 BEVERLY HILLS, Calif., May 12, 2021 PRNewswire -- GT Biopharma, Inc. NASDAQ: GTBP, a clinical stage immuno-oncology company focused on developing innovative therapeutics based on the Companys proprietary NK cell engager TriKETM protein biologic technology platform, is pleased to provide an update concerning the commencement of the GTB-3550 TriKETM monotherapy Phase 2 clinical trial, and certain of its solid tumor targeting TriKETM product candidates. 