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                              July 13, 2021

       David Southwell
       Chief Executive Officer
       TScan Therapeutics, Inc.
       830 Winter Street
       Waltham, MA 02451

                                                        Re: TScan Therapeutics,
Inc.
                                                            Amendment No. 4 to
Registration Statement on Form S-1
                                                            Filed July 12, 2021
                                                            File No. 333-255491

       Dear Mr. Southwell:

             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.
Unless we note
       otherwise, our references to prior comments are to comments in our May
3, 2021 letter.

       Amendment No. 4 to Registration Statement on Form S-1 filed July 12,
2021

       Dilution , page 98

   1.                                                   Please explain to us
how you calculated your historical net tangible book value (deficit) of
                                                        $49.9 million. Please
also explain how the 5,162,953 of non-voting common shares to be
                                                        issued upon the
conversion of your preferred stock was considered in your calculation of
                                                        pro forma net tangible
book value on a per share basis.
       ImmunoBank - Flexible Content for Diverse Platform, page 151

   2.                                                   We note your disclosure
on page 151 regarding your competitors who are also focused on
                                                        T-cell engineering.
Please expand your disclosure in your prospectus, where and as
                                                        appropriate (including
in the Competition section on page 158), to include disclosure of
 David Southwell
TScan Therapeutics, Inc.
July 13, 2021
Page 2
      the competitors specified in this section.
       You may contact Tara Harkins at 202-551-3639 or Angela Connell at
202-551-3426 if
you have questions regarding comments on the financial statements and related
matters. Please
contact Jane Park at 202-551-7439 or Tim Buchmiller at 202-551-3635 with any
other questions.



                                                         Sincerely,
FirstName LastNameDavid Southwell
                                                         Division of
Corporation Finance
Comapany NameTScan Therapeutics, Inc.
                                                         Office of Life
Sciences
July 13, 2021 Page 2
cc:       Timothy H. Ehrlich, Esq.
FirstName LastName