SecProbe.io

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 1
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 TECTONIC THERAPEUTIC, INC.
 490 Arsenal Way, Suite 210
 Watertown, MA 02472 (339) 666-3320 July 11, 2025
 Via EDGAR U.S. Securities and Exchange
Commission Division of Corporation Finance Office of
Information Technologies and Services 100 F Street, N.E.
 Washington, D.C. 20549

 Re:
 Tectonic Therapeutic, Inc.
 Registration Statement on Form S-3
 File No. 333-288539
 Ladies and Gentlemen: In accordance with Rule 461 under the
Securities Act of 1933, as amended, the undersigned registrant (the “ Registrant ”) hereby requests that the U.S. Securities and Exchange Commission (the “ Commission ”) take appropriate action to cause
the Registration Statement on Form S-3 (File No. 333-288539) (the “ Registration Statement ”) to become effective on Tuesday, July 15,
2025, at 4:00 p.m., Eastern Time, or as soon as practicable thereafter, or at such later time as the Registrant may orally request via telephone call to the staff of the Commission (the “ Staff ”). The Registrant hereby
authorizes Brandon Fenn of Cooley LLP, counsel to the Registrant, to make such request on its behalf. Once the Registration Statement has been declared
effective, please orally confirm that event with Brandon Fenn of Cooley LLP, counsel to the Registrant, at (212) 479-6626, or in his absence Minkyu Park of Cooley LLP at (212)
 479-6588. Very truly yours,

 TECTONIC THERAPEUTIC, INC.

 By:

 /s/ Daniel Lochner

 Name:

 Daniel Lochner

 Title:

 Chief Financial Officer

 cc:
 Brandon Fenn, Cooley LLP
 Minkyu Park, Cooley LLP

<DOCUMENT>
<TYPE>TEXT-EXTRACT
<SEQUENCE>2
<FILENAME>filename2.txt
<TEXT>
 July 10, 2025

Daniel Lochner
Chief Financial Officer
Tectonic Therapeutic, Inc.
490 Arsenal Way
Suite 210
Watertown, MA 02472

 Re: Tectonic Therapeutic, Inc.
 Registration Statement on Form S-3
 Filed July 7, 2025
 File No. 333-288539
Dear Daniel Lochner:

 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 Jessica Dickerson at 202-551-8013 with any questions.

 Sincerely,

 Division of
Corporation Finance
 Office of Life
Sciences
cc: Brandon Fenn, Esq.
</TEXT>
</DOCUMENT>

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 TECTONIC THERAPEUTIC, INC.
 490 Arsenal Way, Suite 210
 Watertown, MA 02472 (339) 666-3320 March 31, 2025
 Via EDGAR U.S. Securities and Exchange
Commission Division of Corporation Finance Office of
Information Technologies and Services 100 F Street, N.E.
 Washington, D.C. 20549

 Re :
 Tectonic Therapeutic, Inc.
 Registration Statement on Form S-1
 File No. 333-286133
 Ladies and Gentlemen: In accordance with Rule 461 under the
Securities Act of 1933, as amended, the undersigned registrant (the “ Registrant ”) hereby requests that the U.S. Securities and Exchange Commission (the “ Commission ”) take appropriate action to cause
the Registration Statement on Form S-1 (File No. 333-286133) (the “ Registration Statement ”) to become effective on Wednesday, April 2, 2025, at 4:00 p.m., Eastern
Time, or as soon as practicable thereafter, or at such later time as the Registrant may orally request via telephone call to the staff of the Commission (the “ Staff ”). The Registrant hereby authorizes Brandon Fenn of Cooley
LLP, counsel to the Registrant, to make such request on its behalf. Once the Registration Statement has been declared effective, please orally confirm
that event with Brandon Fenn of Cooley LLP, counsel to the Registrant, at (212) 479 6626, or in his absence Minkyu Park of Cooley LLP at (212) 479 6588.
 Very truly yours,

 TECTONIC THERAPEUTIC, INC.

 By:

 /s/ Daniel Lochner

 Name:

 Daniel Lochner

 Title:

 Chief Financial Officer

 cc:
 Brandon Fenn, Cooley LLP
 Minkyu Park, Cooley LLP

<DOCUMENT>
<TYPE>TEXT-EXTRACT
<SEQUENCE>2
<FILENAME>filename2.txt
<TEXT>
 March 31, 2025

Daniel Lochner
Chief Financial Officer
Tectonic Therapeutic, Inc.
490 Arsenal Way
Suite 210
Watertown, MA 02472

 Re: Tectonic Therapeutic, Inc.
 Registration Statement on Form S-1
 Filed March 26, 2025
 File No. 333-286133
Dear Daniel Lochner:

 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 Jessica Dickerson at 202-551-8013 with any questions.

 Sincerely,

 Division of
Corporation Finance
 Office of Life
Sciences
cc: Brandon Fenn, Esq.
</TEXT>
</DOCUMENT>

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 TECTONIC THERAPEUTIC, INC.

490 Arsenal Way, Suite 210

Watertown, MA 02472

 (339) 666-3320

 July 26, 2024

Via EDGAR

 U.S. Securities and Exchange Commission

 Division of Corporation Finance

 Office of Information
Technologies and Services

 100 F Street, N.E.

 Washington,
D.C. 20549

Re:
 Tectonic Therapeutic, Inc.

Registration Statement on Form S-1

File No. 333-280909

Ladies and Gentlemen:

 In accordance with Rule 461 under the
Securities Act of 1933, as amended, the undersigned registrant (the “Registrant”) hereby requests that the U.S. Securities and Exchange Commission (the “Commission”) take appropriate action to cause
the Registration Statement on Form S-1 (File No. 333-280909) (the “Registration Statement”) to become effective on Tuesday, July 30,
2024, at 4:00 p.m., Eastern Time, or as soon as practicable thereafter, or at such later time as the Registrant may orally request via telephone call to the staff of the Commission (the “Staff”). The Registrant hereby
authorizes Courtney T. Thorne of Cooley LLP, counsel to the Registrant, to make such request on its behalf.

 Once the Registration Statement has been
declared effective, please orally confirm that event with Courtney T. Thorne of Cooley LLP, counsel to the Registrant, at (617) 937-2318, or in her absence Katherine Denby of Cooley LLP at (202) 776-2070.

 Very truly yours,

TECTONIC THERAPEUTIC, INC.

By:

 /s/ Daniel Lochner

Name:

Daniel Lochner

Title:

Chief Financial Officer

cc:
 Courtney T. Thorne, Cooley LLP

Katherine Denby, Cooley LLP

July 26, 2024
Daniel Lochner
Chief Financial Officer
Tectonic Therapeutic, Inc.
490 Arsenal Way
Suite 210
Watertown, MA 02472
Re:Tectonic Therapeutic, Inc.
Registration Statement on Form S-1
Filed July 19, 2024
File No. 333-280909
Dear Daniel Lochner:
            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 Tyler Howes at 202-551-3370 with any questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:Courtney T. Thorne, Esq.

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 AVROBIO, Inc.

One Broadway

 14th Floor

 Cambridge, MA 02142

May 2, 2024

 Via EDGAR Transmission

United States Securities and Exchange Commission

 Division of
Corporation Finance

 Office of Life Sciences

 100 F Street,
N.E.

 Washington, D.C. 20549-3628

 Attention: Jenn Do, Mary
Mast, Lauren Hamill and Chris Edwards

Re:
 AVROBIO, Inc.

Acceleration Request for Registration Statement on Form S-4

File No. 333-277048

Ladies and Gentlemen:

 Pursuant to Rule 461 under the
Securities Act of 1933, as amended (the “Act”), AVROBIO, Inc. (the “Company”) hereby requests that the effective date of the above-referenced registration statement (the “Registration Statement”) be
accelerated to May 3, 2024, at 4:15 p.m., Eastern Time, or as soon thereafter as practicable, unless we or our outside counsel, Goodwin Procter LLP, request by telephone that such Registration Statement be declared effective at some other time.
In making this acceleration request, the Company acknowledges that it is aware of its responsibilities under the Act.

 Once the Registration Statement is
effective, please orally confirm the event with our outside counsel, Goodwin Procter LLP, by calling Adam V. Johnson at (212) 459-7072. We also respectfully request that a copy of the written order from the
Securities and Exchange Commission verifying the effective time and date of the Registration Statement be sent to our counsel, Goodwin Procter LLP, Attention: Adam V. Johnson, by email to AdamJohnson@goodwinlaw.com or by facsimile to (212) 320-0632.

 If you have any questions regarding this request, please contact Adam V. Johnson of Goodwin Procter LLP at
(212) 459-7072.

Sincerely,

AVROBIO, INC.

/s/ Erik Ostrowski

Erik Ostrowski

President, Interim Chief Executive Officer, Chief Financial

Officer and Treasurer

 cc:   Steven Avruch, AVROBIO, Inc.

Mitchell Bloom, Esq., Goodwin Procter LLP

Robert Masella, Esq., Goodwin Procter LLP

James Ding, Esq., Goodwin Procter LLP

Adam V. Johnson, Esq., Goodwin Procter LLP

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 Goodwin Procter LLP

 100 Northern Avenue

Boston, Massachusetts 02210

 VIA EDGAR

April 29, 2024

 United States Securities and Exchange
Commission

 Division of Corporation Finance

 Office of Life
Sciences

 100 F Street, N.E.

 Washington, D.C. 20549-3628

 Attention: Jenn Do, Mary Mast, Lauren Hamill and Chris Edwards

Re:
 AVROBIO, Inc.

Amendment No. 2 to the Registration Statement on Form S-4

Filed April 15, 2024

File No. 333-277048

 Ladies and
Gentlemen,

 On behalf of AVROBIO, Inc. (the “Company”), we are submitting this letter to the Securities and Exchange Commission (the
“SEC”) via EDGAR in response to the comment letter from the staff of the SEC (the “Staff”), dated April 24, 2024 (the “Comment Letter”), pertaining to the Company’s above-referenced
Amendment No. 2 Registration Statement on Form S-4 (the “Amendment No. 2”). In connection with such responses, the Company is concurrently filing Amendment No. 3
to the Registration Statement (the “Amendment No. 3”).

 For your convenience, the Staff’s comments have been
reproduced in bold and italics herein with responses immediately following each comment. Unless otherwise indicated, page references in the reproductions of the Staff’s comments refer to the Amendment No. 2, and page references in the
responses below refer to the Amendment No. 3. Capitalized terms used in this letter but otherwise not defined herein shall have the meanings set forth in the Amendment No. 3.

Amendment No. 2 to Registration Statement on Form S-4

Risk Factors

 Tectonic currently relies and
expects to rely in the future on the use of manufacturing suites in third-party facilities..., page 146

1.
 We note that Tectonic currently relies on WuXi Biologics (Hong Kong) Limited as the sole
manufacturer of its supply of TX45 product candidate used in its clinical trials. Please tell us your consideration of whether the proposed BIOSECURE Act, if passed and enacted into law, may impact the combined company’s business and
operations, and if so, how. Include risk factor disclosure as appropriate.

 U.S. Securities and Exchange Commission

Division of Corporation Finance

 Office of Life Sciences

April 29, 2024

 Page 2

 
 Response: The BIOSECURE Act (“Act”) was introduced on January 25, 2024 by
the Chairman and Ranking Member of the Select Committee on the Strategic Competition Between the United States and the Chinese Communist Party (“Select Committee”). The Act was subsequently referred to the House of
Representatives Committee on Oversight and Accountability for further action because under its establishing resolution, the Select Committee does not “have legislative jurisdiction and shall have no authority to take legislative action on any
bill or resolution.” To date, the Committee on Oversight and Accountability has not taken any action to review or report the Act for consideration by the House of Representatives. Thus, it is highly uncertain with the remaining
legislative days before the 118th Congress adjourns, that the Act will be passed by the House of Representatives, the Senate, or be signed into law by the President. A substantively similar version of the Act was introduced in the Senate in December
2023 and was voted out of the Senate Committee on Homeland Security & Governmental Affairs on March 6, 2024.

Moreover, if the Act were to be signed into law in its present form, its impacts on biotechnology companies like Tectonic are not
certain. For example, the Act mentions WuXi Apptec, but does not mention WuXi Biologics, making it unclear if WuXi Biologics is covered by the Act’s restriction. Some members of Congress have mentioned WuXi Biologics as a subsidiary
of WuXi AppTec in letters to various government agencies, thus suggesting that WuXi Biologics could be covered under the Act. The first part of the Act’s definition of “Biotechnology Companies of Concern” lists four specific entities
and any “subsidiary, parent affiliate, or successor of such entities.” Included in this list of entities is WuXi AppTech (not WuXi Biologics); and WuXi Biologics has stated it is not a subsidiary of WuXi AppTec, so to Tectonic’s
knowledge this part of the definition would not apply. The second part of the definition of “Biotechnology Companies of Concern” lists a number of factors which reflect a risk to national security, none of which to Tectonic’s
knowledge are applicable to, nor has there been any official public determination that they are applicable to, WuXi Biologics. In addition, as currently drafted, the Act only targets U.S. federal government contracts, grants, and funding provided to
designated “Biotechnology Companies of Concern,” or to entities procuring services and/or equipment from such companies. The Act does not prohibit or restrict private-sector transactions or dealings with WuXi Apptec or the other named
“Biotechnology Companies of Concern.” As such, Tectonic does not believe that the Act, if passed in its current form, would prohibit the combined company from continuing its relationship with WuXi Biologics. Tectonic also does not
currently have any U.S. federal government contracts, grants, or funding.

 In addition, the Senate version of the Act includes a
grandfathering provision, which exempts the prohibitions of the Act in cases in which equipment or services are produced or provided by a “Biotechnology Company of Concern” under a contract or agreement entered into prior to the effective
date of the Act. Tectonic’s manufacturing agreement with WuXi Biologics has been in place since 2022.

 Tectonic will continue to
closely monitor and evaluate the potential impacts of the Act on its business and operations. At this time, Tectonic has sufficient supply of the TX45 product candidate in hand and in storage to meet its current clinical trial needs. Tectonic is
currently evaluating and developing steps to mitigate risk to ensure supply of the TX45 product candidate, including evaluating alternate supply chain arrangements.

The Company also advises the Staff that it has revised its disclosure on pages 132 and 147 of the Amendment No. 3.

 U.S. Securities and Exchange Commission

Division of Corporation Finance

 Office of Life Sciences

April 29, 2024

 Page 3

 The Merger

Background of the Merger, page 179

2.
 We note your response to prior comment 5. Your description of the background of the Merger
Agreement is still not sufficient to clearly explain the bases for all material terms of the Merger agreement that were negotiated through proposals and counter-proposals. Please further revise this section to explain the reason(s) why the various
parties proposed and counter-proposed valuations for AVROBIO and Tectonic. Specifically:

•

 Clearly explain the material bases for the proposed valuations for AVROBIO. In this regard, you explain
that proposed valuation amounts “includ[e] a targeted $65 million of net cash at closing,” but you do not explain the reason(s) for proposed valuations in excess of the targeted net cash amount. To the
extent that the parties ascribed value to AVROBIO in excess of its targeted ending net cash position based on AVROBIO’s public company listing or for any other material reason, please so state.

•

 Explain the basis for the proposed valuations for Tectonic. In this regard, we note that the reason(s) why
Tectonic proposed an initial valuation for Tectonic of $150 million in the Tectonic November 11, 2023 Proposal are unclear. It is similarly unclear why AVROBIO countered with a
proposed valuation for Tectonic of $130 million on November 15, 2023 at the direction of the Transaction Committee, and why the parties ultimately agreed to the
$140 million valuation for Tectonic proposed in the Tectonic November 21, 2023 proposal.

Response: The Company respectfully acknowledges the Staff’s comment and advises the Staff that it has revised the disclosure on
pages 189-192 of the Amendment No. 3.

 *****

Please contact the undersigned at (212) 459-7072 or via email at AdamJohnson@goodwinlaw.com if you have any questions
with respect to the foregoing.

Very truly yours,

 /s/ Adam V. Johnson

Adam V. Johnson

Goodwin Procter LLP

cc:
 Erik Ostrowski, AVROBIO, Inc.

Mitchell Bloom, Goodwin Procter LLP

Robert Masella, Goodwin Procter LLP

James Ding, Goodwin Procter LLP

Marc A. Recht, Cooley LLP

Miguel J. Vega, Cooley LLP

Courtney T. Thorne, Cooley LLP

Michael Rohr, Cooley LLP

United States securities and exchange commission logo
April 24, 2024
Erik Ostrowski
Interim Chief Executive Officer
AVROBIO, Inc.
100 Technology Square
Sixth Floor
Cambridge, MA 02139
Re:AVROBIO, Inc.
Amendment No. 2 to Registration Statement on Form S-4
Filed April 15, 2024
File No. 333-277048
Dear Erik Ostrowski:
            We have reviewed your amended registration statement and have the following
comments.
            Please respond to this letter by amending your registration statement and providing the
requested information. If you do not believe a comment applies to your facts and circumstances
or do not believe an amendment is appropriate, please tell us why in your response.
            After reviewing any amendment to your registration statement and the information you
provide in response to this letter, we may have additional comments. Unless we note otherwise,
any references to prior comments are to comments in our April 8, 2024 letter.
Amendment No. 2 to Registration Statement on Form S-4
Risk Factors
Tectonic currently relies and expects to rely in the future on the use of manufacturing suites in
third-party facilities..., page 146
1.We note that Tectonic currently relies on WuXi Biologics (Hong Kong) Limited as the
sole manufacturer of its supply of TX45 product candidate used in its clinical trials. Please
tell us your consideration of whether the proposed BIOSECURE Act, if passed and
enacted into law, may impact the combined company’s business and operations, and if so,
how. Include risk factor disclosure as appropriate.
The Merger
Background of the Merger, page 179

 FirstName LastNameErik Ostrowski
 Comapany NameAVROBIO, Inc.
 April 24, 2024 Page 2
 FirstName LastName
Erik Ostrowski
AVROBIO, Inc.
April 24, 2024
Page 2
2.We note your response to prior comment 5. Your description of the background of the
Merger Agreement is still not sufficient to clearly explain the bases for all material terms
of the Merger agreement that were negotiated through proposals and counter-proposals.
Please further revise this section to explain the reason(s) why the various parties proposed
and counter-proposed valuations for AVROBIO and Tectonic.  Specifically:
•Clearly explain the material bases for the proposed valuations for AVROBIO. In this
regard, you explain that proposed valuation amounts "includ[e] a targeted $65 million
of net cash at closing," but you do not explain the reason(s) for proposed valuations
in excess of the targeted net cash amount. To the extent that the parties ascribed value
to AVROBIO in excess of its targeted ending net cash position based on
AVROBIO's public company listing or for any other material reason, please so state.
•Explain the basis for the proposed valuations for Tectonic.  In this regard, we note
that the reason(s) why Tectonic proposed an initial valuation for Tectonic of $150
million in the Tectonic November 11, 2023 Proposal are unclear. It is similarly
unclear why AVROBIO countered with a proposed valuation for Tectonic of $130
million on November 15, 2023 at the direction of the Transaction Committee, and
why the parties ultimately agreed to the $140 million valuation for Tectonic proposed
in the Tectonic November 21, 2023 proposal.
            Please contact Jenn Do at 202-551-3743 or Mary Mast at 202-551-3613 if you have
questions regarding comments on the financial statements and related matters. Please contact
Lauren Hamill at 303-844-1008 or Chris Edwards at 202-551-6761 with any other questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       Adam Johnson

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 Goodwin Procter LLP

 100 Northern
Avenue

Boston, Massachusetts 02210

 VIA EDGAR

April 15, 2024

 United States Securities and Exchange
Commission

 Division of Corporation Finance

 Office of Life
Sciences

 100 F Street, N.E.

 Washington, D.C. 20549-3628

 Attention: Jenn Do, Mary Mast, Lauren Hamill and Chris Edwards

Re:
 AVROBIO, Inc.

Amendment No. 1 to the Registration Statement on Form S-4

Filed March 26, 2024

File No. 333-277048

 Ladies and
Gentlemen,

 On behalf of AVROBIO, Inc. (the “Company”), we are submitting this letter to the Securities and Exchange Commission (the
“SEC”) via EDGAR in response to the comment letter from the staff of the SEC (the “Staff”), dated April 8, 2024 (the “Comment Letter”), pertaining to the Company’s above-referenced
Amendment No. 1 Registration Statement on Form S-4 (the “Amendment No. 1”). In connection with such responses, the Company is concurrently filing Amendment No. 2
to the Registration Statement (the “Amendment No. 2”).

 For your convenience, the Staff’s comments have been
reproduced in bold and italics herein with responses immediately following each comment. Unless otherwise indicated, page references in the reproductions of the Staff’s comments refer to the Amendment No. 1, and page references in the
responses below refer to the Amendment No. 2. Capitalized terms used in this letter but otherwise not defined herein shall have the meanings set forth in the Amendment No. 2.

Amendment No. 1 to Registration Statement on Form S-4 filed March 26, 2024

Cover Page

1.
 Given that the Nasdaq listing condition is waivable, please further revise your disclosure to
indicate whether recirculation or resolicitation of shareholders will occur prior to the vote if the listing application is not approved but the condition is waived.

Response: The Company respectfully acknowledges the Staff’s comment and advises the Staff that it has revised the disclosure on the
cover page and pages 8, 33 and 234-235 of the Amendment No. 2.

 U.S. Securities and Exchange Commission

Division of Corporation Finance

 Office of Life Sciences

April 15, 2024

  Page
 2

 What are the private financings?, page 2

2.
 We note your response to prior comment 2, and your revised disclosure on page 3 and elsewhere
throughout that the closing of the merger is conditioned upon the satisfaction or waiver of the receipt of cash proceeds not less than $114.5 million in connection with the consummation of the
transactions contemplated by the private financings. As this closing condition is waivable, we reissue prior comment 2 in part. Please revise this Q&A, the summary risks and risk factors, and elsewhere as appropriate to discuss risks and
uncertainties if stockholders are asked to make voting decisions without knowing whether the private financings will close in timely manner, or at all, and if they do not close, whether the minimum cash proceeds condition will be waived. Discuss the
combined company’s liquidity position and related risks in the event that the merger closes without the $114.5 million from the private financings in place.

Response: The Company respectfully acknowledges the Staff’s comment and advises the Staff that it has revised the disclosure on
pages 3, 29, 37-39 and 265 of the Amendment No. 2. The Company respectfully further advises the Staff that, in the event that all or any portion of the private financings fails to close in a timely manner, the Company intends to evaluate all
options at such time (including whether or not to agree to any waiver of the minimum private financing condition), taking into account the circumstances relating to such failure, potentially including (without limitation) the respective amounts of
the private financings that are and are not able to be closed in a timely manner and the respective identities of those relevant investors, the evaluation and intentions of Tectonic and the Tectonic Board, the resulting cash runway for the combined
company that would be associated with such a partial closing of the private financings, the legal options of each of the Company and Tectonic with respect to the non-closing investors, and any other
circumstances that each of the AVROBIO Board and Tectonic Board then deem relevant.

 Tectonic, page 15

3.
 We note your response to prior comment 28, which we reissue in part with respect to your
revisions. In light of your disclosure on page 353 that Tectonic is in the early stages of using the GEODe platform to discover biologic drugs, please revise conclusory statements such as the following on pages 15 and 351, qualifying them as
appropriate to indicate if such statements are currently aspirational or management’s beliefs:

•

 “These modifications have resulted in the ability to identify improved molecules.”

•

 ...the Tectonic team continues to evolve and modify aspects of the platform for even better
results.”

 Response: The Company respectfully acknowledges the Staff’s comment and advises the
Staff that it has revised the disclosure on pages 16 and 358 of the Amendment No. 2.

 U.S. Securities and Exchange Commission

Division of Corporation Finance

 Office of Life Sciences

April 15, 2024

  Page
 3

 Interests of AVROBIO’s Directors and Executive Officers in the Merger, page 22

4.
 We note your response to prior comment 10, which we reissue. As referenced in your response
letter, the definition of “Aspen Net Cash” in the Merger Agreement will provide for certain exclusions from the calculation of net cash at the determination time, including but not limited to certain payments to AVROBIO’s executives
such as the unpaid cash cost of any change in control payments, severance payments, bonus payments or retention payments payable. Please revise this section and elsewhere as appropriate to disclose the types and aggregate amounts of any material
payments to be excluded from net cash and explain the impact of such exclusion to other AVROBIO stockholders. In this regard, we note that disclosures throughout indicate (1) that under certain
circumstances, the ownership percentages in the combined company may be adjusted up or down including, but not limited to, if AVROBIO’s net cash at closing is lower than $64.5 million or greater
than $65.5 million, (2) that AVROBIO management currently anticipates AVROBIO’s net cash as of closing will be approximately
$65.0 million to $75.0 million, and (3) the currently estimated ownership percentages are based on an
assumption of $65.0 million in AVROBIO’s net cash as of closing. Given that you now disclose on page 22 that executive officers may receive cash severance payments with an aggregate collective
value of approximately $2.8 million, revise if true to state whether excluding such severance payments to executives from net cash at closing could result in a downward adjustment to AVROBIO
shareholders’ equity allocation post-merger. Alternatively, tell us why the exclusion of approximately $2.8 million from the calculation of net cash at the determination time should not be
considered material.

 Response: The Company respectfully acknowledges the Staff’s comment and
advises the Staff that it has revised the disclosure on pages 22-23 of the Amendment No. 2.

 The Merger

Background of the Merger, page 175

5.
 We note your response to prior comment 22, which we reissue in part. Your description of the
background of the Merger Agreement should be sufficient to explain how the material terms of the Merger Agreement were negotiated through proposals and counter-proposals, including which party proposed initial terms, which party requested revised
terms, and the bases for doing so. Please further revise this section to explain how the parties came to agree upon the following material economic terms included in the final Merger Agreement:

•

 the valuations of the parties, including the additional $12.5 million
ascribed by Tectonic to AVROBIO in excess of its ending net cash position;

•

 the equity allocations in the combined company via the Exchange Ratio contemplated in the Merger Agreement;
and

•

 the concurrent private financings with Tectonic.

Response: The Company respectfully acknowledges the Staff’s comment and advises the Staff that it has revised the responsive
disclosure regarding the negotiation of such material economic terms on pages 189-191, 193-195 and 204 and additional responsive disclosure is already included on pages 189-192, 195 and 204 of the Amendment No. 2.

 U.S. Securities and Exchange Commission

Division of Corporation Finance

 Office of Life Sciences

April 15, 2024

  Page
 4

 Opinion of Houlihan Lokey to the AVROBIO Board

Material Financial Analyses, page 208

6.
 We note your response to prior comment 24, which we reissue with respect to the second bullet. For
each of the analyses discussed, please clarify what value(s) were used to calculate the implied value for Tectonic post-merger, and why. For example, disclose whether Houlihan Lokey use the mean, median, high or low value, or some other value from
the calculations of the comparable companies/transactions.

 Response: The Company respectfully
acknowledges the Staff’s comment and advises the Staff that it has revised the disclosure on pages 213-220 of the Amendment No. 2.

Material U.S. Federal Income Tax Consequences of the Merger, page 225

7.
 We note your response to comment 6 and we re-issue the
comment. Mergers or exchange transactions where the Company represents that the transaction is tax-free, generally involve material tax consequences and a tax opinion should be provided. We note that holders
of Tectonic will be receiving registered shares of AVROBIO in connection with the merger, which will result in material tax consequences to such investors. Please revise to file an opinion of counsel with respect to the material tax consequences of
the merger. Please refer to Section III of Staff Legal Bulletin 19.

 Response: The Company
respectfully acknowledges the Staff’s comment and advises the Staff that it has revised the disclosure on pages 12-13, 42, 232-233 and 476 of the Amendment No. 2 and filed tax opinions of counsel as Exhibit 8.1 and Exhibit 8.2 with
Amendment No. 2.

 AVROBIO’s Management’s Discussion and Analysis of Financial Condition and Results of Operations, page 390

 Components of AVROBIO’s Consolidated Results of Operations, page 392

8.
 We have read your response to comment 46. Please revise your disclosures accordingly to
specifically address the reason(s) for the 25% increase in R&D expenses for the Gaucher program and the 33% increase in the Hunter program during 2023, given especially the explanation for the consolidated decreases on page 395 and that the
comprehensive review resulting in your intention to halt development of your programs occurred in July 2023. In addressing this comment, we note certain information you have provided in response to comment 52 may be relevant.

 Response: The Company respectfully acknowledges the Staff’s comment and advises the Staff that it has
revised the disclosure on page 400 of the Amendment No. 2.

 U.S. Securities and Exchange Commission

Division of Corporation Finance

 Office of Life Sciences

April 15, 2024

  Page
 5

 Tectonics Notes to the Consolidated Financial Statements

3. Fair Value Measurements

 Safe Liabilities,
page F-47

9.
 You state that as of December 31, 2023 you
determined the probabilities of the occurrence of an equity financing, public listing transaction and dissolution used were 87.5%, 10.0%, and 2.5%, respectively, which appears to differ from your disclosure in the beginning of the second paragraph
of “Valuation of SAFE Liabilities” on page 417. Please revise for consistency throughout the filing, as applicable.

Response: The Company respectfully acknowledges the Staff’s comment and, following oral guidance from the Staff on April 11,
2024, advises the Staff that it has clarified the disclosure on page 424 and F-48 of the Amendment No. 2 and will not make additional changes to Amendment No. 2 in response to this comment.

General

10.
 We acknowledge the information provided in your response to prior comment 52. We do not concur
with the analysis and conclusion set forth in your response letter. We note your disclosure on pages 49, 177, and elsewhere indicating that AVROBIO (1) sold its cystinosis gene therapy program to
Novartis in June 2023, (2) halted further development of its remaining gene therapy programs in July 2023 to explore the availability of one or more strategic transactions involving AVROBIO and/or any of its businesses or assets, and
(3) in September 2023, terminated its agreements with the University of Manchester for the license and development of a gene therapy for MPSII (Hunter syndrome) and discontinued AVR-RD-05, a Hunter syndrome gene therapy program. We further note that if the merger is completed, (i) the business of the
combined company will be focused on the development of Tectonic’s product candidates, and (ii) that AVROBIO’s pre-closing assets will be subject to a
CVR Agreement providing that AVROBIO will use commercially reasonable efforts during the 18-month period following the closing to effect dispositions of AVROBIO’s
pre-closing assets to a third party that has delivered inbound interest. Please refer to footnote 943 of the Special Purpose Acquisition Companies, Shell Companies, and Projection adopting release (Release
Nos. 33-11265; 34-99418; IC-35096), available at
https://www.sec.gov/files/rules/final/2024/33-11265.pdf.

Response: The Company respectfully acknowledges the Staff’s comment and advises the Staff that it has revised the disclosure on
pages 167-168 and 453 of the Amendment No. 2.

11.
 We note your disclosure that Tectonic stockholders owning approximately 88% of the Tectonic
outstanding capital stock have entered into a voting agreement whereby such stockholders have agreed to vote in favor of the Merger and that such stockholders will execute a written consent providing for such approval following the effectiveness of
this S-4 registration statement. Please confirm that, with respect to Tectonic stockholders, both (1) the voting support agreement was entered into only by
executive officers, directors, affiliates and holders of 5% or more of Teutonic’s voting equity securities, and (2) that Tectonic will solicit votes from stockholders who have not signed the
agreements and would be ineligible to purchase in a private offering. Refer to Securities Act Sections Compliance and Disclosure Interpretations 239.13.

 U.S. Securities and Exchange Commission

Division of Corporation Finance

 Office of Life Sciences

April 15, 2024

  Page
 6

 Response: The Company respectfully acknowledges the Staff’s comment and advises
the Staff that the voting and support agreements were entered into only by: (i) Tectonic executive officers and their family members or affiliates; (ii) Tectonic directors and their family members or affiliates; (iii) affiliates of
Tectonic; and (iv) holders of 5% or more of the voting equity securities of Tectonic. Tectonic later intends to solicit consents pursuant to the consent solicitation and information statement from all Tectonic stockholders, including Tectonic
stockholders who did not sign the voting agreement and who would be ineligible to purchase in a private offering pursuant to a valid exemption from registration.

*****

 Please contact the undersigned at (212) 459-7072 or via email at AdamJohnson@goodwinlaw.com if you have any questions with respect to the foregoing.

Very truly yours,

 /s/ Adam V. Johnson

Adam V. Johnson

Goodwin Procter LLP

cc:
 Erik Ostrowski, AVROBIO, Inc.

Mitchell Bloom, Goodwin Procter LLP

Robert Masella, Goodwin Procter LLP

James Ding, Goodwin Procter LLP

Marc A. Recht, Cooley LLP

Miguel J. Vega, Cooley LLP

Courtney T. Thorne, Cooley LLP

Michael Rohr, Cooley LLP

United States securities and exchange commission logo
April 8, 2024
Erik Ostrowski
Interim Chief Executive Officer
AVROBIO, Inc.
100 Technology Square
Sixth Floor
Cambridge, MA 02139
Re:AVROBIO, Inc.
Amendment No. 1 to Registration Statement on Form S-4
Filed March 25, 2024
File No. 333-277048
Dear Erik Ostrowski:
            We have reviewed your amended registration statement and have the following
comments.
            Please respond to this letter by amending your registration statement and providing the
requested information. If you do not believe a comment applies to your facts and circumstances
or do not believe an amendment is appropriate, please tell us why in your response.
            After reviewing any amendment to your registration statement and the information you
provide in response to this letter, we may have additional comments. Unless we note otherwise,
any references to prior comments are to comments in our March 12, 2024 letter.
Amendment No. 1 to Registration Statement on Form S-4 filed March 26, 2024
Cover Page
1.Given that the Nasdaq listing condition is waivable, please further revise your disclosure
to indicate whether recirculation or resolicitation of shareholders will occur prior to the
vote if the listing application is not approved but the condition is waived.
What are the private financings?, page 2
2.We note your response to prior comment 2, and your revised disclosure on page 3 and
elsewhere throughout that the closing of the merger is conditioned upon the satisfaction or
waiver of the receipt of cash proceeds not less than $114.5 million in connection with the
consummation of the transactions contemplated by the private financings. As this closing
condition is waivable, we reissue prior comment 2 in part. Please revise this Q&A, the

 FirstName LastNameErik Ostrowski
 Comapany NameAVROBIO, Inc.
 April 8, 2024 Page 2
 FirstName LastName
Erik Ostrowski
AVROBIO, Inc.
April 8, 2024
Page 2
summary risks and risk factors, and elsewhere as appropriate to discuss risks and
uncertainties if stockholders are asked to make voting decisions without knowing whether
the private financings will close in timely manner, or at all, and if they do not close,
whether the minimum cash proceeds condition will be waived. Discuss the combined
company’s liquidity position and related risks in the event that the merger closes without
the $114.5 million from the private financings in place.
Tectonic, page 15
3.We note your response to prior comment 28, which we reissue in part with respect to your
revisions.  In light of your disclosure on page 353 that Tectonic is in the early stages of
using the GEODe platform to discover biologic drugs, please revise conclusory statements
such as the following on pages 15 and 351, qualifying them as appropriate to indicate if
such statements are currently aspirational or management's beliefs:
•"These modifications have resulted in the ability to identify improved molecules."
•...the Tectonic team continues to evolve and modify aspects of the platform for even
better results."

Interests of AVROBIO's Directors and Executive Officers in the Merger, page 22
4.We note your response to prior comment 10, which we reissue. As referenced in
your response letter, the definition of “Aspen Net Cash” in the Merger Agreement will
provide for certain exclusions from the calculation of net cash at the determination time,
including but not limited to certain payments to AVROBIO’s executives such as the
unpaid cash cost of any change in control payments, severance payments, bonus payments
or retention payments payable. Please revise this section and elsewhere as appropriate to
disclose the types and aggregate amounts of any material payments to be excluded from
net cash and explain the impact of such exclusion to other AVROBIO stockholders. In this
regard, we note that disclosures throughout indicate (1) that under certain circumstances,
the ownership percentages in the combined company may be adjusted up or down
including, but not limited to, if AVROBIO’s net cash at closing is lower than
$64.5 million or greater than $65.5 million, (2) that AVROBIO management currently
anticipates AVROBIO’s net cash as of closing will be approximately $65.0 million to
$75.0 million, and (3) the currently estimated ownership percentages are based on an
assumption of $65.0 million in AVROBIO’s net cash as of closing. Given that you now
disclose on page 22 that executive officers may receive cash severance payments with an
aggregate collective value of approximately $2.8 million, revise if true to state whether
excluding such severance payments to executives from net cash at closing could result in a
downward adjustment to AVROBIO shareholders' equity allocation post-merger.
Alternatively, tell us why the exclusion of approximately $2.8 million from the calculation
of net cash at the determination time should not be considered material.

 FirstName LastNameErik Ostrowski
 Comapany NameAVROBIO, Inc.
 April 8, 2024 Page 3
 FirstName LastName
Erik Ostrowski
AVROBIO, Inc.
April 8, 2024
Page 3
The Merger
Background of the Merger, page 175
5.We note your response to prior comment 22, which we reissue in part. Your description of
the background of the Merger Agreement should be sufficient to explain how the material
terms of the Merger Agreement were negotiated through proposals and counter-proposals,
including which party proposed initial terms, which party requested revised terms, and the
bases for doing so. Please further revise this section to explain how the parties came to
agree upon the following material economic terms included in the final Merger
Agreement:
•the valuations of the parties, including the additional $12.5 million ascribed by
Tectonic to AVROBIO in excess of its ending net cash position;
•the equity allocations in the combined company via the Exchange Ratio contemplated
in the Merger Agreement; and
•the concurrent private financings with Tectonic.
Opinion of Houlihan Lokey to the AVROBIO Board
Material Financial Analyses, page 208
6.We note your response to prior comment 24, which we reissue with respect to the second
bullet. For each of the analyses discussed, please clarify what value(s) were used to
calculate the implied value for Tectonic post-merger, and why. For example, disclose
whether Houlihan Lokey use the mean, median, high or low value, or some other value
from the calculations of the comparable companies/transactions.
Material U.S. Federal Income Tax Consequences of the Merger, page 225
7.We note your response to comment 6 and we re-issue the comment. Mergers or exchange
transactions where the Company represents that the transaction is tax-free, generally
involve material tax consequences and a tax opinion should be provided. We note that
holders of Tectonic will be receiving registered shares of AVROBIO in connection with
the merger, which will result in material tax consequences to such investors. Please revise
to file an opinion of counsel with respect to the material tax consequences of the merger.
Please refer to Section III of Staff Legal Bulletin 19.
AVROBIO's Management's Discussion and Analysis of Financial Condition and Results of
Operations, page 390
Components of AVROBIO's Consolidated Results of Operations, page 392
8.We have read your response to comment 46. Please revise your disclosures accordingly to
specifically address the reason(s) for the 25% increase in R&D expenses for the Gaucher
program and the 33% increase in the Hunter program during 2023, given especially the
explanation for the consolidated decreases on page 395 and that the comprehensive review
resulting in your intention to halt development of your programs occurred in July 2023. In
addressing this comment, we note certain information you have provided in response to

 FirstName LastNameErik Ostrowski
 Comapany NameAVROBIO, Inc.
 April 8, 2024 Page 4
 FirstName LastNameErik Ostrowski
AVROBIO, Inc.
April 8, 2024
Page 4
comment 52 may be relevant.
Tectonics Notes to the Consolidated Financial Statements
3. Fair Value Measurements
Safe Liabilities, page F-47
9.You state that as of December 31, 2023 you determined the probabilities of the occurrence
of an equity financing, public listing transaction and dissolution used were 87.5%, 10.0%,
and 2.5%, respectively, which appears to differ from your disclosure in the beginning of
the second paragraph of "Valuation of SAFE Liabilities" on page 417. Please revise for
consistency throughout the filing, as applicable.
General
10.We acknowledge the information provided in your response to prior comment 52. We do
not concur with the analysis and conclusion set forth in your response letter.  We
note your disclosure on pages 49, 177, and elsewhere indicating that AVROBIO (1) sold
its cystinosis gene therapy program to Novartis in June 2023, (2) halted further
development of its remaining gene therapy programs in July 2023 to explore the
availability of one or more strategic transactions involving AVROBIO and/or any of its
businesses or assets, and (3) in September 2023, terminated its agreements with the
University of Manchester for the license and development of a gene therapy for MPSII
(Hunter syndrome) and discontinued AVR-RD-05, a Hunter syndrome gene therapy
program. We further note that if the merger is completed, (i) the business of the combined
company will be focused on the development of Tectonic’s product candidates, and (ii)
that AVROBIO's pre-closing assets will be subject to a CVR Agreement providing that
AVROBIO will use commercially reasonable efforts during the 18-month period
following the closing to effect dispositions of AVROBIO’s pre-closing assets to a third
party that has delivered inbound interest. Please refer to footnote 943 of the Special
Purpose Acquisition Companies, Shell Companies, and Projection adopting release
(Release Nos. 33-11265; 34-99418; IC-35096), available at
https://www.sec.gov/files/rules/final/2024/33-11265.pdf.
11.We note your disclosure that Tectonic stockholders owning approximately 88% of the
Tectonic outstanding capital stock have entered into a voting agreement whereby such
stockholders have agreed to vote in favor of the Merger and that such stockholders will
execute a written consent providing for such approval following the effectiveness of this
S-4 registration statement.  Please confirm that, with respect to Tectonic stockholders,
both (1) the voting support agreement was entered into only by executive officers,
directors, affiliates and holders of 5% or more of Tectonic’s voting equity securities, and
(2) that Tectonic will solicit votes from stockholders who have not signed the agreements
and would be ineligible to purchase in a private offering. Refer to Securities Act Sections
Compliance and Disclosure Interpretations 239.13.
            Please contact Jenn Do at 202-551-3743 or Mary Mast at 202-551-3613 if you have

 FirstName LastNameErik Ostrowski
 Comapany NameAVROBIO, Inc.
 April 8, 2024 Page 5
 FirstName LastName
Erik Ostrowski
AVROBIO, Inc.
April 8, 2024
Page 5
questions regarding comments on the financial statements and related matters. Please contact
Lauren Hamill at 303-844-1008 or Chris Edwards at 202-551-6761 with any other questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       Adam Johnson

CORRESP
1
filename1.htm

CORRESP

 Goodwin Procter LLP

 100 Northern Avenue

Boston, Massachusetts 02210

 VIA EDGAR

 March
25, 2024

 United States Securities and Exchange Commission

Division of Corporation Finance

 Office of Life Sciences

100 F Street, N.E.

 Washington, D.C. 20549-3628

Attention: Jenn Do, Mary Mast, Lauren Hamill and Chris Edwards

Re:
 AVROBIO, Inc.

Registration Statement on Form S-4

Filed February 14, 2024

File No. 333-277048

 Ladies and
Gentlemen,

 On behalf of AVROBIO, Inc. (the “Company”), we are submitting this letter to the Securities and Exchange Commission (the
“SEC”) via EDGAR in response to the comment letter from the staff of the SEC (the “Staff”), dated March 12, 2024 (the “Comment Letter”), pertaining to the Company’s above-referenced
Registration Statement on Form S-4 (the “Registration Statement”). In connection with such responses, the Company is concurrently filing Amendment No. 1 to the Registration Statement (the
“Amended Registration Statement”).

 For your convenience, the Staff’s comments have been reproduced in bold and italics herein with
responses immediately following each comment. Unless otherwise indicated, page references in the reproductions of the Staff’s comments refer to the Registration Statement, and page references in the responses below refer to the Amended
Registration Statement. Capitalized terms used in this letter but otherwise not defined herein shall have the meanings set forth in the Amended Registration Statement.

Registration Statement on Form S-4 Filed February 14, 2024

Cover Page

1.
 It appears that the shares to be sold in the Tectonic pre-closing
private financings are included in the shares to be registered in this registration statement. The investors in the Tectonic pre-closing financing made their investment decision in a private offering and,
therefore, the sale must close privately. Please remove the Tectonic pre-closing financing shares from the registration statement.

Response: The Company respectfully acknowledges the Staff’s comment and advises the Staff that it has revised the filing fee table
filed as Exhibit 107 to the Amended Registration Statement.

 What are the private financings?, page 2

2.
 Please revise this Q&A, the summary risks and risk factors, and elsewhere as appropriate to highlight
that the closing of the merger is not conditioned upon the closing of the Tectonic private financings in the anticipated aggregate amount of $130.7 million. We note your disclosure to this effect on page 27. Discuss
risks and uncertainties if stockholders are asked to make voting decisions without knowing whether the private financings will close in timely manner, or at all. Discuss the combined company’s liquidity position and related risks in the event
that the merger closes without the private financings in place.

 Response: The Company respectfully
acknowledges the Staff’s comment and advises the Staff that it has revised the disclosure on the cover page and pages 3, 29, 36-37, 228, 234, 259, 327, 391 and 406 of the Amended Registration Statement.

 U.S. Securities and Exchange Commission

Division of Corporation Finance

 Office of Life Sciences

March 25, 2024

  Page
 2

 Why are the two companies proposing to merge?, page 2

3.
 Please revise your disclosure to clarify the combined company’s plans with respect to AVROBIO’s
legacy business. In this regard, we note your disclosure on page 13 and elsewhere throughout that on July 12, 2023, AVROBIO halted development of its clinical and research programs to explore strategic alternatives which may include, but are not
limited to, a divestiture of its legacy business.

 Response: The Company respectfully acknowledges the
Staff’s comment and advises the Staff that, while it is true that it is anticipated that the combined company will not continue to develop the Company’s legacy product candidates, as reflected in the Amended Registration Statement,
Tectonic believes it may have potential uses for certain of the Company’s intellectual property, which it may explore in the future. For example, the Company’s platform uses a proprietary lentiviral-based gene therapy approach for
autologous transduction of human hematopoietic stem cells. Tectonic believes it could potentially use this lentiviral-based technology combined with antibodies/nanobodies discovered using Tectonic’s GEODE platform to develop CAR-T cell
therapies targeting cells overexpressing GPCRs. In addition, Tectonic may choose in the future to further explore the modulation of immune responses in autoimmune diseases using the Company’s proprietary technology. During the 18-month period
following the closing, pursuant to the terms of the CVR Agreement, the combined company will use commercially reasonable efforts (as defined in the CVR Agreement) to effect dispositions of the Company’s pre-closing assets to a third party that
has delivered inbound interest (as defined in the CVR Agreement) with respect to such assets.

 What are contingent value rights (CVRs)?, page 5

4.
 We note that you disclose here and elsewhere that AVROBIO stockholders of record “as of immediately
prior to the effective time” will receive one non-transferable CVR for each outstanding share of AVROBIO common stock held by such stockholder on such date. However, disclosure following the first bullet
on page 190 states that a record date will be agreed to by AVROBIO and Tectonic prior to the effective time, and disclosure on page 237 states that the record date for the CVR distribution will be the “close of business on the business day
immediately prior to the day on which the effective time occurs.” Please revise throughout to reconcile your disclosures and clarify the record date for the issuance of CVRs to AVROBIO stockholders.

Response: The Company respectfully acknowledges the Staff’s comment and advises the Staff that it has revised the disclosure on
pages 20, 195 and 244 of the Amended Registration Statement.

 Will the common stock of the combined company trade on an exchange?, page 7

5.
 You disclose that
AVROBIO intends to file an initial listing
application for the combined company’s common stock with Nasdaq and that it is expected that such common
stock will trade on the exchange. We also
note Section 6.10 of the Merger Agreement
provides that the approval of the listing of the additional shares of AVROBIO’s common stock on Nasdaq shall have been conditionally approved prior to the Effective
Time.

•

 Please revise the Letter to Stockholders, Q&A, and elsewhere throughout as appropriate to clarify that
the closing of the merger is conditioned upon Nasdaq’s approval of the listing application.

•

 Disclose whether this condition is waivable and if so, by which party or parties.

•

 Indicate whether or not Nasdaq’s determination will be known at the time that stockholders are asked
to vote to approve the merger.

•

 Please also include a cross-reference to risk factor disclosure stating that the potential reverse stock
split may not result in an increase in the combined company’s stock price necessary to satisfy Nasdaq’s initial or continued listing requirements for the combined company.

Response: The Company respectfully acknowledges the Staff’s comment and advises the Staff that it has revised the disclosure on the
cover page and pages 7, 33 and 228 of the Amended Registration Statement. The Company further advises the Staff that Nasdaq has not yet made a determination with respect to the approval of the listing of the additional shares of AVROBIO common stock
on Nasdaq, and such approval may not be known at the time that AVROBIO stockholders are asked to vote to approve the merger. Additionally, the Company advises the Staff that this condition to the closing of the merger is waivable but only to the
extent permitted by law and only with the written waiver of each of the Company, Tectonic and Merger Sub.

 U.S. Securities and Exchange Commission

Division of Corporation Finance

 Office of Life Sciences

March 25, 2024

  Page
 3

 What are the material U.S. federal income tax consequences of the merger to U.S. Holders of Tectonic
common stock?, page 11

6.
 We note your representation here and beginning on page 219 that the parties “intend” the merger
to qualify as a reorganization within the meaning of Section 368(a) of the U.S. Internal Revenue Code of 1986, as amended (the “Code”). Please revise your disclosure here and throughout, including the
sections addressing the tax consequences of the CVRs, to provide counsel’s firm opinion for each material tax consequence, including whether the merger will qualify as a reorganization, or to explain why such opinion cannot be given. If the
opinion is subject to uncertainty, please: (1) provide an opinion that reflects the degree of uncertainty (e.g., “should” or “more likely than not”) and explains the facts or circumstances giving
rise to the uncertainty; and (2) provide disclosure of the possible alternative tax consequences including risk factor and/or other appropriate disclosure setting forth the risks of uncertain tax
treatment to investors. Also, please file the tax opinion as an exhibit to the registration statement. Please refer to Item 601(b)(8) of Regulation S-K and Section III.A. of Staff Legal Bulletin 19, Legality
and Tax Opinions in Registered Offerings.

 Response: The Company respectfully acknowledges the
Staff’s comment and advises the Staff that, because the AVROBIO stockholders are not exchanging their shares in the merger, the U.S. federal income tax consequences of the merger are not material to the Company or its shareholders. Regardless
of whether the merger qualifies as a reorganization within the meaning of Section 368(a) of the Code, it will not be a taxable transaction to the AVROBIO stockholders.

Whether or not the merger qualifies as a “reorganization” within the meaning of Section 368(a) of the Code will not impact the
AVROBIO stockholders’ decision to approve or not approve the merger or to purchase or sell the Company’s shares (or, following the consummation of the merger, shares of the combined company). Existing AVROBIO stockholders will not exchange
their shares for shares in any other entity, but will simply retain their existing shares in the Company.

 The only parties affected by the
qualification of the merger as a “reorganization” under Section 368(a) of the Code are Tectonic stockholders. However, the Amended Registration Statement is not soliciting the consent of the Tectonic stockholders to the transactions,
and such stockholders are not voting at the Company’s special meeting. Rather, promptly after the Amended Registration Statement is declared effective under the Securities Act, Tectonic will disseminate to Tectonic stockholders an information
statement that includes a material description of the merger, the Merger Agreement and related ancillary documents and appraisal rights available under Delaware law, for purposes of soliciting such Tectonic stockholders’ consent to adopt the
Merger Agreement and approve the merger. The information statement also will contain information with respect to the qualification of the merger as a “reorganization” within the meaning of Section 368(a) of the Code. In connection
with their consideration of the transaction, and based on their review of the information statement, the Merger Agreement and the ancillary agreements, the Tectonic stockholders can seek advice from their own tax advisors and will be responsible for
paying their own taxes, if any, that result from the merger. The Company and its stockholders are not required to indemnify Tectonic stockholders for such taxes, if any.

Due to substantial uncertainty as to the tax treatment of the receipt of the CVRs and the lack of authority addressing such tax treatment,
Goodwin Procter LLP and Cooley LLP, the tax counsels for the Company and Tectonic, respectively, cannot express an opinion on the tax consequences of the receipt of the CVRs. The tax disclosure in the Amended Registration Statement has been revised
on pages 12 and 264 to highlight this uncertainty and the fact that opinions cannot be provided.

 Prospectus Summary

The Companies

 AVROBIO, page 13

7.
 With reference to your disclosure on pages 13 and 17, please revise the Summary and the Q&A to
highlight, if true, that if the merger is completed, the combined company will focus on developing Tectonic’s product candidates, and it is anticipated that the combined company will not continue to develop AVROBIO’s legacy product
candidates. Also, revise the Q&A on page 5 to provide context for the discussion of the CVRs.

Response: The Company respectfully acknowledges the Staff’s comment and advises the Staff that it has revised the disclosure on
pages 2, 6-7 and 14 of the Amended Registration Statement. The Company further advises the Staff that while it is true that it is anticipated that the combined company will not continue to develop the Company’s legacy product candidates, as
reflected in the Amended Registration Statement, Tectonic believes it may have potential uses for certain of

 U.S. Securities and Exchange Commission

Division of Corporation Finance

 Office of Life Sciences

March 25, 2024

  Page
 4

the Company’s intellectual property. The Company’s platform uses a proprietary lentiviral-based gene therapy approach for autologous transduction of human hematopoietic stem cells.
Tectonic believes it could potentially use this lentiviral-based technology combined with antibodies/nanobodies discovered using Tectonic’s GEODE platform to develop CAR-T cell therapies targeting cells
overexpressing GPCRs. In addition, Tectonic may choose in the future to further explore the modulation of immune responses in autoimmune diseases using the Company’s proprietary technology.

Tectonic, page 14

8.
 Please revise the Summary and Tectonic’s Business section to provide context and balance to the
discussion of Tectonic’s proprietary technology platform, GEODe. To the extent you highlight the capabilities of the platform and Tectonic’s belief that it can “overcome the existing challenges of GPCR-targeted drug discovery”
when engineering product candidates, please also explain that Tectonic has limited experience in therapeutic discovery and development and that the platform may never result in the regulatory approval of a product candidate.

 Response: The Company respectfully acknowledges the Staff’s comment and advises the Staff that it has
revised the disclosure on pages 16 and 352 of the Amended Registration Statement. The Company further advises the Staff that the Company has added a risk factor on page 110 of the Amended Registration Statement in response to the Staff’s
comment.

 Interests of AVROBIO’s Directors and Executive Officers in the Merger, page 20

9.
 Here and in the parallel sections of the registration statement regarding the interests of
Tectonic’s directors and executive officers in the merger, please revise to quantify the value of the interests of such parties. For example only, please disclose on an aggregate basis:

•

 the value of options to purchase AVROBIO common stock that will be subject to accelerated vesting, and the
value of RSUs that will be subject to accelerated vesting and settlement into shares of AVROBIO common stock, including any necessary assumptions; and

•

 the amount of additional cash payments or “golden parachute” compensation to be received in
connection with the merger due to change in control agreements, employment contract terminations, consulting fees, etc.

Response: The Company respectfully acknowledges the Staff’s comment and advises the Staff that it has revised the disclosure on
pages 22-23 and 217 of the Amended Registration Statement.

10.
 Here and elsewhere as appropriate, please revise to explain whether any material payments to
AVROBIO’s executives, such as “golden parachute” compensation that

United States securities and exchange commission logo
March 12, 2024
Erik Ostrowski
Interim Chief Executive Officer
AVROBIO, Inc.
100 Technology Square
Sixth Floor
Cambridge, MA 02139
Re:AVROBIO, Inc.
Registration Statement on Form S-4
Filed February 14, 2024
File No. 333-277048
Dear Erik Ostrowski:
            We have reviewed your registration statement and have the following comments.
            Please respond to this letter by amending your registration statement and providing the
requested information. If you do not believe a comment applies to your facts and circumstances
or do not believe an amendment is appropriate, please tell us why in your response.
            After reviewing any amendment to your registration statement and the information you
provide in response to this letter, we may have additional comments.
Registration Statement on Form S-4 Filed February 14, 2024
Cover Page
1.It appears that the shares to be sold in the Tectonic pre-closing private financings are
included in the shares to be registered in this registration statement. The investors in the
Tectonic pre-closing financing made their investment decision in a private offering and,
therefore, the sale must close privately. Please remove the Tectonic pre-closing financing
shares from the registration statement.

What are the private financings?, page 2
2.Please revise this Q&A, the summary risks and risk factors, and elsewhere as appropriate
to highlight that the closing of the merger is not conditioned upon the closing of the
Tectonic private financings in the anticipated aggregate amount of $130.7 million.  We
note your disclosure to this effect on page 27. Discuss risks and uncertainties if

 FirstName LastNameErik Ostrowski
 Comapany NameAVROBIO, Inc.
 March 12, 2024 Page 2
 FirstName LastNameErik Ostrowski
AVROBIO, Inc.
March 12, 2024
Page 2
stockholders are asked to make voting decisions without knowing whether the private
financings will close in timely manner, or at all.  Discuss the combined company’s
liquidity position and related risks in the event that the merger closes without the private
financings in place.
Why are the two companies proposing to merge?, page 2
3.Please revise your disclosure to clarify the combined company's plans with respect to
AVROBIO's legacy business. In this regard, we note your disclosure on page 13 and
elsewhere throughout that on July 12, 2023, AVROBIO halted development of its clinical
and research programs to explore strategic alternatives which may include, but are not
limited to, a divestiture of its legacy business.
What are contingent value rights (CVRs)?, page 5
4.We note that you disclose here and elsewhere that AVROBIO stockholders of record "as
of immediately prior to the effective time" will receive one non-transferable CVR for each
outstanding share of AVROBIO common stock held by such stockholder on such
date. However, disclosure following the first bullet on page 190 states that a record date
will be agreed to by AVROBIO and Tectonic prior to the effective time, and disclosure on
page 237 states that the record date for the CVR distribution will be the "close of business
on the business day immediately prior to the day on which the effective time
occurs." Please revise throughout to reconcile your disclosures and clarify the record date
for the issuance of CVRs to AVROBIO stockholders.
Will the common stock of the combined company trade on an exchange?, page 7
5.You disclose that AVROBIO intends to file an initial listing application for the combined
company’s common stock with Nasdaq and that it is expected that such common stock
will trade on the exchange. We also note Section 6.10 of the Merger Agreement provides
that the approval of the listing of the additional shares of AVROBIO's common stock on
Nasdaq shall have been conditionally approved prior to the Effective Time.
•Please revise the Letter to Stockholders, Q&A, and elsewhere throughout as
appropriate to clarify that the closing of the merger is conditioned upon Nasdaq’s
approval of the listing application.
•Disclose whether this condition is waivable and if so, by which party or parties.
•Indicate whether or not Nasdaq’s determination will be known at the time that
stockholders are asked to vote to approve the merger.
•Please also include a cross-reference to risk factor disclosure stating that the potential
reverse stock split may not result in an increase in the combined company’s stock
price necessary to satisfy Nasdaq’s initial or continued listing requirements for the
combined company.
What are the material U.S. federal income tax consequences of the merger to U.S. Holders of
Tectonic common stock?, page 11

 FirstName LastNameErik Ostrowski
 Comapany NameAVROBIO, Inc.
 March 12, 2024 Page 3
 FirstName LastNameErik Ostrowski
AVROBIO, Inc.
March 12, 2024
Page 3
6.We note your representation here and beginning on page 219 that the parties “intend” the
merger to qualify as a reorganization within the meaning of Section 368(a) of the U.S.
Internal Revenue Code of 1986, as amended (the “Code”). Please revise your disclosure
here and throughout, including the sections addressing the tax consequences of the
CVRs, to provide counsel’s firm opinion for each material tax consequence, including
whether the merger will qualify as a reorganization, or to explain why such opinion cannot
be given. If the opinion is subject to uncertainty, please: (1) provide an opinion that
reflects the degree of uncertainty (e.g., “should” or “more likely than not”) and explains
the facts or circumstances giving rise to the uncertainty; and (2) provide disclosure of the
possible alternative tax consequences including risk factor and/or other appropriate
disclosure setting forth the risks of uncertain tax treatment to investors. Also, please file
the tax opinion as an exhibit to the registration statement. Please refer to Item 601(b)(8) of
Regulation S-K and Section III.A. of Staff Legal Bulletin 19, Legality and Tax Opinions
in Registered Offerings.
Prospectus Summary
The Companies
AVROBIO, page 13
7.With reference to your disclosure on pages 13 and 17, please revise the Summary and the
Q&A to highlight, if true, that if the merger is completed, the combined company will
focus on developing Tectonic's product candidates, and it is anticipated that the combined
company will not continue to develop AVROBIO's legacy product candidates. Also,
revise the Q&A on page 5 to provide context for the discussion of the CVRs.
Tectonic, page 14
8.Please revise the Summary and Tectonic's Business section to provide context and balance
to the discussion of Tectonic's proprietary technology platform, GEODe. To the extent
you highlight the capabilities of the platform and Tectonic's belief that it can "overcome
the existing challenges of GPCR-targeted drug discovery" when engineering product
candidates, please also explain that Tectonic has limited experience in
therapeutic discovery and development and that the platform may never result in the
regulatory approval of a product candidate.
Interests of AVROBIO's Directors and Executive Officers in the Merger, page 20
9.Here and in the parallel sections of the registration statement regarding the interests of
Tectonic's directors and executive officers in the merger, please revise to quantify the
value of the interests of such parties. For example only, please disclose on an aggregate
basis:
•the value of options to purchase AVROBIO common stock that will be subject to
accelerated vesting, and the value of RSUs that will be subject to accelerated vesting
and settlement into shares of AVROBIO common stock, including any necessary

 FirstName LastNameErik Ostrowski
 Comapany NameAVROBIO, Inc.
 March 12, 2024 Page 4
 FirstName LastNameErik Ostrowski
AVROBIO, Inc.
March 12, 2024
Page 4
assumptions; and
•the amount of additional cash payments or "golden parachute" compensation to be
received in connection with the merger due to change in control agreements,
employment contract terminations, consulting fees, etc.
10.Here and elsewhere as appropriate, please revise to explain whether any material
payments to AVROBIO's executives, such as "golden parachute" compensation that is
based on or otherwise relates to the merger, will be excluded from the calculation of "net
cash" at the determination time, and if so, disclose the types and aggregate amounts of
such payments and explain the impact to other AVROBIO stockholders. In this regard, we
note your disclosure regarding the calculation of AVROBIO's net cash beginning on page
216 and your disclosures throughout that under certain circumstances the ownership
percentages in the combined company may be adjusted up or down depending on the
amount of AVROBIO’s net cash as of closing.
Risk Factors
Risks Related to the Proposed Reverse Stock Split, page 38
11.We note your disclosure that the principal purpose of the reverse stock split is to increase
AVROBIO's common stock price so that the combined company is able to meet initial
Nasdaq listing requirements and the shares of AVROBIO common stock being issued in
the merger will be approved for listing. In your risk factors and elsewhere as appropriate:
•Please disclose the minimum size of the reverse split that will be necessary for listing.
•Please indicate the criteria, if any, for the ratio to be used for the reverse stock split.
For example, indicate whether you intend to use the minimum ratio or a larger ratio
in an attempt for a higher price per share subsequent to the reverse stock split.
•Explain the effects on the proposed transaction and/or the combined company of a
failure to comply with the initial listing requirements of Nasdaq. If the Nasdaq listing
approval of the combined company is a condition that can be waived, please include a
discussion of the potential consequences to investors, including the ability of
investors to buy and sell shares of common stock, if the Nasdaq does not approve the
listing application of the combined company, but the election is made to waive the
closing condition and proceed with the merger.
•You state on page 39 that there can be no assurance that the stock price of the
combined company will meet the listing requirements for any meaningful period of
time. Please enhance your disclosure to explain the effects on the combined company
and its shareholders of a failure to comply with the continued listing requirements of
Nasdaq, including the potential delisting of its common stock and its impact.  Please
similarly revise your summary risk factor on page 30 to explain the effect on
combined company if the reverse stock split does not increase the combined
company’s stock price over both the short- or long-term so as to qualify for Nasdaq
listing.
Risk Factors

 FirstName LastNameErik Ostrowski
 Comapany NameAVROBIO, Inc.
 March 12, 2024 Page 5
 FirstName LastNameErik Ostrowski
AVROBIO, Inc.
March 12, 2024
Page 5
Risks Related to AVROBIO, page 43
12.You state in the risk factor on page 89 that: "In particular, AVROBIO had in-
licensed certain intellectual property rights and know-how from the University Health
Network (“UHN”) (relevant to AVR-RD-01 and AVROBIO’s Fabry program, which
AVROBIO deprioritized in January 2022) and affiliates of Lund University (relevant
to AVR-RD-02 and AVROBIO’s Gaucher type 1 and type 3 programs), which license
agreement was terminated as of January 4, 2024." Please revise herein as applicable to
more clearly disclose, if true, that the termination of the license agreement was only with
UHN, as we note the development of AVROBIO's Gaucher disease program with Lund
University appears to remain in effect, as indicated on page 321 and elsewhere.
AVROBIO's HSC lentiviral-based gene therapy product candidates are based on a novel
technology..., page 53
13.Please revise to remove or revise conclusory statements regarding AVROBIO product
candidates' performance. In this regard, we note your reference to "favorable preliminary
results observed to date."
Risks Related to Tectonic, page 102
14.In the risk factor on page 105, you disclose that Tectonic concluded that its recurring
losses from operations and need for additional financing to fund future operations raise
substantial doubt about its ability to continue as a going concern in its financial statements
for the year ended December 31, 2022 and the nine months ended September 30, 2023 and
that "Similarly, Tectonic’s independent registered public accounting firm included an
explanatory paragraph in its report on Tectonic’s financial statements for the year ended
December 31, 2022 and the nine months ended September 30, 2023 with respect to this
uncertainty." Please revise this sentence to remove the implication that a report was issued
by Tectonic's auditor for the nine months ended September 30, 2023.
The bylaws of the combined company will provide that..., page 160
15.Consistent with your risk factor disclosure on page 101, please revise to state that there is
uncertainty as to whether a court would enforce the Federal Forum provision in the
combined company's bylaws. In this regard, we note that Section 22 of the Securities Act
creates concurrent jurisdiction for federal and state courts over all suits brought to enforce
any duty or liability created by the Securities Act or the rules and regulations thereunder.
The Merger
Background of the Merger, page 171
16.You disclose that at the July 6, 2023 meeting, the AVROBIO Board and management
identified certain reverse merger candidate criteria ("Critera"), and that such Critera
"continued to be discussed, expanded and/or refined at subsequent meetings of the Board

 FirstName LastNameErik Ostrowski
 Comapany NameAVROBIO, Inc.
 March 12, 2024 Page 6
 FirstName LastNameErik Ostrowski
AVROBIO, Inc.
March 12, 2024
Page 6
and Transaction Committee."  Please revise your background disclosure to explain how
and why the Criteria evolved subsequent to the July 6, 2023 meeting, and identify who
proposed any expansion, refinement or revision of the Criteria and any material resulting
discussion in this regard.
17.With respect to the various starting pools of potential reverse merger transaction
candidates:
•Please revise page 174 to explain how advisor TD Cowen identified and selected the
initial 85 companies to which it began distributing process letters on July 18, 2023,
including with respect to the Criteria identified by the AVROBIO Board and
management at the July 6, 2023 meeting.
•Revise page 179 to explain how AVROBIO management and its advisors selected the
companies with which to engage or re-engage following the termination of
discussions with Party O, including with respect to the discussions of initial
impressions of quality and actionability across the Critera at the October 23, 2023
meeting.
18.Please revise page 178 to explain Party O's relative strengths in relation to the Criteria that
led the Transaction Committe to determine to proceed to a term sheet with Party O.
19.Please revise the November 10, 2023 and November 17, 2023 entries on pages 180
and 181, respectively, to:
•Summarize the Transaction Committee's discussions of their impressions of the
quality and actionability of Tectonic and Party R across the Criteria as reverse merger
counterparties.
•Additionally, please revise pages 180-182 to describe the "uncertainties" and
"continued" concerns about Party R’s ability to meet one or more of the Criteria as
compared to Tectonic that were discussed at various meetings.
•Further with respect to the November 17, 2023 entry, explain why the Transaction
Committee determined to continue to evaluate and negotiate terms with Company R
in light of the Committee's decision the same day to decline to advance other
companies' proposals to the term sheet phase due to weaknesses with respect to at
least one of the Criteria.
20.Please revise to explain the interactions between the representatives and advisors of
AVROBIO and Party R from and after the

CORRESP
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CORRESP

 AVROBIO, Inc.

One Kendall Square

Building 300, Suite 201

Cambridge, MA 02139

 January 10, 2020

 Via EDGAR Transmission

 United States
Securities and Exchange Commission

 Division of Corporation Finance

100 F Street, N.E.

 Washington, D.C. 20549

Re:
 AVROBIO, Inc.

Registration Statement on Form S-3 filed December 20, 2019 (File
No. 333-235641)

 Ladies and Gentlemen:

Pursuant to Rule 461 under the Securities Act of 1933, as amended (the “Act”), AVROBIO, Inc. (the “Company”) hereby requests
that the effective date of the above-referenced registration statement (the “Registration Statement”) be accelerated to January 14, 2020, at 4:01 pm Eastern Time, or as soon thereafter as practicable, unless we or our outside
counsel, Goodwin Procter LLP, request by telephone that such Registration Statement be declared effective at some other time. In making this acceleration request, the Company acknowledges that it is aware of its responsibilities under the Act.

If you have any questions regarding this request, please contact James Xu of Goodwin Procter LLP at (617) 570-1483.

 [Remainder of page intentionally blank]

 Sincerely,

 AVROBIO, INC.

 /s/ Geoff MacKay

 Geoff MacKay

 President and Chief Executive Officer

 cc:    Erik Ostrowski, AVROBIO, Inc.

Arthur R. McGivern, Esq., Goodwin Procter LLP

 James Xu,
Esq., Goodwin Procter LLP

CORRESP
1
filename1.htm

CORRESP

 Goodwin Procter LLP

 100 Northern Avenue

Boston, MA 02210

 goodwinlaw.com

+1 617 570 1000

 January 2, 2020

 VIA
FEDERAL EXPRESS AND EDGAR

 United States Securities and Exchange Commission

Division of Corporation Finance

 100 F Street, N.E.

Washington, D.C. 20549

 Attention:

Irene Paik

 Mary Beth Breslin

Re:
 AVROBIO, Inc.

Registration Statement on Form S-3

Filed December 20, 2019

File No. 333-235641

Ladies and Gentlemen:

 This letter is being submitted on behalf
of AVROBIO, Inc. (the “Company”) in response to the comment from the Staff (the “Staff”) of the U.S. Securities and Exchange Commission (the “Commission”) with respect to the above-referenced
Registration Statement on Form S-3 (the “Registration Statement”) that was filed with the Commission on December 20, 2019, as set forth in the Staff’s letter to the Company dated
December 27, 2019 (the “Comment Letter”).

 For reference purposes, the text of the Staff’s numbered comment set forth in the
Comment Letter has been reproduced in italics herein with our response immediately following the comment. Unless otherwise indicated, page references in the description of the Staff’s comment and in the response refer to the Registration
Statement. All capitalized terms used and not otherwise defined herein shall have the meanings set forth in the Registration Statement.

 The responses
provided herein are based upon information provided to Goodwin Procter LLP by the Company. In addition to submitting this letter via EDGAR, we are sending via Federal Express four (4) copies of this letter.

Registration Statement on Form S-3 filed December 20, 2019

Description of Capital Stock

 Choice of Forum, page 13

1.
 We note your disclosure on page 13 that your forum selection provision in your amended and restated bylaws
identifies the Court of Chancery of the State of Delaware as the exclusive forum “for any state law claim” for certain litigation, including any “derivative action.” However, we note that your forum selection bylaw does not
include a state law claim limitation. Please advise, or expand your disclosure to, if true, explicitly state that this provision does not apply to actions arising under the Exchange Act.

 Securities and Exchange Commission

January 2, 2020

 Page 2

 RESPONSE: The Company acknowledges the Staff’s comment. The Company respectfully
advises the Staff that while the Company’s amended and restated bylaws do not explicitly address actions arising under the Exchange Act, the Company acknowledges that there is exclusive federal jurisdiction for actions arising under the
Exchange Act. Accordingly, the Company has disclosed in its prior filings with the Commission its view that the Company’s forum selection provision, as it relates to the Delaware Chancery Court, does not apply to actions arising under the
Exchange Act. Specifically, the Company directs the Staff to its most recent Quarterly Report on Form 10-Q for the period ended September 30, 2019, which is incorporated by reference into the Registration
Statement. In that quarterly report, the Company discloses that (emphasis added):

 “Our amended and restated bylaws provide that,
unless we consent in writing to an alternative forum, the Court of Chancery of the State of Delaware will be the sole and exclusive forum for any state law claim for (1) any derivative action or proceeding brought on our behalf; (2) any
action asserting a claim of breach of or based on a fiduciary duty owed by any of our current or former directors, officers or other employees to us or our stockholders; (3) any action asserting a claim against us or any of our current or
former directors, officers, employees or stockholders arising pursuant to any provision of the Delaware General Corporation Law, our amended and restated certificate of incorporation or our amended and restated bylaws; or (4) any action
asserting a claim governed by the internal affairs doctrine (the “Delaware Forum Provision”). The Delaware Forum Provision will not apply to any causes of action arising under the Securities Act of 1933 or the Securities Exchange Act
of 1934. Our amended and restated bylaws further provide that, unless we consent in writing to an alternative forum, the United States District Court for the District of Massachusetts will be the exclusive forum for resolving any complaint
asserting a cause of action arising under the Securities Act (the “Federal Forum Provision”). We have chosen the United States District Court for the District of Massachusetts as the sole and exclusive forum for such Securities Act causes
of action because our principal executive offices are located in Cambridge, Massachusetts. In addition, our amended and restated bylaws provide that any person or entity purchasing or otherwise acquiring any interest in shares of our capital stock
is deemed to have notice of and consented to the foregoing Delaware Forum Provision and the Federal Forum Provision.”

 The Registration Statement
expressly incorporates by reference the Company’s Quarterly Report on Form 10-Q for the period ended September 30, 2019 and the disclosure contained therein. While the current disclosure in the
Registration Statement does not expressly repeat the disclosure from the quarterly report, it does not conflict with or contradict the information incorporated by reference from the quarterly report. In addition, for so long as the statement remains
accurate, the Company intends to include similar disclosure for its future filings to be incorporated by reference into the Registration Statement, including prospectuses under the Registration Statement and supplements thereto. For the foregoing
reasons, the Company believes that the Registration Statement and its disclosures summarizing the terms of the Company’s amended and restated bylaws are consistent in all material respects with those bylaws, and therefore no amendment to the
Registration Statement is necessary.

 If you have any questions or comments regarding the foregoing, or if there is any additional information that we
might provide to assist the Staff’s review, please contact the undersigned at (617) 570-1483.

[Remainder of page intentionally blank]

 Securities and Exchange Commission

January 2, 2020

 Page 3

Respectfully submitted,

 /s/ James Xu

James Xu, Esq.

 GOODWIN PROCTER LLP

cc:

Geoff MacKay, AVROBIO, Inc.

Erik Ostrowski, AVROBIO, Inc.

Steven Avruch, AVROBIO, Inc.

Arthur R. McGivern, Esq., Goodwin Procter LLP

December 27, 2019
Geoff MacKay
President and Chief Executive Officer
AVROBIO, Inc.
One Kendall Square
Building 300, Suite 201
Cambridge, MA 02139
Re:AVROBIO, Inc.
Registration Statement on Form S-3
Filed December 20, 2019
File No. 333-235641
Dear Mr. MacKay:
            We have limited our review of your registration statement to those issues we have
addressed in our comment.
            Please respond to this letter by amending your registration statement and providing the
requested information.  If you do not believe our comment applies 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 this comment, we may have
additional comments.
Registration Statement on Form S-3 filed December 20, 2019
Description of Capital Stock
Choice of Forum, page 13
1.We note your disclosure on page 13 that your forum selection provision in your amended
and restated bylaws identifies the Court of Chancery of the State of Delaware as the
exclusive forum "for any state law claim" for certain litigation, including any “derivative
action.”  However, we note that your forum selection bylaw does not include a state law
claim limitation.  Please advise, or expand your disclosure to, if true, explicitly state that
this provision does not apply to actions arising under the Exchange Act.
            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.

 FirstName LastNameGeoff MacKay
 Comapany NameAVROBIO, Inc.
 December 27, 2019 Page 2
 FirstName LastName
Geoff MacKay
AVROBIO, Inc.
December 27, 2019
Page 2
            Refer to Rules 460 and 461 regarding requests for acceleration.  Please allow adequate
time for us to review any amendment prior to the requested effective date of the registration
statement.
            Please contact Irene Paik at 202-551-6553 or Mary Beth Breslin at 202-551-3625 with
any questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       James H. Xu - Goodwin Procter LLP

CORRESP
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CORRESP

 AVROBIO, Inc.

One Kendall Square

Building 300, Suite 201

Cambridge, MA 02139

 July 8, 2019

 Via EDGAR Transmission

 United States
Securities and Exchange Commission

 Division of Corporation Finance

100 F Street, N.E.

 Washington, D.C. 20549

Re:
 AVROBIO, Inc.

Registration Statement on Form S-3 filed July 1, 2019 (File
No. 333-232489)

 Ladies and Gentlemen:

Pursuant to Rule 461 under the Securities Act of 1933, as amended (the “Act”), AVROBIO, Inc. (the “Company”) hereby requests
that the effective date of the above-referenced registration statement (the “Registration Statement”) be accelerated to July 10, 2019, at 4:01 pm Eastern Time, or as soon thereafter as practicable, unless we or our outside
counsel, Goodwin Procter LLP, request by telephone that such Registration Statement be declared effective at some other time. In making this acceleration request, the Company acknowledges that it is aware of its responsibilities under the Act.

If you have any questions regarding this request, please contact James Xu of Goodwin Procter LLP at (617) 570-1483.

 Sincerely,

 AVROBIO, INC.

/s/ Geoff MacKay

 Geoff MacKay

 President and Chief Executive
Officer

cc:
 Erik Ostrowski, AVROBIO, Inc.

Arthur R. McGivern, Esq., Goodwin Procter LLP

James Xu, Esq., Goodwin Procter LLP

July 3, 2019
Geoff MacKay
President and Chief Executive Officer
AVROBIO, Inc.
One Kendall Square
Building 300, Suite 201
Cambridge, MA 02139
Re:AVROBIO, Inc.
Registration Statement on Form S-3
Filed July 1, 2019
File No. 333-232489
Dear Mr. MacKay:
            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 Irene Paik at 202-551-6553 with any questions.
Sincerely,
Division of Corporation Finance
Office of Healthcare & Insurance
cc:       James Xu - Goodwin Procter LLP

CORRESP
1
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CORRESP

 June 18, 2018

VIA EDGAR

 U.S. Securities and Exchange Commission

 Division of Corporation Finance

 100 F Street, N.E.

Washington, D.C. 20549

Re:
AVROBIO, Inc.

 Registration Statement on Form
S-1 (File No. 333-225213) (the “Registration Statement”)

Ladies and Gentleman:

 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 AVROBIO, Inc. that the effective date of the Registration Statement be accelerated so that it will
be declared effective at 4:00 p.m. Eastern Time on June 20, 2018, or as soon thereafter as practicable.

 Pursuant to Rule 460 under the Act, please
be advised that we and the other prospective underwriters have distributed approximately 2,911 copies of the preliminary prospectus dated June 11, 2018 (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, we hereby confirm that we are, and
the other prospective underwriters have confirmed that they are, complying with the 48-hour requirement as promulgated by Rule 15c2-8 under the Securities Exchange Act
of 1934, as amended.

 [Remainder of page intentionally left blank]

 Very truly yours,

MORGAN STANLEY & CO. LLC

COWEN AND COMPANY, LLC

WELLS FARGO SECURITIES, LLC

As Representatives of the several Underwriters

MORGAN STANLEY & CO. LLC.

By:

 /s/ Albert Hwang

Name:

Albert Hwang

Title:

Managing Director

COWEN AND COMPANY LLC

By:

 /s/ Jason Fenton

Name:

Jason Fenton

Title:

Managing Director

WELLS FARGO SECURITIES, LLC

By:

 /s/ David Herman

Name:

David Herman

Title:

Director

 [Signature Page to Request for Acceleration of Effectiveness]

CORRESP
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CORRESP

 VIA EDGAR

June 18, 2018

 United States Securities and Exchange
Commission

 Division of Corporation Finance

 Mail Stop 4561

 100 F Street, N.E.

 Washington, D.C. 20549

Attention: Dorrie Yale

Re:
AVROBIO, Inc.

 Acceleration Request for Registration Statement on Form S-1

 File No. 333-225213

Dear Ms. Yale:

 Pursuant to Rule 461 under
the Securities Act of 1933, as amended (the “Act”), AVROBIO, Inc. (the “Company”) hereby requests that the effective date of the above-referenced registration statement (the “Registration
Statement”) be accelerated to June 20, 2018, at 4:00 p.m., Eastern Time, or as soon thereafter as practicable, unless we or our outside counsel, Goodwin Procter LLP, request by telephone that such Registration Statement be declared
effective at some other time. In making this acceleration request, the Company acknowledges that it is aware of its responsibilities under the Act.

Once the Registration Statement is effective, please orally confirm the event with our counsel, Goodwin Procter LLP by calling James Xu at
(617) 570-1483. We also respectfully request that a copy of the written order from the Securities and Exchange Commission (the “Commission”) verifying the effective time and date of the
Registration Statement be sent to our counsel, Goodwin Procter LLP, Attention: James Xu, by facsimile to (617) 523-1231.

 If you have any questions regarding this request, please contact James Xu of Goodwin Procter LLP
at (617) 570-1483.

 Sincerely,

 AVROBIO, INC.

 /s/ Geoff MacKay

Geoff MacKay

President and Chief Executive Officer

cc:
Katina Dorton, Chief Financial Officer, AVROBIO, Inc.

 Arthur McGivern, Esq., Goodwin
Procter LLP

 James Xu, Esq., Goodwin Procter LLP

CORRESP
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filename1.htm

CORRESP

 Goodwin Procter LLP

 100 Northern Avenue
Boston, MA 02210

 goodwinlaw.com

 +1 617 570 1000

 June 15, 2018

 VIA
FEDERAL EXPRESS AND EDGAR

 United States Securities and Exchange Commission

Division of Corporation Finance

 100 F Street, N.E.

Washington, D.C. 20549

 Attention:

Rolf Sundwall

 Jim Rosenberg

Dorrie Yale

 Suzanne Hayes

Re:    AVROBIO, Inc.

 Amendment
No. 2 to Registration Statement on Form S-1

 File No.
333-225213

 CIK No. 0001681087

Ladies and Gentlemen:

 This letter is being submitted on behalf
of AVROBIO, Inc. (the “Company”) in response to comments of the Staff (the “Staff”) of the U.S. Securities and Exchange Commission (the “Commission”) with respect to the above-referenced Amendment
No. 2 to Registration Statement (the “Registration Statement”) that was filed with the Commission on June 11, 2018, as set forth in the Staff’s letter to the Company dated June 13, 2018 (the “Comment
Letter”).

 For reference purposes, the text of the Comment Letter has been reproduced herein with responses below each numbered comment. For your
convenience, we have italicized the reproduced Staff comments from the Comment Letter. Unless otherwise indicated, page references in the descriptions of the Staff’s comments and in the responses refer to the Registration Statement. All
capitalized terms used and not otherwise defined herein shall have the meanings set forth in the Registration Statement.

 For the Staff’s convenience
and to facilitate the Staff’s analysis of the Comment Letter, the Company’s responses below do not give the effect to the 1-for-4.132 reverse stock split that
was completed on June 7, 2018, as described in the Registration Statement.

 The responses provided herein are based upon information provided to
Goodwin Procter LLP by the Company. In addition to submitting this letter via EDGAR, we are sending via Federal Express four (4) copies of this letter.

 Securities and Exchange Commission

June 15, 2018

  Page
 2

 Amendment No. 2 to Registration Statement on Form
S-1 Submitted on June 11, 2018

 Prospectus Summary, page 1

1.
We note your revised disclosure that you have initiated a Phase 2 trial for AVR-RD-01, and that the “Expected Next Milestone”
column in your revised pipeline table now states that the next step for this product candidate is to receive the first phase 2 patient data. We also note your disclosure on pages 16-17 that both the Phase 1
and Phase 2 trials for AVR-RD- 01 are ongoing and need to be completed. Please revise your pipeline table here and in the Business section to clarify that the Phase 1
trial has not been completed and that the expected next milestone includes receiving patient data from both the Phase 1 and Phase 2 trials.

RESPONSE: The Company respectfully advises the Staff that it will revise its disclosures on pages 2, 89 and 95 in a future amendment to the Registration
Statement in response to the Staff’s comment to include a pipelines table substantially in the form of the below graphic.

 Use of Proceeds, page 59

2.
We note your disclosure that you estimate that you will use the proceeds from the offering, together with your existing cash, to advance
AVR-RD-01 into Phase 2 clinical trials and to support the phase 1 clinical trial; to advance
AVR-RD-02 into Phase 1/2 clinical trials; AVR-RD-03 into preclinical development; etc.
Please revise your disclosure to clarify whether you expect to complete any of these trials with the proceeds from the offering and existing cash. If not, please clarify that you do not expect the proceeds to be sufficient to complete any of these
phases.

 RESPONSE: The Company respectfully advises the Staff that it will revise its disclosures on page 59 in a future amendment to
the Registration Statement in response to the Staff’s comment to clarify that, based on the Company’s current plans, the Company believes that the amounts allocated as described on page 59 under Use of Proceeds are sufficient for the
completion of the ongoing Phase 1 and Phase 2 clinical trials for AVR-RD-01, but are insufficient to complete the studies and trials for
AVR-RD-02, AVR-RD-03 and
AVR-RD-04 or subsequent clinical trials of AVR-RD-01. The Company supplementally advises the Staff that it expects that such
disclosure to be in substantially the form set forth below.

 We currently estimate that we will use the net proceeds from this offering,
together with our existing cash and cash equivalents of $57.9 million as of March 31,2018, as follows:

•

approximately $13.4 million to fund expenses for our lead product candidate, AVR-RD-01, for the treatment of Fabry disease in our ongoing Phase 2 clinical trial and to support the ongoing investigator-sponsored Phase I
clinical trial;

•

approximately $12.9 million to fund expenses to advance AVR-RD-02 for the treatment of Gaucher disease into Phase 1/2 clinical trials;

•

approximately $3.2 million to fund expenses to advance AVR-RD-03 for Pompe disease further into preclinical development;

•

approximately $5.4 million to fund expenses to advance AVR-RD-04 for the treatment of cystinosis, including to support the planned initial investigator-sponsored Phase 1/2 clinical trial;

•

approximately $28.0 million to fund expenses for our external and internal manufacturing and process development activities related to the advancement of our product candidates;

•

approximately $32.6 million to fund research and development activities that relate to all of our clinical and preclinical activities, including the cost of research and development personnel; and

•

the remainder for planned general and administrative expenses, the costs of operating as a public company, working capital and other general corporate purposes.

Based on our current plans, we expect that the proceeds allocated as described above will be sufficient to complete the ongoing Phase 1 and
Phase 2 clinical trials for AVR-RD-01, but will be insufficient to complete the above referenced trials and studies for AVR-RD-02, AVR-RD-03 and AVR-RD-04 or subsequent clinical trials of AVR-RD-01. Based on our current plans, we believe our
existing cash and cash equivalents, together with the net proceeds from this offering, will be sufficient to fund our operations into 2020.

 The Company
supplementally advises the Staff that, as disclosed in the Use of Proceeds section of the Registration Statement, the amounts and timing of its expenditures may vary significantly due to inherent uncertainty of clinical development and the numerous
factors discussed in the Risk Factors section of the Registration Statement. For the foregoing reasons, the Company respectfully advises the Staff that it believes specifically quantifying at this time the funds needed to complete studies or trials
for AVR-RD-02, AVR-RD-03 and AVR-RD-04 would be premature and speculative.

 Business

Phase 2 Multinational Clinical Trial, page 99

3.
Please explain to us your revised disclosure, which indicates that you commenced your Phase 2 trial in Australia, but that you received regulatory approval to proceed from Canada.

 2

 Securities and Exchange Commission

June 15, 2018

  Page
 3

 RESPONSE: The Company respectfully advises the Staff that it will revise its disclosures on page 99 in a
future amendment to the Registration Statement in response to the Staff’s comment. The Company supplementally advises the Staff that it expects that such disclosure to be in substantially the form set forth below.

Phase 2 Multinational Clinical Trial

On June 7, 2018, we dosed the first patient in our open label, multinational Phase 2 clinical trial of AVR-RD-01 in 2018. Enrollment in
our Phase 2 clinical trial is ongoing, and we expect to enroll eight to 12 treatment-naïve males, 16 years and older, with classic Fabry disease. Our objectives for this trial are to assess safety and efficacy as measured by
multiple indicators, such as Gb3 levels in various tissues, kidney and cardiac function, gastrointestinal symptoms, and pain and quality of life scores. All enrolled patients will receive a single treatment with AVR-RD-01 and will be followed
for 48 weeks to measure safety and efficacy. We received approval from both the Australian and Canadian regulatory authorities to initiate our Phase 2 clinical trial for AVR-RD-01, and, on June 7, 2018, the first patient in this
clinical trial was dosed at an Australian site. We also plan to submit applications to allow commencement of clinical trials in the United States to the FDA and in Japan to the Pharmaceuticals and Medical Devices Agency, or PMDA, following meetings
with each of these respective regulatory authorities.

 Letter dated June 1, 2018 regarding determination of fair value of the Company’s
common stock Valuations, page 3

4.
Refer to your response to Comment 2 from our June 8, 2018 letter. Please reconcile for us the significant increase in the IPO scenario price per share as of March 31, 2018 as per
your June 11, 2018 response to the estimated IPO mid-point price before effecting the reverse stock split.

RESPONSE: The Company advises the Staff that, as disclosed in the Registration Statement, the fair value of the Company’s common stock as
of the March 16, 2018 option grants was retrospectively adjusted as a result of a contemporaneous valuation performed as of March 31, 2018. The fair value of the common stock as of March 31, 2018 was determined utilizing a probability
weighted expected return method that utilized two scenarios, an initial public offering (IPO) scenario and a remain private scenario, which resulted in a total fair value per share of $1.46. The fair value in the IPO scenario was determined to be
$1.93, which was based on a future projected IPO price per share of $2.45, which was adjusted for a discount for lack of marketability and to record the amount at present value. The mid-point of the range for
the IPO was estimated to be $4.11 per share as of June 11, 2018. The difference between the future projected IPO price per share of $2.45 and the mid-point of the estimate range of $4.11 of $1.66 per
share, or 68%, was primarily due to changes in the market between March 31, 2018 and June 11, 2018, evidence of greater acceptance of offerings by biotechnology companies focused on gene therapy, and advancements in the Company’s
clinical development. Specifically, in addition to the factors set forth in the Company’s letter to the Staff dated June 1, 2018, the Company notes the following factors that contributed to the overall increase in value between March 31,
2018 and June 11, 2018:

•

As noted above, the March 31, 2018 valuation was adjusted for a discount for lack of marketability and to record the amount at present value. This contributed to approximately 27% of the increase ($1.93 per share
compared to $2.45 per share).

•

From April 2, 2018 to June 11, 2018, the stock price for the guideline companies increased by a median percentage of 14% and an average of 24% Certain guideline companies significantly exceeded the 68%
increase from the projected IPO price as of March 31, 2018 to the mid-point of the estimated range, including Solid Biosciences which increased by 111.1% and Sangamo Therapeutics which increased by 72.2%.
As a result, the increase was within the range determined through review of the guideline companies.

•

On April 9, 2018, the stock price for AveXis, Inc., a gene-therapy company, increased by 78% after an acquisition was announced by Novartis for $8.7 billion, representing an 88% premium to the market
capitalization of AveXis on the date the acquisition was announced.

•

 Evidence of significant demand for biotechnology IPOs with eleven IPOs completed since March 31, 2018. These
IPOs include MorphoSys AG (4/19/18), Surface Oncology (4/19/18), Inspire Medical Systems (5/3/18), Unity Biotechnology (5/3/18), ASLAN Pharmaceuticals (5/4/18), Evelo Biosciences (5/9/18), Kiniksa

 3

 Securities and Exchange Commission

June 15, 2018

  Page
 4

Pharmaceuticals (5/24/18), Scholar Rock Holdings (5/24/18), Iterum Therapeutics (5/25/18), Hancock Jaffe Laboratories (5/31/18), and MeiraGTx Holdings (6/8/18).

•

Recent IPO on June 8, 2018 of MeiraGTx Holdings, a gene therapy company, which completed an IPO that indicated an enterprise value of $313.2 million, which approximates the enterprise value implied by the mid-point of the estimated range used by the Company.

•

Strong aftermarket performance of 2018 recent gene therapy IPOs of Homology Medicines, Inc. and Solid Biosciences, which were up 27% and 53% respectively since their effective IPO price to June 11, 2018.

•

The Company dosed the first patient in its Phase 2 clinical trial for Fabry disease on June 7, 2018 and therefore entered into late stage clinical development. This patient is only the third patient dosed in
clinical trials for AVR-RD-01, and this Phase 2 trial is the first Company-sponsored clinical trial for any of the Company’s pipeline products. In connection with
entering into Phase 2 development, the Company achieved significant operational milestones, including building international infrastructure, obtaining site approvals and regulatory clearances to initiate its Phase 2 clinical trial, which were
capabilities that the Company previously utilized its academic partner, University Health Network, to achieve.

 Based on the factors noted
above, including increases in the market from March 31, 2018 to June 11, 2018 for the guideline companies, recent evidence of market acceptance for offerings related to entities focused on gene therapy, and advancements in the Company’s
clinical development, the Company believes the difference in value reflected between the estimated price range and the determination of the fair value of its common stock as of March 31, 2018 was appropriate. However, in response to the Staffs
comment, the Company performed a sensitivity analysis to determine whether there would be a material change to the March 31, 2018 valuation based on hindsight assuming the Company knew the estimated IPO price of $4.11 per share at the time the March
31 2018 valuation was completed. Specifically, if the mid-point of the range was utilized as the estimated future IPO price per share, after applying the discount for lack of marketability, adjusting for
present value, and applying the weighted-average derived value with the remain private scenario, the fair value of the common stock would be $2.12 per share. The difference in this amount compared to the previously determined fair value of $1.46 per
share of $0.66 per share, or 45%, would result in a difference in the stock-based compensation expense recorded in the three month period ended March 31, 2018 of $17.7 thousand, if this value was applied to the March 16, 2018 option
grants. This amount is considered to not be material to the interim financial statements or to the other information included in the Registration Statement.

If you have any questions or comments regarding the foregoing, or if there is any additional information that we might provide to assist the Staff’s
review, please contact the undersigned at (617) 570-1483.

Respectfully submitted,

/s/ James Xu

James Xu, Esq.

 GOODWIN PROCTER LLP

cc:
Geoff MacKay, AVROBIO, Inc.

Katina Dorton, AVROBIO, Inc.

Arthur R. McGivern, Esq., Goodwin Procter LLP

 4

June 13, 2018
Geoff MacKay
President and Chief Executive Officer
AVROBIO, Inc.
One Kendall Square
Building 300, Suite 201
Cambridge, MA 02139
Re:AVROBIO, Inc.
Amendment No. 2 to Registration Statement on Form S-1
Filed June 11, 2018
Response dated June 1, 2018
File No. 333-225213
Dear Mr. MacKay:
            We have reviewed your amended 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 amending your registration statement and providing the
requested information.  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 any amendment to your registration statement and the information you
provide in response to these comments, we may have additional comments.
Registration Statement on Form S-1
Prospectus Summary, page 1
1.We note your revised disclosure that you have initiated a Phase 2 trial for AVR-RD-01,
and that the "Expected Next Milestone" column in your revised pipeline table now states
that the next step for this product candidate is to receive the first phase 2 patient data.  We
also note your disclosure on pages 16-17 that both the Phase 1 and Phase 2 trials for AVR-
RD-01 are ongoing and need to be completed.  Please revise your pipeline table here and
in the Business section to clarify that the Phase 1 trial has not been completed and that the

 FirstName LastNameGeoff MacKay
 Comapany NameAVROBIO, Inc.
 June 13, 2018 Page 2
 FirstName LastName
Geoff MacKay
AVROBIO, Inc.
June 13, 2018
Page 2
expected next milestone includes receiving patient data from both the Phase 1 and Phase 2
trials.
Use of Proceeds, page 59
2.We note your disclosure that you estimate that you will use the proceeds from the
offering, together with your existing cash, to advance AVR-RD-01 into Phase 2 clinical
trials and to support the phase 1 clinical trial; to advance AVR-RD-02 into Phase 1/2
clinical trials; AVR-RD-03 into preclinical development; etc.  Please revise your
disclosure to clarify whether you expect to complete any of these trials with the proceeds
from the offering and existing cash.  If not, please clarify that you do not expect the
proceeds to be sufficient to complete any of these phases.
Business
Phase 2 Multinational Clinical Trial, page 99
3.Please explain to us your revised disclosure, which indicates that you commenced your
Phase 2 trial in Australia, but that you received regulatory approval to proceed from
Canada.
Letter dated June 1, 2018 regarding determination of fair value of the Company’s common stock
Valuations, page 3
4.Refer to your response to Comment 2 from our June 8, 2018 letter.  Please reconcile for us
the significant increase in the IPO scenario price per share as of March 31, 2018 as per
your June 11, 2018 response to the estimated IPO mid-point price before effecting the
reverse stock split.
            You may contact Rolf Sundwall at 202-551-3105 or Jim Rosenberg at 202-551-3679 if
you have questions regarding comments on the financial statements and related matters.  Please
contact Dorrie Yale at 202-551-8776 or Suzanne Hayes at 202-551-3675 with any other
questions.
Division of Corporation Finance
Office of Healthcare & Insurance
cc:       James Xu

June 8, 2018
Geoff MacKay
President and Chief Executive Officer
AVROBIO, Inc.
One Kendall Square
Building 300, Suite 201
Cambridge, MA 02139
Re:AVROBIO, Inc.
Registration Statement on Form S-1
Response Dated June 1, 2018
File No. 333-225213
Dear Mr. MacKay:
            We have reviewed your June 1, 2018 response to our comment letter dated May 4, 2018
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 amending your registration statement or providing the
requested information.  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 any amendment to your registration statement and the information you
provide in response to these comments, we may have additional comments.
Letter dated June 1, 2018 regarding determination of fair value of the Company's common stock
October 24, 2017 Valuation, page 3
1.Please tell us why there is not an amount recorded for beneficial conversion feature
related to the October 2017 series A preferred stock issuance considering your valuation
of $.99 per share for your common stock and that the preferred stock was issued at $.79
per share.

 FirstName LastNameGeoff MacKay
 Comapany NameAVROBIO, Inc.
 June 8, 2018 Page 2
 FirstName LastName
Geoff MacKay
AVROBIO, Inc.
June 8, 2018
Page 2
Valuations, page 3
2.Please refer to the discussions of the valuations at various dates on page 3 and 4 beginning
with the August 31, 2017 valuation. Provide us the IPO price per share before applying
the probability percentage and the discount for lack of marketability. Provide us a
description of the non-IPO scenario and the price per share before applying the discount
for lack of marketability.
            You may contact Rolf Sundwall at 202-551-3105 or Jim Rosenberg at 202-551-3679 if
you have questions regarding comments on the financial statements and related matters.  Please
contact Dorrie Yale at 202-551-8776 or Suzanne Hayes at 202-551-3675 with any other
questions.
Division of Corporation Finance
Office of Healthcare & Insurance
cc:       James Xu

CORRESP
1
filename1.htm

CORRESP

 Goodwin Procter LLP

100 Northern Avenue

 Boston, MA 02210

 goodwinlaw.com

+1 617 570 1000

CERTAIN PORTIONS OF THIS LETTER HAVE BEEN OMITTED FROM THE VERSION FILED VIA EDGAR. CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO
THE OMITTED PORTIONS. INFORMATION THAT WAS OMITTED IN THE EDGAR VERSION HAS BEEN HIGHLIGHTED IN THIS LETTER.

 June 1, 2018

FOIA Confidential Treatment Request

Pursuant to Rule 83 by AVROBIO, Inc.

VIA FEDERAL EXPRESS AND EDGAR

 United States
Securities and Exchange Commission

 Division of Corporation Finance

100 F Street, N.E.

 Washington, D.C. 20549

Attention: Dorrie Yale

Re:
AVROBIO, Inc.

Registration Statement on Form S-1

File No. 333-225213

CIK No. 0001681087

 Dear Ms. Yale:

This letter is being submitted on behalf of AVROBIO, Inc. (the “Company”) to supplement the Company’s prior responses to
the staff (the “Staff”) of the U.S. Securities and Exchange Commission (the “Commission”) with respect to the Company’s Registration Statement on Form S-1 filed on
May 25, 2018.

 On behalf of the Company, we are supplementally providing the following:

1.
A bona fide estimate of the range of the offering price for the shares of the Company’s common stock offered by the Registration Statement (before giving effect to a contemplated reverse stock split of the
Company’s common stock in connection with the offering), and a discussion of the factors that the Company believes led to the increase in the value of its common stock between the recent valuations of its common stock and the estimated price
range for the offering, attached hereto as Exhibit A.

 Ms. Dorrie Yale

Securities and Exchange Commission

 June 1, 2018

 Page
 2

2.
For the Staff’s convenience, a table summarizing stock options granted between June 1, 2017 and the date hereof, which table reflects the issuance of options to purchase shares of common stock granted by the
Company, and which the Company has included in the Registration Statement, attached hereto as Exhibit B.

3.
Proposed language that the Company intends to include in a subsequent amendment to the Registration Statement listing the significant factors contributing to any difference between its most recent common stock
valuations as of March 31, 2017, August 31, 2017, October 24, 2017, January 31, 2018 and March 31, 2018, and the midpoint of the estimated price range for this offering (before giving effect to a contemplated reverse stock
split of the Company’s common stock in connection with the offering). The Company expects that such disclosure would be generally consistent with the currently contemplated disclosure attached hereto as Exhibit C.

The Company advises the Staff that the general approach taken by the Company in determining the fair value of its common stock, including as
of March 31, 2017, which the Company’s board of directors considered for stock option grants on June 13, 2017, June 26, 2017, July 10, 2017 and July 17, 2017, as of August 31, 2017, which was used for the
retrospective fair value assessment of the stock option grants on August 28, 2017, as of October 24, 2017, which was used for the retrospective fair value assessment of the stock option grants on October 4, 2017, October 17, 2017
and October 24, 2017, and as of March 31, 2018, which was used for the retrospective fair value assessment of the stock option grants on March 16, 2018, are set forth beginning on page 81 of the prospectus included in the Registration
Statement.

 As described in the Registration Statement, the Company’s common stock valuation as of March 31, 2017 was prepared
using the option-pricing method (“OPM”). The OPM treats common stock and preferred stock as call options on the total equity value of a company, with exercise prices based on the value thresholds at which the allocation among the
various holders of a company’s securities changes. Under this method, the common stock has value only if the funds available for distribution to members or stockholders exceed the value of the preferred stock liquidation preference at the time
of the liquidity event, such as a strategic sale or a merger. The future value of the common stock is discounted back to the valuation date at an appropriate risk-adjusted discount rate and probability weighted to arrive at an indication of value
for the common stock. For the August 31, 2017, October 24, 2017, January 31, 2018 and March 31, 2018 valuations, the Company used a hybrid method, which is a hybrid between the OPM and the probability-weighted expected return
method (“PWERM”). The hybrid method estimates the probability-weighted value across multiple scenarios but uses the OPM to estimate the allocation of value within at least one of the scenarios. The Company made this change as
greater certainty developed regarding a possible liquidity event. The PWERM methodology relies on a forward-

 2

 Ms. Dorrie Yale

Securities and Exchange Commission

 June 1, 2018

 Page
 3

 looking analysis to predict the possible future value of a company. Under this method, discrete future
outcomes, such as an initial public offering (“IPO”), non-IPO scenarios, and a merger or sale are weighted based on the Company’s estimate of the probability of each scenario. In its
application of the hybrid method, the Company considered an IPO scenario under the PWERM framework, and a non-IPO scenario modeled using an OPM to reflect the full distribution of possible non-IPO outcomes. The hybrid method is useful when certain discrete future outcomes can be predicted, but also accounts for uncertainty regarding the timing or likelihood of specific alternative exit events.

March 31, 2017 Valuation

 The fair
value of the Company’s common stock of $0.22 per share as of March 31, 2017 was determined by the Company’s board of directors with the assistance of an independent third-party valuation firm. This valuation was used to support the
fair value of the Company’s common stock with respect to stock options granted on June 13, 2017, June 26, 2017, July 10, 2017 and July 17, 2017. This valuation utilized the market approach (recent transaction method) to
obtain the equity value of the Company. The valuation utilized the OPM to arrive at a common stock valuation before discounts. A discount for lack of marketability of 36% was then applied to the common stock value.

August 31, 2017 Valuation

 The fair
value of the Company’s common stock of $0.53 per share as of August 31, 2017 was retrospectively determined with the assistance of an independent third-party valuation firm. This valuation was used for the retrospective fair value
assessment of the stock option grants on August 28, 2017. This valuation utilized the hybrid method, which considered the value of the Company’s common stock in both IPO and non-IPO scenarios. The
present value of the Company’s common stock in an IPO scenario was calculated based on metrics observed from then-recent IPOs in the biotechnology industry. The value of the Company’s common stock in a
non-IPO scenario was calculated using the OPM. The valuation assumed a 10% probability of an IPO and a 90% probability of a non-IPO scenario. A discount for lack of
marketability of 20% and 30% was applied to the IPO and non-IPO scenarios, respectively.

 October 24, 2017
Valuation

 The fair value of the Company’s common stock of $0.99 per share as of October 24, 2017 was retrospectively
determined with the assistance of an independent third-party valuation firm. This valuation was used for the retrospective fair value assessment of the stock option grants on October 4, 2017, October 17, 2017 and October 24, 2017.
This valuation utilized the hybrid method, which considered the value of the Company’s common stock in both IPO and non-IPO scenarios. The present value of the Company’s common stock in an IPO
scenario was calculated based on metrics observed from then-recent IPOs in the biotechnology industry. The value of the Company’s common stock in a non-IPO scenario was calculated using the OPM. The

 Ms. Dorrie Yale

Securities and Exchange Commission

 June 1, 2018

 Page
 4

 valuation assumed a 15% probability of an IPO and an 85% probability of a
non-IPO scenario. A discount for lack of marketability of 17% and 25% was applied to the IPO and non-IPO scenarios, respectively.

January 31, 2018 Valuation

 The fair
value of the Company’s common stock of $1.21 per share as of January 31, 2018 was determined by the Company’s board of directors with the assistance of an independent third-party valuation firm. This valuation was used to support the
exercise prices of the Company’s common stock with respect to options granted on March 16, 2018, which grant date fair value of the common stock was retrospectively adjusted through the March 31, 2018 valuation. This valuation
utilized the hybrid method, which considered the value of the Company’s common stock in both IPO and non-IPO scenarios. The present value of the Company’s common stock in an IPO scenario was
calculated based on metrics observed from then-recent IPOs in the biotechnology industry. The value of the Company’s common stock in a non-IPO scenario was calculated using the OPM. The valuation assumed
a 25% probability of an IPO and a 75% probability of a non-IPO scenario. A discount for lack of marketability of 15% and 25% was applied to the IPO and non-IPO
scenarios, respectively.

 March 31, 2018 Valuation

The fair value of the Company’s common stock of $1.46 per share as of March 31, 2018 was determined with the assistance of an
independent third-party valuation firm. This valuation was used for the retrospective fair value assessment of the stock option grants on March 16, 2018. This valuation utilized the hybrid method, which considered the value of the
Company’s common stock in both IPO and non-IPO scenarios. The present value of the Company’s common stock in an IPO scenario was calculated based on metrics observed from then-recent IPOs in the
biotechnology industry. The value of the Company’s common stock in a non-IPO scenario was calculated using the OPM. The valuation assumed a 50% probability of an IPO and a 50% probability of a non-IPO scenario. A discount for lack of marketability of 12% and 25% was applied to the IPO and non-IPO scenarios, respectively.

The weighting attributed to the IPO scenarios in each of the valuations above reflected assessments as to the likelihood of an IPO and the
uncertainty concerning whether investors might be receptive to making an investment in the Company. The Company also considered macroeconomic and overall market conditions, including the Company’s subjective assessment of market conditions for
IPOs of companies similarly situated to the Company and the Company’s subjective assessment as to the likelihood of successfully executing an IPO in the coming months, among other factors.

The Company respectfully requests that the Staff return to us this letter and the information provided pursuant to Exhibits A, B
and C pursuant to Rule 418 of the Securities Act of 1933, as amended, once the Staff has completed its review. We have provided a self-

 Ms. Dorrie Yale

Securities and Exchange Commission

 June 1, 2018

 Page
 5

 addressed stamped envelope for this purpose. In addition, the Company requests confidential treatment under
17 C.F.R. § 200.83 (1992) for this letter and the information provided pursuant to Exhibits A, B and C of this letter and has submitted a separate request for confidential treatment in accordance
therewith to the Commission’s Office of Freedom and Information Privacy Act Operations.

 If you have any questions or comments
regarding the foregoing, or if there is any additional information that we might provide to assist the Staff’s review, please contact the undersigned at (617) 570-1483.

Sincerely,

/s/ James Xu

James Xu

Goodwin Procter LLP

cc:
Rolf Sundwall, United States Securities and Exchange Commission

 Jim Rosenberg,
United States Securities and Exchange Commission

 Suzanne Hayes, United States Securities and Exchange Commission

Geoff MacKay, AVROBIO, Inc.

Katina Dorton, AVROBIO, Inc.

Arthur R. McGivern, Goodwin Procter LLP

 Ms. Dorrie Yale

Securities and Exchange Commission

 June 1, 2018

 Page
 6

 Exhibit A

The Company supplementally advises the Staff that the estimated price range for the common stock in the Company’s proposed initial public
offering (“IPO”) is between $[***] to $[***] per share. Please note that while the Company expects to effect a reverse stock split prior to the initial public offering, the price range above does not reflect the impact of the anticipated
reverse stock split. This estimated bona fide price range is based on a number of factors, including the prevailing market conditions and estimates of the Company’s business potential, the general condition of the securities market, the
recent market prices of, and the demand for, publicly-traded common stock of generally comparable companies and preliminary discussions with the underwriters for this offering regarding potential valuations of the Company. The actual bona
fide price range to be included in a subsequent amendment to the Registration Statement has not yet been determined and remains subject to adjustment based on factors outside of the Company’s control. However, the Company believes that the
actual bona fide price range will be within this estimated bona fide price range. In addition, the actual price range to be included in such amendment will comply with the Staff’s interpretation regarding the parameters of a
bona fide price range.

 With respect to the price range set forth above, the Company notes that, as is typical in initial public
offerings, the estimated price range for its offering was not derived using a formal determination of fair value, but was determined based upon discussions between the Company and the underwriters. Among the factors considered in setting the
estimated range were prevailing market conditions, estimates of the Company’s business potential, progress in its research and development programs and developments in its business, the general condition of the securities market and the market
prices of, and demand for, publicly-traded common stock of generally comparable companies.

 In addition, the Company believes the
difference in value reflected between the estimated price range and the determination of the fair value of its common stock as of March 31, 2018 is primarily the result of the following factors:

•

Significant progress continued in the ongoing investigator-sponsored Phase 1 clinical trial of AVR-RD-01 for Fabry disease. For example,
the Company received twelve-month enzyme activity and vector copy number (“VCN”) data as well as 14-month bone marrow clone and VCN data from the first patient in the trial, and three-month
enzyme activity and VCN data from the second patient in the trial. In addition, consent was received from the third patient to participate in the trial.

•

 Significant progress was also made in the Company’s planned Phase 2 clinical trial of AVR-RD-01 for Fabry disease. For example, following approval of the clinical trial application (“CTA”) from Health Canada in the fourth quarter of 2017, the
Company initiated and opened centers in two participating countries. The Company also

 Ms. Dorrie Yale

Securities and Exchange Commission

 June 1, 2018

 Page
 7

determined the timeframe for the planned commencement of dosing in this trial, which is expected to occur in [***].

•

The outcome from the Company’s pre-CTA meeting with Health Canada related to its Gaucher program was positive, and the Company completed the data package for chemistry,
manufacturing and controls, and pre-clinical and clinical. The Company continues to prepare to file its CTA and commence dosing in its planned clinical trial for the Gaucher program.

•

The Company advanced the readiness of its manufacturin

CORRESP
1
filename1.htm

SEC Letter

 Goodwin Procter LLP

100 Northern Avenue

 Boston, MA 02210

 goodwinlaw.com

+1 617 570 1000

 May 25, 2018

VIA EDGAR AND FEDERAL EXPRESS

 United States
Securities and Exchange Commission

 Division of Corporation Finance

Mail Stop 4720

 100 F Street, N.E.

Washington, D.C. 20549

 Attention: Dorrie Yale

Re:
AVROBIO, Inc.

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

Submitted May 11, 2018

CIK No. 0001681087

 Dear Ms. Yale:

This letter is submitted on behalf of AVROBIO, Inc. (the “Company”) in response to the comments of the staff of the Division
of Corporation Finance (the “Staff”) of the U.S. Securities and Exchange Commission (the “Commission”) with respect to Amendment No. 1 to the Draft Registration Statement on Form S-1 confidentially submitted on May 11, 2018 (“Amendment No. 1”), as set forth in your letter dated May 23, 2018 addressed to Geoffrey MacKay, President and Chief
Executive Officer of the Company (the “Comment Letter”). The Company is concurrently publicly filing its Registration Statement on Form S-1 (the “Registration Statement”),
which includes changes to reflect responses to the Staff’s comments.

 For reference purposes, the text of the Comment Letter has been
reproduced herein with responses below each numbered comment. For your convenience, we have italicized the reproduced Staff comments from the Comment Letter. Unless otherwise indicated, page references in the descriptions of the Staff’s
comments refer to Amendment No. 1, and page references in the responses refer to the Registration Statement. All capitalized terms used and not otherwise defined herein shall have the meanings set forth in the Registration Statement.

The responses provided herein are based upon information provided to Goodwin Procter LLP by the Company. In addition to submitting this letter
via EDGAR, we are sending via Federal Express four (4) copies of each of this letter and Amendment No. 1 (marked to show changes from Amendment No. 1).

Amendment No. 1 to Draft Registration Statement on Form S-1 Submitted on
May 11, 2018

 Prospectus Summary, page 1

COMMENT NO. 1: We acknowledge your revised disclosures in response to prior comment 1. However, please further revise your disclosure to remove the
statement that lasting benefits have been observed in ongoing clinical trials of third parties. If you wish to keep the statement in the Business section, please expand your disclosure to specifically discuss results from those third party trials.

 RESPONSE: The Company respectfully advises the Staff that it has revised its disclosures on pages 1, 87 and 91 in response to the Staff’s
comment.

 Business

Overview, page 87

 COMMENT NO. 2: Please expand your
revised disclosure in the second paragraph of this section to explain the term “clinically significant.”

 RESPONSE: The Company respectfully
advises the Staff that it has revised its disclosures on page 87 in response to the Staff’s comment.

 If you should have any
questions concerning the enclosed matters, please contact the undersigned at (617) 570-1483.

 Sincerely,

/s/ James Xu

 James Xu, Esq.

 Goodwin Procter
LLP

cc:
Geoff MacKay, AVROBIO, Inc.

 Katina Dorton, AVROBIO, Inc.

Arthur R. McGivern, Esq., Goodwin Procter LLP

May 23, 2018
Geoff MacKay
President and Chief Executive Officer
AVROBIO, Inc.
One Kendall Square
Building 300, Suite 201
Cambridge, MA 02139
Re:AVROBIO, Inc.
Amendment No. 1 to Draft Registration Statement on Form S-1
Submitted May 11, 2018
CIK No. 0001681087
Dear Mr. MacKay:
            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.
Amendment No. 1 to Draft Registration Statement on Form S-1
Prospectus Summary, page 1
1.We acknowledge your revised disclosures in response to prior comment 1.  However,
please further revise your disclosure to remove the statement that lasting benefits have
been observed in ongoing clinical trials of third parties.  If you wish to keep the statement
in the Business section, please expand your disclosure to specifically discuss results from
those third party trials.

 FirstName LastNameGeoff MacKay
 Comapany NameAVROBIO, Inc.
 May 23, 2018 Page 2
 FirstName LastName
Geoff MacKay
AVROBIO, Inc.
May 23, 2018
Page 2
Business
Overview, page 87
2.Please expand your revised disclosure in the second paragraph of this section to explain
the term "clinically significant."
            You may contact Rolf Sundwall at 202-551-3105 or Jim Rosenberg at 202-551-3679 if
you have questions regarding comments on the financial statements and related matters.  Please
contact Dorrie Yale at 202-551-8776 or Suzanne Hayes at 202-551-3675 with any other
questions.
Division of Corporation Finance
Office of Healthcare & Insurance
cc:       James Xu

May 4, 2018
Geoff MacKay
President and Chief Executive Officer
AVROBIO, Inc.
One Kendall Square
Building 300, Suite 201
Cambridge, MA 02139
Re:AVROBIO, Inc.
Draft Registration Statement on Form F-1
Submitted April 6, 2018
CIK No. 0001681087
Dear Mr. MacKay:
            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, page 1
1.We note your statements in the penultimate paragraph and on page 84 that lentiviral-based
gene therapy has demonstrated durable effects and safety in ongoing clinical trials.
As safety and efficacy determinations are solely within the FDA’s authority and they
continue to be evaluated throughout all phases of clinical trials, please remove
these statements.In the Business section, you may present objective data resulting from
your trials, such as Plasma AGA Activity (nmol//hr.ml) without including conclusions

 FirstName LastNameGeoff MacKay
 Comapany NameAVROBIO, Inc.
 June 16, 2017 Page 2
 FirstName LastNameGeoff MacKay
AVROBIO, Inc.
May 4, 2018
Page 2
relating to efficacy, such as that the program has demonstrated promising results to date..
2.Please limit the summary discussion of your ongoing clinical trial to a discussion of the
trial endpoint(s) and any serious adverse events.  Additionally explain that patients in this
Phase 1 trial for Fabry diseases are also receiving ERT and clarify that enrollment for this
Phase I trial is still ongoing.
3.We note that you have an ongoing Phase I clinical trial for your most advanced product
candidate, AVR-RD-01, and anticipate commencing a Phase 2 trial in mid-2018.  Please
revise your Pipeline table to present Phase 1 and Phase 2 trials in separate columns or
explain why you believe the current presentation is appropriate.
Risks Associated with Our Business, page 4
4.Please expand the disclosure in your penultimate bullet to explain that you are aware of
issued patents in the U.S. that cover the lentiviral vectors used in the manufacture of your
product candidates, and that you do not own or license any patents or patent applications
covering AVR-RD-01 or AVR-RD-02, as you explain in your risk factors on pages 40 and
42.
Implications of Being an Emerging Growth Company, page 5
5.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.
Management's Discussion and Analysis of Financial Condition and Results of Operations
Critical Accounting Policies and Significant Judgments and Estimates
Stock-Based Compensation
Determination of the Fair Value of Common Stock, page 80
6.Once you have an estimated offering price or range, please explain to us the reasons for
any differences between the recent valuations of your common stock leading up to the
IPO and the estimated offering price. This information will help facilitate our review of
your accounting for equity issuances including stock compensation and beneficial
conversion features.
Business
Our Approach, page 86
7.Please expand the narrative disclosure relating to the two charts on page 89 to explain
what the bottom axis represents, and the significance of the right axis.
AVR-RD-01, Our Gene Therapy for Fabry Disease, page 91

 FirstName LastNameGeoff MacKay
 Comapany NameAVROBIO, Inc.
 June 16, 2017 Page 3
 FirstName LastName
Geoff MacKay
AVROBIO, Inc.
May 4, 2018
Page 3
8.Please revise your description of your Phase 1 trial for AVR-RD-01 on page 93 to
describe the primary endpoints of safety and tolerability in terms of the objective data
points you are using.  Please also disclose the range of plasma AGA enzyme activity for
males with classic Fabry disease, and clarify whether the two patients that have been
dosed are male.
9.Please explain the significance of the p-values at the top of the charts on pages 97, 99, and
103, and also discuss how these values relate to the FDA’s evidentiary standards of
efficacy.
Intellectual Property and Other Barriers to Entry, page 105
10.We note your statement on page 106 that your royalty obligations under the UHN
agreement expire on a licensed product-by-licensed-product and country-by-country basis
upon the latest to occur of several events, one of which is the expiration or termination of
the last valid claim in such country.  Please revise to clarify the types of claims this refers
to and when these claims are expected to expire.  Please also revise your disclosure
regarding the BioMarin agreement to clarify the term of your royalty obligations.
General
11.Please provide us proofs of all graphics, visual or photographic information you
will provide in the printed prospectus prior to its use, for example in a preliminary
prospectus.  Please note that we may have comments regarding this material.
12.Your statements in the last paragraph under the Table of Contents that you have not
independently verified any third party market data and other statistical information may
imply an inappropriate disclaimer of responsibility with respect to the third party
information.  Please either delete these statements or specifically state that you are liable
for such information.
            You may contact Rolf Sundwall at 202-551-3105 or Jim Rosenberg at 202-551-3679 if
you have questions regarding comments on the financial statements and related matters.  Please
contact Dorrie Yale at 202-551-8776 or Suzanne Hayes at 202-551-3675 with any other
questions.
Division of Corporation Finance
Office of Healthcare & Insurance