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                              September 15, 2021

       R. Steven Hicks
       Chief Executive Officer
       Capstar Special Purpose Acquisition Corp.
       405 West 14th Street
       Austin, TX 78701

                                                        Re: Capstar Special
Purpose Acquisition Corp.
                                                            Registration
Statement on Form S-4
                                                            Filed August 10,
2021
                                                            File No. 333-258693

       Dear Mr. Hicks:

              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-4 filed August 10, 2021

       Market and Industry Data, page iii

   1.                                                   Your statements
regarding information in the document provided by third-party sources,
                                                        or based on information
from third-party sources, inappropriately implies you are not
                                                        responsible for the
disclosure in the prospectus. Revise to clarify you are responsible for
                                                        all disclosure in the
prospectus.
       Summary of the Proxy Statement/Prospectus, page 22

   2.                                                   Please revise the
Summary disclosure concerning Gelesis to highlight the going concern
                                                        determinations
referenced on page 192.
   3.                                                   Please revise the
disclosure on page 23 to explain briefly how the de novo classification
 R. Steven Hicks
FirstName LastNameR.
                PurposeSteven HicksCorp.
Capstar Special        Acquisition
Comapany 15,
September  NameCapstar
               2021     Special Purpose Acquisition Corp.
September
Page 2     15, 2021 Page 2
FirstName LastName
         differs from the PMA and 510(k) pathways as it relates to
determinations concerning
         safety and efficacy.
Summary Risk Factors, page 29

4.       Disclose the material risks to unaffiliated investors presented by
taking the company
         public through a merger rather than an underwritten offering. These
risks could include
         the absence of due diligence conducted by an underwriter that would be
subject to liability
         for any material misstatements or omissions in a registration
statement.
Background to the Business Combination, page 98

5.       With reference to the disclosure on page 100, please revise to discuss
who introduced you
         to Gelesis and the individuals and parties who were involved in the
initial communications
         and negotiations.
6.       Please substantially revise to discuss the    preliminary discussions
  and negotiations
         concerning material terms of the business combination, particularly as
it relates to
         valuation of Gelesis. For instance, and without limitation, we note
that Background
         section is silent with respect to the valuations discussed/proposed
during the February 25
         to April 15 timeframe. Please be sure to indicate which party first
presented a valuation
         figure and discuss each counterproposal so that investors can
understand how this term
         was negotiated and whether the valuation moved materially during this
period. Discuss
         the basis or bases presented in support of each valuation proposed.
7.       Please revise to discuss and explain the financial model or models
developed by each
         party or the parties. Discuss all material inputs and assumptions
underlying the model or
         models. Disclose forecasts that Gelesis or advisors presented to CPSR
 s management or
         Board, or advise. In this regard, we note that the implied equity
value ascribed to Gelelis
         is based on forecasted revenue and gross profit.
8.       Revise to discuss the material terms negotiated during the PIPE
Financing so that
         investors can understand the issues that mattered to the parties and
how the proposed
         terms changed during the course of the negotiations.
The Board's Reasons for the Business Combination, page 105

9.       Please revise the disclosure on page 106 to explain how the peer sets
were developed.
          Explain the bases that the Board used to determine that the six
identified companies were
         the most comparable to Gelesis. Explain whether the Board considered
the valuations of
         any companies in the weight management industry.
10.      Present the market capitalization, enterprise value, implied valuation
multiples and other
         relevant financial measures for each of the six peer companies so that
investors can
         understand how Gelesis represented an attractive valuation relative to
this peer set. Also,
         clarify the rationale and basis for using projected 2023 revenue,
projected 2023 gross
         profit and the 2.2x and 3.4x multiples.
 R. Steven Hicks
Capstar Special Purpose Acquisition Corp.
September 15, 2021
Page 3
Interests of CPSR's Directors and Executive Officers in the Business
Combination, page 108

11.      Please expand your disclosure here to quantify the aggregate dollar
amount and describe
         the nature of what the CPSR sponsor and its affiliates have at risk
that depends on
         completion of a business combination. Include the current value of
securities held, loans
         extended, fees due, out-of-pocket expenses and other items for which
the sponsor and its
         affiliates are awaiting reimbursement. Provide similar disclosure for
the company   s
         officers and directors, if material. Further, please clarify if the
CPSR sponsor and its
         affiliates can earn a positive rate of return on their investment,
even if other CPSR
         shareholders experience a negative rate of return in the post-business
combination
         company. Please also highlight this information in your Questions and
Answers and/or
         Summary discussion.
U.S. Federal Income Considerations, page 130

12.      Please have counsel provide a tax opinion addressing the tax
consequences to U.S. holders
         of CPSR common stock who exercise redemption rights and who hold
shares at the time
         of the Business Combination. The tax opinion should address and
express a conclusion for
         each material federal tax consequence. For additional guidance
concerning assumptions
         and opinions subject to uncertainty, refer to Staff Legal Bulletin No.
19.
Information about Gelesis, page 165

13.      Please revise to disclose the operating plan for the business in the
coming few years as
         well as the intended uses of the proceeds raised through the merger
and PIPE financings.
         State the principal purposes and the approximate amount intended to be
used for each
         such purpose.
14.      With reference to the risk factors on page 39, please revise to
identify the jurisdictions, as
         applicable, where state medical boards have established rules or
interpreted existing rules
         in a manner that limit or restrict the ability of Gelesis    qualified
distributors to use
         telehealth services in connection with providing patients with access
to Plenity.
15.      We note the disclosure on page 169 that during the Beta Launch Gelesis
achieved a 90-
         95% physician    grant rate    among people with a BMI 25-40 seeking a
prescription
         through telehealth. Please revise to explain the term    grant rate.
 Disclose the grant rate
         for patients with a BMI under and above this BMI range.
16.    With reference to your disclosure on pages 178-179, please discuss
whether you have trial
       results that extend beyond 24 weeks, and if not, whether any such
studies are planned.
FirstName LastNameR. Steven Hicks
       Discuss, as applicable, whether the lack of longer term data impacts
commercialization of
Comapany   NameCapstar
       Plenity  for the BMISpecial
                            of 25    Purpose Acquisition
                                    40 indication       Corp. longer term data
will be required to
                                                  and whether
       receive
September  15, regulatory
                2021 Page clearance/approval
                           3                  for the additional indications
that you are targeting.
FirstName LastName
 R. Steven Hicks
FirstName LastNameR.
                PurposeSteven HicksCorp.
Capstar Special        Acquisition
Comapany 15,
September  NameCapstar
               2021     Special Purpose Acquisition Corp.
September
Page 4     15, 2021 Page 4
FirstName LastName

Key Business Metrics, page 195

17.      Please address the following:
             You state that you define "members" as the number of consumers who
have begun
             their weight loss journey with Plenity and that it includes the
cumulative number of
             both recurring and non-recurring consumers as of the respective
reporting date. Tell
             us how you considered providing a breakdown of recurring versus
non-recurring
             members.
             The sentence preceding the table indicates that all these metrics
are in thousands.
             Tell us whether the number of members and number of units sold are
in thousands
             like the dollar amounts. If not, please revise your presentation
accordingly.
             Further, tell us how the cumulative members number of 32,900
thousand presented
             here reconciles to your statement on page 169 that "over 50,000
members have
             started their weight loss journey with Plenity sense its Beta
launch."
             Revise your discussion of revenues within your Results of
Operations sections on
             pages 200 and 202 to present a rate/volume analysis, providing us
with a
             supplemental reconciliation between that disclosure and your
business metrics here.
Results of Operations, page 200

18.      Revise your discussions of research and development expense to provide
a breakdown of
         these expenses by the type of expense included. To the extent you
track your research and
         development expense on a product candidate basis, separately quantify
such expenses by
         product candidate. To the extent you do not track your research and
development
         expenses on a product candidate basis, disclose that fact.
Exhibits

19.      Please file the distribution agreements with Roman Health Pharmacy LLC
and
         GoGoMeds as exhibits.
20.      Please file the strategic partnership agreement with China Medical
System Holdings
         Limited as an exhibit.
        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.
 R. Steven Hicks
Capstar Special Purpose Acquisition Corp.
September 15, 2021
Page 5




        You may contact Frank Wyman at (202) 551-3660 and Kevin Vaughn at (202)
551-3494
if you have questions regarding comments on the financial statements and
related
matters. Please contact Jordan Nimitz at (202) 551-5831 or Joe McCann at (202)
551-6262 with
any other questions.



                                                         Sincerely,
FirstName LastNameR. Steven Hicks
                                                       Division of Corporation
Finance
Comapany NameCapstar Special Purpose Acquisition Corp.
                                                       Office of Life Sciences
September 15, 2021 Page 5
cc:       Christopher S. Auguste
FirstName LastName