Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

Acer Therapeutics Inc.

Newton, Massachusetts

We hereby consent to the incorporation by reference in the Prospectus constituting a part of this Amendment No. 1 to the Registration Statement (No. 333-238192) of our report dated March 18, 2020, relating to the consolidated financial statements of Acer Therapeutics Inc. appearing in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. Our report contains an explanatory paragraph regarding the Company’s ability to continue as a going concern.

We also consent to the reference to us under the caption “Experts” in the Prospectus.

/s/ BDO USA, LLP

Boston, Massachusetts

June 1, 2020