GT Biopharma, Inc. (NASDAQ: GTBP) announced that it has filed an Investigational New Drug (IND) application with the U.S. Food and Drug Administration for its B7‑H3‑targeted TriKE, GTB‑5550. The IND was submitted in December 2025 and the filing was disclosed on January 15 2026, marking the next step in the company’s plan to bring its second‑generation camelid nanobody TriKE platform into clinical testing for solid‑tumor cancers.
GTB‑5550 is a dual‑nanobody TriKE that engages CD16 on natural killer (NK) cells, delivers an IL‑15 expansion signal, and targets the B7‑H3 antigen expressed on a wide range of solid tumors. The company plans to initiate a Phase 1 basket trial in 2026, with subcutaneous dosing designed to improve patient convenience over traditional intravenous bispecifics. The trial will evaluate GTB‑5550 across multiple solid tumor types, including castration‑resistant prostate cancer, ovarian cancer, breast cancer, head and neck cancer, non‑small cell lung cancer, pancreatic cancer, and bladder cancer.
The IND filing is a key regulatory milestone that signals GT Biopharma’s readiness to move from preclinical development to human trials. Successful progression through the IND review will allow the company to evaluate safety, tolerability, and early efficacy signals in patients, potentially opening a large market for its platform and providing a critical data point for future partnership or acquisition discussions. Management emphasized that the IND submission “represents another NK cell engager we plan to move into clinical development and a tremendous accomplishment for the company.”
GT Biopharma’s preliminary, unaudited cash balance of approximately $7 million as of December 31 2025 is expected to fund operations into the third quarter of 2026, giving the company runway to support the Phase 1 program and ongoing development of its first‑generation TriKE, GTB‑3650. The company also noted that data readouts for GTB‑3650 are anticipated in the first half of 2026, which will inform the design and expectations for GTB‑5550.
The announcement was well received by investors, with the company’s stock rising 12.92% in the pre‑market session on January 15 2026. The positive market reaction reflects confidence in the company’s platform technology, the large addressable market for B7‑H3‑targeted therapies, and the de‑risking effect of an IND clearance.
The B7‑H3 antigen is expressed on a wide range of solid tumors and is considered a promising target for immunotherapy due to its limited expression on healthy tissues. GT Biopharma’s TriKE platform offers potential advantages over bispecific antibodies, cell therapies, and antibody‑drug conjugates, positioning the company in a competitive immuno‑oncology space where other firms are also developing NK cell engagers and B7‑H3‑targeted therapies. The IND filing therefore strengthens GT Biopharma’s competitive positioning and expands its pipeline beyond hematologic malignancies.
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