GT Biopharma, Inc. (GTBP) announced that the first patient has been dosed in its Phase 1 basket trial evaluating GTB-5550, a B7-H3-targeted natural killer (NK) cell engager for solid tumors. The milestone marks the third TriKE candidate to enter clinical testing and expands the company's platform into a broader solid tumor opportunity.
The Phase 1a dose escalation portion of the study will primarily enroll patients with metastatic castration-resistant prostate cancer, a disease in which B7-H3 is expressed in more than 90 percent of tumors. Up to six dose levels will be tested to determine the maximum tolerated dose. Following this, the Phase 1b expansion will include patients with as many as seven different tumor types, including ovarian, breast, head and neck, non-small cell lung, pancreatic, and bladder cancers.
GTB-5550 is the first nanobody TriKE to be tested with subcutaneous dosing, designed to be more patient-friendly. Treatment cycles involve injections during the first two weeks, followed by two weeks off, with reassessment planned after two cycles and every 8-12 weeks thereafter. Patients will be followed for 12 months to evaluate progression free survival (PFS) and overall survival (OS).
Michael Breen, Executive Chairman and CEO of GT Biopharma, described the first dosing as a pivotal milestone, noting that the company's ongoing progress with GTB-3650 in blood cancers has provided confidence to advance GTB-5550 into solid tumors. Updates on trial progress are expected in the second half of 2026.
GT Biopharma's TriKe platform is designed to harness and enhance the cancer killing abilities of a patient's immune system's natural killer cells. The company holds an exclusive worldwide license agreement with the University of Minnesota to further develop and commercialize therapies using TriKE technology.
GTBP has traded between $0.26 and $3.85 over the past year. The stock is currently trading at $0.42, up 35.91%.
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