Document:

EX-4.1

 Exhibit 4.1 

ALPINE IMMUNE SCIENCES, INC. 

AMENDED AND RESTATED 2015 STOCK PLAN 

As Amended through June 9, 2016 (the “Effective Date”) 

BACKGROUND 
 A. Alpine
Immune Sciences, Inc., a Delaware corporation (the “Company”), with the approval of its board of directors and stockholders, previously adopted the Alpine Immune Sciences, Inc. 2015 Stock Plan, as amended by that certain Amendment
No. 1 to the Alpine Immune Sciences, Inc. 2015 Stock Plan (together, the “Old Plan”). 
 B. Effective as of the
Effective Date, with the approval of its board of directors and stockholders, the Company now wishes to amend and restate the Old Plan to, among other things: (i) remove the default Double-Trigger Acceleration provision described in
Section 14 of the Old Plan, and (ii) increase the number of shares of Common Stock reserved for issuance under the Old Plan from 1,250,000 to 2,394,935, all by amending and restating the Old Plan in its entirety, upon the terms set forth
in this Amended and Restated Alpine Immune Sciences, Inc. 2015 Stock Plan (this “Plan”). 
 C. It is the intention that all
Shares (including related Options or Stock Purchase Rights, each as defined in the Old Plan) that were issued or sold in accordance with the Old Plan prior to the Effective Date shall continue to be governed by the Old Plan and that all Shares
(including related Options or Stock Purchase Rights, each as defined in this Plan) issued or sold on or after the Effective Date will now be governed by this Plan. 

PLAN 
 1. Purposes
of the Plan. The purposes of this Alpine Immune Sciences, Inc. Amended and Restated 2015 Stock Plan (this “Plan”) are to attract and retain the best available personnel for positions of substantial responsibility, to
provide additional incentive to Employees and Consultants, and to promote the success of the Company’s business. Options granted under the Plan may be Incentive Stock Options or Nonstatutory Stock Options, as determined by the Administrator at
the time of grant of an Option and subject to the applicable provisions of Section 422 of the Code and the regulations promulgated thereunder. Stock purchase rights may also be granted under the Plan. The Company intends that the Plan comply
with Section 409A of the Code (including any amendments or replacements of such section), and the Plan shall be so construed. 
 2.
Definitions. As used herein, the following definitions shall apply: 
 (a)
“Administrator” means the Board or its Committee appointed pursuant to Section 4 of the Plan. 

(b) “Affiliate” means an entity other than a Subsidiary (as defined below) which, together with the
Company, is under common control of a third person or entity. 
 (c) “Applicable Laws” means the legal
requirements relating to the administration of stock option and restricted stock purchase plans under applicable U.S. state corporate laws, U.S. federal and applicable state securities laws, the Code, any Stock Exchange rules or regulations, and the
applicable laws of any other country or jurisdiction where Options or Stock Purchase Rights are granted under the Plan, as such laws, rules, regulations, and requirements shall be in place from time to time. 

 (d) “Board” means the board of directors of the Company.

 (e) “Cause” for termination of a Participant’s Continuous Service Status will exist if the
Participant is terminated for any of the following reasons: (i) Participant’s willful failure substantially to perform his or her duties and responsibilities to the Company or deliberate violation of a Company policy;
(ii) Participant’s commission of any act of fraud, embezzlement, dishonesty, or any other willful misconduct that has caused or is reasonably expected to result in material injury to the Company; (iii) unauthorized use or disclosure
by Participant of any proprietary information or trade secrets of the Company or any other party to whom the Participant owes an obligation of nondisclosure as a result of his or her relationship with the Company; or (iv) Participant’s
willful breach of any of his or her obligations under any written agreement or covenant with the Company. The determination as to whether a Participant is being terminated for Cause shall be made in good faith by the Company and shall be final and
binding on the Participant. The foregoing definition does not in any way limit the Company’s ability to terminate a Participant’s employment or consulting relationship at any time as provided in Section 5(d) below, and the term
“Company” will be interpreted to include any Subsidiary, Parent, Affiliate, or successor thereto, if appropriate.  

(f) “Change of Control” means a sale of all or substantially all of the Company’s assets, or any
stock sale, merger, or consolidation of the Company with or into another corporation or business entity other than a stock sale, merger, or consolidation in which the holders of more than fifty percent (50%) of the shares of capital stock of the
Company outstanding immediately prior to such transaction continue to hold (either by the voting securities remaining outstanding or by their being converted into voting securities of the surviving entity) more than fifty percent (50%) of the total
voting power represented by the voting securities of the Company, or such surviving entity, outstanding immediately after such transaction; provided, however, that a bona fide equity financing by the Company will not be deemed to be a Change
of Control. 
 (g) “Code” means the Internal Revenue Code of 1986, as amended from time to time. 

(h) “Committee” means one or more committees or subcommittees of the Board appointed by the Board to
administer the Plan in accordance with Section 4 below. 
 (i) “Common Stock” means the Common
Stock of the Company. 
 (j) “Company” means Alpine Immune Sciences, Inc., a Delaware corporation.

 (k) “Consultant” means any person, including an advisor, who is engaged by the Company or any
Parent, Subsidiary, or Affiliate to render services and is compensated for such services, and any Director of the Company whether compensated for such services or not. 

(l) “Continuous Service Status” means the absence of any interruption or termination of service as an
Employee or Consultant. Continuous Service Status as an Employee or Consultant shall not be considered interrupted in the case of: (i) sick leave; (ii) military leave; (iii) any other leave of absence approved by the Administrator;
provided, however, that such leave is for a period of not more than ninety (90) days, unless reemployment upon the expiration of such leave is guaranteed by contract or statute, or unless provided otherwise pursuant to Company policy
adopted from time to time; or (iv) in the case of transfers between locations of the Company or between the Company, its Parents, Subsidiaries, Affiliates, or their respective successors. A change in status from an Employee to a Consultant or
from a Consultant to an Employee will not constitute an interruption of Continuous Service Status. 

 (m) “Corporate Transaction” means a sale of all or
substantially all of the Company’s assets, or a merger, consolidation, or other capital reorganization of the Company with or into another corporation or business entity and includes a Change of Control. 

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

(o) “Employee” means any person employed by the Company or any Parent, Subsidiary, or Affiliate, with
the status of employment determined based upon such factors as are deemed appropriate by the Administrator in its discretion, subject to any requirements of the Code or the Applicable Laws. The payment by the Company of a director’s fee to a
Director shall not be sufficient to constitute “employment” of such Director by the Company. 
 (p)
“Exchange Act” means the Securities Exchange Act of 1934, as amended from time to time. 
 (q)
“Fair Market Value” means, as of any date, the fair market value of the Common Stock, as determined by the Administrator in good faith on such basis as it deems appropriate and applied consistently with respect
to Participants, and subject to compliance with Section 409A of the Code. Whenever possible, the determination of Fair Market Value shall be based upon the closing price for the Shares as reported in The Wall Street Journal for the
applicable date. 
 (r) “Incentive Stock Option” means an Option intended to qualify as an incentive
stock option within the meaning of Section 422 of the Code, as designated in the applicable Option Agreement. 
 (s)
“Involuntary Termination” means termination of a Participant’s Continuous Service Status under the following circumstances: (i) termination without Cause by the Company or a Subsidiary, Parent,
Affiliate or successor thereto, as appropriate; or (ii) voluntary termination by the Participant within thirty (30) days following (A) a material reduction in the Participant’s job responsibilities, provided that neither a mere
change in title alone nor reassignment following a Change of Control to a position that is substantially similar to the position held prior to the Change of Control shall constitute a material reduction in job responsibilities; (B) relocation
by the Company or a Subsidiary, Parent, Affiliate, or successor thereto, as appropriate, of the Participant’s work site to a facility or location more than thirty (30) miles from the Participant’s principal work site for the Company
at the time of the Change of Control; or (C) a reduction in Participant’s then-current base salary by at least five percent (5%); provided, however, that an
across-the-board reduction in the salary level of all other employees or consultants in positions similar to the Participant’s by the same percentage amount as part
of a general salary level reduction shall not constitute such a salary reduction. 
 (t) “Listed Security” means any
security of the Company that is listed or approved for listing on a national securities exchange or designated or approved for designation as a national market system security on an interdealer quotation system by the National Association of
Securities Dealers, Inc. 
 (u) “Named Executive” means any individual who, on the last day of the
Company’s fiscal year, is the chief executive officer of the Company (or is acting in such capacity) or among the four most highly compensated officers of the Company (other than the chief executive officer). Such officer status shall be
determined pursuant to the executive compensation disclosure rules under the Exchange Act. 

 (v) “Nonstatutory Stock Option” means an Option not
intended to qualify as an Incentive Stock Option, as designated in the applicable Option Agreement. 
 (w)
“Option” means a stock option granted pursuant to the Plan. 
 (x) “Option
Agreement” means a written document, the form(s) of which shall be approved from time to time by the Administrator, reflecting the terms of an Option granted under the Plan and includes any documents attached to or incorporated
into such Option Agreement, including, but not limited to, a notice of stock option grant and a form of exercise notice. 
 (y)
“Option Exchange Program” means a program approved by the Administrator whereby outstanding Options are exchanged for Options with a lower exercise price or are amended to decrease the exercise price as a result
of a decline in the Fair Market Value of the Common Stock. 
 (z) “Optioned Stock” means the Common
Stock subject to an Option. 
 (aa) “Optionee” means an Employee or Consultant who receives an Option.

 (bb) “Parent” means a “parent corporation,” whether now or hereafter existing, as defined
in Section 424(e) of the Code, or any successor provision. 
 (cc) “Participant” means any holder
of one or more Options or Stock Purchase Rights, or the Shares issuable or issued upon exercise of such awards, under the Plan. 
 (dd)
“Plan” means this Alpine Immune Sciences, Inc. Amended and Restated 2015 Stock Plan. 
 (ee)
“Reporting Person” means an officer, Director, or greater than ten percent (10%) stockholder of the Company within the meaning of Rule 16a-2 under the Exchange Act, who is
required to file reports pursuant to Rule 16a-3 under the Exchange Act. 
 (ff)
“Restricted Stock” means Shares of Common Stock acquired pursuant to a grant of a Stock Purchase Right under Section 10 below. 

(gg) “Restricted Stock Purchase Agreement” means a written document, the form(s) of which shall be
approved from time to time by the Administrator, reflecting the terms of a Stock Purchase Right granted under the Plan and includes any documents attached to such agreement. 

(hh) “Rule 16b-3” means Rule
16b-3 promulgated under the Exchange Act, as amended from time to time, or any successor provision. 

(ii) “Share” means a share of the Common Stock, as adjusted in accordance with Section 13 of the
Plan. 
 (jj) “Stock Exchange” means any stock exchange or consolidated stock price reporting system
on which prices for the Common Stock are quoted at any given time. 
 (kk) “Stock Purchase Right”
means the right to purchase Common Stock pursuant to Section 10 below. 

 (ll) “Subsidiary” means a “subsidiary
corporation,” whether now or hereafter existing, as defined in Section 424(f) of the Code, or any successor provision. 
 (mm)
“Ten Percent Holder” means a person 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. 

3. Stock Subject to the Plan. Subject to the provisions of Section 13 of the Plan, the maximum aggregate number of
Shares that may be sold under the Plan is two million three hundred ninety-four thousand nine hundred thirty-five (2,394,935) Shares of Common Stock. The Shares may be authorized, but unissued, or reacquired Common Stock. If an award should expire
or become unexercisable for any reason without having been exercised in full, or is surrendered pursuant to an Option Exchange Program, the unpurchased Shares that were subject thereto shall, unless the Plan shall have been terminated, become
available for future grant under the Plan. In addition, any Shares of Common Stock which are retained by the Company upon exercise of an award in order to satisfy the exercise or purchase price for such award or any withholding taxes due with
respect to such exercise or purchase shall be treated as not issued and shall continue to be available under the Plan. Shares issued under the Plan and later repurchased by the Company pursuant to any repurchase right which the Company may have
shall not be available for future grant under the Plan. 
 4. Administration of the Plan. 

(a) General. The Plan shall be administered by the Board or a Committee, or a combination thereof, as determined by the
Board. The Plan may be administered by different administrative bodies with respect to different classes of Participants and, if permitted by the Applicable Laws, the Board may authorize one or more officers to make awards under the Plan. 

(b) Committee Composition. If a Committee has been appointed pursuant to this Section 4, such Committee shall
continue to serve in its designated capacity until otherwise directed by the Board. From time to time the Board may increase the size of any Committee and appoint additional members thereof, remove members (with or without cause) and appoint new
members in substitution therefor, fill vacancies (however caused) and remove all members of a Committee and thereafter directly administer the Plan, all to the extent permitted by the Applicable Laws and, in the case of a Committee administering the
Plan in accordance with the requirements of Rule 16b-3 or Section 162(m) of the Code, to the extent permitted or required by such provisions. 

(c) Powers of the Administrator. Subject to the provisions of the Plan and in the case of a Committee, the specific
duties delegated by the Board to such Committee, the Administrator shall have the authority, in its discretion: 
 (i) to determine the
Fair Market Value of the Common Stock, in accordance with Section 2(q) of the Plan; provided, however, that such determination shall be applied consistently with respect to Participants under the Plan; 

(ii) to select the Employees and Consultants to whom Options and Stock Purchase Rights may from time to time be granted; 

(iii) to determine whether and to what extent Options and Stock Purchase Rights are granted; 

(iv) to determine the number of Shares of Common Stock to be covered by each award granted; 

 (v) to approve the form(s) of agreement(s) used under the Plan; 

(vi) to determine the terms and conditions, not inconsistent with the terms of the Plan, of any award granted hereunder, which terms and
conditions include but are not limited to the exercise or purchase 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 Option, Optioned Stock, Stock Purchase Right, or Restricted Stock, based in each case on such factors as the Administrator, in its sole discretion, shall determine; 

(vii) to determine whether and under what circumstances an Option may be settled in cash under Section 9 (c) instead of Common Stock;

 (viii) to implement an Option Exchange Program on such terms and conditions as the Administrator in its discretion deems appropriate;
provided, however, that no amendment or adjustment to an Option that would materially and adversely affect the rights of any Optionee shall be made without the prior written consent of the Optionee; 

(ix) to adjust the vesting of an Option held by an Employee or Consultant as a result of a change in the terms or conditions under which such
person is providing services to the Company; 
 (x) to construe and interpret the terms of the Plan and awards granted under the Plan,
which constructions, interpretations, and decisions shall be final and binding on all Participants; 
 (xi) to make any adjustment or
amendment to the Plan or to an outstanding award with or without a Participant’s consent if such adjustment or amendment is necessary to avoid the Company’s incurring adverse accounting charges; and 

(xii) in order to fulfill the purposes of the Plan and without amending the Plan, to modify grants of Options or Stock Purchase Rights to
Participants who are foreign nationals or employed outside of the United States in order to recognize differences in local law, tax policies, or customs. 

5. Eligibility. 

(a) Recipients of Grants. Nonstatutory Stock Options and Stock Purchase Rights may be granted to Employees and
Consultants. Incentive Stock Options may be granted only to Employees; provided, however, that Employees of Affiliates shall not be eligible to receive Incentive Stock Options. 

(b) Type of Option. Each Option shall be designated in the Option Agreement as either an Incentive Stock Option or a
Nonstatutory Stock Option. 
 (c) ISO $100,000 Limitation. Notwithstanding any designation under Section 5(b), to
the extent that the aggregate Fair Market Value of Shares with respect to which Options designated as Incentive Stock Options are exercisable for the first time by any Optionee during any calendar year (under all plans of the Company or any Parent
or Subsidiary) exceeds One Hundred Thousand Dollars ($100,000), such excess Options shall be treated as Nonstatutory Stock Options. For purposes of this Section 5(c), Incentive Stock Options shall be taken into account in the order in which
they were granted, and the Fair Market Value of the Shares subject to an Incentive Stock Option shall be determined as of the date of the grant of such Option. 

 (d) No Employment Rights. The Plan shall not confer upon any Participant any
right with respect to continuation of an employment or consulting relationship with the Company, nor shall it interfere in any way with such Participant’s right or the Company’s right to terminate his or her employment or consulting
relationship at any time, with or without Cause. 
 6. Term of Plan. The Plan shall become effective upon its adoption
by the Board of Directors. It shall continue in effect for a term of ten (10) years unless sooner terminated under Section 15 of the Plan. 

7. Term of Option. The term of each Option shall be the term stated in the Option Agreement; provided, however,
that the term shall be no more than ten (10) years from the date of grant thereof or such shorter term as may be provided in the Option Agreement; and provided further however, that, in the case of an Incentive Stock Option granted to a
person who at the time of such grant is a Ten Percent Holder, the term of the Option shall be five (5) years from the date of grant thereof or such shorter term as may be provided in the Option Agreement. 

8. Option Exercise Price and Consideration. 

(a) Exercise Price. The per Share exercise price for the Shares to be issued pursuant to exercise of an Option shall be
such price as is determined by the Administrator, subject to compliance with Section 409A of the Code, and set forth in the Option Agreement, but shall be subject to the following: 

(i) In the case of an Incentive Stock Option 

(A) granted to an Employee who at the time of grant is a Ten Percent Holder, the per Share exercise price shall be no less than one hundred
ten percent (110%) of the Fair Market Value per Share on the date of grant; or 
 (B) granted to any other Employee, the per Share exercise
price shall be no less than one hundred percent (100%) of the Fair Market Value per Share on the date of grant. 
 (ii) In the case of a
Nonstatutory Stock Option 
 (A) granted prior to the date, if any, on which the Common Stock becomes a Listed Security to a person who is
at the time of grant is a Ten Percent Holder, the per Share exercise price shall be no less than one hundred ten percent (110%) of the Fair Market Value per Share on the date of grant if required by the Applicable Laws and, if not so required, shall
be such price as is determined by the Administrator; 
 (B) granted prior to the date, if any, on which the Common Stock becomes a Listed
Security to any other eligible person, the per Share exercise price shall be no less than the Fair Market Value per Share on the date of grant if required by the Applicable Laws and, if not so required, shall be such price as is determined by the
Administrator. 
 (C) granted on or after the date, if any, on which the Common Stock becomes a Listed Security to any eligible person, the
per share Exercise Price shall be such price as determined by the Administrator provided that if such eligible person is, at the time of the grant of such Option, a Named Executive of the Company, the per share Exercise Price shall be no less than
one hundred percent (100%) of the Fair Market Value on the date of grant if such Option is intended to qualify as performance-based compensation under Section 162(m) of the Code. 

 (iii) Notwithstanding the foregoing, Options may be granted with a per Share exercise price
other than as required above pursuant to a merger or other corporate transaction. 
 (b) Permissible Consideration. The
consideration to be paid for the Shares to be issued upon exercise of an Option, including the method of payment, shall be determined by the Administrator (and, in the case of an Incentive Stock Option, shall be determined at the time of grant) and
may consist entirely of (1) cash; (2) check; (3) delivery of Optionee’s full recourse promissory note with such interest, security, and redemption provisions as the Administrator determines to be appropriate;
(4) cancellation of indebtedness; (5) other Shares that have a Fair Market Value on the date of surrender equal to the aggregate exercise price of the Shares as to which the Option is exercised; provided, however, that in the case
of Shares acquired, directly or indirectly, from the Company, such Shares must have been owned by the Optionee for more than six (6) months on the date of surrender (or such other period as may be required to avoid the Company’s incurring
an adverse accounting charge); (6) delivery of a properly executed exercise notice together with such other documentation as the Administrator and a securities broker approved by the Company shall require to effect exercise of the Option and
prompt delivery to the Company of the sale or loan proceeds required to pay the exercise price and any applicable withholding taxes; or (7) any combination of the foregoing methods of payment. In making its determination as to the type of
consideration to accept, the Administrator shall consider if acceptance of such consideration may be reasonably expected to benefit the Company and the Administrator may, in its sole discretion, refuse to accept a particular form of consideration at
the time of any Option exercise. 
 9. Exercise of Option. 

(a) General. 

(i) Exercisability. Any Option granted hereunder shall be exercisable at such times and under such conditions as
determined by the Administrator, consistent with the term of the Plan and reflected in the Option Agreement, including vesting requirements and/or performance criteria with respect to the Company and/or the Optionee; provided, however, that,
if required by the Applicable Laws, any Option granted prior to the date, if any, upon which the Common Stock becomes a Listed Security shall become exercisable at the rate of at least twenty percent (20%) per year over five (5) years from the date
the Option is granted. In the event that any of the Shares issued upon exercise of an Option (which exercise occurs prior to the date, if any, upon which the Common Stock becomes a Listed Security) should be subject to a right of repurchase in the
Company’s favor, such repurchase right shall, if required by the Applicable Laws, lapse at the rate of at least twenty percent (20%) per year over five (5) years from the date the Option is granted. Notwithstanding the above, in the case
of an Option granted to an officer, Director, or Consultant of the Company or any Parent, Subsidiary, or Affiliate of the Company, the Option may become fully exercisable, or a repurchase right, if any, in favor of the Company shall lapse, at any
time or during any period established by the Administrator. The Administrator shall have the discretion to determine whether and to what extent the vesting of Options shall be tolled during any unpaid leave of absence; provided, however, that
in the absence of such determination, vesting of Options shall be tolled during any such leave. 
 (ii) Minimum Exercise
Requirements. An Option may not be exercised for a fraction of a Share. The Administrator may require that an Option be exercised as to a minimum number of Shares, provided that such requirement shall not prevent an Optionee from
exercising the full number of Shares as to which the Option is then exercisable. 
 (iii) Procedures for and Results of
Exercise. An Option shall be deemed exercised when written notice of such exercise has been given to the Company in accordance with the terms of the Option by the person entitled to exercise the Option and the Company has received
full 

 
payment for the Shares with respect to which the Option is exercised. Full payment may, as authorized by the Administrator, consist of any consideration and method of payment allowable under
Section 8(b) of the Plan; provided, however, that the Administrator may, in its sole discretion, refuse to accept any form of consideration at the time of any Option exercise. 

Exercise of an Option in any manner shall result in a decrease in the number of Shares that thereafter may be 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. 
 (iv) 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 Optioned Stock, notwithstanding the exercise of the Option. No adjustment will be made for a dividend or other right for which the record date is prior to the date the stock certificate is issued, except
as provided in Section 13 of the Plan. 
 (b) Termination of Employment or Consulting Relationship. Upon
termination of an Optionee’s employment or consulting relationship with the Company, the Company will have the right, in its sole discretion, to repurchase an Optionee’s vested and exercised Shares by providing Optionee written notice
within six (6) months of the expiration of such Optionee’s ability to exercise an Option as set forth in Sections 9(b)(i-iii) below (the “Repurchase Right”). If the Company exercises its Repurchase Right, it will pay such
Optionee a price equal to the Fair Market Value of his or her vested and exercised Shares as of the date of such Optionee’s termination of employment or consulting relationship with the Company (the “Repurchase Price”). The
Company will pay the Repurchase Price to the Optionee in twenty-four (24) equal monthly installments beginning on the date the Company exercises its Repurchase Right. Except as otherwise set forth in this Section 9(b), the Administrator
shall establish and set forth in the applicable Option Agreement the terms and conditions upon which an Option shall remain exercisable, if at all, following termination of an Optionee’s Continuous Service Status, which provisions may be waived
or modified by the Administrator at any time. To the extent that the Optionee is not entitled to exercise an Option at the date of his or her termination of Continuous Service Status, or if the Optionee (or other person entitled to exercise the
Option) does not exercise the Option to the extent so entitled within the time specified in the Option Agreement or below (as applicable), the Option shall terminate and the Optioned Stock underlying the unexercised portion of the Option shall
revert to the Plan. In no event may any Option be exercised after the expiration of the Option term as set forth in the Option Agreement (and subject to Section 7). 

The following provisions (1) shall apply to the extent an Option Agreement does not specify the terms and conditions upon which an Option
shall terminate upon termination of an Optionee’s Continuous Service Status, and (2) establish the minimum post-termination exercise periods that may be set forth in an Option Agreement: 

(i) Termination other than Upon Disability or Death or for Cause. In the event of termination of an Optionee’s
Continuous Service Status, such Optionee may exercise an Option for ninety (90) days following such termination to the extent the Optionee was entitled to exercise it at the date of such termination. No termination shall be deemed to occur and
this Section 9(b)(i) shall not apply if (i) the Optionee is a Consultant who becomes an Employee, or (ii) the Optionee is an Employee who becomes a Consultant. 

(ii) Disability of Optionee. In the event of termination of an Optionee’s Continuous Service Status as a result of
his or her disability (including a disability within the meaning of Section 22(e)(3) of the Code), such Optionee may exercise an Option at any time within six (6) months following such termination to the extent the Optionee was entitled to
exercise it at the date of such termination. 

 (iii) Death of Optionee. In the event of the death of an Optionee during
the period of Continuous Service Status since the date of grant of the Option, or within thirty (30) days following termination of Optionee’s Continuous Service Status, the Option may be exercised by Optionee’s estate or by a person
who acquired the right to exercise the Option by bequest or inheritance at any time within twelve (12) months following the date of death, but only to the extent of the right to exercise that had accrued at the date of death or, if earlier, the
date the Optionee’s Continuous Service Status terminated. 
 (c) Buyout Provisions. The Administrator may at any
time offer to buy out for a payment in cash or Shares an Option previously granted under the Plan based on such terms and conditions as the Administrator shall establish and communicate to the Optionee at the time that such offer is made. 

10. Stock Purchase Rights. 

(a) Rights to Purchase. When the Administrator determines that it will offer Stock Purchase Rights under the Plan, it
shall advise the offeree in writing of the terms, conditions, and restrictions related to the offer, including the number of Shares that such person shall be entitled to purchase, the price to be paid, and the time within which such person must
accept such offer. In the case of a Stock Purchase Right granted prior to the date, if any, on which the Common Stock becomes a Listed Security and if required by the Applicable Laws at that time, the purchase price of Shares subject to such Stock
Purchase Rights shall not be less than one hundred percent (100%) of the Fair Market Value of the Shares as of the date of the offer. If the Applicable Laws do not impose the requirements set forth in the preceding sentence and with respect to any
Stock Purchase Rights granted after the date, if any, on which the Common Stock becomes a Listed Security, the purchase price of Shares subject to Stock Purchase Rights shall be as determined by the Administrator. The offer to purchase Shares
subject to Stock Purchase Rights shall be accepted by execution of a Restricted Stock Purchase Agreement in the form determined by the Administrator. 

(b) Repurchase Option. Unless the Administrator determines otherwise, the Restricted Stock Purchase Agreement shall grant the
Company a repurchase option exercisable upon the voluntary or involuntary termination of the purchaser’s employment with the Company for any reason (including death or disability). The purchase price for Shares repurchased pursuant to the
Restricted Stock Purchase Agreement shall be the original purchase price paid by the purchaser and may be paid by cancellation of any indebtedness of the purchaser to the Company. The repurchase option shall lapse at such rate as the Administrator
may determine, provided that with respect to a Stock Purchase Right granted prior to the date, if any, on which the Common Stock becomes a Listed Security to a purchaser who is not an officer, Director or Consultant of the Company or of any Parent
or Subsidiary of the Company, it shall lapse at a minimum rate of twenty percent (20%) per year if required by the Applicable Laws. 
 (c)
Other Provisions. The Restricted Stock Purchase Agreement shall contain such other terms, provisions, and conditions not inconsistent with the Plan as may be determined by the Administrator in its sole discretion. In addition,
the provisions of Restricted Stock Purchase Agreements need not be the same with respect to each purchaser. 
 (d) Rights as a
Stockholder. Once the Stock Purchase Right is exercised, the purchaser shall have the rights equivalent to those of a stockholder, and shall be a stockholder when his or 

 
her purchase is entered upon the records of the duly authorized transfer agent of the Company. No adjustment will be made for a dividend or other right for which the record date is prior to the
date the Stock Purchase Right is exercised, except as provided in Section 13 of the Plan. 
 11. Taxes. 

(a) As a condition of the exercise of an Option or Stock Purchase Right granted under the Plan, the Participant (or in the case of the
Participant’s death, the person exercising the Option or Stock Purchase Right) shall make such arrangements as the Administrator may require for the satisfaction of any applicable federal, state, local or foreign withholding tax obligations
that may arise in connection with the exercise of the Option or Stock Purchase Right and the issuance of Shares. The Company shall not be required to issue any Shares under the Plan until such obligations are satisfied. If the Administrator allows
the withholding or surrender of Shares to satisfy a Participant’s tax withholding obligations under this Section 11 (whether pursuant to Section 11(c), (d) or (e), or otherwise), the Administrator shall not allow Shares to be withheld
in an amount that exceeds the minimum statutory withholding rates for federal and state tax purposes, including payroll taxes. 
 (b) In the
case of an Employee and in the absence of any other arrangement, the Employee shall be deemed to have directed the Company to withhold or collect from his or her compensation an amount sufficient to satisfy such tax obligations from the next payroll
payment otherwise payable after the date of an exercise of the Option or Stock Purchase Right. 
 (c) This Section 11(c) shall apply
only after the date, if any, upon which the Common Stock becomes a Listed Security. In the case of Participant other than an Employee (or in the case of an Employee where the next payroll payment is not sufficient to satisfy such tax obligations,
with respect to any remaining tax obligations), in the absence of any other arrangement and to the extent permitted under the Applicable Laws, the Participant shall be deemed to have elected to have the Company withhold from the Shares to be issued
upon exercise of the Option or Stock Purchase Right that number of Shares having a Fair Market Value determined as of the applicable Tax Date (as defined below) equal to the amount required to be withheld. For purposes of this Section 11, the
Fair Market Value of the Shares to be withheld shall be determined on the date that the amount of tax to be withheld is to be determined under the Applicable Laws (the “Tax Date”). 

(d) If permitted by the Administrator, in its discretion, a Participant may satisfy his or her tax withholding obligations upon exercise of an
Option or Stock Purchase Right by surrendering to the Company Shares that have a Fair Market Value determined as of the applicable Tax Date equal to the amount required to be withheld. In the case of shares previously acquired from the Company that
are surrendered under this Section 11(d), such Shares must have been owned by the Participant for more than six (6) months on the date of surrender (or such other period of time as is required for the Company to avoid adverse accounting
charges). 
 (e) Any election or deemed election by a Participant to have Shares withheld to satisfy tax withholding obligations under
Section 11(c) or (d) above shall be irrevocable as to the particular Shares as to which the election is made and shall be subject to the consent or disapproval of the Administrator. Any election by a Participant under Section 11(d)
above must be made on or prior to the applicable Tax Date. 
 (f) In the event an election to have Shares withheld is made by a Participant
and the Tax Date is deferred under Section 83 of the Code because no election is filed under Section 83(b) of the Code, the Participant shall receive the full number of Shares with respect to which the Option or Stock Purchase Right is
exercised but such Participant shall be unconditionally obligated to tender back to the Company the proper number of Shares on the Tax Date. 

 12. Non-Transferability of Options and Stock
Purchase Rights. 
 (a) General. Except as set forth in this Section 12, Options and Stock Purchase Rights
may not be sold, pledged, assigned, hypothecated, transferred, or disposed of in any manner other than by will or by the laws of descent or distribution. The designation of a beneficiary by an Optionee will not constitute a transfer. An Option or
Stock Purchase Right may be exercised, during the lifetime of the holder of an Option or Stock Purchase Right, only by such holder or a transferee permitted by this Section 12. 

(b) Limited Transferability Rights. Notwithstanding anything else in this Section 12, prior to the date, if any, on
which the Common Stock becomes a Listed Security, the Administrator may in its discretion grant Nonstatutory Stock Options that may be transferred by instrument to an inter vivos or testamentary trust in which the Options are to be passed to
beneficiaries upon the death of the trustor (settlor) or by gift to “Immediate Family” (as defined below), on such terms and conditions as the Administrator deems appropriate. Following the date, if any, on which the Common Stock
becomes a Listed Security, the Administrator may in its discretion grant transferable Nonstatutory Stock Options pursuant to Option Agreements specifying the manner in which such Nonstatutory Stock Options are transferable. “Immediate
Family” means any child, stepchild, grandchild, parent, stepparent, grandparent, spouse, sibling, mother-in-law, father-in-law, son-in-law, daughter-in-law, brother-in-law, or sister-in-law, and shall include adoptive relationships. 

13. Adjustments Upon Changes in Capitalization, Merger or Certain Other Transactions. 

(a) Changes in Capitalization. Subject to any required action by the stockholders of the Company, the number of Shares of
Common Stock covered by each outstanding Option or Stock Purchase Right, and the number of Shares of Common Stock that have been authorized for issuance under the Plan but as to which no Options or Stock Purchase Rights have yet been granted or that
have been returned to the Plan upon cancellation or expiration of an Option or Stock Purchase Right, as well as the price per Share of Common Stock covered by each such outstanding Option or Stock Purchase Right, shall be proportionately adjusted
for any increase or decrease in the number of issued Shares of Common Stock resulting from a stock split, reverse stock split, stock dividend, combination, recapitalization, or reclassification of the Common Stock, or any other increase or decrease
in the number of issued Shares of Common Stock effected without receipt of consideration by the Company; provided, however, that conversion of any convertible securities of the Company shall not be deemed to have been “effected without
receipt of consideration.” Such adjustment shall be made by the Administrator, whose determination in that respect shall be final, binding, and conclusive. Except as expressly provided herein, no issuance by the Company of shares of stock
of any class, or securities convertible into shares of stock of any class, shall affect, and no adjustment by reason thereof shall be made with respect to, the number or price of Shares of Common Stock subject to an Option or Stock Purchase Right.

 (b) Dissolution or Liquidation. In the event of the dissolution or liquidation of the Company, each Option and Stock
Purchase Right will terminate immediately prior to the consummation of such action, unless otherwise determined by the Administrator. 
 (c)
Corporate Transaction. In the event of a Corporate Transaction, outstanding Options and Shares acquired under the Plan shall be subject to the agreement of the Corporate Transaction, which need not treat all outstanding Options
in an identical manner. Such agreement, 

 
without the Optionees’ consent, may dispose of Options that are not exercisable as of the effective date of such Corporate Transaction in any manner permitted by applicable law, including
(without limitation) the cancellation of such Options without the payment of any consideration. Such agreement, without the Optionees’ consent, shall provide for one or more of the following with respect to Options that are exercisable as of
the effective date of such Corporate Transaction. 
 (i) The continuation of such Options by the Company (if the Company is the surviving
corporation). 
 (ii) The assumption of such Options by the surviving corporation or its parent in a manner that complies with
Section 424(a) of the Code (whether or not such Options are Incentive Stock Options). 
 (iii) The substitution by the surviving
corporation or its parent of new options for such Options in a manner that complies with Section 424(a) of the code (whether or not such Options are Incentive Stock Options). 

(iv) The cancellation of such Options and a payment to the Optionees equal to the excess of (A) the Fair Market Value of the Shares
subject to such Options as of the effective date of such Corporate Transaction over (B) their Exercise Price. Such payment shall be made in the form of cash, cash equivalents, or securities of the surviving corporation or its parent with a Fair
Market Value equal to the required amount. 
 (v) The cancellation of such Options. 

With the consent of the Administrator, or if appropriate, the consent of the Company’s successor entity, Options and Shares acquired
under the Plan may be subject to additional acceleration of vesting and exercisability upon or after a Corporate Transaction as may be provided in any Stock Option Agreement (including in any notice of stock option grant), Restricted Stock Purchase
Agreement, or as may be provided in any other written agreement between the Company or any or successor thereto, if appropriate, but in the absence of such provision, no such acceleration shall occur. Any exercise of such Options prior to the
closing date of such Corporate Transaction may be contingent on the closing of such Corporate Transaction. 
 (d) Certain
Distributions. In the event of any distribution to the Company’s stockholders of securities of any other entity or other assets (other than dividends payable in cash or stock of the Company) without receipt of consideration by
the Company, the Administrator may, in its discretion, appropriately adjust the price per Share of Common Stock covered by each outstanding Option or Stock Purchase Right to reflect the effect of such distribution. 

14. Time of Granting Options and Stock Purchase Rights. The date of grant of an Option or Stock Purchase Right shall, for
all purposes, be the date on which the Administrator makes the determination granting such Option or Stock Purchase Right, or such other date as is determined by the Administrator; provided, however, that in the case of any Incentive Stock
Option, the grant date shall be the later of the date on which the Administrator makes the determination granting such Incentive Stock Option or the date of commencement of the Optionee’s employment relationship with the Company. Notice of the
determination shall be given to each Employee or Consultant to whom an Option or Stock Purchase Right is so granted within a reasonable time after the date of such grant. 

 15. Amendment and Termination of the Plan. 

(a) Authority to Amend or Terminate. The Board may at any time amend, alter, suspend or discontinue the Plan, but no
amendment, alteration, suspension or discontinuation (other than an adjustment pursuant to Section 13 above) shall be made that would materially and adversely affect the rights of any Optionee or holder of Stock Purchase Rights under any
outstanding grant, without his or her consent. In addition, to the extent necessary and desirable to comply with the Applicable Laws, the Company shall obtain stockholder approval of any Plan amendment in such a manner and to such a degree as
required. 
 (b) Effect of Amendment or Termination. No amendment or termination of the Plan shall materially and
adversely affect Options or Stock Purchase Rights already granted, unless mutually agreed otherwise between the Optionee or holder of the Stock Purchase Rights and the Administrator, which agreement must be in writing and signed by the Optionee or
holder and the Company. 
 (c) Accounting Issues. Notwithstanding anything else to the contrary in this
Section 15, the Administrator may at any time amend or adjust the Plan or an outstanding award issued under the Plan without the consent of the affected Participant(s) if such amendment or adjustment is necessary to avoid the Company’s
incurring adverse accounting charges. 
 16. Conditions Upon Issuance of Shares. Notwithstanding any other provision of
the Plan or any agreement entered into by the Company pursuant to the Plan, the Company shall not be obligated, and shall have no liability for failure, to issue or deliver any Shares under the Plan unless such issuance or delivery would comply with
the Applicable Laws, with such compliance determined by the Company in consultation with its legal counsel. As a condition to the exercise of an Option or Stock Purchase Right, the Company may require the person exercising the 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 by
law. 
 17. Reservation of Shares. The Company, during the term of this Plan, will at all times reserve and keep
available such number of Shares as shall be sufficient to satisfy the requirements of the Plan. 
 18. Agreements.
Options and Stock Purchase Rights shall be evidenced by Option Agreements and Restricted Stock Purchase Agreements, respectively, in such form(s) as the Administrator shall from time to time approve. 

19. Stockholder Approval. If required by the Applicable Laws, continuance of the Plan shall be subject to approval by the
stockholders of the Company within twelve (12) months before or after the date the Plan is adopted. Such stockholder approval shall be obtained in the manner and to the degree required under the Applicable Laws. 

20. Information and Documents to Optionees and Purchasers. Prior to the date, if any, upon which the Common Stock becomes
a Listed Security and if required by the Applicable Laws, the Company shall provide financial statements at least annually to each Optionee and to each individual who acquired Shares pursuant to the Plan, during the period such Optionee or purchaser
has one or more Options or Stock Purchase Rights outstanding, and in the case of an individual who acquired Shares pursuant to the Plan, during the period such individual owns such Shares. The Company shall not be required to provide such
information if the issuance of Options or Stock Purchase Rights under the Plan is limited to key employees whose duties in connection with the Company assure their access to equivalent information. 

 AMENDMENT NO. 1 TO THE ALPINE IMMUNE SCIENCES, INC. 

AMENDED AND RESTATED 2015 STOCK PLAN 

This Amendment No. 1 to the Alpine Immune Sciences, Inc. Amended and Restated 2015 Stock Plan (this “Amendment”) is made
effective as of March 29, 2017 by Alpine Immune Sciences, Inc., a Delaware corporation (the “Company”) to amend that certain Alpine Immune Sciences, Inc. Amended and Restated 2015 Stock Plan (the “Plan”).
Capitalized terms used herein and not defined shall have the meanings given to them in the Plan. 
 RECITALS 

WHEREAS: The board of directors (the “Board”) and stockholders (the “Stockholders”) of the
Company, have approved the existing Plan; and 
 WHEREAS: the Board, on March 29, 2017, and the Stockholders, on
April 11, 2017, have each approved an amendment to the Plan to increase the maximum aggregate number of Shares that may be sold under the Plan by 1,050,669 Shares (from 2,394,935 Shares to 3,445,604 Shares), as set forth below in this
Amendment. 
 AMENDMENT 
 NOW,
THEREFORE, the Plan is hereby amended as follows: 
 1. The first sentence of Section 3 of the Plan is hereby amended and restated in its entirety
to read as follows: 
 “Subject to the provisions of Section 13 of the Plan, the maximum aggregate number of Shares that may be
sold under the Plan is three million four hundred forty-five thousand six hundred four (3,445,604) Shares.” 
 2. Except as modified herein, the
provisions of the Plan shall remain unchanged and in full force and effect. 
 ***EX-4.2

 Exhibit 4.2 

ALPINE IMMUNE SCIENCES, INC. 

AMENDED AND RESTATED 2015 STOCK PLAN 

STOCK OPTION AGREEMENT 

1. Grant of Option. Alpine Immune Sciences, Inc., a Delaware corporation (the “Company”), hereby grants to
            (the “Optionee”), an option (this “Option”) to purchase a total number of shares of Common Stock (the “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”) subject to the terms, definitions, and provisions of the Alpine Immune Sciences, Inc. Amended and
Restated 2015 Stock Plan (the “Plan”) adopted by the Company, which is incorporated herein by reference. Unless otherwise defined herein, the terms defined in the Plan shall have the same defined meanings in this Option. 

If designated an Incentive Stock Option in the Notice of Stock Option Grant, this Option is intended to qualify as an Incentive Stock Option
as defined in Section 422 of the Code. 
 2. Exercise of Option. 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 provisions of Section 9 of the Plan as follows: 

 (a) Right to Exercise. 

(i) This Option may not be exercised for a fraction of a share. 

(ii) In the event of Optionee’s death, disability, or other termination of employment, the exercisability of the Option is governed by
Sections 5, 6, and 7 below, subject to the limitation contained in Section 2(a)(i). 
 (iii) In no event may this Option be
exercised after the date of expiration of the Term of this Option as set forth in the Notice of Stock Option Grant. 
 (b) Method of
Exercise. This Option shall be exercisable by execution and delivery of the Exercise Notice and Restricted Stock Purchase Agreement attached hereto as Exhibit A (the “Exercise Agreement”) or of any other form of
written notice approved for such purpose by the Company which shall state the election to exercise the Option, the number of Shares in respect of which the Option is being exercised, and such other representations and agreements as to the
holder’s investment intent with respect to such shares of Common Stock as may be required by the Company pursuant to the provisions of the Plan. Such written notice shall be signed by Optionee and shall be delivered in person or by certified
mail to the Secretary of the Company. The written notice shall be accompanied by payment of the Exercise Price. This Option shall be deemed to be exercised upon receipt by the Company of such written notice accompanied by the Exercise Price. 

No Shares will be issued pursuant to the exercise of an Option unless such issuance and such exercise shall comply with all relevant
provisions of applicable law and the requirements of any stock exchange upon which the Shares may then be listed. Assuming such compliance, for income tax purposes the Shares shall be considered transferred to Optionee on the date on which the
Option is exercised with respect to such Shares. 
 3. Method of Payment. Payment of the Exercise Price shall be by any of the
following, or a combination thereof, at the election of Optionee: 
 (a) cash or check; 

(b) cancellation of indebtedness; 

(c) surrender of other shares of Common Stock of the Company which (i) in the case of Shares acquired pursuant to the exercise of a
Company option, have been owned by Optionee for more than six (6) months on the date of surrender, and (ii) have a fair market value on the date of surrender equal to the Exercise Price of the Shares as to which the Option is being
exercised; 
 (d) if there is a public market for the Shares and they are registered under the Securities Act of 1933, as amended from time
to time, delivery of a properly executed exercise notice together with irrevocable instructions to a broker to deliver promptly to the Company the amount of sale or loan proceeds required to pay the exercise price; or 

(e) non-recourse indebtedness secured by the Shares, so long as such indebtedness is approved by the Administrator. 

4. 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 federal or state securities or other law or regulation, including any rule
under Part 207 of Title 12 of the Code of Federal Regulations as promulgated by the Federal Reserve Board. As a condition to the exercise of this Option, the Company may require Optionee to make any representation and warranty to the
Company as may be required by any applicable law or regulation. 

 5. Termination of Relationship. In the event of termination of Optionee’s
Continuous Status as an Employee or Consultant, Optionee may, to the extent otherwise so entitled at the date of such termination (the “Termination Date”), exercise this Option during the Termination Period set forth in the Notice
of Stock Option Grant. To the extent that Optionee was not entitled to exercise this Option at such Termination Date, or if Optionee does not exercise this Option within the Termination Period, the Option shall terminate. The Company will have the
right, in its sole discretion, to repurchase any of the Optionee’s exercised Shares (to the extent so entitled) as set forth in the Plan. 

6. Disability of Optionee. Notwithstanding the provisions of Section 5 above, in the event of termination of Continuous
Status as an Employee or Consultant as a result of Optionee’s total and permanent disability (as defined in Section 22(e)(3) of the Code), Optionee may, but only within six (6) months from the Termination Date (but in no event later
than the Expiration Date set forth in the Notice of Stock Option Grant), exercise this Option to the extent Optionee was entitled to exercise it as of such Termination Date. To the extent that Optionee was not entitled to exercise the Option as of
the Termination Date, or if Optionee does not exercise such Option (to the extent so entitled) within the time specified in this Section 6(a), the Option shall terminate. The Company will have the right, in its sole discretion, to repurchase
any of the Optionee’s exercised Shares (to the extent so entitled) as set forth in the Plan. 
 7. Death of Optionee. In
the event of the death of Optionee (a) during the Term of this Option and while an Employee or Consultant of the Company and having been in Continuous Status as an Employee or Consultant since the date of grant of the Option, or (b) within
thirty (30) days after Optionee’s Termination Date, the Option may be exercised at any time within twelve (12) months following the date of death (but in no event later than the Expiration Date set forth in the Notice of Stock Option
Grant), by Optionee’s estate or by a person who acquired the right to exercise the Option by bequest or inheritance, but only to the extent of the right to exercise that had accrued at the Termination Date. The Company will have the right, in
its sole discretion, to repurchase any of the Optionee’s exercised Shares (to the extent so entitled) as set forth in the Plan. 
 8.
Non-Transferability of Option. 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 Optionee only by him or her. The terms of this
Option shall be binding upon the executors, administrators, heirs, successors and assigns of Optionee. 
 9. Term of Option.
This Option may be exercised only within the Term set forth in the Notice of Stock Option Grant, subject to the limitations set forth in Section 7 of the Plan. 

10. Tax Consequences. Set forth below is a brief summary as of the date of this Option of certain of the federal tax consequences
of exercise of this Option and disposition of the Shares under the laws in effect as of the Date of Grant. THIS SUMMARY IS NECESSARILY INCOMPLETE AND DOES NOT ADDRESS STATE TAX IMPLICATIONS OF OPTIONS GRANTED UNDER THE PLAN. IN ADDITION, THE TAX
LAWS AND REGULATIONS ARE SUBJECT TO CHANGE IN WAYS THAT COULD MAKE THE FOLLOWING DISCLOSURE OBSOLETE. OPTIONEE SHOULD CONSULT A TAX ADVISER BEFORE EXERCISING THIS OPTION OR DISPOSING OF THE SHARES. 

 (a) Exercise of Incentive Stock Option. If this Option qualifies as an Incentive
Stock Option, there will be no regular federal income tax liability upon the exercise of the Option, although the excess, if any, of the fair market value of the Shares on the date of exercise over the Exercise Price will be treated as an adjustment
to the alternative minimum tax for federal tax purposes and may subject Optionee to the alternative minimum tax in the year of exercise. 

(b) Exercise of Nonstatutory Stock Option. If this Option does not qualify as an Incentive Stock Option, there may be a regular
federal income tax liability upon the exercise of the Option. Optionee will be treated as having received compensation income (taxable at ordinary income tax rates) equal to the excess, if any, of the fair market value of the Shares on the date of
exercise over the Exercise Price. If Optionee is an employee, the Company will be required to withhold from Optionee’s compensation or collect from Optionee and pay to the applicable taxing authorities an amount equal to a percentage of this
compensation income at the time of exercise. 
 (c) Disposition of Shares. In the case of a Nonstatutory Stock Option, if
Shares are held for at least one (1) year, any gain realized on disposition of the Shares will be treated as long-term capital gain for federal income tax purposes. In the case of an Incentive Stock Option, if Shares transferred pursuant to the
Option are held for at least one (1) year after exercise and are disposed of at least two (2) years after the Date of Grant, any gain realized on disposition of the Shares will also be treated as long-term capital gain for federal income
tax purposes. If Shares purchased under an Incentive Stock Option are disposed of within such one (1)-year period or within two (2) years after the Date of Grant, any gain realized on such disposition will be treated as compensation income
(taxable at ordinary income rates) to the extent of the difference between the Exercise Price and the lesser of (i) the fair market value of the Shares on the date of exercise, or (ii) the sale price of the Shares. 

(d) Notice of Disqualifying Disposition of Incentive Stock Option Shares. If the Option granted to Optionee herein is an
Incentive Stock Option, and if Optionee sells or otherwise disposes of any of the Shares acquired pursuant to the Incentive Stock Option 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, Optionee shall immediately notify the Company in writing of such disposition. Optionee acknowledges and agrees that he or she may be subject to income tax withholding by the Company on the compensation
income recognized by Optionee from the early disposition by payment in cash or out of the current earnings paid to Optionee. 
 11.
Withholding Tax Obligations. Optionee understands that, upon exercising a Nonstatutory Stock Option, he or she will recognize income for tax purposes in an amount equal to the excess of the then fair market value of the Shares over the
Exercise Price. However, the timing of this income recognition may be deferred for up to six (6) months if Optionee is subject to Section 16 of the Securities Exchange Act of 1934, as amended from time to time (the “Exchange
Act”). If Optionee is an employee, the Company will be required to withhold from Optionee’s compensation, or collect from Optionee and pay to the applicable taxing authorities an amount equal to a percentage of this compensation
income. Additionally, Optionee may at some point be required to satisfy tax withholding obligations with respect to the disqualifying disposition of an Incentive Stock Option. Optionee shall satisfy his or her tax withholding obligation arising upon
the exercise of this Option by one or some combination of the following methods: (a) by cash payment, (b) out of Optionee’s current compensation, (c) if permitted by the Administrator, in its discretion, by surrendering to the
Company Shares which (i) in the case of Shares previously acquired from the Company, have been owned by Optionee for more than six months on the date of surrender, and (ii) have a fair market value on the date of surrender equal to the
minimum statutory withholding amount, or (d) by electing to have the Company withhold from the Shares to be issued upon exercise of the Option that number of Shares having a fair market value equal to the minimum statutory withholding amount.
For this purpose, the fair market value of the Shares to be withheld shall be determined on the date that the amount of tax to be withheld is to be determined (the “Tax Date”). 

 If Optionee is subject to Section 16 of the Exchange Act (an “Insider”),
any surrender of previously owned Shares to satisfy tax withholding obligations arising upon exercise of this Option must comply with the applicable provisions of Rule 16b-3 promulgated under the Exchange Act
(“Rule 16b-3”). 
 All elections by Optionee to have Shares withheld to satisfy tax withholding obligations shall be made
in writing in a form acceptable to the Administrator and shall be subject to the following restrictions: 
 (a) the election must be made on
or prior to the applicable Tax Date; 
 (b) once made, the election shall be irrevocable as to the particular Shares of the Option as to
which the election is made; and 
 (c) all elections shall be subject to the consent or disapproval of the Administrator. 

12. Market Standoff Agreement. In connection with the initial public offering of the Company’s securities and upon request
of the Company or the underwriters managing any underwritten offering of the Company’s securities, Optionee hereby agrees not to sell, make any short sale of, loan, grant any option for the purchase of, or otherwise dispose of any Shares (other
than those included in the registration) without the prior written consent of the Company or such underwriters, as the case may be, for such period of time (not to exceed one hundred eighty (180) days) from the effective date of such
registration as may be requested by the Company or such managing underwriters and to execute an agreement reflecting the foregoing as may be requested by the underwriters at the time of the public offering. 

[Signature Page Follows] 

 This Agreement may be executed in two or more counterparts, each of which shall be deemed an
original and all of which together shall constitute one document. 
  

			
	 ALPINE IMMUNE SCIENCES, INC.,

a Delaware corporation

 
			
		
	By:	 	  

	Name:	 	  

	Its:	 	  

 OPTIONEE ACKNOWLEDGES AND AGREES THAT THE VESTING OF SHARES PURSUANT TO THE OPTION HEREOF IS EARNED ONLY
BY CONTINUING EMPLOYMENT OR CONSULTANCY AT THE WILL OF THE COMPANY (NOT THROUGH THE ACT OF BEING HIRED, BEING GRANTED THIS OPTION OR ACQUIRING SHARES HEREUNDER). OPTIONEE FURTHER ACKNOWLEDGES AND AGREES THAT NOTHING IN THIS AGREEMENT, NOR IN THE
COMPANY’S STOCK PLAN WHICH IS INCORPORATED HEREIN BY REFERENCE, SHALL CONFER UPON OPTIONEE ANY RIGHT WITH RESPECT TO CONTINUATION OF EMPLOYMENT OR CONSULTANCY BY THE COMPANY, NOR SHALL IT INTERFERE IN ANY WAY WITH OPTIONEE’S RIGHT OR THE
COMPANY’S RIGHT TO TERMINATE OPTIONEE’S EMPLOYMENT OR CONSULTANCY AT ANY TIME, WITH OR WITHOUT CAUSE. 
 Optionee 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. Optionee 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. Optionee 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. 
  

			
	Dated:
                                         
                                         
          	 	  

		 	Optionee
		 	

 EXHIBIT A 

ALPINE IMMUNE SCIENCES, INC. 

AMENDED AND RESTATED 2015 STOCK PLAN 

EXERCISE NOTICE AND RESTRICTED STOCK PURCHASE AGREEMENT 

This Exercise Notice and Restricted Stock Purchase Agreement (“Agreement”) is made as of
            , by and between Alpine Immune Sciences, Inc., a Delaware corporation (the “Company”), and
            (“Purchaser”). To the extent any capitalized terms used in this Agreement are not defined, they shall have the meaning ascribed to them in the Amended and
Restated 2015 Stock Plan. 
 1. Exercise of Option. Subject to the terms and conditions hereof, Purchaser hereby
elects to exercise his or her option to purchase             shares of the Common Stock (the “Shares”) of the Company under and pursuant to the Company’s Amended and
Restated 2015 Stock Plan (the “Plan”) and the Stock Option Agreement dated             , (the “Option Agreement”). The purchase price for the Shares shall
be $            per Share for a total purchase price of $            . The term “Shares” refers to the purchased
Shares and all securities received in replacement of the Shares or as stock dividends or splits, all securities received in replacement of the Shares in a recapitalization, merger, reorganization, exchange, or the like, and all new, substituted, or
additional securities or other properties to which Purchaser is entitled by reason of Purchaser’s ownership of the Shares. 
 2.
Time and Place of Exercise. The purchase and sale of the Shares under this Agreement shall occur at the principal office of the Company simultaneously with the execution and delivery of this Agreement in accordance with the provisions
of Section 2(b) of the Option Agreement. On such date, the Company will deliver to Purchaser a certificate representing the Shares to be purchased by Purchaser (which shall be issued in Purchaser’s name) against payment of the exercise
price therefor by Purchaser by (a) check made payable to the Company, (b) cancellation of indebtedness of the Company to Purchaser, (c) delivery of shares of the Common Stock of the Company in accordance with Section 3 of the
Option Agreement, or (d) by a combination of the foregoing. 
 3. Limitations on Transfer. In addition to any other
limitation on transfer created by applicable securities laws, Purchaser shall not assign, encumber, or dispose of any interest in the Shares except in compliance with the provisions below and applicable securities laws. 

(a) Right of First Refusal. Before any Shares held by Purchaser or any transferee of Purchaser (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 3(a) (the “Right of First Refusal”). 
 (i) 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 terms and conditions of each proposed sale or transfer. The Holder shall offer the Shares at
the same price (the “Offered Price”) and upon the same terms (or terms as similar as reasonably possible) to the Company or its assignee(s). 

 (ii) 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 (iii) below. 
 (iii) Purchase Price. The purchase price
(“Purchase Price”) for the Shares purchased by the Company or its assignee(s) under this Section 3(a) 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. 
 (iv)
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. 

(v) 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 3(a), then the Holder may sell or otherwise transfer such Shares to that Proposed Transferee at the Offered Price or at a higher price; provided,
however, that such sale or other transfer is consummated within sixty (60) days after the date of the Notice and provided further that any such sale or other transfer is effected in accordance with any applicable securities laws and the
Proposed Transferee agrees in writing that the provisions of this Section 3 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, or if the Holder proposes to change the price or other terms to make them more favorable to the Proposed Transferee, 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. 
 (vi) Exception for Certain Family
Transfers. Anything to the contrary contained in this Section 3(a) notwithstanding, the transfer of any or all of the Shares during Purchaser’s lifetime or on Purchaser’s death by will or intestacy to Purchaser’s
Immediate Family or a trust for the benefit of Purchaser’s Immediate Family shall be exempt from the provisions of this Section 3(a). “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, and there shall be no further transfer of such Shares except in
accordance with the terms of this Section 3. 
 (b) Involuntary Transfer.  

(i) Company’s Right to Purchase upon Involuntary Transfer. In the event, at any time after the date of this Agreement, of
any transfer by operation of law or other involuntary transfer (including death or divorce, but excluding a transfer to Immediate Family as set forth in Section 3(a)(vi) above) of all or a portion of the Shares by the record holder thereof, the
Company shall have an option to purchase all of the Shares transferred at the greater of the purchase price paid by Purchaser pursuant to this Agreement or the fair market value of the Shares on the date of transfer. Upon such a transfer, the person
acquiring the Shares shall promptly notify the Secretary of the Company of such transfer. The right to purchase such Shares shall be provided to the Company for a period of thirty (30) days following receipt by the Company of written notice by
the person acquiring the Shares. 

 (ii) Price for Involuntary Transfer. With respect to any stock to be transferred
pursuant to Section 3(b)(i), the price per Share shall be a price set by the Board of Directors of the Company that will reflect the current value of the stock in terms of present earnings and future prospects of the Company. The Company shall
notify Purchaser or his or her executor of the price so determined within thirty (30) days after receipt by it of written notice of the transfer or proposed transfer of Shares. However, if the Purchaser does not agree with the valuation as
determined by the board of directors of the Company, the Purchaser shall be entitled to have the valuation determined by an independent appraiser to be mutually agreed upon by the Company and the Purchaser and whose fees shall be borne equally by
the Company and the Purchaser. 
 (c) Assignment. The right of the Company to purchase any part of the Shares may be assigned
in whole or in part to any stockholders or stockholders of the Company or other persons or organizations. 
 (d) Restrictions Binding
on Transferees. All transferees of Shares or any interest therein will receive and hold such Shares or interest subject to the provisions of this Agreement. Any sale or transfer of the Company’s Shares shall be void unless the
provisions of this Agreement are satisfied. 
 (e) Termination of Rights. The right of first refusal granted the Company by
Section 3(a) above and the option to repurchase the Shares in the event of an involuntary transfer granted the Company by Section 3(b) above shall terminate upon the first sale of Common Stock of the Company to the general public pursuant
to a registration statement filed with and declared effective by the Securities and Exchange Commission under the Securities Act. Upon termination of the right of first refusal described in Section 3(a) above, a new certificate or certificates
representing the Shares not repurchased shall be issued, on request, without the legend referred to in Section 5(a)(ii) herein and delivered to Purchaser. 

5. Investment and Taxation Representations. In connection with the purchase of the Shares, Purchaser represents to the Company
the following: 
 (a) Purchaser 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. Purchaser is purchasing these securities for investment for his or her 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. 
 (b) Purchaser understands that the securities have
not been registered under the Securities Act by reason of a specific exemption therefrom, which exemption depends upon, among other things, the bona fide nature of Purchaser’s investment intent as expressed herein. 

(c) Purchaser understands that the Shares are “restricted securities” under applicable U.S. federal and state securities laws and
that, pursuant to these laws, Purchaser must hold the Shares indefinitely unless they are registered with the Securities and Exchange Commission and qualified by state authorities, or an exemption from such registration and qualification
requirements is available. Purchaser acknowledges that the Company has no obligation to register or qualify the Shares for resale. Purchaser further acknowledges that if an exemption from registration or qualification is available, it may be
conditioned on various requirements including, but not limited to, the time and manner of sale, the holding period for the Shares, and requirements relating to the Company which are outside of the Purchaser’s control, and which the Company is
under no obligation and may not be able to satisfy. 

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

(a) Legends. The certificate or certificates representing the Shares shall bear the following legends (as well as any legends
required by applicable state and federal corporate and securities laws): 
  

	 	(i)	THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “ACT”), AND HAVE BEEN ACQUIRED FOR INVESTMENT AND NOT WITH A VIEW TO, OR IN
CONNECTION WITH, THE SALE OR DISTRIBUTION THEREOF. NO SUCH SALE OR DISPOSITION MAY BE EFFECTED WITHOUT AN EFFECTIVE REGISTRATION STATEMENT RELATED THERETO OR AN OPINION OF COUNSEL IN A FORM SATISFACTORY TO FOR THE COMPANY THAT SUCH REGISTRATION IS
NOT REQUIRED UNDER THE ACT. 

  

	 	(ii)	THE SHARES REPRESENTED BY THIS CERTIFICATE MAY BE TRANSFERRED ONLY IN ACCORDANCE WITH THE TERMS OF AN AGREEMENT BETWEEN THE COMPANY AND THE STOCKHOLDER, A COPY OF WHICH IS ON FILE WITH THE SECRETARY OF THE COMPANY.

 (b) Stop-Transfer Notices. Purchaser 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 Agreement, 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. 
 7. No Employment Rights. Nothing in this Agreement shall affect in any manner whatsoever the right or power of
the Company, or a parent or subsidiary of the Company, to terminate Purchaser’s employment, for any reason, with or without cause. 
 8.
Market Stand-off Agreement. In connection with the initial public offering of the Company’s securities and upon request of the Company or the underwriters managing any underwritten offering of the Company’s securities,
Purchaser agrees not to sell, make any short sale of, loan, grant any option for the purchase of, or otherwise dispose of any Shares (other than those included in the registration) without the prior written consent of the Company or such
underwriters, as the case may be, for such period of time (not to exceed one hundred eighty (180) days) from the effective date of such registration as may be requested by the Company or such managing underwriters and to execute an agreement
reflecting the foregoing as may be requested by the underwriters at the time of the public offering. 

 9. Miscellaneous. 

(a) Governing Law. This Agreement and all acts and transactions pursuant hereto and the rights and obligations of the parties
hereto shall be governed, construed and interpreted in accordance with the laws of the State of Delaware, without giving effect to principles of conflicts of law. 

(b) Entire Agreement; Enforcement of Rights. This Agreement sets forth the entire agreement and understanding of the parties
relating to the subject matter herein and merges all prior discussions between them. No modification of or amendment to this Agreement, nor any waiver of any rights under this Agreement, shall be effective unless in writing signed by the parties to
this Agreement. The failure by either party to enforce any rights under this Agreement shall not be construed as a waiver of any rights of such party. 

(c) Severability. If one (1) or more provisions of this Agreement are held to be unenforceable under applicable law, the
parties agree to renegotiate such provision in good faith. In the event that the parties cannot reach a mutually agreeable and enforceable replacement for such provision, then (i) such provision shall be excluded from this Agreement,
(ii) the balance of the Agreement shall be interpreted as if such provision were so excluded and (iii) the balance of the Agreement shall be enforceable in accordance with its terms. 

(d) Construction. This Agreement is the result of negotiations between and has been reviewed by each of the parties hereto and
their respective counsel, if any; accordingly, this Agreement shall be deemed to be the product of all of the parties hereto, and no ambiguity shall be construed in favor of or against any one of the parties hereto. 

(e) Notices. Any notice required or permitted by this Agreement shall be in writing and shall be deemed sufficient when delivered
personally or sent by telegram or fax or forty-eight (48) hours after being deposited in the U.S. mail, as certified or registered mail, with postage prepaid, and addressed to the party to be notified at such party’s address as set forth
below or as subsequently modified by written notice. 
 (f) Counterparts. This Agreement may be executed in two (2) or
more counterparts, each of which shall be deemed an original and all of which together shall constitute one (1) instrument. 
 (g)
Successors and Assigns. The rights and benefits of this Agreement shall inure to the benefit of, and be enforceable by the Company’s successors and assigns. The rights and obligations of Purchaser under this Agreement may only be
assigned with the prior written consent of the Company. 
 (h) Other Agreements. Purchaser covenants and agrees to sign and
become a party to the Company’s then-current form of Voting Agreement, Stockholder’s Agreement, and any similar agreements to the extent applicable, as requested by the Company. 

 The parties have executed this Exercise Notice and Restricted Stock Purchase Agreement as of the
date first set forth above. 
  

			
	COMPANY:
	
	 ALPINE IMMUNE SCIENCES, INC.,

a Delaware corporation

		
	By:	 	  

	Name:	 	  

	Its:	 	  

		
	Address:	 	                                      
                                      
		 	                                      
                                      
	
	PURCHASER:
	
	NAME:
	
	  

	(Signature)
	
	  

	(Print Name)
	
	Address:                                   
                                     
	                                    
                                         
         

 I,             , spouse of Purchaser, have read and hereby
approve the foregoing Agreement. In consideration of the Company’s granting my spouse the right to purchase the Shares as set forth in the Agreement, I hereby agree to be irrevocably bound by the Agreement and further agree that any community
property or other such interest shall hereby by similarly bound by the Agreement. I hereby appoint my spouse as my attorney-in-fact with respect to any amendment or exercise of any rights under the Agreement. 

 

	
	  
 Spouse of Purchaser

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