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GT Biopharma Announces First Patient Dosed in Phase 1 Trial of GTB-5550, a B7-H3-Targeted Natural Killer (NK) Cell Engager for Solid Tumors
GTB-5550 is now the 3rd TriKE® to enter the clinic and an expansion into a broader solid tumor opportunity, with the Phase 1 trial likely to focus on prostate
About this update from Gt Biopharma, Inc.
[{"type":"text","content":"GTB-5550 is now the 3rd TriKE® to enter the clinic and an expansion into a broader solid tumor opportunity, with the Phase 1 trial likely to focus on prostate cancer patients during the dose escalation phase Company anticipates providing updates in 2H 2026 as enrollment progresses through dose escalation cohorts SAN FRANCISCO, CALIFORNIA, May 14, 2026 (GLOBE NEWSWIRE) -- GT Biopharma, Inc. (the “Company”) (NASDAQ: GTBP), a clinical stage immuno-oncology company focused on developing innovative therapeutics based on the Company's proprietary TriKE® natural killer (NK) cell engager platform, today announced that the first patient was dosed in a Phase 1 dose escalation basket trial evaluating GTB-5550, its B7-H3-targeted natural killer (NK) cell engager for solid tumors expressing B7-H3. “Dosing the first patient in our GTB-5550 Phase 1 trial is a pivotal milestone for GT Biopharma and represents the natural evolution of our TriKE® platform into the broader opportunity of treating patients with a variety of solid tumors. The ongoing Phase 1 progress with GTB-3650 in hematologic malignancies now gives us the confidence to advance the platform with GTB-5550 to target B7-H3, which is broadly expressed across many of the most common and difficult-to-treat solid tumor cancers. We look forward to providing updates on the trial's progress throughout the second half of 2026.”, said Michael Breen, Executive Chairman and Chief Executive Officer of GT Biopharma. The Phase 1 trial with GTB-5550 will be the first nanobody TriKE® tested with more patient-friendly subcutaneous dosing. The Phase 1a dose escalation portion of the trial will focus primarily on enrolling prostate cancer patients and evaluate up to 6 dose levels to identify the maximum tolerated dose (MTD). After the dose escalation phase, the Phase 1b expansion component will enroll patients with up to 7 different tumor types (castration-resistant prostate cancer, ovarian cancer, breast cancer, head and neck cancer, non-small cell lung cancer, pancreatic cancer, and bladder cancer) and further evaluate its safety, tolerability and preliminary anti-tumor activity. “Patients with metastatic castration-resistant prostate cancer have B7-H3 expressed in over 90% of tumors and PSA can serve as an early biomarker of therapeutic activity. We look forward to evaluating GTB-5550 across multipl...