United States securities and exchange commission logo May 5, 2021 William Clark President and Chief Executive Officer GENOCEA BIOSCIENCES, INC. 100 Acorn Park Drive, 5th Floor Cambridge, MA 02140 Re: GENOCEA BIOSCIENCES, INC. Registration Statement on Form S-3 Filed April 29, 2021 File No. 333-255610 Dear Mr. Clark: 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 Jeffrey Gabor at 202-551-2544 with any questions. Sincerely, Division of Corporation Finance Office of Life Sciences cc: Marc A. Rubenstein, Esq.