EX-4.3





 Exhibit 4.3 

RIGHT OF FIRST REFUSAL 

AND CO-SALE AGREEMENT 

THIS RIGHT OF FIRST REFUSAL AND CO-SALE AGREEMENT (this “Agreement”) is made as of
the 13th day of July, 2020 by and among BioAtla, Inc., a Delaware corporation (the “Company”), the Investors listed on Schedule A and the Key Holders
listed on Schedule B. 
 RECITALS: 

WHEREAS, each Key Holder is the direct or indirect beneficial owner of the number of shares of Capital Stock, or of options to purchase Common
Stock, set forth opposite the name of such Key Holder on Schedule B. 
 WHEREAS, the Company and the Investors are parties to that
certain Series D Preferred Stock Purchase Agreement, of even date herewith (the “Purchase Agreement”), pursuant to which the Investors have agreed to purchase shares of the Series D Preferred Stock of the Company, par value $0.0001
per share (“Series D Preferred Stock”); and 
 WHEREAS, the Key Holders and the Company desire to further induce the
Investors to purchase Series D Preferred Stock; 
 NOW, THEREFORE, the Company, the Key Holders and the Investors agree as follows: 

1. Definitions. 
 1.1.
“Affiliate” means, with respect to any specified Investor, any other Person who, directly or indirectly, controls, is controlled by, or is under common control with, such Investor, including, without limitation, any general partner,
managing member, officer, director or trustee of such Investor, or any limited liability company, limited partnership, investment fund or registered investment company now or hereafter existing that is controlled by one or more general partners,
managers, managing members or investment advisors of, or shares the same management company or investment advisor with, such Investor; any wholly-owned subsidiary of such Investor; or any direct or indirect wholly-owned subsidiary of the ultimate
parent entity of such Investor; provided, however, that (i) each Janus Investor shall be deemed to be an “Affiliate” of each other Janus Investor, and (ii) an entity that is an “Affiliate” of a
Janus Investor shall not be deemed to be an “Affiliate” of any other Janus Investor unless such entity is a Janus Investor (and, for the avoidance of doubt, an “Affiliate” of such entity shall not be deemed an
“Affiliate” of any Janus Investor solely by virtue of being an “Affiliate” of such entity). 
 1.2. “Capital
Stock” means (a) shares of Common Stock and Preferred Stock (whether now outstanding or hereafter issued in any context), (b) shares of Common Stock issued or issuable upon conversion of Preferred Stock and (c) shares of Common
Stock issued or issuable upon exercise or conversion, as applicable, of stock options, warrants or other convertible securities of the Company, in each case now owned or subsequently acquired by any Key Holder, any Investor, or their respective
successors or permitted transferees or assigns. For purposes of the number of shares of Capital Stock held by an Investor or Key Holder (or any other calculation based thereon), all shares of Preferred Stock shall be deemed to have been converted
into Common Stock at the then-applicable conversion ratio. 

  
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 1.3. “Certificate of Incorporation” means the Company’s Certificate of
Incorporation, as amended from time to time. 
 1.4. “Change of Control” means a transaction or series of related
transactions in which a person, or a group of related persons, acquires from stockholders of the Company shares representing more than fifty percent (50%) of the outstanding voting power of the Company. 

1.5. “Common Stock” means shares of Common Stock of the Company, $0.0001 par value per share. 

1.6. “Company Notice” means written notice from the Company notifying the selling Key Holders that the Company intends to
exercise its Right of First Refusal as to all or a portion of the Transfer Stock with respect to any Proposed Key Holder Transfer. 
 1.7.
“Investor Notice” means written notice from an Investor notifying the Company and the selling Key Holder that such Investor intends to exercise its Secondary Refusal Right as to a portion of the Transfer Stock with respect to any
Proposed Key Holder Transfer. 
 1.8. “Investors” means the persons named on Schedule A hereto,
each person to whom the rights of an Investor are assigned pursuant to Subsection 6.10, each person who hereafter becomes a signatory to this Agreement pursuant to Subsection 6.12 and any one of them, as the context may require. 

1.9. “Janus Investors” shall mean Investors, or permitted transferees of Common Stock (issued or issuable upon conversion of
Preferred Stock) held by Janus Investors, that are advisory or subadvisory clients of Janus Capital Management LLC, including, but not limited to, Janus Henderson Global Life Sciences Fund, Janus Henderson Capital Funds Plc—Janus Henderson
Global Life Sciences Fund, and Janus Henderson Biotech Innovation Master Fund Limited. 
 1.10. “Key Holders” means the
persons named on Schedule B hereto, each person to whom the rights of a Key Holder are assigned pursuant to Subsection 3.1, each person who hereafter becomes a signatory to this Agreement pursuant to Subsection
6.10 or 6.18 and any one of them, as the context may require. 
 1.11. “Preferred Stock” means, collectively,
all shares of Series D Preferred Stock. 
 1.12. “Proposed Key Holder Transfer” means any assignment, sale, offer to sell,
pledge, mortgage, hypothecation, encumbrance, disposition of or any other like transfer or encumbering of any Transfer Stock (or any interest therein) proposed by any of the Key Holders. 

1.13. “Proposed Transfer Notice” means written notice from a Key Holder setting forth the terms and conditions of a Proposed
Key Holder Transfer. 

  
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 1.14. “Prospective Transferee” means any person to whom a Key Holder
proposes to make a Proposed Key Holder Transfer. 
 1.15. “Right of Co-Sale” means
the right, but not an obligation, of an Investor to participate in a Proposed Key Holder Transfer on the terms and conditions specified in the Proposed Transfer Notice. 

1.16. “Right of First Refusal” means the right, but not an obligation, of the Company, or its permitted transferees or
assigns, to purchase some or all of the Transfer Stock with respect to a Proposed Key Holder Transfer, on the terms and conditions specified in the Proposed Transfer Notice. 

1.17. “Secondary Notice” means written notice from the Company notifying the Investors and the selling Key Holder that the
Company does not intend to exercise its Right of First Refusal as to all shares of Transfer Stock with respect to any Proposed Key Holder Transfer. 

1.18. “Secondary Refusal Right” means the right, but not an obligation, of each Investor to purchase up to its pro rata
portion (based upon the total number of shares of Capital Stock then held by all Investors) of any Transfer Stock not purchased pursuant to the Right of First Refusal, on the terms and conditions specified in the Proposed Transfer Notice. 

1.19. “Transfer Stock” means shares of Capital Stock directly or indirectly owned by a Key Holder, or issued to a Key Holder
after the date hereof (including, without limitation, in connection with any stock split, stock dividend, recapitalization, reorganization, or the like), but does not include any shares of Preferred Stock or of Common Stock that are issued or
issuable upon conversion of Preferred Stock. 
 1.20. “Undersubscription Notice” means written notice from an Investor
notifying the Company and the selling Key Holder that such Investor intends to exercise its option to purchase all or any portion of the Transfer Stock not purchased pursuant to the Right of First Refusal or the Secondary Refusal Right. 

2. Agreement Among the Company, the Investors and the Key Holders. 

2.1. Right of First Refusal. 

(a) Grant. Subject to the terms of Section 3 below, each Key Holder hereby unconditionally and irrevocably
grants to the Company a Right of First Refusal to purchase all or any portion of Transfer Stock that such Key Holder may propose to transfer in a Proposed Key Holder Transfer, at the same price and on the same terms and conditions as those offered
to the Prospective Transferee. 
 (b) Notice. Each Key Holder proposing to make a Proposed Key Holder Transfer must deliver a
Proposed Transfer Notice to the Company and each Investor not later than forty-five (45) days prior to the consummation of such Proposed Key Holder Transfer. Such Proposed Transfer Notice shall contain the material terms and conditions
(including price and form of consideration) of the Proposed Key Holder Transfer, the identity of the Prospective Transferee and the intended date of the Proposed Key Holder Transfer. To exercise its Right of First Refusal


  
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under this Section 2, the Company must deliver a Company Notice to the selling Key Holder within fifteen (15) days after delivery of the Proposed Transfer Notice
specifying the number of shares of Transfer Stock to be purchased by the Company. In the event of a conflict between this Agreement and any other agreement that may have been entered into by a Key Holder with the Company that contains a preexisting
right of first refusal, the Company and the Key Holder acknowledge and agree that the terms of this Agreement shall control and the preexisting right of first refusal shall be deemed satisfied by compliance with Subsection 2.1(a) and this
Subsection 2.1(b). 
 (c) Grant of Secondary Refusal Right to Investors. Subject to the terms of
Section 3 below, each Key Holder hereby unconditionally and irrevocably grants to the Investors a Secondary Refusal Right to purchase all or any portion of the Transfer Stock not purchased by the Company pursuant to the
Right of First Refusal, as provided in this Subsection 2.1(c). If the Company does not intend to exercise its Right of First Refusal with respect to all Transfer Stock subject to a Proposed Key Holder Transfer, the Company
must deliver a Secondary Notice to the selling Key Holder and to each Investor to that effect no later than fifteen (15) days after the selling Key Holder delivers the Proposed Transfer Notice to the Company. To exercise its Secondary Refusal
Right, an Investor must deliver an Investor Notice to the selling Key Holder and the Company within ten (10) days after the Company’s deadline for its delivery of the Secondary Notice as provided in the preceding sentence. 

(d) Undersubscription of Transfer Stock. If options to purchase have been exercised by the Company and the Investors with respect to
some but not all of the Transfer Stock by the end of the ten (10) day period specified in the last sentence of Subsection 2.1(c) (the “Investor Notice Period”), then the Company shall, immediately after the expiration of
the Investor Notice Period, send written notice (the “Company Undersubscription Notice”) to those Investors who fully exercised their Secondary Refusal Right within the Investor Notice Period (the “Exercising
Investors”). Each Exercising Investor shall, subject to the provisions of this Subsection 2.1(d), have an additional option to purchase all or any part of the balance of any such remaining unsubscribed shares of Transfer Stock on the
terms and conditions set forth in the Proposed Transfer Notice. To exercise such option, an Exercising Investor must deliver an Undersubscription Notice to the selling Key Holder and the Company within ten (10) days after the expiration of the
Investor Notice Period. In the event there are two (2) or more such Exercising Investors that choose to exercise the last-mentioned option for a total number of remaining shares in excess of the number available, the remaining shares available
for purchase under this Subsection 2.1(d) shall be allocated to such Exercising Investors pro rata based on the number of shares of Transfer Stock such Exercising Investors have elected to purchase pursuant to the Secondary Refusal Right
(without giving effect to any shares of Transfer Stock that any such Exercising Investor has elected to purchase pursuant to the Company Undersubscription Notice). If the options to purchase the remaining shares are exercised in full by the
Exercising Investors, the Company shall immediately notify all of the Exercising Investors and the selling Key Holder of that fact. 
 (e)
Consideration; Closing. If the consideration proposed to be paid for the Transfer Stock is in property, services or other non-cash consideration, the fair market value of the consideration shall be as
determined in good faith by the Company’s Board of Directors (the “Board”) and as set forth in the Company Notice. If the Company or any Investor cannot for any 

  
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reason pay for the Transfer Stock in the same form of non-cash consideration, the Company or such Investor may pay the cash value equivalent thereof, as
determined in good faith by the Board and as set forth in the Company Notice. The closing of the purchase of Transfer Stock by the Company and the Investors shall take place, and all payments from the Company and the Investors shall have been
delivered to the selling Key Holder, by the later of (i) the date specified in the Proposed Transfer Notice as the intended date of the Proposed Key Holder Transfer and (ii) forty-five (45) days after delivery of the Proposed Transfer
Notice. 
 2.2. Right of Co-Sale. 

(a) Exercise of Right. If any Transfer Stock subject to a Proposed Key Holder Transfer is not purchased pursuant to Subsection
2.1 above and thereafter is to be sold to a Prospective Transferee, each respective Investor may elect to exercise its Right of Co-Sale and participate on a pro rata basis in the Proposed Key Holder
Transfer as set forth in Subsection 2.2(b) below and, subject to Subsection 2.2(d), otherwise on the same terms and conditions specified in the Proposed Transfer Notice. Each Investor who desires to exercise its Right of Co-Sale (each, a “Participating Investor”) must give the selling Key Holder written notice to that effect within fifteen (15) days after the deadline for delivery of the Secondary Notice
described above, and upon giving such notice such Participating Investor shall be deemed to have effectively exercised the Right of Co-Sale. 

(b) Shares Includable. Each Participating Investor may include in the Proposed Key Holder Transfer all or any part of such
Participating Investor’s Capital Stock equal to the product obtained by multiplying (i) the aggregate number of shares of Transfer Stock subject to the Proposed Key Holder Transfer (excluding shares purchased by the Company or the
Participating Investors pursuant to the Right of First Refusal or the Secondary Refusal Right) by (ii) a fraction, the numerator of which is the number of shares of Capital Stock owned by such Participating Investor immediately before
consummation of the Proposed Key Holder Transfer (including any shares that such Participating Investor has agreed to purchase pursuant to the Secondary Refusal Right) and the denominator of which is the total number of shares of Capital Stock
owned, in the aggregate, by all Participating Investors immediately prior to the consummation of the Proposed Key Holder Transfer (including any shares that all Participating Investors have collectively agreed to purchase pursuant to the Secondary
Refusal Right), plus the number of shares of Transfer Stock held by the selling Key Holder. To the extent one (1) or more of the Participating Investors exercise such right of participation in accordance with the terms and conditions set forth
herein, the number of shares of Transfer Stock that the selling Key Holder may sell in the Proposed Key Holder Transfer shall be correspondingly reduced. 

(c) Purchase and Sale Agreement. The Participating Investors and the selling Key Holder agree that the terms and conditions of any
Proposed Key Holder Transfer in accordance with this Subsection 2.2 will be memorialized in, and governed by, a written purchase and sale agreement with the Prospective Transferee (the “Purchase and Sale Agreement”) with
customary terms and provisions for such a transaction, and the Participating Investors and the selling Key Holder further covenant and agree to enter into such Purchase and Sale Agreement as a condition precedent to any sale or other transfer in
accordance with this Subsection 2.2. 

  
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 (d) Allocation of Consideration. 

(i) Subject to Subsection 2.2(d)(ii), the aggregate consideration payable to the Participating Investors and the selling Key Holder
shall be allocated based on the number of shares of Capital Stock sold to the Prospective Transferee by each Participating Investor and the selling Key Holder as provided in Subsection 2.2(b), provided, that if a Participating Investor
wishes to sell Preferred Stock, the price set forth in the Proposed Transfer Notice shall be appropriately adjusted based on the conversion ratio of the Preferred Stock into Common Stock. 

(ii) In the event that the Proposed Key Holder Transfer constitutes a Change of Control, the terms of the Purchase and Sale Agreement shall
provide that the aggregate consideration from such transfer shall be allocated to the Participating Investors and the selling Key Holder in accordance with Sections 2.1 and 2.2 of Article IV(B) of the Certificate of Incorporation and, if applicable,
the next sentence of this Subsection 2.2(d)(ii) as if (A) such transfer were a Deemed Liquidation Event (as defined in the Certificate of Incorporation), and (B) the Capital Stock sold in accordance with the Purchase and Sale
Agreement were the only Capital Stock outstanding. In the event that a portion of the aggregate consideration payable to the Participating Investor(s) and selling Key Holder is placed into escrow and/or is payable only upon satisfaction of
contingencies, the Purchase and Sale Agreement shall provide that (x) the portion of such consideration that is not placed in escrow and is not subject to contingencies (the “Initial Consideration”) shall be allocated in
accordance with Sections 2.1 and 2.2 of Article IV(B) of the Certificate of Incorporation as if the Initial Consideration were the only consideration payable in connection with such transfer, and (y) any additional consideration which becomes
payable to the Participating Investor(s) and selling Key Holder upon release from escrow or satisfaction of such contingencies shall be allocated in accordance with Sections 2.1 and 2.2 of Article IV(B) of the Certificate of Incorporation after
taking into account the previous payment of the Initial Consideration as part of the same transfer. 
 (e) Purchase by Selling Key
Holder; Deliveries. Notwithstanding Subsection 2.2(c) above, if any Prospective Transferee or Transferees refuse(s) to purchase securities subject to the Right of Co-Sale from any Participating
Investor or Investors or upon the failure to negotiate in good faith a Purchase and Sale Agreement reasonably satisfactory to the Participating Investors, no Key Holder may sell any Transfer Stock to such Prospective Transferee or Transferees unless
and until, simultaneously with such sale, such Key Holder purchases all securities subject to the Right of Co-Sale from such Participating Investor or Investors on the same terms and conditions (including the
proposed purchase price) as set forth in the Proposed Transfer Notice and as provided in Subsection 2.2(d)(i); provided, however, if such sale constitutes a Change of Control, the portion of the aggregate consideration paid by the selling Key
Holder to such Participating Investor or Investors shall be made in accordance with the first sentence of Subsection 2.2(d)(ii). In connection with such purchase by the selling Key Holder, such Participating Investor or Investors shall
deliver to the selling Key Holder any stock certificate or certificates, properly endorsed for transfer, representing the Capital Stock being purchased by the selling Key Holder (or request that the Company effect such transfer in the name of the
selling Key Holder). Any such shares transferred to the selling Key Holder will be transferred to the Prospective Transferee against payment therefor in consummation of the sale of the Transfer Stock pursuant to the terms and conditions specified in
the Proposed Transfer Notice, and the selling Key Holder shall concurrently therewith remit or direct payment to each such Participating Investor the portion of the aggregate consideration to which each such Participating Investor is entitled by
reason of its participation in such sale as provided in this Subsection 2.2(e). 

  
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 (f) Additional Compliance. If any Proposed Key Holder Transfer is not consummated
within forty-five (45) days after receipt of the Proposed Transfer Notice by the Company, the Key Holders proposing the Proposed Key Holder Transfer may not sell any Transfer Stock unless they first comply in full with each provision of this
Section 2. The exercise or election not to exercise any right by any Investor hereunder shall not adversely affect its right to participate in any other sales of Transfer Stock subject to this
Subsection 2.2. 
 2.3. Effect of Failure to Comply. 

(a) Transfer Void; Equitable Relief. Any Proposed Key Holder Transfer not made in compliance with the requirements of this Agreement
shall be null and void ab initio, shall not be recorded on the books of the Company or its transfer agent and shall not be recognized by the Company. Each party hereto acknowledges and agrees that any breach of this Agreement would result in
substantial harm to the other parties hereto for which monetary damages alone could not adequately compensate. Therefore, the parties hereto unconditionally and irrevocably agree that any non-breaching party
hereto shall be entitled to seek protective orders, injunctive relief and other remedies available at law or in equity (including, without limitation, seeking specific performance or the rescission of purchases, sales and other transfers of Transfer
Stock not made in strict compliance with this Agreement). 
 (b) Violation of First Refusal Right. If any Key Holder becomes
obligated to sell any Transfer Stock to the Company or any Investor under this Agreement and fails to deliver such Transfer Stock in accordance with the terms of this Agreement, the Company and/or such Investor may, at its option, in addition to all
other remedies it may have, send to such Key Holder the purchase price for such Transfer Stock as is herein specified and transfer to the name of the Company or such Investor (or request that the Company effect such transfer in the name of an
Investor) on the Company’s books any certificate or certificates, instruments, or book entry representing the Transfer Stock to be sold. 

(c) Violation of Co-Sale Right. If any Key Holder purports to sell any Transfer Stock in
contravention of the Right of Co-Sale (a “Prohibited Transfer”), each Participating Investor who desires to exercise its Right of Co-Sale under
Subsection 2.2 may, in addition to such remedies as may be available by law, in equity or hereunder, require such Key Holder to purchase from such Participating Investor the type and number of shares of Capital Stock that such Participating
Investor would have been entitled to sell to the Prospective Transferee had the Prohibited Transfer been effected in compliance with the terms of Subsection 2.2. The sale will be made on the same terms, including, without limitation, as
provided in Subsection 2.2(d)(i) and the first sentence of Subsection 2.2(d)(ii), as applicable, and subject to the same conditions as would have applied had the Key Holder not made the Prohibited Transfer, except that the sale
(including, without limitation, the delivery of the purchase price) must be made within ninety (90) days after the Participating Investor learns of the Prohibited Transfer, as opposed to the timeframe proscribed in
Subsection 2.2. Such Key Holder shall also reimburse each Participating Investor for any and all reasonable and documented out-of-pocket fees
and expenses, including reasonable legal fees and expenses, incurred pursuant to the exercise or the attempted exercise of the Participating Investor’s rights under Subsection 2.2. 

  
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 3. Exempt Transfers. 

3.1. Exempted Transfers. Notwithstanding the foregoing or anything to the contrary herein, the provisions of Subsections 2.1 and
2.2 shall not apply: (a) in the case of a Key Holder that is an entity, upon a transfer for no consideration by such Key Holder to its stockholders, members, partners or other equity holders, (b) to a repurchase of Transfer Stock
from a Key Holder by the Company at a price no greater than that originally paid by such Key Holder for such Transfer Stock and pursuant to an agreement containing vesting and/or repurchase provisions approved by a majority of the Board, or
(c) in the case of a Key Holder that is a natural person, upon a transfer of Transfer Stock by such Key Holder made for bona fide estate planning purposes, either during his or her lifetime or on death by will or intestacy to his or her spouse,
child (natural or adopted), or any other direct lineal descendant of such Key Holder (or his or her spouse) (all of the foregoing collectively referred to as “family members”), or any other relative approved by unanimous consent of
the Board, or any custodian or trustee of any trust, partnership or limited liability company for the benefit of, or the ownership interests of which are owned wholly by, such Key Holder or any such family members; provided, that in the case
of clause(s) (a) and (c), the Key Holder shall deliver prior written notice to the Investors of such gift or transfer and such shares of Transfer Stock shall at all times remain subject to the terms and restrictions set forth in this Agreement
and such transferee shall, as a condition to such issuance, deliver a counterpart signature page to this Agreement as confirmation that such transferee shall be bound by all the terms and conditions of this Agreement as a Key Holder (but only with
respect to the securities so transferred to the transferee), including the obligations of a Key Holder with respect to Proposed Key Holder Transfers of such Transfer Stock pursuant to Section 2; and provided,
further, in the case of any transfer pursuant to clause (a) or (c) above, that such transfer is made pursuant to a transaction in which there is no consideration actually paid for such transfer. 

3.2. Exempted Offerings. Notwithstanding the foregoing or anything to the contrary herein, the provisions of
Section 2 shall not apply to the sale of any Transfer Stock (a) to the public in an offering pursuant to an effective registration statement under the Securities Act of 1933, as amended (a “Public
Offering”) or (b) pursuant to a Deemed Liquidation Event (as defined in the Certificate of Incorporation). 
 3.3.
Prohibited Transferees. Notwithstanding the foregoing, no Key Holder shall transfer any Transfer Stock to (a) any entity which, in the determination of the Board, directly or indirectly competes with the Company or (b) any customer,
distributor or supplier of the Company, if the Board should determine that such transfer would result in such customer, distributor or supplier receiving information that would place the Company at a competitive disadvantage with respect to such
customer, distributor or supplier. 
 4. Legend. Each certificate, instrument, or book entry representing shares of Transfer Stock
held by the Key Holders or issued to any permitted transferee in connection with a transfer permitted by Subsection 3.1 hereof shall be endorsed with the following legend: 

THE SALE, PLEDGE, HYPOTHECATION OR TRANSFER OF THE SECURITIES REPRESENTED HEREBY IS SUBJECT TO, AND IN CERTAIN CASES PROHIBITED BY, THE TERMS
AND CONDITIONS OF A CERTAIN 

  
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RIGHT OF FIRST REFUSAL AND CO-SALE AGREEMENT BY AND AMONG THE STOCKHOLDER, THE CORPORATION AND CERTAIN OTHER HOLDERS OF STOCK OF THE CORPORATION. COPIES OF
SUCH AGREEMENT MAY BE OBTAINED UPON WRITTEN REQUEST TO THE SECRETARY OF THE CORPORATION. 
 Each Key Holder agrees that the Company may instruct its
transfer agent to impose transfer restrictions on the shares notated with the legend referred to in this Section 4 above to enforce the provisions of this Agreement, and the Company agrees to promptly do so. The legend
shall be removed upon termination of this Agreement at the request of the holder. 
 5.
Lock-Up. 
 5.1. Agreement to Lock-Up. Each Key
Holder hereby agrees that it will not, without the prior written consent of the managing underwriter, during the period commencing on the date of the final prospectus relating to the Company’s initial public offering (the
“IPO”) and ending on the date specified by the Company and the managing underwriter, such period not to exceed one hundred eighty (180) days, or such other period, not to exceed an additional thirty-five (35) days, as may
be requested by the Company or an underwriter to accommodate regulatory restrictions on (1) the publication or other distribution of research reports and (2) analyst recommendations and opinions, including, but not limited to, the
restrictions contained in FINRA Rule 2711(f)(4) or NYSE Rule 472(f)(4), or any successor provisions or amendments thereto, (a) lend, 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, or otherwise transfer or dispose of, directly or indirectly, any shares of Capital Stock held immediately prior to the effectiveness of the registration statement for the IPO; or
(b) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of the Capital Stock, whether any such transaction described in clause (a) or (b) above is to
be settled by delivery of Capital Stock or other securities, in cash or otherwise. The foregoing provisions of this Section 5 shall not apply to the sale of any shares to an underwriter pursuant to an underwriting
agreement, and shall only be applicable to the Key Holders if all officers, directors and holders of more than one percent (1%) of the outstanding Common Stock (after giving effect to the conversion into Common Stock of all outstanding Series D
Preferred Stock) enter into similar agreements. The underwriters in connection with the IPO are intended third-party beneficiaries of this Section 5 and shall have the right, power and authority to enforce the provisions
hereof as though they were a party hereto. Each Key Holder further agrees to execute such agreements as may be reasonably requested by the underwriters in the IPO that are consistent with this Section 5 or that are
necessary to give further effect thereto. 
 5.2. Stop Transfer Instructions. In order to enforce the foregoing covenant, the Company
may impose stop-transfer instructions with respect to the shares of Capital Stock of each Key Holder (and transferees and assignees thereof) until the end of such restricted period. 

6. Miscellaneous. 
 6.1.
Term. This Agreement shall automatically terminate upon the earlier of (a) immediately prior to the consummation of the Company’s IPO and (b) the consummation of a Deemed Liquidation Event (as defined in the Certificate of
Incorporation). 

  
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 6.2. Stock Split. All references to numbers of shares in this Agreement shall be
appropriately adjusted to reflect any stock dividend, split, combination or other recapitalization affecting the Capital Stock occurring after the date of this Agreement. 

6.3. Ownership. Each Key Holder represents and warrants that such Key Holder is the direct or indirect beneficial owner of the shares
of Transfer Stock subject to this Agreement and that no other person or entity has any interest in such shares (other than a community property interest as to which the holder thereof has acknowledged and agreed in writing to the restrictions and
obligations hereunder or, in the case of Himalaya Parent LLC, a Delaware limited liability company, as contemplated by its applicable operating agreement). 

6.4. Dispute Resolution. The parties (a) hereby irrevocably and unconditionally submit to the jurisdiction of the state courts of
Delaware and to the jurisdiction of the United States District Court for the District of Delaware for the purpose of any suit, action or other proceeding arising out of or based upon this Agreement, (b) agree not to commence any suit, action or
other proceeding arising out of or based upon this Agreement except in the state courts of Delaware or the United States District Court for the District of Delaware, and (c) hereby waive, and agree not to assert, by way of motion, as a defense,
or otherwise, in any such suit, action or proceeding, any claim that it is not subject personally to the jurisdiction of the above-named courts, that its property is exempt or immune from attachment or execution, that the suit, action or proceeding
is brought in an inconvenient forum, that the venue of the suit, action or proceeding is improper or that this Agreement or the subject matter hereof may not be enforced in or by such court. 

6.5. WAIVER OF JURY TRIAL: EACH PARTY HEREBY WAIVES ITS RIGHTS TO A JURY TRIAL OF ANY CLAIM OR CAUSE OF ACTION BASED UPON OR ARISING
OUT OF THIS AGREEMENT, THE OTHER TRANSACTION DOCUMENTS, THE SECURITIES OR THE SUBJECT MATTER HEREOF OR THEREOF. THE SCOPE OF THIS WAIVER IS INTENDED TO BE ALL-ENCOMPASSING OF ANY AND ALL DISPUTES THAT MAY BE
FILED IN ANY COURT AND THAT RELATE TO THE SUBJECT MATTER OF THIS TRANSACTION, INCLUDING, WITHOUT LIMITATION, CONTRACT CLAIMS, TORT CLAIMS (INCLUDING NEGLIGENCE), BREACH OF DUTY CLAIMS, AND ALL OTHER COMMON LAW AND STATUTORY CLAIMS. THIS SECTION HAS
BEEN FULLY DISCUSSED BY EACH OF THE PARTIES HERETO AND THESE PROVISIONS WILL NOT BE SUBJECT TO ANY EXCEPTIONS. EACH PARTY HERETO HEREBY FURTHER WARRANTS AND REPRESENTS THAT SUCH PARTY HAS REVIEWED THIS WAIVER WITH ITS LEGAL COUNSEL, AND THAT SUCH
PARTY KNOWINGLY AND VOLUNTARILY WAIVES ITS JURY TRIAL RIGHTS FOLLOWING CONSULTATION WITH LEGAL COUNSEL. 
 6.6. Notices. All notices
and other communications given or made pursuant to this Agreement shall be in writing and shall be deemed effectively given upon the earlier of actual receipt or: (a) personal delivery to the party to be notified, (b) when sent, if sent by
electronic mail or facsimile during normal business hours of the recipient, and if not sent during normal business hours, then on the recipient’s next business day, (c) five (5) days after having been sent by registered or certified mail,
return receipt requested, postage prepaid, or (d) one (1) business day after deposit with a nationally recognized overnight courier, freight prepaid, specifying next business day delivery, with written verification of receipt. All
communications shall be sent to the respective parties at their address as set forth on the signature pages, as the case may be, or to such email address, facsimile number or address as subsequently modified by written notice given in


  
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accordance with this Section 6.6. If notice is given to the Company, it shall be sent to 11085 Torreyana Road, San Diego, CA 92121, Attention: Chief Executive Officer;
and a copy (which shall not constitute notice) shall also be sent to Dechert LLP, 1900 K Street NW, Washington, DC 20006, Attn: David E. Schulman; and if notice is given to the Investors, a copy, which shall not constitute notice, shall also be
given to such counsel as may appear with such Investor’s address on the signature pages attached to the Purchase Agreement. 
 Notwithstanding any of
the foregoing, with respect to HBM Healthcare Investments (Cayman) Ltd., only a nationally recognized courier service (such as FedEx or DHL) shall be used to effectuate the delivery of any notices pursuant to this Subsection 6.6, and such
notice or other communication for purpose of this Agreement shall not be treated as effective or having been given if some other delivery method is utilized; provided, however, that if such notice is being sent internationally, it
shall not be deemed defective if such courier does not deliver such notice on the next business day following deposit (provided that such notice shall be deemed delivered on the date of delivery by such courier service), and provided further, that
HBM may agree to receive notice in some other manner set forth in this Subsection 6.6 by written election; and a copy (which shall not constitute notice) shall also be sent to Sidley Austin LLP, 1999 Avenue of the Stars, 17th Floor, Los
Angeles, California 90067, Attention: Mehdi Khodadad. 
 6.7. Entire Agreement. This Agreement (including the Exhibits and Schedules
hereto) constitutes the full and entire understanding and agreement between the parties with respect to the subject matter hereof, and any other written or oral agreement relating to the subject matter hereof existing between the parties are
expressly canceled. 
 6.8. Delays or Omissions. No delay or omission to exercise any right, power or remedy accruing to any party
under this Agreement, upon any breach or default of any other party under this Agreement, shall impair any such right, power or remedy of such non-breaching or
non-defaulting party nor shall it be construed to be a waiver of any such breach or default, or an acquiescence therein, or of or in any similar breach or default thereafter occurring; nor shall any waiver of
any single breach or default be deemed a waiver of any other breach or default theretofore or thereafter occurring. Any waiver, permit, consent or approval of any kind or character on the part of any party of any breach or default under this
Agreement, or any waiver on the part of any party of any provisions or conditions of this Agreement, must be in writing and shall be effective only to the extent specifically set forth in such writing. All remedies, either under this Agreement or by
law or otherwise afforded to any party, shall be cumulative and not alternative. 
 6.9. Amendment; Modification; Waiver and
Termination. This Agreement may be amended, modified or terminated (other than pursuant to Section 6.1 above) and the observance of any term hereof may be waived (either generally or in a particular instance and either retroactively or
prospectively) only by a written instrument executed by (a) the Company, (b) the Key Holders holding a majority of Transfer Stock then held by all of the Key Holders who are then providing services to the Company as officers,
employees, or consultants, and (c) the Investors holding a majority of the Series D Preferred Stock, voting together as a single class on an as-converted basis. Any amendment, modification, termination or
waiver so effected shall be binding upon the Company, the Investors, the Key Holders and all of their respective successors and permitted assigns whether or not such party, assignee or other shareholder entered into or approved such amendment,
modification, termination or waiver. Notwithstanding the foregoing, 

  
 11 













 
(i) this Agreement may not be amended, modified or terminated and the observance of any term hereunder may not be waived with respect to any Investor or Key Holder without the written consent of
such Investor or Key Holder unless such amendment, modification, termination or waiver applies to all Investors and Key Holders, respectively, in the same fashion, (ii) this Agreement may not be amended, modified or terminated and the
observance of any term hereunder may not be waived with respect to any Investor without the written consent of such Investor, if such amendment, modification, termination or waiver would adversely affect the rights of such Investor in a manner
disproportionate to any adverse effect such amendment, modification, termination or waiver would have on the rights of the other Investors under this Agreement, (iii) the consent of the Key Holders shall not be required for any amendment,
modification, termination or waiver if such amendment, modification, termination or waiver does not apply to the Key Holders, (iv) Schedule A hereto may be amended by the Company from time to time in accordance with the Purchase
Agreement to add information regarding Additional Purchasers (as defined in the Purchase Agreement) without the consent of the other parties hereto, and (v) the definition of “Affiliate” (as it pertains to the Janus Investors), the
definition of “Janus Investors” and this Section 6.9 (as it pertains to the Janus Investors) shall not be amended, modified, terminated or waived without the prior written consent of the Janus Investors. The
Company shall give prompt written notice of any amendment, modification or termination hereof or waiver hereunder to any party hereto that did not consent in writing to such amendment, modification, termination or waiver. No waivers of or exceptions
to any term, condition or provision of this Agreement, in any one or more instances, shall be deemed to be, or construed as, a further or continuing waiver of any such term, condition or provision. 

6.10. Assignment of Rights. 

(a) The terms and conditions of this Agreement, and the rights and obligations of the parties hereunder, shall inure to the benefit of and be
binding upon the respective successors, permitted assigns, heirs, executors and legal representatives of the parties and shall inure to the benefit of and be enforceable by each person who shall be an Investor from time to time, including any
permitted transferee. Nothing in this Agreement, express or implied, is intended to confer upon any party other than the parties hereto or their respective successors and permitted assigns any rights, remedies, obligations, or liabilities under or
by reason of this Agreement, except as expressly provided in this Agreement. The rights of any Investor under this Agreement may be assigned, in whole or in part, to any Affiliate of such Investor in connection with a transfer of such
Investor’s Capital Stock by such Investor to such Affiliate. 
 (b) Any successor or permitted assignee of any Key Holder, including
any Prospective Transferee who purchases shares of Transfer Stock in accordance with the terms hereof, shall deliver to the Company and the Investors, as a condition to any transfer or assignment, a counterpart signature page hereto pursuant to
which such successor or permitted assignee shall confirm their agreement to be subject to and bound by all of the provisions set forth in this Agreement that were applicable to the predecessor or assignor of such successor or permitted assignee.

 (c) The rights of the Investors hereunder are not assignable without the Company’s written consent (which shall not be unreasonably
withheld, delayed or conditioned), except (i) by an Investor to any Affiliate or (ii) to an assignee or transferee who acquires at least ten percent (10%) of the shares of Capital Stock (as adjusted for any stock combination, stock split,
stock dividend, recapitalization or other similar transaction) originally purchased by such Investor, 

  
 12 













 
it being acknowledged and agreed that any such assignment, including an assignment contemplated by the preceding clauses (i) or (ii) shall be subject to and conditioned upon any such
assignee’s delivery to the Company and the other Investors of a counterpart signature page hereto pursuant to which such assignee shall confirm their agreement to be subject to and bound by all of the provisions set forth in this Agreement that
were applicable to the assignor of such assignee. 
 (d) Except in connection with an assignment by the Company by operation of law to the
acquirer of the Company, the rights and obligations of the Company hereunder may not be assigned under any circumstances. 
 6.11.
Severability. The invalidity or unenforceability of any provision hereof shall in no way affect the validity or enforceability of any other provision. 

6.12. Additional Investors. Notwithstanding anything to the contrary contained herein, if the Company issues additional shares of the
Company’s Series D Preferred Stock after the date hereof, any purchaser of such shares of Series D Preferred Stock may become a party to this Agreement by executing and delivering an additional counterpart signature page to this Agreement and
thereafter shall be deemed an “Investor” for all purposes hereunder. 
 6.13. Governing Law. This Agreement and any
controversy arising out of or relating to this Agreement shall be governed by and construed in accordance with the General Corporation Law of the State of Delaware as to matters within the scope thereof, and as to all other matters shall be governed
by and construed in accordance with the internal laws of the State of Delaware, without regard to its principles of conflicts of laws. 

6.14. Titles and Subtitles. The titles and subtitles used in this Agreement are used for convenience only and are not to be considered
in construing or interpreting this Agreement. 
 6.15. Counterparts. This Agreement may be executed in two (2) or more
counterparts, each of which shall be deemed an original, but all of which together shall constitute one and the same instrument. Counterparts may be delivered via facsimile, electronic mail (including pdf or any electronic signature complying with
the U.S. federal ESIGN Act of 2000, e.g., www.docusign.com) or other transmission method and any counterpart so delivered shall be deemed to have been duly and validly delivered and be valid and effective for all purposes. 

6.16. Aggregation of Stock. All shares of Capital Stock held or acquired by Affiliated entities or persons shall be aggregated together
for the purpose of determining the availability of any rights under this Agreement and such Affiliated persons may apportion such rights as among themselves in any manner they deem appropriate. 

6.17. Specific Performance. In addition to any and all other remedies that may be available at law in the event of any breach of this
Agreement, each Investor shall be entitled to specific performance of the agreements and obligations of the Company and the Key Holders hereunder and to such other injunction or other equitable relief as may be granted by a court of competent
jurisdiction. 
 6.18. Additional Key Holders. In the event that after the date of this Agreement, the Company issues shares of
Common Stock, or options to purchase Common Stock, to any employee or consultant, which shares or options would collectively constitute with respect to such employee or consultant (taking into account all shares of Common Stock, options and other
purchase rights held by such employee or consultant) one percent (1%) or more of the Company’s then outstanding Common Stock (treating for this purpose all shares of Common Stock issuable 

  
 13 













 
upon exercise of or conversion of outstanding options, warrants or convertible securities, as if exercised or converted), the Company shall, as a condition to such issuance, cause such employee
or consultant to execute a counterpart signature page hereto as a Key Holder, and such person shall thereby be bound by, and subject to, all the terms and provisions of this Agreement applicable to a Key Holder. 

6.19. Consent of Spouse. If any Key Holder is married on the date of this Agreement, such Key Holder’s spouse shall execute and
deliver to the Company a consent of spouse in the form of Exhibit A hereto (“Consent of Spouse”), effective on the date hereof. Notwithstanding the execution and delivery thereof, such consent shall not be deemed to confer or
convey to the spouse any rights in such Key Holder’s shares of Transfer Stock that do not otherwise exist by operation of law or the agreement of the parties. If any Key Holder should marry or remarry subsequent to the date of this Agreement,
such Key Holder shall within thirty (30) days thereafter obtain his/her new spouse’s acknowledgement of and consent to the existence and binding effect of all restrictions contained in this Agreement by causing such spouse to execute and
deliver a Consent of Spouse acknowledging the restrictions and obligations contained in this Agreement and agreeing and consenting to the same. 

[Remainder of Page Intentionally Left Blank]  

  
 14 













 IN WITNESS WHEREOF, the parties have executed this Right of First Refusal and Co-Sale Agreement as of the date first written above. 
  

			
	BIOATLA, INC.
		
	By:	 	/s/ Jay Short
	Name:	 	Jay Short
	Title:	 	Chief Executive Officer
		
	Address:	 	11805 Torreyana Road
San Diego, CA 92121


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	 KEY HOLDERS:
  

Jay Short, PhD

		
	By:	 	/s/ Jay Short
	Name:	 	Jay Short
	Title:	 	Chief Executive Officer
		
	Address:	 	11805 Torreyana Road
San Diego, CA 92121


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	 KEY HOLDERS:
  

Carolyn Short

		
	By:	 	/s/ Carolyn Short
	Name:	 	Carolyn Short
		
	Address:	 	11805 Torreyana Road
San Diego, CA 92121


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	KEY HOLDERS:
	
	Scott Smith
		
	By:	 	/s/ Scott Smith
	Name:	 	Scott Smith
		
	Address:	 	11805 Torreyana Road
San Diego, CA 92121


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	KEY HOLDERS:
	
	HIMALAYA PARENT LLC
		
	By:	 	/s/ Jay Short
	Name:	 	Jay Short
	Title:	 	Chief Executive Officer
		
	Address:	 	11805 Torreyana Road
San Diego, CA 92121


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	KEY HOLDERS:
	
	 BIOTECH INVESTMENT GROUP, LLC

		
	By:	 	/s/ Masood Tayebi
	Name:	 	Masood Tayebi
	Title:	 	Managing Member
		
	Address:	 	7310 Miramar Road Suite 500
San Diego, CA 92126


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 IN WITNESS WHEREOF, the parties have executed this Right of First Refusal and Co-Sale Agreement as of the date first written above. 
  

			
	INVESTOR:
	
	SOLEUS PRIVATE EQUITY FUND I, L.P.
	By: Soleus Private Equity GP I, LLC, its General Partner
		
	 By:
	 	/s/ Steven Musumeci
	Name:	 	Steven Musumeci
	Title:	 	Chief Operating Officer
		
	Address:	 	Soleus Private Equity Fund I, L.P. 104 Field Point Road, Second Floor Greenwich, CT 06830


 [Signature Page to Right of First Refusal and Co-Sale Agreement] 












 IN WITNESS WHEREOF, the parties have executed this Right of First Refusal and Co-Sale Agreement as of the date first written above. 
  

			
	INVESTOR:
	
	HBM HEALTHCARE INVESTMENTS (CAYMAN) LTD.
		
	By:	 	/s/ Jean-Marc LeSieur
	Name:	 	Jean-Marc LeSieur
	Title:	 	Director
		
	Address:	 	Governors Square, Suite #4-212-2 23 Lime Tree Bay Avenue
West Bay
Grand Cayman, Cayman Islands


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 IN WITNESS WHEREOF, the parties have executed this Right of First Refusal and Co-Sale Agreement as of the date first written above. 
  

			
	INVESTOR:
	
	ZONE II HEALTHCARE HOLDINGS, LLC
	
	By: Farallon Capital Management, L.L.C., its Manager
		
	By:	 	/s/ Philip Dreyfuss
	Name:	 	Philip Dreyfuss
	Title:	 	Managing Member
		
	Address:	 	c/o Farallon Capital Management, L.L.C.
One Maritime Plaza, Suite 2100
San Francisco, CA 94111
Attn: Philip
Dreyfuss
Email:
pdreyfuss@faralloncapital.com
And
Email:
generalcounsel@faralloncapital.com


 [Signature Page to Right of First Refusal and Co-Sale Agreement] 












 IN WITNESS WHEREOF, the parties have executed this Right of First Refusal and Co-Sale Agreement as of the date first written above. 
  

			
	INVESTOR:
	
	CORMORANT GLOBAL HEALTHCARE MASTER FUND, LP
	
	By: Cormorant Global Healthcare GP, LLC
		
	By:	 	/s/ Bihua Chen
	Name:	 	Bihua Chen
	Title:	 	Managing Member of the GP
		
	Address:	 	 200 Clarendon Street, 52nd Floor
Boston, MA 02116



 [Signature Page to Right of First Refusal and Co-Sale Agreement] 












 IN WITNESS WHEREOF, the parties have executed this Right of First Refusal and Co-Sale Agreement as of the date first written above. 
  

			
	INVESTOR:
	
	CORMORANT PRIVATE HEALTHCARE FUND II, LP
	
	By: Cormorant Private Healthcare GP II, LLC
		
	By:	 	/s/ Bihua Chen
	Name:	 	Bihua Chen
	Title:	 	Managing Member of the GP
		
	Address:	 	200 Clarendon Street, 52nd Floor
Boston, MA 02116


 [Signature Page to Right of First Refusal and Co-Sale Agreement] 












 IN WITNESS WHEREOF, the parties have executed this Right of First Refusal and Co-Sale Agreement as of the date first written above. 
  

			
	INVESTOR:
	
	667, L.P.
	
	By: BAKER BROS. ADVISORS LP, management company and investment advisor to 667, L.P., pursuant to authority granted to it by Baker Biotech Capital, L.P., general partner to 667, L.P., and not as the general
partner.
		
	By:	 	/s/ Scott Lessing
	Name:	 	Scott Lessing
	Title:	 	President
		
	Address:	 	860 Washington St, 3rd Floor
New York, NY 10014


 [Signature Page to Right of First Refusal and Co-Sale Agreement] 












 IN WITNESS WHEREOF, the parties have executed this Right of First Refusal and Co-Sale Agreement as of the date first written above. 
  

			
	INVESTOR:
	
	BAKER BROTHERS LIFE SCIENCES,
L.P.
		
	By:	 	BAKER BROS. ADVISORS LP,
management company and investment advisor to Baker Brothers Life Sciences, L.P., pursuant to authority granted to it by Baker Brothers Life Sciences Capital, L.P., general partner to Baker Brothers Life
Sciences, L.P., and not as the general
partner.


  

			
	By:	 	/s/ Scott Lessing
	Name:	 	Scott Lessing
	Title:	 	President
		
	Address:	 	 860 Washington St, 3rd Floor

New York, NY 10014



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 IN WITNESS WHEREOF, the parties have executed this Right of First Refusal and Co-Sale Agreement as of the date first written above. 
  

			
	INVESTOR:
	
	A.M. PAPPAS LIFE SCIENCE VENTURES V, LP
		
	By:	 	AMP&A Management V, LLC, its General Partner


  

			
	By:	 	/s/ Arthur M. Pappas


 
			
	Name:	 	Arthur M. Pappas
	Title:	 	CEO & Managing Partner
		
	Address:	 	c/o Matthew Boyer
		 	 Pappas Capital, LLC
 2520 Meridian Parkway,
Suite 400
 Durham, NC 27713

mboyer@pappas-capital.com
 (919) 998-3300



 [Signature Page to Right of First Refusal and Co-Sale Agreement] 












 IN WITNESS WHEREOF, the parties have executed this Right of First Refusal and Co-Sale Agreement as of the date first written above. 
  

			
	INVESTOR:
	
	PV V CE FUND, LP
		
	By:	 	AMP&A Management V, LLC, its General Partner


  

			
	By:	 	/s/ Arthur M. Pappas


 
			
	Name:	 	Arthur M. Pappas
	Title:	 	CEO & Managing Partner
		
	Address:	 	c/o Matthew Boyer
		 	 Pappas Capital, LLC
 2520 Meridian Parkway,
Suite 400
 Durham, NC 27713

mboyer@pappas-capital.com
 (919) 998-3300



 [Signature Page to Right of First Refusal and Co-Sale Agreement] 












 IN WITNESS WHEREOF, the parties have executed this Right of First Refusal and Co-Sale Agreement as of the date first written above. 
  

			
	INVESTOR:
	
	JANUS HENDERSON GLOBAL LIFE SCIENCES FUND
	
	By: Janus Capital Management LLC, its
investment advisor
		
	By:	 	/s/ Andrew Acker
	Name:	 	Andrew Acker
	Title:	 	Authorized Signatory
		
	Address:	 	 c/o Janus Capital Management LLC
 151 Detroit
Street
 Denver, CO 80206

	
	 With a copy (which shall not constitute notice) to:

Perkins Coie LLP

3150 Porter Drive

Palo Alto, CA 94306

Attn: Adrian Rich

Email: arich@perkinscoie.com



 [Signature Page to Right of First Refusal and Co-Sale Agreement] 












 IN WITNESS WHEREOF, the parties have executed this Right of First Refusal and Co-Sale Agreement as of the date first written above. 
  

			
	INVESTOR:
	
	JANUS HENDERSON BIOTECH INNOVATION MASTER FUND LIMITED FUND
	
	By: Janus Capital Management LLC, its
investment advisor
		
	By:	 	/s/ Andrew Acker
	Name:	 	Andrew Acker
	Title:	 	Authorized Signatory
		
	Address:	 	 c/o Janus Capital Management LLC
 151 Detroit
Street
 Denver, CO 80206

	
	 With a copy (which shall not constitute notice) to:

Perkins Coie LLP

3150 Porter Drive

Palo Alto, CA 94306

Attn: Adrian Rich

Email: arich@perkinscoie.com



 [Signature Page to Right of First Refusal and Co-Sale Agreement] 












 IN WITNESS WHEREOF, the parties have executed this Right of First Refusal and Co-Sale Agreement as of the date first written above. 
  

			
	INVESTOR:
	
	JANUS HENDERSON CAPITAL
FUNDS PLC ON BEHALF OF ITS
SERIES JANUS HENDERSON
GLOBAL LIFE SCIENCES FUND
	
	By: Janus Capital Management LLC, its
investment advisor
		
	By:	 	/s/ Andrew Acker
	Name:	 	Andrew Acker
	Title:	 	Authorized Signatory
		
	Address:	 	 c/o Janus Capital Management LLC
 151 Detroit
Street
 Denver, CO 80206

	
	 With a copy (which shall not constitute notice) to:

Perkins Coie LLP

3150 Porter Drive

Palo Alto, CA 94306

Attn: Adrian Rich

Email: arich@perkinscoie.com



 [Signature Page to Right of First Refusal and Co-Sale Agreement] 












 IN WITNESS WHEREOF, the parties have executed this Right of First Refusal and Co-Sale Agreement as of the date first written above. 
  

			
	 INVESTOR: 

	
	BOXER CAPITAL, LLC
		
	By:	 	/s/ Aaron Davis
	Name:	 	Aaron Davis
	Title:	 	Chief Executive Officer
		
	Address:	 	 11682 El Camino Real, Suite 320
San Diego, CA 92130



 [Signature Page to Right of First Refusal and Co-Sale Agreement] 












 IN WITNESS WHEREOF, the parties have executed this Right of First Refusal and Co-Sale Agreement as of the date first written above. 
  

			
	INVESTOR:
	
	MVA INVESTORS, LLC
		
	By:	 	/s/ Aaron Davis
	Name:	 	Aaron Davis
	Title:	 	Chief Executive Officer
		
	Address:	 	11682 El Camino Real, Suite 320
San Diego, CA 92130


 [Signature Page to Right of First Refusal and Co-Sale Agreement] 












 IN WITNESS WHEREOF, the parties have executed this Right of First Refusal and Co-Sale Agreement as of the date first written above. 
  

			
	INVESTOR:
	
	PFIZER VENTURES (US) LLC
		
	By:	 	/s/ Barbara Dalton, Ph.D.
	Name:	 	Barbara Dalton, Ph. D.
	Title:	 	President, Pfizer Ventures (US) LLC
		
	Address:	 	 Andrew J. Muratore, Esq.
Pfizer Inc.
235 East 42nd Street
New York, NY
10017



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 SCHEDULE A 

INVESTORS 
 Soleus Private Equity Fund I,
L.P. 
 HBM Healthcare Investments (Cayman) Ltd. 
 Zone II
Healthcare Holdings, LLC 
 Cormorant Global Healthcare Master Fund, LP 

Cormorant Private Healthcare Fund II, LP 667, L.P. 
 Baker
Brothers Life Sciences, L.P. 
 A.M. Pappas Life Science Ventures V, LP 

PV V CEO Fund, LP 
 Janus Henderson Global Life Sciences Fund

 Janus Henderson Capital Funds Plc—Janus Henderson Global Life Sciences Fund 

Janus Henderson Biotech Innovation Master Fund Limited Fund 

Boxer Capital, LLC 
 MVA Investors, LLC 

Pfizer Ventures (US) LLC 












 SCHEDULE B 

KEY HOLDERS 
 Jay Short 

Carolyn Short 
 Scott Smith 

Biotech Investment Group, LLC 
 Himalaya Parent LLC