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                          August 14, 2020

       Susan M. Molineaux, Ph.D.
       President and Chief Executive Officer
       Calithera Biosciences, Inc.
       343 Oyster Point Blvd., Suite 200
       South San Francisco, CA 94080

                                                        Re: Calithera
Biosciences, Inc.
                                                            Registration
Statement on Form S-3
                                                            Filed August 10,
2020
                                                            File No. 333-243731

       Dear Dr. Molineaux:

              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 Deanna
Virginio at 202-551-4530 with any questions.




                          Sincerely,


                          Division of Corporation Finance

                          Office of Life Sciences
       cc:                                              Seth J. Gottlieb, Esq.