United States securities and exchange commission logo July 20, 2023 Nassim Usman, Ph.D. President and Chief Executive Officer Catalyst Biosciences, Inc. 611 Gateway Blvd Suite 120 South San Francisco, CA 94080 Re: Catalyst Biosciences, Inc. Preliminary Proxy Statement on Schedule 14A Filed March 30, 2023 File No. 000-51173 Dear Nassim Usman: We have completed our review of your filing. 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. Sincerely, Division of Corporation Finance Office of Life Sciences cc: Stephen B. Thau, Esq.