of
the Company on a fully diluted basis as of the Employment Commencement Date. The IPO Option shall vest as follows (X) 25% of the shares subject to the IPO Option shall vest on the first year anniversary of the IPO Pricing Date, subject to
Executive’s continued employment or service with the Company through such vesting date, and (Y) 75% of the shares subject to the IPO Option shall vest in twelve (12) equal monthly installments on the last day of each calendar month
during the twelve-month period commencing on the first year anniversary of the IPO Pricing Date, subject to Executive’s continued employment or service with the Company through each applicable vesting date. In the event that Executive is
granted any Performance-Based Vesting Option pursuant to Section 4.4(a)(ii) hereof, Executive shall not be granted an IPO Option pursuant to this Section 4,4(a)(iii). 

(iv)         The Service-Based Vesting Option, the Performance-Based Vesting Options and the IPO
Option (collectively, the “Options”) shall be granted pursuant to the Ambrx, Inc. 2003 Stock Option Plan (or any Board-approved successor plan) (the “Incentive Plan”) and shall have an exercise price per share equal
to the then-current fair market value per share of the Company s common stock (as determined pursuant to the Incentive Plan) on the date of the grant of the Options. The Options shall be incentive stock options to the extent permitted under
Section 422 of the Internal Revenue Code of 1986, as amended (the “Code”). The Options shall have a ten (10) year term and shall be subject to the terms and conditions of the Incentive Plan, as in effect from time to time,
and the Stock Option Agreements pursuant to which such Options are granted. The total equity of the Company on a fully diluted basis as of the Employment Commencement Date is set forth on Schedule 1 hereto. 

(b)        (i)           If Executive’s
employment with the Company is terminated (x) by the Company without Cause or (y) by Executive due to, without Executive’s consent, (1) a material diminution in Executive’s authority or responsibilities (including a material
adverse change in Executive s reporting line) or (2) a material change in the geographic location at which Executive must perform his duties other than reasonably required travel on the Company’s business (for purposes of this provision, a
“material change” shall not include a relocation of the Company’s headquarters to a location within fifty (50) miles of Philadelphia, Pennsylvania), in each case, within three (3) months prior to or twelve (12) months
following a Change in Control, the vesting and exercisability of one hundred percent (100%) of Executive’s outstanding unvested Stock Awards, other than the Performance-Based Vesting Options and IPO Option, shall be automatically
accelerated on the later of (A) the date of termination of employment or (B) the date of the Change in Control, In addition, Executive’s Stock Awards, other than the Performance-Based Vesting Options and IPO Option, may be exercised
by Executive (or Executive’s guardian or legal representative) until the latest of (X) six (6) months after the date of termination of employment, (Y) with respect to any portion of the Stock Awards that become exercisable on the
date of a Change in Control pursuant to this Section 4.4(b)(i), six (6) months after the date of the Change in Control, or (Z) such longer period as may be specified in the applicable Stock Award agreement; provided,
however, that in no event shall any Stock Award remain exercisable beyond the original expiration date of such Stock Award. 

(ii)         If Executive’s employment with the Company is terminated due to death or
Disability, in either ease, the vesting and exercisability of twenty-five percent (25%) of Executive s outstanding unvested Stock Awards, other than the Performance-Based Vesting Options and IPO Option, shall be automatically accelerated on the
date of termination of employment. 

  
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 (iii)        The vesting pursuant to clauses
(i) and (ii) of this Section 4.4(b) shall be cumulative. The foregoing provisions are hereby deemed to be a part of each Stock Award and to supersede any less favorable provision in any agreement or plan regarding such Stock Award.

 (c)        “Stock Awards” means all stock options, restricted stock and such
other awards granted pursuant to the Company’s stock option and equity incentive award plans or agreements and any shares of stock issued upon exercise thereof, including without limitation, the Options. 

4.5      Performance and Salary Review.  The Board or its designee shall review
Executive’s performance annually. Adjustments to Base Salary, Target Bonus, or other compensation, if any, and any additional giants of Stock Awards shall be made by the Board or its designee in its sole and absolute discretion. 

5.   Customary Fringe Benefits. 

(a)  Executive shall be eligible for all customary and usual fringe benefits generally available to senior executives at a same or
similar level of responsibility at the Company, including but not limited to group health insurance (subject to Section 5(a) hereof), subject to the terms and conditions of the Company’s benefit plan documents. Executive shall be entitled
to paid time-off in accordance with the Company policies. The Company reserves the right to change or eliminate the fringe benefits on a prospective basis, at any time, effective upon notice to Executive. 

(b)  Executive hereby acknowledges that the Company has made available to him group health insurance under a plan maintained by the
Company or its affiliate, and Executive hereby elects to decline and waive the right to receive or enroll in such health insurance coverage in exchange for the right to receive additional compensation at a rate of $25,000 per year, payable bi-weekly
in accordance with the Company’s regular payroll practices (the “Supplemental Payment”), The Supplemental Payment shall be treated as taxable compensation at the time of payment and shall be subject to any tax withholding and
payroll deductions required by applicable law. In the event that Executive’s waiver under this Section 5(b) is found to be ineffective under or violate the Patient Protection and Affordable Care Act or any official guidance promulgated
thereunder, Executive hereby agrees to that the Supplemental Payment will terminated, and Executive will repay to the Company any Supplemental Payments received during any period for which Executive’s waiver under this Section 5(b) is
found to be ineffective under or violate the Patient Protection and Affordable Care Act or any official guidance promulgated thereunder. 

6.   Business Expenses.  Executive shall be reimbursed for all reasonable, out-of-pocket business expenses
reasonably incurred in the performance of Executive’s duties or professional activities on behalf of the Company, including but not limited to travel expenses in accordance with the Company’s travel expense policy. To obtain reimbursement,
expenses must be submitted promptly with appropriate supporting documentation in accordance with the Company’s policies. 

7.   Severance.  Executive shall be entitled to receive benefits upon Executive’s Separation from Service
by reason of termination of Executive’s employment with the Company only as set forth in this Section 7. 

(a)  Certain Qualifying Terminations of Employment.  If Executive’s Separation from Service occurs by reason
of the termination of Executive’s employment (i) by the Company without Cause or (ii) by Executive due to, without Executive’s consent, (x) a material diminution in Executive’s authority or responsibilities (including a
material adverse change in Executive’s reporting line) or (y) a material change in the geographic location at which Executive must perform his duties other than 

  
 5 

 
reasonably required travel on the Company’s business (for purposes of this provision, a “material change” shall not include a relocation of the Company’s headquarters to a
location within fifty (50) miles of Philadelphia, Pennsylvania), in each case, Executive shall be entitled to receive, in lieu of any severance benefits to which Executive may otherwise be entitled under any severance plan or program of
Company, the benefits provided below: 
 (i)         The Company shall pay to
Executive his fully earned but unpaid Base Salary, when due, through the date of Separation from Service at the rate then in effect, plus all other amounts to which Executive is entitled under any compensation plan or practice of the Company at the
time of Separation from Service; 
 (ii)        Subject to Executive’s
continued compliance with Sections 8, 9 and 10, Executive shall be entitled to receive a total severance benefit in cash in an amount equal to: (A) twelve (12), multiplied by (B) Executive’s monthly Base Salary as in effect immediately
prior to the date of Separation from Service. Such severance benefit shall be payable in twelve (12) equal monthly installments on the first day of each calendar month, commencing on the first day of the calendar month on or next following the
sixtieth (60th) day after the date of Executive’s Separation from Service; and 

(iii)       In the event Executive accepts employment with an employer other than the Company during the
period commencing on the ninetieth (90th) day following his Separation from Service and throughout the remainder of the severance payment period described in Section 7(a)(ii) (which
acceptance may be evidenced upon the earlier of executing a written employment agreement or commencing such employment), the Company’s obligation to pay severance benefits under Section 7(a)(ii) shall immediately cease upon such acceptance
of other employment, and Executive shall be obligated to inform the Company of any such acceptance within five (5) business days of such acceptance; provided, however, that this Section 7(a)(iii) shall not apply in the event
Executive’s employment is terminated for any reason set forth in the first paragraph of Section 7(a) hereof within three (3) months prior to or twelve (12) months following a Change in Control. 

(b)        Other Terminations.  If Executive’s employment is terminated at any
time by the Company or Executive for any reason other than as set forth in Section 7(a) herein, or as a result of Executive’s death or Disability, the Company shall not have any other or further obligations to Executive under this
Agreement (including any financial obligations) except that Executive shall be entitled to receive (i) Executive’s fully earned but unpaid Base Salary, through the date of termination at the rate then in effect, and (ii) all other
amounts or benefits to which Executive is entitled under any compensation, retirement or benefit plan or practice of the Company at the time of termination in accordance with the terms of such plans or practices, including, without limitation, any
continuation of benefits required by COBRA or applicable law. In addition, except as provided in Section 4.4(b), all vesting of Executive’s unvested Stock Awards previously granted to him by the Company shall cease and none of such
unvested Stock Awards shall be exercisable following the date of such termination. The foregoing shall be in addition to, and not in lieu of, any and all other rights and remedies which may be available to the Company under the circumstances,
whether at law or in equity. 
 (c)        Delay of Payments.  If at the time of
Executive’s Separation from Service, Executive is a “specified employee” as defined in Section 409A of the Code, as determined by the Company in accordance with Section 409A of the Code, and the deferral of the commencement
of any payments or benefits otherwise payable hereunder as a result of such Separation from Service is necessary in order to prevent any accelerated or additional tax under Section 409A of the Code, then the Company shall defer the commencement
of the payment of any such payments or benefits hereunder (without any reduction in such payments or benefits ultimately paid or provided to Executive) until the date that is at least six (6) months following Executive’s Separation from
Service (or the earliest date as is permitted under Section 409A of the Code). 

  
 6 

 (d)        Release.  As a condition to
Executive’s receipt of any benefits pursuant to Section 7(a) and/or Section 4.4(b) above, Executive shall execute and deliver to the Company no later than the twenty-first
(21st) day after the Release is presented to him (the “Review Period”), and not revoke, a general release of all claims in favor of the Company (the
“Release”) in the form attached hereto as Exhibit A. Such Release shall specifically relate to all of Executive’s rights and claims in existence at the time of such execution, including any claims related to
Executive’s employment by the Company and his termination of employment, and shall exclude any continuing obligations the Company may have to Executive following the date of termination under this Agreement or any other agreement providing for
obligations to survive Executive’s termination of employment. In the event Executive does not execute and deliver the Release to the Company within the Review Period, or Executive revokes the Release, Executive shall not be entitled to the
aforesaid payments and benefits. 
 (e)        Exclusive Remedy.  Except as
otherwise expressly required by law (e.g., COBRA) or as specifically provided herein, all of Executive’s rights to salary, severance, benefits, bonuses and other amounts hereunder (if any) accruing after the termination of Executive s
employment shall cease upon such termination. In the event of a termination of Executive’s employment with the Company, Executive’s sole remedy shall be to receive the payments and benefits described in this Section 7. In addition,
Executive acknowledges and agrees that he is not entitled to any reimbursement by the Company for any taxes payable by Executive as a result of the payments and benefits received by Executive pursuant to this Section 7, including, without
limitation, any excise tax imposed by Section 4999 of the Code. 
 (f)        No
Mitigation.  Except as provided in Section 7(a)(iii), Executive shall not be required to mitigate the amount of any payment provided for in this Section 7 by seeking other employment or otherwise, nor shall the amount of any
payment or benefit provided for in this Section 7 be reduced by any compensation earned by Executive as the result of self-employment or by retirement benefits; provided, however, that loans, advances or other amounts owed by Executive to the
Company may be offset by the Company against amounts payable to Executive under this Section 7; provided, further, that, as provided in Section 7(a), Executive’s right to continued health care benefits following his or her termination
of employment will terminate on the date on which the applicable continuation period under COBRA expires. 

(g)        Return of the Company’s Property.  If Executive’s employment is
terminated for any reason, the Company shall have the right, at its option, to require Executive to vacate his offices prior to or on the effective date of termination and to cease all activities on the Company’s behalf. Upon the termination of
his employment in any manner, as a condition to Executive’s receipt of any post termination benefits described in this Agreement, Executive shall immediately surrender to the Company all lists, books and records of, or in connection with, the
Company’s business, and all other property belonging to the Company, it being distinctly understood that all such lists, books and records, and other documents, are the property of the Company. Executive shall deliver to the Company a signed
statement certifying compliance with this Section 7(g) prior to the receipt of any post-termination benefits described in this Agreement. 

(h)        Definitions.  For purposes of this Agreement, the following terms shall
have the following meanings: 
 (i)        “Cause” shall mean any
of the following: (i) any act of personal dishonesty taken by Executive in connection with Executive’s responsibilities to the Company or 

  
 7 

 
any successor or parent or subsidiary thereof which is materially injurious to the Company or any successor or parent or subsidiary thereof; (ii) Executive’s conviction of a felony;
(iii) a willful act by Executive which constitutes gross misconduct and is materially injurious to the Company or any successor or parent or subsidiary thereof; (iv) Executive’s willful and material breach of a material obligation or
material duty under this Agreement, the Company’s Confidentiality and Proprietary Rights Agreement or the Company’s written employment or other written policies that have previously been furnished to Executive, which breach is not cured
within thirty (30) days after written notice thereof is received by Executive; (v) Executive’s failure to comply with reasonable directives of the Board that are consistent with Executive’s job duties (which directives are not in
conflict with applicable law), which failure is not cured within thirty (30) days after written notice thereof is received by Executive; or (vi) Executive’s misappropriation of any material property, including but not limited to
intellectual property, of the Company or any successor or parent or subsidiary thereof. 

(ii)          “Change in Control” means and includes each
of the following: 
 (A)       the acquisition, directly or indirectly, by any
“person” or “group” (as those terms are defined in Sections 3(a)(9), 13(d), and 14(d) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the rules thereunder) of “beneficial
ownership” (as determined pursuant to Rule 13d-3 under the Exchange Act) of securities entitled to vote generally in the election of directors (“voting securities”) of the Company that represent fifty percent (50%) or more of the
combined voting power of the Company’s then outstanding voting securities, other than: 

(1)        an acquisition by a trustee or other fiduciary holding securities under
any employee benefit plan (or related trust) sponsored or maintained by the Company or any person controlled by the Company or by any employee benefit plan (or related trust) sponsored or maintained by the Company or any person controlled by the
Company, or 
 (2)        an acquisition of voting securities by the Company or a
corporation owned, directly or indirectly, by the stockholders of the Company in substantially the same proportions as their ownership of the stock of the Company, or 

(3)        an acquisition of voting securities pursuant to a transaction described
in subsection (C) below that would not be a Change in Control under subsection (C); 
 Notwithstanding the foregoing, the following
event shall not constitute an “acquisition” by any person or group for purposes of this Section 7(h)(ii): an acquisition of the Company’s securities by the Company which causes the Company’s voting securities beneficially
owned by a person or group to represent fifty percent (50%) or more of the combined voting power of the Company’s then outstanding voting securities; provided, however, that if a person or group shall become the beneficial owner of
fifty percent (50%) or more of the combined voting power of the Company’s then outstanding voting securities by reason of share acquisitions by the Company as described above and shall, after such share acquisitions by the Company, become
the beneficial owner of any additional voting securities of the Company, then such acquisition shall constitute a Change in Control; or 

  
 8 

 (B)        during any period of two
consecutive years, individuals who, at the beginning of such period, constitute the Board together with any new director(s) (other than a director designated by a person who shall have entered into an agreement with the Company to effect a
transaction described in subsections (A) or (C) of this Section 7(h)(ii)) whose election by the Board or nomination for election by the Company’s stockholders was approved by a vote of at least two-thirds of the directors then
still in office who either were directors at the beginning of the two year period or whose election or nomination for election was previously so approved, cease for any reason to constitute a majority thereof; or 

(C)         the consummation by the Company (whether directly involving the
Company or indirectly involving the Company through one or more intermediaries) of a merger, consolidation, reorganization, or business combination, a sale or other disposition of all or eighty-five percent (85%) or more of the Company’s
assets, or the acquisition of assets or stock of another entity, in each case, other than a transaction 

(1)        which results in the Company’s voting securities outstanding
immediately before the transaction continuing to represent (either by remaining outstanding or by being converted into voting securities of the Company or the person that, as a result of the transaction, controls, directly or indirectly, the Company
or owns, directly or indirectly, all or substantially all of the Company’s assets or otherwise succeeds to the business of the Company (the Company or such person, the “Successor Entity”)) directly or indirectly, at least fifty
percent (50%) of the combined voting power of the Successor Entity’s outstanding voting securities immediately after the transaction, and 

(2)        after which no person or group beneficially owns voting securities
representing fifty percent (50%) or more of the combined voting power of the Successor Entity; provided however, that no person or group shall be treated for purposes of this paragraph (iii) as beneficially owning fifty percent
(50%) or more of combined voting power of the Successor Entity solely as a result of the voting power held in the Company prior to the consummation of the transaction; or 

(D)         the Company’s stockholders approve a liquidation or
dissolution of the Company. 
 For purposes of subsection (A) above, the calculation of voting power shall be made as
if the date of the acquisition were a record date for a vote of the Company’s stockholders, and for purposes of subsection (C) above, the calculation of voting power shall be made as if the date of the consummation of the transaction were
a record date for a vote of the Company’s stockholders. 
 Notwithstanding the foregoing, a transaction shall not
constitute a “Change in Control if: (A) its sole purpose is to change the state of the Company’s incorporation; (B) its sole purpose is to create a holding company that will be owned in substantially the same proportions by the
persons who held the Company’s securities immediately before such transaction; (C) it constitutes the Company’s initial public offering of its securities; or (D) it is a transaction effected primarily for the purpose of financing
the Company with cash (as determined by the Administrator in its discretion and without regard to whether such transaction is effectuated by a merger, equity financing or otherwise). 

  
 9 

 The Board shall have the ministerial authority to determine whether a Change in
Control has occurred pursuant to the above definition, and the date of the occurrence of such Change in Control and any incidental matters relating thereto. 

Notwithstanding the foregoing, a transaction or event shall be a “Change in Control” only if such transaction or
event constitutes a “change in control event,” as defined in Treasury Regulation Section 1.409A-3(i)(5), with respect to Executive. 

(iii)        “Disability” means the inability of Executive, in the
opinion of a qualified physician acceptable to the Company, to perform the major duties of Executive’s position with the Company or any parent or subsidiary or successor because of the sickness or injury of Executive for more than 90
consecutive days or more than 120 days in a 12 month period. 

(iv)        “Separation from Service” shall mean Executive’s
separation from service, as defined in Treasury Regulation Section 1.409A-1(h), with respect to the Company (and the service recipient, as defined in Treasury Regulation Section 1.409A-1(g), that includes the Company). 

(i)         Best Pay Provision.  If any payment or benefit Executive would
receive under this Agreement, when combined with any other payment or benefit Executive receives in connection with a Change in Control (“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 such Payment shall be either (x) the full amount of such Payment
or (y) such lesser amount (with cash payments being reduced before stock option compensation) as would result in no portion of the Payment being subject to the Excise Tax, whichever of the foregoing amounts, taking into account the applicable
federal, state and local employment taxes, income taxes, and the Excise Tax, results in Executive’s receipt, on an after-tax basis, of the greater amount of the Payment notwithstanding that all or some portion of the Payment may be subject to
the Excise Tax, Employee will be responsible for all taxes associated with the Payment, All determinations required to be made under this Section 7(i), including whether and to what extent the Payments shall be reduced and the assumptions to be
utilized in arriving at such determination, shall be made by the nationally recognized certified public accounting firm used by the Company immediately prior to the effective date of the Change in Control or, if such firm declines to serve, such
other nationally recognized certified public accounting firm as may be designated by the Company (the “Accounting Firm”). The Accounting Firm shall provide detailed supporting calculations both to Executive and the Company at such
time as is requested by the Executive. All fees and expenses of the Accounting Firm shall be borne solely by the Executive. Any determination by the Accounting Firm shall be binding upon Executive and the Company. For purposes of making the
calculations required by this Section 7(i), the Accounting Firm may make reasonable assumptions and approximations concerning applicable taxes and may rely on reasonable, good-faith interpretations concerning the application of Sections 280G
and 4999 of the Code. 
 8.   No Conflict of Interest.  During Executive’s employment with the Company,
Executive shall not engage in any activity that creates an actual conflict of interest with the Company without the prior written consent of an authorized representative of the Board. Such work shall include, but is not limited to, directly
competing with the Company in any way, or acting as an officer, director, employee, consultant, stockholder, volunteer, lender, or agent of any business enterprise of the same nature as, or which is in direct competition with, the business in which
the Company is now engaged or in which the Company becomes engaged during Executive’s employment with the Company, as may be determined by the Board in its sole discretion. If the Company believes such a conflict exists during Executive’s
employment with the Company, the Company may ask Executive to choose to modify the scope of the 

  
 10 

 
other activity, discontinue the other activity, or resign employment with the Company, Moreover, during Executive’s employment with the Company, it shall not be a violation of this Agreement
for Executive to (a) serve on any civic or charitable boards or committees; (b) deliver lectures, fulfill teaching or speaking engagements; (c) manage personal investments; or (d) serve as a member of the board of directors of
one corporation (in addition to the Company) with the Board’s written approval, which shall not be unreasonably withheld provided, further, that any such activities must not materially interfere with Executive’s performance
of his duties and responsibilities under this Agreement. 
 9.    Confidentiality and Proprietary
Rights.  Executive and the Company have executed the Company’s Confidentiality and Proprietary Rights Agreement, a copy of which is attached to this Agreement as Exhibit B and incorporated herein by reference. 

10.  Non-Interference and Nonsolicitation.  Executive understands and agrees that the Company’s employees,
customers and partners and any information regarding the Company’s employees, customers and/or partners is confidential and constitutes trade secrets of the Company. Executive agrees that during his employment and for a period of one
(1) year (which period the Company acknowledges is less than that required under the Company’s Confidentiality and Proprietary Rights Agreement and which, notwithstanding anything to the contrary contained in the Company’s
Confidentiality and Proprietary Rights Agreement to which Executive, is a party, shall be the operative non-solicitation period for Executive) after termination of his employment, Executive will not, either directly or indirectly, separately or in
association with others use the Company’s confidential information or trade secrets to interfere with, impair, disrupt or damage the Company’s relationship or business with any of its customers or partners, either by soliciting or
encouraging others to solicit any of them for the purpose of diverting or taking away business from the Company. Additionally, notwithstanding any other provision of this Agreement, including the Company Confidentiality and Proprietary Rights
Agreement incorporated herein by reference, Executive agrees that during his employment and for a period of one (1) year after the termination of his employment, Executive will not, either directly or indirectly, separately or in association
with others: (a) interfere with, impair, disrupt or damage the Company’s relationship with any of its customers by soliciting or encouraging others to solicit any of them for the purpose of diverting or taking away business from the
Company; or (b) interfere with, impair, disrupt or damage the Company’s business by soliciting, encouraging or attempting to hire any of the Company’s employees or causing others to solicit or encourage any of the Company’s
employees to discontinue their employment with the Company. 
 11.  Remedies; Injunctive Relief.  The parties
acknowledge that a breach of the covenants contained in Sections 8, 9 and 10 would cause irreparable injury and agree that in the event of any such breach the nonbreaching party shall be entitled to seek temporary, preliminary and permanent
injunctive relief, as specified under Section 1281.8 of the California Code of Civil Procedure, without the necessity of proving actual damages or posting any bond or other security. In addition, the Company shall be entitled to cease all
severance payments to Executive in the event of his breach of Section 8, 9 or 10. 

12.  Indemnification.  Executive shall be entitled to indemnification as an officer of the Company as provided in
Article VIII of the Bylaws of the Company, without regard to any future changes in Executive’s assignment or position. In addition, to the extent the Company obtains insurance providing coverage or indemnification for other officers or
employees, or enters into any agreements with any other officers or employees which provide such officer or employee with rights to indemnification, Executive shall be included as a named insured in such policy and/or granted the same rights to
indemnification as are provided in such other agreements. 
 13.  Agreement to Arbitrate.  Any dispute, claim or
controversy based on, arising out of or relating to Executive’s employment or this Agreement shall be settled by final and binding arbitration in 

  
 11 

 
San Diego, California, before a single neutral arbitrator in accordance with the National Rules for the Resolution of Employment Disputes (the “Rules’’) of the American
Arbitration Association, and judgment on the award rendered by the arbitrator may be entered in any court having jurisdiction, Arbitration may be compelled pursuant to the California Arbitration Act (Code of Civil Procedure §§ 1280
et seq.). If the parties are unable to agree upon an arbitrator, one shall be appointed by the AAA in accordance with its Rules. Each party shall pay the fees of its own attorneys, the expenses of its witnesses and all other expenses
connected with presenting its case; however, Executive and the Company agree that, to the extent permitted by law, the arbitrator may, in his or her discretion, award reasonable attorneys’ fees to the prevailing party. Other costs of the
arbitration, including the cost of any record or transcripts of the arbitration, AAA’s administrative fees, the fee of the arbitrator, and all other fees and costs, shall be borne by the Company. This Section 13 is intended to be the
exclusive method for resolving any and all claims by the parties against each other for payment of damages under this Agreement or relating to Executive’s employment; provided, however, that neither this Agreement nor the
submission to arbitration shall limit the parties’ right to seek provisional relief, including without limitation injunctive relief, in any court of competent jurisdiction pursuant to California Code of Civil Procedure § 1281.8 or any
similar statute of an applicable jurisdiction. Seeking any such relief shall not be deemed to be a waiver of such party’s right to compel arbitration. Both Executive and the Company expressly waive their right to a jury trial. 

14.  General Provisions. 

14.1      Successors and Assigns.  The rights of the Company under this Agreement may, without
the consent of Executive, be assigned by the Company, in its sole and unfettered discretion, to any person, firm, corporation or other business entity which at any time, whether by purchase, merger or otherwise, directly or indirectly, acquires all
or substantially all of the assets or business of the Company. The Company will require any successor (whether direct or indirect, by purchase, merger or otherwise) to all or substantially all of the business or assets of the Company expressly to
assume and to agree to perform this Agreement in the same manner and to the same extent that the Company would be required to perform it if no such succession had taken place; provided, however, that no such assumption shall relieve
the Company of its obligations hereunder. As used in this Agreement, the “Company” shall mean the Company as hereinbefore defined and any successor to its business and/or assets as aforesaid which assumes and agrees to perform this
Agreement by operation of law or otherwise. Executive shall not be entitled to assign any of Executive’s rights or obligations under this Agreement. This Agreement shall inure to the benefit of and he enforceable by Executive’s personal or
legal representatives, executors, administrators, successors, heirs, distributees, devisees and legatees. If Executive should die while any amount is at such time payable to him hereunder, all such amounts, unless otherwise provided herein, shall be
paid in accordance with the terms of this Agreement to Executive’s devisee, legatee, or other designee or, if there be no such designee, to his estate, 

14.2      Waiver.  Either party’s failure to enforce any provision of this Agreement
shall not in any way be construed as a waiver of any such provision, or prevent that party thereafter from enforcing each and every other provision of this Agreement. 

14.3      Attorneys’ Fees.  Each side will bear its own attorneys’ fees in any
dispute unless a statutory section at issue, if any, authorizes the award of attorneys’ fees to the prevailing party. 

14.4      Severability.  In the event any provision of this Agreement is found to be
unenforceable by an arbitrator or court of competent jurisdiction, such provision shall be deemed modified to the extent necessary to allow enforceability of the provision as so limited, it being intended that the parties shall receive the benefit
contemplated herein to the fullest extent permitted by law. If a deemed modification is not satisfactory in the judgment of such arbitrator or court, the unenforceable provision shall be deemed deleted, and the validity and enforceability of the
remaining provisions shall not be affected thereby. 

  
 12 

 14.5      Interpretation; Construction.  The
headings set forth in this Agreement are for convenience only and shall not be used in interpreting this Agreement. This Agreement has been drafted by legal counsel representing the Company, but Executive has participated in the negotiation of its
terms. Furthermore, Executive acknowledges that Executive has had an opportunity to review and revise the Agreement and have it reviewed by legal counsel, if desired, and, therefore, the normal rule of construction to the effect that any ambiguities
are to be resolved against the drafting party shall not be employed in the interpretation of this Agreement. 

14.6      Tax Withholding.  The payments made pursuant to this Agreement shall be subject to
tax withholding and payroll deductions required by applicable law. 
 14.7      Governing
Law.  This Agreement will be governed by and construed in accordance with the laws of the United States and the State of California. Each party consents to the jurisdiction and venue of the state or federal courts in San Diego,
California, if applicable, in any action, suit, or proceeding arising out of or relating to this Agreement. 

14.8      Notices.  Any notice required or permitted by this Agreement, shall be in writing
and shall be delivered as follows with notice deemed given as indicated: (a) by personal delivery when delivered personally; (b) by overnight courier upon written verification of receipt; (c) by telecopy or facsimile transmission upon
acknowledgment of receipt of electronic transmission; or (d) by certified or registered mail, return receipt requested, upon verification of receipt. Notice shall be sent to Executive at the address set forth below and to the Company at its
principal place of business, or such other address as either party may specify in writing. 

14.9      Survival.  Sections 7 (“Severance”), 9 (“Confidentiality
and Proprietary Rights”), 10 (“Non-Interference and Nonsolicitation”), 11 (“Remedies; Injunctive Relief”), 12 (“Indemnification”), 13 (“Agreement to Arbitrate”) and 14
(“General Provisions”) of this Agreement shall survive termination of Executive’s employment by the Company. 

14.10    Entire Agreement.  This Agreement, the Company Confidentiality and Proprietary Rights Agreement
incorporated herein by reference and the Stock Option Agreement(s) referenced in Section 4.4 of this Agreement, together constitute the entire agreement between the parties relating to this subject matter and supersedes all prior or
simultaneous representations, discussions, negotiations, and agreements, whether written or oral. This Agreement may be amended or modified only with the written consent of Executive and an authorized representative of the Company. No oral waiver,
amendment or modification will be effective under any circumstances whatsoever. 
 14.11    Compliance with
Section 409A of the Internal Revenue Code.  The parties acknowledge and agree that, to the extent applicable, this Agreement shall be interpreted in accordance with, and the parties agree to use their best efforts to achieve
timely compliance with, Section 409A, and the Department of Treasury Regulations and other interpretive guidance issued thereunder, including, without limitation, any such regulations or other guidance that may be issued after the Effective
Date. Notwithstanding any provision of this Agreement to the contrary, in the event that the Company determines that any amounts payable hereunder would otherwise be taxable to Executive under Section 409A, the Company may adopt such limited
amendments to this Agreement and appropriate policies and procedures, including amendments and policies with retroactive effect, that the Company reasonably determines are necessary or appropriate to comply with the requirements of Section 409A
and thereby avoid the application of taxes under Section 409A. 

  
 13 

 14.12    Counterparts.  This Agreement may be executed in
multiple counterparts, each of which shall be deemed an original but all of which together shall constitute one and the same instrument. 

THE PARTIES TO THIS AGREEMENT HAVE READ THE FOREGOING AGREEMENT AND FULLY UNDERSTAND EACH AND EVERY PROVISION CONTAINED HEREIN. WHEREFORE, THE
PARTIES HAVE EXECUTED THIS AGREEMENT ON THE DATES SHOWN BELOW. 

 

					
		 		  	
	Dated:	 	 Jan 6 2013
	  	
			
		 		  	
		 		  	
		 		  	
			
	Dated:	 	1/6/2013	  	
		 		  	
		 		  	

 

									
		 	LAWSON MACARTNEY
		
		 	/s/ Lawson Macartney
		 	  
	  	
					
		 		 	    Address:	  	 	  	
		 		 		  	 	  	
		
		 	AMBRX, INC.
				
		 	By:	 	         /s/ John D. Diekman
	  	

									
		 	Name:	 	 John D. Diekman
	  	

									
		 	Title:	 	 Chairman
	  	

 
 

  
 14 

 SCHEDULE 1 

TOTAL EQUITY OF THE COMPANY ON A FULLY DILUTED BASIS 

AS OF THE EMPLOYMENT COMMENCEMENT DATE 

[                      
  ] Shares 

 AMBRX, INC. 

Capitalization Table (DRAFT) 
 As of
12/31/2012 
  

																																													
	 	 	COMMON STOCK	 	 	PREFERRED STOCK	 	 	  
	 
	Holder Name	 	  Common
  Stock	 	 	    Options    	 	 	    Series A  	 	 	Series A-2    	 	 	Series B	 	 	Series C -
First
Closing	 	 	Series C -
Second
Closing	 	 	Series
D-1	 	 	
  Aggregate  
  Common  
  Stock  

  upon  
  conversion  
  of  
  preferred  
	 	 	  Total  
  Shares  	 	 	    Fully    
    Diluted    
    Ownership    	 
		 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
												
	 Tavistock Life Sciences
	 	 	166,666	  	 				 	 	3,835,133	  	 	 	3,500,000	  	 				 	 	3,356,675	  	 	 	2,797,229	  	 				 	 	13,489,037	  	 	 	13,655,703	  	 	 	16.4412%	  
	 5 AM Ventures LLC
	 	 	166,666	  	 				 	 	1,459,908	  	 	 	1,195,833	  	 				 	 	681,818	  	 	 	568,182	  	 				 	 	3,905,741	  	 	 	4,072,407	  	 	 	4.9031%	  
	 5 AM Co-Investors LLC
	 				 				 	 	208,559	  	 	 	170,834	  	 				 	 	97,402	  	 	 	81,169	  	 				 	 	557,964	  	 	 	557,964	  	 	 	0.6718%	  
	 Versant Venture Capital II, L.P.
	 				 				 	 	1,459,265	  	 	 	1,329,552	  	 				 	 	1,276,208	  	 	 	1,053,506	  	 				 	 	5,128,531	  	 	 	5,128,531	  	 	 	6.1747%	  
	 Versant Side Fund II, L.P.
	 				 				 	 	13,042	  	 	 	11,883	  	 				 	 	11,406	  	 	 	9,505	  	 				 	 	45,536	  	 	 	45,836	  	 	 	0.0552%	  
	 Versant Affiliates Fund ll-A, L.P.
	 				 				 	 	27,683	  	 	 	25,231	  	 				 	 	24,219	  	 	 	20,182	  	 				 	 	97,325	  	 	 	97,325	  	 	 	0.1172%	  
	 Aravis Venture I, L.P.
	 				 				 	 	666,667	  	 	 	428,001	  	 				 	 	311,689	  	 	 	259,740	  	 				 	 	1,666,097	  	 	 	1,666,097	  	 	 	2.0058%	  
	 Maverick Capital
	 				 				 				 	 	6,666,666	  	 				 	 	3,050,774	  	 	 	2,542,311	  	 				 	 	12,259,751	  	 	 	12,259,751	  	 	 	14.7605%	  
	 Apposite
	 				 				 				 				 				 	 	3,677,922	  	 	 	3,064,935	  	 				 	 	6,742,857	  	 	 	6,742,357	  	 	 	8.1183%	  
	 CMEA Ventures
	 				 				 	 	133,333	  	 	 	933,333	  	 				 	 	488,123	  	 	 	406,770	  	 				 	 	1,961,559	  	 	 	1,961,559	  	 	 	2.3617%	  
	 Glynn Capital
	 				 				 				 				 				 	 	623,377	  	 	 	519,480	  	 				 	 	1,142,857	  	 	 	1,142,857	  	 	 	1.3760%	  
	 DOW
	 				 				 				 				 				 	 	779,221	  	 	 	649,350	  	 				 	 	1,428,571	  	 	 	1,428,571	  	 	 	1.7200%	  
	 Healthcare Private Equity Limited Partnership
	 				 				 				 				 				 	 	935,065	  	 	 	779,221	  	 				 	 	1,714,286	  	 	 	1,714,286	  	 	 	2.0640%	  
	 Twilight Venture Partners
	 				 				 				 	 	73,600	  	 				 	 	33,681	  	 	 	26,067	  	 				 	 	135,348	  	 	 	135,348	  	 	 	0.1630%	  
	 Cornelius Family
	 				 				 				 	 	193,067	  	 				 	 	88,350	  	 	 	73,626	  	 				 	 	355,043	  	 	 	355,043	  	 	 	0.4275%	  
	 Alexandria Real Estate Equities
	 				 				 				 	 	333,333	  	 				 	 	152,539	  	 	 	127,115	  	 				 	 	612,987	  	 	 	612,987	  	 	 	0.7380%	  
	 Friends & Family
	 				 				 	 	533,333	  	 	 	771,999	  	 				 	 	464,827	  	 	 	386,086	  	 				 	 	2,156,245	  	 	 	2,156,245	  	 	 	2.5981%	  
	 Roche Finance Ltd.
	 				 				 				 				 	 	2,360,952	  	 	 	1,089,562	  	 	 	907,968	  	 				 	 	4,378,482	  	 	 	4,378,482	  	 	 	5.2716%	  
	 Merck Serono International
	 				 				 				 				 				 				 				 	 	3,649,635	  	 	 	3,649,635	  	 	 	3,649,635	  	 	 	4.3941%	  
	 TSRI
	 	 	500,000	  	 				 				 				 				 				 				 				 				 	 	500,000	  	 	 	0.6020%	  
	 Schultz / DiMarchi / Transferees/ Kaldor/ Watanabe
	 	 	3,606,892	  	 				 				 				 				 				 				 				 				 	 	3,606,892	  	 	 	4.3426%	  
	 Employees / Consultants Granted or Promised
	 				 	 	12,571,231	  	 				 				 				 				 				 				 				 	 	12,571,231	  	 	 	15.1355%	  
	 Lawson McCartney (Service Based Vesting Options)
	 				 	 	3,322,300	  	 				 				 				 				 				 				 				 	 	3,322,300	  	 	 	4.0000%	  
	 Lawson McCartney (Performance Based Vesting Options assumes return to investors of > $420M vs IPO)
	 				 	 	1,245,900	  	 				 				 				 				 				 				 				 	 	1,245,900	  	 	 	5000%	  
	 Remaining Stock Option Pool Balance
	 				 	 	50,000	  	 				 				 				 				 				 				 				 	 	50,000	  	 	 	0.0502%	  
		 				 				 				 				 				 				 				 				 				 				 			
		 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
	 TOTALS
	 	 	    4,440,224	  	 	 	    17,189,431	  	 	 	    8,336,933	  	 	 	15,833,332	  	 	 	2,380,952	  	 	 	17,142,858	  	 	 	14,284,442	  	 	 	3,649,635	  	 	 	61,428,152	  	 	 	83,057,807	  	 	 	100.00%	  
		 	  
	  
	 	 	  
	  
	 	 	  
	  
	 
		 				 				 	 	$1.50  	  	 	 	$1.50  	  	 	 	$2.10  	  	 	 	$1.75  	  	 	 	$1.75  	  	 	 	$2.74  	  	 				 				 			

  

 EXHIBIT A 

GENERAL RELEASE OF CLAIMS 

This General Release of Claims (“Release”) is entered into as of this
           day of                 ,         , between
Lawson Macartney (“Executive”), and Ambrx, Inc., a Delaware corporation (the “Company”) (collectively referred to herein as the “Parties”). 

WHEREAS, Executive and the Company are parties to that certain Executive Employment Agreement dated as of
                , 2012 (the “Agreement”); 

WHEREAS, the Parties agree that Executive is entitled to certain severance benefits under the Agreement, subject to Executive’s execution
of this Release; and 
 WHEREAS, the Company and Executive now wish to fully and finally to resolve all matters between them. 

NOW, THEREFORE, in consideration of, and subject to, the severance benefits payable to Executive pursuant to the Agreement, the adequacy of
which is hereby acknowledged by Executive, and which Executive acknowledges that he would not otherwise be entitled to receive, Executive and the Company hereby agree as follows: 

1.          General Release of Claims by Executive. 

(a)        Executive, on behalf of himself and his executors, heirs, administrators, representatives
and assigns, hereby agrees to release and forever discharge the Company and all predecessors, successors and their respective parent corporations, affiliates, related, and/or subsidiary entities, and all of their past and present investors,
directors, shareholders, officers, general or limited partners, employees, attorneys, agents and representatives, and the employee benefit plans in which Executive is or has been a participant by virtue of his employment with or service to the
Company (collectively, the “Company Releasees”), from any and all claims, debts, demands, accounts, judgments, rights, causes of action, equitable relief, damages, costs, charges, complaints, obligations, promises, agreements,
controversies, suits, expenses, compensation, responsibility and liability of every kind and character whatsoever (including attorneys’ fees and costs), whether in law or equity, known or unknown, asserted or unasserted, suspected or
unsuspected (collectively, “Claims”), which Executive has or may have had against such entities based on any events or circumstances arising or occurring on or prior to the date hereof or on or prior to the date hereof, arising
directly or indirectly out of, relating to, or in any other way involving in any manner whatsoever Executive’s employment by or service to the Company or the termination thereof, including any and all claims arising under federal, state, or
local laws relating to employment, including without limitation claims of wrongful discharge, breach of express or implied contract, fraud, misrepresentation, defamation, or liability in tort, and claims of any kind that may be brought in any court
or administrative agency including, without limitation, claims under Title VII of the Civil Rights Act of 1964, as amended, 42 U.S.C. Section 2000, et seq.; the Americans with Disabilities Act, as amended, 42 U.S.C. § 12101
et seq.; the Rehabilitation Act of 1973, as amended, 29 U.S.C. § 701 et seq.; the Civil Rights Act of 1866, and the Civil Rights Act of 1991; 42 U.S.C. Section 1981, et seq.; the Age Discrimination
in Employment Act, as amended, 29 U.S.C. Section 621, et seq. (the “ADEA”); the Equal Pay Act, as amended, 29 U.S.C. Section 206(d); regulations of the Office of Federal Contract Compliance, 41 C.F.R.
Section 60, et seq.; the Family and Medical Leave Act, as amended, 29 U.S.C. § 2601 et seq.; the Fair Labor Standards Act of 1938, as amended, 29 U.S.C. § 201 et seq.; the Employee Retirement
Income Security Act, as amended, 29 U.S.C. § 1001 et seq.; and the California Fair Employment and Housing Act, California Government Code Section 12940, et seq. 

  
 A-1 

 Notwithstanding the generality of the foregoing, Executive does not release the following claims:

 (i)          Claims for unemployment compensation or any state
disability insurance benefits pursuant to the terms of applicable state law; 

(ii)         Claims for workers’ compensation insurance benefits under the
terms of any worker’s compensation insurance policy or fund of the Company; 

(iii)        Claims pursuant to the terms and conditions of the federal law known as
COBRA; 
 (iv)        Claims for indemnity under the bylaws of the Company, as
provided for by Delaware law or under any applicable insurance policy with respect to Executive’s liability as an employee, director or officer of the Company; 

(v)         Claims based on any right Executive may have to enforce the
Company’s executory obligations under the Agreement; and 
 (vi)        Claims
Executive may have to vested or earned compensation and benefits. 
 (b)         EXECUTIVE
ACKNOWLEDGES THAT HE HAS BEEN ADVISED OF AND IS FAMILIAR WITH THE PROVISIONS OF CALIFORNIA CIVIL CODE SECTION 1542, WHICH PROVIDES AS FOLLOWS: 

“A GENERAL RELEASE DOES NOT EXTEND TO CLAIMS WHICH THE CREDITOR DOES NOT KNOW OR SUSPECT TO EXIST IN HIS OR HER FAVOR AT THE TIME OF
EXECUTING THE RELEASE, WHICH, IF KNOWN BY HIM OR HER, MUST HAVE MATERIALLY AFFECTED HIS OR HER SETTLEMENT WITH THE DEBTOR.” 

BEING AWARE OF SAID CODE SECTION, EXECUTIVE HEREBY EXPRESSLY WAIVES ANY RIGHTS HE MAY HAVE THEREUNDER, AS WELL AS UNDER ANY OTHER STATUTES OR
COMMON LAW PRINCIPLES OF SIMILAR EFFECT. 
 (c)         Executive acknowledges that this
Release was presented to him on the date indicated above and that Executive is entitled to consider this Release until the twenty-first (21st) day after that date (the “Review Period”). Executive further acknowledges that the
Company has advised him that he is waiving his rights under the ADEA, and that Executive may obtain advice concerning this Release from an attorney of his choice, and Executive has had sufficient time to consider the terms of this Release. Executive
represents and acknowledges that if Executive executes this Release before the expiration of the Review Period, Executive does so knowingly, voluntarily, and upon the advice and with the approval of Executive’s legal counsel (if any), and that
Executive voluntarily waives any remaining consideration period. 
 (d)         Executive
understands that after executing this Release, Executive has the right to revoke it within seven (7) days after his execution of it. Executive understands that this Release will not become effective and enforceable unless the seven (7) day
revocation period passes and Executive does not revoke the Release in writing. Executive understands that this Release may not be revoked after the seven (7) day revocation period has passed. Executive also understands that any revocation of
this Release must be made in writing and delivered to the Company at its principal place of business within the seven (7) day period. 

  
 A-2 

 (e)        Executive understands that this Release shall
become effective, irrevocable, and binding upon Executive on the eighth (8th) day after my execution of it, so long as Executive has not revoked it within the time period and in the manner
specified in clause (d) above. Executive further understands that Executive will not be given any severance benefits under the Agreement until the effective date of this Release. 

2.          No Assignment.  Executive represents and warrants to the
Company Releasees that there has been no assignment or other transfer of any interest in any Claim that Executive may have against the Company Releasees, or any of them. Executive agrees to indemnify and hold harmless the Company Releasees from any
liability, claims, demands, damages, costs, expenses and attorneys’ fees incurred as a result of any such assignment or transfer from Executive. 

3.          Paragraph Headings.  The headings of the several paragraphs in
this Release are inserted solely for the convenience of the Parties and are not a part of and are not intended to govern, limit or aid in the construction of any term or provision hereof. 

4.          Severability.  The invalidity or unenforceability of any
provision of this Release shall not affect the validity or enforceability of any other provision of this Release, which shall remain in full force and effect. 

5.          Governing Law and Venue.  This Release is to be governed by and
construed in accordance with the laws of the State of California applicable to contracts made and to be performed wholly within such State, and without regard to the conflicts of laws principles thereof. Any suit brought hereon shall be brought in
the state or federal courts sitting in San Diego, California, the Parties hereby waiving any claim or defense that such forum is not convenient or proper. Each party hereby agrees that any such court shall have in personam jurisdiction over it and
consents to service of process in any manner authorized by California law. 

6.          Counterparts.  This Release may be executed in several
counterparts, each of which shall be deemed to be an original but all of which together shall constitute one and the same instrument. 

7.          Construction.  The language in all pails of this Release shall
in all cases be construed simply, according to its fair meaning, and not strictly for or against any of the parties hereto. Without limitation, there shall be no presumption against any party on the ground that such party was responsible for
drafting this Release or any part thereof. 
 8.          Entire
Agreement.  This Release and the Agreement set forth the entire agreement of the Parties in respect of the subject matter contained herein and therein and supersede all prior agreements, promises, covenants, arrangements,
communications, representations or warranties, whether oral or written, by any officer, employee or representative of any party hereto, and any prior agreement of the Parties in respect of the subject matter contained herein. 

9.          Amendment.  No provision of this Release may be modified,
waived or discharged unless such waiver, modification or discharge is agreed to in writing and signed by Executive and such officer of the Company as may be specifically designated by the Board. 

10.        Understanding and Authority.  The Parties understand and agree that all
terms of this Release are contractual and are not a mere recital, and represent and warrant that they are competent to 

  
 A-3 

 
covenant and agree as herein provided. The Parties have carefully read this Release in its entirety; fully understand and agree to its terms and provisions; and intend and agree that it is final
and binding on all Parties. 
 IN WITNESS WHEREOF, and intending to be legally bound, the Parties have executed the foregoing Release as of
the date first written above. 
  
  

											
	EXECUTIVE	 		 	AMBRX, INC.
					
	 	 		 	By:	 	 	 	 
					
	Print Name:	 	 	 		 	Print Name:	 	 
						
		 		 		 	Title: 	 	 	 	 

  
 A-4 

 EXHIBIT B 

COMPANY CONFIDENTIALITY AND PROPRIETARY RIGHTS AGREEMENT 

 
 [Attached] 

 AMBRX, INC. 

CONFIDENTIALITY AND PROPRIETARY RIGHTS AGREEMENT 
  

1.          Definitions. 

1.1        “Company” means Ambrx, Inc., a Delaware corporation. 

1.2        “Party” means the person signing this Agreement, who is an employee of
Company. 
 1.3        “Invention” means inventions, discoveries, developments,
concepts, and ideas, whether patentable, copyrightable or otherwise registrable, including but not limited to assays, targets, receptors, mask works, trademarks, trade names, logos, Internet domain names, URLs, service marks, processes, designs,
techniques, data, formulas, formulations, know-how, improvements, research results, methods, formulas, techniques, devices, designs, programs (including computer programs), computer graphics, sources and object codes, other works of authorship,
organisms, plasmids, expression vectors, cell lines, chemical, biological and other material and their progeny, clones and derivatives, including but not limited to all genetically-engineered plants and animals, plans and designs for testing and
clinical trials, apparatus, products, as well as improvements thereof or know-how related thereto, relating to (i) any past or present business or activities of Company, or (ii) any reasonably anticipated business or activities of Company,
so long as such anticipated business or activities were communicated to or known to Party during his or her employment with Company. 

1.4        “Trade Secret” means, without limitation, any document or information
relating to the Company’s plans for research, development, manufacturing, engineering, new products, marketing and selling, business plans, proposed research or business affiliations, joint ventures or other collaborative or business
relationships, budgets and unpublished financial statements, licenses, prices and costs, supplier and customer information, and information regarding the skills and compensation of other employees of the Company, which documents or information have
been disclosed to Party or known to Party as a consequence of or through Party’s employment by Company (including documents, information or Inventions conceived, originated, discovered or developed by Party), which is not generally known in the
relevant trade or industry. The covenants of Sections 4 through 6 hereof shall terminate as to any Trade Secret which becomes known in the relevant trade or industry through no fault of Party. 

2.          Purpose.  In recognition of the need for Company to protect its
proprietary rights, and in consideration of the employment benefits to Party, and to memorialize and implement the previously existing oral agreements and implied agreement between Party and Company, this Agreement is being signed by Party. 

3.          Inventions. 

3.1        Disclosure.  Except for items excluded pursuant to Section 3.3,
Party shall disclose promptly to Company each Invention, whether or not reduced to practice, which is conceived or learned by Party (either alone or jointly with others) during the term of his or her employment with Company. Following any
termination of employment, Party shall promptly disclose in writing to Company any such Invention for which a written disclosure had not been given previously. 

  
 B-1 

 3.2        Company Property;
Assignment.  Except for items excluded pursuant to Section 3.3, Party acknowledges and agrees that all Inventions which are discovered, conceived, developed, made, produced or prepared by Party (alone or in conjunction with
others) during the duration of Party’s employment with Company shall be the sole properly of Company. Said property rights of Company include without limitation all domestic and foreign patent rights, rights of registration or other protection
under the patent and copyright laws, and all other rights pertaining to the Inventions. Party further agrees that all services, products and Inventions that directly or indirectly result from engagement with Company shall be deemed “works for
hire” as that term is defined in Title 17 of the United States Codes and accordingly all rights associated therewith shall vest in the Company. Notwithstanding the foregoing, Party hereby assigns to Company all of Party’s right, title and
interest in any such services, products and Inventions, in the event any such services, products and Inventions shall be determined not to constitute “works for hire.” To the extent any of the rights, title and interest to such services,
products and Inventions cannot be assigned to Company, Party hereby grants to Company an exclusive, royalty-free, fully paid-up, transferable, irrevocable, worldwide license (with the right authorize and grant sublicenses through multiple tiers of
sublicensees) to practice all applicable patent, copyright, trade secret or other proprietary or intellectual property rights relating to any such services, products or Inventions. 

3.3        Exclusion Notice.  Party has identified on Exhibit “A” attached
hereto all Inventions, applicable to the business of Company or relating in any way to Company’s business or demonstrably anticipated research and development or business, which were conceived, reduced to practice, created, derived, developed,
or made by Party prior to Party’s employment with Company (collectively, the “Prior Inventions”), and Party hereby represents that such list is complete. The assignment by Party of Inventions under this Agreement does not apply to
Prior Inventions made by Party. If there is no such list on Exhibit “A”, Party represents that Party has neither conceived, reduced to practice, created, derived, developed, or made any such Prior Inventions at the time of signing this
Agreement. Additionally, Party is not required to assign an idea or invention where the invention or idea meets all of the following criteria, namely that the invention or idea: (i) was created or conceived without the use of any of
Company’s equipment, supplies, facilities, or trade secret information, and (ii) was developed entirely on Party’s own time, and (iii) does not relate to the business of Company, and (iv) does not relate to Company’s
actual or demonstrably anticipated business, research or development, and (v) does not result from any work performed by Party for Company. 

3.4        Patents and Copyrights: Attorney-in-Fact.  Both before and after
termination of this Agreement (and with reasonable compensation to be paid by Company to Party for any activities after termination), Party agrees to assist Company to apply for, obtain and enforce patents on, and to apply for, obtain and enforce
copyright protection and registration of, the Inventions described in Section 3.2 in any and all countries. To that end, Party shall (at Company’s request and expense) without limitation, testify in any proceeding, and execute any
documents and assignments determined to be necessary or convenient for use in applying for, obtaining, registering and enforcing patent or copyright protection involving any of the Inventions. If Party is no longer employed by Company at the time
when Party’s assistance is needed, then Party and Company will cooperate to minimize any adverse impact on Party’s new employment, to the extent reasonably feasible. Party hereby irrevocably appoints Company, and its duly authorized
officers and agents, as Party’s agent and attorney-in-fact to act for and in behalf of Party in filing all patent applications, applications for copyright protection and registration, amendments, renewals, and all other appropriate documents in
any way related to the Inventions described in Section 3.2. 
 3.5        Maintenance of
Records.  Party agrees to keep and maintain adequate and current written records of all Inventions made by Party (solely or jointly with others) during the term of employment with Company. The Records will be in the form of notes,
sketches, drawings, and any other format that may be specified by Company. The records shall be maintained solely on the Company premises and shall be available to and remain the sole property of Company at all times. 

  
 B-2 

 4.          Trade Secrets. 

4.1        Acknowledgment of Proprietary Interest.  Party recognizes the proprietary
interest of Company in any Trade Secrets of Company, Party acknowledges and agrees that any and all Trade Secrets of Company shall be and are the property of Company, including without limitation, any such Trade Secrets which may be developed by
Party while Party remains employed by Company. 
 4.2        Covenant Not to Divulge Trade
Secrets.  Party acknowledges and agrees that Company is entitled to prevent the disclosure of Trade Secrets of Company. As a portion of the consideration for the employment of Party and for the compensation being paid to Party by
Company, Party agrees at all times during the term of the employment by Company and thereafter that Party will hold in strictest confidence, and not use, disclose, allow others to use, or allow to be disclosed to any person, organization, or
corporation, Trade Secrets of Company, including Trade Secrets developed by Party, other than disclosures to persons engaged by Company to further the business of Company, and other than use in the pursuit of the business of Company. 

4.3        Confidential Information of Others.  Party represents and warrants that
if Party has any confidential information belonging to others, Party will not knowingly use or disclose to Company any such information or documents, Party represents that, to the best of his or her knowledge, his or her employment with Company and
performance under this Agreement will not require Party to violate any obligation to or confidence with any other party. To the extent that Company receives from third parties their confidential or proprietary information subject to a duty on
Company to maintain the confidentiality of such information and to use it only for certain limited purposes, Party hereby agrees to hold all such confidential or proprietary information in the strictest confidence and not to disclose it to any
person, firm or corporation or to use it except as necessary in carrying out Party’s work for Company consistent with Company’s agreement with such third party. 

5.          No Adverse Use.  Party will not at any time during the term of
employment or thereafter use Company’s Trade Secrets or Inventions in any manner which may directly or indirectly have an adverse effect upon Company’s business, nor will Party perform any acts which would tend to reduce Company’s
proprietary value in Company’s Trade Secrets or Inventions. In addition, following any termination of Party’s employment, Party shall not engage, directly or indirectly, for the benefit of any other organization or Company, in any activity
or employment in the performance of which any of Company’s Trade Secrets obtained by Party during the course of his or her employment with Company would inevitably be used. These covenants shall not limit in any way Party’s obligation not
to use or disclose Company’s Trade Secrets as set forth in Section 4.2 above. 

6.          Return of Materials at Termination.  In the event of any
termination of Party’s employment, Party will promptly deliver to Company all materials (including, but not limited to, documents, drawings, models, apparatus, sketches, designs, laboratory notebooks, chemical and biological reagents (i.e.,
cell lines, vectors, plasmids and the like)), property, documents, data, and other information belonging to Company or pertaining to Trade Secrets or Inventions. Party shall not take any materials, property, documents or other information, or any
reproduction or excerpt thereof, belonging to Company or containing or pertaining to any Trade Secrets or Inventions. Upon termination of Party’s employment with Company, or at any time on the request of Company prior to termination, Party will
promptly (but no later than five days after the earlier of Party’s termination of employment or Company’s request) destroy or deliver to Company, at Company’s option (a) all materials furnished to Party by Company, (b) all
tangible media of expression which are in Party’s possession and which incorporate any 

  
 B-3 

 
Inventions or Trade Secrets or otherwise relate to the business of the Company and (c) written certification of Party’s compliance with his or her obligations under this Section in the
form attached hereto as Exhibit “B”. 
 7.          No Conflict of Interest
During Employment.  For the duration of the employment relationship (and any consulting relationship), Party agrees to not pursue any activities, directly or indirectly, that creates a conflict of interest with Company, including but
not limited to competing with the existing or planned business of Company. 

8.          Remedies Upon Breach.  In the event of a breach by either party
of the provisions in this Agreement, the nonbreaching party shall be entitled, if it so elects, to obtain injunctive relief as specified by California Civil Procedure Code section 1281.8, to enjoin the breaching party from violating any of the terms
of this Agreement, or to enforce the specific performance by the breaching party of any of the terms of this Agreement, but nothing herein contained shall be construed to prevent such remedy or combination of remedies as the nonbreaching party may
elect to invoke or pursue. The failure of either party to promptly institute legal action upon any breach of this Agreement shall not constitute a waiver of that or any other breach hereof. 

9.          Exception.  Notwithstanding the foregoing, if Party is required
by a binding court or governmental order to disclose specified information, and Company has been given reasonable advance written notice thereof to enable Company to oppose the same, then Party may make such limited disclosures as are necessary to
comply with said order. 
 10.        Applicable Provisions.  The undersigned Party
acknowledges and agrees that the foregoing provisions were understood and agreed to be applicable from the outset of Party’s association with Company, and that the foregoing provisions shall remain applicable for the duration of his or her
employment with Company, and thereafter to the extent applicable as set forth above. 

11.        No Solicitation.  Due to the confidential and proprietary nature of the
Inventions and Trade Secret to which Party has been exposed, or which Party will learn or be exposed to, while at Company, Party agrees that during the term of his or her employment with Company and for a period of two (2) years thereafter,
Party will not: (a) solicit, encourage, or cause others to solicit or encourage any employee of Company to terminate his or her employment with Company; or (b) interfere with, disrupt or impair, or cause others to interfere with, disrupt
or impair any of Company’s collaborations, business relationships or strategic partnerships with any third parties. 

12.        General Provisions. 

12.1    Entire Agreement.  This Agreement constitutes the entire agreement between the parties with
respect to its subject matter. This Agreement supersedes all prior or contemporaneous agreements or understandings, whether oral or written, on the same subjects, and this agreement cannot be modified unless such modification is in writing and
signed by me and by an authorized representative of the Company. 
 12.2    Severability.  In the
event any provision of this Agreement is found unenforceable by an arbitrator or court of competent jurisdiction, that provision will be deemed modified to the extent necessary to allow enforceability of the provision as so limited. 

12.3    Applicable Law; Jurisdiction.  This Agreement will be interpreted, construed and enforced under
the laws of the State of California. Each of the parties irrevocably consents to the exclusive personal jurisdiction of the federal and state courts located in California, as applicable, for the resolution of any matter arising out of or relating to
this Agreement. 

  
 B-4 

 I certify and acknowledge that I have carefully read all of the provisions of this Agreement and
that I understand and will fully and faithfully comply with such provisions. 
  
  

													
	DATED:	 	____________________	 		 	  
	 	
		 		 		 	Party’s Signature	 	
					
		 		 		 	  
	 	
		 		 		 	Party’s Name (Print)	 	
					
		 		 		 	AMBRX, INC.	 	
							
	DATED:	 	____________________	 		 	By:	 	 	 		 	
						
		 		 		 	  
	 		 	

 EXHIBIT A 

Inventions Owned by Party Prior to 

Commencement of Employment 
 (Attach
and sign additional sheets if necessary 
  
  

 
  

									
	DATED:	 	____________________	 		 	  
	 	
		 		 		 	Party’s Signature	 	
					
		 		 		 	  
	 	
		 		 		 	Party’s Name (Print)	 	

 EXHIBIT B 

TERMINATION CERTIFICATION 
 This
is to certify that I do not have in my possession, nor have I failed to return, any research materials or papers, laboratory notebooks, software programs, financial information, business or market information that falls within the definition of
“Trade Secret” in the Confidentiality and Proprietary Rights Agreement (the “Agreement”) between me and Ambrx, Inc. (“Ambrx”); or any reproductions or copies of the aforementioned items belonging to Ambrx. 

I further certify that I have complied with all the terms of the Agreement, including the provisions regarding the disclosure of Inventions
and the return of materials, property or Trade Secrets. 
 I further acknowledge and agree that, in compliance with the Agreement, I will
keep in confidence and trust all proprietary or confidential information, including but not limited to all Inventions and Trade Secrets, and I will not disclose or use the same without the prior written consent of Ambrx. 

I acknowledge that I have carefully read all of the provisions of this certification and that I understand and will fully and faithfully
comply with such provisions. 
  
  

									
	DATED:	 	____________________	 		 	  
	 	
		 		 		 	Party’s Signature	 	
					
		 		 		 	  
	 	
		 		 		 	Party’s Name (Print)	 	

  
 [Not to be completed until termination
of employment]

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