Document:

EX-10.52

 Exhibit 10.52 

EXECUTION VERSION 
 THIRD AMENDED
AND RESTATED VOTING AGREEMENT 
 THIS THIRD AMENDED AND RESTATED VOTING AGREEMENT (this “Agreement”) is made and
entered into as of March 2, 2021, by and among Caribou Biosciences, Inc., a Delaware corporation (the “Company”), PFM Health Sciences, LP, each holder of the Company’s Series A Preferred Stock, $0.0001 par value per share
(“Series A Preferred Stock”), each holder of the Company’s Series A-1 Preferred Stock, $0.0001 par value per share (“Series A-1
Preferred Stock”), each holder of the Company’s Series B Preferred Stock, $0.0001 par value per share (the “Series B Preferred Stock”), each holder of the Company’s Series C Preferred Stock, $0.0001 par value per
share (the “Series C Preferred Stock;” and referred to herein collectively with the Series A Preferred Stock, the Series A-1 Preferred Stock, and the Series B Preferred Stock, the
“Preferred Stock”), listed on Schedule A (together with any subsequent investors, or transferees, who become parties hereto as “Investors” pursuant to Sections 6.1(a) or 6.2 below, the
“Investors”) and those certain stockholders of the Company and holders of options to acquire shares of the capital stock of the Company listed on Schedule B (together with any subsequent stockholders or option holders,
or any transferees, who become parties hereto as “Key Holders” pursuant to Sections 6.1(b) or 6.2 below, the “Key Holders”, and together collectively with the Investors, the “Stockholders”).

 RECITALS 
 A. The
Company, certain of the Investors, and the Key Holders previously entered into a Second Amended and Restated Voting Agreement, dated as of May 12, 2016 (the “Prior Agreement”), in connection with the purchase of shares of
Series B Preferred Stock by certain of the Investors and desire to amend and restate the Prior Agreement as set forth herein. 
 B.
Concurrently with the execution of this Agreement, the Company and certain of the Investors are entering into a Series C Preferred Stock Purchase Agreement (the “Purchase Agreement”) providing for the sale of shares of Series C
Preferred Stock. 
 C. The Fourth Amended and Restated Certificate of Incorporation of the Company (the “Restated
Certificate”) provides that (a) the holders of the Series C Preferred Stock, voting as a separate class, shall be entitled to elect two (2) directors of the Company (the “Series C Preferred Directors”), (b) the
holders of Series A Preferred Stock, Series A-1 Preferred Stock and Series B Preferred Stock, voting together as a single separate class, on an as-converted to Common
Stock basis, shall be entitled to elect one (1) director of the Company (the “Series A/A-1/B Preferred Director” and together with the Series C Preferred Directors then in office,
the “Preferred Directors”, and each of them, a “Preferred Director”), (c) the holders of the shares of Common Stock, voting as a separate class, shall be entitled to elect one (1) director of the Company, and
(d) the holders of the shares of Common Stock and the holders of the shares of Preferred Stock, voting together as a single class on an as-converted to Common Stock basis, shall be entitled to elect the
balance of the total number of directors of the Company. 
 D. The Company desires to induce certain of the Investors to enter into the
Purchase Agreement by amending and restating the Prior Agreement in its entirety as set forth herein, and the parties hereto desire to set forth herein their agreements and understandings with respect to how shares of the Company’s capital
stock held by them will be voted or tendered in connection with, an acquisition of the Company and in connection with an increase in the number of shares of Common Stock required to provide for the conversion of the Preferred Stock. 

NOW, THEREFORE, the parties agree as follows: 

1. Voting Provisions Regarding Board of Directors. 

1.1. Size of the Board. Each Stockholder agrees to vote, or cause to be voted, all Shares (as defined below) owned by such Stockholder,
or over which such Stockholder has voting control, from time to time and at all times, in whatever manner as shall be necessary to ensure that the size of the Board of Directors of the Company (the “Board”) shall be set and remain
at seven (7) directors. For purposes of this Agreement, the term “Shares” shall mean and include any securities of the Company the holders of which are entitled to vote for members of the Board,

  
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including without limitation, all shares of Common Stock, Series A Preferred Stock, Series A-1 Preferred Stock, Series B Preferred Stock, and Series C
Preferred Stock, by whatever name called, now owned or subsequently acquired by a Stockholder, however acquired, whether through stock splits, stock dividends, reclassifications, recapitalizations, similar events or otherwise. 

1.2. Board Composition. Each Stockholder agrees to vote, or cause to be voted, all Shares owned by such Stockholder, or over which such
Stockholder has voting control, from time to time and at all times, in whatever manner as shall be necessary to ensure that at each annual or special meeting of stockholders at which an election of directors is held or pursuant to any written
consent of the stockholders, the following natural persons shall be elected to the Board: 
 (a) One (1) person elected by a majority
in interest of the holders of the Series A Preferred Stock, the Series A-1 Preferred Stock and the Series B Preferred Stock, voting together as a single class on an
as-converted to Common Stock basis (the “Series A/A-1/B Designee”), who shall be designated by F-Prime Capital
Partners Healthcare Fund IV LP (“F-Prime”) for so long as F-Prime and its Affiliates (as defined below) continue to own beneficially at least 1,019,692
of the shares of Common Stock of the Company (including shares of Common Stock issued or issuable upon conversion of the Series A-1 Preferred Stock), which number is subject to appropriate adjustment for all
stock splits, dividends, combinations, recapitalizations and the like. The Series A/A-1/B Designee shall initially be Robert Weisskoff; 

(b) Two (2) persons elected by the holders of a majority of the shares of Series C Preferred Stock outstanding, voting as a single class
(i) one of whom (the “PFM Series C Designee”) shall be designated by PFM Health Sciences, LP and its Affiliate funds (“PFM”) for so long as PFM continues to own beneficially at least 231,790 shares of Series C
Preferred Stock (including shares of Common Stock issued or issuable upon conversion of the Series C Preferred Stock), which number is subject to appropriate adjustment for all stock splits, dividends, combinations, recapitalizations and the like,
and (ii) one of whom (the “Ridgeback Series C Designee;” the Ridgeback Designee and the PFM Designee are collectively referred to herein as the “Series C Designees”) shall be designated by RIDGEBACK CAPITAL
INVESTMENTS LP (“Ridgeback”) for so long as Ridgeback and its Affiliate funds continue to own beneficially at least 231,790 shares of Series C Preferred Stock (including shares of Common Stock issued or issuable upon conversion of
the Series C Preferred Stock), which number is subject to appropriate adjustment for all stock splits, dividends, combinations, recapitalizations and the like; provided, however, that if either PFM and/or Ridgeback is no longer
entitled to designate a Series C Designee as provided in this sentence, then Zone III Healthcare Holdings, LLC (“Farallon”) shall be entitled to designate the Series C Designee that otherwise would have been designated by PFM and/or
Ridgeback (as the case may be) provided that Farallon and its Affiliate funds owns beneficially as of the date Farallon’s right to designate a Series C Designee becomes effective hereunder, and thereafter Farallon and its Affiliate funds
continue to own beneficially, at least 231,790 shares of Series C Preferred Stock (including shares of Common Stock issued or issuable upon conversion of the Series C Preferred Stock), which number is subject to appropriate adjustment for all stock
splits, dividends, combinations, recapitalizations and the like. The PFM Series C Designee shall initially be Santhosh Palani; and the Ridgeback Series C Designee shall initially be Jeffrey Long-McGie; 

(c) One (1) person elected by the holders of a majority of the shares of Common Stock outstanding (the “Common
Designee”), which Common Designee shall be the Company’s Chief Executive Officer, who shall initially be Rachel E. Haurwitz (the “CEO Director”), provided that if for any reason the CEO Director shall cease to serve as
the Chief Executive Officer of the Company, each of the Stockholders shall promptly vote their respective Shares (i) to remove the former Chief Executive Officer from the Board if such person has not resigned as a member of the Board and
(ii) to elect such person’s replacement as Chief Executive Officer of the Company as the new CEO Director; and 
 (d) Three
(3) independent persons with experience in the life sciences field who are not affiliated with the Company or any Investor, which persons shall be elected by the holders of a majority of the shares of Common Stock and the Preferred Stock
outstanding, voting together as a single class on an as-converted to Common Stock basis (the “Independent Directors”), and shall initially be designated by management of the Company and
approved by a majority of the Preferred Directors. The Independent Directors shall initially be Natalie Sacks with two (2) initial vacancies in the seats allocated for Independent Directors. After an Independent Director

  
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shall initially be elected or appointed for a seat, any re-elections, substitutions or replacements for that seat shall be designees proposed by management
of the Company and approved by a majority of the remaining Board members (including the remaining sitting Independent Directors). 
 To the
extent that any of clauses (a) through (d) above shall not be applicable, any member of the Board who would otherwise have been designated in accordance with the terms thereof shall instead be voted upon by all the stockholders of the Company
entitled to vote thereon in accordance with, and pursuant to, the Company’s Restated Certificate. 
 For purposes of this Agreement, an
individual, firm, corporation, partnership, association, limited liability company, trust or any other entity (collectively, a “Person”) shall be deemed an “Affiliate” of another Person who, directly or indirectly,
controls, is controlled by, or is under common control with such Person, including, without limitation, any general partner, limited partner, member, manager, managing member, employee, officer or director of such Person or any venture capital fund
now or hereafter existing that is controlled by one or more general partners or managing members of, or is under common investment management with or shares the same management company with, such Person. For purposes of this definition, the term
“control” when used with respect to any Person shall mean the power to direct the management or policies of such Person, directly or indirectly, whether through ownership of voting securities, by contract or otherwise, and the terms
“controlling” and “controlled” shall have meanings correlative to the foregoing. 
 1.3. Failure to Designate a Board
Member. In the absence of any designation from the Persons or groups with the right to designate a director as specified above, the director previously designated by them and then serving shall be reelected if willing and eligible to serve;
otherwise such Board seat shall remain vacant until otherwise filled as provided above. 
 1.4. Removal of Board Members. Each
Stockholder also agrees to vote, or cause to be voted, all Shares owned by such Stockholder, or over which such Stockholder has voting control, from time to time and at all times, in whatever manner as shall be necessary to ensure that: 

(a) no director elected pursuant to Section 1.2(a), (b) or (d) or
Section 1.3 of this Agreement may be removed from office unless (i) such removal is directed or approved by (A) in the case of Section 1.2(a) or (b), the affirmative vote of the
Person(s) entitled under Section 1.2(a) or (b), as the case may be, to designate such director or (B) in the case of Section 1.2(d), a majority of the other Board members; and
(ii) the Person(s) originally entitled to designate or approve such director or occupy such Board seat pursuant to Section 1.2 (a), (b) or (d) is no longer so entitled to designate or approve such
director or occupy such Board seat; 
 (b) any vacancies created by the resignation, removal or death of a director elected pursuant to
Sections 1.3 or 1.4 shall be filled pursuant to the provisions of this Section 1; and 

(c) upon the request of any party or parties entitled to designate a director as provided in Section 1.2(a) and
Section 1.2(b) and to remove an Independent Director pursuant Section 1.4(a)(i)(B), in each case to remove such director, such director shall be removed. 

All Stockholders agree to execute any written consents required to perform the obligations of this Agreement, and the Company agrees at the request of any
party entitled to designate directors to call a special meeting of stockholders for the purpose of electing directors. 
 1.5. No
Liability for Election of Recommended Directors. No Stockholder, nor any Affiliate of any Stockholder, shall have any liability as a result of designating a person for election as a director for any act or omission by such designated person in
his or her capacity as a director of the Company, nor shall any Stockholder have any liability as a result of voting for any such designee in accordance with the provisions of this Agreement. 

1.6. No “Bad Actor” Designees. Each Person with the right to designate or participate in the designation of a director as
specified above hereby represents and warrants to the Company that, to such Person’s knowledge, none of the “bad actor” disqualifying events described in Rule 506(d)(1)(i)-(viii) promulgated under the

  
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Securities Act of 1933, as amended (the “Securities Act”) (each, a “Disqualification Event”), is applicable to such Person’s initial designee named above
except, if applicable, for a Disqualification Event as to which Rule 506(d)(2)(ii) or (iii) or (d)(3) is applicable. Any director designee to whom any Disqualification Event is applicable, except for a Disqualification Event as to which Rule
506(d)(2)(ii) or (iii) or (d)(3) is applicable, is hereinafter referred to as a “Disqualified Designee”. Each Person with the right to designate or participate in the designation of a director as specified above hereby
covenants and agrees (A) not to designate or participate in the designation of any director designee who, to such Person’s knowledge, is a Disqualified Designee and (B) that in the event such Person becomes aware that any individual
previously designated by any such Person is or has become a Disqualified Designee, such Person shall as promptly as practicable take such actions as are necessary to remove such Disqualified Designee from the Board and designate a replacement
designee who is not a Disqualified Designee. 
 2. Vote to Increase Authorized Common Stock. Each Stockholder agrees to vote
or cause to be voted all Shares owned by such Stockholder, or over which such Stockholder has voting control, from time to time and at all times, in whatever manner as shall be necessary to increase the number of authorized shares of Common Stock
from time to time to ensure that there will be sufficient shares of Common Stock available for conversion of all of the shares of Preferred Stock outstanding at any given time. 

3. Drag-Along Right. 

3.1. Definitions. A “Sale of the Company” shall mean: (a) 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 a majority of the outstanding voting power of the Company (a “Stock Sale”); (b) a SPAC Transaction (as defined in
the Restated Certificate) or (c) a transaction that qualifies as a “Deemed Liquidation Event” as defined in the Restated Certificate. 

3.2. Actions to be Taken. In the event that (a) the holders of a majority of the Preferred Stock, voting together as a single
class on an as-converted to Common Stock basis (collectively, the “Selling Investors”), (b) the Board, and (c) if the Sale of the Company is a SPAC Transaction that is not a Qualified
SPAC Transaction (as defined in the Restated Certificate), the holders of at least two-thirds (2/3rds) of the outstanding shares of Series C Preferred Stock, voting separately as a single class, approve a Sale
of the Company in writing, specifying that this Section 3 shall apply to such transaction, then each Stockholder and the Company hereby agree: 

(a) if such transaction requires stockholder approval, with respect to all Shares that such Stockholder owns or over which such Stockholder
otherwise exercises voting power, to vote (in person, by proxy or by action by written consent, as applicable) all Shares in favor of, and adopt, such Sale of the Company (together with any related amendment to the Restated Certificate required in
order to implement such Sale of the Company) and to vote in opposition to any and all other proposals that could reasonably be expected to delay or impair the ability of the Company to consummate such Sale of the Company; 

(b) if such transaction is a Stock Sale, to sell the same proportion of shares of capital stock of the Company beneficially held by such
Stockholder as is being sold by the Selling Investors to the Person to whom the Selling Investors propose to sell their Shares, and, except as permitted in Section 3.3 below, on the same terms and conditions as the Selling
Investors; 
 (c) to execute and deliver all related documentation and take such other action in support of the Sale of the Company as
shall reasonably be requested by the Company or the Selling Investors in order to carry out the terms and provision of this Section 3, including without limitation executing and delivering instruments of conveyance and
transfer, and any purchase agreement, merger agreement, indemnity agreement, escrow agreement, consent, waiver, governmental filing, share certificates duly endorsed for transfer (free and clear of impermissible liens, claims and encumbrances) and
any similar or related documents; 
 (d) not to deposit, and to cause their Affiliates not to deposit, except as provided in this
Agreement, any Shares of the Company owned by such party or Affiliate in a voting trust or subject any Shares to any arrangement or agreement with respect to the voting of such Shares, unless specifically requested to do so by the acquiror in
connection with the Sale of the Company; 

  
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 (e) to refrain from exercising any dissenters’ rights or rights of appraisal under
applicable law at any time with respect to such Sale of the Company; 
 (f) if the consideration to be paid in exchange for the Shares
pursuant to this Section 3 includes any securities and due receipt thereof by any Stockholder would require under applicable law (x) the registration or qualification of such securities or of any Person as a broker or
dealer or agent with respect to such securities or (y) the provision to any Stockholder of any information other than such information as a prudent issuer would generally furnish in an offering made solely to “accredited investors” as
defined in Regulation D promulgated under the Securities Act, the Company may cause to be paid to any such Stockholder in lieu thereof, against surrender of the Shares which would have otherwise been sold by such Stockholder, an amount in cash equal
to the fair value (as determined in good faith by the Company) of the securities which such Stockholder would otherwise receive as of the date of the issuance of such securities in exchange for the Shares; and 

(g) in the event that the Selling Investors, in connection with such Sale of the Company, appoint a stockholder representative (the
“Stockholder Representative”) with respect to matters affecting the Stockholders under the applicable definitive transaction agreements following consummation of such Sale of the Company, (x) to consent to (i) the
appointment of such Stockholder Representative, (ii) the establishment of any applicable escrow, expense or similar fund in connection with any indemnification or similar obligations, and (iii) the payment of such Stockholder’s pro
rata portion (from the applicable escrow or expense fund or otherwise) of any and all reasonable fees and expenses to such Stockholder Representative in connection with such Stockholder Representative’s services and duties in connection with
such Sale of the Company and its related service as the representative of the Stockholders, and (y) not to assert any claim or commence any suit against the Stockholder Representative or any other Stockholder with respect to any action or
inaction taken or failed to be taken by the Stockholder Representative in connection with its service as the Stockholder Representative, absent fraud or willful misconduct. 

3.3. Exceptions. Notwithstanding the foregoing, a Stockholder will not be required to comply with Section 3.2
above in connection with any proposed Sale of the Company (the “Proposed Sale”) unless: 
 (a) any representations and
warranties to be made by such Stockholder in connection with the Proposed Sale are limited to representations and warranties related to authority, ownership and the ability to convey title to such Shares, including but not limited to representations
and warranties that (i) the Stockholder holds all right, title and interest in and to the Shares such Stockholder purports to hold, free and clear of all liens and encumbrances, (ii) the obligations of the Stockholder in connection with
the transaction have been duly authorized, if applicable, (iii) the documents to be entered into by the Stockholder have been duly executed by the Stockholder and delivered to the acquirer and are enforceable against the Stockholder in
accordance with their respective terms and (iv) neither the execution and delivery of documents to be entered into by such Stockholder in connection with the transaction, nor the performance of such Stockholder’s obligations thereunder,
will cause a breach or violation of the terms of any agreement to which such Stockholder is a party, or any law or judgment, order or decree of any court or governmental agency that applies to such Stockholder; 

(b) the Stockholder shall not be liable for the inaccuracy of any representation or warranty made by any other Person in connection with the
Proposed Sale, other than the Company (except to the extent that funds may be paid out of an escrow established to cover breach of representations, warranties and covenants of the Company as well as breach by any stockholder of any of identical
representations, warranties and covenants provided by all stockholders); 
 (c) the liability for indemnification, if any, of such
Stockholder in the Proposed Sale and for the inaccuracy of any representations and warranties made by the Company in connection with such Proposed Sale, is several and not joint with any other Person (except to the extent that funds may be paid out
of an escrow established to cover breach of representations, warranties and covenants of the Company as well as breach by any stockholder of any of identical representations, warranties, and covenants provided by all stockholders), and, subject to
the provisions of the Restated Certificate related to the allocation of the escrow, is pro rata in proportion to, and does not exceed, the amount of consideration paid to such Stockholder in connection with such Proposed Sale; 

  
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 (d) liability shall be limited to such Stockholder’s applicable share (determined
based on the respective proceeds payable to each Stockholder in connection with such Proposed Sale in accordance with the provisions of the Restated Certificate) of a negotiated aggregate indemnification amount that applies equally to all
Stockholders but that in no event exceeds the amount of consideration paid to such Stockholder in connection with such Proposed Sale, except with respect to claims related to fraud by such Stockholder, the liability for which need not be limited as
to such Stockholder; 
 (e) upon the consummation of the Proposed Sale, (i) each holder of each class or series of the Company’s
stock will receive the same form of consideration for their shares of such class or series as is received by other holders in respect of their shares of such same class or series of stock, (ii) each holder of a series of Preferred Stock will
receive the same amount of consideration per share of such series of Preferred Stock as is received by other holders in respect of their shares of such same series, (iii) each holder of Common Stock will receive the same amount of consideration
per share of Common Stock as is received by other holders in respect of their shares of Common Stock, and (iv) the aggregate consideration receivable by all holders of the Preferred Stock and Common Stock shall be allocated among the holders of
Preferred Stock and Common Stock on the basis of the relative liquidation preferences to which the holders of each respective series of Preferred Stock and the holders of Common Stock are entitled in a Deemed Liquidation Event (assuming for this
purpose that the Proposed Sale is a Deemed Liquidation Event) in accordance with the Company’s Certificate of Incorporation in effect immediately prior to the Proposed Sale, unless the holders of at least a majority of the Preferred Stock,
voting together as a single class on an as-converted to Common Stock basis, elect to not treat such event as a Deemed Liquidation Event by written notice given to the Company at least ten (10) days prior
to the effective date of such Proposed Sale; provided, however, that, notwithstanding the foregoing, (A) the election to not treat such event as a Deemed Liquidation Event shall not apply to (1) the Series B
Preferred Stock unless such electing holders include the holders of a majority of the outstanding Series B Preferred Stock, voting or consenting together as a single class, in accordance with the Company’s Certificate of Incorporation in effect
immediately prior to the Proposed Sale, or (2) the Series C Preferred Stock unless such electing holders include the holders of at least two-thirds
(2/3rds) of the outstanding Series C Preferred Stock, voting or consenting together as a single class, in accordance with the Company’s Certificate of Incorporation in effect immediately
prior to the Proposed Sale, or (B) if the consideration to be paid in exchange for a Key Holder’s Shares or an Investor’s Shares, as applicable, pursuant to this Section 3.3(e) includes any securities and due
receipt thereof by such Key Holder or Investor would require under applicable law (x) the registration or qualification of such securities or of any Person as a broker or dealer or agent with respect to such securities or (y) the provision
to such Key Holder or Investor of any information other than such information as a prudent issuer would generally furnish in an offering made solely to “accredited investors” as defined in Regulation D promulgated under the Securities Act,
the Company may cause to be paid to any such Key Holder or Investor in lieu thereof, against surrender of such Key Holder’s Shares or such Investor’s Shares, as applicable, which would have otherwise been sold by such Key Holder or
Investor, an amount in cash equal to the fair value (as determined in good faith by the Board) of the securities which such Key Holder or Investor would otherwise receive as of the date of the issuance of such securities in exchange for such Key
Holder’s Shares or such Investor’s Shares, as applicable; 
 (f) subject to clause (e) above, requiring the same form of
consideration to be available to the holders of any single class or series of capital stock, if any holders of any capital stock of the Company are given an option as to the form and amount of consideration to be received as a result of the Proposed
Sale, all holders of such capital stock will be given the same option; provided, however, that nothing in this Section 3.3(f) shall entitle any holder to receive any form of consideration that such
holder would be ineligible to receive as a result of such holder’s failure to satisfy any condition, requirement or limitation that is generally applicable to the Company’s stockholders; and 

(g) the Stockholder is not required to agree (unless such Stockholder is a Company officer or employee) to any restrictive covenant in
connection with the Proposed Sale (including, without limitation, any covenant not to compete or covenant not to solicit customers, employees or suppliers of any party to the Proposed Sale) or any release of claims other than a release in customary
form of claims arising solely in such Stockholder’s capacity as a stockholder of the Company. 
 3.3A Strategic Investor
Exception. Notwithstanding anything in Section 3.2 to the contrary, no Strategic Investor will be required to comply with Section 3.2 above in connection with any Proposed Sale unless such

  
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Strategic Investor shall not be required to amend, extend or terminate (x)(i) with respect to AbbVie Inc. and its Affiliates (“AbbVie”), that certain Collaboration and License
Agreement, dated as of February 9, 2021, by and between AbbVie Manufacturing Management Unlimited Company and the Company, (ii) with respect to Genus plc (“Genus”), that certain Research Collaboration and License
Agreement, dated May 12, 2016, as amended, between the Company and Genus plc and its Affiliates, including all entities within the Agroceres PIC joint venture in Latin America and within the Besun joint venture in China, (iii) with respect
to Corteva, the Amended and Restated Collaboration and License Agreement, dated July 13, 2015, as amended, by and between Pioneer Hi-Bred International, Inc. (a member of the Corteva Agriscience
group of companies; “Corteva”) and the Company, or (iv) with respect to Novartis, that certain Research Collaboration and License Agreement, dated December 2, 2014, as amended, by and between Novartis Institutes for
BioMedical Research, Inc. (“Novartis”) and the Company, as any of the foregoing may be amended, modified or supplemented, or (y) any other commercial contracts with the Company, the acquirer or their respective Affiliates. For
purposes of this Section 3.3A, “Strategic Investor” shall mean any one of AbbVie, Genus plc, Corteva, and Novartis. 

3.4. Restrictions on Sales of Control of the Company. No Stockholder shall be a party to any Stock Sale unless all holders of Preferred
Stock are allowed to participate in such transaction and the consideration received pursuant to such transaction is allocated among the parties thereto in the manner specified in the Company’s Certificate of Incorporation in effect immediately
prior to the Stock Sale (as if such transaction were a Deemed Liquidation Event), unless the holders of at least a majority of the Preferred Stock, voting together as a single class on an as-converted to
Common Stock basis, elect to not treat such event as a Deemed Liquidation Event by written notice given to the Company at least ten (10) days prior to the effective date of such Stock Sale; provided, however, the election to not
treat such event as a Deemed Liquidation Event shall not apply to (a) the Series B Preferred Stock unless such electing holders include the holders of a majority of the outstanding Series B Preferred Stock, voting or consenting together as a
single class, in accordance with the Company’s Certificate of Incorporation in effect immediately prior to such Stock Sale, or (b) the Series C Preferred Stock unless such electing holders include the holders of at least two-thirds (2/3rds) of the outstanding Series C Preferred Stock, voting or consenting together as a single class, in accordance with the Company’s
Certificate of Incorporation in effect immediately prior to such Stock Sale. 
 4. Remedies. 

4.1. Covenants of the Company. The Company agrees to use its commercially reasonable efforts, within the requirements of applicable
law, to ensure that the rights granted under this Agreement are effective and that the parties enjoy the benefits of this Agreement. Such actions include, without limitation, the use of the Company’s commercially reasonable efforts to cause the
nomination and election of the directors as provided in this Agreement. 
 4.2. Irrevocable Proxy and Power of Attorney. Each party
to this Agreement hereby constitutes and appoints as the proxies of the party and hereby grants a power of attorney to the President of the Company, with respect to the matters set forth in Section 1.2, the party entitled
to designate the director in question and a designee of the Selling Investors, and each of them, with full power of substitution, with respect to the matters set forth herein, including without limitation, election of persons as members of the Board
in accordance with Section 1 hereto, votes to increase authorized shares pursuant to Section 2 hereof and votes regarding any Sale of the Company pursuant to Section 3
hereof, and hereby authorizes each of them to represent and to vote, if and only if the party (i) fails to vote or (ii) attempts to vote (whether by proxy, in person or by written consent), in a manner which is inconsistent with the terms
of this Agreement, all of such party’s Shares in favor of the election of persons as members of the Board determined pursuant to and in accordance with the terms and provisions of this Agreement or the increase of authorized shares or approval
of any Sale of the Company pursuant to and in accordance with the terms and provisions of Sections 1, 2 and 3, respectively, of this Agreement or to take any action necessary to effect Sections 1, 2 and 3,
respectively, of this Agreement. Each of the proxy and power of attorney granted pursuant to the immediately preceding sentence is given in consideration of the agreements and covenants of the Company and the parties in connection with the
transactions contemplated by this Agreement and, as such, each is coupled with an interest and shall be irrevocable unless and until this Agreement terminates or expires pursuant to Section 5 hereof. Each party hereto
hereby revokes any and all previous proxies or powers of attorney with respect to the Shares and shall not hereafter, unless and until this Agreement terminates or expires pursuant to Section 5 hereof, purport to grant any
other proxy or power of attorney with respect to any of the Shares, deposit any of the Shares into a voting trust or enter into any agreement 

  
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(other than this Agreement), arrangement or understanding with any Person, directly or indirectly, to vote, grant any proxy or give instructions with respect to the voting of any of the Shares,
in each case, with respect to any of the matters set forth herein. 
 4.3. Specific Enforcement. Each party acknowledges and agrees
that each party hereto will be irreparably damaged in the event any of the provisions of this Agreement are not performed by the parties in accordance with their specific terms or are otherwise breached. Accordingly, it is agreed that each of the
Company and the Stockholders shall be entitled to an injunction to prevent breaches of this Agreement, and to specific enforcement of this Agreement and its terms and provisions in any action instituted in any court of the United States or any state
having subject matter jurisdiction. 
 4.4. Remedies Cumulative. All remedies, either under this Agreement or by law or otherwise
afforded to any party, shall be cumulative and not alternative. 
 5. Term. This Agreement shall be effective as of the date hereof
and shall continue in effect until and shall terminate upon the earliest to occur of (a) the consummation of the Company’s first underwritten public offering of its Common Stock (other than a registration statement relating either to the
sale of securities to employees of the Company pursuant to its stock option, stock purchase or similar plan or an SEC Rule 145 transaction); (b) the consummation of a Sale of the Company and distribution of proceeds to or escrow for the benefit of
the Stockholders in accordance with the Restated Certificate, provided that the provisions of Section 3 hereof will continue after the closing of any Sale of the Company to the extent necessary to enforce the provisions of
Section 3 with respect to such Sale of the Company; (c) the consummation of a SPAC Transaction; and (d) termination of this Agreement in accordance with Section 6.8 below. 

6. Miscellaneous. 
 6.1.
Additional Parties. 
 (a) Notwithstanding anything to the contrary contained herein, if the Company issues additional shares of
Series C Preferred Stock after the date hereof, as a condition to the issuance of such shares, the Company shall require that any purchaser of Series C Preferred Stock become a party to this Agreement by executing and delivering (i) the
Adoption Agreement attached to this Agreement as Exhibit A, or (ii) a counterpart signature page hereto agreeing to be bound by and subject to the terms of this Agreement as an Investor and Stockholder hereunder. In either event, each
such Person shall thereafter be deemed an Investor and Stockholder for all purposes under this Agreement. 
 (b) In the event that after
the date of this Agreement, the Company enters into an agreement with any Person to issue shares of capital stock to such Person (other than to a purchaser of Preferred Stock described in Section 6.1(a) above), following
which such Person shall hold Shares constituting one percent (1%) or more of the Company’s then outstanding capital stock (treating for this purpose all shares of Common Stock issuable upon exercise of or conversion of outstanding options,
warrants or convertible securities, as if exercised and/or converted or exchanged), then the Company shall cause such Person, as a condition precedent to entering into such agreement, to become a party to this Agreement by executing an Adoption
Agreement in the form attached hereto as Exhibit A, agreeing to be bound by and subject to the terms of this Agreement as a Stockholder and thereafter such Person shall be deemed a Stockholder for all purposes under this Agreement. 

6.2. Transfers. Each transferee or assignee of any Shares subject to this Agreement shall continue to be subject to the terms hereof,
and, as a condition precedent to the Company’s recognizing such transfer, each transferee or assignee shall agree in writing to be subject to each of the terms of this Agreement by executing and delivering an Adoption Agreement substantially in
the form attached hereto as Exhibit A. Upon the execution and delivery of an Adoption Agreement by any transferee, such transferee shall be deemed to be a party hereto as if such transferee were the transferor and such transferee’s
signature appeared on the signature pages of this Agreement and shall be deemed to be an Investor and Stockholder, or Key Holder and Stockholder, as applicable. The Company shall not permit the transfer of the Shares subject to this Agreement on its
books or issue a new certificate representing any such Shares unless and until such transferee shall have complied with the terms of this Section 6.2. Each certificate representing the Shares subject to this Agreement if
issued on or after the date of this Agreement shall be endorsed by the Company with the legend set forth in Section 6.12. 

  
 8 

 6.3. Successors and Assigns. The terms and conditions of this Agreement shall inure
to the benefit of and be binding upon the respective successors and assigns of the parties. Nothing in this Agreement, express or implied, is intended to confer upon any party other than the parties hereto or their respective successors and assigns
any rights, remedies, obligations, or liabilities under or by reason of this Agreement, except as expressly provided in this Agreement. 

6.4. 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. 
 6.5. 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. 

6.6. 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. 
 6.7. Notices. 

(a) 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 Schedule A or Schedule B
hereto, or to such email address, facsimile number or address as subsequently modified by written notice given in accordance with this Section 6.7. If notice is given to the Company, it shall be sent to Caribou Biosciences,
Inc., 2929 7th Street, Suite 105, Berkeley, CA 94710, email: legalnotices@cariboubio.com, Attention: Chief Legal Officer; and a copy (which shall not constitute notice) shall also be sent to Reed Smith LLP, 1901 Avenue of the Stars, Suite 700, Los
Angeles, California 90067, email amukhey@reedsmith.com, Attention: Ashok Mukhey, Esq., and if notice is given to Investors, a copy shall also be given to such counsel as may appear with such Investors’ address on Schedule A hereto. 

(b) Each Investor and Key Holder consents to the delivery of any stockholder notice pursuant to the Delaware General Corporation Law (the
“DGCL”), as amended or superseded from time to time, or under this Agreement by electronic transmission pursuant to Section 232 of the DGCL (or any successor thereto) at the email address set forth below such Investor’s or
Key Holder’s name on the Schedules hereto, as updated from time to time by notice to the Company or as on the books of the Company. Each Investor and Key Holder agrees to promptly notify the Company of any change in its email address, and the
failure to do so shall not affect the foregoing. 
 6.8. Consent Required to Amend, Terminate or Waive. This Agreement may be amended
or terminated 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 the shares of Common Stock then held by the Key Holders who are then employed by the Company; and (c) the holders of at least a majority of the shares of Common Stock issued or issuable upon conversion of the shares
of Preferred Stock held by the Investors (voting as a single class and on an as-converted to Common Stock basis). Notwithstanding the foregoing: 

(a) this Agreement may not be amended or terminated and the observance of any term of this Agreement 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, termination or waiver applies to all Investors or Key Holders, as the case may be, in the same fashion; 

  
 9 

 (b) the consent of the Key Holders shall not be required for any amendment or waiver if
such amendment or waiver either (A) is not applicable to the rights of the Key Holders hereunder or (B) does not adversely affect the rights of the Key Holders in a manner that is different than the effect on the rights of the other
parties herein; 
 (c) Schedule A hereto may be amended by the Company from time to time in accordance with
Section 1.3 of the Purchase Agreement to add information regarding Additional Purchasers (as defined in the Purchase Agreement) without the consent of the other parties hereto; 

(d) any provision hereof may be waived by the waiving party on such party’s own behalf, without the consent of any other party; 

(e) (i) Section 1.2(a) and Section 1.4(a) of this Agreement (with respect to F-Prime), and this clause (i) shall not be amended or waived without the written consent of F-Prime, (ii) Section 1.2(b)(i) and
Section 1.4(a) of this Agreement (with respect to PFM) and this clause (ii) shall not be amended or waived without the written consent of PFM, (iii) Section 1.2(b)(ii) and
Section 1.4(a) of this Agreement (with respect to Ridgeback), and this clause (iii) shall not be amended or waived without the written consent of Ridgeback, (iv) the rights of Farallon under
Section 1.2(b) and Section 1.4(a) of this Agreement (with respect to Farallon), and this clause (iv) shall not be amended or waived without the written consent of Farallon,
(v) Section 1.2(c) of this Agreement and this clause (v) may not be amended, terminated or waived without the prior written consent of the holders of a majority of the shares of Common Stock,
(vi) Section 1.2(d) of this Agreement and this clause (vi) shall not be amended, terminated or waived without the prior written consent of the holders of a majority of the shares of Common Stock and Preferred
Stock, voting together as a single class on an as-converted to Common Stock basis, and the approval of a majority of the Directors then in office, provided, however, that the right to approve the initial
appointment of the Independent Directors shall not amended, terminated or waived without the approval of a majority of the Preferred Directors then in office, and (vii) Section 1.4(a)(i)(B) of this Agreement and this
clause (vii) shall not be amended, terminated or waived without the prior written consent of the holders of a majority of the shares of Common Stock and Preferred Stock, voting together as a single class on an
as-converted to Common Stock basis and the approval of a majority of the Directors then in office; 

(f) Section 3 and Section 3.4 of this Agreement shall not be amended or waived without the written consent
of (i) the holders of a majority of the Series B Preferred Stock, voting together as a single class, and (ii) the holders of at least two-thirds (2/3rds) of the Series C Preferred Stock, voting
together as a single class; provided, however, that the consent of the holders of the Series B Preferred Stock or the holders of the Series C Preferred Stock, respectively, shall not be required for any amendment, modification,
termination or waiver if such amendment, modification, termination, or waiver is not directly applicable to the rights of the holders of the Series B Preferred Stock or the holders of the Series C Preferred Stock, as the case may be; and 

(g) Section 3.3A(x)(i), Section 3.3(g) (with respect to AbbVie) and this clause (g) (with
respect to AbbVie) shall not be amended, terminated, or waived without the written consent of AbbVie Inc.; Section 3.3A(x)(ii) and this clause (g) (with respect to Genus) shall not be amended, terminated, or waived without
the written consent of Pig Improvement Company UK Limited; Section 3.3A(x)(iii) and this clause (g) (with respect to Corteva) shall not be amended, terminated, or waived without the written consent of Corteva; and
Section 3.3A(x)(iv) and this clause (g) (with respect to Novartis) shall not be amended, terminated, or waived without the written consent of Novartis. 

The Company shall give prompt written notice of any amendment, termination, or waiver hereunder to any party that did not consent in writing
thereto. Any amendment, termination or waiver effected in accordance with this Section 6.8 shall be binding on each party and all of such party’s successors and permitted assigns, whether or not any such party,
successor or assignee entered into or approved such amendment, termination or waiver. For purposes of 

  
 10 

 
this Section 6.8, the requirement of a written instrument may be satisfied in the form of an action by written consent of the Stockholders circulated by the Company and
executed by the Stockholder parties specified, whether or not such action by written consent makes explicit reference to the terms of this Agreement. 

6.9. 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 previously 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. 
 6.10. Severability. The invalidity or unenforceability of any provision hereof shall in no way affect the validity or
enforceability of any other provision. 
 6.11. Entire Agreement. Upon the effectiveness of this Agreement, the Prior Agreement shall
be deemed amended and restated to read in its entirety as set forth in this Agreement. This Agreement (including the Exhibits hereto), and the Restated Certificate and the other Transaction Agreements (as defined in the Purchase Agreement)
constitute 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 is expressly
canceled. 
 6.12. Legend on Share Certificates. Each certificate representing any Shares issued after the date hereof shall be
endorsed by the Company with a legend reading substantially as follows: 
 “THE SHARES EVIDENCED HEREBY ARE SUBJECT TO A VOTING
AGREEMENT, AS MAY BE AMENDED FROM TIME TO TIME, (A COPY OF WHICH MAY BE OBTAINED UPON WRITTEN REQUEST FROM THE COMPANY), AND BY ACCEPTING ANY INTEREST IN SUCH SHARES THE PERSON ACCEPTING SUCH INTEREST SHALL BE DEEMED TO AGREE TO AND SHALL BECOME
BOUND BY ALL THE PROVISIONS OF THAT VOTING AGREEMENT, INCLUDING CERTAIN RESTRICTIONS ON TRANSFER AND OWNERSHIP SET FORTH THEREIN.” 
 The Company, by
its execution of this Agreement, agrees that it will cause the certificates evidencing the Shares issued after the date hereof to bear the legend required by this Section 6.12 of this Agreement, and it shall supply, free of
charge, a copy of this Agreement to any holder of a certificate evidencing Shares upon written request from such holder to the Company at its principal office. The parties to this Agreement do hereby agree that the failure to cause the certificates
evidencing the Shares to bear the legend required by this Section 6.12 herein and/or the failure of the Company to supply, free of charge, a copy of this Agreement as provided hereunder shall not affect the validity or
enforcement of this Agreement. 
 6.13. Stock Splits, Stock Dividends, etc. In the event of any issuance of Shares of the
Company’s voting securities hereafter to any of the Stockholders (including, without limitation, in connection with any stock split, stock dividend, recapitalization, reorganization, or the like), such Shares shall become subject to this
Agreement and shall be endorsed with the legend set forth in Section 6.12. 
 6.14. Manner of Voting. The
voting of Shares pursuant to this Agreement may be effected in person, by proxy, by written consent or in any other manner permitted by applicable law. For the avoidance of doubt, voting of the Shares pursuant to the Agreement need not make explicit
reference to the terms of this Agreement. 
 6.15. Further Assurances. At any time or from time to time after the date hereof, the
parties agree to cooperate with each other, and at the request of any other party, to execute and deliver any further instruments 

  
 11 

 
or documents and to take all such further action as the other party may reasonably request in order to evidence or effectuate the consummation of the transactions contemplated hereby and to
otherwise carry out the intent of the parties hereunder. 
 6.16. 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. 
 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. 
 6.17. Costs of
Enforcement. If any party to this Agreement seeks to enforce its rights under this Agreement by legal proceedings, the non-prevailing party shall pay all costs and expenses incurred by the prevailing
party, including, without limitation, all reasonable attorneys’ fees. 
 6.18. Aggregation of Stock. All Shares held or acquired
by a Stockholder and/or its Affiliates 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. 
 6.19. Spousal Consent. If any individual Stockholder is married on the date of this Agreement and resides in a
community property state, such Stockholder’s spouse shall execute and deliver to the Company a consent of spouse in the form of Exhibit B 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 Stockholder’s Shares that do not otherwise exist by operation of law or the agreement of the parties. If any individual
Stockholder should marry or remarry subsequent to the date of this Agreement, such Stockholder 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. 

6.20. Tekla Funds. A copy of the Declaration of Trust, as amended and restated, for each of Tekla Healthcare Investors and Tekla Life
Sciences Investors (together, the “Tekla Funds”) is on file with the Secretary of State of The Commonwealth of Massachusetts, and notice is hereby given that this Agreement is executed on behalf of the Tekla Funds by an officer or
trustee of the Tekla Funds in his or her capacity as an officer or trustee of the Tekla Funds, and not individually and that the obligations of or arising out of this Agreement are not binding upon any of the trustees, officers or shareholders
individually but are binding only upon the assets and property of each of the respective Tekla Funds. 
 [Signature Page Follows] 

  
 12 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	COMPANY:
	
	CARIBOU BIOSCIENCES, INC.
		
	By:	 	 /s/ Rachel E. Haurwitz

	Name:	 	 Rachel E. Haurwitz

	Title:	 	 President and Chief Executive Officer

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	PFM HEALTH SCIENCES, LP
		
	By:	 	 /s/ Yuan DuBord

	Name:	 	 Yuan DuBord

	Title:	 	 Chief Financial Officer

	
	INVESTORS:
	
	PFM HEALTHCARE MASTER FUND, L.P.
	
	By: PFM Health Sciences, LP, its investment advisor
		
	By:	 	 /s/ Yuan DuBord

	Name:	 	 Yuan DuBoard

	Title:	 	 Chief Financial Officer

	
	PARTNER INVESTMENTS, L.P.,
	
	By: PFM Health Sciences, LP, its investment advisor
		
	By:	 	 /s/ Yuan DuBord

	Name:	 	 Yuan DuBoard

	Title:	 	 Chief Financial Officer

PFM HEALTHCARE GROWTH EQUITY HOLDINGS I, LLC 

By: PFM Health Sciences, LP, its investment advisor 
  

			
	By:	 	 /s/ Yuan DuBord

	Name:	 	 Yuan DuBoard

	Title:	 	 Chief Financial Officer

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	ZONE III HEALTHCARE HOLDINGS, LLC
	
	By: Farallon Capital Management , L.L.C., its Manager
		
	By:	 	 /s/ Philip Dreyfuss

	Name:	 	 Philip Dreyfuss

	Title:	 	 Authorized Signatory

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	RIDGEBACK CAPITAL INVESTMENTS LP
	by RIDGEBACK CAPITAL MANAGEMENT LLC its Fund Manager:
		
	By:	 	 /s/ Christian Sheldon

	Name:	 	 Christian Sheldon

	Title:	 	 COO

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	AbbVie Inc.
		
	By:	 	 /s/ Adam Houghton

	Name:	 	 Adam Houghton

	Title:	 	 VP & Head, AbbVie Ventures

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	MAVERICK VENTURES INVESTMENT FUND, L.P.
	
	By: Maverick Capital Ventures, LLC, its General Partner
	By: Maverick Capital Advisors, L.P., its Manager
		
	By:	 	 /s/ Ginessa Avila

	Name:	 	 Ginessa Avila

	Title:	 	 Authorized Signatory

	
	MAVERICK ADVISORS FUND, L.P.
	
	By: Maverick Capital Ventures, LLC, its General Partner
	By: Maverick Capital Advisors, L.P., its Manager
		
	By:	 	 /s/ Ginessa Avila

	Name:	 	 Ginessa Avila

	Title:	 	 Authorized Signatory

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
 INVESTORS: 

Adage Capital Partners, LP 
 By: Adage Capital
Partners, GP, LLC, it’s General Partner 
 By: Adage Capital Advisors, LLC, it’s Managing Member 

 

			
	By:	 	 /s/ Dan Lehan

	Name:	 	 Dan Lehan

	Title:	 	 Chief Operating Officer

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	Monashee Solitario Fund LP
		
	By:	 	 /s/ Jeff Muller

	Name:	 	 Jeff Muller

	Title:	 	 COO

	
	DS Liquid Div RVA MON LLC
		
	By:	 	 /s/ Jeff Muller

	Name:	 	 Jeff Muller

	Title:	 	 COO

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	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

	
	Janus Henderson Biotech Innovation Master Fund Limited
	
	By: Janus Capital Management LLC, its investment advisor
		
	By:	 	 /s/ Andrew Acker

	Name:	 	 Andrew Acker

	Title:	 	 Authorized Signatory

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	LLS TAP, LLC
		
	By:	 	 /s/ Louis DeGennaro

	Name:	 	 Louis DeGennaro

	Title:	 	 President & CEO

		
	By:	 	 /s/ Gordon Miller

	Name:	 	 Gordon Miller

	Title:	 	 EVP & CFO

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	AngelList-Cces-Fund, a series of AngelList-JR-Funds, LLC
		
	By:	 	 /s/ Brett Sagan

	Name:	 	 Brett Sagan

	Title:	 	 Authorized Person

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
 INVESTORS: 

AngelList-Cces-PR-Fund, a series of AngelList-JR-Funds, LLC 
  

			
	By:	 	 /s/ Brett Sagan

	Name:	 	 Brett Sagan

	Title:	 	 Authorized Person

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	Central Valley Administrators, Inc.
		
	By:	 	 /s/ Richard Merkin

	Name:	 	 Richard Merkin

	Title:	 	 President

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	CAROLEM CAPITAL LLC
		
	By:	 	 /s/ Michael Karlin

	Name:	 	 Michael Karlin

	Title:	 	 Manager

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	NRG CAPITAL HOLDINGS LLC
		
	By:	 	 /s/ Michael Karlin

	Name:	 	 Michael Karlin

	Title:	 	 Manager

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	Tekla Healthcare Investors*
		
	By:	 	 /s/ Daniel R. Omstead

	Name:	 	 Daniel R. Omstead

	Title:	 	 President

  

	*	 The name Tekla Healthcare Investors is the designation of the Trustees for the time being under an
Amended & Restated Declaration of Trust dated April 21, 1987, as amended, and all persons dealing with Tekla Healthcare Investors must look solely to the trust property for the enforcement of any claim against Tekla Healthcare
Investors, as neither the Trustees, officers nor shareholders assume any personal liability for the obligations entered into on behalf of Tekla Healthcare Investors. 

 

			
	Tekla Life Sciences Investors*
		
	By:	 	 /s/ Daniel R. Omstead

	Name:	 	 Daniel R. Omstead

	Title:	 	 President

  

	*	 The name Tekla Life Sciences Investors is the designation of the Trustees for the time being under a
Declaration of Trust dated February 20, 1992, as amended, and all persons dealing with Tekla Life Sciences Investors must look solely to the trust property for the enforcement of any claim against Tekla Life Sciences Investors, as neither the
Trustees, officers nor shareholders assume any personal liability for the obligations entered into on behalf of Tekla Life Sciences Investors. 

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	PONTIFAX GLOBAL FOOD AND AGRICULTURE TECHNOLOGY FUND, L.P.
		
	By:	 	 /s/ Benjamin Belldegrun

	Name:	 	 Benjamin Belldegrun

	Title:	 	 Managing Partner

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	Point72 Biotech Private Investments, LLC
		
	By:	 	 /s/ Vincent Tortorella

	Name:	 	 Vincent Tortorella

	Title:	 	 Authorized Signatory

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	Jenny Rooke
		
	By:	 	 /s/ Jenny Rooke

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	WS Investment Company, LLC (21A)
		
	By:	 	 /s/ James Terranova

	Name:	 	  

	Title:	 	  

	
	WS Investment Company, LLC (2014A)
		
	By:	 	 /s/ James Terranova

	Name:	 	  

	Title:	 	  

	
	WS Investment Company, LLC (2015A)
		
	By:	 	 /s/ James Terranova

	Name:	 	  

	Title:	 	  

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	Pig Improvement UK Limited
		
	By:	 	 /s/ Stephen Wilson

	Name:	 	 Stephen Wilson

	Title:	 	 CEO

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	James and Jennifer Doudna Cate Living Trust DTD 01/02/2014
		
	By:	 	 /s/ Jennifer Doudna

	Name:	 	 Jennifer Doudna

	Title:	 	 Trustee

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	Rodolphe and Lisa Barrangou
		
	By:	 	 /s/ Rodolphe Barrangou

	By:	 	 /s/ Lisa Barrangou

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	James Berger & Marian Feldman
		
	By:	 	 /s/ James Berger

		
	By:	 	 /s/ Marian Feldman

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	E. I. du Pont de Nemours and Company
		
	By:	 	 /s/ George J. Duko

	Name:	 	 George J. Duko

	Title:	 	 Vice President, Mergers & Acquistions

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	INVESTORS:
	
	LifeSci Venture Partners II, LP
		
	By:	 	 /s/ Paul Yook

	Name:	 	 Paul Yook

	Title:	 	 Managing Member

	
	LifeSci Venture Master SPV, LLC
		
	By:	 	 /s/ Paul Yook

	Name:	 	 Paul Yook

	Title:	 	 Managing Member

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
 INVESTORS: 
  

			
	 Pacific Continental Investment Company, LLC

		
	By:	 	 /s/ Marc Stridiron

	Name:	 	 Marc Stridiron

	Title:	 	 Portfolio Manager

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
 INVESTORS: 
  

			
	Mintz Levin Special Investments Fund LLC
		
	By:	 	 /s/ Megan N. Gates

	Name:	 	 Megan N. Gates

	Title:	 	 Member

	
	Mintz Levin Special Investments Fund LLC - Series FY21
		
	By:	 	 /s/ Megan N. Gates

	Name:	 	 Megan N. Gates

	Title:	 	 Member

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
 INVESTORS: 
  

			
	Anterra F&A Ventures I Coöperatief U.A.
		
	By:	 	 /s/ Adam Anders

	Name:	 	 Adam Anders

	Title:	 	 Director

		
	By:	 	 /s/ Maarten Goossens

	Name:	 	 Maarten Goossens

	Title:	 	 Director

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
 INVESTORS: 
  

			
	F-PRIME CAPITAL PARTNERS HEALTHCARE FUND IV LP
	
	By: F-Prime Capital Partners Healthcare Advisors Fund IV LP, its General Partner
	By: Impresa Holdings LLC, its General Partner
	By: Impresa Management LLC, its Managing Member
		
	By:	 	 /s/ Mary Bevelock Pendergast

	Name:	 	 Mary Bevelock Pendergast

	Title:	 	 Vice President

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
 INVESTORS: 
  

			
	Novartis Institutes for BioMedical Research, Inc.
		
	By:	 	 /s/ Scott A. Brown

	Name:	 	 Scott A. Brown

	Title:	 	 VP CAO

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
 INVESTORS: 
  

			
	Zachary A. Robbins Trust dtd December 31, 1987
		
	By:	 	 /s/ Rich Robbins

	Name:	 	 Rich Robbins

	Title:	 	 Trustee

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
 INVESTORS: 
  

			
	Robbins Family Trust of 1986
		
	By:	 	 /s/ Rich Robbins

	Name:	 	 Rich Robbins

	Title:	 	 Trustee

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
 INVESTORS: 
  

			
	Avidity Master Fund LP
		
	By:	 	 /s/ Michael Gregory

	Name:	 	 Michael Gregory

	Title:	 	 Director

	
	Avidity Capital Fund II LP
		
	By:	 	 /s/ Michael Gregory

	Name:	 	 Michael Gregory

	Title:	 	 Director

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
 INVESTORS: 
  

			
	Lucas Hamilton Robbins Trust dtd November 17, 1997
		
	By:	 	 /s/ Rich Robbins

	Name:	 	 Rich Robbins

	Title:	 	 Trustee

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
 INVESTORS: 
  

			
	Avego Bioscience Capital, L.P.
	By: Avego Bioscience Capital GP, LLC, its general partner
		
	By:	 	 /s/ James Flexner

	Name:	 	 James Flexner

	Title:	 	 Managing Partner

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
 INVESTORS: 
  

			
	INVUS PUBLIC EQUITIES, L.P.
		
	By:	 	 /s/ Raymond Debbane

	Name:	 	 Raymond Debbane

	Title:	 	 President of its General Partner

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
 INVESTORS: 
  

			
	CA Fund I, a series of 5 Prime Ventures, LP
	By: Fund GP, LLC its General Partner
	By: Belltower Fund Group, Ltd. Manager of the General Partner
		
	By:	 	 /s/ Brett Sagan

	Name:	 	 Brett Sagan

	Title:	 	 Authorized Person

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
 INVESTORS: 
  

			
	HEALTHCARE INNOVATION INVESTMENT FUND LLC
		
	By:	 	 /s/ Joseph R. Gentile

	Name:	 	 Joseph R. Gentile

	Title:	 	 Manager

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 IN WITNESS WHEREOF, the parties have executed this Third Amended and Restated Voting
Agreement as of the date first written above. 
  

			
	KEY HOLDER:
		
	By:	 	 /s/ James Berger

	James Berger
		
	By:	 	 /s/ Jennifer Doudna

	Jennifer Doudna
		
	By:	 	 /s/ Rachel E. Haurwitz

	Rachel E. Haurwitz
		
	By:	 	 /s/ Martin Jinek

	Martin Jinek
		
	By:	 	  

	Andrew May

  
 SIGNATURE PAGE TO
THIRD AMENDED AND RESTATED VOTING AGREEMENT 

 SCHEDULE A 

INVESTORS 

 SCHEDULE B 

KEY HOLDERS 

 EXHIBIT A 

ADOPTION AGREEMENT 
 This
Adoption Agreement (“Adoption Agreement”) is executed on                     , 20    , by the undersigned (the
“Holder”) pursuant to the terms of that certain Third Amended and Restated Voting Agreement, dated as of                 , 2021 (the
“Agreement”), by and among the Company and certain of its Stockholders, as such Agreement may be amended or amended and restated hereafter. Capitalized terms used but not defined in this Adoption Agreement shall have the respective
meanings ascribed to such terms in the Agreement. By the execution of this Adoption Agreement, the Holder agrees as follows. 
 1.1
Acknowledgement. Holder acknowledges that Holder is acquiring certain shares of the capital stock of the Company (the “Stock”) or options, warrants or other rights to purchase such Stock (the “Options”), for
one of the following reasons (Check the correct box): 
  

	 	☐	 as a transferee of Shares from a party in such party’s capacity as an “Investor” bound by the
Agreement, and after such transfer, Holder shall be considered an “Investor” and a “Stockholder” for all purposes of the Agreement. 

  

	 	☐	 as a transferee of Shares from a party in such party’s capacity as a “Key Holder” bound by the
Agreement, and after such transfer, Holder shall be considered a “Key Holder” and a “Stockholder” for all purposes of the Agreement. 

  

	 	☐	 as a new Investor in accordance with Section 6.1(a) of the Agreement, in which case
Holder will be an “Investor” and a “Stockholder” for all purposes of the Agreement. 

  

	 	☐	 in accordance with Section 6.1(b) of the Agreement, as a new party who is not a new
Investor, in which case Holder will be a “Stockholder” for all purposes of the Agreement. 

 1.2
Agreement. Holder hereby (a) agrees that the Stock Options, and any other shares of capital stock or securities required by the Agreement to be bound thereby, shall be bound by and subject to the terms of the Agreement and
(b) adopts the Agreement with the same force and effect as if Holder were originally a party thereto. 
 1.3 Notice. Any notice
required or permitted by the Agreement shall be given to Holder at the address or facsimile number listed below Holder’s signature hereto. 

 

			
	HOLDER:	  	  

			
		
	By:	  	  

	Name and Title of Signatory

			
		
	Address:	  	  

	
	  

			
		
	Facsimile Number:	  	  

 

			
	ACCEPTED AND AGREED:
	
	CARIBOU BIOSCIENCES, INC.
		  	

			
		
	By:	  	  

		
	Title:	  	  

		
		  	

 
 

 EXHIBIT B 

CONSENT OF SPOUSE 
 I,
                    , spouse of
                    , acknowledge that I have read the Third Amended and Restated Voting Agreement, dated as of
                , 2021 (the “Agreement”), to which this Consent is attached as Exhibit B and that I know the contents of the Agreement. I am
aware that the Agreement contains provisions regarding the voting and transfer of shares of capital stock of the Company that my spouse may own, including any interest I might have therein. 

I hereby agree that my interest, if any, in any shares of capital stock of the Company subject to the Agreement shall be irrevocably bound by
the Agreement and further understand and agree that any community property interest I may have in such shares of capital stock of the Company shall be similarly bound by the Agreement. 

I am aware that the legal, financial and related matters contained in the Agreement are complex and that I am free to seek independent
professional guidance or counsel with respect to this Consent. I have either sought such guidance or counsel or determined after reviewing the Agreement carefully that I will waive such right. 

 

							
	Dated:	 	  
	 		 	  

		 		 		 	Name:EX-10.53

 Exhibit 10.53 

FIRST AMENDMENT TO 

THIRD AMENDED AND RESTATED VOTING AGREEMENT 

This First Amendment to Third Amended and Restated Voting Agreement (this “Amendment”), effective as of March 29, 2021,
is made by and among Caribou Biosciences, Inc., a Delaware corporation (the “Company”), PFM Health Sciences, LP and certain stockholders of the Company with reference to that certain Third Amended and Restated Voting Agreement dated
as of March 2, 2021 (the “Voting Agreement”) by and among the holders of the Company’s Series A Preferred Stock, $0.0001 par value per share (“Series A Preferred Stock”), the holders of the Company’s
Series A-1 Preferred Stock, $0.0001 par value per share (“Series A-1 Preferred Stock”), the holders of the Company’s Series B Preferred
Stock, $0.0001 par value per share (the “Series B Preferred Stock”), the holders of the Company’s Series C Preferred Stock, $0.0001 par value per share (the “Series C Preferred Stock;” and referred to herein
collectively with the Series A Preferred Stock, the Series A-1 Preferred Stock, and the Series B Preferred Stock, the “Preferred Stock;” the holders of the Preferred Stock collectively are
referred to herein as the “Investors”), and certain other stockholders of the Company (the “Key Holders;” and together collectively with the Investors, the “Stockholders”). Capitalized terms not
otherwise defined in this Amendment shall have the meanings ascribed to them in the Voting Agreement (without giving effect to this Amendment). 

RECITALS 
 A. The Fourth
Amended and Restated Certificate of Incorporation of the Company provides that the holders of record of the Series A Preferred Stock, Series A-1 Preferred Stock and Series B Preferred Stock, exclusively and as
a single separate class on an as-converted to Common Stock basis, are entitled to elect one (1) director of the Company (the “Series A/A-1/B
Preferred Director”). 
 B. The Voting Agreement, among other things, grants
F-Prime Capital Partners Healthcare Fund IV LP (“F-Prime”) the right, for so long as F-Prime and its Affiliates
(as defined in the Voting Agreement) continue to own beneficially at least 1,019,692 shares of the Common Stock, par value $0.0001 per share, of the Company (the “Common Stock”), including shares of Common Stock issued or issuable
upon conversion of the Series A-1 Preferred Stock), to designate the individual to serve as the Series A/A-1/B Preferred Director (the “Series A/A-1/B Designee”). 
 B. The Company and the Stockholders, at the request of F-Prime, desire to amend the Voting Agreement to provide that the Series A/A-1/B Designee be designated by management of the Company and approved by a majority of the
remaining Board members, in lieu of designation by F-Prime. 
 D. Pursuant to Section 6.8 of
the Voting Agreement, (i) the Voting Agreement may be amended, waived, discharged or terminated only by a written instrument executed by (1) the Company; (2) the Key Holders holding a majority of the shares of Common Stock then
held by the Key Holders who are then employed by the Company; and (3) the holders of at least a majority of the shares of Common Stock issued or issuable upon conversion of the shares of Preferred Stock held by the Investors (voting as a single
class and on an as-converted to Common Stock basis) and (ii) notwithstanding the foregoing, Section 1.2(a), Section 1.4(a) (with respect to F-Prime), and
clause (i) of Section 6.8(e) of the Voting Agreement may not be amended or waived without the written consent of F-Prime. 

E. The Company and the Stockholders (including F-Prime) desire to amend the Voting Agreement
consistent with the above and the undersigned hold the requisite vote to so amend the Voting Agreement, which amendment shall be binding on all parties to the Voting Agreement. 

AGREEMENT 
 NOW,
THEREFORE, in consideration of the foregoing recitals and the mutual promises hereinafter set forth, the parties hereto agree as follows: 

 1. Amendments to the Voting Agreement. The following amendments to the Voting
Agreement shall become effective on March 30, 2021 subsequent to the resignation on such date of Robert Weisskoff as a director of the Company: 

(a) Section 1.2(a) of the Voting Agreement is hereby amended and restated to read in its entirety as follows: 

“One (1) person elected by a majority in interest of the holders of the Series A Preferred Stock, the Series A-1 Preferred Stock and the Series B Preferred Stock, voting together as a single class on an as-converted to Common Stock basis (the “Series A/A-1/B Designee”), who shall be designated by management of the Company and approved by a majority of the other Board members. Following the resignation of Robert Weisskoff as a director of the Company,
the Series A/A-1/B Designee seat shall initially be vacant;” 
 (b) Section 6.8(e)(i) of
the Voting Agreement is hereby amended and restated to read in its entirety as follows: 
 “(e) (i) Section 1.2(a) and
Section 1.4(a) (with respect to the Series A/A-1/B Designee or the persons having the power to designate the Series A/A-1/B Designee) of this Agreement and this
clause (i) shall not be amended or waived without the prior written consent of a majority in interest of the holders of the Series A Preferred Stock, the Series A-1 Preferred Stock, and the Series B
Preferred Stock, voting together as a single class on an as-converted to Common Stock basis,” 

2. No Further Amendment. Except as herein provided, the Voting Agreement is not being amended or otherwise modified and shall in all
other respects remain unchanged and in full force and effect according to its respective terms. 
 3. Miscellaneous. This Amendment
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. This Amendment and any controversy arising out of or relating to this Amendment 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. 

[Signature Pages Follow] 

  
 2 

 IN WITNESS WHEREOF, the parties have executed this Amendment effective as of the date first
written above. 
 COMPANY: 
  

			
	CARIBOU BIOSCIENCES, INC.
		
	By:	 	 /s/ Rachel E. Haurwitz

	Name:	 	 Rachel E. Haurwitz

	Title:	 	 President and Chief Executive Officer

  
 [Signature Page to First
Amendment to Third Amended and Restated Voting Agreement] 

 IN WITNESS WHEREOF, the parties have executed this Amendment effective as of the date first
written above. 
  

			
	PFM HEALTH SCIENCES, LP
		
	By:	 	 /s/ Yuan DuBord

	Name:	 	 Yuan DuBord

	Title:	 	 Chief Financial Officer

	
	INVESTORS:
	
	PFM HEALTHCARE MASTER FUND, L.P.
	
	By: PFM Health Sciences, LP, its investment advisor
		
	By:	 	 /s/ Yuan DuBord

	Name:	 	 Yuan DuBord

	Title:	 	 Chief Financial Officer

	
	PARTNER INVESTMENTS, L.P.,
	
	By: PFM Health Sciences, LP, its investment advisor
		
	By:	 	 /s/ Yuan DuBord

	Name:	 	 Yuan DuBord

	Title:	 	 Chief Financial Officer

	
	PFM HEALTHCARE GROWTH EQUITY HOLDINGS I, LLC
	
	By: PFM Health Sciences, LP, its investment advisor
		
	By:	 	 /s/ Yuan DuBord

	Name:	 	 Yuan DuBord

	Title:	 	 Chief Financial Officer

  
 [Signature Page to First
Amendment to Third Amended and Restated Voting Agreement] 

 IN WITNESS WHEREOF, the parties have executed this Amendment effective as of the date first
written above. 
 INVESTORS: 
  

			
	ZONE III HEALTHCARE HOLDINGS, LLC
	
	By: Farallon Capital Management, L.L.C., its Manager
		
	By:	 	 /s/ Philip Dreyfuss

	Name:	 	 Philip Dreyfuss

	Title:	 	 Managing Member

  
 [Signature Page to First
Amendment to Third Amended and Restated Voting Agreement] 

 IN WITNESS WHEREOF, the parties have executed this Amendment effective as of the date first
written above. 
 INVESTORS: 
  

			
	RIDGEBACK CAPITAL INVESTMENTS LP
	
	By RIDGEBACK CAPITAL MANAGEMENT LLC its Fund Manager:
		
	By:	 	 /s/ Christian Sheldon

	Name:	 	 Christian Sheldon

	Title:	 	 COO

  
 [Signature Page to First
Amendment to Third Amended and Restated Voting Agreement] 

 IN WITNESS WHEREOF, the parties have executed this Amendment effective as of the date first
written above. 
 INVESTORS: 
  

			
	E.I. du Pont de Nemours and Company
		
	By:	 	 /s/ George J. Duko

	Name:	 	 George J. Duko

	Title:	 	 VP Mergers and Acquisitions

  
 [Signature Page to First
Amendment to Third Amended and Restated Voting Agreement] 

 IN WITNESS WHEREOF, the parties have executed this Amendment effective as of the date first
written above. 
 INVESTORS: 
  

			
	Anterra F&A Ventures I Coöperatief U.A.
		
	By:	 	 /s/ Adam Anders

	Name:	 	 Adam Anders

	Title:	 	 Director

		
	By:	 	 /s/ Maarten Goossens

	Name:	 	 Maarten Goossens

	Title:	 	 Director

  
 [Signature Page to First
Amendment to Third Amended and Restated Voting Agreement] 

 IN WITNESS WHEREOF, the parties have executed this Amendment effective as of the date first
written above. 
 INVESTORS: 
  

			
	F-PRIME CAPITAL PARTNERS HEALTHCARE FUND IV LP
	
	By: F-Prime Capital Partners Healthcare Advisors Fund IV LP, its General Partner
	By: Impresa Holdings LLC, its General Partner
	By: Impresa Management LLC, its Managing Member
		
	By:	 	 /s/ Mary Bevelock Pendergast

	Name:	 	 Mary Bevelock Pendergast

	Title:	 	 Vice President

  
 [Signature Page to First
Amendment to Third Amended and Restated Voting Agreement]

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