Document:

EX-10.1

 Exhibit 10.1 

Execution Version 

AMENDMENT TO EMPLOYMENT AGREEMENT 

This Amendment to Employment Agreement (this “Amendment”) is effective as of March 6, 2017 (the “Amendment
Effective Date”), by and among Lyondell Chemical Company, a Delaware corporation (the “Company”), LyondellBasell Industries N.V., a public limited liability company formed under the laws of The Netherlands (the
“Parent Company”), and Bhavesh (Bob) V. Patel (the “Executive” and, together with the Company and the Parent Company, the “Parties”). 

W I T N E S S E T H: 

WHEREAS, the Company and Executive entered into that certain Employment Agreement dated December 18, 2014 but effective as of
January 12, 2015 (the “Agreement”); 
 WHEREAS, the Parties desire to amend the Agreement in the manner
reflected herein; 
 WHEREAS, the Compensation Committee of the Supervisory Board of the Parent Company has approved the amendment of
the Agreement in the manner reflected herein; and 
 NOW, THEREFORE, in consideration of the premises and mutual covenants and
conditions herein, the Parties, intending to be legally bound, hereby agree as follows, effective as of the Amendment Effective Date: 

1.    Term of Employment. Section 1 of the Agreement is hereby deleted and replaced in its entirety
with the following (with all capitalized terms having the meaning originally ascribed thereto in the Agreement): 
 “1. Term of
Employment. 
 (a) The Company agrees to employ Executive, and Executive agrees to be employed by the Company, pursuant
to the terms and conditions of this Agreement. The term of Executive’s employment by the Company pursuant to this Agreement shall commence as of the Effective Date of this Agreement and shall expire on December 31, 2018, subject to earlier
termination in accordance with Section 4 hereof (the “Initial Term”). 

(b)    Subject to earlier termination in accordance with Section 4 hereof, the term of
Executive’s employment pursuant to the terms of this Agreement shall continue in accordance with the terms of this Agreement for additional one-year terms (each, a “Renewal Term”),
after the Initial Term, unless either the Company or Executive provides written notice of termination to the other party at least 90 days (120 days for notice provided by Executive) before the commencement of a Renewal Term (“Notice of Non-Renewal”), in which case the term of employment shall terminate as of the 90th day (120th day in the case of notice provided by Executive)
immediately following the giving of such notice unless an earlier termination date is agreed to by the parties (the period during which Executive is employed hereunder is referred to as the “Term”).” 

 2.    Base Salary. Section 3(a) of the Agreement is amended to
reflect a Base Salary at an annualized rate of $1,500,000, beginning on January 1, 2017. 
 3.    Annual
Bonus. Section 3(b) of the Agreement is amended to reflect a target bonus amount of not less than 160% of Executive’s then current Base Salary. 

4.    LTI Awards. Section 3(c)(i) of the Agreement is amended to reflect that Executive’s LTI Awards
granted each fiscal year during the Term shall have an aggregate value of not less than 750% of the amount of Executive’s then current Base Salary, and shall otherwise be determined in accordance with the provisions of Section 3(c)(i) of the
Agreement. 
 5.    Severance Multiples. Section 4(c)(ii) of the Agreement is hereby deleted and replaced
in its entirety with the following (with all capitalized terms having the meaning originally ascribed thereto in the Agreement): 

“(ii)    A lump sum severance payment in an amount equal to the sum of Executive’s then current annual Base
Salary and Executive’s target Annual Bonus for the year of termination (the “Annual Compensation Amount”) multiplied by 1.50 (or in the event of an applicable termination of employment during a Protection Period (as
defined below), a severance payment in the amount equal to 2.50 times the Annual Compensation Amount), payable on the 60th day following the Date of Termination;” 

6.    Counterparts. This Amendment may be executed in one or more facsimile, electronic or original
counterparts, each of which shall be deemed an original and both of which together shall constitute the same instrument. 

7.    Ratification. All terms and provisions of the Agreement not amended hereby, either expressly or by
necessary implication, shall remain in full force and effect. From and after the date of this Amendment, all references to the term “Agreement” in this Amendment or the original Agreement shall include the terms contained in this
Amendment. 
 [Signatures begin on next page.] 

  
 2 

 Execution Version 

The Parties have executed this Amendment to Employment Agreement effective as of the Amendment Effective Date. 

 

			
	LYONDELLBASELL INDUSTRIES N.V.
		
	By:	 	 /s/ Jeffrey Kaplan

	Name:	 	Jeffrey A. Kaplan
	Title:	 	Executive Vice President and
		 	Chief Legal Officer
	
	LYONDELL CHEMICAL COMPANY
		
	By:	 	 /s/ Jeffrey Kaplan

	Name:	 	Jeffrey A. Kaplan
	Title:	 	Executive Vice President and
		 	Chief Legal Officer
	
	EXECUTIVE
	
	 /s/ Bhavesh Patel

	Bhavesh (Bob) V. Patel

  
 3EX-10.2

 Exhibit 10.2 

TOCAGEN INC. 

2009 EQUITY INCENTIVE PLAN 

ADOPTED BY THE BOARD: MARCH 23, 2009 

APPROVED BY THE STOCKHOLDERS: MARCH 23, 2009 

AMENDED BY THE BOARD: FEBRUARY 16, 2012 

APPROVED BY THE STOCKHOLDERS: FEBRUARY 16, 2012 

AMENDED BY THE BOARD: MARCH 10, 2014 

APPROVED BY THE STOCKHOLDERS: MARCH 10, 2014 

AMENDED BY THE BOARD: OCTOBER 21, 2014 

APPROVED BY THE STOCKHOLDERS: OCTOBER 21, 2014 

AMENDED BY THE BOARD: JUNE 10, 2016 

APPROVED BY THE STOCKHOLDERS: JUNE 10, 2016 

AMENDED BY THE BOARD: NOVEMBER 16, 2016 

APPROVED BY THE STOCKHOLDERS: NOVEMBER 16, 2016 

TERMINATION DATE: MARCH 22, 2019 

1. GENERAL. 

(a) Eligible Stock Award Recipients. The persons eligible to receive Stock Awards are Employees, Directors and
Consultants. 
 (b) Available Stock Awards. The Plan provides for the grant of the following Stock Awards:
(i) Incentive Stock Options, (ii) Nonstatutory Stock Options, (iii) Restricted Stock Awards, (iv) Restricted Stock Unit Awards, (v) Stock Appreciation Rights, (vi) Performance Stock Awards, and (vii) Other Stock
Awards. 
 (c) General Purpose. The Company, by means of the Plan, seeks to secure and retain the services of the
group of persons eligible to receive Stock Awards as set forth in Section 1(a), to provide incentives for such persons to exert maximum efforts for the success of the Company and any Affiliate and to provide a means by which such eligible
recipients may be given an opportunity to benefit from increases in value of the Common Stock through the granting of Stock Awards. 

2. DEFINITIONS. As used in the Plan, the following definitions shall 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 shall have the authority to determine the time or times at which “parent” or “subsidiary” status is determined within
the foregoing definition. 
 (b) “Board” means the Board of Directors of the
Company. 
 (c) “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 Effective Date without the receipt of consideration by the Company (through merger, consolidation, reorganization,
recapitalization, reincorporation, stock dividend, dividend in  

  
 1. 

 
property other than cash, stock split, liquidating dividend, combination of shares, exchange of shares, change in corporate structure or other transaction not involving the receipt of
consideration by the Company). Notwithstanding the foregoing, the conversion of any convertible securities of the Company shall not be treated as a transaction “without receipt of consideration” by the Company. 

(d) “Cause” means misconduct, including: (i) conviction of any felony or any
crime involving moral turpitude or dishonesty; (ii) participation in a fraud or act of dishonesty against the Company; (iii) willful and material breach of Participant’s duties that has not been cured within 30 days after written
notice from the Company’s Board of Directors of such breach; (iv) material breach of the Proprietary Information and Inventions Agreement that has not been cured within 30 days after written notice from the Company’s Board of
Directors of such breach; or (v) death or disability. 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 by reason of dismissal without Cause for the purposes of outstanding Stock 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. 
 (e)
“Change in Control” means (a) a sale of all or substantially all of the assets of the Company; (b) a merger or consolidation in which the Company is not the surviving corporation (other than a merger or
consolidation in which stockholders immediately before the merger or consolidation have, immediately after the merger or consolidation, a majority of the voting power of the surviving corporation); (c) a reverse merger in which the Company is
the surviving corporation but the shares of the Company’s Common Stock outstanding immediately preceding the merger are converted by virtue of the merger into other property, whether in the form of securities, cash or otherwise (other than a
reverse merger in which stockholders immediately before the merger have, immediately after the merger, a majority of the voting power of the surviving corporation); or (d) any transaction or series of related transactions in which in excess of
50% of the Company’s voting power is transferred, other than the sale by the Company of stock in transactions the primary purpose of which is to raise capital for the Company’s operations and activities. 

Notwithstanding the foregoing or any other provision of this Plan, the definition of Change in Control (or any
analogous term) in an individual written agreement approved by the Board between the Company or any Affiliate and the Participant shall supersede the foregoing definition with respect to Stock 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 shall apply. 

The Board may, in its sole discretion and without a Participant’s consent, amend the definition of “Change in
Control” to conform to the definition of “Change in Control” under Section 409A of the Code, and the regulations thereunder. 

(f) “Code” means the Internal Revenue Code of 1986, as amended. 

  
 2. 

 (g) “Committee” means a committee of one
(1) or more Directors to whom authority has been delegated by the Board in accordance with Section 3(c). 
 (h)
“Common Stock” means the common stock of the Company. 
 (i)
“Company” means Tocagen Inc., a Delaware corporation. 
 (j)
“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 as a Director, or payment of a fee for such service, shall not cause a Director to be considered a “Consultant” for purposes of the
Plan.  
 (k) “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, shall not terminate a Participant’s
Continuous Service; provided, however, if the corporation for which a Participant is rendering service ceases to qualify as an Affiliate, as determined by the Board in its sole discretion, such Participant’s Continuous Service shall be
considered to have terminated on the date such corporation ceases to qualify as an Affiliate. For example, a change in status, such as from an employee of the Company to a consultant to an Affiliate or to a Director, shall not constitute an
interruption of Continuous Service. 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 shall be considered interrupted in the case
of any leave of absence approved by that party, including sick leave, military leave or any other personal leave. Notwithstanding the foregoing, a leave of absence shall be treated as Continuous Service for purposes of vesting in a Stock Award only
to such extent as may be provided in the Company’s leave of absence policy or in the written terms of the Participant’s leave of absence agreement. 

(l) “Corporate Transaction” 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 consolidation or merger of the Company
with or into any other corporation or other entity or person, or any other corporate reorganization; 
 (ii) any
transaction or series of related transactions to which the Company is a party in which in excess of fifty percent (50%) of the Company’s voting power is transferred; or 

(iii) a sale, lease, exclusive license or other disposition of all or substantially all of the assets of the Company.

 (m) “Current Participants” has the meaning provided in Section 10(c)(ii). 

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

  
 3. 

 (o) “Disability” means the inability of a
Participant to engage in substantially gainful Company activity by reason of any medically determinable physical or mental impairment which can be expected to result in death or which has lasted or can be expected to last for a continuous period of
not less than twelve (12) months, and shall be determined by the Board on the basis of such medical evidence as the Board deems warranted under the circumstances. 

(p) “Effective Date” means the effective date of this Plan document, which is the date that
this Plan is first approved by the Company’s stockholders. 
 (q) “Employee” means any
person employed by the Company or an Affiliate. However, service as a Director, or payment of a fee for such services, shall not cause a Director to be considered an “Employee” for purposes of the Plan. 

(r) “Entity” means a corporation, partnership, limited liability company or other entity. 

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

(t) “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” shall 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 an 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 Effective Date as set forth in Section 12, is the Owner, directly or indirectly, of securities of the Company representing more than fifty percent (50%) of the combined
voting power of the Company’s then outstanding securities. 
 (u) “Fair Market Value”
means, as of any date, the value of the Common Stock determined by the Board in compliance with Section 409A of the Code or, in the case of an Incentive Stock Option, in compliance with Section 422 of the Code. 

(v) “Good Reason” means, with respect to any particular Participant, any of the following
actions taken without Cause by the Company or a successor corporation or entity without Participant’s consent: (i) substantial reduction of Participant’s (a) rate of cash compensation or (b) level of benefits pursuant to
Company benefit plans, provided that any reduction of either (a) or (b) which proportionately effects all or substantially all similarly ranked employees shall not constitute “Good Reason” for purposes of this Agreement;
(ii) failure or refusal of a successor to the Company to assume the Company’s obligations under this Agreement in the event of a Change in Control as defined below; or (iii) relocation of Participant’s principal place of
employment to a place greater than 50 miles from Participant’s then current principal place of employment. 

  
 4. 

 (w) “Incentive Stock Option” means an Option that
qualifies as an “incentive stock option” within the meaning of Section 422 of the Code and the regulations promulgated thereunder. 

(x) “JAMS” has the meaning provided in Section 3(f). 

(y) “Nonstatutory Stock Option” means any Option that does not qualify as an Incentive Stock
Option. 
 (z) “Officer” means any person designated by the Company as an officer. 

(aa) “Option” means an Incentive Stock Option or a Nonstatutory Stock Option to purchase shares
of Common Stock granted pursuant to the Plan. 
 (bb) “Option Agreement” means a written
agreement between the Company and an Optionholder evidencing the terms and conditions of an Option grant. Each Option Agreement shall be subject to the terms and conditions of the Plan. 

(cc) “Optionholder” means a person to whom an Option is granted pursuant to the Plan or, if
permitted under the terms of this Plan, such other person who holds an outstanding Option. 
 (dd) “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 7(d). 

(ee) “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 shall be subject to the terms and conditions of the Plan. 

(ff) “Own,” “Owned,” “Owner,” “Ownership” A person or Entity
shall 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; provided, however, that no such person or Entity shall be deemed to have relinquished
ownership of securities solely by virtue of having entered into an agreement granting to any other person or Entity power to vote or direct the voting of such securities. 

(gg) “Participant” means a person to whom a Stock Award is granted pursuant to
the Plan or, if applicable, such other person who holds an outstanding Stock Award. 
 (hh) “Performance
Stock Award” means a Stock Award granted under the terms and conditions of Section 7(d). 
 (ii)
“Plan” means this Tocagen Inc. 2009 Equity Incentive Plan. 

  
 5. 

 (jj) “Restricted Stock Award” means an award of
shares of Common Stock which is granted pursuant to the terms and conditions of Section 7(a). 
 (kk)
“Restricted Stock Award Agreement” means a written agreement between the Company and a holder of a Restricted Stock Award evidencing the terms and conditions of a Restricted Stock Award grant. Each Restricted Stock Award
Agreement shall be subject to the terms and conditions of the Plan. 
 (ll) “Restricted Stock Unit
Award” means a right to receive shares of Common Stock which is granted pursuant to the terms and conditions of Section 7(b). 

(mm) “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. Each Restricted Stock Unit Award Agreement shall be subject to the terms and conditions of the Plan.  

(nn) “Rule 701” has the meaning provided in Section 5(c). 

(oo) “Securities Act” means the Securities Act of 1933, as amended. 

(pp) “Share Reserve” has the meaning provided in Section 4(a). 

(qq) “Stock Appreciation Right” means a right to receive the appreciation on
Common Stock that is granted pursuant to the terms and conditions of Section 7(c). 
 (rr)
“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 shall be subject to the terms and conditions of the Plan. 
 (ss)
“Stock Award” means any right granted under the Plan, including an Option, a Restricted Stock Award, a Restricted Stock Unit Award, a Stock Appreciation Right, a Performance Stock Award or an Other Stock Award. 

(tt) “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 shall be subject to the terms and conditions of the Plan. 

(uu) “Subsidiary” means, with respect to the Company, (i) any corporation of
which more than fifty percent (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 shall 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 fifty percent (50%). 

  
 6. 

 (vv) “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 ten percent (10%) of the total combined voting power of all classes of stock of the Company or any Affiliate. 

3. ADMINISTRATION. 

(a) Administration by Board. The Board shall administer the Plan unless and until the Board delegates administration of
the Plan to a Committee, as provided in Section 3(c). 
 (b) Powers of Board. The Board or the Committee, to the
extent delegated to the Committee pursuant to Section 3(c), shall have the power, subject to, and within the limitations of, the express provisions of the Plan: 

(i) To determine from time to time (A) which of the persons eligible under the Plan shall be granted Stock Awards;
(B) when and how each Stock Award shall be granted; (C) what type or combination of types of Stock Award shall be granted; (D) the provisions of each Stock Award granted (which need not be identical), including the time or times when
a person shall be permitted to receive cash or Common Stock pursuant to a Stock Award; and (E) the number of shares of Common Stock with respect to which a Stock Award shall be granted to each such person. 

(ii) To construe and interpret the Plan and Stock Awards granted under it, and to establish, amend and revoke rules and
regulations for its administration. The Board, in the exercise of this power, may correct any defect, omission or inconsistency in the Plan or in any Stock Award Agreement, in a manner and to the extent it shall deem necessary or expedient to make
the Plan or Stock Award fully effective. 
 (iii) To settle all controversies regarding the Plan and Stock Awards
granted under it. 
 (iv) To accelerate the time at which a Stock Award may first be exercised or the time during
which a Stock Award or any part thereof will vest in accordance with the Plan, notwithstanding the provisions in the Stock Award stating the time at which it may first be exercised or the time during which it will vest. 

(v) To suspend or terminate the Plan at any time. Suspension or termination of the Plan shall not impair rights and
obligations under any Stock Award granted while the Plan is in effect except with the written consent of the affected Participant. 

(vi) To amend the Plan, subject to the limitations, if any, of applicable law. However, except as provided in
Section 10(a) relating to Capitalization Adjustments, no amendment shall be effective unless approved by the stockholders of the Company to the extent stockholder approval is necessary to satisfy applicable law. Rights under any Stock Award
granted before amendment of the Plan shall not be impaired by any amendment of the Plan unless (i) the Company requests the consent of the affected Participant, and (ii) such Participant consents in writing. 

(vii) To submit any amendment to the Plan for stockholder approval. 

  
 7. 

 (viii) To amend the Plan in any respect the Board deems necessary or
advisable to provide eligible Employees with the maximum benefits provided or to be provided under the provisions of the Code and the regulations promulgated thereunder relating to Incentive Stock Options or to bring the Plan or Incentive Stock
Options granted under it into compliance therewith. 
 (ix) To amend the terms of any one or more Stock Awards,
including, but not limited to, amendments to provide terms more favorable than previously provided in the Stock Award Agreement, subject to any specified limits in the Plan that are not subject to Board discretion; provided, however, that the
rights under any Stock Award shall not be impaired by any such amendment unless (i) the Company requests the consent of the affected Participant, and (ii) such Participant consents in writing. Notwithstanding the foregoing, subject to the
limitations of applicable law, if any, and without the affected Participant’s consent, the Board may amend the terms of any one or more Stock Awards if necessary to maintain the qualified status of the Stock Award as an Incentive Stock Option
or to bring the Stock Award into compliance with Section 409A of the Code and Department of Treasury regulations and other interpretive guidance issued thereunder. 

(x) 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 Stock Awards. 

(xi) 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. 
 (xii) To
effect, at any time and from time to time, with the consent of any adversely affected Participant, (1) the reduction of the exercise price of any outstanding Option or the strike price of any outstanding Stock Appreciation Right under the Plan;
(2) the cancellation of any outstanding Option or Stock Appreciation Right under the Plan and the grant in substitution therefor of (a) a new Option or Stock Appreciation Right under the Plan or another equity plan of the Company covering
the same or a different number of shares of Common Stock, (b) a Restricted Stock Award, (c) a Restricted Stock Unit Award, (d) an Other Stock Award, (e) cash, and/or (f) other valuable consideration (as determined by the
Board, in its sole discretion); or (3) any other action that is treated as a repricing under generally accepted accounting principles. 

(c) Delegation to Committee. The Board may delegate some or all of the administration of the Plan to a Committee
or Committees. If administration is delegated to a Committee, the Committee shall 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 any of the administrative powers the Committee is authorized to exercise (and references in this Plan to the Board shall thereafter be to the Committee or subcommittee), subject, however, to such resolutions, not
inconsistent with the provisions of the Plan, as may be adopted from time to time by the Board. 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. 

  
 8. 

 (d) Delegation to an Officer. The Board may delegate to one or more
Officers of the Company the authority to do one or both of the following (i) designate Officers and Employees of the Company or any of its Subsidiaries to be recipients of Stock Awards and the terms thereof, and (ii) determine the number
of shares of Common Stock to be subject to Stock Awards granted to such Officers and Employees; provided, however, that the Board resolutions regarding such delegation shall 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. Notwithstanding anything to the contrary in this Section 3(d), the Board may not delegate to an Officer authority to
determine the Fair Market Value of the Common Stock pursuant to Section 2(u) above. 
 (e) Effect of Board’s
Decision. All determinations, interpretations and constructions made by the Board (or any Committee) in good faith shall not be subject to review by any person and shall be final, binding and conclusive on all persons. 

(f) Arbitration. Any dispute or claim concerning any Stock Awards granted (or not granted) pursuant to the Plan or any
disputes or claims relating to or arising out of the Plan shall be fully, finally and exclusively resolved by binding and confidential arbitration conducted pursuant to the rules of Judicial Arbitration and Mediation Services, Inc.
(“JAMS”) in San Diego, California. All arbitration fees shall be divided pro rata among the respective parties to such arbitration. In addition to any other relief, the arbitrator may award to the prevailing party recovery of
its attorneys’ fees and costs. By accepting a Stock Award, Participants and the Company waive their respective rights to have any such disputes or claims tried by a judge or jury. 

4. SHARES SUBJECT TO THE PLAN. 

(a) Share Reserve. Subject to the provisions of Section 10(a) relating to Capitalization Adjustments, the number of
shares of Common Stock that may be issued pursuant to Stock Awards shall not exceed, in the aggregate, Eleven Million One Hundred Fifty-nine Thousand Three Hundred (11,159,300) shares of Common Stock (the “Share
Reserve”). 
 (b) Reversion of Shares to the Share Reserve. If any (i) Stock Award shall for any
reason expire or otherwise terminate, in whole or in part, without having been exercised in full, (ii) shares of Common Stock issued to a Participant pursuant to a Stock Award are forfeited to or repurchased by the Company pursuant to the
Company’s reacquisition or repurchase rights under the Plan, including any forfeiture or repurchase caused by the failure to meet a contingency or condition required for the vesting of such shares, or (iii) Stock Award is settled in cash,
or (iv) shares of Common Stock are cancelled in accordance with the cancellation and regrant provisions of Section 3(b)(xii), then the shares of Common Stock not issued under such Stock Award, or forfeited to or repurchased by the Company,
shall revert to and again become available for issuance under the Plan. 
 If any shares subject to a Stock Award are not
delivered to a Participant because the Stock Award is exercised through a reduction of shares subject to the Stock Award (i.e., “net exercised”) or an appreciation distribution in respect of a Stock Appreciation Right is paid in
shares of Common Stock, the number of shares subject to the Stock Award that are not delivered 

  
 9. 

 
to the Participant shall remain available for subsequent issuance under the Plan. If any shares subject to a Stock Award are not delivered to a Participant because such shares are withheld in
satisfaction of the withholding of taxes incurred in connection with the exercise of an Option or Stock Appreciation Right or the issuance of shares under a Restricted Stock Award, Restricted Stock Unit Award or Other Stock Award, the number of
shares that are not delivered to the Participant shall remain available for subsequent issuance under the Plan. If the exercise price of any Stock Award is satisfied by tendering shares of Common Stock held by the Participant (either by actual
delivery or attestation), then the number of shares so tendered shall remain available for subsequent issuance under the Plan. 

(c) Incentive Stock Option Limit. Notwithstanding anything to the contrary in this Section 4, subject to the
provisions of Section 10(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 shall be double the number of shares of Common
Stock in the Share Reserve. 
 (d) Source of Shares. The stock issuable under the Plan shall be shares of authorized
but unissued or reacquired Common Stock, including shares repurchased by the Company. 
 5. ELIGIBILITY. 

(a) Eligibility for Specific Stock Awards. Incentive Stock Options may be granted only to Employees. Stock Awards other
than Incentive Stock Options may be granted to Employees, Directors and Consultants. 
 (b) Ten Percent Stockholders.
A Ten Percent Stockholder shall not be granted an Incentive Stock Option unless the exercise price of such Option is at least one hundred ten percent (110%) of the Fair Market Value of the Common Stock on the date of grant and the Option is not
exercisable after the expiration of five (5) years from the date of grant. 
 (c) Consultants. A Consultant
shall not be eligible for the grant of a Stock Award if, at the time of grant, either the offer or the sale of the Company’s securities to such Consultant is not exempt under Rule 701 of the Securities Act (“Rule 701”)
because of the nature of the services that the Consultant is providing to the Company, because the Consultant is not a natural person, or because of any other provision of Rule 701, unless the Company determines that such grant need not comply with
the requirements of Rule 701 and will satisfy another exemption under the Securities Act as well as comply with the securities laws of all other relevant jurisdictions. 

6. OPTION PROVISIONS. 

Each Option shall be in such form and shall contain such terms and conditions as the Board shall deem appropriate. All Options
shall 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 shall 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, then the Option shall be a Nonstatutory Stock Option. The provisions of separate Options need not be identical; provided, however, that each Option
Agreement shall include 

  
 10. 

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

(a) Term. No Option shall be exercisable after the expiration of ten (10) years from the date of its grant or such
shorter period specified in the Option Agreement; provided, however, that an Incentive Stock Option granted to a Ten Percent Stockholder shall be subject to the provisions of Section 5(b). 

(b) Exercise Price. Subject to the provisions of Section 5(b) regarding Incentive Stock Options granted to Ten
Percent Stockholders, the exercise price of each Option shall be not less than one hundred percent (100%) of the Fair Market Value of the Common Stock subject to the Option on the date the Option is granted. Notwithstanding the foregoing, an
Option may be granted with an exercise price lower than that set forth in the preceding sentence if such Option is granted pursuant to an assumption of or substitution for another option in a manner consistent with the provisions of
Section 424(a) of the Code (whether or not such options are Incentive Stock Options) or is otherwise granted in a manner designed to satisfy the requirements of Section 409A of the Code and applicable securities laws. 

(c) Consideration. The purchase price of Common Stock acquired pursuant to the exercise of an Option shall 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 shall 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 utilize a particular method of payment. The methods of payment permitted by this Section 6(c) are:

 (i) by cash or check; 

(ii) bank draft or money order payable to the Company; 

(iii) 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; 

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

(v) by a “net exercise” arrangement pursuant to which the Company will reduce the number of shares of Common
Stock issued 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 shall 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; provided, further, however, that shares of Common Stock will no longer be outstanding under an Option
and will not be exercisable thereafter to the extent that (A) shares 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 

  
 11. 

 (vi) in any other form of legal consideration that may be acceptable to
the Board. 
 (d) Transferability of Options. The Board may, in its sole discretion, impose such limitations on the
transferability of Options as the Board shall determine. In the absence of such a determination by the Board or provisions of the Option Agreement to the contrary, the following restrictions on the transferability of Options shall apply: 

(i) Restrictions on Transfer. An Option shall not be transferable except by will or by the laws of descent and
distribution and shall be exercisable during the lifetime of the Optionholder only by the Optionholder; provided, however, that the Board may, in its sole discretion, permit transfer of the Option to such extent as permitted by Rule 701 of
the Securities Act at the time of the grant of the Option and in a manner consistent with applicable tax and securities laws. 

(ii) Domestic Relations Orders. Notwithstanding the foregoing, an Option may be transferred pursuant to a domestic
relations order; provided, however, that if an Option is an Incentive Stock Option, such Option shall be deemed to be a Nonstatutory Stock Option as a result of such transfer. 

(iii) Beneficiary Designation. Notwithstanding the foregoing, the Optionholder may, by delivering written notice to the
Company, in a form provided by or otherwise satisfactory to the Company, designate a third party who, in the event of the death of the Optionholder, shall thereafter be entitled to exercise the Option. In the absence of such a designation, the
executor or administrator of the Optionholder’s estate shall be entitled to exercise the Option. 
 (e) Vesting
Generally. The total number of shares of Common Stock subject to an Option may vest and therefore become exercisable in periodic installments that may or may not be equal. The Option 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 may vary. The provisions of this
Section 6(e) are subject to any Option provisions governing the minimum number of shares of Common Stock as to which an Option may be exercised. 

(f) Termination of Continuous Service. In the event that an Optionholder’s Continuous Service terminates (other
than for Cause or upon the Optionholder’s death or Disability), the Optionholder may exercise his or her Option (to the extent that the Optionholder was entitled to exercise such Option as of the date of termination of Continuous Service) but
only within such period of time ending on the earlier of (i) the date three (3) months following the termination of the Optionholder’s Continuous Service (or such longer or shorter period specified in the Option Agreement, which
period shall not be less than thirty (30) days unless such termination is for cause), or (ii) the expiration of the term of the Option as set forth in the Option Agreement. If, after termination of Continuous Service, the Optionholder does
not exercise his or her Option within the time specified herein or in the Option Agreement (as applicable), the Option shall terminate. 

  
 12. 

 (g) Extension of Termination Date. An Optionholder’s Option Agreement
may provide that if the exercise of the Option following the termination of the Optionholder’s Continuous Service (other than for Cause or upon the Optionholder’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 shall terminate on the earlier of (i) the expiration of a period of three (3) months after the termination of the
Optionholder’s Continuous Service during which the exercise of the Option would not be in violation of such registration requirements, or (ii) the expiration of the term of the Option as set forth in the Option Agreement. 

(h) Disability of Optionholder. In the event that an Optionholder’s Continuous Service terminates as a result of
the Optionholder’s Disability, the Optionholder may exercise his or her Option (to the extent that the Optionholder was entitled to exercise such Option as of the date of termination of Continuous Service), but only within such period of time
ending on the earlier of (i) the date twelve (12) months following such termination of Continuous Service (or such longer or shorter period specified in the Option Agreement, which period shall not be less than six (6) months)), or
(ii) the expiration of the term of the Option as set forth in the Option Agreement. If, after termination of Continuous Service, the Optionholder does not exercise his or her Option within the time specified herein or in the Option Agreement
(as applicable), the Option shall terminate. 
 (i) Death of Optionholder. In the event that (i) an
Optionholder’s Continuous Service terminates as a result of the Optionholder’s death, or (ii) the Optionholder dies within the period (if any) specified in the Option Agreement after the termination of the Optionholder’s
Continuous Service for a reason other than death, then the Option may be exercised (to the extent the Optionholder was entitled to exercise such Option as of the date of death) by the Optionholder’s estate, by a person who acquired the right to
exercise the Option by bequest or inheritance or by a person designated to exercise the option upon the Optionholder’s death, but only within the period ending on the earlier of (i) the date eighteen (18) months following the date of
death (or such longer or shorter period specified in the Option Agreement, which period shall not be less than six (6) months), or (ii) the expiration of the term of such Option as set forth in the Option Agreement. If, after the
Optionholder’s death, the Option is not exercised within the time specified herein or in the Option Agreement (as applicable), the Option shall terminate. 

(j) Termination for Cause. Except as explicitly provided otherwise in an Optionholder’s Option Agreement, in the
event that an Optionholder’s Continuous Service is terminated for Cause, the Option shall terminate upon the termination date of such Optionholder’s Continuous Service, and the Optionholder shall be prohibited from exercising his or her
Option from and after the time of such termination of Continuous Service. 
 (k) Non-Exempt Employees. No Option
granted to an Employee that is a non-exempt employee for purposes of the Fair Labor Standards Act shall be first exercisable for any shares of Common Stock until at least six months following the date of grant of the Option. 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 will be exempt from his or her regular rate of pay.  

  
 13. 

 (l) Early Exercise. The Option may, but need not, include a provision
whereby the Optionholder may elect at any time before the Optionholder’s Continuous Service terminates to exercise the Option as to any part or all of the shares of Common Stock subject to the Option prior to the full vesting of the Option.
Subject to the “Repurchase Limitation” in Section 9(i), any unvested shares of Common Stock so purchased may be subject to a repurchase option in favor of the Company or to any other restriction the Board determines to be appropriate.
 
 (m) Right of Repurchase. Subject to the “Repurchase Limitation” in Section 9(i), the Option
may, but need not, include a provision whereby the Company may elect to repurchase all or any part of the vested shares of Common Stock acquired by the Optionholder pursuant to the exercise of the Option.  

(n) Right of First Refusal. The Option may, but need not, include a provision whereby the Company may elect to exercise
a right of first refusal following receipt of notice from the Optionholder of the intent to transfer all or any part of the shares of Common Stock received upon the exercise of the Option. Such right of first refusal shall be subject to the
“Repurchase Limitation” in Section 9(i). Except as expressly provided in this Section 6(n) or in the Stock Award Agreement for the Option, such right of first refusal shall otherwise comply with any applicable provisions of the
Bylaws of the Company.  
 7. PROVISIONS OF STOCK AWARDS
OTHER THAN OPTIONS. 
 (a) Restricted Stock Awards. Each Restricted
Stock Award Agreement shall be in such form and shall contain such terms and conditions as the Board shall deem appropriate. To the extent consistent with the Company’s Bylaws, at the Board’s election, shares of Common Stock may be
(i) held in book entry form subject to the Company’s instructions until any restrictions relating to the Restricted Stock Award lapse; or (ii) evidenced by a certificate, which certificate shall 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; provided, however, that
each Restricted Stock Award Agreement shall include (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 (i) past or future services
rendered to the Company or an Affiliate, or (ii) any other form of legal consideration that may be acceptable to the Board, in its sole discretion, and permissible under applicable law. A Restricted Stock Award may be awarded as a stock bonus
(i.e., with no cash purchase price to be paid) to the extent permissible under applicable law. 
 (ii)
Vesting. Subject to the repurchase limitation in Section 9(i), shares of Common Stock acquired under a Restricted Stock Award may be subject to forfeiture to the Company in accordance with a vesting schedule to be determined by the Board.

 (iii) Termination of Continuous Service. Subject to the repurchase limitation in Section 9(i), in the event a
Participant’s Continuous Service terminates, the Company may receive, pursuant to a forfeiture condition, any or all of the shares of Common Stock held by the  

  
 14. 

 
Participant which 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 shall be
transferable by the Participant only upon such terms and conditions as are set forth in the Restricted Stock Award Agreement, as the Board shall 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. 
 (b) Restricted Stock Unit
Awards. Each Restricted Stock Unit Award Agreement shall be in such form and shall contain such terms and conditions as the Board shall 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, provided, however, that each Restricted Stock Unit Award Agreement shall include (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 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 the terms
and conditions of the underlying Restricted Stock Unit Award Agreement to which they relate. 

  
 15. 

 (vi) Termination of 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. 

(vii) Compliance with Section 409A of the Code. Notwithstanding anything to the contrary set forth herein, any
Restricted Stock Unit Award granted under the Plan that is not exempt from the requirements of Section 409A of the Code shall contain such provisions so that such Restricted Stock Unit Award will comply with the requirements of
Section 409A of the Code. Such restrictions, if any, shall be determined by the Board and contained in the Restricted Stock Unit Award Agreement evidencing such Restricted Stock Unit Award. For example, such restrictions may include, without
limitation, a requirement that any Common Stock that is to be issued in a year following the year in which the Restricted Stock Unit Award vests must be issued in accordance with a fixed pre-determined schedule.  

(c) Stock Appreciation Rights. Each Stock Appreciation Right Agreement shall be in such form and shall contain such
terms and conditions as the Board shall deem appropriate. Stock Appreciation Rights may be granted as stand-alone Stock Awards or in tandem with other Stock Awards. The terms and conditions of Stock Appreciation Right Agreements may change from time
to time, and the terms and conditions of separate Stock Appreciation Right Agreements need not be identical; provided, however, that each Stock Appreciation Right Agreement shall include (through incorporation of the provisions hereof by
reference in the Agreement or otherwise) the substance of each of the following provisions: 
 (i) Term. No Stock
Appreciation Right shall be exercisable after the expiration of ten (10) years from the date of its grant or such shorter period specified in the Stock Appreciation Right Agreement. 

(ii) Strike Price. Each Stock Appreciation Right will be denominated in shares of Common Stock equivalents. The strike
price of each Stock Appreciation Right granted as a stand-alone or tandem Stock Award shall not be less than one hundred percent (100%) of the Fair Market Value of the Common Stock equivalents subject to the Stock Appreciation Right on the date
of grant. 
 (iii) Calculation of Appreciation. The appreciation distribution payable on the exercise of a Stock
Appreciation Right 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 Stock Appreciation Right) of a number of shares of Common Stock equal to the number of share of
Common Stock equivalents in which the Participant is vested under such Stock Appreciation Right, and with respect to which the Participant is exercising the Stock Appreciation Right on such date, over (B) the strike price that will be
determined by the Board at the time of grant of the Stock Appreciation Right. 
 (iv) Vesting. At the time of the
grant of a Stock Appreciation Right, the Board may impose such restrictions or conditions to the vesting of such Stock Appreciation Right as it, in its sole discretion, deems appropriate; provided, however, that a Stock Appreciation Right
that may be settled in shares of Common Stock shall be subject to the provision of Section 9(i). 

  
 16. 

 (v) Exercise. To exercise any outstanding Stock Appreciation Right, the
Participant must provide written notice of exercise to the Company in compliance with the provisions of the Stock Appreciation Right Agreement evidencing such Stock Appreciation Right. 

(vi) Non-Exempt Employees. No Stock Appreciation Right granted to an Employee that is a non-exempt employee for
purposes of the Fair Labor Standards Act of 1938, as amended, shall be first exercisable for any shares of Common Stock until at least six months following the date of grant of the Stock Appreciation Right. The foregoing provision is intended to
operate so that any income derived by a non-exempt employee in connection with the exercise of a Stock Appreciation Right will be exempt from his or her regular rate of pay. 

(vii) Payment. The appreciation distribution in respect of a Stock Appreciation Right 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 set forth in the Stock Appreciation Right Agreement evidencing such Stock Appreciation Right. 

(viii) Termination of Continuous Service. In the event that a Participant’s Continuous Service terminates (other
than for Cause or upon the Participant’s death or Disability), the Participant may exercise his or her Stock Appreciation Right (to the extent that the Participant was entitled to exercise such Stock Appreciation Right as of the date of
termination of Continuous Service) but only within such period of time ending on the earlier of (A) the date three (3) months following the termination of the Participant’s Continuous Service (or such longer or shorter period
specified in the Stock Appreciation Right Agreement, which period shall not be less than thirty (30) days unless such termination is for cause), or (B) the expiration of the term of the Stock Appreciation Right as set forth in the Stock
Appreciation Right Agreement. If, after termination of Continuous Service, the Participant does not exercise his or her Stock Appreciation Right within the time specified herein or in the Stock Appreciation Right Agreement (as applicable), the Stock
Appreciation Right shall terminate. 
 (ix) Termination for Cause. Except as explicitly provided otherwise in an
Participant’s Stock Appreciation Right Agreement, in the event that a Participant’s Continuous Service is terminated for Cause, the Stock Appreciation Right shall terminate upon the termination date of such Participant’s Continuous
Service, and the Participant shall be prohibited from exercising his or her Stock Appreciation Right from and after the time of such termination of Continuous Service. 

(x) Extension of Termination Date. A Participant’s Stock Appreciation Right Agreement may provide that if the
exercise of the Stock Appreciation Right following the termination of the Participant’s Continuous Service (other than upon the Participant’s death, or Disability, or upon a Change in Control, if applicable) 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 Stock Appreciation Right shall terminate on the earlier of (i) the expiration of a period of three
(3) months after the termination of the Participant’s Continuous Service during which the exercise of the Stock Appreciation Right would not be in violation of such registration requirements, or (ii) the expiration of the term of the
Stock Appreciation Right as set forth in the Stock Appreciation Right Agreement. 

  
 17. 

 (xi) Disability of Participant. In the event that a Participant’s
Continuous Service terminates as a result of the Participant’s Disability, the Participant may exercise his or her Stock Appreciation Right (to the extent that the Participant was entitled to exercise such Stock Appreciation Right as of the
date of termination of Continuous Service), but only within such period of time ending on the earlier of (i) the date twelve (12) months following such termination of Continuous Service (or such longer or shorter period specified in the
Stock Appreciation Right Agreement, which period shall not be less than six (6) months), or (ii) the expiration of the term of the Stock Appreciation Right as set forth in the Stock Appreciation Right Agreement. If, after termination of
Continuous Service, the Participant does not exercise his or her Stock Appreciation Right within the time specified herein or in the Stock Appreciation Right Agreement (as applicable), the Stock Appreciation Right shall terminate. 

(xii) Death of Participant. In the event that (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 Stock Appreciation Right Agreement after the termination of the Participant’s Continuous Service for a reason other than death, the
Stock Appreciation Right may be exercised (to the extent that the Participant was entitled to exercise such Stock Appreciation Right as of the date of death) by the Participant’s estate, by a person who acquired the right to exercise the Stock
Appreciation Right by bequest or inheritance or by a person designated to exercise the option upon the Participant’s death, but only within the period ending on the earlier of (i) the date eighteen (18) months following the date of
death (or such longer or shorter period specified in the Stock Appreciation Right Agreement, which period shall not be less than six (6) months), or (ii) the expiration of the term of such Stock Appreciation Right as set forth in the Stock
Appreciation Right Agreement. If, after the Participant’s death, the Stock Appreciation Right is not exercised within the time specified herein or in the Stock Appreciation Right Agreement (as applicable), the Stock Appreciation Right shall
terminate. 
 (xiii) Compliance with Section 409A of the Code. Notwithstanding anything to the contrary
set forth herein, any Stock Appreciation Rights granted under the Plan that are not exempt from the requirements of Section 409A of the Code shall contain such provisions so that such Stock Appreciation Rights will comply with the requirements
of Section 409A of the Code. Such restrictions, if any, shall be determined by the Board and contained in the Stock Appreciation Right Agreement evidencing such Stock Appreciation Right. For example, such restrictions may include, without
limitation, a requirement that a Stock Appreciation Right that is to be paid wholly or partly in cash must be exercised and paid in accordance with a fixed pre-determined schedule. 

(d) Performance Stock Awards. A Performance Stock Award is either a Restricted Stock Award or Restricted Stock Unit
Award that may be granted, may vest, or may be exercised based upon the attainment during a period of time selected by the Board of one or more performance goals established by the Board. Performance Stock Awards may also require the completion of a
specified period of Continuous Service. The length of any period over which the attainment of performance goals are measured, the performance goals to be achieved during such period, and the measure of whether and to what degree such performance
goals have been attained shall be conclusively determined by the Board, in its sole discretion. 

  
 18. 

 (e) Other Stock Awards. Other forms of Stock Awards valued in whole or in
part by reference to, or otherwise based on, Common Stock may be granted either alone or in addition to Stock Awards provided for under Section 6 and the preceding provisions of this Section 7. Subject to the provisions of the Plan, the
Board shall have sole and complete authority to determine the persons to whom and the time or times at which such Other Stock Awards will be granted, the number of shares of Common Stock (or the cash equivalent thereof) to be granted pursuant to
such Other Stock Awards and all other terms and conditions of such Other Stock Awards.  
 8. COVENANTS
OF THE COMPANY. 
 (a) Availability of Shares. During the terms of
the Stock Awards, the Company shall keep available at all times the number of shares of Common Stock required to satisfy such Stock Awards. 

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

9. MISCELLANEOUS. 

(a) Use of Proceeds from Sales of Common Stock. Proceeds from the sale of shares of Common Stock pursuant to Stock
Awards shall constitute general funds of the Company. 
 (b) Corporate Action Constituting Grant of Stock
Awards. Corporate action constituting an offer by the Company of Common Stock to any Participant under the terms of a Stock Award shall 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 Stock Award is actually received or accepted by the Participant.  

(c) Stockholder Rights. No Participant shall 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 such  

  
 19. 

 
Stock Award unless and until such Participant has satisfied all requirements for exercise of the Stock Award pursuant to its terms. 

(d) No Employment or Other Service Rights. Nothing in the Plan or any Stock Award Agreement shall confer upon any
Participant any right to continue to serve the Company or an Affiliate in the capacity in effect at the time the Stock Award was granted or shall 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) Incentive Stock Option $100,000 Limitation. 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 one hundred thousand dollars
($100,000), the Options or portions thereof that exceed such limit (according to the order in which they were granted) shall be treated as Nonstatutory Stock Options, notwithstanding any contrary provision of the applicable Option Agreement(s).

 (f) Investment Assurances. The Company may require a Participant, as a condition of exercising or acquiring
Common Stock under any Stock 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 he or she is capable of evaluating, alone or together with the purchaser representative, the merits and risks of exercising the Stock Award;
and (ii) to give written assurances satisfactory to the Company stating that the Participant is acquiring Common Stock subject to the Stock 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, shall be inoperative if (x) the issuance of the shares upon the exercise or acquisition of Common Stock under the Stock Award has
been registered under a then currently effective registration statement under the Securities Act, or (y) 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. 

(g) Withholding Obligations. To the extent provided by the terms of a Stock Award Agreement, the Company may, in its
sole discretion, satisfy any federal, state or local tax withholding obligation relating to a Stock Award by any of the following means (in addition to the Company’s right to withhold from any compensation paid to the Participant by the
Company) or by a combination of such means: (i) causing the Participant to tender a cash payment; (ii) withholding shares of Common Stock from the shares of Common Stock issued or otherwise issuable to the Participant in connection with
the Stock Award; provided, however, that no shares 

  
 20. 

 
of Common Stock are withheld with a value exceeding the minimum amount of tax required to be withheld by law (or such lower amount as may be necessary to avoid classification of the Stock Award
as a liability); or (iii) by such other method as may be set forth in the Stock Award Agreement. 
 (h) Electronic
Delivery. Any reference herein to a “written” agreement or document shall include any agreement or document delivered electronically or posted on the Company’s intranet. 

(i) Repurchase Limitation. The terms of any repurchase option shall be specified in the Stock Award Agreement. The
repurchase price for vested shares of Common Stock shall be the Fair Market Value of the shares of Common Stock on the date of repurchase. The repurchase price for unvested shares of Common Stock shall be the lower of (i) the Fair Market Value
of the shares of Common Stock on the date of repurchase or (ii) their original purchase price. However, the Company shall not exercise its repurchase option until at least six (6) months (or such longer or shorter period of time necessary
to avoid classification of the Stock Award as a liability for financial accounting purposes) have elapsed following delivery of shares of Common Stock subject to the Stock Award, unless otherwise specifically provided by the Board. 

(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 Stock 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. The Board is authorized to make deferrals
of Stock Awards and determine when, and in what annual percentages, Participants may receive payments, including lump sum payments, following the Participant’s termination of employment or retirement, 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. To the extent that the Board determines that any Award granted under the Plan is subject to Section 409A of the Code, the Award Agreement evidencing such Award shall incorporate the terms and conditions necessary to
avoid the consequences described in Section 409A(a)(1) of the Code. To the extent applicable, the Plan and Award Agreements shall be interpreted in accordance with Section 409A of the Code and Department of Treasury regulations and other
interpretive guidance issued thereunder, including without limitation any such regulations or other guidance that may be issued or amended after the Effective Date. Notwithstanding any provision of the Plan to the contrary, in the event that
following the Effective Date the Board determines that any Award may be subject to Section 409A of the Code and related Department of Treasury guidance (including such Department of Treasury guidance as may be issued after the Effective Date),
the Board may adopt such amendments to the Plan and the applicable Award Agreement or adopt other policies and procedures (including amendments, policies and procedures with retroactive effect), or take any other actions, that the Board determines
are necessary or appropriate to (1) exempt the Award from Section 409A of the Code and/or preserve the intended tax treatment of the benefits 

  
 21. 

 
provided with respect to the Award, or (2) comply with the requirements of Section 409A of the Code and related Department of Treasury guidance. 

10. ADJUSTMENTS UPON CHANGES IN COMMON STOCK;
OTHER CORPORATE EVENTS. 
 (a) Capitalization Adjustments. In the
event of a Capitalization Adjustment, the Board shall proportionately and appropriately adjust: (i) the class(es) and maximum number of securities subject to the Plan pursuant to Section 4(a), (ii) the class(es) and maximum number of
securities that may be issued pursuant to the exercise of Incentive Stock Options pursuant to Section 4(c), and (iii) the class(es) and number of securities and price per share of stock subject to outstanding Stock Awards. The Board shall
make such adjustments, and its determination shall be final, binding and conclusive. (Notwithstanding the foregoing, the conversion of any convertible securities of the Company shall not be treated as a transaction “without receipt of
consideration” by the Company.)  
 (b) Dissolution or Liquidation. In the event of a dissolution or
liquidation 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) shall terminate
immediately prior to the completion of such dissolution or liquidation, and the shares of Common Stock subject to the Company’s repurchase option may be repurchased by the Company notwithstanding the fact that the holder of such Stock Award is
providing Continuous Service, provided, however, that the Board may, in its sole discretion, cause some or all Stock Awards to become fully vested, exercisable and/or no longer subject to repurchase or forfeiture (to the extent
such Stock Awards have not previously expired or terminated) before the dissolution or liquidation is completed but contingent on its completion.  

(c) Corporate Transaction. The following provisions shall apply to Stock Awards in the event of a Corporate Transaction
unless otherwise provided in a written agreement between the Company or any Affiliate and the holder of the Stock Award:  

(i) Stock Awards May Be Assumed. In the event of a Corporate Transaction, any surviving corporation or acquiring
corporation (or the surviving or acquiring corporation’s parent company) may assume or continue any or all Stock Awards outstanding under the Plan or may substitute similar stock awards for Stock Awards outstanding under the Plan (including but
not limited to, awards to acquire the same consideration paid to the stockholders of the Company pursuant to the Corporate Transaction), and any reacquisition or repurchase rights held by the Company in respect of Common Stock issued pursuant to
Stock Awards may be assigned by the Company to the successor of the Company (or the successor’s parent company, if any), in connection with such Corporate Transaction. A surviving corporation or acquiring corporation (or its parent) may choose
to assume or continue only a portion of a Stock Award or substitute a similar stock award for only a portion of a Stock Award. The terms of any assumption, continuation or substitution shall be set by the Board in accordance with the provisions of
Section 3. 
 (ii) Stock Awards Held by Current Participants. In the event of a Corporate Transaction in which
the surviving corporation or acquiring corporation (or its parent company) does not assume or continue such outstanding Stock Awards or substitute similar  

  
 22. 

 
stock awards for such outstanding Stock Awards, then with respect to Stock Awards that have not been assumed, continued or substituted and that are held by Participants whose Continuous
Service has not terminated prior to the effective time of the Corporate Transaction (referred to as the “Current Participants”), the vesting of such Stock Awards (and, with respect to Options and Stock Appreciation Rights,
the time at which such Stock Awards may be exercised) shall (contingent upon the effectiveness of the Corporate Transaction) be accelerated in full to a date prior to the effective time of such Corporate Transaction as the Board shall determine (or,
if the Board shall not determine such a date, to the date that is five (5) days prior to the effective time of the Corporate Transaction), and such Stock Awards shall terminate if not exercised (if applicable) at or prior to the effective time
of the Corporate Transaction, and any reacquisition or repurchase rights held by the Company with respect to such Stock Awards shall lapse (contingent upon the effectiveness of the Corporate Transaction). If the acquisition agreement provides a
procedure for the net exercise of Options at the closing of the Corporate Transaction, then the Optionholder who does not elect to exercise prior to closing shall be deemed to have agreed to the net exercise (including the deduction of the aggregate
exercise price and applicable withholding taxes) and shall be deemed to have agreed to the terms and conditions of the acquisition agreement approved by the stockholders of the Company as if the Optionholder were a stockholder immediately prior to
the effective time of the Corporate Transaction including without limitation any escrow and indemnity provisions and appointment of a stockholders’ representative. No vested Restricted Stock Unit Award shall terminate pursuant to this
Section 10(c)(ii) without being settled by delivery of shares of Common Stock, their cash equivalent, any combination thereof, or in any other form of consideration, as determined by the Board, prior to the effective time of the Corporate
Transaction. 
 (iii) Stock Awards Held by Persons other than Current Participants. In the event of a
Corporate Transaction in which the surviving corporation or acquiring corporation (or its parent company) does not assume or continue any or all outstanding Stock Awards or substitute similar stock awards for such outstanding Stock Awards, then with
respect to Stock Awards that have not been assumed, continued or substituted and that are held by persons other than Current Participants, the vesting of such Stock Awards (and, if applicable, the time at which such Stock Award may be exercised)
shall not be accelerated and such Stock Awards (other than a Stock Award consisting of vested and outstanding shares of Common Stock not subject to the Company’s right of repurchase) shall terminate if not exercised (if applicable) prior to the
effective time of the Corporate Transaction; provided, however, that any reacquisition or repurchase rights held by the Company with respect to such Stock Awards shall not terminate and may continue to be exercised
notwithstanding the Corporate Transaction. No vested Restricted Stock Unit Award shall terminate pursuant to this Section 10(c)(iii) without being settled by delivery of shares of Common Stock, their cash equivalent, any combination thereof, or
in any other form of consideration, as determined by the Board, prior to the effective time of the Corporate Transaction. 

(iv) Payment for Stock Awards in Lieu of Exercise. Notwithstanding the foregoing, in the event a Stock Award will
terminate if not exercised prior to the effective time of a Corporate Transaction, the Board may provide, in its sole discretion, that the holder of such Stock Award may not exercise such Stock Award but will receive a payment, in such form as may
be determined by the Board, equal in value to the excess, if any, of (A) the value of the  

  
 23. 

 
property the holder of the Stock Award would have received upon the exercise of the Stock Award, over (B) any exercise price payable by such holder in connection with such exercise. 

(v) Change in Control. A Stock Award may be subject to 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 shall occur.  
 11. TERMINATION OR SUSPENSION OF
THE PLAN. 
 (a) Plan Term. Unless sooner terminated by the Board pursuant to
Section 3, the Plan automatically shall terminate on the day before the tenth (10th) anniversary of the date the Plan is adopted by the Board or approved by the stockholders of the Company, whichever is earlier. No Stock Awards may be
granted under the Plan while the Plan is suspended or after it is terminated.  
 (b) No Impairment of Rights.
Suspension or termination of the Plan shall not impair rights and obligations under any Stock Award granted while the Plan is in effect except with the written consent of the affected Participant. 

12. EFFECTIVE DATE OF PLAN. 

This Plan shall become effective on the Effective Date. 

13. CHOICE OF LAW. 

The law of the State of California shall govern all questions concerning the construction, validity and interpretation of this
Plan, without regard to such state’s conflict of laws rules. 

  
 24. 

 TOCAGEN INC. 

OPTION GRANT NOTICE 

(2009 EQUITY INCENTIVE PLAN) 

Tocagen Inc. (the “Company”), pursuant to its 2009 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 herein and in the
Option Agreement, the Plan, the Notice of Exercise and the Voting Agreement, all of which are attached hereto and incorporated herein in their entirety. 
  

			
	Optionholder:	  	  

	Date of Grant:	  	  

	Vesting Commencement Date:	  	  

	Number of Shares Subject to Option:	  	  

	Exercise Price (Per Share):	  	  

	Total Exercise Price:	  	  

	Expiration Date:	  	  

  

							
	Type of Grant:	 	☐	  	Incentive Stock Option1	  	☒      Nonstatutory Stock Option
				
	Exercise Schedule:	 	☒	  	Same as Vesting Schedule	  	
		
	Vesting Schedule:	 	1/4th of the shares vest one year after the Vesting Commencement Date.
		
		 	1/48th of the shares vest monthly thereafter over the next three years.
		
		 	1/4th of the shares shall vest (or all remaining unvested shares at such time, whichever is less) in the event of a Change in Control (as defined in the
Plan).
		
		 	1/4th of the shares shall vest (or all remaining unvested shares at such time, whichever is less) in the event of the death or Disability (as defined in the Plan)
of the Optionholder.
		
	Payment:	 	By one or a combination of the following items (described in the Option Agreement):
			
		 	☒	  	By cash or check
			
		 	☒	  	By 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
			
		 	☒	  	By net exercise if the Company has established a procedure for net exercise at the time of such exercise

 Additional Terms/Acknowledgements: The undersigned Optionholder acknowledges receipt of, and
understands and agrees to, this Stock Option Grant Notice, the Option Agreement, the Plan and the Voting Agreement. Optionholder further acknowledges that as of the Date of Grant, this Stock Option Grant Notice, the Option Agreement, the Plan and
the Voting Agreement set forth the entire understanding between Optionholder and the Company regarding the acquisition of stock in the Company and supersede all prior oral and written agreements on that subject with the exception of (i) options
previously granted and delivered to Optionholder under the Plan, and (ii) the following agreements only: 
  

			
	OTHER AGREEMENTS:	  	  

		  	  

 [Signatures on Following Page] 
  

 

	1	 If this is an Incentive Stock Option, it (plus other
outstanding incentive stock options granted to Optionholder by the Company) 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. 

									
	TOCAGEN INC.	 		 	OPTIONHOLDER:
				
	 By:
	 	  
	 		 	  

		 	Signature	 		 		 	Signature
	 Title:
	 	  
	 		 	 Date:
	 	  

	 Date:
	 	  
	 		 		 	

 ATTACHMENTS: Option Agreement, 2009 Equity Incentive Plan and Notice of
Exercise, Voting Agreement 

 ATTACHMENT I 

TOCAGEN INC. 

2009 EQUITY INCENTIVE PLAN 

OPTION AGREEMENT 

(INCENTIVE STOCK OPTION OR NONSTATUTORY STOCK
OPTION) 
 Pursuant to your Option Grant Notice (“Grant Notice”) and this Option
Agreement, Tocagen Inc. (the “Company”) has granted you an option under its 2009 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. Defined terms not explicitly defined in this Option Agreement but defined in the Plan shall have the same definitions as in the Plan. 

The details of your option are as follows: 

1. VESTING. Subject to the limitations contained herein, your option will vest as provided in your Grant
Notice, provided that 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 referenced in your Grant Notice may be
adjusted from time to time for Capitalization Adjustments. 
 3. EXERCISE PRIOR
TO VESTING (“EARLY EXERCISE”). If permitted in your Grant Notice (i.e., the “Exercise Schedule” indicates that “Early Exercise” of your option is
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
nonvested portion of your option; provided, however, that: 
 (a) a partial exercise of your option shall 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 shall 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 shall 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 time 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) shall be treated as
Nonstatutory Stock Options. 
 4. EXERCISE RESTRICTION FOR
NON-EXEMPT EMPLOYEES. In the event that you are an Employee eligible for overtime compensation under the Fair Labor Standards Act of 1938, as amended (i.e., a “Non-Exempt
Employee”), you may not exercise your option until you have completed at least six (6) months of Continuous Service measured from the Date of Grant specified in your Grant Notice, notwithstanding any other provision of your option.

 5. METHOD OF PAYMENT. Payment of the exercise price is due in full
upon exercise of all or any part of your option. You may elect to make payment of the exercise price in cash or by check or in any other manner permitted by your Grant Notice, which may include one or more of the following: 

(a) Bank draft or money order payable to the Company. 

(b) Provided that at the time of exercise the Common Stock is publicly traded and quoted regularly in The Wall
Street Journal, 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. 
 (c) Provided
that at the time of exercise the Common Stock is publicly traded and quoted regularly in The Wall Street Journal, 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. Notwithstanding the foregoing, you may not exercise your option by tender to the Company of Common Stock to
the extent such tender would violate the provisions of any law, regulation or agreement restricting the redemption of the Company’s stock. 

(d) 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; provided, however, that the Company shall accept a cash or other payment from you 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; provided further, however, that shares of Common Stock will no longer be outstanding under your
option and will not be exercisable thereafter to the extent that (1) shares are used to pay the exercise price pursuant to the “net exercise,” (2) shares are delivered to you as a result of such exercise, and (3) shares are
withheld to satisfy tax withholding obligations. 
 6. WHOLE SHARES. You may exercise
your option only for whole shares of Common Stock. 
 7. SECURITIES LAW
COMPLIANCE. Notwithstanding anything to the contrary contained herein, you may not exercise your option unless the shares of Common Stock issuable 

 
upon such exercise are then registered under the Securities Act or, if such shares of Common Stock are not then so registered, the Company has determined that such exercise and issuance would be
exempt from the registration requirements of the Securities Act. The exercise of your option also must comply with 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. 
 8. TERM. You may not
exercise your option before the commencement or after the expiration of its term. The term of your option commences on the Date of Grant and expires 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 or your
Disability or death; provided, however, that (i) 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, your option shall not expire until the
earlier of the Expiration Date or until it shall have been exercisable for an aggregate period of three (3) months after the termination of your Continuous Service and (ii) if (x) you are a Non-Exempt Employee, (y) you terminate
your Continuous Service within six (6) months after the Date of Grant specified in your Grant Notice, and (z) you have vested in a portion of your option at the time of your termination of Continuous Service, your option shall not expire
until the earlier of (A) the later of the date that is seven (7) months after the Date of Grant specified in your Grant Notice or the date that is three (3) months after the termination of your Continuous Service or (B) the
Expiration Date; 
 (c) twelve (12) months after the termination of your Continuous Service due to your
Disability; 
 (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 of your option 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 your permanent and total disability, as defined in Section 22(e) of the Code. (The definition of disability in Section 22(e) of the Code is different from the definition of
Disability under the Plan). 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 delivering a Notice of Exercise (in a form designated by the Company) together with the exercise price to the Secretary of the Company, or to such other person as the Company may designate, during regular business hours,
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 your option grant or within one
(1) year after such shares of Common Stock are transferred upon exercise of your option. 
 (d)
By exercising your option, you agree that you shall 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 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 (the
“Lock-Up Period”); (or such longer period, not to exceed thirty-four (34) days after the expiration of the 180-day period, as the underwriters or the Company shall request in order to facilitate compliance
with NASD Rule 2711); provided, however, that nothing contained in this Section 9(d) shall 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 and/or the managing underwriter which are consistent with the foregoing or which 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. The underwriters of the Company’s stock are intended third party beneficiaries of this Section 9(d) and shall have the
right, power and authority to enforce the provisions hereof as though they were a party hereto. For the avoidance of doubt, if you sell any Common Stock either (a) on the open market after the Company’s initial public offering under an
effective registration statement filed under the Securities Act or (b) pursuant to Rule 144 under the Securities Act, then, provided such sale otherwise complies with the terms of this Option Agreement, the shares of Common Stock so sold
by you shall cease to be subject to the provisions of this Section 9(d). 
 10.
TRANSFERABILITY.  
 (a) Subject to Section 10(b), in addition to any other limitation
on transfer created by applicable securities laws, you agree that you will not assign, hypothecate, donate,  

 
encumber or otherwise dispose of any interest in any portion of your option. After you have exercised your option, you agree that you will not assign, hypothecate, donate, encumber or
otherwise dispose of any interest in any Common Stock issued upon exercise except in compliance with the provisions herein and applicable securities laws. Furthermore, such Common Stock shall be subject to any right of first refusal in favor of the
Company or its assignees that may be contained in the Company’s Bylaws. You hereby further acknowledge that you may be required to hold such Common Stock issued upon exercise hereunder indefinitely. During the period of time during which you
hold such Common Stock, the value of the Common Stock may increase or decrease, and any risk associated with such Common Stock and such fluctuation in value shall be borne by you. Additionally, if your option is an Incentive Stock Option, the
Board may permit you to transfer your option only to the extent permitted by Sections 421, 422 and 424 of the Code and the regulations and other guidance thereunder. To the extent otherwise permitted pursuant to this Option Agreement, if your option
is an Incentive Stock Option and you transfer the option pursuant to a domestic relations order, such option shall be deemed to be a Nonstatutory Stock Option as a result of such transfer.  

(b) Notwithstanding anything to the contrary contained elsewhere in this Option Agreement, the transfer of any or all
of the Common Stock issued upon exercise of your option during your lifetime or on your death by will or intestacy to your spouse, child, father, mother, brother, sister, father-in-law, mother-in-law, brother-in-law, sister-in-law, grandfather,
grandmother, grandchild, cousin, aunt, uncle, niece, nephew, stepchild, other bona fide done (whether or not related to you), or to a bona fide charitable organization where the transfer to such organization would qualify for an exemption from
registration under the Securities Act, or to a trust, partnership, limited liability corporation or other similar estate planning vehicle for the benefit of you or any such person or organization, shall be exempt from the provisions of this
Section 10; provided that, in each such case, the transferee agrees in writing to receive and hold the Common Stock so transferred subject to all of the provisions of this Option Agreement, including but not limited to this Section 10, and
there shall be no further transfer of such Common Stock except in accordance with the terms of this Section 10. 

(c) Notwithstanding anything to the contrary contained elsewhere in this Option Agreement, for so long as the Common
Stock issued upon exercise of your option is subject to any right of first refusal in favor of the Company or its assignees that may be contained in the Company’s Bylaws, you agree that you shall not assign, hypothecate, donate, encumber or
otherwise dispose of any interest in such Common Stock to any entity that the Company’s Board determines in good faith to be a competitor of the Company. If you propose to assign, hypothecate, donate, encumber or otherwise dispose of any
interest in such Common Stock to any entity that is engaged in the research, development or commercialization of pharmaceutical products, you shall first give written notice thereof to the Company identifying such entity in order that the
Company’s Board may make such determination. Such determination of the Board shall be final and binding upon you. 

(d) Notwithstanding the foregoing, you may, by delivering written notice to the Company, in a form provided by or
otherwise satisfactory to the Company, designate a third party who, in the event of your death, shall thereafter be entitled to exercise your option and receive the Common Stock or other consideration resulting from an Option exercise. In the 

 
absence of such designation, the executor or administrator of your estate shall be entitled to exercise the Option and receive the Common Stock or other consideration resulting from an Option
exercise in accordance with the terms of this Option Agreement. 
 11. RIGHT OF
FIRST REFUSAL. Shares of Common Stock that you acquire upon exercise of your option are subject to any right of first refusal that may be described in the Company’s bylaws in effect at such time the Company
elects to exercise its right; provided, however, that if your option is an Incentive Stock Option and the right of first refusal described in the Company’s bylaws in effect at the time the Company elects to exercise its right is more
beneficial to you than the right of first refusal described in the Company’s bylaws on the Date of Grant, then the right of first refusal described in the Company’s bylaws on the Date of Grant shall apply. The Company’s right of first
refusal shall expire on the Listing Date. For purposes of this Agreement, Listing Date shall mean the first date upon which any security of the Company is listed (or approved for listing) upon notice of issuance on a national securities exchange or
traded on any established market. 
 12. RIGHT OF REPURCHASE. To the
extent provided in the Company’s bylaws in effect at such time the Company elects to exercise its right, the Company shall have the right to repurchase all or any part of the shares of Common Stock you acquire pursuant to the exercise of your
option. 
 13. OPTION NOT A SERVICE
CONTRACT. Your option is not an employment or service contract, and nothing in your option shall 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 shall 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. 
 14. WITHHOLDING
OBLIGATIONS. 
 (a) At the time you exercise your option, in whole or in part, or 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 “cashless exercise” pursuant to a
program developed under Regulation T as promulgated by the Federal Reserve Board to the extent permitted by the Company), any sums required to satisfy the federal, state, local and foreign tax withholding obligations of the Company or an Affiliate,
if any, which arise in connection with the exercise of your option. 
 (b) Upon your request and subject to
approval by the Company, in its sole discretion, 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
variable award accounting). 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 shall 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 unless such obligations are satisfied. 

15. NOTICES. Any notices provided for in your option or the Plan shall be given in writing and shall 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.

 16. 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. In
the event of any conflict between the provisions of your option and those of the Plan, the provisions of the Plan shall control. 

17. VOTING AGREEMENT. As a condition to the entering into of this Option Agreement by the
Company and effective upon your entering into this Option Agreement, without any further action on your part or the Company’s part, you and the Company hereby agree that you are a party to that certain Voting Agreement, dated December 20,
2007, between certain holders of Common Stock of the Company (the “Voting Agreement”) pursuant to which such holders of Common Stock grant to Harry Gruber, M.D. the power and authority to vote all shares of Common Stock
represented by the Voting Agreement on all matters for which a vote of holders of Common Stock of the Company is required or requested as set forth in the Voting Agreement. You also agree that, upon request, you will deliver to the Company a
counterpart signature page to the Voting Agreement, duly executed by you. You agree that you have had the opportunity to review and to seek the advise of your legal counsel with respect to the Voting Agreement. 

 ATTACHMENT II 

2009 EQUITY INCENTIVE PLAN 

 ATTACHMENT III 

NOTICE OF EXERCISE 

TOCAGEN INC. 

Date of Exercise:
                     
 Ladies
and Gentlemen: 
 This constitutes notice under my stock option that I elect to purchase the number of 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:	 	 $            

		
	Value of payment delivered herewith:	 	 $            

	  
 Form of payment:
	 	  
 ☐
	 	  
 By cash or check

 
	 	
		 	 ☐
	 	 By 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 traded2

 

		 	 ☐
	 	By net exercise if the Company has established a procedure for net exercise at the time of such exercise

 By this exercise, I agree (i) to provide such additional documents as you may require
pursuant to the terms of the 2009 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 of 

 

	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.

 
Common Stock 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 of Common Stock are
issued upon exercise of this option. 
 I acknowledge that I am aware of the Company’s business affairs and financial
condition and have acquired sufficient information about the Company to reach an informed and knowledgeable decision to acquire the shares of Common Stock of the Company listed above (the “Shares”). I am purchasing the Shares
for investment for my own account only and not with a view to, or for resale in connection with, any “distribution” thereof within the meaning of the Securities Act. 

I further acknowledge that the Shares have not been registered under the Securities Act by reason of a specific exemption
therefrom, which exemption depends upon, among other things, the bona fide nature of my investment intent as expressed herein. 

I further acknowledge that the Shares must be held indefinitely unless the Shares are subsequently registered under the
Securities Act or an exemption from such registration is available. I further acknowledge that the Company is under no obligation to register the Shares. I understand that the certificate evidencing the Shares will be imprinted with a legend or
legends which prohibit the transfer of the Shares unless the Shares are registered or such registration is not required in the opinion of counsel for the Company. 

I am familiar with the provisions of Rule 144, under the Securities Act, as in effect from time to time, which, in substance,
permit limited public resale of “restricted securities” acquired, directly or indirectly, from the issuer thereof (or from an affiliate of such issuer), in a non-public offering subject to the satisfaction of certain conditions. The Shares
may be resold by me in certain limited circumstances subject to the provisions of Rule 144, which requires, among other things: (i) the availability of certain public information about the Company and (ii) the resale occurring following
the required holding period under Rule 144 after I have purchased, and made full payment for (within the meaning of Rule 144), the securities to be sold. 

I further understand that at the time I wish to sell the Shares there may be no public market upon which to make such a sale,
and that, even if such a public market then exists, the Company may not be satisfying the current public information requirements of Rule 144, and that, in such event, I would be precluded from selling the Shares under Rule 144 even if the minimum
holding period requirement had been satisfied. 
 I further warrant and represent that I have either (i) preexisting
personal or business relationships, with the Company or any of its officers, directors or controlling persons, or (ii) the capacity to protect my own interests in connection with the purchase of the Shares by virtue of the business or financial
expertise of myself or of my professional advisors who are unaffiliated with and who are not compensated by the Company or any of its affiliates, directly or indirectly. 

I further acknowledge that I will not be able to resell the Shares for at least ninety (90) days after the stock
of the Company becomes publicly traded (i.e., subject to the reporting requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934) under Rule 701 and that more restrictive conditions apply to affiliates of the Company
under Rule 144. 

 I further acknowledge that all certificates representing any of the Shares
subject to the provisions of this Option shall have endorsed thereon appropriate legends reflecting the foregoing limitations, as well as any legends reflecting restrictions pursuant to the Company’s Certificate of Incorporation, Bylaws and/or
applicable securities laws. 
 I further agree that I will not sell, dispose of, transfer, make any short sale of,
grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale, any Shares or other securities of the Company held by me, 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 (the “Lock-Up Period”); (or such longer period, not to exceed thirty-four (34) days after the expiration of the
180-day period, as the underwriters or the Company shall request in order to facilitate compliance with NASD Rule 2711); provided, however, that nothing contained in this paragraph shall prevent the exercise of a repurchase option, if any, in
favor of the Company during the Lock-Up Period. I further agree to execute and deliver such other agreements as may be reasonably requested by the Company and/or the managing underwriter which are consistent with the foregoing or which are necessary
to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to my Shares until the end of such period. I agree that the underwriters of the Company’s stock are
intended third party beneficiaries of this paragraph and shall have the right, power and authority to enforce the provisions hereof as though they were a party hereto.  

I further acknowledge that, effective upon my entering into the Stock Option Agreement with the Company pursuant to which I am
now exercising my stock option, I became a party to, and am presently and hereafter bound by, that certain Voting Agreement pursuant to which I have granted power and authority to vote all of the Shares to Harry Gruber, M.D. on all matters for which
a vote of holders of the Common Stock of the Company is required or requested as set forth in such Voting Agreement. I also agree that, upon request, I will deliver to the Company a counterpart signature page to the Voting Agreement, duly executed
by me. I agree that I have had the opportunity to review and to seek the advise of my independent legal counsel with respect to such Voting Agreement. 
  

			
	Very truly yours,
	
	  

	Name:	 	  

	Date:	 	  

 TOCAGEN INC. 

OPTION GRANT NOTICE 

(2009 EQUITY INCENTIVE PLAN) 

Tocagen Inc. (the “Company”), pursuant to its 2009 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 herein and in the
Option Agreement, the Plan, the Notice of Exercise and the Voting Agreement, all of which are attached hereto and incorporated herein in their entirety. 
  

			
	Optionholder:	  	  

	Date of Grant:	  	  

	Vesting Commencement Date:	  	  

	Number of Shares Subject to Option:	  	  

	Exercise Price (Per Share):	  	  

	Total Exercise Price:	  	  

	Expiration Date:	  	  

  

							
	Type of Grant:	 	☐	  	Incentive Stock Option1	  	☒      Nonstatutory Stock Option
				
	Exercise Schedule:	 	☒	  	Same as Vesting Schedule	  	
		
	Vesting Schedule:	 	1/4th of the shares vest one year after the Vesting Commencement Date.
		
		 	1/48th of the shares vest monthly thereafter over the next three years.
		
		 	100% of the shares shall vest (or all remaining unvested shares at such time, whichever is less) in the event of a Change in Control (as defined in the Plan).
		
	Payment:	 	By one or a combination of the following items (described in the Option Agreement):
			
		 	☒	  	By cash or check
			
		 	☒	  	By 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
			
		 	☒	  	By net exercise if the Company has established a procedure for net exercise at the time of such exercise

 Additional Terms/Acknowledgements: The undersigned Optionholder acknowledges receipt of, and
understands and agrees to, this Stock Option Grant Notice, the Option Agreement, the Plan and the Voting Agreement. Optionholder further acknowledges that as of the Date of Grant, this Stock Option Grant Notice, the Option Agreement, the Plan and
the Voting Agreement set forth the entire understanding between Optionholder and the Company regarding the acquisition of stock in the Company and supersede all prior oral and written agreements on that subject with the exception of (i) options
previously granted and delivered to Optionholder under the Plan, and (ii) the following agreements only: 
  

			
	OTHER AGREEMENTS:	  	  

		  	  

 [Signatures on Following Page] 
  

 

	1 	 If this is an Incentive Stock Option, it (plus other outstanding incentive stock options granted to
Optionholder by the Company) 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. 

									
	TOCAGEN INC.	 		 	OPTIONHOLDER:
				
	 By:
	 	  
	 		 	  

		 	Signature	 		 		 	Signature
	 Title:
	 	  
	 		 	 Date:
	 	  

	 Date:
	 	  
	 		 		 	

 ATTACHMENTS: Option Agreement, 2009 Equity Incentive Plan and Notice of Exercise, Voting
Agreement 

 ATTACHMENT I 

TOCAGEN INC. 

2009 EQUITY INCENTIVE PLAN 

OPTION AGREEMENT 

(INCENTIVE STOCK OPTION OR NONSTATUTORY STOCK
OPTION) 
 Pursuant to your Option Grant Notice (“Grant Notice”) and this Option
Agreement, Tocagen Inc. (the “Company”) has granted you an option under its 2009 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. Defined terms not explicitly defined in this Option Agreement but defined in the Plan shall have the same definitions as in the Plan. 

The details of your option are as follows: 

1. VESTING. Subject to the limitations contained herein, your option will vest as provided in your Grant
Notice, provided that 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 referenced in your Grant Notice may be
adjusted from time to time for Capitalization Adjustments. 
 3. EXERCISE PRIOR
TO VESTING (“EARLY EXERCISE”). If permitted in your Grant Notice (i.e., the “Exercise Schedule” indicates that “Early Exercise” of your option is
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
nonvested portion of your option; provided, however, that: 
 (a) a partial exercise of your option shall 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 shall 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 shall 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 time 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) shall be treated as
Nonstatutory Stock Options. 
 4. EXERCISE RESTRICTION FOR
NON-EXEMPT EMPLOYEES. In the event that you are an Employee eligible for overtime compensation under the Fair Labor Standards Act of 1938, as amended (i.e., a “Non-Exempt
Employee”), you may not exercise your option until you have completed at least six (6) months of Continuous Service measured from the Date of Grant specified in your Grant Notice, notwithstanding any other provision of your option.

 5. METHOD OF PAYMENT. Payment of the
exercise price is due in full upon exercise of all or any part of your option. You may elect to make payment of the exercise price in cash or by check or in any other manner permitted by your Grant Notice, which may include one or more
of the following: 
 (a) Bank draft or money order payable to the Company. 

(b) Provided that at the time of exercise the Common Stock is publicly traded and quoted regularly in
The Wall Street Journal, 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. 

(c) Provided that at the time of exercise the Common Stock is publicly traded and quoted regularly in
The Wall Street Journal, 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. Notwithstanding the foregoing, you may not exercise your option by tender to the Company of Common Stock to the extent such tender would violate the provisions of any law, regulation or agreement
restricting the redemption of the Company’s stock.  
 (d) 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;
provided, however, that the Company shall accept a cash or other payment from you 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; provided
further, however, that shares of Common Stock will no longer be outstanding under your option and will not be exercisable thereafter to the extent that (1) shares are used to pay the exercise price pursuant to the “net exercise,”
(2) shares are delivered to you as a result of such exercise, and (3) shares are withheld to satisfy tax withholding obligations. 

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

7. SECURITIES LAW COMPLIANCE. Notwithstanding anything to the contrary
contained herein, you may not exercise your option unless the shares of Common Stock issuable 

 
upon such exercise are then registered under the Securities Act or, if such shares of Common Stock are not then so registered, the Company has determined that such exercise and issuance would be
exempt from the registration requirements of the Securities Act. The exercise of your option also must comply with 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. 
 8. TERM. You may not
exercise your option before the commencement or after the expiration of its term. The term of your option commences on the Date of Grant and expires 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 or your
Disability or death; provided, however, that (i) 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, your option shall not expire until the
earlier of the Expiration Date or until it shall have been exercisable for an aggregate period of three (3) months after the termination of your Continuous Service and (ii) if (x) you are a Non-Exempt Employee, (y) you terminate
your Continuous Service within six (6) months after the Date of Grant specified in your Grant Notice, and (z) you have vested in a portion of your option at the time of your termination of Continuous Service, your option shall not expire
until the earlier of (A) the later of the date that is seven (7) months after the Date of Grant specified in your Grant Notice or the date that is three (3) months after the termination of your Continuous Service or (B) the
Expiration Date; 
 (c) twelve (12) months after the termination of your Continuous Service due to your
Disability; 
 (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 of your option 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 your permanent and total disability, as defined in Section 22(e) of the Code. (The definition of disability in Section 22(e) of the Code is different from the definition of
Disability under the Plan). 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 delivering a Notice of Exercise (in a form designated by the Company) together with the exercise price to the Secretary of the Company, or to such other person as the Company may designate, during regular business hours,
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 your option grant or within one
(1) year after such shares of Common Stock are transferred upon exercise of your option. 
 (d) By exercising
your option, you agree that you shall 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 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 (the “Lock-Up Period”); (or such
longer period, not to exceed thirty-four (34) days after the expiration of the 180-day period, as the underwriters or the Company shall request in order to facilitate compliance with NASD Rule 2711); provided, however, that nothing
contained in this Section 9(d) shall 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 and/or the managing underwriter which are consistent with the foregoing or which 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. The underwriters of the Company’s stock are intended third party beneficiaries of this Section 9(d) and shall have the right, power and authority to enforce the provisions hereof as
though they were a party hereto. For the avoidance of doubt, if you sell any Common Stock either (a) on the open market after the Company’s initial public offering under an effective registration statement filed under the Securities Act or
(b) pursuant to Rule 144 under the Securities Act, then, provided such sale otherwise complies with the terms of this Option Agreement, the shares of Common Stock so sold by you shall cease to be subject to the provisions of this Section
9(d). 
 10. TRANSFERABILITY.  

(a) Subject to Section 10(b), in addition to any other limitation on transfer created by applicable securities
laws, you agree that you will not assign, hypothecate, donate, 

 
encumber or otherwise dispose of any interest in any portion of your option. After you have exercised your option, you agree that you will not assign, hypothecate, donate, encumber or otherwise
dispose of any interest in any Common Stock issued upon exercise except in compliance with the provisions herein and applicable securities laws. Furthermore, such Common Stock shall be subject to any right of first refusal in favor of the Company or
its assignees that may be contained in the Company’s Bylaws. You hereby further acknowledge that you may be required to hold such Common Stock issued upon exercise hereunder indefinitely. During the period of time during which you hold such
Common Stock, the value of the Common Stock may increase or decrease, and any risk associated with such Common Stock and such fluctuation in value shall be borne by you. Additionally, if your option is an Incentive Stock Option, the Board may
permit you to transfer your option only to the extent permitted by Sections 421, 422 and 424 of the Code and the regulations and other guidance thereunder. To the extent otherwise permitted pursuant to this Option Agreement, if your option is an
Incentive Stock Option and you transfer the option pursuant to a domestic relations order, such option shall be deemed to be a Nonstatutory Stock Option as a result of such transfer. 

(b) Notwithstanding anything to the contrary contained elsewhere in this Option Agreement, the transfer of any or all
of the Common Stock issued upon exercise of your option during your lifetime or on your death by will or intestacy to your spouse, child, father, mother, brother, sister, father-in-law, mother-in-law, brother-in-law, sister-in-law, grandfather,
grandmother, grandchild, cousin, aunt, uncle, niece, nephew, stepchild, other bona fide done (whether or not related to you), or to a bona fide charitable organization where the transfer to such organization would qualify for an exemption from
registration under the Securities Act, or to a trust, partnership, limited liability corporation or other similar estate planning vehicle for the benefit of you or any such person or organization, shall be exempt from the provisions of this
Section 10; provided that, in each such case, the transferee agrees in writing to receive and hold the Common Stock so transferred subject to all of the provisions of this Option Agreement, including but not limited to this Section 10, and
there shall be no further transfer of such Common Stock except in accordance with the terms of this Section 10. 

(c) Notwithstanding anything to the contrary contained elsewhere in this Option Agreement, for so long as the Common
Stock issued upon exercise of your option is subject to any right of first refusal in favor of the Company or its assignees that may be contained in the Company’s Bylaws, you agree that you shall not assign, hypothecate, donate, encumber or
otherwise dispose of any interest in such Common Stock to any entity that the Company’s Board determines in good faith to be a competitor of the Company. If you propose to assign, hypothecate, donate, encumber or otherwise dispose of any
interest in such Common Stock to any entity that is engaged in the research, development or commercialization of pharmaceutical products, you shall first give written notice thereof to the Company identifying such entity in order that the
Company’s Board may make such determination. Such determination of the Board shall be final and binding upon you. 

(d) Notwithstanding the foregoing, you may, by delivering written notice to the Company, in a form provided by or
otherwise satisfactory to the Company, designate a third party who, in the event of your death, shall thereafter be entitled to exercise your option and receive the Common Stock or other consideration resulting from an Option exercise. In the

 
absence of such designation, the executor or administrator of your estate shall be entitled to exercise the Option and receive the Common Stock or other consideration resulting from an Option
exercise in accordance with the terms of this Option Agreement. 
 11. RIGHT OF
FIRST REFUSAL. Shares of Common Stock that you acquire upon exercise of your option are subject to any right of first refusal that may be described in the Company’s bylaws in effect at such time the Company
elects to exercise its right; provided, however, that if your option is an Incentive Stock Option and the right of first refusal described in the Company’s bylaws in effect at the time the Company elects to exercise its right is more
beneficial to you than the right of first refusal described in the Company’s bylaws on the Date of Grant, then the right of first refusal described in the Company’s bylaws on the Date of Grant shall apply. The Company’s right of first
refusal shall expire on the Listing Date. For purposes of this Agreement, Listing Date shall mean the first date upon which any security of the Company is listed (or approved for listing) upon notice of issuance on a national securities exchange or
traded on any established market. 
 12. RIGHT OF REPURCHASE. To the
extent provided in the Company’s bylaws in effect at such time the Company elects to exercise its right, the Company shall have the right to repurchase all or any part of the shares of Common Stock you acquire pursuant to the exercise of your
option. 
 13. OPTION NOT A SERVICE
CONTRACT. Your option is not an employment or service contract, and nothing in your option shall 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 shall 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. 
 14. WITHHOLDING
OBLIGATIONS. 
 (a) At the time you exercise your option, in whole or in part, or 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 “cashless exercise” pursuant to a
program developed under Regulation T as promulgated by the Federal Reserve Board to the extent permitted by the Company), any sums required to satisfy the federal, state, local and foreign tax withholding obligations of the Company or an Affiliate,
if any, which arise in connection with the exercise of your option. 
 (b) Upon your request and subject to approval
by the Company, in its sole discretion, 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 variable
award accounting). 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 shall 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 unless such obligations are satisfied. 

15. NOTICES. Any notices provided for in your option or the Plan shall be given in writing and shall 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.

 16. 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. In
the event of any conflict between the provisions of your option and those of the Plan, the provisions of the Plan shall control. 

17. VOTING AGREEMENT. As a condition to the entering into of this Option Agreement by the
Company and effective upon your entering into this Option Agreement, without any further action on your part or the Company’s part, you and the Company hereby agree that you are a party to that certain Voting Agreement, dated December 20,
2007, between certain holders of Common Stock of the Company (the “Voting Agreement”) pursuant to which such holders of Common Stock grant to Harry Gruber, M.D. the power and authority to vote all shares of Common Stock
represented by the Voting Agreement on all matters for which a vote of holders of Common Stock of the Company is required or requested as set forth in the Voting Agreement. You also agree that, upon request, you will deliver to the Company a
counterpart signature page to the Voting Agreement, duly executed by you. You agree that you have had the opportunity to review and to seek the advise of your legal counsel with respect to the Voting Agreement. 

 ATTACHMENT II 

2009 EQUITY INCENTIVE PLAN 

 ATTACHMENT III 

NOTICE OF EXERCISE 

TOCAGEN INC. 

Date of Exercise:                     

 Ladies and Gentlemen: 

This constitutes notice under my stock option that I elect to purchase the number of 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:	 	 $            

		
	Value of payment delivered herewith:	 	 $            

	  
 Form of payment:
	 	  
 ☐
	 	  
 By cash or check

 
	 	
		 	 ☐
	 	 By 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 traded2

 

		 	 ☐
	 	By net exercise if the Company has established a procedure for net exercise at the time of such exercise

 By this exercise, I agree (i) to provide such additional documents as you may require
pursuant to the terms of the 2009 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 of 

 

	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.

 
Common Stock 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 of Common Stock are
issued upon exercise of this option. 
 I acknowledge that I am aware of the Company’s business affairs and financial
condition and have acquired sufficient information about the Company to reach an informed and knowledgeable decision to acquire the shares of Common Stock of the Company listed above (the “Shares”). I am purchasing the Shares
for investment for my own account only and not with a view to, or for resale in connection with, any “distribution” thereof within the meaning of the Securities Act. 

I further acknowledge that the Shares have not been registered under the Securities Act by reason of a specific exemption
therefrom, which exemption depends upon, among other things, the bona fide nature of my investment intent as expressed herein. 

I further acknowledge that the Shares must be held indefinitely unless the Shares are subsequently registered under the
Securities Act or an exemption from such registration is available. I further acknowledge that the Company is under no obligation to register the Shares. I understand that the certificate evidencing the Shares will be imprinted with a legend or
legends which prohibit the transfer of the Shares unless the Shares are registered or such registration is not required in the opinion of counsel for the Company. 

I am familiar with the provisions of Rule 144, under the Securities Act, as in effect from time to time, which, in substance,
permit limited public resale of “restricted securities” acquired, directly or indirectly, from the issuer thereof (or from an affiliate of such issuer), in a non-public offering subject to the satisfaction of certain conditions. The Shares
may be resold by me in certain limited circumstances subject to the provisions of Rule 144, which requires, among other things: (i) the availability of certain public information about the Company and (ii) the resale occurring following
the required holding period under Rule 144 after I have purchased, and made full payment for (within the meaning of Rule 144), the securities to be sold. 

I further understand that at the time I wish to sell the Shares there may be no public market upon which to make such a sale,
and that, even if such a public market then exists, the Company may not be satisfying the current public information requirements of Rule 144, and that, in such event, I would be precluded from selling the Shares under Rule 144 even if the minimum
holding period requirement had been satisfied. 
 I further warrant and represent that I have either (i) preexisting
personal or business relationships, with the Company or any of its officers, directors or controlling persons, or (ii) the capacity to protect my own interests in connection with the purchase of the Shares by virtue of the business or financial
expertise of myself or of my professional advisors who are unaffiliated with and who are not compensated by the Company or any of its affiliates, directly or indirectly. 

I further acknowledge that I will not be able to resell the Shares for at least ninety (90) days after the stock
of the Company becomes publicly traded (i.e., subject to the reporting requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934) under Rule 701 and that more restrictive conditions apply to affiliates of the Company
under Rule 144. 

 I further acknowledge that all certificates representing any of the Shares
subject to the provisions of this Option shall have endorsed thereon appropriate legends reflecting the foregoing limitations, as well as any legends reflecting restrictions pursuant to the Company’s Certificate of Incorporation, Bylaws and/or
applicable securities laws. 
 I further agree that I will not sell, dispose of, transfer, make any short sale of,
grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale, any Shares or other securities of the Company held by me, 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 (the “Lock-Up Period”); (or such longer period, not to exceed thirty-four (34) days after the expiration of the
180-day period, as the underwriters or the Company shall request in order to facilitate compliance with NASD Rule 2711); provided, however, that nothing contained in this paragraph shall prevent the exercise of a repurchase option, if any, in
favor of the Company during the Lock-Up Period. I further agree to execute and deliver such other agreements as may be reasonably requested by the Company and/or the managing underwriter which are consistent with the foregoing or which are necessary
to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to my Shares until the end of such period. I agree that the underwriters of the Company’s stock are
intended third party beneficiaries of this paragraph and shall have the right, power and authority to enforce the provisions hereof as though they were a party hereto.  

I further acknowledge that, effective upon my entering into the Stock Option Agreement with the Company pursuant to which I am
now exercising my stock option, I became a party to, and am presently and hereafter bound by, that certain Voting Agreement pursuant to which I have granted power and authority to vote all of the Shares to Harry Gruber, M.D. on all matters for which
a vote of holders of the Common Stock of the Company is required or requested as set forth in such Voting Agreement. I also agree that, upon request, I will deliver to the Company a counterpart signature page to the Voting Agreement, duly executed
by me. I agree that I have had the opportunity to review and to seek the advise of my independent legal counsel with respect to such Voting Agreement. 
  

			
	 Very truly yours,

	
	  

	 Name:
	 	  

	 Date:

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