EX-10.3



 Exhibit 10.3 

TOCAGEN INC. 

2017 EQUITY INCENTIVE PLAN 

ADOPTED BY THE BOARD OF DIRECTORS:
                     

APPROVED BY THE STOCKHOLDERS:
                     
 IPO
DATE:                      

1. GENERAL. 

(a) Successor to and Continuation of Prior Plan. The Plan is intended as the successor to and continuation of the Tocagen Inc. 2009
Equity Incentive Plan, as amended (the “Prior Plan”). From and after 12:01 a.m. Pacific time on the IPO Date, no additional stock awards will be granted under the Prior Plan. All Awards granted on or after 12:01 a.m. Pacific
Time on the IPO Date will be granted under this Plan. All stock awards granted under the Prior Plan will remain subject to the terms of the Prior Plan. 

(i) Any shares that would otherwise remain available for future grants under the Prior Plan as of 12:01 a.m. Pacific
Time on the IPO Date (the “Prior Plan’s Available Reserve”) will cease to be available under the Prior Plan at such time. Instead, that number of shares of Common Stock equal to the Prior Plan’s Available Reserve
will be added to the Share Reserve (as further described in Section 3(a) below) and will be immediately available for grants and issuance pursuant to Stock Awards hereunder, up to the maximum number set forth in Section 3(a) below. 

(ii) In addition, from and after 12:01 a.m. Pacific time on the IPO Date, any shares subject, at such time, to
outstanding stock awards granted under the Prior Plan that (i) expire or terminate for any reason prior to exercise or settlement; (ii) are forfeited because of the failure to meet a contingency or condition required to vest such shares or
otherwise return to the Company; or (iii) are reacquired, withheld (or not issued) to satisfy a tax withholding obligation in connection with an award or to satisfy the purchase price or exercise price of a stock award (such shares the
“Returning Shares”) will immediately be added to the Share Reserve (as further described in Section 3(a) below) as and when such shares become Returning Shares, up to the maximum number set forth in Section 3(a)
below. 
 (b) Eligible Award Recipients. Employees, Directors and Consultants are eligible to receive Awards. 

(c) Available Awards. The Plan provides for the grant of the following Awards: (i) Incentive Stock Options,
(ii) Nonstatutory Stock Options, (iii) Stock Appreciation Rights, (iv) Restricted Stock Awards, (v) Restricted Stock Unit Awards, (vi) Performance Stock Awards, (vii) Performance Cash Awards, and (viii) Other Stock
Awards. 
 (d) Purpose. The Plan, through the grant of Awards, is intended to help the Company secure and retain the
services of eligible award recipients, provide incentives for such persons to exert maximum efforts for the success of the Company and any Affiliate, and provide 

  
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a means by which the eligible recipients may benefit from increases in value of the Common Stock. 

2. ADMINISTRATION. 

(a) Administration by Board. The Board will administer the Plan. The Board may delegate administration of the Plan to a
Committee or Committees, as provided in Section 2(c). 
 (b) Powers of Board. The Board will have the power,
subject to, and within the limitations of, the express provisions of the Plan: 
 (i) To determine: (A) who will
be granted Awards; (B) when and how each Award will be granted; (C) what type of Award will be granted; (D) the provisions of each Award (which need not be identical), including when a person will be permitted to exercise or otherwise
receive cash or Common Stock under the Award; (E) the number of shares of Common Stock subject to, or the cash value of, an Award; and (F) the Fair Market Value applicable to a Stock Award. 

(ii) To construe and interpret the Plan and Awards granted under it, and to establish, amend and revoke rules and
regulations for administration of the Plan and Awards. The Board, in the exercise of these powers, may correct any defect, omission or inconsistency in the Plan or in any Award Agreement or in the written terms of a Performance Cash Award, in a
manner and to the extent it will deem necessary or expedient to make the Plan or Award fully effective. 
 (iii) To
settle all controversies regarding the Plan and Awards granted under it. 
 (iv) To accelerate, in whole or in part,
the time at which an Award may be exercised or vest (or the time at which cash or shares of Common Stock may be issued in settlement thereof). 

(v) To suspend or terminate the Plan at any time. Except as otherwise provided in the Plan or an Award Agreement,
suspension or termination of the Plan will not materially impair a Participant’s rights under the Participant’s then-outstanding Award without the Participant’s written consent, except as provided in subsection (viii) below. 

(vi) To amend the Plan in any respect the Board deems necessary or advisable, including, without limitation, by
adopting amendments relating to Incentive Stock Options and certain nonqualified deferred compensation under Section 409A of the Code and/or bringing the Plan or Awards granted under the Plan into compliance with the requirements for Incentive
Stock Options or ensuring that they are exempt from, or compliant with, the requirements for nonqualified deferred compensation under Section 409A of the Code, subject to the limitations, if any, of applicable law. If required by applicable law
or listing requirements, and except as provided in Section 9(a) relating to Capitalization Adjustments, the Company will seek stockholder approval of any amendment of the Plan that (A) materially increases the number of shares of Common
Stock available for issuance under the Plan, (B) materially expands the class of individuals eligible to receive Awards under the Plan, (C) materially increases the benefits accruing to Participants under the Plan, (D) materially
reduces the price at which shares of 

  
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Common Stock may be issued or purchased under the Plan, (E) materially extends the term of the Plan, or (F) materially expands the types of Awards available for issuance under the Plan.
Except as otherwise provided in the Plan or an Award Agreement, no amendment of the Plan will materially impair a Participant’s rights under an outstanding Award without the Participant’s written consent. 

(vii) To submit any amendment to the Plan for stockholder approval, including, but not limited to, amendments to the
Plan intended to satisfy the requirements of (A) Section 162(m) of the Code regarding the exclusion of performance-based compensation from the limit on corporate deductibility of compensation paid to Covered Employees,
(B) Section 422 of the Code regarding “incentive stock options” or (C) Rule 16b-3. 
 (viii)
To approve forms of Award Agreements for use under the Plan and to amend the terms of any one or more Awards, including, but not limited to, amendments to provide terms more favorable to the Participant than previously provided in the Award
Agreement, subject to any specified limits in the Plan that are not subject to Board discretion; provided, however, that a Participant’s rights under any Award will not be impaired by any such amendment unless (A) the Company
requests the consent of the affected Participant, and (B) such Participant consents in writing. Notwithstanding the foregoing, (1) a Participant’s rights will not be deemed to have been impaired by any such amendment if the Board, in
its sole discretion, determines that the amendment, taken as a whole, does not materially impair the Participant’s rights, and (2) subject to the limitations of applicable law, if any, the Board may amend the terms of any one or more
Awards without the affected Participant’s consent (A) to maintain the qualified status of the Award as an Incentive Stock Option under Section 422 of the Code; (B) to change the terms of an Incentive Stock Option, if such change
results in impairment of the Award solely because it impairs the qualified status of the Award as an Incentive Stock Option under Section 422 of the Code; (C) to clarify the manner of exemption from, or to bring the Award into compliance
with, Section 409A of the Code; or (D) to comply with other applicable laws or listing requirements. 
 (ix)
Generally, to exercise such powers and to perform such acts as the Board deems necessary or expedient to promote the best interests of the Company and that are not in conflict with the provisions of the Plan or Awards. 

(x) To adopt such procedures and sub-plans as are necessary or appropriate to permit participation in the Plan by
Employees, Directors or Consultants who are foreign nationals or employed outside the United States (provided that Board approval will not be necessary for immaterial modifications to the Plan or any Award Agreement that are required for compliance
with the laws of the relevant foreign jurisdiction). 
 (xi) To effect, with the consent of any adversely affected
Participant, (A) the reduction of the exercise, purchase or strike price of any outstanding Stock Award; (B) the cancellation of any outstanding Stock Award and the grant in substitution therefor of a new (1) Option or SAR,
(2) Restricted Stock Award, (3) Restricted Stock Unit Award, (4) Other Stock Award, (5) cash and/or (6) other valuable consideration determined by the Board, in its sole discretion, with any such substituted award
(x) covering the same or a different number of shares of Common Stock as the cancelled Stock Award and (y) granted under the Plan or another equity 

  
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or compensatory plan of the Company; or (C) any other action that is treated as a repricing under generally accepted accounting principles. 

(c) Delegation to Committee. 

(i) General. The Board may delegate some or all of the administration of the Plan to a Committee or Committees. If
administration of the Plan is delegated to a Committee, the Committee will have, in connection with the administration of the Plan, the powers theretofore possessed by the Board that have been delegated to the Committee, including the power to
delegate to a subcommittee of the Committee any of the administrative powers the Committee is authorized to exercise (and references in this Plan to the Board will thereafter be to the Committee or subcommittee, as applicable). Any delegation of
administrative powers will be reflected in resolutions, not inconsistent with the provisions of the Plan, adopted from time to time by the Board or Committee (as applicable). The Board may retain the authority to concurrently administer the Plan
with the Committee and may, at any time, revest in the Board some or all of the powers previously delegated. 
 (ii)
Section 162(m) and Rule 16b-3 Compliance. The Committee may consist solely of two or more Outside Directors, in accordance with Section 162(m) of the Code, or solely of two or more Non-Employee Directors, in accordance with Rule 16b-3.

 (d) Delegation to an Officer. The Board may delegate to one (1) or more Officers the authority to do one or
both of the following (i) designate Employees who are not Officers to be recipients of Options and SARs (and, to the extent permitted by applicable law, other Stock Awards) and, to the extent permitted by applicable law, the terms of such
Awards, and (ii) determine the number of shares of Common Stock to be subject to such Stock Awards granted to such Employees; provided, however, that the Board resolutions regarding such delegation will specify the total number of shares
of Common Stock that may be subject to the Stock Awards granted by such Officer and that such Officer may not grant a Stock Award to himself or herself. Any such Stock Awards will be granted on the form of Stock Award Agreement most recently
approved for use by the Committee or the Board, unless otherwise provided in the resolutions approving the delegation authority. The Board may not delegate authority to an Officer who is acting solely in the capacity of an Officer (and not also as a
Director) to determine the Fair Market Value pursuant to Section 13(x)(iii) below. 
 (e) Effect of Board’s
Decision. All determinations, interpretations and constructions made by the Board in good faith will not be subject to review by any person and will be final, binding and conclusive on all persons. 

3. SHARES SUBJECT TO THE PLAN. 

(a) Share Reserve. Subject to Section 9(a) relating to Capitalization Adjustments, and the following sentence
regarding the annual increase, the aggregate number of shares of Common Stock that may be issued pursuant to Stock Awards will not exceed [                ] shares (the
“Share Reserve”), which number is the sum of (i) [                ] new shares, plus (ii) the number of shares subject to the
Prior Plan’s Available Reserve, plus (iii) the number of shares that are Returning Shares, as such shares become available from time to time. 

  
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 In addition, the Share Reserve will automatically increase on January 1st of each year, for a period of not more than ten years, commencing on January 1st of the year following the year in which the IPO Date occurs
and ending on (and including) January 1, [2027], in an amount equal to [    ]% of the total number of shares of Capital Stock outstanding on December 31st of the
preceding calendar year. Notwithstanding the foregoing, the Board may act prior to January 1st of a given year to provide that there will be no January 1st increase in the Share Reserve for such year or that the increase in the Share Reserve for such year will be a lesser number of shares of Common Stock than would otherwise occur pursuant to the
preceding sentence. 
 For clarity, the Share Reserve in this Section 3(a) is a limitation on the number of shares of
Common Stock that may be issued pursuant to the Plan. Accordingly, this Section 3(a) does not limit the granting of Stock Awards except as provided in Section 7(a). Shares may be issued in connection with a merger or acquisition as
permitted by NASDAQ Listing Rule 5635(c) or, if applicable, NYSE Listed Company Manual Section 303A.08, AMEX Company Guide Section 711 or other applicable rule, and such issuance will not reduce the number of shares available for issuance
under the Plan. 
 (b) Reversion of Shares to the Share Reserve. If a Stock Award or any portion thereof
(i) expires or otherwise terminates without all of the shares covered by such Stock Award having been issued or (ii) is settled in cash (i.e., the Participant receives cash rather than stock), such expiration, termination or
settlement will not reduce (or otherwise offset) the number of shares of Common Stock that may be available for issuance under the Plan. If any shares of Common Stock issued pursuant to a Stock Award are forfeited back to or repurchased by the
Company because of the failure to meet a contingency or condition required to vest such shares in the Participant, then the shares that are forfeited or repurchased will revert to and again become available for issuance under the Plan. Any shares
reacquired by the Company in satisfaction of tax withholding obligations on a Stock Award or as consideration for the exercise or purchase price of a Stock Award will again become available for issuance under the Plan. 

(c) Incentive Stock Option Limit. Subject to the provisions of Section 9(a) relating to Capitalization
Adjustments, the aggregate maximum number of shares of Common Stock that may be issued pursuant to the exercise of Incentive Stock Options will be [                ]
shares of Common Stock. 
 (d) Section 162(m) Limitations. Subject to the provisions of Section 9(a)
relating to Capitalization Adjustments, at such time as the Company may be subject to the applicable provisions of Section 162(m) of the Code, the following limitations shall apply. 

(i) A maximum of [                ]
shares of Common Stock subject to Options, SARs and Other Stock Awards whose value is determined by reference to an increase over an exercise or strike price of at least 100% of the Fair Market Value on the date the Stock Award is granted may be
granted to any one Participant during any one calendar year. Notwithstanding the foregoing, if any additional Options, SARs or Other Stock Awards whose value is determined by reference to an increase over an exercise or strike price of at least 100%
of the Fair Market Value on the date the Stock Award are granted to any Participant during any calendar year, compensation attributable to the exercise of such additional Stock Awards will not satisfy the requirements to be considered
“qualified performance-based compensation” under 

  
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Section 162(m) of the Code unless such additional Stock Award is approved by the Company’s stockholders. 

(ii) A maximum of [                ]
shares of Common Stock subject to Performance Stock Awards may be granted to any one Participant during any one calendar year (whether the grant, vesting or exercise is contingent upon the attainment during the Performance Period of the Performance
Goals). 
 (iii) A maximum of $[        ] may be granted as a Performance
Cash Award to any one Participant during any one calendar year. 
 (e) Limitation on Grants to Non-Employee Directors.
The maximum number of shares of Common Stock subject to Stock Awards granted under the Plan or otherwise during any one calendar year to any Non-Employee Director, taken together with any cash fees paid by the Company to such Non-Employee
Director during such calendar year for service on the Board, will not exceed $[        ] in total value (calculating the value of any such Stock Awards based on the grant date fair value of such Stock Awards
for financial reporting purposes), or, with respect to the calendar year in which a Non-Employee Director is first appointed or elected to the Board, $[        ]. The Board may make exceptions to the
applicable limit in this Section 3(e) for individual Non-Employee Directors in extraordinary circumstances, as Board may determine in its discretion, provided that the Non-Employee Director receiving such additional compensation may not
participate in the decision to award such compensation. 
 (f) Source of Shares. The stock issuable under the Plan
will be shares of authorized but unissued or reacquired Common Stock, including shares repurchased by the Company on the open market or otherwise. 

4. ELIGIBILITY. 

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

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

  
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 5. PROVISIONS RELATING TO OPTIONS
AND STOCK APPRECIATION RIGHTS. 
 Each Option or SAR will be
in such form and will contain such terms and conditions as the Board deems appropriate. All Options will be separately designated Incentive Stock Options or Nonstatutory Stock Options at the time of grant, and, if certificates are issued, a separate
certificate or certificates will be issued for shares of Common Stock purchased on exercise of each type of Option. If an Option is not specifically designated as an Incentive Stock Option, or if an Option is designated as an Incentive Stock Option
but some portion or all of the Option fails to qualify as an Incentive Stock Option under the applicable rules, then the Option (or portion thereof) will be a Nonstatutory Stock Option. The provisions of separate Options or SARs need not be
identical; provided, however, that each Award Agreement will conform to (through incorporation of provisions hereof by reference in the applicable Award Agreement or otherwise) the substance of each of the following provisions: 

(a) Term. Subject to the provisions of Section 4(b) regarding Ten Percent Stockholders, no Option or SAR will be
exercisable after the expiration of ten years from the date of its grant or such shorter period specified in the Award Agreement. 

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

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

(i) by cash, check, bank draft or money order payable to the Company; 

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

(iii) by delivery to the Company (either by actual delivery or attestation) of shares of Common Stock; 

(iv) if an Option is a Nonstatutory Stock Option, by a “net exercise” arrangement pursuant to which the
Company will reduce the number of shares of Common Stock 

  
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issuable upon exercise by the largest whole number of shares with a Fair Market Value that does not exceed the aggregate exercise price; provided, however, that the Company will accept a
cash or other payment from the Participant to the extent of any remaining balance of the aggregate exercise price not satisfied by such reduction in the number of whole shares to be issued. Shares of Common Stock will no longer be subject to an
Option and will not be exercisable thereafter to the extent that (A) shares issuable upon exercise are used to pay the exercise price pursuant to the “net exercise,” (B) shares are delivered to the Participant as a result of such
exercise, and (C) shares are withheld to satisfy tax withholding obligations; or 
 (v) in any other form of
legal consideration that may be acceptable to the Board and specified in the applicable Award Agreement. 
 (d) Exercise
and Payment of a SAR. To exercise any outstanding SAR, the Participant must provide written notice of exercise to the Company in compliance with the provisions of the Stock Appreciation Right Agreement evidencing such SAR. The appreciation
distribution payable on the exercise of a SAR will be not greater than an amount equal to the excess of (A) the aggregate Fair Market Value (on the date of the exercise of the SAR) of a number of shares of Common Stock equal to the number of
Common Stock equivalents in which the Participant is vested under such SAR, and with respect to which the Participant is exercising the SAR on such date, over (B) the aggregate strike price of the number of Common Stock equivalents with respect
to which the Participant is exercising the SAR on such date. The appreciation distribution may be paid in Common Stock, in cash, in any combination of the two or in any other form of consideration, as determined by the Board and contained in the
Award Agreement evidencing such SAR. 
 (e) Transferability of Options and SARs. The Board may, in its sole
discretion, impose such limitations on the transferability of Options and SARs as the Board will determine. In the absence of such a determination by the Board to the contrary, the following restrictions on the transferability of Options and SARs
will apply: 
 (i) Restrictions on Transfer. An Option or SAR will not be transferable except by will or by the laws
of descent and distribution (or pursuant to subsections (ii) and (iii) below), and will be exercisable during the lifetime of the Participant only by the Participant. The Board may permit transfer of the Option or SAR in a manner that is
not prohibited by applicable tax and securities laws. Except as explicitly provided in the Plan, neither an Option nor a SAR may be transferred for consideration. 

(ii) Domestic Relations Orders. Subject to the approval of the Board or a duly authorized Officer, an Option or SAR may
be transferred pursuant to the terms of a domestic relations order, official marital settlement agreement or other divorce or separation instrument as permitted by Treasury Regulations Section 1.421-1(b)(2). If an Option is an Incentive Stock
Option, such Option may be deemed to be a Nonstatutory Stock Option as a result of such transfer. 
 (iii) Beneficiary
Designation. Subject to the approval of the Board or a duly authorized Officer, a Participant may, by delivering written notice to the Company, in a form approved by the Company (or the designated broker), designate a third party who, on the
death 

  
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of the Participant, will thereafter be entitled to exercise the Option or SAR and receive the Common Stock or other consideration resulting from such exercise. In the absence of such a
designation, upon the death of the Participant, the executor or administrator of the Participant’s estate will be entitled to exercise the Option or SAR and receive the Common Stock or other consideration resulting from such exercise. However,
the Company may prohibit designation of a beneficiary at any time, including due to any conclusion by the Company that such designation would be inconsistent with the provisions of applicable laws. 

(f) Vesting Generally. The total number of shares of Common Stock subject to an Option or SAR may vest and become
exercisable in periodic installments that may or may not be equal. The Option or SAR may be subject to such other terms and conditions on the time or times when it may or may not be exercised (which may be based on the satisfaction of Performance
Goals or other criteria) as the Board may deem appropriate. The vesting provisions of individual Options or SARs may vary. The provisions of this Section 5(f) are subject to any Option or SAR provisions governing the minimum number of shares of
Common Stock as to which an Option or SAR may be exercised. 
 (g) Termination of Continuous Service. Except as
otherwise provided in the applicable Award Agreement or other agreement between the Participant and the Company, if a Participant’s Continuous Service terminates (other than for Cause and other than upon the Participant’s death or
Disability), the Participant may exercise his or her Option or SAR (to the extent that the Participant was entitled to exercise such Award as of the date of termination of Continuous Service) within the period of time ending on the earlier of
(i) the date three months following the termination of the Participant’s Continuous Service (or such longer or shorter period specified in the applicable Award Agreement), and (ii) the expiration of the term of the Option or SAR as
set forth in the Award Agreement. If, after termination of Continuous Service, the Participant does not exercise his or her Option or SAR (as applicable) within the applicable time frame, the Option or SAR will terminate. 

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

  
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 (i) Disability of Participant. Except as otherwise provided in the
applicable Award Agreement or other agreement between the Participant and the Company, if a Participant’s Continuous Service terminates as a result of the Participant’s Disability, the Participant may exercise his or her Option or SAR (to
the extent that the Participant was entitled to exercise such Option or SAR as of the date of termination of Continuous Service), but only within such period of time ending on the earlier of (i) the date 12 months following such termination of
Continuous Service (or such longer or shorter period specified in the Award Agreement), and (ii) the expiration of the term of the Option or SAR as set forth in the Award Agreement. If, after termination of Continuous Service, the Participant
does not exercise his or her Option or SAR within the applicable time frame, the Option or SAR (as applicable) will terminate. 

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

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

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

  
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non-exempt employee in connection with the exercise, vesting or issuance of any shares under any other Stock Award will be exempt from the employee’s regular rate of pay, the provisions of
this Section 5(l) will apply to all Stock Awards and are hereby incorporated by reference into such Stock Award Agreements. 
 6.
PROVISIONS OF STOCK AWARDS OTHER THAN OPTIONS AND SARS. 

(a) Restricted Stock Awards. Each Restricted Stock Award Agreement will be in such form and will contain such terms and
conditions as the Board will deem appropriate. To the extent consistent with the Company’s bylaws, at the Board’s election, shares of Common Stock may be (x) held in book entry form subject to the Company’s instructions until any
restrictions relating to the Restricted Stock Award lapse; or (y) evidenced by a certificate, which certificate will be held in such form and manner as determined by the Board. The terms and conditions of Restricted Stock Award Agreements may
change from time to time, and the terms and conditions of separate Restricted Stock Award Agreements need not be identical. Each Restricted Stock Award Agreement will conform to (through incorporation of the provisions hereof by reference in the
agreement or otherwise) the substance of each of the following provisions: 
 (i) Consideration. A Restricted Stock
Award may be awarded in consideration for (A) cash, check, bank draft or money order payable to the Company, (B) past or future services to the Company or an Affiliate, or (C) any other form of legal consideration that may be
acceptable to the Board, in its sole discretion, and permissible under applicable law. 
 (ii) Vesting. Shares of
Common Stock awarded under the Restricted Stock Award Agreement may be subject to forfeiture to the Company in accordance with a vesting schedule to be determined by the Board. 

(iii) Termination of Participant’s Continuous Service. If a Participant’s Continuous Service terminates, the
Company may receive through a forfeiture condition or a repurchase right any or all of the shares of Common Stock held by the Participant that have not vested as of the date of termination of Continuous Service under the terms of the Restricted
Stock Award Agreement. 
 (iv) Transferability. Rights to acquire shares of Common Stock under the Restricted Stock
Award Agreement will be transferable by the Participant only upon such terms and conditions as are set forth in the Restricted Stock Award Agreement, as the Board will determine in its sole discretion, so long as Common Stock awarded under the
Restricted Stock Award Agreement remains subject to the terms of the Restricted Stock Award Agreement. 
 (v) Dividends.
A Restricted Stock Award Agreement may provide that any dividends paid on Restricted Stock will be subject to the same vesting and forfeiture restrictions as apply to the shares subject to the Restricted Stock Award to which they relate. 

(b) Restricted Stock Unit Awards. Each Restricted Stock Unit Award Agreement will be in such form and will contain such
terms and conditions as the Board will deem appropriate. The terms and conditions of Restricted Stock Unit Award Agreements may change from time to time, and the terms and conditions of separate Restricted Stock Unit Award Agreements need not be
identical. Each Restricted Stock Unit Award Agreement will conform 

  
 11. 








 
to (through incorporation of the provisions hereof by reference in the Agreement or otherwise) the substance of each of the following provisions: 

(i) Consideration. At the time of grant of a Restricted Stock Unit Award, the Board will determine the consideration,
if any, to be paid by the Participant upon delivery of each share of Common Stock subject to the Restricted Stock Unit Award. The consideration to be paid (if any) by the Participant for each share of Common Stock subject to a Restricted Stock Unit
Award may be paid in any form of legal consideration that may be acceptable to the Board, in its sole discretion, and permissible under applicable law. 

(ii) Vesting. At the time of the grant of a Restricted Stock Unit Award, the Board may impose such restrictions on or
conditions to the vesting of the Restricted Stock Unit Award as it, in its sole discretion, deems appropriate. 
 (iii)
Payment. A Restricted Stock Unit Award may be settled by the delivery of shares of Common Stock, their cash equivalent, any combination thereof or in any other form of consideration, as determined by the Board and contained in the Restricted
Stock Unit Award Agreement. 
 (iv) Additional Restrictions. At the time of the grant of a Restricted Stock Unit
Award, the Board, as it deems appropriate, may impose such restrictions or conditions that delay the delivery of the shares of Common Stock (or their cash equivalent) subject to a Restricted Stock Unit Award to a time after the vesting of such
Restricted Stock Unit Award. 
 (v) Dividend Equivalents. Dividend equivalents may be credited in respect of shares
of Common Stock covered by a Restricted Stock Unit Award, as determined by the Board and contained in the Restricted Stock Unit Award Agreement. At the sole discretion of the Board, such dividend equivalents may be converted into additional shares
of Common Stock covered by the Restricted Stock Unit Award in such manner as determined by the Board. Any additional shares covered by the Restricted Stock Unit Award credited by reason of such dividend equivalents will be subject to all of the same
terms and conditions of the underlying Restricted Stock Unit Award Agreement to which they relate. 
 (vi) Termination of
Participant’s Continuous Service. Except as otherwise provided in the applicable Restricted Stock Unit Award Agreement, such portion of the Restricted Stock Unit Award that has not vested will be forfeited upon the Participant’s
termination of Continuous Service. 
 (c) Performance Awards. 

(i) Performance Stock Awards. A Performance Stock Award is a Stock Award (covering a number of shares not in excess of
that set forth in Section 3(d) above) that is payable (including that may be granted, may vest or may be exercised) contingent upon the attainment during a Performance Period of certain Performance Goals. A Performance Stock Award may, but need
not, require the Participant’s completion of a specified period of Continuous Service. The length of any Performance Period, the Performance Goals to be achieved during the Performance Period, and the measure of whether and to what degree such
Performance Goals have been attained will be conclusively determined by the Committee (or, if 

  
 12. 








 
not required for compliance with Section 162(m) of the Code, the Board), in its sole discretion. In addition, to the extent permitted by applicable law and the applicable Award Agreement,
the Board may determine that cash may be used in payment of Performance Stock Awards. 
 (ii) Performance Cash
Awards. A Performance Cash Award is a cash award (for a dollar value not in excess of that set forth in Section 3(d) above) that is payable contingent upon the attainment during a Performance Period of certain Performance Goals. A
Performance Cash Award may also require the completion of a specified period of Continuous Service. At the time of grant of a Performance Cash Award, the length of any Performance Period, the Performance Goals to be achieved during the Performance
Period, and the measure of whether and to what degree such Performance Goals have been attained will be conclusively determined by the Committee (or, if not required for compliance with Section 162(m) of the Code, the Board), in its sole
discretion. The Board may specify the form of payment of Performance Cash Awards, which may be cash or other property, or may provide for a Participant to have the option for his or her Performance Cash Award, or such portion thereof as the Board
may specify, to be paid in whole or in part in cash or other property. 
 (iii) Board Discretion. The Board retains
the discretion to reduce or eliminate the compensation or economic benefit due upon attainment of Performance Goals and to define the manner of calculating the Performance Criteria it selects to use for a Performance Period. Partial achievement of
the specified criteria may result in the payment or vesting corresponding to the degree of achievement as specified in the Stock Award Agreement or the written terms of a Performance Cash Award. 

(iv) Section 162(m) Compliance. Unless otherwise permitted in compliance with the requirements of
Section 162(m) of the Code with respect to an Award intended to qualify as “performance-based compensation” thereunder, the Committee will establish the Performance Goals applicable to, and the formula for calculating the amount
payable under, the Award no later than the earlier of (a) the date 90 days after the commencement of the applicable Performance Period, and (b) the date on which 25% of the Performance Period has elapsed, and in any event at a time when
the achievement of the applicable Performance Goals remains substantially uncertain. Prior to the payment of any compensation under an Award intended to qualify as “performance-based compensation” under Section 162(m) of the Code, the
Committee will certify the extent to which any Performance Goals and any other material terms under such Award have been satisfied (other than in cases where such Performance Goals relate solely to the increase in the value of the Common Stock).
Notwithstanding satisfaction of, or completion of any Performance Goals, the number of shares of Common Stock, Options, cash or other benefits granted, issued, retainable and/or vested under an Award on account of satisfaction of such Performance
Goals may be reduced by the Committee on the basis of such further considerations as the Committee, in its sole discretion, will determine. 

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


  
 13. 








 
to determine the persons to whom and the time or times at which such Other Stock Awards will be granted, the number of shares of Common Stock (or the cash equivalent thereof) to be granted
pursuant to such Other Stock Awards and all other terms and conditions of such Other Stock Awards. 
 7. COVENANTS
OF THE COMPANY. 
 (a) Availability of Shares. The Company will keep
available at all times the number of shares of Common Stock reasonably required to satisfy then-outstanding Awards. 

(b) Securities Law Compliance. The Company will seek to obtain from each regulatory commission or agency having
jurisdiction over the Plan such authority as may be required to grant Stock Awards and to issue and sell shares of Common Stock upon exercise of the Stock Awards; provided, however, that this undertaking will not require the Company to
register under the Securities Act the Plan, any Stock Award or any Common Stock issued or issuable pursuant to any such Stock Award. If, after reasonable efforts and at a reasonable cost, the Company is unable to obtain from any such regulatory
commission or agency the authority that counsel for the Company deems necessary for the lawful issuance and sale of Common Stock under the Plan, the Company will be relieved from any liability for failure to issue and sell Common Stock upon exercise
of such Stock Awards unless and until such authority is obtained. A Participant will not be eligible for the grant of an Award or the subsequent issuance of cash or Common Stock pursuant to the Award if such grant or issuance would be in violation
of any applicable securities law. 
 (c) No Obligation to Notify or Minimize Taxes. The Company will have no duty or
obligation to any Participant to advise such holder as to the time or manner of exercising such Stock Award. Furthermore, the Company will have no duty or obligation to warn or otherwise advise such holder of a pending termination or expiration of
an Award or a possible period in which the Award may not be exercised. The Company has no duty or obligation to minimize the tax consequences of an Award to the holder of such Award. 

8. MISCELLANEOUS. 

(a) Use of Proceeds from Sales of Common Stock. Proceeds from the sale of shares of Common Stock pursuant to Awards will
constitute general funds of the Company. 
 (b) Corporate Action Constituting Grant of Awards. Corporate action
constituting a grant by the Company of an Award to any Participant will be deemed completed as of the date of such corporate action, unless otherwise determined by the Board, regardless of when the instrument, certificate, or letter evidencing the
Award is communicated to, or actually received or accepted by, the Participant. In the event that the corporate records (e.g., Board consents, resolutions or minutes) documenting the corporate action constituting the grant contain terms (e.g.,
exercise price, vesting schedule or number of shares) that are inconsistent with those in the Award Agreement or related grant documents as a result of a clerical error in the papering of the Award Agreement or related grant documents, the corporate
records will control and the Participant will have no legally binding right to the incorrect term in the Award Agreement or related grant documents. 

  
 14. 








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

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

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

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

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

  
 15. 








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

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

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

(k) Compliance with Section 409A of the Code. Unless otherwise expressly provided for in an Award Agreement, the
Plan and Award Agreements will be interpreted to the greatest extent possible in a manner that makes the Plan and the Awards granted hereunder exempt from Section 409A of the Code, and, to the extent not so exempt, in compliance with
Section 409A of the Code. If the Board determines that any Award granted hereunder is not exempt from and is therefore subject to Section 409A of the Code, the Award Agreement 

  
 16. 








 
evidencing such Award will incorporate the terms and conditions necessary to avoid the consequences specified in Section 409A(a)(1) of the Code, and to the extent an Award Agreement is
silent on terms necessary for compliance, such terms are hereby incorporated by reference into the Award Agreement. Notwithstanding anything to the contrary in this Plan (and unless the Award Agreement specifically provides otherwise), if the shares
of Common Stock are publicly traded, and if a Participant holding an Award that constitutes “deferred compensation” under Section 409A of the Code is a “specified employee” for purposes of Section 409A of the Code, no
distribution or payment of any amount that is due because of a “separation from service” (as defined in Section 409A of the Code without regard to alternative definitions thereunder) will be issued or paid before the date that is six
months following the date of such Participant’s “separation from service” (as defined in Section 409A of the Code without regard to alternative definitions thereunder) or, if earlier, the date of the Participant’s death,
unless such distribution or payment can be made in a manner that complies with Section 409A of the Code, and any amounts so deferred will be paid in a lump sum on the day after such six month period elapses, with the balance paid thereafter on
the original schedule. 
 (l) Clawback/Recovery. All Awards granted under the Plan will be subject to recoupment in
accordance with any clawback policy that the Company is required to adopt pursuant to the listing standards of any national securities exchange or association on which the Company’s securities are listed or as is otherwise required by the
Dodd-Frank Wall Street Reform and Consumer Protection Act or other applicable law. In addition, the Board may impose such other clawback, recovery or recoupment provisions in an Award Agreement as the Board determines necessary or appropriate,
including but not limited to a reacquisition right in respect of previously acquired shares of Common Stock or other cash or property upon the occurrence of an event constituting Cause. No recovery of compensation under such a clawback policy will
be an event giving rise to a right to resign for “good reason” or “constructive termination” (or similar term) under any agreement with the Company. 

9. ADJUSTMENTS UPON CHANGES IN COMMON STOCK;
OTHER CORPORATE EVENTS. 
 (a) Capitalization Adjustments. In the
event of a Capitalization Adjustment, the Board will appropriately and proportionately adjust: (i) the class(es) and maximum number of securities subject to the Plan pursuant to Section 3(a), (ii) the class(es) and maximum number of
securities by which the share reserve is to increase automatically each year pursuant to Section 3(a), (iii) the class(es) and maximum number of securities that may be issued pursuant to the exercise of Incentive Stock Options pursuant to
Section 3(c), (iv) the class(es) and maximum number of securities that may be awarded to any person pursuant to Sections 3(d), and (v) the class(es) and number of securities and price per share of stock subject to outstanding Stock
Awards. The Board will make such adjustments, and its determination will be final, binding and conclusive. 
 (b)
Dissolution. Except as otherwise provided in the Stock Award Agreement, in the event of a Dissolution of the Company, all outstanding Stock Awards (other than Stock Awards consisting of vested and outstanding shares of Common Stock not subject
to a forfeiture condition or the Company’s right of repurchase) will terminate immediately prior to the completion of such Dissolution, and the shares of Common Stock subject to the Company’s repurchase rights or subject to a forfeiture
condition may be repurchased or reacquired by the 

  
 17. 








 
Company notwithstanding the fact that the holder of such Stock Award is providing Continuous Service; provided, however, that the Board may, in its sole discretion, cause some or all Stock
Awards to become fully vested, exercisable and/or no longer subject to repurchase or forfeiture (to the extent such Stock Awards have not previously expired or terminated) before the Dissolution is completed but contingent on its completion. 

(c) Transaction. The following provisions shall apply to Stock Awards in the event of a Transaction unless otherwise
provided in the instrument evidencing the Stock Award or any other written agreement between the Company or any Affiliate and the Participant or unless otherwise expressly provided by the Board at the time of grant of a Stock Award. In the event of
a Transaction, then, notwithstanding any other provision of the Plan, the Board shall take one or more of the following actions with respect to Stock Awards, contingent upon the closing or completion of the Transaction: 

(i) arrange for the surviving corporation or acquiring corporation (or the surviving or acquiring corporation’s
parent company) to assume or continue the Stock Award or to substitute a similar stock award for the Stock Award (including, but not limited to, an award to acquire the same consideration paid to the stockholders of the Company pursuant to the
Transaction); 
 (ii) arrange for the assignment of any reacquisition or repurchase rights held by the Company in
respect of Common Stock issued pursuant to the Stock Award to the surviving corporation or acquiring corporation (or the surviving or acquiring corporation’s parent company); 

(iii) accelerate the vesting, in whole or in part, of the Stock Award (and, if applicable, the time at which the Stock
Award may be exercised) to a date prior to the effective time of such Transaction as the Board shall determine (or, if the Board shall not determine such a date, to the date that is five days prior to the effective date of the Transaction), with
such Stock Award terminating if not exercised (if applicable) at or prior to the effective time of the Transaction; 

(iv) arrange for the lapse, in whole or in part, of any reacquisition or repurchase rights held by the Company with
respect to the Stock Award; 
 (v) cancel or arrange for the cancellation of the Stock Award, to the extent not
vested or not exercised prior to the effective time of the Transaction, in exchange for such cash consideration, if any, as the Board, in its sole discretion, may consider appropriate; and 

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

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

(d) Change in Control. A Stock Award may be subject to additional acceleration of vesting and exercisability upon or
after a Change in Control as may be provided in the Stock Award Agreement for such Stock Award or as may be provided in any other written agreement between the Company or any Affiliate and the Participant, but in the absence of such provision, no
such acceleration will occur. 
 10. PLAN TERM; EARLIER TERMINATION
OR SUSPENSION OF THE PLAN. 
 The Board may
suspend or terminate the Plan at any time. No Incentive Stock Options may be granted after the tenth anniversary of the earlier of (i) the date the Plan is adopted by the Board (the “Adoption Date”), or (ii) the
date the Plan is approved by the stockholders of the Company. No Awards may be granted under the Plan while the Plan is suspended or after it is terminated. Suspension or termination of the Plan will not impair rights and obligations under any Award
granted while the Plan is in effect except with the written consent of the affected Participant or as otherwise permitted in the Plan. 

11. EXISTENCE OF THE PLAN; TIMING OF
FIRST GRANT OR EXERCISE. 
 The Plan will come into existence
on the Adoption Date; provided, however, that no Stock Award may be granted prior to the IPO Date. In addition, no Stock Award will be exercised (or, in the case of a Restricted Stock Award, Restricted Stock Unit Award, Performance Stock
Award, or Other Stock Award, no Stock Award will be granted) and no Performance Cash Award will be settled unless and until the Plan has been approved by the stockholders of the Company, which approval will be within 12 months after the date the
Plan is adopted by the Board. 
 12. CHOICE OF LAW. 

The law of the State of California will govern all questions concerning the construction, validity and interpretation of this
Plan, without regard to that state’s conflict of laws rules. 
 13. DEFINITIONS. As used in the Plan, the
following definitions will apply to the capitalized terms indicated below: 
 (a) “Affiliate”
means, at the time of determination, any “parent” or “subsidiary” of the Company as such terms are defined in Rule 405 of the Securities Act. The Board will have the authority to determine the time or times at which
“parent” or “subsidiary” status is determined within the foregoing definition. 
 (b)
“Award” means a Stock Award or a Performance Cash Award. 
 (c) “Award
Agreement” means a written agreement between the Company and a Participant evidencing the terms and conditions of an Award. 

  
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 (d) “Board” means the Board of Directors of the
Company. 
 (e) “Capital Stock” means each and every class of common stock of the Company,
regardless of the number of votes per share. 
 (f) “Capitalization Adjustment” means any
change that is made in, or other events that occur with respect to, the Common Stock subject to the Plan or subject to any Stock Award after the Adoption Date without the receipt of consideration by the Company through merger, consolidation,
reorganization, recapitalization, reincorporation, stock dividend, dividend in property other than cash, large nonrecurring cash dividend, stock split, reverse stock split, liquidating dividend, combination of shares, exchange of shares, change in
corporate structure or any similar equity restructuring transaction, as that term is used in Statement of Financial Accounting Standards Board Accounting Standards Codification Topic 718 (or any successor thereto). Notwithstanding the foregoing, the
conversion of any convertible securities of the Company will not be treated as a Capitalization Adjustment. 
 (g)
“Cause” shall have the meaning ascribed to such term in any written agreement between the Participant and the Company defining such term and, in the absence of such agreement, such term means, with respect to a
Participant, the occurrence of any of the following events: (i) such Participant’s commission of any felony or any crime involving fraud, dishonesty or moral turpitude under the laws of the United States or any state thereof;
(ii) such Participant’s attempted commission of, or participation in, a fraud or act of dishonesty against the Company; (iii) such Participant’s intentional, material violation of any contract or agreement between the Participant
and the Company or of any statutory duty owed to the Company; (iv) such Participant’s unauthorized use or disclosure of the Company’s confidential information or trade secrets; or (v) such Participant’s gross misconduct. The
determination that a termination of the Participant’s Continuous Service is either for Cause or without Cause shall be made by the Company, in its sole discretion. Any determination by the Company that the Continuous Service of a Participant
was terminated with or without Cause for the purposes of outstanding Awards held by such Participant shall have no effect upon any determination of the rights or obligations of the Company or such Participant for any other purpose. 

(h) “Change in Control” means the occurrence, in a single transaction or in a series of related
transactions, of any one or more of the following events: 
 (i) any Exchange Act Person becomes the Owner, directly
or indirectly, of securities of the Company representing more than 50% of the combined voting power of the Company’s then outstanding securities other than by virtue of a merger, consolidation or similar transaction. Notwithstanding the
foregoing, a Change in Control will not be deemed to occur (A) on account of the acquisition of securities of the Company directly from the Company, (B) on account of the acquisition of securities of the Company by an investor, any
affiliate thereof or any other Exchange Act Person that acquires the Company’s securities in a transaction or series of related transactions the primary purpose of which is to obtain financing for the Company through the issuance of equity
securities, (C) on account of the acquisition of securities of the Company by any individual who is, on the IPO Date, either an executive officer or a Director (either, an “IPO Investor”) and/or any entity in which an
IPO Investor has a direct or indirect interest (whether in the form of voting rights or participation in profits or capital 

  
 20. 








 
contributions) of more than 50% (collectively, the “IPO Entities”) or on account of the IPO Entities continuing to hold shares that come to represent more than 50% of the
combined voting power of the Company’s then outstanding securities as a result of the conversion of any class of the Company’s securities into another class of the Company’s securities having a different number of votes per share
pursuant to the conversion provisions set forth in the Company’s Amended and Restated Certificate of Incorporation; or (D) solely because the level of Ownership held by any Exchange Act Person (the “Subject Person”)
exceeds the designated percentage threshold of the outstanding voting securities as a result of a repurchase or other acquisition of voting securities by the Company reducing the number of shares outstanding, provided that if a Change in Control
would occur (but for the operation of this sentence) as a result of the acquisition of voting securities by the Company, and after such share acquisition, the Subject Person becomes the Owner of any additional voting securities that, assuming the
repurchase or other acquisition had not occurred, increases the percentage of the then outstanding voting securities Owned by the Subject Person over the designated percentage threshold, then a Change in Control will be deemed to occur; 

(ii) there is consummated a merger, consolidation or similar transaction involving (directly or indirectly) the Company
and, immediately after the consummation of such merger, consolidation or similar transaction, the stockholders of the Company immediately prior thereto do not Own, directly or indirectly, either (A) outstanding voting securities representing
more than 50% of the combined outstanding voting power of the surviving Entity in such merger, consolidation or similar transaction or (B) more than 50% of the combined outstanding voting power of the parent of the surviving Entity in such
merger, consolidation or similar transaction, in each case in substantially the same proportions as their Ownership of the outstanding voting securities of the Company immediately prior to such transaction; provided, however, that a merger,
consolidation or similar transaction will not constitute a Change in Control under this prong of the definition if the outstanding voting securities representing more than 50% of the combined voting power of the surviving Entity or its parent are
owned by the IPO Entities; 
 (iii) there is consummated a sale, lease, exclusive license or other disposition of all
or substantially all of the consolidated assets of the Company and its Subsidiaries, other than a sale, lease, license or other disposition of all or substantially all of the consolidated assets of the Company and its Subsidiaries to an Entity, more
than 50% of the combined voting power of the voting securities of which are Owned by stockholders of the Company in substantially the same proportions as their Ownership of the outstanding voting securities of the Company immediately prior to such
sale, lease, license or other disposition; provided, however, that a sale, lease, exclusive license or other disposition of all or substantially all of the consolidated assets of the Company and its Subsidiaries will not constitute a Change
in Control under this prong of the definition if the outstanding voting securities representing more than 50% of the combined voting power of the acquiring Entity or its parent are owned by the IPO Entities; 

(iv) the stockholders of the Company approve or the Board approves a plan of complete dissolution or liquidation of the
Company, or a complete dissolution or liquidation of the Company will otherwise occur, except for a liquidation into a parent corporation; or 

  
 21. 








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

Notwithstanding the foregoing definition or any other provision of the Plan, the term Change in Control will not include a
sale of assets, merger or other transaction effected exclusively for the purpose of changing the domicile of the Company and the definition of Change in Control (or any analogous term) in an individual written agreement between the Company or any
Affiliate and the Participant will supersede the foregoing definition with respect to Awards subject to such agreement; provided, however, that if no definition of Change in Control or any analogous term is set forth in such an individual
written agreement, the foregoing definition will apply. 
 (i) “Code” means the Internal
Revenue Code of 1986, as amended, including any applicable regulations and guidance thereunder. 
 (j)
“Committee” means a committee of one or more Directors to whom authority has been delegated by the Board in accordance with Section 2(c). 

(k) “Common Stock” means, as of the IPO Date, the common stock of the Company, having one vote
per share. 
 (l) “Company” means Tocagen Inc., a Delaware corporation. 

(m) “Consultant” means any person, including an advisor, who is (i) engaged by the Company
or an Affiliate to render consulting or advisory services and is compensated for such services, or (ii) serving as a member of the board of directors of an Affiliate and is compensated for such services. However, service solely as a Director,
or payment of a fee for such service, will not cause a Director to be considered a “Consultant” for purposes of the Plan. Notwithstanding the foregoing, a person is treated as a Consultant under this Plan only if a Form S-8 Registration
Statement under the Securities Act is available to register either the offer or the sale of the Company’s securities to such person. 

(n) “Continuous Service” means that the Participant’s service with the Company or an
Affiliate, whether as an Employee, Director or Consultant, is not interrupted or terminated. A change in the capacity in which the Participant renders service to the Company or an Affiliate as an Employee, Consultant or Director or a change in the
entity for which the Participant renders such service, provided that there is no interruption or termination of the Participant’s service with the Company or an Affiliate, will not terminate a Participant’s Continuous Service; provided,
however, that if the Entity for which a Participant is rendering services ceases to qualify as an Affiliate, as determined by the Board, in its sole discretion, such Participant’s Continuous Service will be considered to have terminated on
the date such Entity ceases to qualify as an Affiliate. To the extent permitted by law, the Board or the chief executive officer of the Company, in that party’s sole discretion, may determine whether Continuous Service will


  
 22. 








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

(o) “Corporate Transaction” means the consummation, in a single transaction or in a series of
related transactions, of any one or more of the following events: 
 (i) a sale or other disposition of all or
substantially all, as determined by the Board, in its sole discretion, of the consolidated assets of the Company and its Subsidiaries; 

(ii) a sale or other disposition of more than 50% of the outstanding securities of the Company; 

(iii) a merger, consolidation or similar transaction following which the Company is not the surviving corporation; or

 (iv) a merger, consolidation or similar transaction following which the Company is the surviving corporation but
the shares of Common Stock outstanding immediately preceding the merger, consolidation or similar transaction are converted or exchanged by virtue of the merger, consolidation or similar transaction into other property, whether in the form of
securities, cash or otherwise. 
 (p) “Covered Employee” will have the meaning provided in
Section 162(m)(3) of the Code. 
 (q) “Director” means a member of the Board. 

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

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

  
 23. 








 (u) “Entity” means a corporation, partnership,
limited liability company or other entity. 
 (v) “Exchange Act” means the Securities
Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder. 
 (w) “Exchange
Act Person” means any natural person, Entity or “group” (within the meaning of Section 13(d) or 14(d) of the Exchange Act), except that “Exchange Act Person” will not include (i) the Company or any
Subsidiary of the Company, (ii) any employee benefit plan of the Company or any Subsidiary of the Company or any trustee or other fiduciary holding securities under an employee benefit plan of the Company or any Subsidiary of the Company,
(iii) an underwriter temporarily holding securities pursuant to a registered public offering of such securities, (iv) an Entity Owned, directly or indirectly, by the stockholders of the Company in substantially the same proportions as
their Ownership of stock of the Company; or (v) any natural person, Entity or “group” (within the meaning of Section 13(d) or 14(d) of the Exchange Act) that, as of the IPO Date, is the Owner, directly or indirectly, of
securities of the Company representing more than 50% of the combined voting power of the Company’s then outstanding securities. 

(x) “Fair Market Value” means, as of any date, the value of the Common Stock determined as
follows: 
 (i) If the Common Stock is listed on any established stock exchange or traded on any established market,
the Fair Market Value of a share of Common Stock will be, unless otherwise determined by the Board, the closing sales price for such stock as quoted on such exchange or market (or the exchange or market with the greatest volume of trading in the
Common Stock) on the date of determination, as reported in a source the Board deems reliable. 
 (ii) Unless
otherwise provided by the Board, if there is no closing sales price for the Common Stock on the date of determination, then the Fair Market Value will be the closing selling price on the last preceding date for which such quotation exists. 

(iii) In the absence of such markets for the Common Stock, the Fair Market Value will be determined by the Board in
good faith and in a manner that complies with Sections 409A and 422 of the Code. 
 (y) “Incentive Stock
Option” means an option granted pursuant to Section 5 of the Plan that is intended to be, and qualifies as, an “incentive stock option” within the meaning of Section 422 of the Code. 

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

(aa) “Non-Employee Director” means a Director who either (i) is not a current employee or
officer of the Company or an Affiliate, does not receive compensation, either directly or indirectly, from the Company or an Affiliate for services rendered as a consultant or in any capacity other than as a Director (except for an amount as to
which disclosure would not 

  
 24. 








 
be required under Item 404(a) of Regulation S-K promulgated pursuant to the Securities Act (“Regulation S-K”)), does not possess an interest in any other transaction
for which disclosure would be required under Item 404(a) of Regulation S-K, and is not engaged in a business relationship for which disclosure would be required pursuant to Item 404(b) of Regulation S-K; or (ii) is otherwise
considered a “non-employee director” for purposes of Rule 16b-3. 
 (bb) “Nonstatutory Stock
Option” means any Option granted pursuant to Section 5 of the Plan that does not qualify as an Incentive Stock Option. 

(cc) “Officer” means a person who is an officer of the Company within the meaning of
Section 16 of the Exchange Act. 
 (dd) “Option” means an Incentive Stock Option or a
Nonstatutory Stock Option to purchase shares of Common Stock granted pursuant to the Plan. 
 (ee) “Option
Agreement” means a written agreement between the Company and an Optionholder evidencing the terms and conditions of an Option grant. Each Option Agreement will be subject to the terms and conditions of the Plan. 

(ff) “Optionholder” means a person to whom an Option is granted pursuant to the Plan or, if
applicable, such other person who holds an outstanding Option. 
 (gg) “Other Stock Award”
means an award based in whole or in part by reference to the Common Stock which is granted pursuant to the terms and conditions of Section 6(d). 

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

(ii) “Outside Director” means a Director who either (i) is not a current employee of the
Company or an “affiliated corporation” (within the meaning of Treasury Regulations promulgated under Section 162(m) of the Code), is not a former employee of the Company or an “affiliated corporation” who receives
compensation for prior services (other than benefits under a tax-qualified retirement plan) during the taxable year, has not been an officer of the Company or an “affiliated corporation,” and does not receive remuneration from the Company
or an “affiliated corporation,” either directly or indirectly, in any capacity other than as a Director, or (ii) is otherwise considered an “outside director” for purposes of Section 162(m) of the Code. 

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

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

  
 25. 








 (ll) “Performance Cash Award” means an award of
cash granted pursuant to the terms and conditions of Section 6(c)(ii). 
 (mm) “Performance
Criteria” means the one or more criteria that the Board will select for purposes of establishing the Performance Goals for a Performance Period. The Performance Criteria that will be used to establish such Performance Goals may be based
on any one of, or combination of, the following as determined by the Board: (i) earnings (including earnings per share and net earnings); (ii) earnings before interest, taxes and depreciation; (iii) earnings before interest, taxes,
depreciation and amortization; (iv) earnings before interest, taxes, depreciation, amortization and legal settlements; (v) earnings before interest, taxes, depreciation, amortization, legal settlements and other income (expense);
(vi) earnings before interest, taxes, depreciation, amortization, legal settlements, other income (expense) and stock-based compensation; (vii) earnings before interest, taxes, depreciation, amortization, legal settlements, other income
(expense), stock-based compensation and changes in deferred revenue; (viii) earnings before interest, taxes, depreciation, amortization, legal settlements, other income (expense), stock-based compensation, other non-cash expenses and changes in
deferred revenue; (ix) total stockholder return; (x) return on equity or average stockholder’s equity; (xi) return on assets, investment, or capital employed; (xii) stock price; (xiii) margin (including gross margin);
(xiv) income (before or after taxes); (xv) operating income; (xvi) operating income after taxes; (xvii) pre-tax profit; (xviii) operating cash flow; (xix) sales or revenue targets; (xx) increases in revenue or
product revenue; (xxi) expenses and cost reduction goals; (xxii) improvement in or attainment of working capital levels; (xxiii) economic value added (or an equivalent metric); (xxiv) market share; (xxv) cash flow;
(xxvi) cash flow per share; (xxvii) cash balance; (xxviii) cash burn; (xxix) cash collections; (xxx) share price performance; (xxxi) debt reduction; (xxxii) implementation or completion of projects or processes
(including, without limitation, discovery of a pre-clinical drug candidate, recommendation of a drug candidate to enter a clinical trial, clinical trial initiation, clinical trial enrollment and dates, clinical trial results, regulatory filing
submissions (such as IND, BLA and NDA), regulatory filing acceptances, regulatory or advisory committee interactions, regulatory approvals, and product supply); (xxxiii) stockholders’ equity; (xxxiv) capital expenditures;
(xxxv) financings; (xxxvi) operating profit or net operating profit; (xxxvii) workforce diversity; (xxxviii) growth of net income or operating income; (xxxix) employee retention; (xl) initiation of studies by specific
dates; (xli) budget management; (xlii) submission to, or approval by, a regulatory body (including, but not limited to the U.S. Food and Drug Administration) of an applicable filing or a product; (xliii) regulatory milestones;
(xliv) progress of internal research or development programs; (xlv) progress of partnered programs; (xlvi) partner satisfaction; (xlvii) timely completion of clinical trials; (xlviii) milestones related to research
development (including, but not limited to, preclinical and clinical studies), product development and manufacturing; (xlix) expansion of sales in additional geographies or markets; (l) research progress, including the development of
programs; (li) strategic partnerships or transactions (including in-licensing and out-licensing of intellectual property; (lii) filing of patent applications and granting of patents; and (liii) to the extent that an Award is not
intended to comply with Section 162(m) of the Code, other measures of performance selected by the Board. 
 (nn)
“Performance Goals” means, for a Performance Period, the one or more goals established by the Board for the Performance Period based upon the Performance Criteria. Performance Goals may be based on a Company-wide basis,
with respect to one or more business units, divisions, Affiliates, or business segments, and in either absolute terms or relative 

  
 26. 








 
to the performance of one or more comparable companies or the performance of one or more relevant indices. Unless specified otherwise by the Board (i) in the Award Agreement at the time the
Award is granted or (ii) in such other document setting forth the Performance Goals at the time the Performance Goals are established, the Board will appropriately make adjustments in the method of calculating the attainment of Performance
Goals for a Performance Period as follows: (1) to exclude restructuring and/or other nonrecurring charges; (2) to exclude exchange rate effects; (3) to exclude the effects of changes to generally accepted accounting principles;
(4) to exclude the effects of any statutory adjustments to corporate tax rates; (5) to exclude the effects of any “items of an unusual nature or of infrequency of occurrence or non-recurring items” as determined under generally
accepted accounting principles; (6) to exclude the dilutive effects of acquisitions or joint ventures; (7) to assume that any business divested by the Company achieved performance objectives at targeted levels during the balance of a
Performance Period following such divestiture; (8) to exclude the effect of any change in the outstanding shares of common stock of the Company by reason of any stock dividend or split, stock repurchase, reorganization, recapitalization,
merger, consolidation, spin-off, combination or exchange of shares or other similar corporate change, or any distributions to common stockholders other than regular cash dividends; (9) to exclude the effects of stock based compensation and the
award of bonuses under the Company’s bonus plans; (10) to exclude costs incurred in connection with potential acquisitions or divestitures that are required to be expensed under generally accepted accounting principles; (11) to
exclude the goodwill and intangible asset impairment charges that are required to be recorded under generally accepted accounting principles; (12) to exclude the effect of any other unusual, non-recurring gain or loss or other extraordinary
item; and (13) to exclude the effects of the timing of acceptance for review and/or approval of submissions to the U.S. Food and Drug Administration or any other regulatory body. In addition, the Board retains the discretion to reduce or
eliminate the compensation or economic benefit due upon attainment of Performance Goals and to define the manner of calculating the Performance Criteria it selects to use for such Performance Period. Partial achievement of the specified criteria may
result in the payment or vesting corresponding to the degree of achievement as specified in the Stock Award Agreement or the written terms of a Performance Cash Award. 

(oo) “Performance Period” means the period of time selected by the Board over which the
attainment of one or more Performance Goals will be measured for the purpose of determining a Participant’s right to and the payment of a Stock Award or a Performance Cash Award. Performance Periods may be of varying and overlapping duration,
at the sole discretion of the Board. 
 (pp) “Performance Stock Award” means a Stock Award
granted under the terms and conditions of Section 6(c)(i). 
 (qq) “Plan” means this
Tocagen Inc. 2017 Equity Incentive Plan. 
 (rr) “Restricted Stock Award” means an award of
shares of Common Stock which is granted pursuant to the terms and conditions of Section 6(a). 
 (ss)
“Restricted Stock Award Agreement” means a written agreement between the Company and a holder of a Restricted Stock Award evidencing the terms and conditions of a 

  
 27. 








 
Restricted Stock Award grant. Each Restricted Stock Award Agreement will be subject to the terms and conditions of the Plan. 

(tt) “Restricted Stock Unit Award” means a right to receive shares of Common Stock which is
granted pursuant to the terms and conditions of Section 6(b). 
 (uu) “Restricted Stock Unit Award
Agreement” means a written agreement between the Company and a holder of a Restricted Stock Unit Award evidencing the terms and conditions of a Restricted Stock Unit Award grant. Each Restricted Stock Unit Award Agreement will be
subject to the terms and conditions of the Plan. 
 (vv) “Rule 16b-3” means Rule 16b-3
promulgated under the Exchange Act or any successor to Rule 16b-3, as in effect from time to time. 
 (ww)
“Securities Act” means the Securities Act of 1933, as amended. 
 (xx) “Stock
Appreciation Right” or “SAR” means a right to receive the appreciation on Common Stock that is granted pursuant to the terms and conditions of Section 5. 

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

(zz) “Stock Award” means any right to receive Common Stock granted under the Plan, including an
Incentive Stock Option, a Nonstatutory Stock Option, a Restricted Stock Award, a Restricted Stock Unit Award, a Stock Appreciation Right, a Performance Stock Award or any Other Stock Award. 

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

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

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

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

  
 28. 








 Standard Form 

TOCAGEN INC. 

STOCK OPTION GRANT NOTICE 

(2017 EQUITY INCENTIVE PLAN) 

Tocagen Inc. (the “Company”), pursuant to its 2017 Equity Incentive Plan (the “Plan”), hereby
grants to Optionholder an option to purchase the number of shares of the Company’s Common Stock set forth below. This option is subject to all of the terms and conditions as set forth in this Stock Option Grant Notice, in the Option Agreement,
the Plan and the Notice of Exercise, all of which are attached hereto and incorporated herein in their entirety. Capitalized terms not explicitly defined herein but defined in the Plan or the Option Agreement will have the same definitions as in the
Plan or the Option Agreement. If there is any conflict between the terms in this Stock Option Grant Notice and the Plan, the terms of the Plan will control. 
  

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

  

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

					
	Exercise Schedule:	  	 ☒
	  	 Same as Vesting Schedule
	  	 ☐
	  	 Early Exercise Permitted

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

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

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

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

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

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


  
  

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



  
 1. 








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

 

									
	TOCAGEN INC.	 		 	OPTIONHOLDER:
				
	 By:
	 	  
	 		 	  

	Signature	 		 	Signature
					
	 Title:
	 	  
	 		 	 Date:
	 	  

					
	 Date:
	 	  
	 		 		 	

 ATTACHMENTS: Option Agreement, 2017 Equity Incentive Plan and Notice of Exercise 

  
 2 








 ATTACHMENT I 

TOCAGEN INC. 

2017 EQUITY INCENTIVE PLAN 

OPTION AGREEMENT 

(INCENTIVE STOCK OPTION OR NONSTATUTORY STOCK
OPTION) 
 Pursuant to your Stock Option Grant Notice (“Grant Notice”) and this
Option Agreement, Tocagen Inc.(the “Company”) has granted you an option under its 2017 Equity Incentive Plan (the “Plan”) to purchase the number of shares of the Company’s Common Stock indicated
in your Grant Notice at the exercise price indicated in your Grant Notice. The option is granted to you effective as of the date of grant set forth in the Grant Notice (the “Date of Grant”). If there is any conflict between
the terms in this Option Agreement and the Plan, the terms of the Plan will control. Capitalized terms not explicitly defined in this Option Agreement or in the Grant Notice but defined in the Plan will have the same definitions as in the Plan. 

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

1. VESTING. Subject to the provisions contained herein, your option will vest as provided in your Grant
Notice. Vesting will cease upon the termination of your Continuous Service. 
 2. NUMBER OF
SHARES AND EXERCISE PRICE. The number of shares of Common Stock subject to your option and your exercise price per share in your Grant Notice will be adjusted for Capitalization
Adjustments. 
 3. EXERCISE RESTRICTION FOR
NON-EXEMPT EMPLOYEES. If you are an Employee eligible for overtime compensation under the Fair Labor Standards Act of 1938, as amended (that is, a “Non-Exempt Employee”), and
except as otherwise provided in the Plan, you may not exercise your option until you have completed at least six (6) months of Continuous Service measured from the Date of Grant, even if you have already been an employee for more than six
(6) months. Consistent with the provisions of the Worker Economic Opportunity Act, you may exercise your option as to any vested portion prior to such six (6) month anniversary in the case of (i) your death or disability, (ii) a
Corporate Transaction in which your option is not assumed, continued or substituted, (iii) a Change in Control or (iv) your termination of Continuous Service on your “retirement” (as defined in the Company’s benefit plans).

 4. EXERCISE PRIOR TO VESTING (“EARLY
EXERCISE”). If permitted in your Grant Notice (i.e., the “Exercise Schedule” indicates “Early Exercise Permitted”) and subject to the provisions of your option, you may elect at any time that is
both (i) during the period of your Continuous Service and (ii) during the term of your option, to exercise all or part of your option, including the unvested portion of your option; provided, however, that: 

  
 1 








 (a) a partial exercise of your option will be deemed to cover first vested
shares of Common Stock and then the earliest vesting installment of unvested shares of Common Stock; 
 (b) any
shares of Common Stock so purchased from installments that have not vested as of the date of exercise will be subject to the purchase option in favor of the Company as described in the Company’s form of Early Exercise Stock Purchase Agreement;

 (c) you will enter into the Company’s form of Early Exercise Stock Purchase Agreement with a vesting schedule
that will result in the same vesting as if no early exercise had occurred; and 
 (d) if your option is an Incentive
Stock Option, then, to the extent that the aggregate Fair Market Value (determined at the Date of Grant) of the shares of Common Stock with respect to which your option plus all other Incentive Stock Options you hold are exercisable for the first
time by you during any calendar year (under all plans of the Company and its Affiliates) exceeds one hundred thousand dollars ($100,000), your option(s) or portions thereof that exceed such limit (according to the order in which they were granted)
will be treated as Nonstatutory Stock Options. 
 5. METHOD OF PAYMENT.
You must pay the full amount of the exercise price for the shares you wish to exercise. You may pay the exercise price in cash or by check, bank draft or money order payable to the Company or in any other manner permitted by your Grant
Notice, which may include one or more of the following: 
 (a) Provided that at the time of exercise the
Common Stock is publicly traded, pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board that, prior to the issuance of Common Stock, results in either the receipt of cash (or check) by the Company or the
receipt of irrevocable instructions to pay the aggregate exercise price to the Company from the sales proceeds. This manner of payment is also known as a “broker-assisted exercise”, “same day sale”, or “sell to cover”.

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

(c) If this option is a Nonstatutory Stock Option, subject to the consent of the Company at the time of exercise, by a
“net exercise” arrangement pursuant to which the Company will reduce the number of shares of Common Stock issued upon exercise of your option by the largest whole number of shares with a Fair Market Value that does not exceed the aggregate
exercise price. You must pay any remaining balance of the aggregate exercise price 

  
 2 








 
not satisfied by the “net exercise” in cash or other permitted form of payment. Shares of Common Stock will no longer be outstanding under your option and will not be exercisable
thereafter if those shares (i) are used to pay the exercise price pursuant to the “net exercise,” (ii) are delivered to you as a result of such exercise, and (iii) are withheld to satisfy your tax withholding obligations.

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

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

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

(a) immediately upon the termination of your Continuous Service for Cause; 

(b) three (3) months after the termination of your Continuous Service for any reason other than Cause, your
Disability or your death (except as otherwise provided in Section 8(d) below); provided, however, that if during any part of such three (3) month period your option is not exercisable solely because of the condition set forth in
Section 7 above, your option will not expire until the earlier of the Expiration Date or until it has been exercisable for an aggregate period of three (3) months after the termination of your Continuous Service; provided further,
if during any part of such three (3) month period, the sale of any Common Stock received upon exercise of your option would violate the Company’s insider trading policy, then your option will not expire until the earlier of the Expiration
Date or until it has been exercisable for an aggregate period of three (3) months after the termination of your Continuous Service during which the sale of the Common Stock received upon exercise of your option would not be in violation of the
Company’s insider trading policy. Notwithstanding the foregoing, if (i) you are a Non-Exempt Employee, (ii) your Continuous Service terminates within six (6) months after the Date of Grant, and (iii) you have vested in a
portion of your option at the time of your termination of Continuous Service, your option will not expire until the earlier of (x) the later of (A) the date that is seven (7) months after the Date of Grant, and (B) the date that
is three (3) months after the termination of your Continuous Service, and (y) the Expiration Date; 
 (c)
twelve (12) months after the termination of your Continuous Service due to your Disability (except as otherwise provided in Section 8(d)) below; 

  
 3 








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

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

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

If your option is an Incentive Stock Option, note that to obtain the federal income tax advantages associated with an
Incentive Stock Option, the Code requires that at all times beginning on the Date of Grant and ending on the day three (3) months before the date of your option’s exercise, you must be an employee of the Company or an Affiliate, except in
the event of your death or Disability. The Company has provided for extended exercisability of your option under certain circumstances for your benefit but cannot guarantee that your option will necessarily be treated as an Incentive Stock Option if
you continue to provide services to the Company or an Affiliate as a Consultant or Director after your employment terminates or if you otherwise exercise your option more than three (3) months after the date your employment with the Company or
an Affiliate terminates. 
 9. EXERCISE. 

(a) You may exercise the vested portion of your option (and the unvested portion of your option if your Grant Notice so
permits) during its term by (i) delivering a Notice of Exercise (in a form designated by the Company) or completing such other documents and/or procedures designated by the Company for exercise and (ii) paying the exercise price and any
applicable withholding taxes to the Company’s Secretary, stock plan administrator, or such other person as the Company may designate, together with such additional documents as the Company may then require. 

(b) By exercising your option you agree that, as a condition to any exercise of your option, the Company may require
you to enter into an arrangement providing for the payment by you to the Company of any tax withholding obligation of the Company arising by reason of (i) the exercise of your option, (ii) the lapse of any substantial risk of forfeiture to
which the shares of Common Stock are subject at the time of exercise, or (iii) the disposition of shares of Common Stock acquired upon such exercise. 

(c) If your option is an Incentive Stock Option, by exercising your option you agree that you will notify the Company
in writing within fifteen (15) days after the date of any disposition of any of the shares of the Common Stock issued upon exercise of your option that occurs within two (2) years after the Date of Grant or within one (1) year after
such shares of Common Stock are transferred upon exercise of your option. 
 (d) By accepting your option you agree
that you will not sell, dispose of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale, any shares of Common Stock or other securities of
the Company held by you, for a period of one hundred eighty (180) days following the effective date of a registration statement of the Company filed under the Securities Act or such longer period as the underwriters or the Company will request
to facilitate 

  
 4 








 
compliance with FINRA Rule 2711 or NYSE Member Rule 472 or any successor or similar rules or regulation (the “Lock-Up Period”); provided, however, that nothing
contained in this Section 9(d) will prevent the exercise of a repurchase option, if any, in favor of the Company during the Lock-Up Period. You further agree to execute and deliver such other agreements as may be reasonably requested by the
Company or the underwriters that are consistent with the foregoing or that are necessary to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to your shares of
Common Stock until the end of such period. You also agree that any transferee of any shares of Common Stock (or other securities) of the Company held by you will be bound by this Section 9(d). The underwriters of the Company’s stock are
intended third party beneficiaries of this Section 9(d) and will have the right, power and authority to enforce the provisions hereof as though they were a party hereto. 

10. TRANSFERABILITY. Except as otherwise provided in this Section 10, your option is not
transferable, except by will or by the laws of descent and distribution, and is exercisable during your life only by you. 

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

(c) Beneficiary Designation. Upon receiving written permission from the Board or its duly authorized designee, you may,
by delivering written notice to the Company, in a form approved by the Company and any broker designated by the Company to handle option exercises, designate a third party who, on your death, will thereafter be entitled to exercise this option and
receive the Common Stock or other consideration resulting from such exercise. In the absence of such a designation, your executor or administrator of your estate will be entitled to exercise this option and receive, on behalf of your estate, the
Common Stock or other consideration resulting from such exercise. 
 11. OPTION NOT
A SERVICE CONTRACT. Your option is not an employment or service contract, and nothing in your option will be deemed to create in any way whatsoever any obligation on your part to continue in the
employ of the Company or an Affiliate, or of the 

  
 5 








 
Company or an Affiliate to continue your employment. In addition, nothing in your option will obligate the Company or an Affiliate, their respective stockholders, boards of directors, officers or
employees to continue any relationship that you might have as a Director or Consultant for the Company or an Affiliate. 

12. WITHHOLDING OBLIGATIONS. 

(a) At the time you exercise your option, in whole or in part, and at any time thereafter as requested by the Company,
you hereby authorize withholding from payroll and any other amounts payable to you, and otherwise agree to make adequate provision for (including by means of a “same day sale” pursuant to a program developed under Regulation T as
promulgated by the Federal Reserve Board to the extent permitted by the Company), any sums required to satisfy the federal, state, local and foreign tax withholding obligations of the Company or an Affiliate, if any, which arise in connection with
the exercise of your option. 
 (b) If this option is a Nonstatutory Stock Option, then upon your request and subject
to approval by the Company, and compliance with any applicable legal conditions or restrictions, the Company may withhold from fully vested shares of Common Stock otherwise issuable to you upon the exercise of your option a number of whole shares of
Common Stock having a Fair Market Value, determined by the Company as of the date of exercise, not in excess of the minimum amount of tax required to be withheld by law (or such lower amount as may be necessary to avoid classification of your option
as a liability for financial accounting purposes). If the date of determination of any tax withholding obligation is deferred to a date later than the date of exercise of your option, share withholding pursuant to the preceding sentence shall not be
permitted unless you make a proper and timely election under Section 83(b) of the Code, covering the aggregate number of shares of Common Stock acquired upon such exercise with respect to which such determination is otherwise deferred, to
accelerate the determination of such tax withholding obligation to the date of exercise of your option. Notwithstanding the filing of such election, shares of Common Stock shall be withheld solely from fully vested shares of Common Stock determined
as of the date of exercise of your option that are otherwise issuable to you upon such exercise. Any adverse consequences to you arising in connection with such share withholding procedure shall be your sole responsibility. 

(c) You may not exercise your option unless the tax withholding obligations of the Company and/or any Affiliate are
satisfied. Accordingly, you may not be able to exercise your option when desired even though your option is vested, and the Company will have no obligation to issue a certificate for such shares of Common Stock or release such shares of Common Stock
from any escrow provided for herein, if applicable, unless such obligations are satisfied. 
 13. TAX
CONSEQUENCES. You hereby agree that the Company does not have a duty to design or administer the Plan or its other compensation programs in a manner that minimizes your tax liabilities. You will not make any claim
against the Company, or any of its Officers, Directors, Employees or Affiliates related to tax liabilities arising from your option or your other compensation. In particular, you acknowledge that this option is exempt from Section 409A of the
Code only if the exercise price per share specified in the Grant Notice is at least equal to the 

  
 6 








 
“fair market value” per share of the Common Stock on the Date of Grant and there is no other impermissible deferral of compensation associated with the option. 

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

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

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

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

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

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

  
 7 








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

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

(b) You agree upon request to execute any further documents or instruments necessary or desirable in the sole
determination of the Company to carry out the purposes or intent of your option. 
 (c) You acknowledge and agree
that you have reviewed your option in its entirety, have had an opportunity to obtain the advice of counsel prior to executing and accepting your option, and fully understand all provisions of your option. 

(d) This Option Agreement will be subject to all applicable laws, rules, and regulations, and to such approvals by any
governmental agencies or national securities exchanges as may be required. 
 (e) All obligations of the Company
under the Plan and this Option Agreement will be binding on any successor to the Company, whether the existence of such successor is the result of a direct or indirect purchase, merger, consolidation, or otherwise, of all or substantially all of the
business and/or assets of the Company. 
 *        *        *

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

  
 8 








 ATTACHMENT II 

2017 EQUITY INCENTIVE PLAN 

  
 1 








 ATTACHMENT III 

NOTICE OF EXERCISE 

 

			
	 Tocagen Inc.
	  	
	 [Address]
	  	
Date of Exercise:                   
  


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

									
	 Type of option (check one):
	  	 	Incentive 	☐ 	 	 	Nonstatutory 	☐ 
			
	 Stock option dated:
	  				 			
			
	 Number of Shares as to which option is exercised:
	  				 			
			
	 Certificates to be issued in name of:
	  				 			
			
	 Total exercise price:
	  	$	            	  	 	$	            	  
			
	 Cash payment delivered herewith:
	  	$	            	  	 	$	            	  
			
	 [Value of
                 Shares delivered herewith2:
	  	$	            	  	 	$	            	] 
			
	 [Value of
                 Shares pursuant to net exercise3:
	  	$	            	  	 	$	            	] 
			
	 [Regulation T Program (cashless
exercise4):
	  	$	            	  	 	$	            	] 

  
  

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




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



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



  
 1 








 By this exercise, I agree (i) to provide such additional documents as you
may require pursuant to the terms of the Tocagen Inc. 2017 Equity Incentive Plan, (ii) to provide for the payment by me to you (in the manner designated by you) of your withholding obligation, if any, relating to the exercise of this option,
and (iii) if this exercise relates to an incentive stock option, to notify you in writing within fifteen (15) days after the date of any disposition of any of the Shares issued upon exercise of this option that occurs within two
(2) years after the date of grant of this option or within one (1) year after such Shares are issued upon exercise of this option. 
  

	
	Very truly yours,
	
	  




  
 2 








 Double-Trigger Form 

TOCAGEN INC. 

STOCK OPTION GRANT NOTICE 

(2017 EQUITY INCENTIVE PLAN) 

Tocagen Inc. (the “Company”), pursuant to its 2017 Equity Incentive Plan (the “Plan”), hereby
grants to Optionholder an option to purchase the number of shares of the Company’s Common Stock set forth below. This option is subject to all of the terms and conditions as set forth in this Stock Option Grant Notice, in the Option Agreement,
the Plan and the Notice of Exercise, all of which are attached hereto and incorporated herein in their entirety. Capitalized terms not explicitly defined herein but defined in the Plan or the Option Agreement will have the same definitions as in the
Plan or the Option Agreement. If there is any conflict between the terms in this Stock Option Grant Notice and the Plan, the terms of the Plan will control. 
  

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

  

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

					
	Exercise Schedule:	  	 ☒
	  	 Same as Vesting Schedule
	  	 ☐
	  	 Early Exercise Permitted

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

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

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

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

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

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


  
  

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



  
 1. 








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

 

									
	TOCAGEN INC.	 		 	OPTIONHOLDER:
				
	 By:
	 	  
	 		 	  

		 	Signature	 		 		 	Signature
					
	 Title:
	 	  
	 		 	 Date:
	 	  

					
	 Date:
	 	  
	 		 		 	

 ATTACHMENTS: Option Agreement, 2017 Equity Incentive Plan and Notice of Exercise 

  
 2 








 ATTACHMENT I 

TOCAGEN INC. 

2017 EQUITY INCENTIVE PLAN 

OPTION AGREEMENT 

(INCENTIVE STOCK OPTION OR NONSTATUTORY STOCK
OPTION) 
 Pursuant to your Stock Option Grant Notice (“Grant Notice”) and this
Option Agreement, Tocagen Inc.(the “Company”) has granted you an option under its 2017 Equity Incentive Plan (the “Plan”) to purchase the number of shares of the Company’s Common Stock indicated
in your Grant Notice at the exercise price indicated in your Grant Notice. The option is granted to you effective as of the date of grant set forth in the Grant Notice (the “Date of Grant”). If there is any conflict between
the terms in this Option Agreement and the Plan, the terms of the Plan will control. Capitalized terms not explicitly defined in this Option Agreement or in the Grant Notice but defined in the Plan will have the same definitions as in the Plan. 

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

1. VESTING. Subject to the provisions contained herein, your option will vest as provided in your Grant
Notice. Vesting will cease upon the termination of your Continuous Service. “Double-Trigger” Vesting Acceleration Provision: If a Change in Control occurs and within one (1) month prior to, or within twelve
(12) months after, the effective time of such Change in Control, your Continuous Service terminates due to an involuntary termination (not including death or Disability) without Cause or due to your voluntary termination with Good Reason, then,
as of the date of termination of Continuous Service, the vesting and exercisability of your option will be accelerated in full. 

(a) “Good Reason” means that one or more of the following are undertaken by the Company (or
successor to the Company, if applicable) without your express written consent: (i) a material reduction in your annual base salary; provided, however, that Good Reason will not be deemed to have occurred in the event of a reduction in
your annual base salary that is pursuant to a salary reduction program affecting substantially all of the employees of the Company and that does not adversely affect you to a greater extent than other similarly situated employees; (ii) a
material reduction in your authority, duties or responsibilities; (iii) any failure by the Company to continue in effect any material benefit plan or program, including incentive plans or plans with respect to the receipt of securities of the
Company, in which you were participating immediately prior to the effective date of the Change in Control (hereinafter referred to as “Benefit Plans”), or the taking of any action by the Company that would adversely affect
your participation in or reduce your benefits under the Benefit Plans or deprive you of any fringe benefit that you enjoyed immediately prior to the effective date of the Change in Control; provided, however, that Good Reason will not be
deemed to have occurred if the Company provides for your participation in benefit plans and programs that, taken as a whole, are comparable to the Benefit Plans; (iv) a relocation of your principal place of employment with the Company (or
successor to the Company, if applicable) to a place that increases your one-way 

  
 1 








 
commute by more than fifty (50) miles as compared to your then-current principal place of employment immediately prior to such relocation, except for required travel by you on the
Company’s business to an extent substantially consistent with your business travel obligations prior to the effective date of the Change in Control; or (v) a material breach by the Company of any provision of the Plan or the Option
Agreement or any other material agreement between you and the Company concerning the terms and conditions of your employment or service with the Company. 

(b) If any payment or benefit you would receive from the Company or otherwise in connection with a Change in Control or
other similar transaction (a “280G Payment”) would (i) constitute a “parachute payment” within the meaning of Section 280G of the Code, and (ii) but for this sentence, be subject to the excise tax
imposed by Section 4999 of the Code (the “Excise Tax”), then any such 280G Payment (a “Payment”) shall be equal to the Reduced Amount. The “Reduced Amount” shall be either
(x) the largest portion of the Payment that would result in no portion of the Payment (after reduction) being subject to the Excise Tax or (y) the largest portion, up to and including the total, of the Payment, whichever amount (i.e., the
amount determined by clause (x) or by clause (y)), after taking into account all applicable federal, state and local employment taxes, income taxes, and the Excise Tax (all computed at the highest applicable marginal rate), results in your
receipt, on an after-tax basis, of the greater economic benefit notwithstanding that all or some portion of the Payment may be subject to the Excise Tax. If a reduction in a Payment is required pursuant to the preceding sentence and the Reduced
Amount is determined pursuant to clause (x) of the preceding sentence, the reduction shall occur in the manner (the “Reduction Method”) that results in the greatest economic benefit for you. If more than one method of
reduction will result in the same economic benefit, the items so reduced will be reduced pro rata (the “Pro Rata Reduction Method”). 

Notwithstanding the foregoing, if the Reduction Method or the Pro Rata Reduction Method would result in any portion of the
Payment being subject to taxes pursuant to Section 409A of the Code that would not otherwise be subject to taxes pursuant to Section 409A of the Code, then the Reduction Method and/or the Pro Rata Reduction Method, as the case may be,
shall be modified so as to avoid the imposition of taxes pursuant to Section 409A of the Code as follows: (A) as a first priority, the modification shall preserve to the greatest extent possible, the greatest economic benefit for you as
determined on an after-tax basis; (B) as a second priority, Payments that are contingent on future events (e.g., being terminated without cause), shall be reduced (or eliminated) before Payments that are not contingent on future events; and
(C) as a third priority, Payments that are “deferred compensation” within the meaning of Section 409A of the Code shall be reduced (or eliminated) before Payments that are not deferred compensation within the meaning of
Section 409A of the Code. 
 Unless you and the Company agree on an alternative accounting firm, the accounting firm
engaged by the Company for general tax compliance purposes as of the day prior to the effective date of the change of control transaction triggering the Payment shall perform the foregoing calculations. If the accounting firm so engaged by the
Company is serving as accountant or auditor for the individual, entity or group effecting the change of control transaction, the Company shall appoint a nationally recognized accounting firm to make the determinations required hereunder. The Company
shall bear all expenses with respect to the determinations by such accounting firm required to be made hereunder. The Company shall use 

  
 2 








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

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

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

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

4. EXERCISE PRIOR TO VESTING (“EARLY
EXERCISE”). If permitted in your Grant Notice (i.e., the “Exercise Schedule” indicates “Early Exercise Permitted”) and subject to the provisions of your option, you may elect at any time that is
both (i) during the period of your Continuous Service and (ii) during the term of your option, to exercise all or part of your option, including the unvested portion of your option; provided, however, that: 

(a) a partial exercise of your option will be deemed to cover first vested shares of Common Stock and then the earliest
vesting installment of unvested shares of Common Stock; 
 (b) any shares of Common Stock so purchased from
installments that have not vested as of the date of exercise will be subject to the purchase option in favor of the Company as described in the Company’s form of Early Exercise Stock Purchase Agreement; 

(c) you will enter into the Company’s form of Early Exercise Stock Purchase Agreement with a vesting schedule that
will result in the same vesting as if no early exercise had occurred; and 

  
 3 








 (d) if your option is an Incentive Stock Option, then, to the extent that
the aggregate Fair Market Value (determined at the Date of Grant) of the shares of Common Stock with respect to which your option plus all other Incentive Stock Options you hold are exercisable for the first time by you during any calendar year
(under all plans of the Company and its Affiliates) exceeds one hundred thousand dollars ($100,000), your option(s) or portions thereof that exceed such limit (according to the order in which they were granted) will be treated as Nonstatutory Stock
Options. 
 5. METHOD OF PAYMENT. You must pay the full amount of the
exercise price for the shares you wish to exercise. You may pay the exercise price in cash or by check, bank draft or money order payable to the Company or in any other manner permitted by your Grant Notice, which may include one or
more of the following: 
 (a) Provided that at the time of exercise the Common Stock is publicly traded, pursuant to
a program developed under Regulation T as promulgated by the Federal Reserve Board that, prior to the issuance of Common Stock, results in either the receipt of cash (or check) by the Company or the receipt of irrevocable instructions to pay the
aggregate exercise price to the Company from the sales proceeds. This manner of payment is also known as a “broker-assisted exercise”, “same day sale”, or “sell to cover”. 

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

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


  
 4 








 
issuance of the shares would be exempt from the registration requirements of the Securities Act. The exercise of your option also must comply with all other applicable laws and regulations
governing your option, and you may not exercise your option if the Company determines that such exercise would not be in material compliance with such laws and regulations (including any restrictions on exercise required for compliance with Treas.
Reg. 1.401(k)-1(d)(3), if applicable). 
 8. TERM. You may not exercise your option before the Date of
Grant or after the expiration of the option’s term. The term of your option expires, subject to the provisions of Section 5(h) of the Plan, upon the earliest of the following: 

(a) immediately upon the termination of your Continuous Service for Cause; 

(b) three (3) months after the termination of your Continuous Service for any reason other than Cause, your
Disability or your death (except as otherwise provided in Section 8(d) below); provided, however, that if during any part of such three (3) month period your option is not exercisable solely because of the condition set forth in
Section 7 above, your option will not expire until the earlier of the Expiration Date or until it has been exercisable for an aggregate period of three (3) months after the termination of your Continuous Service; provided further,
if during any part of such three (3) month period, the sale of any Common Stock received upon exercise of your option would violate the Company’s insider trading policy, then your option will not expire until the earlier of the Expiration
Date or until it has been exercisable for an aggregate period of three (3) months after the termination of your Continuous Service during which the sale of the Common Stock received upon exercise of your option would not be in violation of the
Company’s insider trading policy. Notwithstanding the foregoing, if (i) you are a Non-Exempt Employee, (ii) your Continuous Service terminates within six (6) months after the Date of Grant, and (iii) you have vested in a
portion of your option at the time of your termination of Continuous Service, your option will not expire until the earlier of (x) the later of (A) the date that is seven (7) months after the Date of Grant, and (B) the date that
is three (3) months after the termination of your Continuous Service, and (y) the Expiration Date; 
 (c)
twelve (12) months after the termination of your Continuous Service due to your Disability (except as otherwise provided in Section 8(d)) below; 

(d) eighteen (18) months after your death if you die either during your Continuous Service or within three
(3) months after your Continuous Service terminates for any reason other than Cause; 
 (e) the Expiration Date
indicated in your Grant Notice; or 
 (f) the day before the tenth (10th) anniversary of the Date of Grant. 

If your option is an Incentive Stock Option, note that to obtain the federal income tax advantages associated with an
Incentive Stock Option, the Code requires that at all times beginning on the Date of Grant and ending on the day three (3) months before the date of your option’s exercise, you must be an employee of the Company or an Affiliate, except in
the event of your death or Disability. The Company has provided for extended exercisability of your option under certain circumstances for your benefit but cannot guarantee that your option will necessarily be treated as an Incentive Stock Option if
you continue to provide services to the 

  
 5 








 
Company or an Affiliate as a Consultant or Director after your employment terminates or if you otherwise exercise your option more than three (3) months after the date your employment with
the Company or an Affiliate terminates. 
 9. EXERCISE. 

(a) You may exercise the vested portion of your option (and the unvested portion of your option if your Grant Notice so
permits) during its term by (i) delivering a Notice of Exercise (in a form designated by the Company) or completing such other documents and/or procedures designated by the Company for exercise and (ii) paying the exercise price and any
applicable withholding taxes to the Company’s Secretary, stock plan administrator, or such other person as the Company may designate, together with such additional documents as the Company may then require. 

(b) By exercising your option you agree that, as a condition to any exercise of your option, the Company may require
you to enter into an arrangement providing for the payment by you to the Company of any tax withholding obligation of the Company arising by reason of (i) the exercise of your option, (ii) the lapse of any substantial risk of forfeiture to
which the shares of Common Stock are subject at the time of exercise, or (iii) the disposition of shares of Common Stock acquired upon such exercise. 

(c) If your option is an Incentive Stock Option, by exercising your option you agree that you will notify the Company
in writing within fifteen (15) days after the date of any disposition of any of the shares of the Common Stock issued upon exercise of your option that occurs within two (2) years after the Date of Grant or within one (1) year after
such shares of Common Stock are transferred upon exercise of your option. 
 (d) By accepting your option you agree
that you will not sell, dispose of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale, any shares of Common Stock or other securities of
the Company held by you, for a period of one hundred eighty (180) days following the effective date of a registration statement of the Company filed under the Securities Act or such longer period as the underwriters or the Company will request
to facilitate compliance with FINRA Rule 2711 or NYSE Member Rule 472 or any successor or similar rules or regulation (the “Lock-Up Period”); provided, however, that nothing contained in this Section 9(d) will
prevent the exercise of a repurchase option, if any, in favor of the Company during the Lock-Up Period. You further agree to execute and deliver such other agreements as may be reasonably requested by the Company or the underwriters that are
consistent with the foregoing or that are necessary to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to your shares of Common Stock until the end of such
period. You also agree that any transferee of any shares of Common Stock (or other securities) of the Company held by you will be bound by this Section 9(d). The underwriters of the Company’s stock are intended third party beneficiaries of
this Section 9(d) and will have the right, power and authority to enforce the provisions hereof as though they were a party hereto. 

  
 6 








 10. TRANSFERABILITY. Except as otherwise provided in this
Section 10, your option is not transferable, except by will or by the laws of descent and distribution, and is exercisable during your life only by you. 

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

(c) Beneficiary Designation. Upon receiving written permission from the Board or its duly authorized designee, you may,
by delivering written notice to the Company, in a form approved by the Company and any broker designated by the Company to handle option exercises, designate a third party who, on your death, will thereafter be entitled to exercise this option and
receive the Common Stock or other consideration resulting from such exercise. In the absence of such a designation, your executor or administrator of your estate will be entitled to exercise this option and receive, on behalf of your estate, the
Common Stock or other consideration resulting from such exercise. 
 11. OPTION NOT
A SERVICE CONTRACT. Your option is not an employment or service contract, and nothing in your option will be deemed to create in any way whatsoever any obligation on your part to continue in the
employ of the Company or an Affiliate, or of the Company or an Affiliate to continue your employment. In addition, nothing in your option will obligate the Company or an Affiliate, their respective stockholders, boards of directors, officers or
employees to continue any relationship that you might have as a Director or Consultant for the Company or an Affiliate. 

12. WITHHOLDING OBLIGATIONS. 

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

  
 7 








 
satisfy the federal, state, local and foreign tax withholding obligations of the Company or an Affiliate, if any, which arise in connection with the exercise of your option. 

(b) If this option is a Nonstatutory Stock Option, then upon your request and subject to approval by the Company, and
compliance with any applicable legal conditions or restrictions, the Company may withhold from fully vested shares of Common Stock otherwise issuable to you upon the exercise of your option a number of whole shares of Common Stock having a Fair
Market Value, determined by the Company as of the date of exercise, not in excess of the minimum amount of tax required to be withheld by law (or such lower amount as may be necessary to avoid classification of your option as a liability for
financial accounting purposes). If the date of determination of any tax withholding obligation is deferred to a date later than the date of exercise of your option, share withholding pursuant to the preceding sentence shall not be permitted unless
you make a proper and timely election under Section 83(b) of the Code, covering the aggregate number of shares of Common Stock acquired upon such exercise with respect to which such determination is otherwise deferred, to accelerate the
determination of such tax withholding obligation to the date of exercise of your option. Notwithstanding the filing of such election, shares of Common Stock shall be withheld solely from fully vested shares of Common Stock determined as of the date
of exercise of your option that are otherwise issuable to you upon such exercise. Any adverse consequences to you arising in connection with such share withholding procedure shall be your sole responsibility. 

(c) You may not exercise your option unless the tax withholding obligations of the Company and/or any Affiliate are
satisfied. Accordingly, you may not be able to exercise your option when desired even though your option is vested, and the Company will have no obligation to issue a certificate for such shares of Common Stock or release such shares of Common Stock
from any escrow provided for herein, if applicable, unless such obligations are satisfied. 
 13. TAX
CONSEQUENCES. You hereby agree that the Company does not have a duty to design or administer the Plan or its other compensation programs in a manner that minimizes your tax liabilities. You will not make any claim
against the Company, or any of its Officers, Directors, Employees or Affiliates related to tax liabilities arising from your option or your other compensation. In particular, you acknowledge that this option is exempt from Section 409A of the
Code only if the exercise price per share specified in the Grant Notice is at least equal to the “fair market value” per share of the Common Stock on the Date of Grant and there is no other impermissible deferral of compensation associated
with the option. 
 14. NOTICES. Any notices provided for in your option or the Plan will be given in
writing (including electronically) and will be deemed effectively given upon receipt or, in the case of notices delivered by mail by the Company to you, five (5) days after deposit in the United States mail, postage prepaid, addressed to you at
the last address you provided to the Company. The Company may, in its sole discretion, decide to deliver any documents related to participation in the Plan and this option by electronic means or to request your consent to participate in the Plan by
electronic means. By accepting this option, you consent to receive such documents by electronic delivery and to participate in the Plan through an on-line or electronic system established and maintained by the Company or another third party
designated by the Company. 

  
 8 








 15. GOVERNING PLAN DOCUMENT.
Your option is subject to all the provisions of the Plan, the provisions of which are hereby made a part of your option, and is further subject to all interpretations, amendments, rules and regulations, which may from time to time be promulgated and
adopted pursuant to the Plan. If there is any conflict between the provisions of your option and those of the Plan, the provisions of the Plan will control. In addition, your option (and any compensation paid or shares issued under your option) is
subject to recoupment in accordance with The Dodd–Frank Wall Street Reform and Consumer Protection Act and any implementing regulations thereunder, any clawback policy adopted by the Company and any compensation recovery policy otherwise
required by applicable law. 
 16. OTHER DOCUMENTS. You hereby acknowledge receipt of
and the right to receive a document providing the information required by Rule 428(b)(1) promulgated under the Securities Act, which includes the Plan prospectus. In addition, you acknowledge receipt of the Company’s policy permitting certain
individuals to sell shares only during certain “window” periods and the Company’s insider trading policy, in effect from time to time. 

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

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

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

20. MISCELLANEOUS. 

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

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

  
 9 








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

(d) This Option Agreement will be subject to all applicable laws, rules, and regulations, and to such approvals by any
governmental agencies or national securities exchanges as may be required. 
 (e) All obligations of the Company
under the Plan and this Option Agreement will be binding on any successor to the Company, whether the existence of such successor is the result of a direct or indirect purchase, merger, consolidation, or otherwise, of all or substantially all of the
business and/or assets of the Company. 
 *        *        *

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

  
 10 








 ATTACHMENT II 

2017 EQUITY INCENTIVE PLAN 

  
 1 








 ATTACHMENT III 

NOTICE OF EXERCISE 

 

			
	Tocagen Inc.	  	
	 [Address]
	  	
Date of Exercise:                   
  


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

									
	 Type of option (check one):
	  	 	Incentive 	☐ 	 	 	Nonstatutory 	☐ 
			
	 Stock option dated:
	  				 			
			
	 Number of Shares as to which option is exercised:
	  				 			
			
	 Certificates to be issued in name of:
	  				 			
			
	 Total exercise price:
	  	$	            	  	 	$	            	  
			
	 Cash payment delivered herewith:
	  	$	            	  	 	$	            	  
			
	 [Value of                  Shares delivered
herewith2:
	  	$	            	  	 	$	            	] 
			
	 [Value of                  Shares pursuant
to net exercise3:
	  	$	            	  	 	$	            	] 
			
	 [Regulation T Program (cashless exercise4):
	  	$	            	  	 	$	            	] 

  

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




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



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



  
 1 








 By this exercise, I agree (i) to provide such additional documents as you
may require pursuant to the terms of the Tocagen Inc. 2017 Equity Incentive Plan, (ii) to provide for the payment by me to you (in the manner designated by you) of your withholding obligation, if any, relating to the exercise of this option,
and (iii) if this exercise relates to an incentive stock option, to notify you in writing within fifteen (15) days after the date of any disposition of any of the Shares issued upon exercise of this option that occurs within two
(2) years after the date of grant of this option or within one (1) year after such Shares are issued upon exercise of this option. 
  

	
	 Very truly yours,

	
	  




  
 2 








 Non-Employee Director 

TOCAGEN INC. 

STOCK OPTION GRANT NOTICE 

(2017 EQUITY INCENTIVE PLAN) 

Tocagen Inc. (the “Company”), pursuant to its 2017 Equity Incentive Plan (the “Plan”), hereby
grants to Optionholder an option to purchase the number of shares of the Company’s Common Stock set forth below. This option is subject to all of the terms and conditions as set forth in this Stock Option Grant Notice, in the Option Agreement,
the Plan and the Notice of Exercise, all of which are attached hereto and incorporated herein in their entirety. Capitalized terms not explicitly defined herein but defined in the Plan or the Option Agreement will have the same definitions as in the
Plan or the Option Agreement. If there is any conflict between the terms in this Stock Option Grant Notice and the Plan, the terms of the Plan will control. 
  

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

  

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

					
	Exercise Schedule:	  	 ☒
	  	 Same as Vesting Schedule
	  	 ☐
	  	 Early Exercise Permitted

		
	 Vesting Schedule:
	  	
[                      
          , subject to Optionholder’s Continuous Service as of each such date and the potential vesting acceleration described in Section 1 of the Option Agreement]

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

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

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

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

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


  

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



  
 1. 








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

 

									
	 TOCAGEN INC.
	 		 	 OPTIONHOLDER:

				
	 By:
	 	  
	 		 	  

		 	Signature	 		 		 	Signature
					
	 Title:
	 	  
	 		 	 Date:
	 	  

					
	 Date:
	 	  
	 		 		 	

 ATTACHMENTS: Option Agreement, 2017 Equity Incentive Plan and Notice of
Exercise 

  
 2 








 ATTACHMENT I 

TOCAGEN INC. 

2017 EQUITY INCENTIVE PLAN 

OPTION AGREEMENT 

(INCENTIVE STOCK OPTION OR NONSTATUTORY STOCK
OPTION) 
 Pursuant to your Stock Option Grant Notice (“Grant Notice”) and this
Option Agreement, Tocagen Inc.(the “Company”) has granted you an option under its 2017 Equity Incentive Plan (the “Plan”) to purchase the number of shares of the Company’s Common Stock indicated
in your Grant Notice at the exercise price indicated in your Grant Notice. The option is granted to you effective as of the date of grant set forth in the Grant Notice (the “Date of Grant”). If there is any conflict between
the terms in this Option Agreement and the Plan, the terms of the Plan will control. Capitalized terms not explicitly defined in this Option Agreement or in the Grant Notice but defined in the Plan will have the same definitions as in the Plan. 

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

1. VESTING.  

(a) Subject to the provisions contained herein, your option will vest as provided in your Grant Notice. Vesting will
cease upon the termination of your Continuous Service. If a Change in Control occurs and your Continuous Service has not terminated as of immediately prior to such Change in Control, the vesting and exercisability of your option will be accelerated
in full. 
 (b) If any payment or benefit you would receive from the Company or otherwise in connection with a Change
in Control or other similar transaction (a “280G Payment”) would (i) constitute a “parachute payment” within the meaning of Section 280G of the Code, and (ii) but for this sentence, be subject to the
excise tax imposed by Section 4999 of the Code (the “Excise Tax”), then any such 280G Payment (a “Payment”) shall be equal to the Reduced Amount. The “Reduced Amount” shall
be either (x) the largest portion of the Payment that would result in no portion of the Payment (after reduction) being subject to the Excise Tax or (y) the largest portion, up to and including the total, of the Payment, whichever amount
(i.e., the amount determined by clause (x) or by clause (y)), after taking into account all applicable federal, state and local employment taxes, income taxes, and the Excise Tax (all computed at the highest applicable marginal rate), results
in your receipt, on an after-tax basis, of the greater economic benefit notwithstanding that all or some portion of the Payment may be subject to the Excise Tax. If a reduction in a Payment is required pursuant to the preceding sentence and the
Reduced Amount is determined pursuant to clause (x) of the preceding sentence, the reduction shall occur in the manner (the “Reduction Method”) that results in the greatest economic benefit for you. If more than one
method of reduction will result in the same economic benefit, the items so reduced will be reduced pro rata (the “Pro Rata Reduction Method”). 

  
 1 








 Notwithstanding the foregoing, if the Reduction Method or the Pro Rata Reduction
Method would result in any portion of the Payment being subject to taxes pursuant to Section 409A of the Code that would not otherwise be subject to taxes pursuant to Section 409A of the Code, then the Reduction Method and/or the Pro Rata
Reduction Method, as the case may be, shall be modified so as to avoid the imposition of taxes pursuant to Section 409A of the Code as follows: (A) as a first priority, the modification shall preserve to the greatest extent possible, the
greatest economic benefit for you as determined on an after-tax basis; (B) as a second priority, Payments that are contingent on future events (e.g., being terminated without cause), shall be reduced (or eliminated) before Payments that are not
contingent on future events; and (C) as a third priority, Payments that are “deferred compensation” within the meaning of Section 409A of the Code shall be reduced (or eliminated) before Payments that are not deferred
compensation within the meaning of Section 409A of the Code. 
 Unless you and the Company agree on an alternative
accounting firm, the accounting firm engaged by the Company for general tax compliance purposes as of the day prior to the effective date of the change of control transaction triggering the Payment shall perform the foregoing calculations. If the
accounting firm so engaged by the Company is serving as accountant or auditor for the individual, entity or group effecting the change of control transaction, the Company shall appoint a nationally recognized accounting firm to make the
determinations required hereunder. The Company shall bear all expenses with respect to the determinations by such accounting firm required to be made hereunder. The Company shall use commercially reasonable efforts to cause the accounting firm
engaged to make the determinations hereunder to provide its calculations, together with detailed supporting documentation, to you and the Company within fifteen (15) calendar days after the date on which your right to a 280G Payment becomes
reasonably likely to occur (if requested at that time by you or the Company) or such other time as requested by you or the Company. 

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

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

3. EXERCISE RESTRICTION FOR NON-EXEMPT
EMPLOYEES. If you are an Employee eligible for overtime compensation under the Fair Labor Standards Act of 1938, as amended (that is, a “Non-Exempt Employee”), and except as otherwise provided in the Plan,
you may not exercise your option until you have completed at least six (6) months of Continuous Service measured from the Date of Grant, even if you have already been an employee for more than six (6) months. Consistent with the provisions
of the Worker Economic Opportunity Act, you may exercise your option as to any vested portion prior to such six (6) month anniversary in 

  
 2 








 
the case of (i) your death or disability, (ii) a Corporate Transaction in which your option is not assumed, continued or substituted, (iii) a Change in Control or (iv) your
termination of Continuous Service on your “retirement” (as defined in the Company’s benefit plans). 
 4.
EXERCISE PRIOR TO VESTING (“EARLY EXERCISE”). If permitted in your Grant Notice (i.e., the “Exercise Schedule” indicates
“Early Exercise Permitted”) and subject to the provisions of your option, you may elect at any time that is both (i) during the period of your Continuous Service and (ii) during the term of your option, to exercise all or part of
your option, including the unvested portion of your option; provided, however, that: 
 (a) a partial exercise
of your option will be deemed to cover first vested shares of Common Stock and then the earliest vesting installment of unvested shares of Common Stock; 

(b) any shares of Common Stock so purchased from installments that have not vested as of the date of exercise will be
subject to the purchase option in favor of the Company as described in the Company’s form of Early Exercise Stock Purchase Agreement; 

(c) you will enter into the Company’s form of Early Exercise Stock Purchase Agreement with a vesting schedule that
will result in the same vesting as if no early exercise had occurred; and 
 (d) if your option is an Incentive Stock
Option, then, to the extent that the aggregate Fair Market Value (determined at the Date of Grant) of the shares of Common Stock with respect to which your option plus all other Incentive Stock Options you hold are exercisable for the first time by
you during any calendar year (under all plans of the Company and its Affiliates) exceeds one hundred thousand dollars ($100,000), your option(s) or portions thereof that exceed such limit (according to the order in which they were granted) will be
treated as Nonstatutory Stock Options. 
 5. METHOD OF PAYMENT. You must
pay the full amount of the exercise price for the shares you wish to exercise. You may pay the exercise price in cash or by check, bank draft or money order payable to the Company or in any other manner permitted by your Grant Notice,
which may include one or more of the following: 
 (a) Provided that at the time of exercise the Common Stock is
publicly traded, pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board that, prior to the issuance of Common Stock, results in either the receipt of cash (or check) by the Company or the receipt of
irrevocable instructions to pay the aggregate exercise price to the Company from the sales proceeds. This manner of payment is also known as a “broker-assisted exercise”, “same day sale”, or “sell to cover”. 

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


  
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form approved by the Company. You may not exercise your option by delivery to the Company of Common Stock if doing so would violate the provisions of any law, regulation or agreement restricting
the redemption of the Company’s stock. 
 (c) If this option is a Nonstatutory Stock Option, subject to the
consent of the Company at the time of exercise, by a “net exercise” arrangement pursuant to which the Company will reduce the number of shares of Common Stock issued upon exercise of your option by the largest whole number of shares with a
Fair Market Value that does not exceed the aggregate exercise price. You must pay any remaining balance of the aggregate exercise price not satisfied by the “net exercise” in cash or other permitted form of payment. Shares of Common Stock
will no longer be outstanding under your option and will not be exercisable thereafter if those shares (i) are used to pay the exercise price pursuant to the “net exercise,” (ii) are delivered to you as a result of such exercise,
and (iii) are withheld to satisfy your tax withholding obligations. 
 6. WHOLE
SHARES. You may exercise your option only for whole shares of Common Stock. 
 7.
SECURITIES LAW COMPLIANCE. In no event may you exercise your option unless the shares of Common Stock issuable upon exercise are then registered under the Securities Act or, if not registered, the
Company has determined that your exercise and the issuance of the shares would be exempt from the registration requirements of the Securities Act. The exercise of your option also must comply with all other applicable laws and regulations governing
your option, and you may not exercise your option if the Company determines that such exercise would not be in material compliance with such laws and regulations (including any restrictions on exercise required for compliance with Treas. Reg.
1.401(k)-1(d)(3), if applicable). 
 8. TERM. You may not exercise your option before the Date of
Grant or after the expiration of the option’s term. The term of your option expires, subject to the provisions of Section 5(h) of the Plan, upon the earliest of the following: 

(a) immediately upon the termination of your Continuous Service for Cause; 

(b) twelve (12) months after the termination of your Continuous Service for any reason other than Cause, your
Disability or your death (except as otherwise provided in Section 8(d)); 
 (c) twelve (12) months after
the termination of your Continuous Service due to your Disability (except as otherwise provided in Section 8(d)) below; 

(d) eighteen (18) months after your death if you die either during your Continuous Service or within three
(3) months after your Continuous Service terminates for any reason other than Cause; 
 (e) the Expiration Date
indicated in your Grant Notice; or 
 (f) the day before the tenth (10th) anniversary of the Date of Grant. 


  
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 If your option is an Incentive Stock Option, note that to obtain the federal
income tax advantages associated with an Incentive Stock Option, the Code requires that at all times beginning on the Date of Grant and ending on the day three (3) months before the date of your option’s exercise, you must be an employee
of the Company or an Affiliate, except in the event of your death or Disability. The Company has provided for extended exercisability of your option under certain circumstances for your benefit but cannot guarantee that your option will necessarily
be treated as an Incentive Stock Option if you continue to provide services to the Company or an Affiliate as a Consultant or Director after your employment terminates or if you otherwise exercise your option more than three (3) months after
the date your employment with the Company or an Affiliate terminates. 
 9. EXERCISE. 

(a) You may exercise the vested portion of your option (and the unvested portion of your option if your Grant Notice so
permits) during its term by (i) delivering a Notice of Exercise (in a form designated by the Company) or completing such other documents and/or procedures designated by the Company for exercise and (ii) paying the exercise price and any
applicable withholding taxes to the Company’s Secretary, stock plan administrator, or such other person as the Company may designate, together with such additional documents as the Company may then require. 

(b) By exercising your option you agree that, as a condition to any exercise of your option, the Company may require
you to enter into an arrangement providing for the payment by you to the Company of any tax withholding obligation of the Company arising by reason of (i) the exercise of your option, (ii) the lapse of any substantial risk of forfeiture to
which the shares of Common Stock are subject at the time of exercise, or (iii) the disposition of shares of Common Stock acquired upon such exercise. 

(c) If your option is an Incentive Stock Option, by exercising your option you agree that you will notify the Company
in writing within fifteen (15) days after the date of any disposition of any of the shares of the Common Stock issued upon exercise of your option that occurs within two (2) years after the Date of Grant or within one (1) year after
such shares of Common Stock are transferred upon exercise of your option. 
 (d) By accepting your option you agree
that you will not sell, dispose of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale, any shares of Common Stock or other securities of
the Company held by you, for a period of one hundred eighty (180) days following the effective date of a registration statement of the Company filed under the Securities Act or such longer period as the underwriters or the Company will request
to facilitate compliance with FINRA Rule 2711 or NYSE Member Rule 472 or any successor or similar rules or regulation (the “Lock-Up Period”); provided, however, that nothing contained in this Section 9(d) will
prevent the exercise of a repurchase option, if any, in favor of the Company during the Lock-Up Period. You further agree to execute and deliver such other agreements as may be reasonably requested by the Company or the underwriters that are
consistent with the foregoing or that are necessary to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to your shares of


  
 5 








 
Common Stock until the end of such period. You also agree that any transferee of any shares of Common Stock (or other securities) of the Company held by you will be bound by this
Section 9(d). The underwriters of the Company’s stock are intended third party beneficiaries of this Section 9(d) and will have the right, power and authority to enforce the provisions hereof as though they were a party hereto. 

10. TRANSFERABILITY. Except as otherwise provided in this Section 10, your option is not
transferable, except by will or by the laws of descent and distribution, and is exercisable during your life only by you. 

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

(c) Beneficiary Designation. Upon receiving written permission from the Board or its duly authorized designee, you may,
by delivering written notice to the Company, in a form approved by the Company and any broker designated by the Company to handle option exercises, designate a third party who, on your death, will thereafter be entitled to exercise this option and
receive the Common Stock or other consideration resulting from such exercise. In the absence of such a designation, your executor or administrator of your estate will be entitled to exercise this option and receive, on behalf of your estate, the
Common Stock or other consideration resulting from such exercise. 
 11. OPTION NOT
A SERVICE CONTRACT. Your option is not an employment or service contract, and nothing in your option will be deemed to create in any way whatsoever any obligation on your part to continue in the
employ of the Company or an Affiliate, or of the Company or an Affiliate to continue your employment. In addition, nothing in your option will obligate the Company or an Affiliate, their respective stockholders, boards of directors, officers or
employees to continue any relationship that you might have as a Director or Consultant for the Company or an Affiliate. 

  
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 12. WITHHOLDING OBLIGATIONS. 

(a) At the time you exercise your option, in whole or in part, and at any time thereafter as requested by the Company,
you hereby authorize withholding from payroll and any other amounts payable to you, and otherwise agree to make adequate provision for (including by means of a “same day sale” pursuant to a program developed under Regulation T as
promulgated by the Federal Reserve Board to the extent permitted by the Company), any sums required to satisfy the federal, state, local and foreign tax withholding obligations of the Company or an Affiliate, if any, which arise in connection with
the exercise of your option. 
 (b) If this option is a Nonstatutory Stock Option, then upon your request and subject
to approval by the Company, and compliance with any applicable legal conditions or restrictions, the Company may withhold from fully vested shares of Common Stock otherwise issuable to you upon the exercise of your option a number of whole shares of
Common Stock having a Fair Market Value, determined by the Company as of the date of exercise, not in excess of the minimum amount of tax required to be withheld by law (or such lower amount as may be necessary to avoid classification of your option
as a liability for financial accounting purposes). If the date of determination of any tax withholding obligation is deferred to a date later than the date of exercise of your option, share withholding pursuant to the preceding sentence shall not be
permitted unless you make a proper and timely election under Section 83(b) of the Code, covering the aggregate number of shares of Common Stock acquired upon such exercise with respect to which such determination is otherwise deferred, to
accelerate the determination of such tax withholding obligation to the date of exercise of your option. Notwithstanding the filing of such election, shares of Common Stock shall be withheld solely from fully vested shares of Common Stock determined
as of the date of exercise of your option that are otherwise issuable to you upon such exercise. Any adverse consequences to you arising in connection with such share withholding procedure shall be your sole responsibility. 

(c) You may not exercise your option unless the tax withholding obligations of the Company and/or any Affiliate are
satisfied. Accordingly, you may not be able to exercise your option when desired even though your option is vested, and the Company will have no obligation to issue a certificate for such shares of Common Stock or release such shares of Common Stock
from any escrow provided for herein, if applicable, unless such obligations are satisfied. 
 13. TAX
CONSEQUENCES. You hereby agree that the Company does not have a duty to design or administer the Plan or its other compensation programs in a manner that minimizes your tax liabilities. You will not make any claim
against the Company, or any of its Officers, Directors, Employees or Affiliates related to tax liabilities arising from your option or your other compensation. In particular, you acknowledge that this option is exempt from Section 409A of the
Code only if the exercise price per share specified in the Grant Notice is at least equal to the “fair market value” per share of the Common Stock on the Date of Grant and there is no other impermissible deferral of compensation associated
with the option. 
 14. NOTICES. Any notices provided for in your option or the Plan will be given in
writing (including electronically) and will be deemed effectively given upon receipt or, in the case of notices delivered by mail by the Company to you, five (5) days after deposit in the 

  
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United States mail, postage prepaid, addressed to you at the last address you provided to the Company. The Company may, in its sole discretion, decide to deliver any documents related to
participation in the Plan and this option by electronic means or to request your consent to participate in the Plan by electronic means. By accepting this option, you consent to receive such documents by electronic delivery and to participate in the
Plan through an on-line or electronic system established and maintained by the Company or another third party designated by the Company. 

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

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

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

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

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

  
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 20. MISCELLANEOUS. 

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

(b) You agree upon request to execute any further documents or instruments necessary or desirable in the sole
determination of the Company to carry out the purposes or intent of your option. 
 (c) You acknowledge and agree
that you have reviewed your option in its entirety, have had an opportunity to obtain the advice of counsel prior to executing and accepting your option, and fully understand all provisions of your option. 

(d) This Option Agreement will be subject to all applicable laws, rules, and regulations, and to such approvals by any
governmental agencies or national securities exchanges as may be required. 
 (e) All obligations of the Company
under the Plan and this Option Agreement will be binding on any successor to the Company, whether the existence of such successor is the result of a direct or indirect purchase, merger, consolidation, or otherwise, of all or substantially all of the
business and/or assets of the Company. 
 *        *        *

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

  
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 ATTACHMENT II 

2017 EQUITY INCENTIVE PLAN 

  
 1 








 ATTACHMENT III 

NOTICE OF EXERCISE 

 

					
	 Tocagen Inc.
	  			
	[Address]	  	 	Date of Exercise:                     	  

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

 

									
	 Type of option (check one):
	  	 	Incentive 	☐ 	 	 	Nonstatutory 	☒ 
			
	 Stock option dated:
	  				 			
			
	 Number of Shares as to which option is exercised:
	  				 			
			
	 Certificates to be issued in name of:
	  				 			
			
	 Total exercise price:
	  	$	        	  	 	$	            	  
			
	 Cash payment delivered herewith:
	  	$	            	  	 	$	            	  
			
	 [Value of                  Shares delivered
herewith2:
	  	$	            	  	 	$	            	] 
			
	 [Value of                  Shares pursuant
to net exercise3:
	  	$	            	  	 	$	            	] 
			
	 [Regulation T Program (cashless exercise4):
	  	$	            	  	 	$	            	] 

  
  

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




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



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



  
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 By this exercise, I agree (i) to provide such additional documents as you
may require pursuant to the terms of the Tocagen Inc. 2017 Equity Incentive Plan, (ii) to provide for the payment by me to you (in the manner designated by you) of your withholding obligation, if any, relating to the exercise of this option,
and (iii) if this exercise relates to an incentive stock option, to notify you in writing within fifteen (15) days after the date of any disposition of any of the Shares issued upon exercise of this option that occurs within two
(2) years after the date of grant of this option or within one (1) year after such Shares are issued upon exercise of this option. 
  

	
	 Very truly yours,

	
	  




  
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