Exhibit 23.2

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in the Prospectus constituting a part of this Registration Statement on Form S-8 pertaining to the Mateon Therapeutics, Inc. 2017 Equity Incentive Plan, of our report dated March 30, 2017 (which report expresses an unqualified opinion and includes an explanatory paragraph expressing substantial doubt about the Company’s ability to continue as a going concern), relating to the financial statements of Mateon Therapeutics, Inc. appearing in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016.

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

/s/ OUM & CO. LLP

San Francisco, California

March 30, 2017