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                            July 7, 2020

       Rahul Kakkar, MD
       Chief Executive Officer
       Pandion Therapeutics Holdco LLC
       134 Coolidge Avenue
       Watertown, Massachusetts 02472

                                                        Re: Pandion
Therapeutics Holdco LLC
                                                            Registration
Statement on Form S-1
                                                            Filed June 26, 2020
                                                            File No. 333-239500

       Dear Dr. Kakkar:

              We have reviewed your 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 filed June 26, 2020

       Management's Discussion and Analysis of Financial Condition and Results
of Operations
       Critical Accounting Policies and Significant Judgments and Estimates
       Revenue Recognition, page 103

   1.                                                   We note your response
and revised disclosure in response to comment 9. Please explain
                                                        to us why you believe
the research and development commitments will be completed in
                                                        approximately 3 years
given that the research term in the contract is for a period of 5
                                                        years.
 Rahul Kakkar, MD
Pandion Therapeutics Holdco LLC
July 7, 2020
Page 2
License and Collaboration Agreement with Astellas Pharma, page 131

2.    Please revise your discussion to quantify the one time milestone payment
related to the
      first dosing in a GLP-toxicology study or otherwise include this
potential payment in the
      aggregate milestones presented.
        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.

       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.

       You may contact Eric Atallah at 202-551-3663 or Lynn Dicker at
202-551-3616 if you
have questions regarding comments on the financial statements and related
matters. Please
contact Jason L. Drory at 202-551-8342 or Suzanne Hayes at 202-551-3675 with
any other
questions.



                                                           Sincerely,
FirstName LastNameRahul Kakkar, MD
                                                           Division of
Corporation Finance
Comapany NamePandion Therapeutics Holdco LLC
                                                           Office of Life
Sciences
July 7, 2020 Page 2
cc:       Lia Der Marderosian
FirstName LastName