UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2021 Commission File Number: 001-40023 GT BIOPHARMA, INC. (Exact name of Registrant as specified in its charter) (State or other jurisdiction of incorporation or organization) Delaware 94-1620407 (I.R.S. Employer Identification No.) 8000 Marina Blvd. Suite 100 Brisbane, CA 94005 (Address of principal exec ...