GT Biopharma Inc. (NASDAQ:GTBP) saw its stock rise 4.1% on Wednesday after announcing that its Phase 1 study for its lead immunotherapy, GTB 3650, has progressed to a higher dose tier.
GTB 3650 — a second-generation TriKE engineered to stimulate natural killer (NK) cells to attack cancer — has now been administered to six patients across the first three dosing cohorts without any tolerability concerns. With those safety milestones cleared, investigators have authorized enrollment into Cohort 4, where dosing will increase to 10 µg/kg/day, a level that management has described as “more reflective of the potential efficacy threshold.”
Across the early cohorts, researchers observed increased NK cell activity, reinforcing the immune-activation and expansion mechanism that forms the basis of the TriKE platform. The ongoing Phase 1 trial is focused on patients with relapsed or refractory acute myeloid leukemia (AML) and high-risk myelodysplastic syndrome (MDS).
At the same time, GT Biopharma is preparing its solid-tumor candidate GTB 5550 — a B7H3-targeting TriKE featuring a dual camelid nanobody structure and subcutaneous dosing — for an IND submission planned for late December 2025 or January 2026. The therapy is designed to offer a more convenient alternative to continuous infusion.
The company ended the third quarter of 2025 with $2.6 million in cash, which it expects will support operations into early 2026. GT Biopharma’s pipeline progress comes during a period of rapid expansion in oncology: the global cancer therapeutics market is projected to grow from $139.4 billion in 2025 to $268.3 billion by 2034, reflecting a 7.5% CAGR.