SecProbe.io

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