Document:

EX-10.43

 Exhibit 10.43 

SCIENTIFIC ADVISORY BOARD AGREEMENT 

This Scientific Advisory Board Agreement (“Agreement”), effective as of June 18, 2012 (“Effective Date”), is made
between Caribou Biosciences, Inc. (“Company”), a Delaware corporation, and Jennifer A. Doudna (“Advisor”) (each may be referred to below individually as a “party” and collectively as the “parties”). 

BACKGROUND/RECITALS 

Advisor is involved in and possesses significant expertise and skill in fields of particular interest to the Company, the Company wishes to
retain Advisor as a member of the Company’s Scientific Advisory Board, and Advisor desires to provide such Services. 
 NOW, THEREFORE,
in consideration of the mutual covenants and undertakings hereinafter set forth, the parties hereto hereby agree as follows: 

AGREEMENT 
 1.
Services 
 (a) In General. In general, Advisor will provide advice, counsel and Services (as defined below) to the
Company’s officers, directors, employees and agents as described below. 
 (b) Services. Advisor will serve on the Scientific
Advisory board of the Company (the “Advisory Board”) and will use reasonable efforts to attend Advisory Board meetings as requested from time-to-time by the
Company’s CEO and to render advice on issues discussed at such meetings, and will advise the Company’s executive officers in furtherance of the Company’s goals and objectives on an as-needed, as-available basis (collectively the “Services”). Any projects or activities Advisor agrees to perform in excess of the scope of Services would be undertaken on a mutually agreed-upon basis outside the
terms of this Agreement. The Company will provide Advisor with reasonable advance notice of Advisory Board meetings. 
 2. Fees and
Expenses. 
 (a) Consideration. The Advisor shall not receive any consideration for the Services rendered by Advisor as described
above. 
 (b) Reimbursement of Expenses. Company shall reimburse Advisor for (i) Advisor’s approved reasonable out-of-pocket expenses incurred in connection with Advisory Board meeting attendance, and (ii) other approved reasonable out-of-pocket expenses directly related to the Services. Advisor shall provide an itemized expense statement for such reimbursable expenses, and payments shall be made by the Company within 30 days of
receipt. 
 3. Term. 

(a) The term of this Agreement will begin on the Effective Date and will end on the fourth anniversary thereof or upon earlier termination as
provided below (the “ Term”). 
 (b) In addition to termination upon expiration, either party may terminate the Agreement at any
time for any reason upon five (5) days prior written notice. 
 4. Confidential Information. 

(a) Each party who receives information hereunder (the “Recipient”) understands that the other party (the “Discloser”) has
disclosed or may disclose the information as described below, which has commercial value in the Discloser’s business and is confidential or proprietary in nature. “Confidential Information” means (i) nonpublic information
which is held by the Discloser as confidential or proprietary and relates to a party’s technology, customers, 

 
business plans, promotional and marketing activities, finances and other business affairs, and (ii) third-party information that a party is obligated to keep confidential. The recipient
shall protect Confidential Information hereunder that: (i) is disclosed in a tangible or visual form and clearly labeled as “Confidential;” or (ii) is disclosed in a non-tangible, visual or
oral form, identified at the time of disclosure as Confidential Information. 
 (b) Nondisclosure and Nonuse. Recipient agrees that
the Confidential Information (i) will not be disclosed to third parties without the prior written consent of the Discloser, and (ii) will be used only in connection with the Services and will not be used in any way that is detrimental to
the Discloser. 
 (c) Exclusions. Confidential Information does not include any information that (i) is or becomes publicly
available without breach of this Agreement, (ii) can be shown to have been known to Recipient at the time of its receipt from the Company, (iii) is received from a third party who did not acquire or disclose such information by a wrongful
or tortuous act, or (iv) can be shown to have been independently developed by the Recipient without reference to any Confidential Information. 

(d) The obligations under this Section 4 shall continue for a period of 5 years after disclosure. 

5. Copyrights/Improvements/Inventions. Advisor acknowledges that all copyright and other intellectual property rights in the products
and technology of Company and the written material relevant thereto belong to and will remain the sole property of the Company, including any improvements or enhancements thereto however generated. Nothing in this Agreement shall be construed as
granting any rights under any patent, copyright or other intellectual property right of the Company, nor shall this Agreement grant Advisor any rights in or to the Company’s Proprietary Information, except the limited right to use the
Proprietary Information in connection with the Services. Advisor further agrees that any inventions, improvements, discoveries, developments, original works of authorship, software, trade secrets or other intellectual property conceived, developed
or reduced to practice by the Advisor in the performance of the Services performed by Advisor under this Agreement (the “Inventions”) is the proprietary property of the Company. Advisor assigns to the Company and its successors and
assigns, without further consideration, Advisor’s right, title and interest in and to the Inventions whether or not patentable or copyrightable, and further agrees to execute all applications for patents and/or copyrights, domestic or foreign,
assignments and other papers necessary to secure and enforce rights related to the Information. 
 6. Nonexclusivity. Notwithstanding
anything to the contrary herein, nothing shall restrict, limit or prevent Advisor from performing services similar in nature to the Services provided hereunder for any third party, both during and after the term of this Agreement. 

7. General Provisions. 

(a) Relationship of the Parties. The parties are independent contractors, and this Agreement shall not be interpreted as creating an
association, joint venture, or partnership relationship between the parties or as imposing any employment, or partnership obligation or liability on either party: Neither party shall have the authority to create or assume any obligation, express or
implied, on behalf of the other party. 
 (b) Use of Name. It is understood that the name of Advisor and their affiliation with the
Company may be required to appear in disclosure documents pursuant to prevailing securities laws, and in other regulatory and administrative filings in the ordinary course of the Company’s business, and where such use is reasonably related to
Advisor’s participation on the Company’s Advisory Board. The Company may disclose that Advisor is a member of the Company’s Advisory Board, using such specific wording in compliance with this provision as it deems appropriate. Advisor
will comment on such specific wording if she believes it is inappropriate, and the parties will work out alternative language. Additionally, Advisor will work with the Company to develop an approved bio or series of bios to describe Advisor
background which may be used by the Company at its discretion in the course of describing her connection with the Company. Any other written or recorded use of the name of Advisor shall require the prior review and approval of Advisor. Also, all use
of the name of Advisor shall cease upon the termination or expiration of this Agreement, except as otherwise required by law or approved in writing by Advisor. 

  
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 (c) No Conflict: Valid and Binding. Each party represents and warrants that neither
the execution of this Agreement nor the performance of their obligations hereunder will result in a violation or breach of any other agreement or obligation by which the party is bound. The Company further represents and warrants that this Agreement
has been duly authorized and upon execution shall be a legally binding obligation of the Company. 
 (d) No Assignment; Survival.
This Agreement may not be assigned, and any attempted assignment shall be void. The following provisions shall survive termination of this Agreement: Sections 4 (“Confidential Information”) (according to its terms), 5
(“Copyrights/Improvements/Inventions”), 6 (“Nonexclusivity”), 7 (“Indemnification”), and 8 (“General Provisions”). 

(e) Miscellaneous. This Agreement shall be governed by the jaws of the State of California excluding its conflict of laws principles,
and the parties agree to the nonexclusive jurisdiction of the state and federal courts in Santa Clara County, California for interpreting and enforcing this Agreement and for all actions arising out of this Agreement. If any provision of this
Agreement is held by a court or other tribunal of competent jurisdiction to be illegal, invalid or unenforceable, that provision shall be limited or eliminated and this Agreement shall otherwise remain in full force and effect. This Agreement
supersedes all prior discussions and writings and constitutes the entire agreement between the parties with respect to the subject matter hereof. No waiver or modification of this Agreement will be binding upon either party unless made in writing
and signed by a duly authorized representative of such party and no failure or delay in enforcing any right will be deemed a waiver. 
 IN
WITNESS WHEREOF, the parties have executed this Agreement as of the Effective Date above. 
  

									
	Caribou Biosciences, Inc.	 		 	Advisor: Jennifer A. Doudna
					
	By:	 	 /s/ Rachel Haurwitz
	 		 	By:	 	 /s/ Jennifer A. Doudna

					
	Name:	 	 Rachel Haurwitz
	 		 		 	
					
	Title:	 	 President
	 		 		 	

  
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 Exhibit 10.44 

AMENDMENT NO. 1 TO SCIENTIFIC ADVISORY BOARD AGREEMENT 

This Amendment No. 1 (“Amendment No. 1”) to the Scientific Advisory Board Agreement dated
June 18, 2012 (the “Agreement”), by and between Jennifer A. Doudna (“Advisor”), an individual, and Caribou Biosciences, Inc., a Delaware corporation, having its principal place of business at 2929
7th Street Suite 120, Berkeley, CA 94710 (“Caribou”) (Advisor and Caribou collectively referred to hereinafter as the “Parties”), is entered into as
of April 12, 2014 (the “Amendment No. 1 Execution Date”). 
 WHEREAS, pursuant to the
Agreement, Advisor agreed to provide advice, counsel and Services (as defined in the Agreement) under the terms and conditions set forth in the Agreement; 

WHEREAS, at the time of the Agreement, the Parties agreed that good and valuable consideration would be exchanged; 

WHEREAS, paragraph 2(a) of the Agreement, is amended to fully clarify the Parties’ intention that Advisor receive common stock as
outlined in the Restricted Common Stock Purchase Agreement, executed July 2, 2012, in exchange for Advisor’s Services under the Agreement; 

WHEREAS, paragraph 2(a) of the Agreement, contained a clerical error stating that the Advisor receive no consideration, which was not the
intent of the Parties; 
 WHEREAS, the Parties now wish to confirm having reviewed and agreed to include an Exhibit A to the Agreement,
which reflects the consideration initially agreed to by the Parties, and having incorporated the terms and conditions thereof into the Agreement; 

NOW, THEREFORE, in exchange for good and valuable consideration, receipt of which is hereby acknowledged, the Parties agree as follows: 

 

	 	1.	 Amendment to Section 2 Fees and Expenses. Section 2(a) of the Agreement is
hereby deleted in its entirety and replaced with the following: 

  

	 	(a)	 Consideration. The Advisor shall receive the compensation as provided for in Exhibit A for the Services
rendered by Advisor as described above and the rights granted to the Company hereunder. 

  

	 	2.	 Exhibit A. The Exhibit A in Schedule I hereto is hereby incorporated into the Agreement as Exhibit A.

  

	 	3.	 Further Consideration. In further consideration for the Services and rights granted to the Company under
the Agreement and in consideration for entering into this Amendment No. 1, Company shall pay to Advisor One Hundred Dollars ($100) within thirty (30) days after the Amendment No. 1 Execution Date. 

 

	 	4.	 Advisor Acknowledgements. Advisor acknowledges and agrees that, as of the Execution Date, she has been
paid or provided all compensation, consideration, reimbursements and any other amounts or entitlements that may have been owed to her by the Company for the Services or otherwise. Advisor also acknowledges and agrees that she has fully complied with
the terms and conditions of the Agreement and shall continue to do so. 

  

	 	5.	 Independent Contractor. Nothing herein is intended to alter Advisor’s role as an independent
contractor of the Company, as set forth under Section 7(a) of the Agreement. As such, Advisor acknowledges and agrees that Advisor is obligated to report as income all compensation received pursuant to the Agreement, and acknowledges the
obligation to pay all applicable self-employment and other taxes thereon. Advisor further acknowledges that it is the intent of the Parties that neither Advisor nor any employees or contractors of Advisor, if any, receive any Company-sponsored

	 	
benefits from the Company either as a consultant or employee. Such benefits include, but are not limited to, paid vacation, sick leave, medical insurance, and 401(k) participation. If Advisor is
reclassified by a state or federal agency or court as an employee, for whatever reason, Advisor will become a reclassified employee and will receive no benefits except those mandated by state or federal law, even if by the terms of the
Company’s benefit plans in effect at the time of reclassification she would otherwise be eligible for such benefits. 

  

	 	6.	 No Other Amendments. No amendments are made other than those expressly set forth in this Amendment
No. 1, and all provisions of the Agreement unaffected by this Amendment No. 1 remain in full force and effect. In the event of a conflict between the Agreement and this Amendment No. 1, this Amendment No. 1 shall control.

  

	 	7.	 Entire Agreement. This Amendment No. 1 sets forth the entire agreement and understanding between
the Parties with respect to the amendment of the Agreement, and supersedes all previous agreements, promises, representations, understandings and negotiations, whether written or oral, between the Parties, with respect to the amendment and addition
of the same. 

  

	 	8.	 Counterparts. This Amendment No. 1 may be executed in two or more counterparts, each of which shall
constitute an original, and all of which together shall constitute a single instrument. 

  

	 	9.	 Governing Law. This Amendment No. 1 will be governed by the laws of the State of California (with
the exception of its conflict of laws provisions). 

 [Signature page follows] 

  
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 IN WITNESS WHEREOF, the Parties have executed this Amendment No. 1 as of the Amendment
No. 1 Effective Date. 
  

									
	CARIBOU BIOSCIENCES, INC.	 		 	JENNIFER A. DOUDNA.
					
	By:	 	 /s/ Rachel Haurwitz
	 		 	By:	 	 /s/ Jennifer A. Doudna

					
	Name:	 	RACHEL HAURWITZ	 		 	Name:	 	JENNIFER A. DOUDNA
					
	Title:	 	PRESIDENT AND CEO	 		 	Title:	 	SCIENTIFIC ADVISOR

  
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 SCHEDULE I to AMENDMENT NO. 1 TO 

SCIENTIFIC ADVISORY BOARD AGREEMENT 

Exhibit A 

Compensation 
 In consideration
for the Services rendered and the rights granted to Company, the Company and Advisor have entered into that certain Restricted Common Stock Purchase Agreement dated July 2, 2012 between Company and Advisor for the purchase of common stock of
Company.

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