SecProbe.io

CORRESP
 1
 filename1.htm

 CORRESP

 CARIBOU BIOSCIENCES, INC.
 2929 7th Street Suite
105 Berkeley, California 94710
 (510) 982-6030
 May 13, 2025 VIA EDGAR
 United States Securities and Exchange Commission
 Division of Corporation Finance 100 F Street, NE
 Washington, D.C. 20549 Attention: Tim Buchmiller

 Re:
 Caribou Biosciences, Inc. (the “Registrant”) - Request for Acceleration
 Registration Statement on Form S-3
 File No. 333-287093
 Ladies and Gentlemen: Pursuant to Rule 461
promulgated under the Securities Act of 1933, as amended, the Registrant hereby requests acceleration of the effective date of its Registration Statement on Form S-3 (File
 No. 333-287093) (the “Registration Statement”), so that it may become effective at 4:00 p.m. Eastern Time on Wednesday, May 14, 2025 , or as soon thereafter as
practicable. The Registrant hereby authorizes each of Ashok Mukhey and Danielle Carbone of Reed Smith LLP, attorneys for the Registrant,
to orally modify or withdraw this request for acceleration. The Registrant requests that it be notified of such effectiveness by a
telephone call to Ashok Mukhey at (310) 734-5291 or, in his absence, Danielle Carbone at (212) 549-0229.

 CARIBOU BIOSCIENCES, INC.

 By:

 /s/ Sriram Ryali

 Name: Sriram Ryali

 Title: Chief Financial Officer

<DOCUMENT>
<TYPE>TEXT-EXTRACT
<SEQUENCE>2
<FILENAME>filename2.txt
<TEXT>
 May 12, 2025

Rachel E. Haurwitz, Ph.D.
President and Chief Executive Officer
Caribou Biosciences, Inc.
2929 7th Street, Suite 105
Berkeley, California 94710

 Re: Caribou Biosciences, Inc.
 Registration Statement on Form S-3
 Filed May 8, 2025
 File No. 333-287093
Dear Rachel E. Haurwitz Ph.D.:

 This is to advise you that we have not reviewed and will not review your
registration
statement.

 Please refer to Rules 460 and 461 regarding requests for acceleration.
We remind you
that the company and its management are responsible for the accuracy and
adequacy of their
disclosures, notwithstanding any review, comments, action or absence of action
by the staff.

 Please contact Tim Buchmiller at 202-551-3635 with any questions.

 Sincerely,

 Division of
Corporation Finance
 Office of Life
Sciences
cc: Ashok W. Mukhey, Esq.
</TEXT>
</DOCUMENT>

CORRESP
1
filename1.htm

CORRESP

 CARIBOU BIOSCIENCES, INC.

2929 7th Street

 Suite
105

 Berkeley, California 94710

(510) 982-6030

August 12, 2022

 VIA EDGAR

 United States Securities and Exchange Commission

Division of Corporate Finance

 100 F Street, NE

Washington, D.C. 20549

 Attention: Margaret Schwartz

Re: Caribou Biosciences, Inc. (the “Registrant”) - Request for Acceleration

       Registration Statement on Form S-3

       File No. 333- 266712

Ladies and Gentlemen:

 Pursuant to Rule 461
promulgated under the Securities Act of 1933, as amended, the Registrant hereby requests acceleration of the effective date of its Registration Statement on Form S-3 (File
No. 333- 266712) (the “Registration Statement”), so that it may become effective at 4:00 p.m. Eastern Standard Time on Tuesday, August 16, 2022, or as soon thereafter
as practicable.

 The Registrant hereby authorizes each of Ashok Mukhey and Wendy Grasso of Reed Smith LLP, attorneys for the Registrant,
to orally modify or withdraw this request for acceleration.

 The Registrant requests that it be notified of such effectiveness by a
telephone call to Ashok Mukhey at (310) 734-5291 or, in his absence, Wendy Grasso at (212) 549-0216.

CARIBOU BIOSCIENCES, INC.

By:

 /s/ Jason O’Byrne

Name:

Jason O’Byrne

Title:

Chief Financial Officer

United States securities and exchange commission logo
August 11, 2022
Rachel E. Haurwitz, Ph.D.
President and Chief Executive Officer
Caribou Biosciences, Inc.
2929 7th Street, Suite 105
Berkeley, California 94710
Re:Caribou Biosciences, Inc.
Registration Statement on Form S-3
Filed August 9, 2022
File No. 333-266712
Dear Dr. Haurwitz:
            This is to advise you that we have not reviewed and will not review your registration
statement.
            Please refer to Rules 460 and 461 regarding requests for acceleration.  We remind you
that the company and its management are responsible for the accuracy and adequacy of their
disclosures, notwithstanding any review, comments, action or absence of action by the staff.
            Please contact Margaret Schwartz at 202-551-7153 with any questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       Ashok W. Mukhey, Esq.

CORRESP
1
filename1.htm

CORRESP

 July 20, 2021

VIA EDGAR

 United States Securities and Exchange
Commission

 Division of Corporation Finance

 100 F Street
N.E.

 Washington, D.C. 20549

 Attn: Dillon Hagius and
Irene Paik

RE:
 Caribou Biosciences, Inc. (the “Registrant”) – Request for Acceleration

 Registration Statement on Form S-1, as amended

 File No. 333-257604

Ladies and Gentlemen:

 Pursuant to Rule 461
promulgated under the Securities Act of 1933, as amended, the Registrant hereby requests acceleration of the effective date of its Registration Statement on Form S-1 (File
No. 333-257604) (the “Registration Statement”), so that it may become effective at 4:00 p.m., Eastern Standard Time on Thursday, July 22, 2021, or as soon
thereafter as practicable.

 The Registrant hereby authorizes each of Ashok Mukhey and Wendy Grasso of Reed Smith LLP, attorneys for the
Registrant, to orally modify or withdraw this request for acceleration.

 The Registrant requests that it be notified of such effectiveness
by a telephone call to Ashok Mukhey at (310) 968-5839 or, in his absence, Wendy Grasso at (917) 993-3645.

 CARIBOU BIOSCIENCES,
INC.

By:

 /s/ Rachel E. Haurwitz

Name: Rachel E. Haurwitz

Title: President and Chief Executive Officer

CORRESP
1
filename1.htm

CORRESP

 July 20, 2021

U.S. Securities and Exchange Commission

 Division of Corporation
Finance

 100 F Street, N.E.

 Washington, D.C. 20549

Attn:
 Dillon Hagius

 Irene Paik

Re:
 Caribou Biosciences, Inc.

 Registration Statement on Form S-1, as amended

 File No. 333-257604

Ladies and Gentlemen:

 In connection with the above-referenced
Registration Statement, and pursuant to Rule 461 under the Securities Act of 1933, as amended (the “Act”), we hereby join in the request of Caribou Biosciences, Inc. that the effective date of the Registration Statement be
accelerated so that it will be declared effective at 4:00 p.m., Eastern Standard Time, on Thursday, July 22, 2021, or as soon thereafter as practicable.

Pursuant to Rule 460 under the Act, please be advised that we have distributed approximately 1,150 copies of the Preliminary Prospectus dated July 19,
2021 (the “Preliminary Prospectus”) through the date hereof, to underwriters, dealers, institutions and others.

 In connection with the
Preliminary Prospectus distribution for the above-referenced issue, the prospective underwriters have confirmed that they are complying with the 48-hour requirement in Rule
15c2-8(b) under the Securities Exchange Act of 1934, as amended.

 Very truly yours,

BOFA SECURITIES, INC.

 CITIGROUP GLOBAL MARKETS INC.

SVB LEERINK LLC

 As Representatives of the several underwriters

 [Signature Pages Follow]

BOFA SECURITIES, INC.

By:

 /s/ Michele A.H. Allong

Name: Michele A.H. Allong

 Title:   Authorized Signatory

CITIGROUP GLOBAL MARKETS INC.

By:

 /s/ Dean Poniros

Name: Dean Poniros

 Title:   Director

SVB LEERINK LLC

By:

 /s/ Dan Dubin

Name: Dan Dubin, M.D.

 Title:   Vice Chairman, Global Co-Head of Investment Banking

 As representatives of the several underwriters.

cc:
 Ilir Mujalovic, Partner, Shearman & Sterling LLP

 Gina Lee, Associate, Shearman & Sterling LLP

 [Signature Page to
Acceleration Request Letter]

CORRESP
1
filename1.htm

CORRESP

 Ashok W. Mukhey

 Direct Phone: +1 310 734
5291

 Email: amukhey@reedsmith.com

 Reed Smith LLP

1901 Avenue of the Stars

 Suite
700

 Los Angeles, CA 90067-6078

 +1
310 734 5200

 Fax +1 310 734 5299

reedsmith.com

 July 12, 2021

*FOIA Confidential Treatment Request*

Confidential Treatment Requested by Caribou Biosciences, Inc.

in connection with Registration Statement on Form S-1 (File
No. 333-257604)

 VIA EDGAR

 U.S. Securities and Exchange Commission

Office of Life Sciences

Division of Corporation Finance

100 F Street, N.E.

Washington, D.C. 20549

Attention: Franklin Wyman

Jeanne Baker

 Dillon
Hagius

 Irene Paik

Re:
 Caribou Biosciences, Inc.

Registration Statement on Form S-1

Filed on July 1, 2021

File No. 333-257604

 Ladies and
Gentlemen:

 On behalf of Caribou Biosciences, Inc. (the “Company”), we submit this letter (this “Letter”)
to the staff (the “Staff”) of the Securities and Exchange Commission (the “Commission”). The Company originally filed the above-referenced Registration Statement on Form
S-1 (the “Registration Statement”) with the Commission on July 1, 2021.

 The purpose
of this Letter is to provide supplemental information to the Staff regarding the Company’s stock-based compensation to facilitate the Staff’s review of the Company’s accounting treatment. In particular, the Company references Comment
#9 of the Staff’s letter dated June 2, 2021 requesting an explanation of the reasons for any differences between the recent valuations of the Company’s common stock and the estimated offering price. The supplemental response set forth
below is based upon information provided to Reed Smith LLP by the Company.

 On behalf of the Company, we are respectfully requesting confidential
treatment for specified portions of this Letter pursuant to Rule 83 promulgated by the Commission (17 C.F.R. § 200.83). This Letter is accompanied by such request for confidential treatment because of the commercially sensitive nature of the
information discussed in this Letter. A redacted version of this Letter will be filed with the Commission on EDGAR, omitting the confidential information. The redacted information has been replaced in this Letter as filed on EDGAR with a placeholder
identified by the mark [***].

 ABU DHABI ◆ ATHENS ◆ AUSTIN ◆ BEIJING
◆ BRUSSELS ◆ CENTURY CITY ◆ CHICAGO ◆ DALLAS ◆ DUBAI ◆ FRANKFURT ◆ HONG KONG

HOUSTON ◆ KAZAKHSTAN ◆ LONDON ◆ LOS ANGELES ◆ MIAMI
◆ MUNICH ◆ NEW YORK ◆ PARIS ◆ PHILADELPHIA ◆ PITTSBURGH ◆ PRINCETON

RICHMOND ◆ SAN FRANCISCO ◆ SHANGHAI ◆ SILICON VALLEY ◆
SINGAPORE ◆ TYSONS ◆ WASHINGTON, D.C. ◆ WILMINGTON

 U.S. Securities and Exchange Commission

 July
12, 2021

 Page 2

 For the convenience of the Staff, we have recited the prior comment from the Staff in italicized type and
have followed the comment with the Company’s response.

 Management’s Discussion and Analysis of Financial Condition and Results of
Operations

 Critical Accounting Policies and Significant Judgments and Estimates

Stock-Based Compensation Expense, page 112

9.
 Once you have an estimated offering price range, please explain to us the reasons for any differences
between recent valuations of your common stock leading up to the planned offering and the midpoint of your estimated offering price range. This information will facilitate our review of your accounting for stock compensation. Please discuss with the
Staff how to submit your response.

 The Company’s discussion of its accounting for stock-based compensation is primarily
contained within the sections of the Registration Statement entitled “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Critical Accounting Policies and Significant Judgments and
Estimates—Stock-Based Compensation Expense” and “—Fair Value of Common Stock” and appears on pages 115 through 117 of the Registration Statement.

Estimated IPO Price Range

 The Company advises the Staff
that, although not yet reflected in the Registration Statement, it currently anticipates an approximate offering price range of $[***] to $[***]1 per share for the Company’s common stock (the
“Preliminary IPO Price Range”), with a midpoint of the anticipated range of approximately $[***] per share (the “Preliminary Assumed IPO Price”). The Preliminary IPO Price Range is based in part on
discussions with the Company’s Board of Directors (the “Board”) and reflects a number of factors, including the Company’s prospects, prospects for the biotechnology industry, the general condition of the securities
markets, the recent market prices of publicly-traded shares of generally comparable companies in the biotechnology industry, and input received from the Company’s “testing the waters meetings,” as well as input from BofA Securities,
Inc., Citigroup Global Markets Inc., and SVB Leerink LLC, as underwriters (collectively, the “Underwriters”) for the Company’s initial public offering (“IPO”). The Preliminary IPO Price
Range and Preliminary Assumed IPO Price do not reflect any stock split (or reverse stock split) that the Company might effect prior to the Commission’s declaration of effectiveness of the Registration Statement; however, the Company would not
expect any such stock split (or reverse stock split) to impact the Preliminary IPO Price Range in any manner other than to decrease (or increase) it in proportion to the stock split (or reverse stock split) itself. For consistency with the
Registration Statement, all data in this Letter is reflected on a pre-split basis, unless otherwise expressly noted.

1
 * Based on the forward stock split that the Company is contemplating, this translates into an approximate
post-split offering price range of $[***] to $[***] per share, with a midpoint of $[***] per share.

 FOIA Confidential
Treatment Requested by Caribou Biosciences, Inc.

 U.S. Securities and Exchange Commission

 July
12, 2021

 Page 3

 The parameters of the bona fide price range to be included in an amendment to the Registration Statement at
the time of the commencement of the Company’s road show remains under discussion between the Company and the Underwriters and will be subject to then-current market conditions, continuing discussions with the Underwriters, and material business
developments impacting the Company. In any event, the Company confirms to the Staff that the bona fide price range will comply with Item 501(b)(3) of Regulation S-K and CD&I 134.04.

Determinations of the Fair Value of Common Stock

 As
there has been no public market for the Company’s common stock to date, the estimated fair value of its common stock was determined by the Board, as of the date of each option grant, with input from management, based on the Company’s most
recent arm’s-length sales of its preferred stock and the most recent third-party valuation of its common stock, as well as the Board’s assessment of additional objective and subjective factors that
the Board believed were relevant at the time, including any significant developments since the most recent third-party valuation. The Board considered various objective and subjective factors to determine the fair value of the common stock as of
each grant date, including:

•

 valuations of the Company’s common stock performed with the assistance of third-party valuation specialists;

•

 the Company’s stage of development and business strategy, including the status of research and development
efforts, including preclinical studies and clinical trials, and the material risks related to the business and industry;

•

 the Company’s results of operations and financial position, including levels of available capital resources;

•

 the composition of, and changes to, the Company’s management team and board of directors;

•

 the valuation of publicly traded companies in the life sciences and biotechnology sectors, as well as recently
completed mergers and acquisitions of peer companies;

•

 the lack of marketability of the Company’s common stock;

•

 the prices of convertible preferred shares sold to investors in arm’s length transactions and the rights,
preferences, and privileges of the Company’s convertible preferred stock relative to those of the Company’s common stock; and

•

 the likelihood of achieving a liquidity event for the holders of the common and convertible preferred stock, such
as an initial public offering or a sale of the Company, given prevailing market conditions.

 FOIA Confidential
Treatment Requested by Caribou Biosciences, Inc.

 U.S. Securities and Exchange Commission

 July
12, 2021

 Page 4

 The third-party valuations of the Company’s common stock that the Board considered in making its
determinations were prepared in accordance with the American Institute of Certified Public Accountants Accounting and Valuation Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation (the “AICPA
Guide”), which prescribes several valuation approaches for determining the value of an enterprise, such as the market approach, the income approach, and the asset approach, and various methodologies for allocating the value of an
enterprise to its capital structure and specifically the common stock.

 In accordance with the AICPA Guide, the Company considered and/or applied the
following methods in determining and allocating the equity value across its classes and series of capital stock to determine the fair value of its common stock at each valuation date.

•

 Option Pricing Model (“OPM”). The OPM allocates a company’s equity value
among various classes and series of capital stock, taking into account the preferred stockholders’ liquidation preferences, participation rights, dividend policy, and conversion rights to determine how proceeds from a liquidity event shall be
distributed among the various classes and series of capital stock at a future date. The OPM utilizes the Black-Scholes-Merton Option Pricing Model (or “Black-Scholes”). The Black-Scholes implementation of the OPM treats the
rights of holders of various classes and series of securities (preferred stock, common stock, warrants, and options) as call options on any equity value of the Company above a series of breakpoints. The values of the breakpoints were calculated by
reviewing the liquidation preferences of preferred stock (including seniority of any series), participation rights of preferred stock (including any caps on such participation), and strike prices of warrants and options. The Company’s common
stock is modeled as a call option that gives its owner the right, but not the obligation, to buy the underlying value at a predetermined price or exercise price. In the model, the exercise price is based on the equity value at specific values or
breakpoints. In this method, each class and series of securities only has value if the funds available for distribution to shareholders exceed the value of the liquidation preferences at the time of a liquidity event for each of the more senior
securities classes in a company’s cap table. The Black-Scholes model requires a series of variables, including the equity value of the company, time to liquidity event, risk-free rate, and volatility.

Within the OPM framework, the Backsolve method for inferring the total equity value implied by a recent financing transaction involves the
construction of an allocation model that takes into account the company’s capital structure and the rights and preferences of each class of shares, and then assumes reasonable inputs for the other OPM variables (expected time to liquidity,
volatility, risk-free rate, etc.). The total equity value is then iterated in the model until the model output value for the equity class sold in a recent financing round equals the price paid in that round.

Given the Company’s common stock represents a non-marketable equity interest in a private
enterprise, the Company applied discounts to reflect the lack of marketability of its common stock on the weighted-average expected time to liquidity. This discount adjustment is commonly referred to as a discount for lack of marketability
(“DLOM”). The estimated fair value of the Company’s common stock at each valuation date reflected a discount for lack of marketability partially based on the anticipated likelihood and timing of a future liquidity event.

 FOIA Confidential
Treatment Requested by Caribou Biosciences, Inc.

 U.S. Securities and Exchange Commission

 July
12, 2021

 Page 5

•

 Probability-Weighted Expected Return Method (“PWERM”). The PWERM is a
scenario-based analysis that estimates the value per share of common stock based on the probability-weighted present value of expected future value per share for the Company’s common stock, under various possible future liquidity event
scenarios, considering the rights and preferences of each series and class of capital stock, discounted for a lack of marketability.

•

 Hybrid Method. The hybrid method combines the OPM and the PWERM. Under the hybrid method, the Company
utilized the OPM Backsolve method to determine the fair value of its common stock for certain of the PWERM scenarios (namely situations where the Company’s development path and future liquidity events were difficult to forecast) and potential
initial public offering exit events were explicitly modeled in the other PWERM scenarios. A DLOM adjustment was applied to the value derived under each scenario to account for a lack of access to an active public market.

For grants of stock awards made on dates for which there was no contemporaneous third-party valuation available to it, the Board determined the fair value of
the Company’s common stock on the date of grant based on the most recent third-party valuation report and other pertinent information available to the Board at the time of the grant.

For valuations performed on and prior to December 31, 2020, the Company utilized an OPM-based analysis, primarily
the OPM Backsolve method, to determine the estimated fair value of its common stock. For valuations performed after December 31, 2020, the Company utilized the Hybrid Method to determine the estimated fair value of its common stock, as the
Company determined that this was the most appropriate method given its stage of development and other relevant factors.

 Summary of Recent Equity
Grants

 The following table summarizes all stock option awards granted by the Company during the previous twelve months:

 Option Grant

Dates

Number of
Shares
Underlying
Stock
Options
Granted

Exercise
Price
Per
Share

Estimated
Fair
Value of
Common
Stock Per
Share on
Grant
Date

Date of Third-
Party Valuation

 October 1, 2020

61,500

$
5.19

$
[***]

April 30, 2020

 December 15, 2020

10,040

$
5.19

$
[***]

April 30, 2020

 March 30, 2021

858,682

$
7.47

$
[***]

March 2, 2021

 May 28, 2021

196,097

$
9.58

$
[***]

May 10, 2021

 June 29, 2021

297,211

$
9.58

$
[***]

May 10, 2021

 FOIA Confidential
Treatment Requested by Caribou Biosciences, Inc.

 U.S. Securities and Exchange Commission

 July
12, 2021

 Page 6

 Summary of Third-Party Valuations

The following is a summary of the third-party valuation reports for the equity grants listed above.

April 30, 2020 Valuation (Used for October 1, 2020 and December 15, 2020 Option Grants)

A third-party valuation specialist performed a contemporaneous valuation of the Company’s common stock as of April 30, 2020, which determined a fair
value of $[***] per share (the “April 2020 Valuation”). For the April 2020 Valuation, the third-party valuation specialist first determined an equity value by using (1) the market approach (subject company transaction
method) based on the Company’s Series B convertible preferred stock transaction that closed in May 2016, which had been subsequently adjusted in the Company’s previous valuations, (2) an equity valuation adjustment of [***]% selected
from a range of public peer company performance which was ap

CORRESP
1
filename1.htm

CORRESP

 Reed Smith LLP

1901 Avenue of the Stars
Suite 700
Los Angeles, CA 90067-6078

+1 310 734 5200

 Fax +1 310 734
5299

 reedsmith.com

 Ashok W. Mukhey

 Direct Phone: +1 310 734
5291
Email: amukhey@reedsmith.com

 July 1, 2021

 VIA EDGAR

 U.S. Securities and Exchange Commission

Division of Corporation Finance

100 F Street, N.E.

Washington, D.C. 20549

Attention: Franklin Wyman

                 Jeanne Baker

                 Dillon
Hagius

                  Irene
Paik

Re:
 Caribou Biosciences, Inc.

Amendment No. 1 to Draft Registration Statement on Form S-1

Confidentially submitted on June 11, 2021

CIK No. 0001619856

 Ladies and
Gentlemen:

 On behalf of our client, Caribou Biosciences, Inc., a Delaware corporation (the “Company”), we are hereby filing with
the U.S. Securities and Exchange Commission (the “Commission”) the Company’s Registration Statement on Form S-1 (the “Registration Statement”). The Company
previously submitted draft Registration Statements on Form S-1 on a confidential basis pursuant to Title I, Section 106 under the Jumpstart Our Business Startups Act (the “JOBS Act”), on
May 7, 2021 and on June 11, 2021 (“Submission No. 2”). The Registration Statement filed concurrently with this letter has been revised to reflect certain changes to Submission
No. 2, including changes intended to respond to certain comments included in the comment letter to Submission No. 2 from the staff of the Commission (the “Staff”) dated June 23, 2021. For your convenience, we
are providing by separate email a courtesy copy of the Registration Statement that has been marked to show changes from Submission No. 2, as well as copy of this letter.

For ease of review, we have set forth below the numbered comments of your letter in bold type followed by the Company’s response thereto.

June 23, 2021 Staff Comment Letter

 Prospectus
Summary

 Overview, page 1

1.
 Please revise your pipeline table so that the Phase 2 and Phase 3 trials are graphically depicted in two
different columns, or tell us the basis for your belief that you will be able to conduct Phase 2/3 trials for all your product candidates. While we note your revised disclosure in response to our prior comment 1 below the pipeline table that
“Phase 3 may not be required if Phase 2 is

 ABU DHABI ◆ ATHENS ◆ AUSTIN ◆ BEIJING
◆ BRUSSELS ◆ CENTURY CITY ◆ CHICAGO ◆ DALLAS ◆ DUBAI ◆ FRANKFURT ◆ HONG KONG

HOUSTON ◆ KAZAKHSTAN ◆ LONDON ◆ LOS ANGELES ◆ MIAMI
◆ MUNICH ◆ NEW YORK ◆ PARIS ◆ PHILADELPHIA ◆ PITTSBURGH ◆ PRINCETON

RICHMOND ◆ SAN FRANCISCO ◆ SHANGHAI ◆ SILICON VALLEY ◆
SINGAPORE ◆ TYSONS ◆ WASHINGTON, D.C. ◆ WILMINGTON

 U.S. Securities and Exchange Commission

 July 1,
2021

  Page
 2

registrational,” we believe it is overly speculative to depict these two columns as being part of the same clinical trial at this stage. To this point, we note your disclosure on page 30
that “the general approach for FDA approval of a new biologic is for the sponsor to provide dispositive data from at least two adequate and well-controlled clinical trials of the relevant biologic in the applicable patient population.”

 Response: In response to the Staff’s comment, the Company has revised the pipeline table on pages 1 and 122 so
that both Phase 2 and Phase 3 are graphically depicted in different columns.

 Strategic Agreements, page 148

2.
 We note your response to our prior comment 10 and re-issue the
comment as it relates to the AbbVie Agreement. Please revise the description of the upper range of the royalty payments to a range within ten percentage points (for example, between twenty and thirty percent).

Response: In response to the Staff’s comment, the Company has revised the description of the upper range of the royalty payments on
pages 148, F-35, and F-50 to a range within ten percentage points, expressed as the high-single-digit to low-teens percent range.

Financial Statements

 Note 2. Summary of Significant
Accounting Policies

 Revenues, page F-9

3.
 Your expanded disclosures indicate that certain of your license agreements have, for accounting purposes,
two performance obligations: a license and a material right for annual license renewal agreements. Please better describe the nature and accounting for these agreements, including whether the licenses granted represent a right to use or a right to
access; the factors considered in concluding that these two performance obligations were individually distinct; the expected contract term with all reasonably likely renewal periods; and how you determined the transaction price and allocated
revenues to each performance obligation. Clarify whether or not the annual maintenance fees referenced on pages F-23 and F-52 related to these agreements and if so, how.
Please reference the technical guidance upon which you relied.

 Response: In response to the Staff’s
comment, the Company has revised the disclosure on pages 114, F-9, F-10, F-23, and F-52 to reflect the accounting treatment of
certain of the Company’s CRISPR genome-editing intellectual property license agreements (“license agreements”) and associated annual license fees. Such license agreements require, after the first year of the agreement, payments of non-refundable annual license fees by the licensee, which are accounted for as license renewals. (In the license agreements, these non-refundable annual license fees are
referred to as “annual maintenance fees.”)

 The license agreements were not considered to be material to the Company’s
consolidated financial statements. The Company had a total of three such license agreements in 2019 and four such license agreements in 2020 (including the three license agreements from 2019) with recognized revenues of $1.1 million and
$1.2 million, respectively. No additional license agreements were entered into in the quarter ended March 31, 2021. Current and non-current deferred revenue related to these license agreements was
$1.1 million, $1.0 million, and $1.0 million as of December 31, 2019, December 31, 2020, and March 31, 2021, respectively.

 U.S. Securities and Exchange Commission

 July 1,
2021

  Page
 3

 These license agreements have two performance obligations: a license and a material right for
annual license renewals. The licenses granted by the Company under the license agreements represent licenses to functional intellectual property and grant the licensees the right to use certain CRISPR genome-editing intellectual property controlled
by the Company in designated fields. Pursuant to paragraphs ASC 606-10-55-62 and 55-63,
the Company identified two performance obligations: the delivery of the license to the functional intellectual property and the material right for the license renewals. Pursuant to ASC
606-10-55-42, the license renewals provide a separate and distinct right that a licensee would not receive without entering into
the license agreement, as the license renewals are priced at a discount that is incremental to the range of discounts typically given for such licenses.

In accordance with ASC
606-10-25-23 through 25-30, the Company concluded that the performance obligations
related to the licenses to functional intellectual property are satisfied when a licensee is able to use, and benefit from, the license for the first year. At the end of the first year, and on an annual basis thereafter, the licensee is required to
pay annual license fees in order to retain the license. The Company concluded that the performance obligation underlying the material right for each license renewal is satisfied at the point in time the annual license fee is paid by the licensee and
the renewal period begins.

 Furthermore, as the license renewal options are for the same license to the functional intellectual property as
was the initial one-year term, pursuant to ASC 606-10-55-45, the Company applied the
practical alternative to estimating the stand-alone selling price of the license renewals, by reference to the total expected consideration, which is the aggregate of the first-year upfront license fee and the annual license fees for the expected
renewals. The total transaction price for each of these license agreements was allocated under the alternative approach for estimating the stand-alone selling price of the licenses. The Company estimated the expected contract term with all
reasonably likely renewal periods to be the remaining life of the licensed intellectual property.

 In light of the relatively small impact
of these four license agreements on the Company’s consolidated financial statements, the Company respectfully submits that its revised disclosures are sufficient to provide material information to investors relating to the revenue recognition
under these license agreements.

 U.S. Securities and Exchange Commission

 July 1,
2021

  Page
 4

 We hope the foregoing answers are responsive to your comments. Please do not hesitate to contact me by
telephone at (310) 734-5291 or by email to amukhey@reedsmith.com (or Wendy Grasso by telephone at (212) 549-0216 or by email to wgrasso@reedsmith.com) with any questions
or comments regarding this correspondence.

Very truly yours,

/s/ Ashok W. Mukhey

Ashok W. Mukhey

For Reed Smith LLP

 AWM:cc

cc:
 Rachel E. Haurwitz, Ph.D., Caribou Biosciences, Inc.

Barbara G. McClung, J.D., Caribou Biosciences, Inc.

Wendy A. Grasso, Reed Smith LLP

Ilir Mujalovic, Shearman & Sterling LLP

United States securities and exchange commission logo
June 23, 2021
Rachel Haurwitz, Ph.D.
President and Chief Executive Officer
Caribou Biosciences, Inc.
2929 7th Street, Suite 105
Berkeley, California 94710
Re:Caribou Biosciences, Inc.
Amendment No. 1 to Draft Registration Statement on Form S-1
Submitted June 11, 2021
CIK No. 0001619856
Dear Dr. Haurwitz:
            We have reviewed your amended draft registration statement and have the following
comments.  In some of our comments, we may ask you to provide us with information so we
may better understand your disclosure.
            Please respond to this letter by providing the requested information and either submitting
an amended draft registration statement or publicly filing your registration statement on
EDGAR.  If you do not believe our comments apply to your facts and circumstances or do not
believe an amendment is appropriate, please tell us why in your response.
            After reviewing the information you provide in response to these comments and your
amended draft registration statement or filed registration statement, we may have additional
comments.
Draft Registration Statement on Form S-1 - Amendment No. 1
Prospectus Summary
Overview, page 1
1.Please revise your pipeline table so that the Phase 2 and Phase 3 trials are graphically
depicted in two different columns, or tell us the basis for your belief that you will be able
to conduct Phase 2/3 trials for all your product candidates.  While we note your revised
disclosure in response to our prior comment 1 below the pipeline table that "Phase 3 may
not be required if Phase 2 is registrational," we believe it is overly speculative to depict
these two columns as being part of the same clinical trial at this stage.  To this point, we
note your disclosure on page 30 that "the general approach for FDA approval of a new

 FirstName LastNameRachel  Haurwitz, Ph.D.
 Comapany NameCaribou Biosciences, Inc.
 June 23, 2021 Page 2
 FirstName LastName
Rachel  Haurwitz, Ph.D.
Caribou Biosciences, Inc.
June 23, 2021
Page 2
biologic is for the sponsor to provide dispositive data from at least two adequate and well-
controlled clinical trials of the relevant biologic in the applicable patient population."
Strategic Agreements, page 149
2.We note your response to our prior comment 10 and re-issue the comment as it relates to
the AbbVie Agreement.  Please revise the description of the upper range of the royalty
payments to a range within ten percentage points (for example, between twenty and thirty
percent).
Financial Statements
Note 2. Summary of Significant Accounting Policies
Revenues, page F-9
3.Your expanded disclosures indicate that certain of the your license agreements have, for
accounting purposes, two performance obligations: a license and a material right for
annual license renewal agreements.  Please better describe the nature and accounting for
these agreements, including whether the licenses granted represent a right to use or a right
to access; the factors considered in concluding that these two performance obligations
were individually distinct; the expected contract term with all reasonably likely renewal
periods; and how you determined the transaction price and allocated revenues to each
performance obligation.  Clarify whether or not the annual maintenance fees referenced
on pages F-23 and F-52 related to these agreements and if so, how.  Please reference the
technical guidance upon which you relied.
            You may contact Franklin Wyman at 202-551-3660 or Jeanne Baker at 202-551-3691 if
you have questions regarding comments on the financial statements and related matters. Please
contact Dillon Hagius at 202-551-7967 or Irene Paik at 202-551-6553 with any other questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       Ashok Mukhey

United States securities and exchange commission logo
June 2, 2021
Rachel Haurwitz, Ph.D.
President and Chief Executive Officer
Caribou Biosciences, Inc.
2929 7th Street, Suite 105
Berkeley, California 94710
Re:Caribou Biosciences, Inc.
Draft Registration Statement on Form S-1
Submitted May 7, 2021
CIK No. 0001619856
Dear Dr. Haurwitz:
            We have reviewed your draft registration statement and have the following comments.  In
some of our comments, we may ask you to provide us with information so we may better
understand your disclosure.
            Please respond to this letter by providing the requested information and either submitting
an amended draft registration statement or publicly filing your registration statement on
EDGAR.  If you do not believe our comments apply to your facts and circumstances or do not
believe an amendment is appropriate, please tell us why in your response.
            After reviewing the information you provide in response to these comments and your
amended draft registration statement or filed registration statement, we may have additional
comments.
Draft Registration Statement on Form S-1
Prospectus Summary
Overview, page 1
1.Your statements that your allogeneic CAR-T cell therapies have "best-in-class" potential
imply the likelihood of regulatory approval and comparisons to other products and
product candidates. The statements are speculative in light of their regulatory status.
Please remove the "best-in-class" references.
2.Please make the following changes to your pipeline table:
•Include all clinical stages that must be completed before commercialization (i.e., add
columns for Phases 2 and 3).
•We note the table entitled "Programs under AbbVie collaboration" with

 FirstName LastNameRachel  Haurwitz, Ph.D.
 Comapany NameCaribou Biosciences, Inc.
 June 2, 2021 Page 2
 FirstName LastNameRachel  Haurwitz, Ph.D.
Caribou Biosciences, Inc.
June 2, 2021
Page 2
"undisclosed" targets that are only discussed briefly in your description of your
collaboration and license agreement with AbbVie. To the extent these are material
programs, disclose the targets and provide descriptions of these programs. Otherwise,
please remove them from the table or explain the basis for your belief that they are
material and should be included in your pipeline table.
•Please explain what is involved in "lead optimization" and why you believe this is a
separate and distinct development phase, as opposed to part of the discovery
phases. While we will consider your response, we do not currently believe that
the lead optimization is distinct from the discovery phase and should thus be depicted
under the discovery column.  A textual discussion of the program is likely a more
appropriate place to make distinctions regarding different segments within a
particular phase.
3.We note your disclosure here and throughout the filing that you are focused on advancing
treatments for "clinically validated targets."  Please balance these statements throughout
your registration statement with the disclosure on page 22 that no products that use novel
genome-editing technologies have advanced into clinical trials or received marketing
approval in the United States.
4.You note on page 2 and throughout your filing that the February 2021 collaboration
with AbbVie is " is an external validation of our chRDNA genome-editing technology."
Please revise this statement and similar statements on pages 98 and 116 to remove the
"external validation" language, as efficacy determinations are the exclusive purview of the
FDA or other regulators.
5.Please balance your disclosure on page 2 and throughout your filing that "CB-010 is
currently being evaluated in a phase 1 clinical trial in patients with relapsed or refractory
B cell non-Hodgkin lymphoma" with the fact that you have not yet enrolled patients in
this trial.  We note your disclosure to this effect on page 26.
Risk Factors
Our rights to develop and commercialize our product candidates are subject..., page 57
6.Please provide additional risk factor disclosure about the dispute with Intellia
Therapeutics.  Specifically, disclose whether your inability to reach a "final resolution"
with Intellia would hinder your ongoing Phase 1 trial of CB-010 and whether you would
be able to continue clinical development of CB-010 if this dispute is not resolved.
Industry and Market Data, page 88
7.We note your statements regarding market data used in the prospectus, including that the
sources of the information do not guarantee the accuracy or completeness of the
information and that investors are cautioned "not to give undue weight" to estimates.
Please revise these statements to eliminate any implication that investors are not entitled
to rely on the information included in your registration statement.

 FirstName LastNameRachel  Haurwitz, Ph.D.
 Comapany NameCaribou Biosciences, Inc.
 June 2, 2021 Page 3
 FirstName LastNameRachel  Haurwitz, Ph.D.
Caribou Biosciences, Inc.
June 2, 2021
Page 3
Results of Operations
Licensing and Collaboration Revenue, page 104
8.Please describe and quantify for us revenue by license and collaboration agreement for
each period presented that includes reference to related information in Note 4. In addition,
clarify whether the "Private Company" is a related party, as referenced on page F-8, or an
unaffiliated company, as referenced on page F-21. Revise your disclosure accordingly.
Management's Discussion and Analysis of Financial Condition and Results of Operations
Critical Accounting Policies and Significant Judgments and Estimates
Stock-Based Compensation Expense, page 112
9.Once you have an estimated offering price range, please explain to us the reasons for any
differences between recent valuations of your common stock leading up to the planned
offering and the midpoint of your estimated offering price range. This information will
facilitate our review of your accounting for stock compensation. Please discuss with the
Staff how to submit your response.
Business
Strategic Agreements, page 143
10.Please revise the descriptions of your strategic agreements as appropriate to revise any
references to "low-double-digit" and "mid-double-digit" royalties to a royalty range within
ten percentage points (for example, between twenty and thirty percent) and to disclose
the expected expiry of the last-to-expire patent licensed under the agreements.
11.With respect to the Collaboration and License Agreement with AbbVie, please disclose
the fee that AbbVie must pay to expand from two Program Slots and the maximum
aggregate commercial milestones you may receive under the agreement.
12.With respect to your Exclusive License Agreement with MSKCC, please revise your
disclosure to clarify whether the IPO would trigger a success payment.
13.Please expand your discussion of the ProMab Agreement to disclose the upfront payment,
royalty term, and termination provisions.
14.With respect to the Pioneer Agreement, please disclose the "certain events" that permit
either party to terminate the agreement.
Intellectual Property, page 147
15.Please expand your intellectual property discussion to disclose the number and type of
patents that cover each of your product candidates and programs, whether they are owned
or licensed, the related jurisdiction, and the expiration year.

 FirstName LastNameRachel  Haurwitz, Ph.D.
 Comapany NameCaribou Biosciences, Inc.
 June 2, 2021 Page 4
 FirstName LastNameRachel  Haurwitz, Ph.D.
Caribou Biosciences, Inc.
June 2, 2021
Page 4
Legal Proceedings
Intellia Arbitration, page 167
16.Please disclose, if known, a general timeframe for when you expect to negotiate economic
terms based on the revised scope of the leaseback and whether you believe that agreeing
to these terms will resolve the conflict underlying the Intellia Arbitration.  If not, please
expand your disclosure to discuss how the interim award determining that the two patent
families are included in the Intellia License Agreement impacts any licenses or
sublicenses that you have granted, if at all.
Licensing Agreement Transaction, page 193
17.You disclose that you have a license agreement with a  "private company" controlled by
Anterra that provides for milestone payments and royalty payments for future sales of
licensed products.  Please disclose the material terms of the license agreement, including
the milestone payments and the royalty range, and file the agreement as an exhibit or tell
us why you believe such filing is not required.  Refer to Item 601(b)(10) of Regulation S-
K.
Principal Stockholders, page 197
18.Please identify in footnotes to the table all natural persons who have voting and/or
investment power over the shares held by F-Prime Capital Partners.
Financial Statements
Note 2. Summary of Significant Accounting Policies
Revenues, page F-9
19.Please expand your disclosures to describe the nature of your performance
obligation associated with maintenance fees and when you satisfy your performance
obligation.  In this regard, while you disclose herein that you recognize revenues
associated with annual maintenance fees on a point in time basis on each anniversary date,
you also disclose on page F-23 that your deferred revenue primarily results from customer
payments received upfront for maintenance fees because these performance obligations
are satisfied over time.  Please address this apparent discrepancy.  Refer to your disclosure
on page 111 as well.
General
20.Please supplementally provide us with copies of all written communications, as defined in
Rule 405 under the Securities Act, that you, or anyone authorized to do so on your behalf,
present to potential investors in reliance on Section 5(d) of the Securities Act, whether or
not they retain copies of the communications.

 FirstName LastNameRachel  Haurwitz, Ph.D.
 Comapany NameCaribou Biosciences, Inc.
 June 2, 2021 Page 5
 FirstName LastName
Rachel  Haurwitz, Ph.D.
Caribou Biosciences, Inc.
June 2, 2021
Page 5

            You may contact Franklin Wyman at 202-551-3660 or Jeanne Baker at 202-551-3691 if
you have questions regarding comments on the financial statements and related matters.  Please
contact Dillon Hagius at 202-551-7967 or Irene Paik at 202-551-6553 with any other questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       Ashok Mukhey