Core Insights - GT Biopharma, Inc. is a clinical stage immuno-oncology company focused on developing therapeutics based on its proprietary TriKE NK cell engager platform [1][3] - The company will participate in the Centurion One Capital 9th Annual Toronto Growth Conference on March 5, 2026, where one-on-one meetings with investors will be available [1][2] Company Overview - GT Biopharma is dedicated to the development and commercialization of immuno-oncology therapeutic products utilizing the TriKE platform, which enhances the cancer-killing abilities of natural killer cells in the immune system [3] - The company holds an exclusive worldwide license agreement with the University of Minnesota for the further development and commercialization of therapies using TriKE technology [3]

Core Insights - GT Biopharma has received FDA clearance for its IND application for GTB-5550, allowing the initiation of a Phase 1 clinical trial expected to start in mid-2026 [1][2] - The Phase 1 trial will focus on multiple solid tumor types expressing B7-H3, with a priority on advanced prostate, ovarian, and pancreatic cancer patients who have failed standard therapies [2][3] - The company anticipates an unaudited proforma cash balance of approximately $9 million as of January 31, 2026, which is expected to extend its cash runway through Q4 2026 [1] Company Overview - GT Biopharma is a clinical stage immuno-oncology company that develops therapeutics based on its proprietary TriKE NK cell engager platform [5] - The TriKE platform aims to enhance the cancer-killing abilities of natural killer cells in the immune system [5] - The company has an exclusive worldwide license agreement with the University of Minnesota for the development and commercialization of therapies using TriKE technology [5] Clinical Trial Details - The Phase 1 trial will include a dose escalation component testing up to 6 dose levels to identify the maximum tolerated dose (MTD) [3] - Following the dose escalation, a Phase 1b expansion will confirm the MTD in various metastatic disease cohorts, including castration-resistant prostate cancer and others [3] - GTB-5550 will be administered via subcutaneous injection for 5 consecutive days during the first two weeks of each 4-week treatment cycle, with patient follow-up for 12 months to assess progression-free survival and overall survival [4]

As filed with the Securities and Exchange Commission on January 21, 2026. Registration No. 333- UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 GT BIOPHARMA, INC. (Exact Name of Registrant as Specified in Its Charter) (State or Other Jurisdiction of Incorporation or Organization) Delaware 2834 94-1620407 (Primary Standard Industrial Classification Code Number) (I.R.S. Employer Identification Number) N/A (415) 919-4040 ( ...

Core Insights - GT Biopharma is targeting a segment of the estimated $362 billion global solid tumor market with its investigational drug GTB-5550, a B7-H3-targeted NK cell engager [1][2] - The company has submitted an IND application to the FDA for GTB-5550, which is expected to enter clinical trials in 2026 [1][2] - The company anticipates a cash balance of approximately $7 million as of December 31, 2025, which is expected to extend its cash runway into Q3 2026 [1] Company Overview - GT Biopharma is a clinical stage biopharmaceutical company focused on developing immuno-oncology therapeutics based on its proprietary TriKE NK cell engager platform [6] - The company has an exclusive worldwide license agreement with the University of Minnesota to further develop and commercialize therapies using TriKE technology [6] Product Development - GTB-5550 is a tri-specific NK cell engager designed to enhance the cancer-killing abilities of NK cells by targeting B7-H3 expressed on tumor cells [3] - The planned Phase 1 trial for GTB-5550 will be the first dual nanobody TriKE tested with subcutaneous dosing, aiming to identify the maximum tolerated dose (MTD) across various metastatic cancers [4] - The trial will include a dose escalation phase and a dose expansion phase, evaluating tolerability and efficacy in multiple solid tumor cohorts [4][5] Market Potential - The global market for B7-H3 expressing solid tumor cancers is a significant portion of the overall solid tumor market, indicating a large potential patient population for GTB-5550 [2]

Core Viewpoint - GT Biopharma Inc. has submitted an investigational new drug (IND) application for GTB-5550 TriKE, targeting B7-H3-expressing solid tumors, marking a significant step in its clinical development pipeline [1][2]. Company Developments - The IND for GTB-5550 is the third NK cell engager the company plans to advance into clinical trials, with a Phase 1 basket trial scheduled for 2026 [2]. - The company is currently enrolling patients in a Phase 1 trial for GTB-3650, focusing on myeloid blood cancer, with data readout expected in the first half of 2026 [3]. Market Context - The global market for B7-H3 expressing solid tumor cancers is part of the estimated $362 billion global solid tumor cancers market, indicating substantial commercial potential [3]. Trial Design - The Phase 1a trial will include a dose escalation study to determine the maximum tolerated dose (MTD) across 7 dose levels [4]. - The Phase 1b trial will confirm the MTD identified in Phase 1a and evaluate tolerability across distinct metastatic disease cohorts [4]. Treatment Protocol - GTB-5550 will be administered via subcutaneous injection for 5 consecutive days during the first two weeks, followed by a treatment-free period, with a minimum of 2 treatment cycles planned [5]. - Patients will be monitored for 12 months to assess progression-free survival (PFS) and overall survival (OS) [6]. Stock Performance - Following the announcement, GTBP stock experienced a 12.92% increase, reaching $0.75 in premarket trading [6].

Core Viewpoint - The article serves as a paid advertisement for GT Biopharma, Inc., highlighting its potential investment opportunities while disclosing conflicts of interest related to the promotion of the company [1] Group 1: Company Overview - GT Biopharma, Inc. is being promoted as a company with promising prospects in the biopharmaceutical sector, particularly in the development of innovative therapies [1] - The article emphasizes the company's ongoing digital media efforts to increase visibility and attract investor interest [1] Group 2: Financial Considerations - The article notes that the owner/operator of the advertising entity does not currently own shares of GT Biopharma, Inc. but reserves the right to buy and sell shares at any time [1] - It is mentioned that there may be third parties holding shares of GT Biopharma, Inc. who could liquidate their holdings, potentially impacting the stock price negatively [1]

Core Insights - The FDA's recent approval of the first bispecific antibody combination for second-line blood cancer treatment signifies a major shift from traditional chemotherapy, with engineered cell therapies and bispecific antibodies achieving response rates over 90% in relapsed and refractory hematologic malignancies [1][2] Company Developments - GT Biopharma, Inc. is advancing its Phase 1 clinical trial of GTB-3650 to Cohort 4, with patients receiving a dose of 10 µg/kg/day, focusing on relapsed or refractory blood cancers expressing CD33, particularly acute myeloid leukemia (AML) and high-risk myelodysplastic syndrome (MDS) [3][4][6] - The therapy utilizes the patient's natural killer cells to target cancer cells, with treatment structured in two-week cycles followed by rest intervals, continuing for up to four months based on patient response [5][6] - The current dose in Cohort 4 is seen as a threshold for potential clinical efficacy, supported by positive immunological biomarker trends and no dose-limiting toxicities reported across previous cohorts [6][7] - GT Biopharma is also developing GTB-5550, targeting B7H3 in various solid tumors, with regulatory submission for human trials expected in late December 2025 or January 2026 [8][9] Market Trends - The CAR-T cell therapy market is projected to grow from $3.87 billion in 2024 to $13.25 billion by 2030, driven by its efficacy in treating relapsed and refractory patient populations [2]

Core Insights - Patients with aggressive blood cancers have limited treatment options and uncertain outcomes [1] - There is a growing focus among scientists on utilizing the body's own defenses, specifically developing therapies that enhance natural killer (NK) cells to target and eliminate malignant cells [1] Industry Trends - The development of NK cell therapies represents a significant advancement in the treatment landscape for aggressive blood cancers [1] - This approach highlights a shift towards immunotherapy, leveraging the immune system to combat cancer more effectively [1]

Clinical Development - GTB-3550 showed interim clinical trial results with reduced CD33+ bone marrow blast levels by 33.3%, 61.7%, 63.6%, and 50% across different patient doses[131]. - GTB-3650, a next-generation TriKE®, is anticipated to enhance efficacy in treating relapsed/refractory AML and high-risk MDS, with an IND application filed in December 2023 and cleared by the FDA in June 2024[140]. - GTB-5550 targets B7-H3 on advanced solid tumors, with preclinical studies demonstrating NK-cell targeted activity against various cancers, and an IND application expected by late December 2025 or January 2026[142]. - GTB-7550 is in development for lupus and other autoimmune disorders, effectively targeting CD19+ malignant cell lines and primary CLL[143][144]. - The TriKE® platforms are designed to activate NK cells, potentially offering a safer alternative to T-cell immunotherapy with reduced cytokine release syndrome[125][126]. - The company is focusing on developing second-generation TriKEs utilizing camelid nanobody technology, which may provide greater affinity and potency against target antigens[133][135]. - The IND application for GTB-3650 was filed with the FDA in December 2023, with study enrollment for patients starting on January 21, 2025[140]. - The company has exclusive rights to the TriKE® platform and is generating additional intellectual property for specific moieties[127]. Financial Performance - Research and development expenses decreased by approximately $0.7 million (51%) for the three months and $1.8 million (46%) for the nine months ended September 30, 2025, primarily due to a decrease in production and material costs[152][161]. - Total operating expenses for the three months ended September 30, 2025, were $3.38 million, a decrease of $222,000 (6%) compared to the same period in 2024; for the nine months, total operating expenses were $6.83 million, down $3.77 million (36%) year-over-year[151]. - Net loss for the three months ended September 30, 2025, was $3.11 million, a decrease of $297,000 (9%); for the nine months, net loss was $5.32 million, down $4.06 million (43%) compared to the prior year[161]. - Cash used in operating activities was approximately $8.89 million for the nine months ended September 30, 2025, compared to $10.44 million for the same period in 2024[165][166]. - Current assets increased by $89,000 to $4.32 million as of September 30, 2025, while current liabilities decreased by $4.58 million to $1.32 million, resulting in a working capital improvement of $4.67 million[169]. - Interest income decreased by $60,000 (63%) for the three months and $237,000 (69%) for the nine months ended September 30, 2025, due to lower money market fund and short-term investment balances[156]. - The change in fair value of warrant liability increased by $137,000 (144%) for the three months but decreased by $626,000 (72%) for the nine months ended September 30, 2025, primarily due to stock price fluctuations[157][158]. - The company recorded a gain of $998,000 on the settlement of vendor payable in March 2025, which was classified as other income[159]. - Net cash provided by financing activities was approximately $7.47 million for the nine months ended September 30, 2025, compared to $2.98 million for the same period in 2024[168]. - The company has raised substantial doubt about its ability to continue as a going concern, with a net loss of approximately $5.3 million and cash used in operations of approximately $8.9 million for the nine months ended September 30, 2025[162][164]. Accounting and Financial Reporting - The financial statements preparation involves significant estimates, including accruals for potential liabilities and fair value of warrant liabilities[145][146]. - Stock-based compensation is periodically issued, with expenses recognized based on grant date fair values, affecting future periods' compensation expense[150].

Financial Results - GT Biopharma, Inc. announced its financial results for the fiscal quarter ended September 30, 2025[4]. - The press release detailing the financial results was issued on November 14, 2025[4]. - The financial results include key metrics that will be detailed in Exhibit 99.1[4]. - The financial statements and exhibits are included in the filing[6]. Company Structure - The company became a fully remote organization effective July 1, 2024, and no longer maintains a principal executive office[3]. - The company has not indicated whether it is an emerging growth company[3]. Regulatory Information - The report is not deemed "filed" under the Securities Exchange Act of 1934[5]. - The report was signed by Alan Urban, Chief Financial Officer[11]. Company Identification - The company is listed on The Nasdaq Stock Market under the trading symbol GTBP[2]. - The company’s IRS Employer Identification Number is 94-1620407[1].