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                          March 9, 2021

       Nassim Usman, Ph.D.
       Chief Executive Officer
       Catalyst Biosciences, Inc.
       611 Gateway Blvd. Suite 710
       South San Francisco, CA 94080

                                                        Re: Catalyst
Biosciences, Inc.
                                                            Registration
Statement on Form S-3
                                                            Filed March 4, 2021
                                                            File No. 333-253874

       Dear Dr. Usman:

              This is to advise you that we have not reviewed and will not
review your registration
       statement.

               Please refer to Rules 460 and 461 regarding requests for
acceleration. 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.

                                                        Please contact Jason
Drory at 202-551-8342 with any questions.




                          Sincerely,


                          Division of Corporation Finance

                          Office of Life Sciences
       cc:                                              Stephen B. Thau, Esq.