Document:

EX-10.1

 Exhibit 10.1 

HARPOON THERAPEUTICS, INC. 

2015 EQUITY INCENTIVE PLAN 

(amended October 2, 2018 to increase share reserve) 

1. Purposes of the Plan. The purposes of this Plan are: 
  

	 	•	 	 to attract and retain the best available personnel for positions of substantial responsibility,

  

	 	•	 	 to provide additional incentive to Employees, Directors and Consultants, and 

 

	 	•	 	 to promote the success of the Company’s business. 

The Plan permits the grant of Incentive Stock Options, Nonstatutory Stock Options, Stock Appreciation Rights, Restricted Stock and Restricted
Stock Units. 
 2. Definitions. As used herein, the following definitions will apply: 

(a) “Administrator” means the Board or any of its Committees as will be administering the Plan, in accordance with
Section 4 of the Plan. 
 (b) “Applicable Laws” means the requirements relating to the administration of equity-based
awards under U.S. state corporate laws, U.S. federal and state securities laws, the Code, any stock exchange or quotation system on which the Common Stock is listed or quoted and the applicable laws of any foreign country or jurisdiction where
Awards are, or will be, granted under the Plan. 
 (c) “Award” means, individually or collectively, a grant under the Plan
of Options, Stock Appreciation Rights, Restricted Stock, or Restricted Stock Units. 
 (d) “Award Agreement” means the
written or electronic agreement setting forth the terms and provisions applicable to each Award granted under the Plan. The Award Agreement is subject to the terms and conditions of the Plan. 

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

(f) “Change in Control” means the occurrence of any of the following events: 

(i) Change in Ownership of the Company. A change in the ownership of the Company which occurs on the date that any one person, or more
than one person acting as a group (“Person”), acquires ownership of the stock of the Company that, together with the stock held by such Person, constitutes more than 50% of the total voting power of the stock of the Company, except
that any change in the ownership of the stock of the Company as a result of a private financing of the Company that is approved by the Board will not be considered a Change in Control; or 

  
 1. 

 (ii) Change in Effective Control of the Company. If the Company has a class of
securities registered pursuant to Section 12 of the Exchange Act, a change in the effective control of the Company which occurs on the date that a majority of members of the Board is replaced during any twelve (12) month period by
Directors whose appointment or election is not endorsed by a majority of the members of the Board prior to the date of the appointment or election. For purposes of this clause (ii), if any Person is considered to be in effective control of the
Company, the acquisition of additional control of the Company by the same Person will not be considered a Change in Control; or 
 (iii)
Change in Ownership of a Substantial Portion of the Company’s Assets. A change in the ownership of a substantial portion of the Company’s assets which occurs on the date that any Person acquires (or has acquired during the twelve
(12) month period ending on the date of the most recent acquisition by such person or persons) assets from the Company that have a total gross fair market value equal to or more than 50% of the total gross fair market value of all of the assets
of the Company immediately prior to such acquisition or acquisitions. For purposes of this subsection (iii), gross fair market value means the value of the assets of the Company, or the value of the assets being disposed of, determined without
regard to any liabilities associated with such assets. 
 For purposes of this Section 2(f), persons will be considered to be acting
as a group if they are owners of a corporation that enters into a merger, consolidation, purchase or acquisition of stock, or similar business transaction with the Company. 

Notwithstanding the foregoing, a transaction will not be deemed a Change in Control unless the transaction qualifies as a change in control
event within the meaning of Code Section 409A, as it has been and may be amended from time to time, and any proposed or final Treasury Regulations and Internal Revenue Service guidance that has been promulgated or may be promulgated thereunder
from time to time. 
 Further and for the avoidance of doubt, a transaction will not constitute a Change in Control if: (i) its sole
purpose is to change the jurisdiction of the Company’s incorporation, or (ii) its sole purpose is to create a holding company that will be owned in substantially the same proportions by the persons who held the Company’s securities
immediately before such transaction. 
 (g) “Code” means the Internal Revenue Code of 1986, as amended. Any reference to a
section of the Code herein will be a reference to any successor or amended section of the Code. 
 (h) “Committee” means a
committee of Directors or of other individuals satisfying Applicable Laws appointed by the Board, or by the compensation committee of the Board, in accordance with Section 4 hereof. 

(i) “Common Stock” means the common stock of the Company. 

  
 2. 

 (j) “Company” means Harpoon Therapeutics, Inc., Inc., a Delaware
corporation, or any successor thereto. 
 (k) “Consultant” means any person, including an advisor, engaged by the Company or
a Parent or Subsidiary to render services to such entity. 
 (l) “Director” means a member of the Board. 

(m) “Disability” means total and permanent disability as defined in Code Section 22(e)(3), provided that in the case of
Awards other than Incentive Stock Options, the Administrator in its discretion may determine whether a permanent and total disability exists in accordance with uniform and non-discriminatory standards adopted
by the Administrator from time to time. 
 (n) “Employee” means any person, including officers and Directors, employed by
the Company or any Parent or Subsidiary of the Company. Neither service as a Director nor payment of a director’s fee by the Company will be sufficient to constitute “employment” by the Company. 

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

(p) “Exchange Program” means a program under which (i) outstanding Awards are surrendered or cancelled in exchange for
Awards of the same type (which may have higher or lower exercise prices and different terms), Awards of a different type, and/or cash, (ii) Participants would have the opportunity to transfer any outstanding Awards to a financial institution or
other person or entity selected by the Administrator, and/or (iii) the exercise price of an outstanding Award is reduced or increased. The Administrator will determine the terms and conditions of any Exchange Program in its sole discretion.

 (q) “Fair Market Value” means, as of any date, the value of Common Stock determined as follows: 

(i) If the Common Stock is listed on any established stock exchange or a national market system, including without limitation the Nasdaq
Global Select Market, the Nasdaq Global Market or the Nasdaq Capital Market of The Nasdaq Stock Market, its Fair Market Value will be the closing sales price for such stock (or the closing bid, if no sales were reported) as quoted on such exchange
or system on the day of determination, as reported in The Wall Street Journal or such other source as the Administrator deems reliable; 

(ii) If the Common Stock is regularly quoted by a recognized securities dealer but selling prices are not reported, the Fair Market Value of a
Share will be the mean between the high bid and low asked prices for the Common Stock on the day of determination (or, if no bids and asks were reported on that date, as applicable, on the last trading date such bids and asks were reported), as
reported in The Wall Street Journal or such other source as the Administrator deems reliable; or 
 (iii) In the absence of an
established market for the Common Stock, the Fair Market Value will be determined in good faith by the Administrator. 

  
 3. 

 (r) “Incentive Stock Option” means an Option that by its terms qualifies
and is otherwise intended to qualify as an incentive stock option within the meaning of Code Section 422 and the regulations promulgated thereunder. 

(s) “Nonstatutory Stock Option” means an Option that by its terms does not qualify or is not intended to qualify as an
Incentive Stock Option. 
 (t) “Option” means a stock option granted pursuant to the Plan. 

(u) “Parent” means a “parent corporation,” whether now or hereafter existing, as defined in Code
Section 424(e). 
 (v) “Participant” means the holder of an outstanding Award. 

(w) “Period of Restriction” means the period during which the transfer of Shares of Restricted Stock are subject to
restrictions and therefore, the Shares are subject to a substantial risk of forfeiture. Such restrictions may be based on the passage of time, the achievement of target levels of performance, or the occurrence of other events as determined by the
Administrator. 
 (x) “Plan” means this 2015 Equity Incentive Plan. 

(y) “Restricted Stock” means Shares issued pursuant to an Award of Restricted Stock under Section 8 of the Plan, or
issued pursuant to the early exercise of an Option. 
 (z) “Restricted Stock Unit” means a bookkeeping entry representing an
amount equal to the Fair Market Value of one Share, granted pursuant to Section 9. Each Restricted Stock Unit represents an unfunded and unsecured obligation of the Company. 

(aa) “Service Provider” means an Employee, Director or Consultant. 

(bb) “Share” means a share of the Common Stock, as adjusted in accordance with Section 13 of the Plan. 

(cc) “Stock Appreciation Right” means an Award, granted alone or in connection with an Option, that pursuant to Section 7
is designated as a Stock Appreciation Right. 
 (dd) “Subsidiary” means a “subsidiary corporation,” whether now or
hereafter existing, as defined in Code Section 424(f). 
 3. Stock Subject to the Plan. 

(a) Stock Subject to the Plan. Subject to the provisions of Section 13 of the Plan, the maximum aggregate number of Shares that may
be subject to Awards and sold under the Plan is 15,188,950 Shares. The Shares may be authorized but unissued, or reacquired Common Stock. 

  
 4. 

 (b) Lapsed Awards. If an Award expires or becomes unexercisable without having been
exercised in full, is surrendered pursuant to an Exchange Program, or, with respect to Restricted Stock or Restricted Stock Units, is forfeited to or repurchased by the Company due to the failure to vest, the unpurchased Shares (or for Awards other
than Options or Stock Appreciation Rights the forfeited or repurchased Shares) which were subject thereto will become available for future grant or sale under the Plan (unless the Plan has terminated). With respect to Stock Appreciation Rights, only
Shares actually issued pursuant to a Stock Appreciation Right will cease to be available under the Plan; all remaining Shares under Stock Appreciation Rights will remain available for future grant or sale under the Plan (unless the Plan has
terminated). Shares that have actually been issued under the Plan under any Award will not be returned to the Plan and will not become available for future distribution under the Plan; provided, however, that if Shares issued pursuant to Awards of
Restricted Stock or Restricted Stock Units are repurchased by the Company or are forfeited to the Company due to the failure to vest, such Shares will become available for future grant under the Plan. Shares used to pay the exercise price of an
Award or to satisfy the tax withholding obligations related to an Award will become available for future grant or sale under the Plan. To the extent an Award under the Plan is paid out in cash rather than Shares, such cash payment will not result in
reducing the number of Shares available for issuance under the Plan. Notwithstanding the foregoing and, subject to adjustment as provided in Section 13, the maximum number of Shares that may be issued upon the exercise of Incentive Stock
Options will equal the aggregate Share number stated in Section 3(a), plus, to the extent allowable under Code Section 422 and the Treasury Regulations promulgated thereunder, any Shares that become available for issuance under the Plan
pursuant to Section 3(b). 
 (c) Share Reserve. The Company, during the term of this Plan, will at all times reserve and keep
available such number of Shares as will be sufficient to satisfy the requirements of the Plan. 
 4. Administration of the Plan. 

(a) Procedure. 
 (i)
Multiple Administrative Bodies. Different Committees with respect to different groups of Service Providers may administer the Plan. 

(ii) Other Administration. Other than as provided above, the Plan will be administered by (A) the Board or (B) a Committee,
which Committee will be constituted to satisfy Applicable Laws. 
 (b) Powers of the Administrator. Subject to the provisions of the
Plan, and in the case of a Committee, subject to the specific duties delegated by the Board to such Committee, the Administrator will have the authority, in its discretion: 

(i) to determine the Fair Market Value; 

(ii) to select the Service Providers to whom Awards may be granted hereunder; 

(iii) to determine the number of Shares to be covered by each Award granted hereunder; 

  
 5. 

 (iv) to approve forms of Award Agreements for use under the Plan; 

(v) to determine the terms and conditions, not inconsistent with the terms of the Plan, of any Award granted hereunder. Such terms and
conditions include, but are not limited to, the exercise price, the time or times when Awards may be exercised (which may be based on performance criteria), any vesting acceleration or waiver of forfeiture restrictions, and any restriction or
limitation regarding any Award or the Shares relating thereto, based in each case on such factors as the Administrator will determine; 

(vi) to institute and determine the terms and conditions of an Exchange Program; 

(vii) to construe and interpret the terms of the Plan and Awards granted pursuant to the Plan; 

(viii) to prescribe, amend and rescind rules and regulations relating to the Plan, including rules and regulations relating to sub-plans established for the purpose of satisfying applicable foreign laws or for qualifying for favorable tax treatment under applicable foreign laws; 

(ix) to modify or amend each Award (subject to Section 18(c) of the Plan), including but not limited to the discretionary authority to
extend the post-termination exercisability period of Awards and to extend the maximum term of an Option (subject to Section 6(d)); 

(x) to allow Participants to satisfy withholding tax obligations in a manner prescribed in Section 14; 

(xi) to authorize any person to execute on behalf of the Company any instrument required to effect the grant of an Award previously granted by
the Administrator; 
 (xii) to allow a Participant to defer the receipt of the payment of cash or the delivery of Shares that otherwise
would be due to such Participant under an Award; and 
 (xiii) to make all other determinations deemed necessary or advisable for
administering the Plan. 
 (c) Effect of Administrator’s Decision. The Administrator’s decisions, determinations and
interpretations will be final and binding on all Participants and any other holders of Awards. 
 5. Eligibility. Nonstatutory Stock
Options, Stock Appreciation Rights, Restricted Stock, and Restricted Stock Units may be granted to Service Providers. Incentive Stock Options may be granted only to Employees. 

  
 6. 

 6. Stock Options. 

(a) Grant of Options. Subject to the terms and provisions of the Plan, the Administrator, at any time and from time to time, may grant
Options in such amounts as the Administrator, in its sole discretion, will determine. 
 (b) Option Agreement. Each Award of an Option
will be evidenced by an Award Agreement that will specify the exercise price, the term of the Option, the number of Shares subject to the Option, the exercise restrictions, if any, applicable to the Option, and such other terms and conditions as the
Administrator, in its sole discretion, will determine. 
 (c) Limitations. Each Option will be designated in the Award Agreement as
either an Incentive Stock Option or a Nonstatutory Stock Option. Notwithstanding such designation, however, to the extent that the aggregate Fair Market Value of the Shares with respect to which Incentive Stock Options are exercisable for the first
time by the Participant during any calendar year (under all plans of the Company and any Parent or Subsidiary) exceeds one hundred thousand dollars ($100,000), such Options will be treated as Nonstatutory Stock Options. For purposes of this
Section 6(c), Incentive Stock Options will be taken into account in the order in which they were granted, the Fair Market Value of the Shares will be determined as of the time the Option with respect to such Shares is granted, and calculation
will be performed in accordance with Code Section 422 and Treasury Regulations promulgated thereunder. 
 (d) Term of Option. The
term of each Option will be stated in the Award Agreement; provided, however, that the term will be no more than ten (10) years from the date of grant thereof. In the case of an Incentive Stock Option granted to a Participant who, at the time
the Incentive Stock Option is granted, owns stock representing more than ten percent (10%) of the total combined voting power of all classes of stock of the Company or any Parent or Subsidiary, the term of the Incentive Stock Option will be five
(5) years from the date of grant or such shorter term as may be provided in the Award Agreement. 
 (e) Option Exercise Price and
Consideration. 
 (i) Exercise Price. The per Share exercise price for the Shares to be issued pursuant to the exercise of an
Option will be determined by the Administrator, but will be no less than one hundred percent (100%) of the Fair Market Value per Share on the date of grant. In addition, in the case of an Incentive Stock Option granted to an Employee who owns stock
representing more than ten percent (10%) of the voting power of all classes of stock of the Company or any Parent or Subsidiary, the per Share exercise price will be no less than one hundred ten percent (110%) of the Fair Market Value per Share on
the date of grant. Notwithstanding the foregoing provisions of this Section 6(e)(i), Options may be granted with a per Share exercise price of less than one hundred percent (100%) of the Fair Market Value per Share on the date of grant pursuant
to a transaction described in, and in a manner consistent with, Code Section 424(a). 
 (ii) Waiting Period and Exercise Dates.
At the time an Option is granted, the Administrator will fix the period within which the Option may be exercised and will determine any conditions that must be satisfied before the Option may be exercised. 

  
 7. 

 (iii) Form of Consideration. The Administrator will determine the acceptable form of
consideration for exercising an Option, including the method of payment. In the case of an Incentive Stock Option, the Administrator will determine the acceptable form of consideration at the time of grant. Such consideration may consist entirely
of: (1) cash; (2) check; (3) promissory note, to the extent permitted by Applicable Laws, (4) other Shares, provided that such Shares have a Fair Market Value on the date of surrender equal to the aggregate exercise price of the
Shares as to which such Option will be exercised and provided further that accepting such Shares will not result in any adverse accounting consequences to the Company, as the Administrator determines in its sole discretion; (5) consideration
received by the Company under cashless exercise program (whether through a broker or otherwise) implemented by the Company in connection with the Plan; (6) by net exercise, (7) such other consideration and method of payment for the
issuance of Shares to the extent permitted by Applicable Laws, or (8) any combination of the foregoing methods of payment. In making its determination as to the type of consideration to accept, the Administrator will consider if acceptance of
such consideration may be reasonably expected to benefit the Company. 
 (f) Exercise of Option. 

(i) Procedure for Exercise; Rights as a Stockholder. Any Option granted hereunder will be exercisable according to the terms of the
Plan and at such times and under such conditions as determined by the Administrator and set forth in the Award Agreement. An Option may not be exercised for a fraction of a Share. 

An Option will be deemed exercised when the Company receives: (i) notice of exercise (in such form as the Administrator may specify from
time to time) from the person entitled to exercise the Option, and (ii) full payment for the Shares with respect to which the Option is exercised (together with applicable tax withholding). Full payment may consist of any consideration and
method of payment authorized by the Administrator and permitted by the Award Agreement and the Plan. Shares issued upon exercise of an Option will be issued in the name of the Participant or, if requested by the Participant, in the name of the
Participant and his or her spouse. Until the Shares are issued (as evidenced by the appropriate entry on the books of the Company or of a duly authorized transfer agent of the Company), no right to vote or receive dividends or any other rights as a
stockholder will exist with respect to the Shares subject to an Option, notwithstanding the exercise of the Option. The Company will issue (or cause to be issued) such Shares promptly after the Option is exercised. No adjustment will be made for a
dividend or other right for which the record date is prior to the date the Shares are issued, except as provided in Section 13 of the Plan. 

Exercising an Option in any manner will decrease the number of Shares thereafter available, both for purposes of the Plan and for sale under
the Option, by the number of Shares as to which the Option is exercised. 
 (ii) Termination of Relationship as a Service Provider.
If a Participant ceases to be a Service Provider, other than upon the Participant’s termination as the result of the Participant’s death or Disability, the Participant may exercise his or her Option within thirty (30) days of
termination, or such longer period of time as is specified in the Award Agreement (but in no event later than the expiration of the term of such Option as set forth in the Award Agreement) 

  
 8. 

 
to the extent that the Option is vested on the date of termination. Unless otherwise provided by the Administrator, if on the date of termination the Participant is not vested as to his or her
entire Option, the Shares covered by the unvested portion of the Option will revert to the Plan. If after termination the Participant does not exercise his or her Option within the time specified by the Administrator, the Option will terminate, and
the Shares covered by such Option will revert to the Plan. 
 (iii) Disability of Participant. If a Participant ceases to be a
Service Provider as a result of the Participant’s Disability, the Participant may exercise his or her Option within six (6) months of termination, or such longer period of time as is specified in the Award Agreement (but in no event later
than the expiration of the term of such Option as set forth in the Award Agreement) to the extent the Option is vested on the date of termination. Unless otherwise provided by the Administrator, if on the date of termination the Participant is not
vested as to his or her entire Option, the Shares covered by the unvested portion of the Option will revert to the Plan. If after termination the Participant does not exercise his or her Option within the time specified herein, the Option will
terminate, and the Shares covered by such Option will revert to the Plan. 
 (iv) Death of Participant. If a Participant dies while a
Service Provider, the Option may be exercised within six (6) months following the Participant’s death, or within such longer period of time as is specified in the Award Agreement (but in no event later than the expiration of the term of
such Option as set forth in the Award Agreement) to the extent that the Option is vested on the date of death, by the Participant’s designated beneficiary, provided such beneficiary has been designated prior to the Participant’s death in a
form acceptable to the Administrator. If no such beneficiary has been designated by the Participant, then such Option may be exercised by the personal representative of the Participant’s estate or by the person(s) to whom the Option is
transferred pursuant to the Participant’s will or in accordance with the laws of descent and distribution. Unless otherwise provided by the Administrator, if at the time of death Participant is not vested as to his or her entire Option, the
Shares covered by the unvested portion of the Option will immediately revert to the Plan. If the Option is not so exercised within the time specified herein, the Option will terminate, and the Shares covered by such Option will revert to the Plan.

 7. Stock Appreciation Rights. 

(a) Grant of Stock Appreciation Rights. Subject to the terms and conditions of the Plan, a Stock Appreciation Right may be granted to
Service Providers at any time and from time to time as will be determined by the Administrator, in its sole discretion. 
 (b) Number of
Shares. The Administrator will have complete discretion to determine the number of Shares subject to any Award of Stock Appreciation Rights. 

(c) Exercise Price and Other Terms. The per Share exercise price for the Shares that will determine the amount of the payment to be
received upon exercise of a Stock Appreciation Right as set forth in Section 7(f) will be determined by the Administrator and will be no less than one hundred percent (100%) of the Fair Market Value per Share on the date of grant. Otherwise,
the Administrator, subject to the provisions of the Plan, will have complete discretion to determine the terms and conditions of Stock Appreciation Rights granted under the Plan. 

  
 9. 

 (d) Stock Appreciation Right Agreement. Each Stock Appreciation Right grant will be
evidenced by an Award Agreement that will specify the exercise price, the term of the Stock Appreciation Right, the conditions of exercise, and such other terms and conditions as the Administrator, in its sole discretion, will determine. 

(e) Expiration of Stock Appreciation Rights. A Stock Appreciation Right granted under the Plan will expire upon the date determined by
the Administrator, in its sole discretion, and set forth in the Award Agreement. Notwithstanding the foregoing, the rules of Section 6(d) relating to the maximum term and Section 6(f) relating to exercise also will apply to Stock
Appreciation Rights. 
 (f) Payment of Stock Appreciation Right Amount. Upon exercise of a Stock Appreciation Right, a Participant
will be entitled to receive payment from the Company in an amount determined by multiplying: 
 (i) The difference between the Fair Market
Value of a Share on the date of exercise over the exercise price; times 
 (ii) The number of Shares with respect to which the Stock
Appreciation Right is exercised. 
 At the discretion of the Administrator, the payment upon Stock Appreciation Right exercise may be in
cash, in Shares of equivalent value, or in some combination thereof. 
 8. Restricted Stock. 

(a) Grant of Restricted Stock. Subject to the terms and provisions of the Plan, the Administrator, at any time and from time to time,
may grant Shares of Restricted Stock to Service Providers in such amounts as the Administrator, in its sole discretion, will determine. 

(b) Restricted Stock Agreement. Each Award of Restricted Stock will be evidenced by an Award Agreement that will specify the Period of
Restriction, the number of Shares granted, and such other terms and conditions as the Administrator, in its sole discretion, will determine. Unless the Administrator determines otherwise, the Company as escrow agent will hold Shares of Restricted
Stock until the restrictions on such Shares have lapsed. 
 (c) Transferability. Except as provided in this Section 8 or as the
Administrator determines, Shares of Restricted Stock may not be sold, transferred, pledged, assigned, or otherwise alienated or hypothecated until the end of the applicable Period of Restriction. 

(d) Other Restrictions. The Administrator, in its sole discretion, may impose such other restrictions on Shares of Restricted Stock as
it may deem advisable or appropriate. 

  
 10. 

 (e) Removal of Restrictions. Except as otherwise provided in this Section 8,
Shares of Restricted Stock covered by each Restricted Stock grant made under the Plan will be released from escrow as soon as practicable after the last day of the Period of Restriction or at such other time as the Administrator may determine. The
Administrator, in its discretion, may accelerate the time at which any restrictions will lapse or be removed. 
 (f) Voting Rights.
During the Period of Restriction, Service Providers holding Shares of Restricted Stock granted hereunder may exercise full voting rights with respect to those Shares, unless the Administrator determines otherwise. 

(g) Dividends and Other Distributions. During the Period of Restriction, Service Providers holding Shares of Restricted Stock will be
entitled to receive all dividends and other distributions paid with respect to such Shares, unless the Administrator provides otherwise. If any such dividends or distributions are paid in Shares, the Shares will be subject to the same restrictions
on transferability and forfeitability as the Shares of Restricted Stock with respect to which they were paid. 
 (h) Return of Restricted
Stock to Company. On the date set forth in the Award Agreement, the Restricted Stock for which restrictions have not lapsed will revert to the Company and again will become available for grant under the Plan. 

9. Restricted Stock Units. 

(a) Grant. Restricted Stock Units may be granted at any time and from time to time as determined by the Administrator. After the
Administrator determines that it will grant Restricted Stock Units, it will advise the Participant in an Award Agreement of the terms, conditions, and restrictions related to the grant, including the number of Restricted Stock Units. 

(b) Vesting Criteria and Other Terms. The Administrator will set vesting criteria in its discretion, which, depending on the extent to
which the criteria are met, will determine the number of Restricted Stock Units that will be paid out to the Participant. The Administrator may set vesting criteria based upon the achievement of Company-wide, business unit, or individual goals
(including, but not limited to, continued employment or service), or any other basis determined by the Administrator in its discretion. 

(c) Earning Restricted Stock Units. Upon meeting the applicable vesting criteria, the Participant will be entitled to receive a payout
as determined by the Administrator. Notwithstanding the foregoing, at any time after the grant of Restricted Stock Units, the Administrator, in its sole discretion, may reduce or waive any vesting criteria that must be met to receive a payout. 

(d) Form and Timing of Payment. Payment of earned Restricted Stock Units will be made as soon as practicable after the date(s)
determined by the Administrator and set forth in the Award Agreement. The Administrator, in its sole discretion, may settle earned Restricted Stock Units in cash, Shares, or a combination of both. 

(e) Cancellation. On the date set forth in the Award Agreement, all unearned Restricted Stock Units will be forfeited to the Company.

  
 11. 

 10. Compliance With Code Section 409A. Awards will be designed and
operated in such a manner that they are either exempt from the application of, or comply with, the requirements of Code Section 409A, except as otherwise determined in the sole discretion of the Administrator. The Plan and each Award Agreement
under the Plan is intended to meet the requirements of Code Section 409A and will be construed and interpreted in accordance with such intent, except as otherwise determined in the sole discretion of the Administrator. To the extent that an
Award or payment, or the settlement or deferral thereof, is subject to Code Section 409A the Award will be granted, paid, settled or deferred in a manner that will meet the requirements of Code Section 409A, such that the grant, payment,
settlement or deferral will not be subject to the additional tax or interest applicable under Code Section 409A. 
 11. Leaves of
Absence/Transfer Between Locations. Unless the Administrator provides otherwise, vesting of Awards granted hereunder will be suspended during any unpaid leave of absence. A Participant will not cease to be an Employee in the case of (i) any
leave of absence approved by the Company or (ii) transfers between locations of the Company or between the Company, its Parent, or any Subsidiary. For purposes of Incentive Stock Options, no such leave may exceed three (3) months, unless
reemployment upon expiration of such leave is guaranteed by statute or contract. If reemployment upon expiration of a leave of absence approved by the Company is not so guaranteed, then six (6) months following the first (1st) day of such leave, any Incentive Stock Option held by the Participant will cease to be treated as an Incentive Stock Option and will be treated for tax purposes as a Nonstatutory Stock Option. 

12. Limited Transferability of Awards. 

(a) Unless determined otherwise by the Administrator, Awards may not be sold, pledged, assigned, hypothecated, or otherwise transferred in any
manner other than by will or by the laws of descent and distribution, and may be exercised, during the lifetime of the Participant, only by the Participant. If the Administrator makes an Award transferable, such Award may only be transferred
(i) by will, (ii) by the laws of descent and distribution, or (iii) as permitted by Rule 701 of the Securities Act of 1933, as amended (the “Securities Act”). 

(b) Further, until the Company becomes subject to the reporting requirements of Section 13 or 15(d) of the Exchange Act, or after the
Administrator determines that it is, will, or may no longer be relying upon the exemption from registration under the Exchange Act as set forth in Rule 12h-1(f) promulgated under the Exchange Act, an Option,
or prior to exercise, the Shares subject to the Option, may not be pledged, hypothecated or otherwise transferred or disposed of, in any manner, including by entering into any short position, any “put equivalent position” or any “call
equivalent position” (as defined in Rule 16a-1(h) and Rule 16a-1(b) of the Exchange Act, respectively), other than to (i) persons who are “family
members” (as defined in Rule 701(c)(3) of the Securities Act) through gifts or domestic relations orders, or (ii) to an executor or guardian of the Participant upon the death or disability of the Participant. Notwithstanding the foregoing
sentence, the Administrator, in its sole discretion, may determine to permit transfers to the Company or in connection with a Change in Control or other acquisition transactions involving the Company to the extent permitted by Rule 12h-1(f). 

  
 12. 

 13. Adjustments; Dissolution or Liquidation; Merger or Change in Control. 

(a) Adjustments. In the event that any dividend or other distribution (whether in the form of cash, Shares, other securities, or other
property), recapitalization, stock split, reverse stock split, reorganization, merger, consolidation, split-up, spin-off, combination, repurchase, or exchange of Shares
or other securities of the Company, or other change in the corporate structure of the Company affecting the Shares occurs, the Administrator, in order to prevent diminution or enlargement of the benefits or potential benefits intended to be made
available under the Plan, will adjust the number and class of shares of stock that may be delivered under the Plan and/or the number, class, and price of shares of stock covered by each outstanding Award; provided, however, that the Administrator
will make such adjustments to an Award required by Section 25102(o) of the California Corporations Code to the extent the Company is relying upon the exemption afforded thereby with respect to the Award. 

(b) Dissolution or Liquidation. In the event of the proposed dissolution or liquidation of the Company, the Administrator will notify
each Participant as soon as practicable prior to the effective date of such proposed transaction. To the extent it has not been previously exercised, an Award will terminate immediately prior to the consummation of such proposed action. 

(c) Merger or Change in Control. In the event of a merger of the Company with or into another corporation or other entity or a Change in
Control, each outstanding Award will be treated as the Administrator determines (subject to the provisions of the following paragraph) without a Participant’s consent, including, without limitation, that (i) Awards will be assumed, or
substantially equivalent Awards will be substituted, by the acquiring or succeeding corporation (or an affiliate thereof) with appropriate adjustments as to the number and kind of shares and prices; (ii) upon written notice to a Participant,
that the Participant’s Awards will terminate upon or immediately prior to the consummation of such merger or Change in Control; (iii) outstanding Awards will vest and become exercisable, realizable, or payable, or restrictions applicable
to an Award will lapse, in whole or in part prior to or upon consummation of such merger or Change in Control, and, to the extent the Administrator determines, terminate upon or immediately prior to the effectiveness of such merger or Change in
Control; (iv) (A) the termination of an Award in exchange for an amount of cash and/or property, if any, equal to the amount that would have been attained upon the exercise of such Award or realization of the Participant’s rights as of the
date of the occurrence of the transaction (and, for the avoidance of doubt, if as of the date of the occurrence of the transaction the Administrator determines in good faith that no amount would have been attained upon the exercise of such Award or
realization of the Participant’s rights, then such Award may be terminated by the Company without payment), or (B) the replacement of such Award with other rights or property selected by the Administrator in its sole discretion; or
(v) any combination of the foregoing. In taking any of the actions permitted under this subsection 13(c), the Administrator will not be obligated to treat all Awards, all Awards held by a Participant, or all Awards of the same type, similarly.

 In the event that the successor corporation does not assume or substitute for the Award (or portion thereof), the Participant will fully
vest in and have the right to exercise all of his or her outstanding Options and Stock Appreciation Rights, including Shares as to which such Awards would not otherwise be vested or exercisable, all restrictions on Restricted Stock and

  
 13. 

 
Restricted Stock Units will lapse, and, with respect to Awards with performance-based vesting, all performance goals or other vesting criteria will be deemed achieved at one hundred percent
(100%) of target levels and all other terms and conditions met. In addition, if an Option or Stock Appreciation Right is not assumed or substituted in the event of a merger or Change in Control, the Administrator will notify the Participant in
writing or electronically that the Option or Stock Appreciation Right will be exercisable for a period of time determined by the Administrator in its sole discretion, and the Option or Stock Appreciation Right will terminate upon the expiration of
such period. 
 For the purposes of this subsection 13(c), an Award will be considered assumed if, following the merger or Change in
Control, the Award confers the right to purchase or receive, for each Share subject to the Award immediately prior to the merger or Change in Control, the consideration (whether stock, cash, or other securities or property) received in the merger or
Change in Control by holders of Common Stock for each Share held on the effective date of the transaction (and if holders were offered a choice of consideration, the type of consideration chosen by the holders of a majority of the outstanding
Shares); provided, however, that if such consideration received in the merger or Change in Control is not solely common stock of the successor corporation or its Parent, the Administrator may, with the consent of the successor corporation, provide
for the consideration to be received upon the exercise of an Option or Stock Appreciation Right or upon the payout of a Restricted Stock Unit, for each Share subject to such Award, to be solely common stock of the successor corporation or its Parent
equal in fair market value to the per share consideration received by holders of Common Stock in the merger or Change in Control. 

Notwithstanding anything in this Section 13(c) to the contrary, an Award that vests, is earned or
paid-out upon the satisfaction of one or more performance goals will not be considered assumed if the Company or its successor modifies any of such performance goals without the Participant’s consent;
provided, however, a modification to such performance goals only to reflect the successor corporation’s post-Change in Control corporate structure will not be deemed to invalidate an otherwise valid Award assumption. 

Notwithstanding anything in this Section 13(c) to the contrary, if a payment under an Award Agreement is subject to Code
Section 409A and if the change in control definition contained in the Award Agreement does not comply with the definition of “change of control” for purposes of a distribution under Code Section 409A, then any payment of an
amount that is otherwise accelerated under this Section will be delayed until the earliest time that such payment would be permissible under Code Section 409A without triggering any penalties applicable under Code Section 409A. 

14. Tax Withholding. 
 (a)
Withholding Requirements. Prior to the delivery of any Shares or cash pursuant to an Award (or exercise thereof), the Company will have the power and the right to deduct or withhold, or require a Participant to remit to the Company, an amount
sufficient to satisfy federal, state, local, foreign or other taxes (including the Participant’s FICA obligation) required to be withheld with respect to such Award (or exercise thereof). 

  
 14. 

 (b) Withholding Arrangements. The Administrator, in its sole discretion and pursuant
to such procedures as it may specify from time to time, may permit a Participant to satisfy such tax withholding obligation, in whole or in part by (without limitation) (i) paying cash, (ii) electing to have the Company withhold otherwise
deliverable Shares having a Fair Market Value equal to the minimum statutory amount required to be withheld, (iii) delivering to the Company already-owned Shares having a Fair Market Value equal to the statutory amount required to be withheld,
provided the delivery of such Shares will not result in any adverse accounting consequences, as the Administrator determines in its sole discretion, or (iv) selling a sufficient number of Shares otherwise deliverable to the Participant through
such means as the Administrator may determine in its sole discretion (whether through a broker or otherwise) equal to the amount required to be withheld. The amount of the withholding requirement will be deemed to include any amount which the
Administrator agrees may be withheld at the time the election is made, not to exceed the amount determined by using the maximum federal, state or local marginal income tax rates applicable to the Participant with respect to the Award on the date
that the amount of tax to be withheld is to be determined. The Fair Market Value of the Shares to be withheld or delivered will be determined as of the date that the taxes are required to be withheld. 

15. No Effect on Employment or Service. Neither the Plan nor any Award will confer upon a Participant any right with respect to
continuing the Participant’s relationship as a Service Provider with the Company, nor will they interfere in any way with the Participant’s right or the Company’s right to terminate such relationship at any time, with or without
cause, to the extent permitted by Applicable Laws. 
 16. Date of Grant. The date of grant of an Award will be, for all purposes, the
date on which the Administrator makes the determination granting such Award, or such other later date as is determined by the Administrator. Notice of the determination will be provided to each Participant within a reasonable time after the date of
such grant. 
 17. Term of Plan. Subject to Section 21 of the Plan, the Plan will become effective upon its adoption by the
Board. Unless sooner terminated under Section 18, it will continue in effect for a term of ten (10) years from the later of (a) the effective date of the Plan, or (b) the earlier of the most recent Board or stockholder approval
of an increase in the number of Shares reserved for issuance under the Plan. 
 18. Amendment and Termination of the Plan. 

(a) Amendment and Termination. The Board may at any time amend, alter, suspend or terminate the Plan. 

(b) Stockholder Approval. The Company will obtain stockholder approval of any Plan amendment to the extent necessary and desirable to
comply with Applicable Laws. 
 (c) Effect of Amendment or Termination. No amendment, alteration, suspension or termination of the
Plan will impair the rights of any Participant, unless mutually agreed otherwise between the Participant and the Administrator, which agreement must be in writing and signed by the Participant and the Company. Termination of the Plan will not affect
the Administrator’s ability to exercise the powers granted to it hereunder with respect to Awards granted under the Plan prior to the date of such termination. 

  
 15. 

 19. Conditions Upon Issuance of Shares. 

(a) Legal Compliance. Shares will not be issued pursuant to the exercise of an Award unless the exercise of such Award and the issuance
and delivery of such Shares will comply with Applicable Laws and will be further subject to the approval of counsel for the Company with respect to such compliance. 

(b) Investment Representations. As a condition to the exercise of an Award, the Company may require the person exercising such Award to
represent and warrant at the time of any such exercise that the Shares are being purchased only for investment and without any present intention to sell or distribute such Shares if, in the opinion of counsel for the Company, such a representation
is required. 
 20. Inability to Obtain Authority. The inability of the Company to obtain authority from any regulatory body having
jurisdiction, which authority is deemed by the Company’s counsel to be necessary to the lawful issuance and sale of any Shares hereunder, will relieve the Company of any liability in respect of the failure to issue or sell such Shares as to
which such requisite authority will not have been obtained. 
 21. Stockholder Approval. The Plan will be subject to approval by the
stockholders of the Company within twelve (12) months after the date the Plan is adopted by the Board. Such stockholder approval will be obtained in the manner and to the degree required under Applicable Laws. 

22. Information to Participants. Beginning on the earlier of (a) the date that the aggregate number of Participants under this Plan
is two thousand (2,000) or more or the aggregate number of Participants under this Plan who are not accredited investors (as defined in Rule 501(a) of Regulation D promulgate by the Securities and Exchange Committee under the Securities Act) is five
hundred (500) or more and (b) the date that the Company is required to deliver information to Participants pursuant to Rule 701 under the Securities Act, and until such time as the Company becomes subject to the reporting requirements of
Section 13 or 15(d) of the Exchange Act, is no longer relying on the exemption provided by Rule 12h-1(f)(1) under the Exchange Act or is no longer required to deliver information to Participants pursuant
to Rule 701 under the Securities Act, the Company shall provide to each Participant the information described in paragraphs (e)(3), (4), and (5) of Rule 701 under the Securities Act not less frequently than every six (6) months with the
financial statements being not more than 180 days old and with such information provided either by physical or electronic delivery to the Participants or by written notice to the Participants of the availability of the information on an Internet
site that may be password-protected and of any password needed to access the information. The Company may request that Participants agree to keep the information to be provided pursuant to this section confidential. If a Participant does not agree
to keep the information to be provided pursuant to this section confidential, then the Company will not be required to provide the information unless otherwise required pursuant to Rule 12h¬1 (f)(1) under the Exchange Act or Rule 701 of the
Securities Act. 

  
 16. 

 HARPOON THERAPEUTICS, INC. 

2015 EQUITY INCENTIVE PLAN 

STOCK OPTION AGREEMENT — EARLY EXERCISE 

Unless otherwise defined herein, the terms defined in the 2015 Equity Incentive Plan (the “Plan”) shall have the same defined
meanings in this Stock Option Agreement – Early Exercise (the “Option Agreement”). 
  

	I.	 NOTICE OF STOCK OPTION GRANT 

 

							
		 	Name:	  	  
	  	
				
		 	Address:	  	  
	  	

 The undersigned Participant has been granted an Option to purchase Common Stock of the Company, subject to the
terms and conditions of the Plan and this Option Agreement, as follows: 
 Date of Grant:     

Vesting Commencement Date: 

Exercise Price per Share:     

Total Number of Shares Granted:     

Total Exercise Price:      
  

							
		 	Type of Option:	 	            	  	Incentive Stock Option
				
		 		 	            	  	Nonstatutory Stock Option

 Term/Expiration Date:     

Vesting Schedule: 
 This
Option shall be exercisable, in whole or in part, according to the following vesting schedule: 
 One forty-eighth (1/48th) of the Shares subject to the Option shall vest each month thereafter on the same day of the month as the Vesting Commencement Date (and if there is no corresponding day, on the last day of the
month), subject to Participant continuing to be a Service Provider through each such date. 

 Termination Period: 

This Option shall be exercisable for three (3) months after Participant ceases to be a Service Provider, unless such termination is due to
Participant’s death or Disability, in which case this Option shall be exercisable for twelve (12) months after Participant ceases to be a Service Provider. Notwithstanding the foregoing sentence, in no event may this Option be exercised
after the Term/Expiration Date as provided above and this Option may be subject to earlier termination as provided in Section 13 of the Plan. 
  

	II.	 AGREEMENT 

1. Grant of Option. The Administrator of the Company hereby grants to the Participant named in the Notice of Stock Option Grant in Part
I of this Agreement (“Participant”), an option (the “Option”) to purchase the number of Shares set forth in the Notice of Stock Option Grant, at the exercise price per Share set forth in the Notice of Stock Option Grant (the
“Exercise Price”), and subject to the terms and conditions of the Plan, which is incorporated herein by reference. Subject to Section 18 of the Plan, in the event of a conflict between the terms and conditions of the Plan and this
Option Agreement, the terms and conditions of the Plan shall prevail. 
 If designated in the Notice of Stock Option Grant as an Incentive
Stock Option (“ISO”), this Option is intended to qualify as an Incentive Stock Option as defined in Section 422 of the Code. Nevertheless, to the extent that it exceeds the $100,000 rule of Code Section 422(d), this Option shall
be treated as a Nonstatutory Stock Option (“NSO”). Further, if for any reason this Option (or portion thereof) shall not qualify as an ISO, then, to the extent of such nonqualification, such Option (or portion thereof) shall be regarded as
a NSO granted under the Plan. In no event shall the Administrator, the Company or any Parent or Subsidiary or any of their respective employees or directors have any liability to Participant (or any other person) due to the failure of the Option to
qualify for any reason as an ISO. 
 2. Exercise of Option. This Option shall be exercisable during its term in accordance with the
applicable provisions of the Plan as follows: 
 (a) Right to Exercise. 

(i) Subject to subsections 2(a)(ii) and 2(a)(iii) below, this Option shall be exercisable cumulatively according to the vesting schedule
set forth in the Notice of Stock Option Grant. Alternatively, at the election of Participant, this Option may be exercised in whole or in part at any time as to Shares that have not yet vested. Vested Shares shall not be subject to the
Company’s repurchase right (as set forth in the Restricted Stock Purchase Agreement, attached hereto as Exhibit C-1). 

(ii) As a condition to exercising this Option for unvested Shares, Participant shall execute the Restricted Stock Purchase Agreement. 

(iii) This Option may not be exercised for a fraction of a Share. 

  
 -2- 

 (b) Method of Exercise. This Option shall be exercisable by delivery of an exercise
notice in the form attached as Exhibit A (the “Exercise Notice”) or in a manner and pursuant to such procedures as the Administrator may determine, which shall state the election to exercise the Option, the number of Shares with
respect to which the Option is being exercised (the “Exercised Shares”), and such other representations and agreements as may be required by the Company. The Exercise Notice shall be accompanied by payment of the aggregate Exercise Price
as to all Exercised Shares, together with any applicable tax withholding. This Option shall be deemed to be exercised upon receipt by the Company of such fully executed Exercise Notice accompanied by the aggregate Exercise Price, together with any
applicable tax withholding. 
 No Shares shall be issued pursuant to the exercise of an Option unless such issuance and such exercise comply
with Applicable Laws. Assuming such compliance, for income tax purposes the Shares shall be considered transferred to Participant on the date on which the Option is exercised with respect to such Shares. 

3. Participant’s Representations. In the event the Shares have not been registered under the Securities Act of 1933, as amended
(the “Securities Act”), at the time this Option is exercised, Participant shall, if required by the Company, concurrently with the exercise of all or any portion of this Option, deliver to the Company his or her Investment Representation
Statement in the form attached hereto as Exhibit B. 
 4. Lock-Up
Period. Participant hereby agrees that Participant shall not offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or
otherwise transfer or dispose of, directly or indirectly, any Common Stock (or other securities) of the Company or enter into any swap, hedging or other arrangement that transfers to another, in whole or in part, any of the economic consequences of
ownership of any Common Stock (or other securities) of the Company held by Participant (other than those included in the registration) for a period specified by the representative of the underwriters of Common Stock (or other securities) of the
Company not to exceed one hundred and eighty (180) days following the effective date of any registration statement of the Company filed under the Securities Act (or such other period as may be requested by the Company or the underwriters to
accommodate regulatory restrictions on (i) the publication or other distribution of research reports and (ii) analyst recommendations and opinions, including, but not limited to, the restrictions contained in NASD Rule 2711(f)(4) or
NYSE Rule 472(f)(4), or any successor provisions or amendments thereto). 
 Participant agrees to execute and deliver such other
agreements as may be reasonably requested by the Company or the underwriter which are consistent with the foregoing or which are necessary to give further effect thereto. In addition, if requested by the Company or the representative of the
underwriters of Common Stock (or other securities) of the Company, Participant shall provide, within ten (10) days of such request, such information as may be required by the Company or such representative in connection with the completion of
any public offering of the Company’s securities pursuant to a registration statement filed under the Securities Act. The obligations described in this Section 4 shall not apply to a registration relating solely to employee benefit plans on
Form S-1 or Form S-8 or similar forms that may be promulgated in the future, or a registration relating solely to a Commission Rule 145 transaction on Form S-4 or similar forms that may be promulgated in the future. The Company may impose stop-transfer instructions with respect to the shares of Common Stock (or other securities) subject to the foregoing restriction
until the end of said one hundred and eighty (180) day (or other) period. Participant agrees that any transferee of the Option or shares acquired pursuant to the Option shall be bound by this Section 4. 

  
 -3- 

 5. Method of Payment. Payment of the aggregate Exercise Price shall be by any of the
following, or a combination thereof, at the election of the Participant: 
 (a) cash; 

(b) check; 
 (c) consideration
received by the Company under a formal cashless exercise program adopted by the Company in connection with the Plan; or 
 (d) surrender of
other Shares which (i) shall be valued at its Fair Market Value on the date of exercise, and (ii) must be owned free and clear of any liens, claims, encumbrances or security interests, if accepting such Shares, in the sole discretion of
the Administrator, shall not result in any adverse accounting consequences to the Company. 
 6. Restrictions on Exercise. This Option
may not be exercised until such time as the Plan has been approved by the stockholders of the Company, or if the issuance of such Shares upon such exercise or the method of payment of consideration for such shares would constitute a violation of any
Applicable Law. 
 7. Non-Transferability of Option. 

(a) This Option may not be transferred in any manner otherwise than by will or by the laws of descent or distribution and may be exercised
during the lifetime of Participant only by Participant. The terms of the Plan and this Option Agreement shall be binding upon the executors, administrators, heirs, successors and assigns of Participant. 

(b) Further, until the Company becomes subject to the reporting requirements of Section 13 or 15(d) of the Exchange Act, or after the
Administrator determines that it is, will, or may no longer be relying upon the exemption from registration of Options under the Exchange Act as set forth in Rule 12h-1(f) promulgated under the Exchange Act
(the “Reliance End Date”), Participant shall not transfer this Option or, prior to exercise, the Shares subject to this Option, in any manner other than (i) to persons who are “family members” (as defined in Rule 701(c)(3)
of the Securities Act) through gifts or domestic relations orders, or (ii) to an executor or guardian of Participant upon the death or disability of Participant. Until the Reliance End Date, the Options and, prior to exercise, the Shares
subject to this Option, may not be pledged, hypothecated or otherwise transferred or disposed of, including by entering into any short position, any “put equivalent position” or any “call equivalent position” (as defined in Rule 16a-1(h) and Rule 16a-1(b) of the Exchange Act, respectively), other than as permitted in clauses (i) and (ii) of this paragraph. 

8. Term of Option. This Option may be exercised only within the term set out in the Notice of Stock Option Grant, and may be exercised
during such term only in accordance with the Plan and the terms of this Option Agreement. 

  
 -4- 

 9. Tax Obligations. 

(a) Tax Withholding. Participant agrees to make appropriate arrangements with the Company (or the Parent or Subsidiary employing or
retaining Participant) for the satisfaction of all Federal, state, local and foreign income and employment tax withholding requirements applicable to the Option exercise. Participant acknowledges and agrees that the Company may refuse to honor the
exercise and refuse to deliver the Shares if such withholding amounts are not delivered at the time of exercise. 
 (b) Notice of
Disqualifying Disposition of ISO Shares. If the Option granted to Participant herein is an ISO, and if Participant sells or otherwise disposes of any of the Shares acquired pursuant to the ISO on or before the later of (i) the date two
(2) years after the Date of Grant, or (ii) the date one (1) year after the date of exercise, Participant shall immediately notify the Company in writing of such disposition. Participant agrees that Participant may be subject to income
tax withholding by the Company on the compensation income recognized by Participant. 
 (c) Code Section 409A.
Under Code Section 409A, an Option that vests after December 31, 2004 (or that vested on or prior to such date but which was materially modified after October 3, 2004) that was granted with a per Share exercise price that is
determined by the Internal Revenue Service (the “IRS”) to be less than the Fair Market Value of a Share on the date of grant (a “discount option”) may be considered “deferred compensation.” An Option that is a
“discount option” may result in (i) income recognition by Participant prior to the exercise of the Option, (ii) an additional twenty percent (20%) federal income tax, and (iii) potential penalty and interest charges. The
“discount option” may also result in additional state income, penalty and interest tax to the Participant. Participant acknowledges that the Company cannot and has not guaranteed that the IRS will agree that the per Share exercise price of
this Option equals or exceeds the Fair Market Value of a Share on the date of grant in a later examination. Participant agrees that if the IRS determines that the Option was granted with a per Share exercise price that was less than the Fair Market
Value of a Share on the date of grant, Participant shall be solely responsible for Participant’s costs related to such a determination. 

10. Entire Agreement; Governing Law. The Plan is incorporated herein by reference. The Plan and this Option Agreement constitute the
entire agreement of the parties with respect to the subject matter hereof and supersede in their entirety all prior undertakings and agreements of the Company and Participant with respect to the subject matter hereof, and may not be modified
adversely to the Participant’s interest except by means of a writing signed by the Company and Participant. This Option Agreement is governed by the internal substantive laws but not the choice of law rules of California. 

11. No Guarantee of Continued Service. PARTICIPANT ACKNOWLEDGES AND AGREES THAT THE VESTING OF SHARES PURSUANT TO THE VESTING SCHEDULE
HEREOF IS EARNED ONLY BY CONTINUING AS A SERVICE PROVIDER AT THE WILL OF THE COMPANY (OR THE PARENT OR SUBSIDIARY EMPLOYING OR RETAINING PARTICIPANT) AND NOT THROUGH THE ACT OF BEING HIRED, BEING GRANTED THIS OPTION OR ACQUIRING SHARES HEREUNDER.
PARTICIPANT FURTHER ACKNOWLEDGES AND AGREES THAT THIS AGREEMENT, THE TRANSACTIONS CONTEMPLATED HEREUNDER AND THE VESTING SCHEDULE SET FORTH HEREIN DO 

  
 -5- 

 
NOT CONSTITUTE AN EXPRESS OR IMPLIED PROMISE OF CONTINUED ENGAGEMENT AS A SERVICE PROVIDER FOR THE VESTING PERIOD, FOR ANY PERIOD, OR AT ALL, AND SHALL NOT INTERFERE IN ANY WAY WITH
PARTICIPANT’S RIGHT OR THE RIGHT OF THE COMPANY (OR THE PARENT OR SUBSIDIARY EMPLOYING OR RETAINING PARTICIPANT) TO TERMINATE PARTICIPANT’S RELATIONSHIP AS A SERVICE PROVIDER AT ANY TIME, WITH OR WITHOUT CAUSE. 

Participant acknowledges receipt of a copy of the Plan and represents that he or she is familiar with the terms and provisions thereof, and
hereby accepts this Option subject to all of the terms and provisions thereof. Participant has reviewed the Plan and this Option in their entirety, has had an opportunity to obtain the advice of counsel prior to executing this Option and fully
understands all provisions of the Option. Participant hereby agrees to accept as binding, conclusive and final all decisions or interpretations of the Administrator upon any questions arising under the Plan or this Option. Participant further agrees
to notify the Company upon any change in the residence address indicated below. 
  

					
	PARTICIPANT	 		 	HARPOON THERAPEUTICS, INC.
			
	  
	 		 	  

	Signature	 		 	By
			
	  
	 		 	  

	Print Name	 		 	Print Name
			
	  
	 		 	  

		 		 	Title
			
	Residence Address:	 		 	
			
	  
	 		 	
			
	  
	 		 	

  

  
 -6- 

 EXHIBIT A 

2015 EQUITY INCENTIVE PLAN 

EXERCISE NOTICE 
 Harpoon Therapeutics,
Inc. 

                          
               

                          
               
 Attention: President 

1. Exercise of Option. Effective as of today,
                            ,         , the undersigned
(“Participant”) hereby elects to exercise Participant’s option (the “Option”) to purchase
                            shares of the Common Stock (the “Shares”) of Harpoon Therapeutics, Inc.
(the “Company”) under and pursuant to the 2015 Equity Incentive Plan (the “Plan”) and the Stock Option Agreement – Early Exercise dated
                         (the “Option Agreement”). 

2. Delivery of Payment. Participant herewith delivers to the Company the full purchase price of the Shares, as set forth in the Option
Agreement, and any and all withholding taxes due in connection with the exercise of the Option. 
 3. Representations of Participant.
Participant acknowledges that Participant has received, read and understood the Plan and the Option Agreement and agrees to abide by and be bound by their terms and conditions. 

4. Rights as Stockholder. Until the issuance of the Shares (as evidenced by the appropriate entry on the books of the Company or of a
duly authorized transfer agent of the Company), no right to vote or receive dividends or any other rights as a stockholder shall exist with respect to the Common Stock subject to an Award, notwithstanding the exercise of the Option. The Shares shall
be issued to Participant as soon as practicable after the Option is exercised in accordance with the Option Agreement. No adjustment shall be made for a dividend or other right for which the record date is prior to the date of issuance except as
provided in Section 13 of the Plan. 
 5. Company’s Right of First Refusal. Before any Shares held by Participant or any
transferee (either being sometimes referred to herein as the “Holder”) may be sold or otherwise transferred (including transfer by gift or operation of law), the Company or its assignee(s) shall have a right of first refusal to purchase
the Shares on the terms and conditions set forth in this Section 5 (the “Right of First Refusal”). 
 (a) Notice of
Proposed Transfer. The Holder of the Shares shall deliver to the Company a written notice (the “Notice”) stating: (i) the Holder’s bona fide intention to sell or otherwise transfer such Shares; (ii) the name of each
proposed purchaser or other transferee (“Proposed Transferee”); (iii) the number of Shares to be transferred to each Proposed Transferee; and (iv) the bona fide cash price or other consideration for which the Holder proposes to
transfer the Shares (the “Offered Price”), and the Holder shall offer the Shares at the Offered Price to the Company or its assignee(s). 

 (b) Exercise of Right of First Refusal. At any time within thirty (30) days
after receipt of the Notice, the Company and/or its assignee(s) may, by giving written notice to the Holder, elect to purchase all, but not less than all, of the Shares proposed to be transferred to any one or more of the Proposed Transferees, at
the purchase price determined in accordance with subsection (c) below. 
 (c) Purchase Price. The purchase price (“Purchase
Price”) for the Shares purchased by the Company or its assignee(s) under this Section 5 shall be the Offered Price. If the Offered Price includes consideration other than cash, the cash equivalent value of the non-cash consideration shall be determined by the Board of Directors of the Company in good faith. 
 (d)
Payment. Payment of the Purchase Price shall be made, at the option of the Company or its assignee(s), in cash (by check), by cancellation of all or a portion of any outstanding indebtedness of the Holder to the Company (or, in the case of
repurchase by an assignee, to the assignee), or by any combination thereof within thirty (30) days after receipt of the Notice or in the manner and at the times set forth in the Notice. 

(e) Holder’s Right to Transfer. If all of the Shares proposed in the Notice to be transferred to a given Proposed Transferee are
not purchased by the Company and/or its assignee(s) as provided in this Section 5, then the Holder may sell or otherwise transfer such Shares to that Proposed Transferee at the Offered Price or at a higher price, provided that such sale or
other transfer is consummated within one hundred and twenty (120) days after the date of the Notice, that any such sale or other transfer is effected in accordance with any applicable securities laws and that the Proposed Transferee agrees in
writing that the provisions of this Section 5 shall continue to apply to the Shares in the hands of such Proposed Transferee. If the Shares described in the Notice are not transferred to the Proposed Transferee within such period, a new Notice
shall be given to the Company, and the Company and/or its assignees shall again be offered the Right of First Refusal before any Shares held by the Holder may be sold or otherwise transferred. 

(f) Exception for Certain Family Transfers. Anything to the contrary contained in this Section 5 notwithstanding, the transfer of
any or all of the Shares during the Participant’s lifetime or on the Participant’s death by will or intestacy to the Participant’s immediate family or a trust for the benefit of the Participant’s immediate family shall be exempt
from the provisions of this Section 5. “Immediate Family” as used herein shall mean spouse, lineal descendant or antecedent, father, mother, brother or sister. In such case, the transferee or other recipient shall receive and hold the
Shares so transferred subject to the provisions of this Section 5, and there shall be no further transfer of such Shares except in accordance with the terms of this Section 5. 

(g) Termination of Right of First Refusal. The Right of First Refusal shall terminate as to any Shares upon the earlier of (i) the
first sale of Common Stock of the Company to the general public, or (ii) a Change in Control in which the successor corporation has equity securities that are publicly traded. 

6. Tax Consultation. Participant understands that Participant may suffer adverse tax consequences as a result of Participant’s
purchase or disposition of the Shares. Participant represents that Participant has consulted with any tax consultants Participant deems advisable in connection with the purchase or disposition of the Shares and that Participant is not relying on the
Company for any tax advice. 

  
 -2- 

 7. Restrictive Legends and Stop-Transfer Orders. 

(a) Legends. Participant understands and agrees that the Company shall cause the legends set forth below or legends substantially
equivalent thereto, to be placed upon any certificate(s) evidencing ownership of the Shares together with any other legends that may be required by the Company or by state or federal securities laws: 

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 (THE “ACT”) AND MAY NOT BE OFFERED, SOLD
OR OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED UNLESS AND UNTIL REGISTERED UNDER THE ACT OR, IN THE OPINION OF COUNSEL SATISFACTORY TO THE ISSUER OF THESE SECURITIES, SUCH OFFER, SALE OR TRANSFER, PLEDGE OR HYPOTHECATION IS IN COMPLIANCE
THEREWITH. 
 THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO CERTAIN RESTRICTIONS ON TRANSFER AND A RIGHT OF FIRST REFUSAL HELD BY
THE ISSUER OR ITS ASSIGNEE(S) AS SET FORTH IN THE EXERCISE NOTICE BETWEEN THE ISSUER AND THE ORIGINAL HOLDER OF THESE SHARES, A COPY OF WHICH MAY BE OBTAINED AT THE PRINCIPAL OFFICE OF THE ISSUER. SUCH TRANSFER RESTRICTIONS AND RIGHT OF FIRST
REFUSAL ARE BINDING ON TRANSFEREES OF THESE SHARES. 
 THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO RESTRICTIONS ON TRANSFER FOR
A PERIOD OF TIME FOLLOWING THE EFFECTIVE DATE OF THE UNDERWRITTEN PUBLIC OFFERING OF THE COMPANY’S SECURITIES SET FORTH IN AN AGREEMENT BETWEEN THE ISSUER AND THE ORIGINAL HOLDER OF THESE SHARES AND MAY NOT BE SOLD OR OTHERWISE DISPOSED OF BY
THE HOLDER PRIOR TO THE EXPIRATION OF SUCH PERIOD WITHOUT THE CONSENT OF THE COMPANY OR THE MANAGING UNDERWRITER. 
 (b) Stop-Transfer
Notices. Participant agrees that, in order to ensure compliance with the restrictions referred to herein, the Company may issue appropriate “stop transfer” instructions to its transfer agent, if any, and that, if the Company transfers
its own securities, it may make appropriate notations to the same effect in its own records. 
 (c) Refusal to Transfer. The
Company shall not be required (i) to transfer on its books any Shares that have been sold or otherwise transferred in violation of any of the provisions of this Exercise Notice or (ii) to treat as owner of such Shares or to accord the
right to vote or pay dividends to any purchaser or other transferee to whom such Shares shall have been so transferred. 

  
 -3- 

 8. Successors and Assigns. The Company may assign any of its rights under this
Exercise Notice to single or multiple assignees, and this Exercise Notice shall inure to the benefit of the successors and assigns of the Company. Subject to the restrictions on transfer herein set forth, this Exercise Notice shall be binding upon
Participant and his or her heirs, executors, administrators, successors and assigns. 
 9. Interpretation. Any dispute regarding the
interpretation of this Exercise Notice shall be submitted by Participant or by the Company forthwith to the Administrator, which shall review such dispute at its next regular meeting. The resolution of such a dispute by the Administrator shall be
final and binding on all parties. 
 10. Governing Law; Severability. This Exercise Notice is governed by the internal substantive
laws, but not the choice of law rules, of California. In the event that any provision hereof becomes or is declared by a court of competent jurisdiction to be illegal, unenforceable or void, this Exercise Notice shall continue in full force and
effect. 
 11. Entire Agreement. The Plan and Option Agreement are incorporated herein by reference. This Exercise Notice, the Plan,
the Restricted Stock Purchase Agreement, the Option Agreement and the Investment Representation Statement constitute the entire agreement of the parties with respect to the subject matter hereof and supersede in their entirety all prior undertakings
and agreements of the Company and Participant with respect to the subject matter hereof, and may not be modified adversely to the Participant’s interest except by means of a writing signed by the Company and Participant. 

 

					
	Submitted by:	 		  	Accepted by:
	PARTICIPANT	 		  	HARPOON THERAPEUTICS, INC.
			
	  
	 		  	  

	Signature	 		  	By
			
	  
	 		  	  

	Print Name	 		  	Print Name
			
		 		  	  

		 		  	Title
			
	Address:	 		  	Address:
			
	  
	 		  	  

			
	  
	 		  	  

			
		 		  	  

		 		  	Date Received

  
 -4- 

 EXHIBIT B 

INVESTMENT REPRESENTATION STATEMENT 
  

					
	PARTICIPANT	  	:	  	                                      
          
		  		  	
	COMPANY	  	:	  	HARPOON THERAPEUTICS, INC.
			
	SECURITY	  	:	  	COMMON STOCK
			
	AMOUNT	  	:	  	                                      
           
		  		  	
	DATE	  	:	  	
                          
                      

 In connection with the purchase of the above-listed Securities, the undersigned
Participant represents to the Company the following: 
 (a) Participant is aware of the Company’s business affairs and financial
condition and has acquired sufficient information about the Company to reach an informed and knowledgeable decision to acquire the Securities. Participant is acquiring these Securities for investment for Participant’s 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 of 1933, as amended (the “Securities Act”). 

(b) Participant acknowledges and understands that the Securities constitute “restricted securities” under the Securities Act and have
not been registered under the Securities Act in reliance upon a specific exemption therefrom, which exemption depends upon, among other things, the bona fide nature of Participant’s investment intent as expressed herein. In this connection,
Participant understands that, in the view of the Securities and Exchange Commission, the statutory basis for such exemption may be unavailable if Participant’s representation was predicated solely upon a present intention to hold these
Securities for the minimum capital gains period specified under tax statutes, for a deferred sale, for or until an increase or decrease in the market price of the Securities, or for a period of one (1) year or any other fixed period in the
future. Participant further understands that the Securities must be held indefinitely unless they are subsequently registered under the Securities Act or an exemption from such registration is available. Participant further acknowledges and
understands that the Company is under no obligation to register the Securities. Participant understands that the certificate evidencing the Securities shall be imprinted with any legend required under applicable state securities laws. 

(c) Participant is familiar with the provisions of Rule 701 and Rule 144, each promulgated under the Securities Act, which, in
substance, permit limited public resale of “restricted securities” acquired, directly or indirectly from the issuer thereof, in a non-public offering subject to the satisfaction of certain
conditions. Rule 701 provides that if the issuer qualifies under Rule 701 at the time of the grant of the Option to Participant, the exercise shall be exempt from registration under the Securities Act. In the event the Company becomes
subject to the reporting requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, ninety (90) days thereafter (or such longer period as any market stand-off agreement may require)
the Securities exempt under Rule 701 

 
may be resold, subject to the satisfaction of the applicable conditions specified by Rule 144, including in the case of affiliates (1) the availability of certain public information
about the Company, (2) the amount of Securities being sold during any three (3) month period not exceeding specified limitations, (3) the resale being made in an unsolicited “broker’s transaction”, transactions directly
with a “market maker” or “riskless principal transactions” (as those terms are defined under the Securities Exchange Act of 1934) and (4) the timely filing of a Form 144, if applicable. 

In the event that the Company does not qualify under Rule 701 at the time of grant of the Option, then the Securities may be resold in
certain limited circumstances subject to the provisions of Rule 144, which may require (i) the availability of current public information about the Company; (ii) the resale to occur more than a specified period after the purchase and
full payment (within the meaning of Rule 144) for the Securities; and (iii) in the case of the sale of Securities by an affiliate, the satisfaction of the conditions set forth in sections (2), (3) and (4) of the paragraph
immediately above. 
 (d) Participant further understands that in the event all of the applicable requirements of Rule 701 or 144 are
not satisfied, registration under the Securities Act, compliance with Regulation A, or some other registration exemption shall be required; and that, notwithstanding the fact that Rules 144 and 701 are not exclusive, the Staff of the Securities and
Exchange Commission has expressed its opinion that persons proposing to sell private placement securities other than in a registered offering and otherwise than pursuant to Rules 144 or 701 shall have a substantial burden of proof in establishing
that an exemption from registration is available for such offers or sales, and that such persons and their respective brokers who participate in such transactions do so at their own risk. Participant understands that no assurances can be given that
any such other registration exemption shall be available in such event. 
  

	
	PARTICIPANT
	
	  

	Signature
	
	  

	Print Name
	
	  

	Date

  
 -2- 

 EXHIBIT C-1 

HARPOON THERAPEUTICS, INC. 

2015 EQUITY INCENTIVE PLAN 

RESTRICTED STOCK PURCHASE AGREEMENT 

THIS RESTRICTED STOCK PURCHASE AGREEMENT (the “Agreement”) is made
between                     (the “Purchaser”) and Harpoon Therapeutics, Inc. (the “Company”) or its assignees of rights hereunder
as of                     ,                     .

 Unless otherwise defined herein, the terms defined in the 2015 Equity Incentive Plan shall have the same defined meanings in this
Agreement. 
 RECITALS 

A. Pursuant to the exercise of the option (grant number             ) granted to
Purchaser under the Plan and pursuant to the Stock Option Agreement – Early Exercise (the “Option Agreement”) dated
                                         by and
between the Company and Purchaser with respect to such grant (the “Option”), which Plan and Option Agreement are hereby incorporated by reference, Purchaser has elected to purchase
                         of those shares of Common Stock which have not become vested under the vesting schedule set forth in the
Option Agreement (“Unvested Shares”). The Unvested Shares and the shares subject to the Option Agreement, which have become vested are sometimes collectively referred to herein as the “Shares.” 

B. As required by the Option Agreement, as a condition to Purchaser’s election to exercise the option, Purchaser must execute this
Agreement, which sets forth the rights and obligations of the parties with respect to Shares acquired upon exercise of the Option. 
 1.
Repurchase Option. 
 (a) If Purchaser’s status as a Service Provider is terminated for any reason, including for death and
Disability, the Company shall have the irrevocable and exclusive right and option to purchase from Purchaser, or Purchaser’s personal representative, as the case may be, all of the Purchaser’s Unvested Shares as of the date of such
termination at the price paid by the Purchaser for such Shares (the “Repurchase Option”). The Company may exercise its Repurchase Option as to any or all of the Unreleased Shares at any time after the Purchaser ceases to be a Service
Provider; provided, however, that without requirement of further action on the part of either party hereto, the Repurchase Option shall be deemed to have been automatically exercised as to all Unreleased Shares at 5:00 p.m. (Pacific Time) as
of the date that is 60 days following the date the Purchaser ceases to be a Service Provider, unless the Company declines in writing to exercise its Repurchase Option prior to such time. 

 (b) If the Company decides not to exercise its Repurchase Option, it shall notify the
Purchaser in writing within 60 days of the date the Purchaser ceases to be a Service Provider. If the Repurchase Option is exercised or deemed exercised, within 90 days of the date the Purchaser ceases to be a Service Provider, the Company shall
deliver payment to the Purchaser, with a copy to the escrow agent described in Section 2 hereof, by any of the following methods, in the Company’s sole discretion: (i) delivering to the Purchaser or the Purchaser’s executor a
check in the amount of the aggregate repurchase price, (ii) canceling an amount of the Purchaser’s indebtedness to the Company equal to the aggregate repurchase price, or (iii) any combination of (i) and (ii) such that the
combined payment and cancellation of indebtedness equals the aggregate repurchase price. 
 (c) The Company in its sole discretion may assign
all or part of the Repurchase Option to one or more employees, officers, directors or stockholders of the Company or other persons or organizations. 

(d) In the event that the Repurchase Option is exercised or deemed exercised, the sole right and remedy of the Purchaser thereafter shall be to
receive the repurchase price, and in no case shall the Purchaser have any claim of ownership as to any of the Unreleased Shares. 
 (e) The
Repurchase Option shall terminate in accordance with the vesting schedule contained in Purchaser’s Option Agreement. 
 2.
Transferability of the Shares; Escrow. 
 (a) Purchaser hereby authorizes and directs the Secretary of the Company, or such other
person designated by the Company, to transfer the Unvested Shares as to which the Repurchase Option has been exercised from Purchaser to the Company. 

(b) To insure the availability for delivery of Purchaser’s Unvested Shares upon repurchase by the Company pursuant to the Repurchase
Option under Section 1, Purchaser hereby appoints the Secretary, or any other person designated by the Company as escrow agent (the “Escrow Agent”), as its
attorney-in-fact to sell, assign and transfer unto the Company, such Unvested Shares, if any, repurchased by the Company pursuant to the Repurchase Option and shall,
upon execution of this Agreement, deliver and deposit with the Escrow Agent, the share certificates representing the Unvested Shares, together with the stock assignment duly endorsed in blank, attached hereto as Exhibit C-2. The Unvested Shares and stock assignment shall be held by the Escrow Agent in escrow, pursuant to the Joint Escrow Instructions of the Company and Purchaser attached as Exhibit C-3 hereto, until the Company exercises its Repurchase Option, until such Unvested Shares are vested, or until such time as this Agreement no longer is in effect. Upon vesting of the Unvested Shares, the Escrow
Agent shall promptly deliver to the Purchaser the certificate or certificates representing such Shares in the Escrow Agent’s possession belonging to the Purchaser, and the Escrow Agent shall be discharged of all further obligations hereunder;
provided, however, that the Escrow Agent shall nevertheless retain such certificate or certificates as Escrow Agent if so required pursuant to other restrictions imposed pursuant to this Agreement. 

(c) Neither the Company nor the Escrow Agent shall be liable for any act it may do or omit to do with respect to holding the Shares in escrow
and while acting in good faith and in the exercise of its judgment. 

  
 -2- 

 (d) Transfer or sale of the Shares is subject to restrictions on transfer imposed by any
applicable state and federal securities laws. Any transferee shall hold such Shares subject to all the provisions hereof and the Exercise Notice executed by the Purchaser with respect to any Unvested Shares purchased by Purchaser and shall
acknowledge the same by signing a copy of this Agreement. 
 3. Ownership, Voting Rights, Duties. This Agreement shall not affect in
any way the ownership, voting rights or other rights or duties of Purchaser, except as specifically provided herein. 
 4. Legends.
The share certificate evidencing the Shares issued hereunder shall be endorsed with the following legend (in addition to any legend required under applicable federal and state securities laws): 

THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO CERTAIN RESTRICTIONS UPON TRANSFER AND RIGHTS OF REPURCHASE AS SET FORTH IN AN
AGREEMENT BETWEEN THE COMPANY AND THE STOCKHOLDER, A COPY OF WHICH IS ON FILE WITH THE SECRETARY OF THE COMPANY. 
 5. Adjustment for
Stock Split. All references to the number of Shares and the purchase price of the Shares in this Agreement shall be appropriately adjusted to reflect any stock split, stock dividend or other change in the Shares, which may be made by the Company
pursuant to Section 9 of the Plan after the date of this Agreement. 
 6. Notices. Notices required hereunder shall be given in
person or by registered mail to the address of Purchaser shown on the records of the Company, and to the Company at their respective principal executive offices. 

7. Survival of Terms. This Agreement shall apply to and bind Purchaser and the Company and their respective permitted assignees and
transferees, heirs, legatees, executors, administrators and legal successors. 
 8. Section 83(b) Election. Purchaser hereby
acknowledges that he or she has been informed that, with respect to the exercise of an Option for Unvested Shares, an election (the “Election”) may be filed by the Purchaser with the Internal Revenue Service, within thirty (30) days
of the purchase of the exercised Shares, electing pursuant to Section 83(b) of the Code to be taxed currently on any difference between the purchase price of the exercised Shares and their Fair Market Value on the date of purchase. In the case
of a Nonstatutory Stock Option, this will result in the recognition of taxable income to the Purchaser on the date of exercise, measured by the excess, if any, of the Fair Market Value of the exercised Shares, at the time the Option is exercised
over the purchase price for the exercised Shares. Absent such an Election, taxable income will be measured and recognized by Purchaser at the time or times on which the Company’s Repurchase Option lapses. In the case of an Incentive Stock
Option, such an Election will result in a recognition of income to the Purchaser for alternative minimum tax purposes on the date of exercise, measured by the excess, if any, of the Fair Market Value of the exercised Shares, at the time the option
is exercised, over the purchase price for the exercised Shares. Absent such an Election, alternative minimum taxable income will be measured and recognized by Purchaser at the time or times on which the Company’s Repurchase Option lapses. 

  
 -3- 

 This discussion is intended only as a summary of the general United States income tax laws
that apply to exercising Options as to Shares that have not yet vested and is accurate only as of the date this form Agreement was approved by the Board. The federal, state and local tax consequences to any particular taxpayer will depend upon his
or her individual circumstances. Purchaser is strongly encouraged to seek the advice of his or her own tax consultants in connection with the purchase of the Shares and the advisability of filing of the Election under Section 83(b) of the Code.
A form of Election under Section 83(b) is attached hereto as Exhibit C-4 for reference. 

PURCHASER ACKNOWLEDGES THAT IT IS PURCHASER’S SOLE RESPONSIBILITY AND NOT THE COMPANY’S TO FILE TIMELY THE ELECTION UNDER
SECTION 83(b) OF THE CODE, EVEN IF PURCHASER REQUESTS THE COMPANY OR ITS REPRESENTATIVE TO MAKE THIS FILING ON PURCHASER’S BEHALF. 

9. Representations. Purchaser has reviewed with his or her own tax advisors the federal, state, local and foreign tax consequences of
this investment and the transactions contemplated by this Agreement. Purchaser is relying solely on such advisors and not on any statements or representations of the Company or any of its agents. Purchaser understands that he or she (and not the
Company) shall be responsible for his or her own tax liability that may arise as a result of this investment or the transactions contemplated by this Agreement. 

10. Investment Decision. Participant understands and acknowledges that by early exercising the Option, Participant is choosing to invest
in the Company earlier than necessary and is accepting the risk that such investment may lose some or all of its value. Participant also understands and acknowledges that Participant can reduce the risk of investment loss by delaying exercising the
Option until Participant has better insight into the Company’s business prospects. 
 11. Entire Agreement; Governing Law. The
Plan and Option Agreement are incorporated herein by reference. The Plan, the Option Agreement, the Exercise Notice, this Agreement, and the Investment Representation Statement constitute the entire agreement of the parties with respect to the
subject matter hereof and supersede in their entirety all prior undertakings and agreements of the Company and Purchaser with respect to the subject matter hereof, and may not be modified adversely to the Purchaser’s interest except by means of
a writing signed by the Company and Purchaser. This Agreement is governed by the internal substantive laws but not the choice of law rules of California. 

Purchaser represents that he or she has read this Agreement and is familiar with its terms and provisions. Purchaser hereby agrees to accept
as binding, conclusive and final all decisions or interpretations of the Board upon any questions arising under this Agreement. 

  
 -4- 

 IN WITNESS WHEREOF, this Agreement is deemed made as of the date first set forth above. 

 

					
	PARTICIPANT	 		  	HARPOON THERAPEUTICS, INC.
			
	  
	 		  	  

	Signature	 		  	By
			
	  
	 		  	  

	Print Name	 		  	Print Name
			
		 		  	  

	  
	 		  	Title
	Residence Address	 		  	
			
	Dated:
                                        ,
            	 		  	

  
 -5- 

 EXHIBIT C-2 

ASSIGNMENT SEPARATE FROM CERTIFICATE 

FOR VALUE RECEIVED I,
                                         , hereby
sell, assign and transfer unto Harpoon Therapeutics, Inc.
                                     shares of the Common Stock of
Harpoon Therapeutics, Inc. standing in my name of the books of said corporation represented by Certificate No.                  herewith and do hereby irrevocably
constitute and appoint
                                         to
transfer the said stock on the books of the within named corporation with full power of substitution in the premises. 
 This Stock
Assignment may be used only in accordance with the Restricted Stock Purchase Agreement between Harpoon Therapeutics, Inc. and the undersigned dated
                                         (the
“Agreement”). 
  

			
	Dated:                                  ,
                	  	Signature:                                    
                        

 INSTRUCTIONS: Please do not fill in any blanks other than the signature line. The purpose of this assignment
is to enable the Company to exercise its “repurchase option,” as set forth in the Agreement, without requiring additional signatures on the part of the Purchaser. 

 EXHIBIT C-3 

JOINT ESCROW INSTRUCTIONS 

                       
                  ,                  

Corporate Secretary 

                          
                       

                          
                       

                          
                       
 Dear
                             : 

As Escrow Agent for both Harpoon Therapeutics, Inc. (the “Company”), and the undersigned purchaser of stock of the Company (the
“Purchaser”), you are hereby authorized and directed to hold the documents delivered to you pursuant to the terms of that certain Restricted Stock Purchase Agreement (the “Agreement”) between the Company and the undersigned, in
accordance with the following instructions: 
 1. In the event the Company and/or any assignee of the Company (referred to collectively for
convenience herein as the “Company”) exercises the Company’s repurchase option set forth in the Agreement, the Company shall give to Purchaser and you a written notice specifying the number of shares of stock to be purchased, the
purchase price, and the time for a closing hereunder at the principal office of the Company. Purchaser and the Company hereby irrevocably authorize and direct you to close the transaction contemplated by such notice in accordance with the terms of
said notice. 
 2. At the closing, you are directed (a) to date the stock assignments necessary for the transfer in question,
(b) to fill in the number of shares being transferred, and (c) to deliver the stock assignments, together with the certificate evidencing the shares of stock to be transferred, to the Company or its assignee, against the simultaneous
delivery to you of the purchase price (by cash, a check, or some combination thereof) for the number of shares of stock being purchased pursuant to the exercise of the Company’s repurchase option. 

3. Purchaser irrevocably authorizes the Company to deposit with you any certificates evidencing shares of stock to be held by you hereunder and
any additions and substitutions to said shares as defined in the Agreement. Purchaser does hereby irrevocably constitute and appoint you as Purchaser’s
attorney-in-fact and agent for the term of this escrow to execute with respect to such securities all documents necessary or appropriate to make such securities
negotiable and to complete any transaction herein contemplated, including but not limited to the filing with any applicable state blue sky authority of any required applications for consent to, or notice of transfer of, the securities. Subject to
the provisions of this paragraph 3, Purchaser shall exercise all rights and privileges of a stockholder of the Company while the stock is held by you. 

 4. Upon written request of the Purchaser, but no more than once per calendar year, unless
the Company’s repurchase option has been exercised, you shall deliver to Purchaser a certificate or certificates representing so many shares of stock as are not then subject to the Company’s repurchase option. Within one hundred and twenty
(120) days after cessation of Purchaser’s continuous employment by or services to the Company, or any parent or subsidiary of the Company, you shall deliver to Purchaser a certificate or certificates representing the aggregate number of
shares held or issued pursuant to the Agreement and not purchased by the Company or its assignees pursuant to exercise of the Company’s repurchase option. 

5. If at the time of termination of this escrow you should have in your possession any documents, securities, or other property belonging to
Purchaser, you shall deliver all of the same to Purchaser and shall be discharged of all further obligations hereunder. 
 6. Your duties
hereunder may be altered, amended, modified or revoked only by a writing signed by all of the parties hereto. 
 7. You shall be obligated
only for the performance of such duties as are specifically set forth herein and may rely and shall be protected in relying or refraining from acting on any instrument reasonably believed by you to be genuine and to have been signed or presented by
the proper party or parties. You shall not be personally liable for any act you may do or omit to do hereunder as Escrow Agent or as attorney-in-fact for Purchaser while
acting in good faith, and any act done or omitted by you pursuant to the advice of your own attorneys shall be conclusive evidence of such good faith. 

8. You are hereby expressly authorized to disregard any and all warnings given by any of the parties hereto or by any other person or
corporation, excepting only orders or process of courts of law and are hereby expressly authorized to comply with and obey orders, judgments or decrees of any court. In case you obey or comply with any such order, judgment or decree, you shall not
be liable to any of the parties hereto or to any other person, firm or corporation by reason of such compliance, notwithstanding any such order, judgment or decree being subsequently reversed, modified, annulled, set aside, vacated or found to have
been entered without jurisdiction. 
 9. You shall not be liable in any respect on account of the identity, authorities or rights of the
parties executing or delivering or purporting to execute or deliver the Agreement or any documents or papers deposited or called for hereunder. 

10. You shall not be liable for the outlawing of any rights under the Statute of Limitations with respect to these Joint Escrow Instructions or
any documents deposited with you. 
 11. You shall be entitled to employ such legal counsel and other experts as you may deem necessary
properly to advise you in connection with your obligations hereunder, may rely upon the advice of such counsel, and may pay such counsel reasonable compensation therefor. 

12. Your responsibilities as Escrow Agent hereunder shall terminate if you shall cease to be an officer or agent of the Company or if you shall
resign by written notice to each party. In the event of any such termination, the Company shall appoint a successor Escrow Agent. 
 13. If
you reasonably require other or further instruments in connection with these Joint Escrow Instructions or obligations in respect hereto, the necessary parties hereto shall join in furnishing such instruments. 

  
 -2- 

 14. It is understood and agreed that should any dispute arise with respect to the delivery
and/or ownership or right of possession of the securities held by you hereunder, you are authorized and directed to retain in your possession without liability to anyone all or any part of said securities until such disputes shall have been settled
either by mutual written agreement of the parties concerned or by a final order, decree or judgment of a court of competent jurisdiction after the time for appeal has expired and no appeal has been perfected, but you shall be under no duty
whatsoever to institute or defend any such proceedings. 
 15. Any notice required or permitted hereunder shall be given in writing and shall
be deemed effectively given upon personal delivery or upon deposit in the United States Post Office, by registered or certified mail with postage and fees prepaid, addressed to each of the other parties thereunto entitled at the following addresses
or at such other addresses as a party may designate by ten (10) days’ advance written notice to each of the other parties hereto. 

16. By signing these Joint Escrow Instructions, you become a party hereto only for the purpose of said Joint Escrow Instructions; you do not
become a party to the Agreement. 
 17. This instrument shall be binding upon and inure to the benefit of the parties hereto, and their
respective successors and permitted assigns. 
 18. These Joint Escrow Instructions shall be governed by the internal substantive laws, but
not the choice of law rules, of California. 
  

					
	PURCHASER	 		 	HARPOON THERAPEUTICS, INC.
			
	  
 Signature
	 		 	  
 By

			
	  
 Print Name
	 		 	  
 Print Name

			
	  
	 		 	  

	  
	 		 	Title
	Residence Address	 		 	
			
	ESCROW AGENT	 		 	
			
	  
 Corporate Secretary
	 		 	
			
	Dated:
                                         
                                         
      	 		 	

  
 -3- 

 EXHIBIT C-4 

ELECTION UNDER SECTION 83(b) 

OF THE INTERNAL REVENUE CODE OF 1986 
 The
undersigned taxpayer hereby elects, pursuant to Sections 55 and 83(b) of the Internal Revenue Code of 1986, as amended, to include in taxpayer’s gross income or alternative minimum taxable income, as the case may be, for the current taxable
year the amount of any compensation taxable to taxpayer in connection with taxpayer’s receipt of the property described below. 
  

	1.	 The name, address, taxpayer identification number and taxable year of the undersigned are as follows:

  

					
		  	TAXPAYER	  	SPOUSE
	NAME:	  	  
	  	  

	ADDRESS:	  	  
	  	
		  	  
	  	
	TAX ID NO.:	  	  
	  	  

	TAXABLE YEAR:	  	20      	  	

  

	2.	 The property with respect to which the election is made is described as follows:
                     shares (the “Shares”) of the Common Stock of Harpoon Therapeutics, Inc. (the “Company”).

  

	3.	 The date on which the property was transferred
is:                            
,                . 

  

	4.	 The property is subject to the following restrictions: 

The Shares may not be transferred and are subject to forfeiture under the terms of an agreement between the taxpayer and the Company. These
restrictions lapse upon the satisfaction of certain conditions contained in such agreement. 
  

	5.	 The Fair Market Value at the time of transfer, determined without regard to any restriction other than a
restriction which by its terms shall never lapse, of such property is:
$                                        .

  

	6.	 The amount (if any) paid for such property is:
$                                    . 

The undersigned has submitted a copy of this statement to the person for whom the services were performed in connection with the undersigned’s receipt of
the above-described property. The transferee of such property is the person performing the services in connection with the transfer of said property. 

The undersigned understands that the foregoing election may not be revoked except with the consent of the Commissioner. 

 

			
	Dated:                             ,
            	  	  

		  	        Taxpayer
	The undersigned spouse of taxpayer joins in this election.	  	
	Dated:                             ,
            	  	  

		  	        Spouse of Taxpayer

 HARPOON THERAPEUTICS, INC. 

2015 EQUITY INCENTIVE PLAN 

STOCK OPTION AGREEMENT 

Unless otherwise defined herein, the terms defined in the 2015 Equity Incentive Plan (the “Plan”) shall have the same defined
meanings in this Stock Option Agreement (the “Option Agreement”). 
  

	I.	 NOTICE OF STOCK OPTION GRANT 

 

			
	    Name:	  	  

		
	    Address:	  	  

 The undersigned Participant has been granted an Option to purchase Common Stock of the Company, subject to the
terms and conditions of the Plan and this Option Agreement, as follows: 
  

	 	Date	 of Grant: 

Vesting Commencement Date: 

Exercise Price per Share: 
 Total
Number of Shares Granted: 
 Total Exercise Price: 
  

			
	 Type of Option:
	  	                     Incentive Stock Option
		
		  	                     Nonstatutory Stock Option

  

	
	 Term/Expiration Date:

 Vesting Schedule: 

This Option shall be exercisable, in whole or in part, according to the following vesting schedule: 

Twenty-five percent (25%) of the Shares subject to the Option shall vest on the one (1) year anniversary of the Vesting Commencement Date,
and one forty-eighth (1/48th) of the Shares subject to the Option shall vest each month thereafter on the same day of the month as the Vesting Commencement Date (and if there is no corresponding
day, on the last day of the month), subject to Participant continuing to be a Service Provider through each such date. 

 Termination Period: 

This Option shall be exercisable for three (3) months after Participant ceases to be a Service Provider, unless such termination is due to
Participant’s death or Disability, in which case this Option shall be exercisable for twelve (12) months after Participant ceases to be a Service Provider. Notwithstanding the foregoing sentence, in no event may this Option be exercised
after the Term/Expiration Date as provided above and this Option may be subject to earlier termination as provided in Section 13 of the Plan. 
  

	II.	 AGREEMENT 

1. Grant of Option. The Administrator of the Company hereby grants to the Participant named in the Notice of Stock Option Grant in Part
I of this Option Agreement (“Participant”), an option (the “Option”) to purchase the number of Shares set forth in the Notice of Stock Option Grant, at the exercise price per Share set forth in the Notice of Stock Option Grant
(the “Exercise Price”), and subject to the terms and conditions of the Plan, which is incorporated herein by reference. Subject to Section 18 of the Plan, in the event of a conflict between the terms and conditions of the Plan and
this Option Agreement, the terms and conditions of the Plan shall prevail. 
 If designated in the Notice of Stock Option Grant as an
Incentive Stock Option (“ISO”), this Option is intended to qualify as an Incentive Stock Option as defined in Section 422 of the Code. Nevertheless, to the extent that it exceeds the $100,000 rule of Code Section 422(d), this
Option shall be treated as a Nonstatutory Stock Option (“NSO”). Further, if for any reason this Option (or portion thereof) shall not qualify as an ISO, then, to the extent of such nonqualification, such Option (or portion thereof) shall
be regarded as a NSO granted under the Plan. In no event shall the Administrator, the Company or any Parent or Subsidiary or any of their respective employees or directors have any liability to Participant (or any other person) due to the failure of
the Option to qualify for any reason as an ISO. 
 2. Exercise of Option. 

(a) Right to Exercise. This Option shall be exercisable during its term in accordance with the Vesting Schedule set out in the Notice of
Stock Option Grant and with the applicable provisions of the Plan and this Option Agreement. 
 (b) Method of Exercise. This Option
shall be exercisable by delivery of an exercise notice in the form attached as Exhibit A (the “Exercise Notice”) or in a manner and pursuant to such procedures as the Administrator may determine, which shall state
the election to exercise the Option, the number of Shares with respect to which the Option is being exercised (the “Exercised Shares”), and such other representations and agreements as may be required by the Company. The Exercise Notice
shall be accompanied by payment of the aggregate Exercise Price as to all Exercised Shares, together with any applicable tax withholding. This Option shall be deemed to be exercised upon receipt by the Company of such fully executed Exercise Notice
accompanied by the aggregate Exercise Price, together with any applicable tax withholding. 
 No Shares shall be issued pursuant to the
exercise of an Option unless such issuance and such exercise comply with Applicable Laws. Assuming such compliance, for income tax purposes the Shares shall be considered transferred to Participant on the date on which the Option is exercised with
respect to such Shares. 

  
 -2- 

 3. Participant’s Representations. In the event the Shares have not been
registered under the Securities Act of 1933, as amended (the “Securities Act”), at the time this Option is exercised, Participant shall, if required by the Company, concurrently with the exercise of all or any portion of this Option,
deliver to the Company his or her Investment Representation Statement in the form attached hereto as Exhibit B. 

4. Lock-Up Period. Participant hereby agrees that Participant shall not offer, pledge, sell,
contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or otherwise transfer or dispose of, directly or indirectly, any Common Stock (or other
securities) of the Company or enter into any swap, hedging or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of any Common Stock (or other securities) of the Company held by
Participant (other than those included in the registration) for a period specified by the representative of the underwriters of Common Stock (or other securities) of the Company not to exceed one hundred and eighty (180) days following the
effective date of any registration statement of the Company filed under the Securities Act (or such other period as may be requested by the Company or the underwriters to accommodate regulatory restrictions on (i) the publication or other
distribution of research reports and (ii) analyst recommendations and opinions, including, but not limited to, the restrictions contained in NASD Rule 2711(f)(4) or NYSE Rule 472(f)(4), or any successor provisions or amendments
thereto). 
 Participant agrees to execute and deliver such other agreements as may be reasonably requested by the Company or the
underwriter which are consistent with the foregoing or which are necessary to give further effect thereto. In addition, if requested by the Company or the representative of the underwriters of Common Stock (or other securities) of the Company,
Participant shall provide, within ten (10) days of such request, such information as may be required by the Company or such representative in connection with the completion of any public offering of the Company’s securities pursuant to a
registration statement filed under the Securities Act. The obligations described in this Section 4 shall not apply to a registration relating solely to employee benefit plans on Form S-1 or Form S-8 or similar forms that may be promulgated in the future, or a registration relating solely to a Commission Rule 145 transaction on Form S-4 or similar forms that may be
promulgated in the future. The Company may impose stop-transfer instructions with respect to the shares of Common Stock (or other securities) subject to the foregoing restriction until the end of said one hundred and eighty (180) day (or other)
period. Participant agrees that any transferee of the Option or shares acquired pursuant to the Option shall be bound by this Section 4. 

5. Method of Payment. Payment of the aggregate Exercise Price shall be by any of the following, or a combination thereof, at the
election of the Participant: 
 (a) cash; 

(b) check; 

  
 -3- 

 (c) consideration received by the Company under a formal cashless exercise program adopted
by the Company in connection with the Plan; or 
 (d) surrender of other Shares which (i) shall be valued at its Fair Market Value on
the date of exercise, and (ii) must be owned free and clear of any liens, claims, encumbrances or security interests, if accepting such Shares, in the sole discretion of the Administrator, shall not result in any adverse accounting consequences
to the Company. 
 6. Restrictions on Exercise. This Option may not be exercised until such time as the Plan has been approved by the
stockholders of the Company, or if the issuance of such Shares upon such exercise or the method of payment of consideration for such shares would constitute a violation of any Applicable Law. 

7. Non-Transferability of Option. 

(a) This Option may not be transferred in any manner otherwise than by will or by the laws of descent or distribution and may be exercised
during the lifetime of Participant only by Participant. The terms of the Plan and this Option Agreement shall be binding upon the executors, administrators, heirs, successors and assigns of Participant. 

(b) Further, until the Company becomes subject to the reporting requirements of Section 13 or 15(d) of the Exchange Act, or after the
Administrator determines that it is, will, or may no longer be relying upon the exemption from registration of Options under the Exchange Act as set forth in Rule 12h-1(f) promulgated under the Exchange Act
(the “Reliance End Date”), Participant shall not transfer this Option or, prior to exercise, the Shares subject to this Option, in any manner other than (i) to persons who are “family members” (as defined in Rule 701(c)(3)
of the Securities Act) through gifts or domestic relations orders, or (ii) to an executor or guardian of Participant upon the death or disability of Participant. Until the Reliance End Date, the Options and, prior to exercise, the Shares
subject to this Option, may not be pledged, hypothecated or otherwise transferred or disposed of, including by entering into any short position, any “put equivalent position” or any “call equivalent position” (as defined in Rule 16a-1(h) and Rule 16a-1(b) of the Exchange Act, respectively), other than as permitted in clauses (i) and (ii) of this paragraph. 

8. Term of Option. This Option may be exercised only within the term set out in the Notice of Stock Option Grant, and may be exercised
during such term only in accordance with the Plan and the terms of this Option Agreement. 
 9. Tax Obligations. 

(a) Tax Withholding. Participant agrees to make appropriate arrangements with the Company (or the Parent or Subsidiary employing or
retaining Participant) for the satisfaction of all Federal, state, local and foreign income and employment tax withholding requirements applicable to the Option exercise. Participant acknowledges and agrees that the Company may refuse to honor the
exercise and refuse to deliver the Shares if such withholding amounts are not delivered at the time of exercise. 

  
 -4- 

 (b) Notice of Disqualifying Disposition of ISO Shares. If the Option granted to
Participant herein is an ISO, and if Participant sells or otherwise disposes of any of the Shares acquired pursuant to the ISO on or before the later of (i) the date two (2) years after the Date of Grant, or (ii) the date one
(1) year after the date of exercise, Participant shall immediately notify the Company in writing of such disposition. Participant agrees that Participant may be subject to income tax withholding by the Company on the compensation income
recognized by Participant. 
 (c) Code Section 409A. Under Code Section 409A, an Option that vests after
December 31, 2004 (or that vested on or prior to such date but which was materially modified after October 3, 2004) that was granted with a per Share exercise price that is determined by the Internal Revenue Service (the “IRS”)
to be less than the Fair Market Value of a Share on the date of grant (a “discount option”) may be considered “deferred compensation.” An Option that is a “discount option” may result in (i) income recognition by
Participant prior to the exercise of the Option, (ii) an additional twenty percent (20%) federal income tax, and (iii) potential penalty and interest charges. The “discount option” may also result in additional state income,
penalty and interest tax to the Participant. Participant acknowledges that the Company cannot and has not guaranteed that the IRS will agree that the per Share exercise price of this Option equals or exceeds the Fair Market Value of a Share on the
date of grant in a later examination. Participant agrees that if the IRS determines that the Option was granted with a per Share exercise price that was less than the Fair Market Value of a Share on the date of grant, Participant shall be solely
responsible for Participant’s costs related to such a determination. 
 10. Entire Agreement; Governing Law. The Plan is
incorporated herein by reference. The Plan and this Option Agreement constitute the entire agreement of the parties with respect to the subject matter hereof and supersede in their entirety all prior undertakings and agreements of the Company and
Participant with respect to the subject matter hereof, and may not be modified adversely to the Participant’s interest except by means of a writing signed by the Company and Participant. This Option Agreement is governed by the internal
substantive laws but not the choice of law rules of California. 
 11. No Guarantee of Continued Service. PARTICIPANT ACKNOWLEDGES AND
AGREES THAT THE VESTING OF SHARES PURSUANT TO THE VESTING SCHEDULE HEREOF IS EARNED ONLY BY CONTINUING AS A SERVICE PROVIDER AT THE WILL OF THE COMPANY (OR THE PARENT OR SUBSIDIARY EMPLOYING OR RETAINING PARTICIPANT) AND NOT THROUGH THE ACT OF BEING
HIRED, BEING GRANTED THIS OPTION OR ACQUIRING SHARES HEREUNDER. PARTICIPANT FURTHER ACKNOWLEDGES AND AGREES THAT THIS AGREEMENT, THE TRANSACTIONS CONTEMPLATED HEREUNDER AND THE VESTING SCHEDULE SET FORTH HEREIN DO NOT CONSTITUTE AN EXPRESS OR
IMPLIED PROMISE OF CONTINUED ENGAGEMENT AS A SERVICE PROVIDER FOR THE VESTING PERIOD, FOR ANY PERIOD, OR AT ALL, AND SHALL NOT INTERFERE IN ANY WAY WITH PARTICIPANT’S RIGHT OR THE RIGHT OF THE COMPANY (OR THE PARENT OR SUBSIDIARY EMPLOYING OR
RETAINING PARTICIPANT) TO TERMINATE PARTICIPANT’S RELATIONSHIP AS A SERVICE PROVIDER AT ANY TIME, WITH OR WITHOUT CAUSE. 

  
 -5- 

 Participant acknowledges receipt of a copy of the Plan and represents that he or she is
familiar with the terms and provisions thereof, and hereby accepts this Option subject to all of the terms and provisions thereof. Participant has reviewed the Plan and this Option in their entirety, has had an opportunity to obtain the advice of
counsel prior to executing this Option and fully understands all provisions of the Option. Participant hereby agrees to accept as binding, conclusive and final all decisions or interpretations of the Administrator upon any questions arising under
the Plan or this Option. Participant further agrees to notify the Company upon any change in the residence address indicated below. 
  

					
	PARTICIPANT	 		 	HARPOON THERAPEUTICS, INC.
			
	  
	 		 	  

	Signature	 		 	By
			
	  
	 		 	  

	Print Name	 		 	Print Name
			
	  
	 		 	  

		 		 	Title
			
	  
	 		 	
	Residence Address	 		 	

  
 -6- 

 EXHIBIT A 

2015 EQUITY INCENTIVE PLAN 

EXERCISE NOTICE 
 Harpoon Therapeutics,
Inc. 

                          
               

                          
               
 Attention: President 

1. Exercise of Option. Effective as of today,
                        ,         , the undersigned (“Participant”) hereby
elects to exercise Participant’s option (the “Option”) to purchase                     shares of the Common Stock (the
“Shares”) of Harpoon Therapeutics, Inc. (the “Company”) under and pursuant to the 2015 Equity Incentive Plan (the “Plan”) and the Stock Option Agreement dated
                            ,         (the “Option
Agreement”). 
 2. Delivery of Payment. Participant herewith delivers to the Company the full purchase price of the Shares, as
set forth in the Option Agreement, and any and all withholding taxes due in connection with the exercise of the Option. 
 3.
Representations of Participant. Participant acknowledges that Participant has received, read and understood the Plan and the Option Agreement and agrees to abide by and be bound by their terms and conditions. 

4. Rights as Stockholder. Until the issuance of the Shares (as evidenced by the appropriate entry on the books of the Company or of a
duly authorized transfer agent of the Company), no right to vote or receive dividends or any other rights as a stockholder shall exist with respect to the Common Stock subject to an Award, notwithstanding the exercise of the Option. The Shares shall
be issued to Participant as soon as practicable after the Option is exercised in accordance with the Option Agreement. No adjustment shall be made for a dividend or other right for which the record date is prior to the date of issuance except as
provided in Section 13 of the Plan. 
 5. Company’s Right of First Refusal. Before any Shares held by Participant or any
transferee (either being sometimes referred to herein as the “Holder”) may be sold or otherwise transferred (including transfer by gift or operation of law), the Company or its assignee(s) shall have a right of first refusal to purchase
the Shares on the terms and conditions set forth in this Section 5 (the “Right of First Refusal”). 
 (a) Notice of
Proposed Transfer. The Holder of the Shares shall deliver to the Company a written notice (the “Notice”) stating: (i) the Holder’s bona fide intention to sell or otherwise transfer such Shares; (ii) the name of each
proposed purchaser or other transferee (“Proposed Transferee”); (iii) the number of Shares to be transferred to each Proposed Transferee; and (iv) the bona fide cash price or other consideration for which the Holder proposes to
transfer the Shares (the “Offered Price”), and the Holder shall offer the Shares at the Offered Price to the Company or its assignee(s). 

 (b) Exercise of Right of First Refusal. At any time within thirty (30) days
after receipt of the Notice, the Company and/or its assignee(s) may, by giving written notice to the Holder, elect to purchase all, but not less than all, of the Shares proposed to be transferred to any one or more of the Proposed Transferees, at
the purchase price determined in accordance with subsection (c) below. 
 (c) Purchase Price. The purchase price (“Purchase
Price”) for the Shares purchased by the Company or its assignee(s) under this Section 5 shall be the Offered Price. If the Offered Price includes consideration other than cash, the cash equivalent value of the non-cash consideration shall be determined by the Board of Directors of the Company in good faith. 
 (d)
Payment. Payment of the Purchase Price shall be made, at the option of the Company or its assignee(s), in cash (by check), by cancellation of all or a portion of any outstanding indebtedness of the Holder to the Company (or, in the case of
repurchase by an assignee, to the assignee), or by any combination thereof within thirty (30) days after receipt of the Notice or in the manner and at the times set forth in the Notice. 

(e) Holder’s Right to Transfer. If all of the Shares proposed in the Notice to be transferred to a given Proposed Transferee are
not purchased by the Company and/or its assignee(s) as provided in this Section 5, then the Holder may sell or otherwise transfer such Shares to that Proposed Transferee at the Offered Price or at a higher price, provided that such sale
or other transfer is consummated within one hundred and twenty (120) days after the date of the Notice, that any such sale or other transfer is effected in accordance with any applicable securities laws and that the Proposed Transferee agrees
in writing that the provisions of this Section 5 shall continue to apply to the Shares in the hands of such Proposed Transferee. If the Shares described in the Notice are not transferred to the Proposed Transferee within such period, a new
Notice shall be given to the Company, and the Company and/or its assignees shall again be offered the Right of First Refusal before any Shares held by the Holder may be sold or otherwise transferred. 

(f) Exception for Certain Family Transfers. Anything to the contrary contained in this Section 5 notwithstanding, the transfer of
any or all of the Shares during the Participant’s lifetime or on the Participant’s death by will or intestacy to the Participant’s immediate family or a trust for the benefit of the Participant’s immediate family shall be exempt
from the provisions of this Section 5. “Immediate Family” as used herein shall mean spouse, lineal descendant or antecedent, father, mother, brother or sister. In such case, the transferee or other recipient shall receive and hold the
Shares so transferred subject to the provisions of this Section 5, and there shall be no further transfer of such Shares except in accordance with the terms of this Section 5. 

(g) Termination of Right of First Refusal. The Right of First Refusal shall terminate as to any Shares upon the earlier of (i) the
first sale of Common Stock of the Company to the general public, or (ii) a Change in Control in which the successor corporation has equity securities that are publicly traded. 

  
 -2- 

 6. Tax Consultation. Participant understands that Participant may suffer adverse tax
consequences as a result of Participant’s purchase or disposition of the Shares. Participant represents that Participant has consulted with any tax consultants Participant deems advisable in connection with the purchase or disposition of the
Shares and that Participant is not relying on the Company for any tax advice. 
 7. Restrictive Legends and Stop-Transfer Orders. 

(a) Legends. Participant understands and agrees that the Company shall cause the legends set forth below or legends substantially
equivalent thereto, to be placed upon any certificate(s) evidencing ownership of the Shares together with any other legends that may be required by the Company or by state or federal securities laws: 

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 (THE “ACT”) AND MAY NOT BE OFFERED, SOLD
OR OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED UNLESS AND UNTIL REGISTERED UNDER THE ACT OR, IN THE OPINION OF COUNSEL SATISFACTORY TO THE ISSUER OF THESE SECURITIES, SUCH OFFER, SALE OR TRANSFER, PLEDGE OR HYPOTHECATION IS IN COMPLIANCE
THEREWITH. 
 THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO CERTAIN RESTRICTIONS ON TRANSFER AND A RIGHT OF FIRST REFUSAL HELD BY
THE ISSUER OR ITS ASSIGNEE(S) AS SET FORTH IN THE EXERCISE NOTICE BETWEEN THE ISSUER AND THE ORIGINAL HOLDER OF THESE SHARES, A COPY OF WHICH MAY BE OBTAINED AT THE PRINCIPAL OFFICE OF THE ISSUER. SUCH TRANSFER RESTRICTIONS AND RIGHT OF FIRST
REFUSAL ARE BINDING ON TRANSFEREES OF THESE SHARES. 
 THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO RESTRICTIONS ON TRANSFER FOR
A PERIOD OF TIME FOLLOWING THE EFFECTIVE DATE OF THE UNDERWRITTEN PUBLIC OFFERING OF THE COMPANY’S SECURITIES SET FORTH IN AN AGREEMENT BETWEEN THE ISSUER AND THE ORIGINAL HOLDER OF THESE SHARES AND MAY NOT BE SOLD OR OTHERWISE DISPOSED OF BY
THE HOLDER PRIOR TO THE EXPIRATION OF SUCH PERIOD WITHOUT THE CONSENT OF THE COMPANY OR THE MANAGING UNDERWRITER. 
 (b) Stop-Transfer
Notices. Participant agrees that, in order to ensure compliance with the restrictions referred to herein, the Company may issue appropriate “stop transfer” instructions to its transfer agent, if any, and that, if the Company transfers
its own securities, it may make appropriate notations to the same effect in its own records. 

  
 -3- 

 (c) Refusal to Transfer. The Company shall not be required (i) to transfer on
its books any Shares that have been sold or otherwise transferred in violation of any of the provisions of this Exercise Notice or (ii) to treat as owner of such Shares or to accord the right to vote or pay dividends to any purchaser or other
transferee to whom such Shares shall have been so transferred. 
 8. Successors and Assigns. The Company may assign any of its rights
under this Exercise Notice to single or multiple assignees, and this Exercise Notice shall inure to the benefit of the successors and assigns of the Company. Subject to the restrictions on transfer herein set forth, this Exercise Notice shall be
binding upon Participant and his or her heirs, executors, administrators, successors and assigns. 
 9. Interpretation. Any dispute
regarding the interpretation of this Exercise Notice shall be submitted by Participant or by the Company forthwith to the Administrator, which shall review such dispute at its next regular meeting. The resolution of such a dispute by the
Administrator shall be final and binding on all parties. 
 10. Governing Law; Severability. This Exercise Notice is governed by the
internal substantive laws, but not the choice of law rules, of California. In the event that any provision hereof becomes or is declared by a court of competent jurisdiction to be illegal, unenforceable or void, this Exercise Notice shall continue
in full force and effect. 
 11. Entire Agreement. The Plan and Option Agreement are incorporated herein by reference. This Exercise
Notice, the Plan, the Option Agreement and the Investment Representation Statement constitute the entire agreement of the parties with respect to the subject matter hereof and supersede in their entirety all prior undertakings and agreements of the
Company and Participant with respect to the subject matter hereof, and may not be modified adversely to the Participant’s interest except by means of a writing signed by the Company and Participant. 

 

					
	Submitted by:	 		 	Accepted by:
	PARTICIPANT	 		 	HARPOON THERAPEUTICS, INC.
			
	  
	 		 	  

	Signature	 		 	By
			
	  
	 		 	  

	Print Name	 		 	Print Name
			
		 		 	  

		 		 	Title
			
	Address:	 		 	Address:
		 		 	
	  
	 		 	  

 

	  
	 		 	Date Received

  
 -4- 

 EXHIBIT B 

INVESTMENT REPRESENTATION STATEMENT 
  

					
	PARTICIPANT	  	:	  	                                      
          
		  		  	
	COMPANY	  	:	  	HARPOON THERAPEUTICS, INC.
			
	SECURITY	  	:	  	COMMON STOCK
			
	AMOUNT	  	:	  	                                      
           SHARES
		  		  	
	DATE	  	:	  	                                      
           

 In connection with the purchase of the above-listed Securities, the undersigned Participant represents to the
Company the following: 
 (a) Participant is aware of the Company’s business affairs and financial condition and has acquired sufficient
information about the Company to reach an informed and knowledgeable decision to acquire the Securities. Participant is acquiring these Securities for investment for Participant’s 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 of 1933, as amended (the “Securities Act”). 

(b) Participant acknowledges and understands that the Securities constitute “restricted securities” under the Securities Act and have
not been registered under the Securities Act in reliance upon a specific exemption therefrom, which exemption depends upon, among other things, the bona fide nature of Participant’s investment intent as expressed herein. In this connection,
Participant understands that, in the view of the Securities and Exchange Commission, the statutory basis for such exemption may be unavailable if Participant’s representation was predicated solely upon a present intention to hold these
Securities for the minimum capital gains period specified under tax statutes, for a deferred sale, for or until an increase or decrease in the market price of the Securities, or for a period of one (1) year or any other fixed period in the
future. Participant further understands that the Securities must be held indefinitely unless they are subsequently registered under the Securities Act or an exemption from such registration is available. Participant further acknowledges and
understands that the Company is under no obligation to register the Securities. Participant understands that the certificate evidencing the Securities shall be imprinted with any legend required under applicable state securities laws. 

(c) Participant is familiar with the provisions of Rule 701 and Rule 144, each promulgated under the Securities Act, which, in
substance, permit limited public resale of “restricted securities” acquired, directly or indirectly from the issuer thereof, in a non-public offering subject to the satisfaction of certain
conditions. Rule 701 provides that if the issuer qualifies under Rule 701 at the time of the grant of the Option to Participant, the exercise shall be exempt from registration under the Securities Act. In the event the Company becomes
subject to the reporting requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, ninety (90) days thereafter (or such 

 
longer period as any market stand-off agreement may require) the Securities exempt under Rule 701 may be resold, subject to the satisfaction of the
applicable conditions specified by Rule 144, including in the case of affiliates (1) the availability of certain public information about the Company, (2) the amount of Securities being sold during any three (3) month period not
exceeding specified limitations, (3) the resale being made in an unsolicited “broker’s transaction”, transactions directly with a “market maker” or “riskless principal transactions” (as those terms are defined
under the Securities Exchange Act of 1934) and (4) the timely filing of a Form 144, if applicable. 
 In the event that the
Company does not qualify under Rule 701 at the time of grant of the Option, then the Securities may be resold in certain limited circumstances subject to the provisions of Rule 144, which may require (i) the availability of current
public information about the Company; (ii) the resale to occur more than a specified period after the purchase and full payment (within the meaning of Rule 144) for the Securities; and (iii) in the case of the sale of Securities by an
affiliate, the satisfaction of the conditions set forth in sections (2), (3) and (4) of the paragraph immediately above. 
 (d)
Participant further understands that in the event all of the applicable requirements of Rule 701 or 144 are not satisfied, registration under the Securities Act, compliance with Regulation A, or some other registration exemption shall be
required; and that, notwithstanding the fact that Rules 144 and 701 are not exclusive, the Staff of the Securities and Exchange Commission has expressed its opinion that persons proposing to sell private placement securities other than in a
registered offering and otherwise than pursuant to Rules 144 or 701 shall have a substantial burden of proof in establishing that an exemption from registration is available for such offers or sales, and that such persons and their respective
brokers who participate in such transactions do so at their own risk. Participant understands that no assurances can be given that any such other registration exemption shall be available in such event. 

 

			
	PARTICIPANT
	
	  

	Signature
	
	  

	Print Name
	
	  

	Date

  
 -2-EX-10.5

 Exhibit 10.5 
  

 
 December 10, 2016 

VIA EMAIL AND U.S. MAIL 
 Gerald McMahon, PhD 

Dear Jerry, 
 On behalf of Harpoon Therapeutics,
Inc. (“Harpoon” or the “Company”), I am pleased to set forth the terms of your employment with the Company, should you accept our offer letter (the “Agreement”): 

 

	 	1.	 You will be employed on a full-time basis as President and CEO of the Company. You will be responsible for such
duties as are consistent with such position, plus such other duties as may from time to time be assigned to you by the Company. You shall report to the Chairman of the Company’s Board of Directors (the “Board”). Subject to paragraph
12 below, you agree to devote substantially all your business time, best efforts, skill, knowledge, attention and energies to the advancement of the Company’s business and interests and to the performance of your duties and responsibilities as
an employee of the Company. While serving as CEO, you shall serve as a member of the Board. As a Company employee, you will be expected to abide by the Company’s policies that are communicated to employees. Specifically, you will be required to
sign an acknowledgment that you have read and that you understand the Company’s rules of conduct which are included in the Company Handbook. It is contemplated that you will commence full-time employment on or about December 19, 2016, the
exact start date to be mutually agreed upon. Your initial place of work with the Company through September, 1 2017 shall be in Westport, CT, and you shall comply with the requirements of paragraph 2 below while providing services from that location.
While located in Connecticut, you shall be required to travel to the Company’s headquarters in Brisbane, California and to perform other work on the Company’s behalf for up to three weeks per month from January 1, 2017 through
August 30, 2017. On and after September 1, 2017, your place of work shall be at the Company’s headquarters in Brisbane, California. 

  

	 	2.	 You may work from your home office in Westport, CT during your initial period of employment as described in
paragraph 1 above. While providing services from your home office, you shall be required to maintain a proper work environment, in good working order, free of hazards. The Company reserves the right to inspect your home office upon reasonable
advance notice to ensure it is a proper work environment, in good working order, and free of hazards. In addition, in your home office, you are responsible for maintaining the same professional, effective, and efficient communications and workflow
among your supervisors, co-workers, and customers, as you would have were the activities 

  Page
 2
 of 9 
  

	 	
conducted at the Company’s worksite. You may not, however, conduct meetings with customers, clients, or Company employees in your home – any such activities shall be conducted in a
separate business office. You are required to comply with all Company policies while working remotely. In addition, you must keep any confidential or proprietary information of the Company confidential, and you must take necessary precautions to
ensure the protection of proprietary Company and customer information at your home office. If you have any Company files or papers in paper form, they must be kept in a locked filing cabinet when not in your immediate possession. You are not to give
anyone else access to this filing cabinet. The Company will establish policies applicable to telecommuting, communication devices and equipment (computer, laptop, etc.) as it becomes applicable or necessary. If you are injured while working in your
home office, regardless of whether such injury is a minor injury, you must report such injury to the Company so that appropriate workers’ compensation and OSHA paperwork, if applicable, can be completed. All such equipment and information and
data stored on such property remains the property of the Company at all times and may be subject to inspection by the Company. In addition, all such equipment and property of the Company is to be used for business purposes only. The Company will
reimburse you for the cost of supplies (such as paper, pens, highlighters, printer ink, envelopes, and postage) security and communications for you home office, so long as such purchase are approved by the Company in advance. All such reimbursements
will be made in accordance with the Company’s standard expense reimbursement policy. You will not be reimbursed for the cost of any furniture for your home office, nor will you be reimbursed for any costs associated with remodeling your home
office (or your home more generally to contain a home office). 

  

	 	3.	 Your base salary will be at the monthly rate of $34,583.33 (equivalent to an annualized base salary of
$415,000), less all applicable taxes and withholdings, to be paid in installments in accordance with the Company’s regular payroll practices. It is not anticipated that your base salary will increase before the end of the calendar year 2017,
and any increase then or thereafter would be at the Company’s discretion. Your base salary shall be reviewed by the Board annually beginning in 2018 for increase only. 

 

	 	4.	 You will be eligible to earn a target bonus equal to 40% of your annualized base salary while you are employed
by the Company, beginning with the Company’s 2017 fiscal year, based on your individual performance and the Company’s performance during the applicable fiscal year, as determined in good faith by the Board. The performance milestones shall
be mutually agreed upon between you and the Board each year, and shall be reasonably consistent with the Company’s approved business plan for the fiscal year. Except as provided in paragraph 7 and 8 below, you must be an active employee of the
Company on the date any bonus is distributed in order to be eligible for and to earn a bonus award, as it also serves as an incentive to remain employed by the Company. 

 

	 	5.	 In order to assist with relocating to the San Francisco area, the Company will provide with relocation subsidy
assistance in the form of cash payments such that you will retain, on an after-tax basis, an amount equal to $70,000. The relocation subsidy assistance will be paid to you in four equal installments on a
quarterly basis commencing on or about January 1, 2017. You may use relocation subsidy assistance payments for any purpose. In addition to the relocation subsidy assistance, you shall be entitled to reimbursement of up to $60,000

  Page
 3
 of 9 
  

	 	
on a non-taxable basis for amounts that would otherwise qualify as being tax deductible by an employee under federal tax laws in connection with your move
to San Francisco, including but not limited to (i) paying rent for temporary housing the San Francisco area and flying to and from California and Connecticut during your initial period of employment while in Westport, Connecticut and
(ii) shipping of household goods and personal vehicles to California. Any reimbursement under this paragraph shall be paid within 30 days after you submit proper receipts to the Company substantiating eligibility for reimbursement. Should you
resign without Good Reason (as defined below) prior to the first anniversary of your start date you must reimburse the Company 50% of both the relocation subsidy assistance payments and reimbursements for moving related expenses paid to you under
this paragraph 5. 

  

	 	6.	 Subject to the terms and conditions thereof and all eligibility requirements, you may participate in any and
all benefit programs that the Company establishes and makes available to its employees from time to time. You will also be eligible for up to four weeks of vacation per calendar year in accordance with the Company’s vacation policy. The benefit
programs made available by the Company, and the rules, terms, and conditions for participation in such benefit programs, may be changed by the Company at any time without advance notice. In any case, the Company will reimburse you for out of pocket
expenses you incur to pay for the Company approved healthcare coverage for you or members of your family in accordance with all applicable law. The Company shall maintain and pay all premiums on a whole life insurance policy with an annual coverage
amount as mutually agreed between the Company and you. In addition, the Company shall maintain and pay all premiums related to supplemental life insurance policy with an annual premium amount as mutually agreed between the Company and you. Any
imputed income related to the payment of life insurance will be displayed on your paystub. 

  

	 	7.	 If within 90 days prior to or within 12 months following a Change in Control (as defined on Appendix A hereto),
your employment is terminated by the Company without Cause (as defined on Appendix A hereto) or you terminate your employment for Good Reason (as defined on Appendix A hereto), and provided you enter into (and do not revoke) an agreement releasing
all claims you may have against the Company (the form of such agreement to be provided by the Company) 

  

	 	a.	 all of your then outstanding unvested equity awards (such as unexercised options or restricted stock) will
immediately vest in full at the maximum level provided under the award agreement; 

  

	 	b.	 the Company will pay you as severance an aggregate amount equivalent to 12 months of your then-current base
salary, less all applicable taxes and withholdings, which severance pay will be paid ratably in bi-weekly installments in accordance with the Company’s normal payroll practices, but in no event shall any
payments be paid or provided until the release of claims actually becomes effective and irrevocable; 

  Page
 4
 of 9 
  

	 	c.	 the Company shall pay to you an amount equal to the product of (i) the target bonus, and (ii) the
ratio of (x) the number of days elapsed from the beginning of the fiscal year during which such termination of employment occurs until the date of such termination, to (y) 365, payable as of the same time as annual bonuses are paid to other
senior executives; and 

  

	 	d.	 should you timely elect and be eligible to continue receiving group medical coverage pursuant to the
“COBRA” law, and so long as the Company can provide such benefit without violating the nondiscrimination requirements of applicable law, the Company will, for a period of 12 months following termination of your employment, reimburse you
for payments you make for COBRA coverage, except that in no event will such payments exceed the amount the Company then pays for health insurance coverage for active employees. The remaining balance of any premium costs shall timely be paid by you
on a monthly basis for as long as, and to the extent that, you remain eligible for COBRA continuation. Notwithstanding the foregoing, if the Company determines in its sole discretion that it cannot provide the foregoing benefit without potentially
violating, or being subject to an excise tax under, applicable law (including, without limitation, Section 2716 of the Public Health Service Act), the Company will in lieu thereof provide you a taxable monthly payment in an amount such that,
after withholding at the maximum applicable federal and state income and employment tax withholding rate, receive an amount equal to the monthly COBRA premium that you would be required to pay to continue your group health coverage in effect on the
termination of employment date (which amount will be based on the premium for the first month of COBRA coverage), which payments will be made regardless of whether you elect COBRA continuation coverage and will commence on the month following your
termination of employment and will end on the earlier of (x) the date upon which you obtain other employment or (y) the date the Company has paid an amount equal to twelve (12) months. For the avoidance of doubt, the taxable payments
in lieu of COBRA reimbursements may be used for any purpose, including, but not limited to continuation coverage under COBRA, and will be subject to all applicable tax withholdings. 

 

	 	8.	 If, at any time (other than as provided in paragraph 7 above) in connection with a Change in Control), your
employment is terminated by the Company without Cause or if you terminate your employment for Good Reason, and provided you enter into and do not revoke a release of claims in a form provided by the Company: 

 

	 	a.	 the Company will pay you as severance pay an aggregate amount equivalent to twelve (12) months of your
then-current base salary, less all applicable taxes and withholdings, which severance pay will be paid ratably in bi-weekly installments in accordance with the Company’s normal payroll practices, but in
no event shall any payments be paid or provided until the release of claims actually becomes effective and irrevocable; 

  

	 	b.	 the Company shall pay to you an amount equal to the product of (i) the amount of the conus that would have
been payable to you under paragraph 4 if you were still employed through the regular payment based on the Company’s achievement against the performance goals applicable to such year (after deeming any individual

  Page
 5
 of 9 
  

	 	
goals to be met at the target level), and (B) the ratio of (x) the number of days elapsed during the fiscal year during which such termination of employment occurs on or prior to the
date of such termination to (y) 365, payable as of the same time as annual bonuses are paid to other senior executives; 

  

	 	c.	 should you timely elect and be eligible to continue receiving group medical coverage pursuant to the
“COBRA” law, and so long as the Company can provide such benefit without violating the nondiscrimination requirements of applicable law, the Company will, for a period of nine months following your termination of employment, reimburse you
for payments you make for COBRA coverage, except that in no event will such payments exceed the amount the Company then pays for health insurance coverage for active employees. The remaining balance of any premium costs shall timely be paid by you
on a monthly basis for as long as, and to the extent that, you remain eligible for COBRA continuation. 

 You will not
continue to vest in any equity after termination of employment. 
  

	 	9.	 Notwithstanding anything to the contrary in this letter, no payments of “deferred compensation” (the
“Deferred Payments”) within the meaning of Section 409A of the Internal Revenue Code of 1986, as amended (the “Code”) and the final regulations and official guidance thereunder (“Section 409A”) will be payable
until you have a “separation from service” within the meaning of Section 409A. Similarly, no severance payable to you, if any, pursuant to this letter that otherwise would be exempt from Section 409A pursuant to Treasury
Regulation Section 1.409A-1(b)(9) will be payable until you have a “separation from service” within the meaning of Section 409A. If and to the extent necessary to avoid subjecting Employee
to an additional tax under Section 409A, payment of the Deferred Payments, if any, that otherwise would be payable to you within the first six months following your termination of employment will instead be delayed until the date that is six
months and one-day following your termination of employment (except where your termination of employment is due to your death). All subsequent Deferred Payments, if any, will be payable in accordance with the
payment schedule applicable to each payment or benefit. Any severance payment that satisfies the requirements of the “short-term deferral” rule set forth in Section 1.409A-1(b)(4) of the
Treasury Regulations shall not constitute Deferred Payments for purposes herein. Any amount paid under this letter that qualifies as a payment made as a result of an involuntary separation from service pursuant to
Section 1.409A-1(b)(9)(iii) of the Treasury Regulations that does not exceed the Section 409A Limit (as defined below) will not constitute Deferred Payments for purposes herein. For purposes of this
letter, “Section 409A Limit” means two (2) times the lesser of: (x) your annualized compensation based upon the annual rate of pay paid to you during your taxable year preceding your taxable year of your termination of
employment as determined under, and with such adjustments as are set forth in, Treasury Regulation 1.409A-1(b)(9)(iii)(A)(1) and any Internal Revenue Service guidance issued with respect thereto, or
(y) the maximum amount that may be taken into account under a qualified plan pursuant to Section 401(a)(17) of the Code for the year in which your employment is terminated. Each payment and benefit payable under this offer letter is
intended to constitute a separate payment for purposes of the Section 409A-related regulations. All subsequent Deferred Compensation Separation Benefits, if any, will be 

  Page
 6
 of 9 
  

	 	
payable in accordance with the payment schedule applicable to each payment or benefit. To the extent that the health care continuation reimbursement under this Agreement, or any other
reimbursement or in-kind benefit plan or arrangement in which you participate, including but not limited to reimbursements under paragraph 5 of this Agreement, provide for a “deferral of
compensation” within the meaning of Section 409A and does not otherwise comply with Section 409A, (i) the amount eligible for reimbursement or in-kind benefit in one calendar year may not
affect the amount eligible for reimbursement or in-kind benefit in any other calendar year, (ii) the right to the applicable reimbursement or benefit is not subject to liquidation or exchange for another
benefit or payment, (iii) to the extent there is any reimbursement of an expense, such reimbursement must be made on or before the last day of the calendar year following the calendar year in which the expense was incurred, and (iv) except
as specifically provided herein or in the applicable reimbursement arrangement, in-kind benefits will only be provided, and reimbursements will only be made for expenses incurred, during your lifetime. The
foregoing provisions are intended to comply with or be exempt from the requirements of Section 409A so that none of the severance payments and benefits to be provided hereunder will be subject to the additional tax imposed under
Section 409A, and any ambiguities or ambiguous terms herein will be interpreted to so comply or be exempt. In no event will the Company reimburse you for any taxes that may be imposed on you as a result of Section 409A. You and the Company
agree to work together in good faith to consider amendments to this Agreement and to take such reasonable actions which are necessary, appropriate or desirable to avoid imposition of any additional tax or income recognition prior to actual payment
to you under Section 409A. 

  

	 	10.	 The Company will grant to you a stock option grant (the “Option”) under the Company’s equity
incentive plan (the “Stock Plan”) on your start date to purchase of 1,600,000 shares of common stock of the Company representing 3.0% of the Company’s fully diluted capitalization (assuming the completion of a $30 million Series
B preferred stock financing and the dilution associated with that financing). This Option grant shall have a price per share exercise price equal to the fair market value of an underlying share of Company common as determined by the Board on the
date of grant. The fair market value of a share of the Company’s common stock is $0.12 as determined under the Company’s most recent Section 409A valuation. You may be eligible for future option grants. Please note, any additional
option grant(s) will be subject to requisite Board approval and shall have a price per share exercise price equal to the fair market value at the time of Board approval. In particular, should a spinout housing all or part of the Maverick technology
be created and should that company be led by a different team, you will be issued a stock option for an additional 800,000 shares to bring your total potential ownership (calculated on a fully diluted basis assuming the $30M financing) to 4.5%. The
Option will be evidenced in writing by, and subject to the terms of, the Stock Plan and a stock option agreement substantially in the form attached to this Agreement. The Option will vest 25% after one year, with monthly vesting over the following
three (3) years so that it vests 100% over four (4) years after the date of grant. Notwithstanding the foregoing, the Option shall vest 100% upon a Change in Control. The Option shall be granted in the form of an incentive stock option, to
the maximum extent permitted under the Code. The shares acquired upon exercise of the Option shall be subject to tag along rights in the event that shares are sold by other stock holders in connection with a Change in Control. The Company shall not

  Page
 7
 of 9 
  

	 	
have the right to call shares you acquire under the Option prior to a Change in Control. The additional stock option for the Maverick spinout described above shall be made on the same terms and
conditions as the Option except that your vesting commencement date shall be your start date. You may be eligible to receive such future stock option grants as the Board shall deem appropriate. 

 

	 	11.	 As a condition of your employment, you agree to execute an At-Will
Employment, Confidential Information, Invention Assignment and Arbitration Agreement (the “Employment Agreement”), a copy of which is attached as Appendix B hereto. The Employment Agreement requires, among other provisions, the assignment
of patent rights to any invention made during your employment at the Company, and non-disclosure of Company proprietary information. In the event of any dispute or claim relating to or arising out of our
employment relationship, you and the Company agree that: (i) any and all disputes between you and the Company shall be fully and finally resolved by binding arbitration; (ii) you are waiving any and all rights to a jury trial but all court
remedies will be available in arbitration; (iii) all disputes shall be resolved by a neutral arbitrator who shall issue a written opinion; (iv) the arbitration shall provide for adequate discovery; and (v) the Company shall pay all
the arbitration fees, except an amount equal to the filing fees you would have paid had you filed a complaint in a court of law. 

  

	 	12.	 We ask that, if you have not already done so, you disclose to the Company any and all agreements relating to
your prior employment that may affect your eligibility to be employed by the Company or limit the manner in which you may be employed. It is the Company’s understanding that any such agreements will not prevent you from performing the duties of
your position, and you represent that such is the case. Moreover, you agree that, during the term of your employment with the Company, you will not engage in any other employment, occupation, consulting or other business activity directly related to
the business in which the Company is now involved or becomes involved during the term of your employment, nor will you engage in any other activities that conflict with your obligations to the Company. 

Notwithstanding the foregoing anything to the contrary in this Agreement, you may serve on the board of directors of up to two private or
public companies, so long such service does not conflict with the interests of the Company. Currently, it is understood that you are serving on the Board of CLDX. You will also be permitted to engage with one additional company as a member of a
Scientific Advisory Board so long as such engagement does not conflict with the interests of the Company. You will be permitted to retain your appointment as an Adjunct Professor at Yale University. Also, you agree not to bring any third party
confidential information to the Company, including that of your former employer, and that in performing your duties for the Company you will not in any way utilize any such information. 

 

	 	13.	 You agree to provide to the Company, within three days of your hire date, documentation of your eligibility to
work in the United States, as required by the Immigration Reform and Control Act of 1986. If you do not do this, our employment relationship with you may be terminated. 

  Page
 8
 of 9 
  

	 	14.	 The Company may undertake a background investigation and reference check in accordance with applicable law and
has provided or will provide you with the requisite background check forms via separate cover. This investigation and reference check may include a consumer report, as defined by the Fair Credit Reporting Act (“FCRA”), 15 U.S.C. 1681a,
and/or an investigative consumer report, as defined by FCRA, 15 U.S.C. 1681a, and California Civil Code 1786.2(c). This investigation may include information bearing on your credit worthiness. If it does, the Company will provide you with additional
information on such a credit check via separate cover. This job offer is contingent upon a clearance of such a background investigation and/or reference check and upon your written authorization to obtain a consumer report and/or investigative
consumer report. 

  

	 	15.	 The Company is excited about your joining and looks forward to a beneficial and productive relationship.
Nevertheless, you should be aware that your employment with the Company is for no specified period and constitutes at-will employment. As a result, you are free to resign at any time, for any reason or for no
reason. Similarly, the Company is free to conclude its employment relationship with you at any time, with or without cause, and with or without notice. We request that, in the event of resignation, you give the Company at least two weeks’
notice. Nothing in this letter shall be construed as an agreement, either express or implied, to pay you any compensation or grant you any benefit beyond the end of your employment with the Company, except to the extent specifically set forth in
Sections 7 and 8 hereof. 

 If you agree with the employment provisions of this letter, please sign the enclosed duplicate
of this letter in the space provided below and return it to me, along with a signed copy of the Employment Agreement. If you do not accept this offer by December 10, 2016, this offer will be revoked. This letter, along with any agreements
relating to proprietary rights between you and the Company, sets forth the terms of your employment with the Company and supersedes any prior representations or agreements including, but not limited to, any representations made during your
recruitment, interviews or pre-employment negotiations, whether written or oral. This letter, including, but not limited to, its at-will employment provision, may not be
modified or amended except by a written agreement signed by a duly-authorized representative of the Board and you. 
  

	
	Very Truly Yours,
	
	/s/ Luke Evnin
	
	Name: Luke Evnin
	Title: Member of the Board

  Page
 9
 of 9 
  

 Acknowledgement 

The foregoing correctly sets forth the terms of my at-will employment by Harpoon Inc. I am not relying on any
representations other than those set forth above. 
  

									
					
	By:	 	/s/ Gerald McMahon, PhD	 		 		 	Date: 12/10/16
	Name:	 	Gerald McMahon, PhD	 		 		 	

 APPENDIX A 

The following terms are used in paragraphs 7 and 8 of the offer letter to which this appendix is appended; “Executive” refers to Gerald McMahon.

 1) “Cause” means any of: 
 (a) Executive’s
conviction of, or plea of guilty or nolo contendere to, any crime involving dishonesty or moral turpitude; or b) a good faith finding by the Company that the Executive has (i) engaged in dishonesty, willful misconduct or gross negligence with
respect to his employment duties, (ii) materially breached or threatened to breach the terms of any confidentiality agreement or any similar agreement with the Company or any prior employers, (iii) materially violated Company policies or
procedures, and/or (iv) failed to perform his assigned duties to the Company’s satisfaction following notice of such failure by the Company and a period of 15 days to cure and failure to cure such violation. 

2) “Good Reason” means the occurrence, without the Executive’s prior written consent, of any of the following events: 

(i) a material reduction in the Executive’s authority, duties, or responsibilities; (ii) the relocation of the principal place at which the Executive
provides services to the Company (which is currently Brisbane, California) by at least 50 miles and to a location such that Executive’s daily commuting distance is increased; (iii) a material reduction of the Executive’s base salary
(other than in connection with, and in an amount substantially proportionate to, reductions made by the Company to the base salaries and/or target bonuses of other similarly-situated employees); or (iv) a material breach by the Company of any
of its other material obligations under the Agreement, including but not limited to failure of the Company to make any material payment or provide any material benefit under the Agreement, such as grant of the Option. 

No resignation will be treated as a resignation for Good Reason unless (x) the Executive has given written notice to the Company of his intention to
terminate his employment for Good Reason, describing the grounds for such action, no later than 90 days after the first occurrence of such circumstances, (y) the Executive has provided the Company with at least 30 days in which to cure the
circumstances, and (z) if the Company is not successful in curing the circumstances, the Executive ends his employment within 30 days following the cure period in (y). 

3) “Change in Control” means any of the following: 

(i) the acquisition by an individual, entity or group (within the meaning of Section 13(d)(3) or 14(d)(2) of the Securities Exchange Act of 1934 (the
“Exchange Act”) (a “Person”) of beneficial ownership of any capital stock of the Company if, after such acquisition, such Person beneficially owns (within the meaning of Rule 13d-3 under
the Exchange Act) more than 50% of either (x) the 

 
then-outstanding shares of common stock of the Company (the “Outstanding Company Common Stock”) or (y) the combined voting power of the
then-outstanding securities of the Company entitled to vote generally in the election of directors (the “Outstanding Company Voting Securities”); provided, however, that for purposes of this
subsection any acquisition directly from the Company will not be a Change in Control, nor will any acquisition by any individual, entity, or group pursuant to a Business Combination (as defined below) that complies with clause (ii) of this
definition; 
 (ii) the consummation of a merger, consolidation, reorganization, recapitalization or share exchange involving the Company or a sale or other
disposition of all or substantially all (i.e., in excess of 65% or in excess of 50% but less than 65% at the discretion of the Board of Directors of the Company) of the assets of the Company (a “Business Combination”), unless, immediately
following such Business Combination, all or substantially all of the individuals and entities who were the beneficial owners of the Outstanding Company Common Stock and Outstanding Company Voting Securities immediately prior to such Business
Combination beneficially own, directly or indirectly, more than 50% of the then-outstanding shares of common stock and the combined voting power of the then-outstanding securities entitled to vote generally in the election of directors,
respectively, of the resulting or acquiring corporation in such Business Combination (which shall include a corporation that as a result of such transaction owns the Company or substantially all of the Company’s assets either directly or
through one or more subsidiaries) in substantially the same proportions as their ownership of the Outstanding Company Common Stock and Outstanding Company Voting Securities, respectively, immediately prior to such Business Combination; or 

(iii) the liquidation or dissolution of the Company; provided that, where required to avoid additional taxation under Section 409A, the event that occurs
must also be a “change in the ownership or effective control of a corporation, or a change in the ownership of a substantial portion of the assets of a corporation” as defined in Treasury Reg. §
l.409A-3(i)(5). 

  
 -2-

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00290-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00290-of-00352.parquet"}]]