United States securities and exchange commission logo





                           June 19, 2020

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

                                                        Re: Pandion
Therapeutics Holdco LLC
                                                            Draft Registration
Statement on Form S-1
                                                            Filed May 22, 2020
                                                            CIK No. 0001807901

       Dear Dr. Kakkar:

              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 submitted May 22, 2020

       Prospectus Summary
       Overview, page 1

   1.                                                   We note your statements
throughout your filing that you believe your product candidate,
                                                        PT101, may potentially
be best-in-class or have best-in-class selectivity for Treg cells
                                                        over other types of
immune cells. Given the early stage of development, and your
                                                        statements that your
approach to discovery and development is unproven, these statements
                                                        are overly speculative
and inappropriate. Please remove these statements from the
                                                        descriptions of your
product candidates.
       Our Programs, page 3
 Rahul Kakkar, MD
FirstName LastNameRahul Kakkar, MD
Pandion Therapeutics Holdco LLC
Comapany NamePandion Therapeutics Holdco LLC
June 19, 2020
June 19, 2020 Page 2
Page 2
FirstName LastName
2.       Please revise your table to include target indications for all product
candidates included in
         the table and explain the symbols included in the "Location" column.
3.       With respect to your table on pages 3 and 114, it appears that your
identified product
         candidates are part of the research programs. Therefore, some of the
items appear
         redundant. For example, we note PT001 and PT002 are all discussed
together with the
         description of your tether programs. To the extent these are unique
material product
         candidates and programs, please discuss them individually. Product
candidates and
         programs that are not material to your current operations should not
be included in your
         table. These items may be more appropriate for discussion in the
Business section than in
         the Summary.
4.       Please delete the line item titled "New Effectors" from the table. If
these programs
         include material programs that are not otherwise depicted you can
include them
         separately. Alternatively, you may discuss additional programs in the
Business section.
Risks Associated with Our Business, page 5

5.       Please expand your disclosure in the last bullet point to highlight
the known risks
         associated with certain European and other foreign patents and
applications owned by
         third parties that may inhibit your lead product candidate, PT101,
consistent with your
         discussion on pages 35 and 41.
Implications of Being an Emerging Growth Company, page 8

6.       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.
Risk Factors, page 13

7.       We note your disclosure on page 73 and on page 186 that your exclusive
forum provision
         does not apply to actions arising under the Securities Act or the
Exchange Act. Please tell
         us how you will inform investors in future filings that the provision
does not apply to any
         actions arising under the Securities Act or Exchange Act.
Use of Proceeds, page 76

8.       Refer to the first and second bullet points. Please clarify whether or
not you expect to
         complete the planned Phase 1b/2a clinical trial for PT101 and the
IND-enabling studies
         for PT627 and PT001 with the proceeds of the offering. Please specify
how far in the
         development of each of your identified preclinical candidates and your
various discovery
         programs you expect to reach with the proceeds of the offering. To the
extent any
         material amounts of other funds are necessary to accomplish the
specified purposes, state
         the amounts and sources of other funds needed for each specified
purpose and the
 Rahul Kakkar, MD
FirstName LastNameRahul Kakkar, MD
Pandion Therapeutics Holdco LLC
Comapany NamePandion Therapeutics Holdco LLC
June 19, 2020
June 19, 2020 Page 3
Page 3
FirstName LastName
         sources. Refer to Instruction 3 to Item 504 of Regulation S-K.
Management's Discussion and Analysis of Financial Condition and Results of
Operations
Critical Accounting Policies and Significant Judgments and Estimates
Revenue Recognition, page 101

9.       We note from your disclosures on page F-48 that the contractual term
under the Astellas
         Agreement is five years but you have estimated that your research and
development
         commitments will be substantially completed by the end of 2022. Please
revise your
         disclosure to clearly explain the significant factors management
considered in determining
         the term of your performance obligation.
Equity-based Compensation, page 102

10.      Once you have an estimated offering price or range, please explain to
us how you
         determined the fair value of the common stock underlying your equity
issuances and 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.
Business
Our Focus: A Network-Based Conceptualization of the Immune System, page 109

11.      We note your reference to a "graphic below" in both your description
on "Node:
         Inhibitory Checkpoints (i.e. PD-1)" and "Node: Soluble Mediators (i.e.
CD39)." Please
         revise to make clear the specific graphic you are referencing by
either including the
         graphic directly below or label and identify the figure accordingly.
Our Programs, page 114

12.      Please revise the text accompanying the charts on page 123 to explain
exactly what
         the Y axis in each chart represents and how it is calculated. Please
also revise the chart on
         page 123 so that the text is legible.
Intellectual Property, page 128

13.      We note your risk factor discussion on pages 35 and 41 regarding
various third party
         patents and patent applications that may affect your product
candidates. To the extent that
         any such third party patents or applications may have a material
effect on any of your
         product candidates, please expand your disclosure here to discuss.
License and Collaboration Agreements, page 129

14.      Please expand your discussion of the collaboration and license
agreement with Astellas
         Pharma Inc. to quantify and clarify the duration of the agreement,
consistent with your
         disclosure on page F-28.
 Rahul Kakkar, MD
Pandion Therapeutics Holdco LLC
June 19, 2020
Page 4
15.   We note your disclosed that you are not permitted to use tether
identified in the research
      plan during the term of the Astellas agreement. Please disclose the
identity of the tethers
      that are part of the research plan or explain why you believe this
prohibition does not
      materially restrict your operations.
Financial Statements
Consolidated Balance Sheets, page F-3

16.   We note that your redeemable convertible preferred stock and shares are
included in
      "Total liabilities and members'/stockholders' deficit" even though these
issuances have
      been classified as mezzanine equity. Please revise this line item to
clearly indicate that it
      also includes amounts classified as mezzanine equity. Refer to Rule
5-02(27)(d) of
      Regulation S-X.
Note 8 - Commitments and Contingencies, page F-21

17.   We note the disclosure of your agreements with Distributed Bio on page
105. Please tell
      us why you have not provided financial statement footnote disclosure of
the material
      terms of these agreements under ASC 440.
Note 15 - Net Loss Per Share
Unaudited Pro Forma Net Loss Per Share, page F-31

18.   We note that incentive shares were excluded from your pro forma weighted
average
      shares outstanding. However, in your table, the adjustment indicates that
convertible
      preferred shares and incentive shares are included in pro forma weighted
average shares
      outstanding. Please clarify how incentive shares were treated in the pro
forma calculation.
       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
June 19, 2020 Page 4
cc:       Lia Der Marderosian
FirstName LastName