GT Biopharma Oral Presentation at the SITC 2026 Annual Meeting

GT Biopharma showcased new preclinical data in an oral presentation at SITC demonstrating an enhanced effect of combining GTB-5550, a B7-H3-targeted tri-specific NK cell engager (TriKE^®), with a KRAS inhibitor (KRASi), which was shown to sensitize pancreatic tumor cells to NK cell cytotoxicity

The new data show that the combination promotes NK cell infiltration to provide superior disease control in orthotopic xenograft models, and provides novel mechanistic insight into KRAS-dependent anti-tumor NK regulation to establish a strong preclinical rationale for combining KRASi with GTB-5550 in pancreatic ductal adenocarcinoma (PDAC)

A Phase 1a/1b basket trial with GTB-5550 monotherapy is currently underway (NCT07541573), which includes a cohort for PDAC patients, and the Company is considering potential options for a future Phase 1b study to evaluate the combination of GTB-5550 and a KRAS inhibitor

SAN FRANCISCO, CALIFORNIA, Nov. 09, 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 preclinical data presented at the Society for Immunotherapy of Cancer (SITC) 2026 Annual Meeting taking place from November 4-8, 2026 in Phoenix, AZ.

“We continue to make progress enrolling patients into our ongoing Phase 1a/1b dose escalation basket trial with GTB-5550 in multiple tumor types”, said Michael Breen, Executive Chairman and Chief Executive Officer of GT Biopharma. “Given the recent advances in this field with KRAS inhibitors becoming a new standard of care and these extremely compelling preclinical results, we are considering all options to conduct a future Phase 1b study combining GTB-5550 with a KRASi in pancreatic cancer patients”.

Despite significant recent advances in the field, monotherapy with RAS inhibitors can trigger early resistance via bypass pathways, and the industry is moving more towards the opportunity for multi-drug combinations to provide deeper, more durable responses than single agent KRAS inhibition. The new data demonstrate that GTB-5550 has the potential to improve the effectiveness of KRAS inhibition by making pancreatic cancer cells more susceptible to NK cell cytotoxicity. In orthotopic PDAC xenograft models, the combination of GTB-5550 plus KRASi demonstrated superior tumor control, including complete tumor clearance in several animals, while significantly reducing local invasion and preventing metastasis. When compared to KRASi treatment alone, KRASi + GTB-5550 treatment was associated with a two-fold increase in tumor-infiltration, as well as increases in persistence and CXCR3 expression of adoptively transferred NK cells. This enhanced treatment effect also correlated with a corresponding increase in apoptosis markers on tumor cells.

Oral Presentation Details

Title: Inhibition of the KRAS oncoprotein sensitizes pancreatic cancer to NK cell immunotherapy
Abstract No.: 655
Presenter: Paarth Dodhiawala, University of Minnesota Medical School¹
Date: Friday, November 6, 2026
Time: 3:05-3:20 PM MT
Session 106a: Combination Therapies Involving Cell Therapy, 1:45-3:25 PM MST
Session Description: While cell therapy has transformed the treatment of certain hematologic malignancies, its impact in solid tumors remains limited by antigen heterogeneity, immunosuppressive microenvironments, and nutrient deprivation. As efforts to engineer more effective immune cells continue, there is growing interest in combining cell therapies with complementary approaches to enhance their function and engage endogenous immunity. This session will highlight diverse strategies to extend the clinical impact of cell therapies through rational combination approaches.

About GT Biopharma, Inc.

GT Biopharma, Inc. is a clinical stage biopharmaceutical company focused on the development and commercialization of immuno-oncology therapeutic products based on our proprietary TriKE^® NK cell engager platform. Our TriKE^® platform is designed to harness and enhance the cancer killing abilities of a patient’s immune system’s natural killer cells. GT Biopharma has an exclusive worldwide license agreement with the University of Minnesota to further develop and commercialize therapies using TriKE^® technology. For more information, please visit gtbiopharma.com.

Forward-Looking Statements

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TriKE^® is a registered trademark owned by GT Biopharma, Inc.

Investor Relations Contact:

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¹ The University of Minnesota, pursuant to its license agreement with GT Biopharma, is entitled to receive royalties should commercial sales of product using the TriKE^® technology be realized, including GTB-3650 and GTB-5550. This interest has been reviewed and managed by the University of Minnesota in accordance with its conflict of interest policies.