GTBP

Phase 1 trial evaluating GTB-3650 TriKE® remains ongoing, with an update anticipated in 2H 2026 Phase 1 basket trial evaluating GTB-5550 TriKE® in multiple solid tumor types known to express B7-H3 initiated May 2026 with an update anticipated in 2H 2026 as enrollment progresses through dose escalation cohorts Increased integration of artificial intelligence–based tools across the discovery and engineering of tumor-targeting engagers and multi-domain proteins, supporting the anticipation of multiple new development candidates moving towards pre-IND development in 2027 Cash balance as of June 30, 2026 of approximately $5.1 million anticipated to provide sufficient cash runway through Q4 2026 SAN FRANCISCO, CALIFORNIA, Aug. 14, 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 natural killer (NK) cell engager TriKE® platform, today announced second quarter 2026 financial results for the period ended June 30, 2026. "We now have two TriKE® candidates actively enrolling patients and look forward to additional updates later this year," said Michael Breen, Executive Chairman and Chief Executive Officer. "Utilizing our deep platform expertise, our discovery efforts continue to be extremely productive, and we anticipate announcing IND clearance for an additional TriKE® pipeline asset in 2026. With sufficient cash runway through Q4 2026, we look forward to providing updates on all programs in the second half of 2026." GTB-3650 TriKE for CD33 positive leukemias The ongoing Phase 1 dose escalation study is evaluating GTB-3650 for relapsed or refractory (r/r) CD33 expressing hematologic malignancies, including refractory acute myeloid leukemia and high-risk myelodysplastic syndrome. Enrollment is ongoing, with Cohort 4 complete and enrollment of Cohort 5 in progress. The Company expects to provide an update in the 2H 2026. Dose escalation may continue up to Cohort 7 as necessary with the potential to evaluate GTB-3650 in a total of 14 patients (two patients per cohort). GTB-3650 is dosed in two-week blocks, two weeks on and two weeks off, for up to four months based on clinical benefit. The trial aims to assess the safety, pharmacokinetics, pharmacodynamics, in vivo expansion of endogenous patient NK cells and clinical activity. GTB-5550 TriKE for B7H3 positive solid tumor cancers The ongoing Phase 1 trial with GTB-5550 is the first nanobody TriKE® tested with more patient-friendly subcutaneous dosing. The Phase 1a dose escalation portion of the trial is focused primarily on enrolling prostate cancer patients and will evaluate up to 6 dose levels to identify the maximum tolerated dose (MTD). Enrollment in Cohort 1 is complete and enrollment in Cohort 2 is in progress. The Company expects to provide an update in the 2H 2026. After the dose escalation phase, the Phase 1b expansion component will enroll patients with up to 7 different tumor types (castration-resistant prostate cancer, ovarian cancer, breast cancer, head and neck cancer, non-small cell lung cancer, pancreatic cancer, and bladder cancer) and further evaluate its safety, tolerability and preliminary anti-tumor activity. GTB-5550 will be administered by subcutaneous (SQ) injection in the abdominal area for 5 consecutive days during Week 1 and Week 2 followed by 2 weeks of no treatment. One treatment cycle is 4 weeks in duration. Subsequent cycles receive treatment three times weekly for 2 weeks followed by 2 weeks of no treatment. A minimum of 2 cycles is planned, and patient-appropriate disease reassessment is performed after 2 cycles and every 8-12 weeks thereafter. Treatment may continue until disease progression, unacceptable toxicity, patient refusal, or treatment is no longer in the best interest of the patient. Patients are followed for 12 months to determine progression free survival (PFS) and overall survival (OS). More details can be found on clinicaltrials.gov with the identifier: NCT07541573. Second Quarter Ended June 30, 2026 Financial Summary Cash Position: The Company had cash and cash equivalents of approximately $5.1 million as of June 30, 2026, which is anticipated to be sufficient to fund the Company’s operations through the fourth quarter of 2026. Research and Development (R&D) Expenses: R&D expenses for the second quarter of 2026 were approximately $1.1 million compared to $0.4 million for the same comparable quarter of 2025. The $0.7 million increase was primarily due to an increase in materials and production costs. R&D expenses primarily relate to the Company’s continued licensing, development, production, and clinical trials of its most advanced TriKE® product candidates GTB-3650 and GTB-5550 along with the progression on other promising product candidates. In late June 2024, the Company received clearance from the Food and Drug Administration with respect to its IND application in relation to its next generation GTB-3650 camelid nanobody product. Study enrollment began in early 2025 and the Company has advanced into the clinic with the first four cohorts now enrolled. In January 2026, the Company received clearance from the FDA on its IND Application for GTB-5550. The first patient in a Phase 1 dose escalation basket trial was dosed in May 2026. Selling, General and Administrative (SG&A) Expenses: SG&A expenses for the second quarter of 2026 were approximately $3.4 million compared to $1.1 million for the same comparable quarter of 2025. The $2.3 million increase was primarily due to an increase in marketing expenses, and to a lesser extent, legal and consulting fees. Loss from Operations: The Company reported a loss from operations for the second quarter of 2026 of approximately $4.5 million compared to $1.5 million for the same comparable quarter of 2025. The $3 million increase was primarily due to a $2.3 million increase in SG&A expenses, and a $0.7 million increase in R&D expenses, as described above. Net Loss: The Company reported a net loss for the second quarter of 2026 of approximately $4.5 million, compared to $30.2 million for the same comparable quarter of 2025. The $25.7 million decrease consisted primarily of the initial recognition of Greenshoe Rights liability of $28.7 million (non-cash and non-recurring) which occurred in the same comparable quarter of 2025 and did not occur in the current quarter, slightly offset by an increase in R&D and SG&A expenses, as described above. 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 Certain statements in this press release may constitute "forward-looking statements" regarding future events and our future results. All statements other than statements of historical facts are statements that could be deemed to be forward- looking statements. These statements are based on current expectations, estimates, forecasts, and projections about the markets in which we operate and the beliefs and assumptions of our management. Words such as “aims,” "expects," "anticipates," "targets," "goals," "projects", "intends," "plans," "believes," "seeks," "estimates," "endeavors," "strives," "may," or variations of such words, and similar expressions are intended to identify such forward-looking statements. Readers are cautioned that the use of these forward-looking statements are subject to a number of risks, uncertainties and assumptions that are difficult to predict, estimate or verify. Therefore, actual results may differ materially and adversely from those expressed in any forward-looking statements. Such risks and uncertainties include (i) the Company’s ability to continue as a going concern; (ii) the risk that if the Company experiences delays or difficulties in the enrollment of patients in clinical trials, those clinical trials could take longer than expected to complete and the Company’s receipt of necessary regulatory approvals could be delayed or prevented; (iii) the risk that the Company will need additional capital to conduct its operations and develop its products, and the Company’s ability to obtain the necessary funding is uncertain; (iv) the risk that the Company’s common stock may be delisted in the future if the Company is unable to maintain compliance with continued listing requirements; (v) the risk that the Company’s products may fail to achieve necessary safety and efficacy endpoints during clinical trials, which may limit the company’s ability to generate revenues from therapeutic products and (vi) those other factors described in our most recent annual report on Form 10-K, as such may be amended or supplemented by subsequent quarterly reports on Form 10-Q, or other reports filed with the Securities and Exchange Commission. Readers are cautioned not to place undue reliance on these forward-looking statements. The forward-looking statements are made only as of the date hereof, and we undertake no obligation to publicly release the result of any revisions to these forward-looking statements. For more information, please refer to our filings with the Securities and Exchange Commission. TriKE® is a registered trademark owned by GT Biopharma, Inc. Investor Relations Contact: LifeSci AdvisorsCorey Davis, [email protected] LinkedIn |Facebook |X |Instagram | YouTube

Phase 1 trial evaluating GTB-3650 TriKE® remains ongoing, with additional updates anticipated in 2H 2026 Phase 1 basket trial evaluating GTB-5550 TriKE® in multiple solid tumor types known to express B7-H3 initiated May 2026 with updates anticipated in 2H 2026 as enrollment progresses through dose escalation cohorts Cash balance as of March 31, 2026 of approximately $9 million anticipated to provide sufficient cash runway through Q4 2026 SAN FRANCISCO, CALIFORNIA, May 15, 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 natural killer (NK) cell engager TriKE® platform, today announced first quarter 2026 financial results for the period ended March 31, 2026. "With the initiation of our GTB-5550 Phase 1 trial, we have now advanced three TriKE® candidates into the clinic, a significant milestone that underscores the continued momentum of our pipeline," said Michael Breen, Executive Chairman and Chief Executive Officer. "GTB-3650 has demonstrated an excellent safety profile thus far, and we look forward to continuing enrollment progress. With sufficient cash runway through Q4 2026, we look forward to providing updates on both programs in the second half of 2026." GTB-3650 TriKE for CD33 positive leukemias The ongoing Phase 1 dose escalation study is evaluating GTB-3650 for relapsed or refractory (r/r) CD33 expressing hematologic malignancies, including refractory acute myeloid leukemia and high-risk myelodysplastic syndrome. Enrollment is ongoing, with Cohort 4 enrollment now complete and a total of 8 patients treated across the first four cohorts; the Company expects to provide continued progress updates throughout 2026. Dose escalation may continue up to Cohort 7 as necessary with the potential to evaluate GTB-3650 in a total of 14 patients (two patients per cohort). GTB-3650 is dosed in two-week blocks, two weeks on and two weeks off, for up to four months based on clinical benefit. The trial aims to assess the safety, pharmacokinetics, pharmacodynamics, in vivo expansion of endogenous patient NK cells and clinical activity. GTB-5550 TriKE for B7H3 positive solid tumor cancers The ongoing Phase 1 trial with GTB-5550 is the first nanobody TriKE® tested with more patient-friendly subcutaneous dosing. The Phase 1a dose escalation portion of the trial is focused primarily on enrolling prostate cancer patients and will evaluate up to 6 dose levels to identify the maximum tolerated dose (MTD). After the dose escalation phase, the Phase 1b expansion component will enroll patients with up to 7 different tumor types (castration-resistant prostate cancer, ovarian cancer, breast cancer, head and neck cancer, non-small cell lung cancer, pancreatic cancer, and bladder cancer) and further evaluate its safety, tolerability and preliminary anti-tumor activity. GTB-5550 will be administered by subcutaneous (SQ) injection in the abdominal area for 5 consecutive days during Week 1 and Week 2 followed by 2 weeks of no treatment. One treatment cycle is 4 weeks in duration. Subsequent cycles receive treatment three times weekly for 2 weeks followed by 2 weeks of no treatment. A minimum of 2 cycles is planned, and patient-appropriate disease reassessment is performed after 2 cycles and every 8-12 weeks thereafter. Treatment may continue until disease progression, unacceptable toxicity, patient refusal, or treatment is no longer in the best interest of the patient. Patients are followed for 12 months to determine progression free survival (PFS) and overall survival (OS). More details can be found on clinicaltrials.gov with the identifier: NCT07541573. First Quarter Ended March 31, 2026 Financial Summary Cash Position: The Company had cash and cash equivalents of approximately $9 million as of March 31, 2026, which is anticipated to be sufficient to fund the Company’s operations through the fourth quarter of 2026. Research and Development (R&D) Expenses: R&D expenses for the second quarter of 2026 were approximately $400,000 compared to $1.1 million for the same comparable quarter of 2025. The $700,000 decrease was primarily due to a reduction in production costs. R&D expenses primarily relate to the Company’s continued licensing, development, production, and clinical trials of its most advanced TriKE® product candidates GTB-3650 and GTB-5550 along with the progression on other promising product candidates. Selling, General and Administrative (SG&A) Expenses (Excluding Stock Compensation): SG&A expenses for the second quarter of 2026 were approximately $2.4 million compared to $800,000 for the same comparable quarter of 2025. The $1.6 million increase was primarily due to an increase in marketing expenses, and to a lesser extent, legal fees. Loss from Operations: The Company reported a loss from operations for the second quarter of 2026 of approximately $2.8 million compared to $1.9 million for the same comparable quarter of 2025. The 900,000 increase was primarily due to $1.6 million increase in SG&A (as described above). Net Loss: The Company reported a net loss of approximately $2.8 million for the second quarter of 2026, compared to $800,000 for same comparable quarter of 2025. The $2 million increase consisted primarily of a $1.6 million increase in SG&A (as described above), and a decrease in non-recurring other income of approximately $1.1 million. 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 Certain statements in this press release may constitute "forward-looking statements" regarding future events and our future results. All statements other than statements of historical facts are statements that could be deemed to be forward- looking statements. These statements are based on current expectations, estimates, forecasts, and projections about the markets in which we operate and the beliefs and assumptions of our management. Words such as “aims,” "expects," "anticipates," "targets," "goals," "projects", "intends," "plans," "believes," "seeks," "estimates," "endeavors," "strives," "may," or variations of such words, and similar expressions are intended to identify such forward-looking statements. Readers are cautioned that the use of these forward-looking statements are subject to a number of risks, uncertainties and assumptions that are difficult to predict, estimate or verify. Therefore, actual results may differ materially and adversely from those expressed in any forward-looking statements. Such risks and uncertainties include (i) the Company’s ability to continue as a going concern; (ii) the risk that if the Company experiences delays or difficulties in the enrollment of patients in clinical trials, those clinical trials could take longer than expected to complete and the Company’s receipt of necessary regulatory approvals could be delayed or prevented; (iii) the risk that the Company will need additional capital to conduct its operations and develop its products, and the Company’s ability to obtain the necessary funding is uncertain; (iv) the risk that the Company’s common stock may be delisted in the future if the Company is unable to maintain compliance with continued listing requirements; (v) the risk that the Company’s products may fail to achieve necessary safety and efficacy endpoints during clinical trials, which may limit the company’s ability to general revenues from therapeutic products and (vi) those other factors described in our most recent annual report on Form 10-K, as such may be amended or supplemented by subsequent quarterly reports on Form 10-Q, or other reports filed with the Securities and Exchange Commission. Readers are cautioned not to place undue reliance on these forward-looking statements. The forward-looking statements are made only as of the date hereof, and we undertake no obligation to publicly release the result of any revisions to these forward-looking statements. For more information, please refer to our filings with the Securities and Exchange Commission. TriKE® is a registered trademark owned by GT Biopharma, Inc. Investor Relations Contact: LifeSci Advisors Corey Davis, Ph.D. [email protected] 212-915-2577 LinkedIn |Facebook |X |Instagram | YouTube

Phase 1 trial evaluating GTB-3650 TriKE® continues to actively enroll, with the next update anticipated in Q3 2026 following completion of enrollment in dose Cohort 5 Phase 1 basket trial evaluating GTB-5550 TriKE® in multiple solid tumor types known to express B7-H3 remains on track to initiate mid-2026 Unaudited proforma cash balance as of January 31, 2026 of approximately $9 million anticipated to provide sufficient cash runway through Q4 2026 SAN FRANCISCO, CALIFORNIA, March 02, 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 natural killer (NK) cell engager TriKE® platform, today announced full year 2025 financial results for the period ended December 31, 2025. “2026 looks to bring more significant milestones for the company, as we plan to initiate the first clinical trial with GTB-5550,” said Michael Breen, Executive Chairman and Chief Executive Officer. “Advancing our third TriKE candidate into the clinic underscores the continued momentum of our pipeline. GTB-3650 has shown an excellent safety profile thus far, and the higher dose cohorts will be more reflective of surpassing a potential efficacy threshold. With sufficient cash runway through Q4 2026, we look forward to providing the next update in the third quarter of 2026.” GTB-3650 TriKE for CD33 positive leukemias The ongoing Phase 1 dose escalation study is evaluating GTB-3650 for relapsed or refractory (r/r) CD33 expressing hematologic malignancies, including refractory acute myeloid leukemia and high-risk myelodysplastic syndrome. Enrollment in Cohort 4 (10 µg/kg/day) is ongoing, and the Company expects to initiate dosing in Cohort 5 (25 µg/kg/day) in Q2 2026. The Company anticipates providing the next update in the third quarter of 2026, which would include longer term follow-up on the six patients in Cohort 1 through 3 as well as initial observations from patients in Cohort 4 and Cohort 5. Dose escalation may continue up to Cohort 7 as necessary with the potential to evaluate GTB-3650 in a total of 14 patients (two patients per cohort). GTB-3650 is dosed in two-week blocks, two weeks on and two weeks off, for up to four months based on clinical benefit. The trial aims to assess the safety, pharmacokinetics, pharmacodynamics, in vivo expansion of endogenous patient NK cells and clinical activity. GTB-5550 TriKE for B7H3 positive solid tumor cancers The Phase 1 basket trial with GTB-5550 will be the first dual nanobody TriKE® tested with more patient-friendly subcutaneous dosing. The Phase 1a dose escalation portion of the trial will test up to 6 dose levels to identify the maximum tolerated dose (MTD). After the dose escalation phase, the Phase 2 expansion component of the trial will then confirm the MTD identified in the Phase 1a trial in up to seven different possible metastatic disease cohorts (castration-resistant prostate cancer, ovarian cancer, breast cancer, head and neck cancer, non-small cell lung cancer, pancreatic cancer, and bladder cancer) and further evaluate its safety, tolerability and preliminary anti-tumor activity. The Company remains well on track to initiate the trial in mid-2026. GTB-5550 will be administered by subcutaneous (SQ) injection in the abdominal area for 5 consecutive days during Week 1 and Week 2 followed by 2 weeks of no treatment. One treatment cycle is 4 weeks in duration. A minimum of 2 cycles is planned, and patient-appropriate disease reassessment is performed after 2 cycles and every 8-12 weeks thereafter. Treatment may continue until disease progression, unacceptable toxicity, patient refusal, or treatment is no longer in the best interest of the patient. Patients are followed for 12 months to determine progression free survival (PFS) and overall survival (OS). Year Ended December 31, 2025 Financial Summary Cash Position: The Company had cash and cash equivalents of approximately $7 million as of December 31, 2025, and an unaudited proforma cash balance as of January 31, 2026 of approximately $9 million, which is anticipated to be sufficient to fund the Company’s operations through the fourth quarter of 2026. Research and Development (R&D) Expenses: R&D expenses for the year ended December 31, 2025 were approximately $3.5 million compared to $5.8 million for the prior year. The $2.3 million decrease was primarily due to a reduction in production and material costs. R&D expenses primarily relate to the Company’s continued licensing, development and production of its most advanced TriKE® product candidates GTB-3650 and GTB-5550 along with the progression on other promising product candidates. In late June 2024, the Company received clearance from the Food and Drug Administration with respect to its Investigational New Drug (“IND”) application in relation to its next generation GTB-3650 camelid nanobody product. Study enrollment began in early 2025 and the Company has advanced into the clinic, enrolling patients, and performing tests for data collection throughout the year. In late January 2026, the Company received clearance from the FDA with respect to its IND Application in relation to GTB-5550, with a Phase 1 dose escalation basket trial expected to initiate mid-2026. Selling, General and Administrative (SG&A) Expenses (Excluding Stock Compensation): SG&A expenses for the year ended December 31, 2025 were relatively flat compared to the prior year, amounting to approximately $8.5 million compared to $8.3 million, respectively. Loss from Operations: The Company reported a loss from operations of approximately $12.4 million for the year ended December 31, 2025, compared to $14.4 million for the prior year. The $2 million decrease consisted primarily of significant decreases in R&D expenses (as described above). Net Loss: The Company reported a net loss of approximately $28.4 million for the year ended December 31, 2025, compared to $13.2 million for the prior year. The $15.2 million increase consisted almost entirely of a non-cash expense resulting from the change in fair value of additional investment rights connected to the Company’s Series L Preferred Stock during the year. 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 Certain statements in this press release may constitute "forward-looking statements" regarding future events and our future results. All statements other than statements of historical facts are statements that could be deemed to be forward- looking statements. These statements are based on current expectations, estimates, forecasts, and projections about the markets in which we operate and the beliefs and assumptions of our management. Words such as “aims,” "expects," "anticipates," "targets," "goals," "projects", "intends," "plans," "believes," "seeks," "estimates," "endeavors," "strives," "may," or variations of such words, and similar expressions are intended to identify such forward-looking statements. Readers are cautioned that the use of these forward-looking statements are subject to a number of risks, uncertainties and assumptions that are difficult to predict, estimate or verify. Therefore, actual results may differ materially and adversely from those expressed in any forward-looking statements. Such risks and uncertainties include (i) the Company’s ability to continue as a going concern; (ii) the risk that if the Company experiences delays or difficulties in the enrollment of patients in clinical trials, those clinical trials could take longer than expected to complete and the Company’s receipt of necessary regulatory approvals could be delayed or prevented; (iii) the risk that the Company will need additional capital to conduct its operations and develop its products, and the Company’s ability to obtain the necessary funding is uncertain; (iv) the risk that the Company’s common stock may be delisted in the future if the Company is unable to maintain compliance with continued listing requirements; (v) the risk that the Company’s products may fail to achieve necessary safety and efficacy endpoints during clinical trials, which may limit the company’s ability to general revenues from therapeutic products and (vi) those other factors described in our most recent annual report on Form 10-K, as such may be amended or supplemented by subsequent quarterly reports on Form 10-Q, or other reports filed with the Securities and Exchange Commission. Readers are cautioned not to place undue reliance on these forward-looking statements. The forward-looking statements are made only as of the date hereof, and we undertake no obligation to publicly release the result of any revisions to these forward-looking statements. For more information, please refer to our filings with the Securities and Exchange Commission. TriKE® is a registered trademark owned by GT Biopharma, Inc. Investor Relations Contact: LifeSci Advisors Corey Davis, Ph.D. [email protected] 212-915-2577 LinkedIn |Facebook |X |Instagram | YouTube

Phase 1 trial evaluating GTB-3650 TriKE® for relapsed or refractory (r/r) CD33 expressing hematologic malignancies continues to actively enroll with the next update anticipated in Q1 2026 GTB-5550 TriKE® IND submission for B7H3-expressing solid tumors expected in late December 2025 or January 2026 SAN FRANCISCO, CALIFORNIA, Nov. 14, 2025 (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 natural killer (NK) cell engager TriKE® platform, today announced third quarter 2025 financial results for the period ended September 30, 2025. The Company’s Phase 1 dose escalation study is evaluating GTB-3650 in a total of 14 patients (two patients per cohort) with relapsed or refractory (r/r) CD33 expressing hematologic malignancies, including refractory acute myeloid leukemia and high-risk myelodysplastic syndrome. GTB-3650 is dosed in two-week blocks, two weeks on and two weeks off, for up to four months based on clinical benefit. The trial aims to assess the safety, pharmacokinetics, pharmacodynamics, in vivo expansion of endogenous patient NK cells and clinical activity. The Company plans to provide the next update on the trial in the first quarter of 2026 following completion of additional dose cohorts. “We are highly encouraged by the continued progress of our Phase 1 clinical trial evaluating GTB-3650 in cancer patients, which has now advanced to Cohort 4 at a dose level of 10 µg/kg/day,” said Michael Breen, Executive Chairman and Chief Executive Officer. “We look forward to assessing higher doses, as we are now approaching the efficacy range predicted by preclinical in vivo leukemia models, and we plan to share the next trial update in the first quarter of 2026. The excellent safety profile observed with GTB-3650 and the immune activation potential of bringing IL-15 to the immune synapse suggests a potential competitive advantage for GTB-5550 compared to other modalities like bispecific antibodies, cell therapies, and antibody drug conjugates also targeting solid tumors expressing B7H3, which is quicky emerging as a compelling novel immune checkpoint target.” Third Quarter 2025 Financial Summary Cash Position: The Company had cash and cash equivalents of approximately $2.6 million as of September 30, 2025, which is anticipated to be sufficient to fund the Company’s operations into the first quarter of 2026. Research and Development (R&D) Expenses: R&D expenses for the third quarter ended September 30, 2025 were approximately $0.6 million compared to $1.3 million for the same comparable quarter of 2024. The $0.7 million decrease was primarily due to a reduction in production and material costs. R&D expenses primarily relate to the Company’s continued licensing, development and production of its most advanced TriKE® product candidates GTB-3650 and GTB-5550 along with the progression on other promising product candidates. In late June 2024, the Company received clearance from the Food and Drug Administration with respect to the Company’s Investigational New Drug (“IND”) application in relation to the Company’s next generation GTB-3650 camelid nanobody product. Study enrollment began in early 2025 and the Company has advanced into the clinic, enrolling patients, and performing tests for data collection throughout the year. Following the financing completed in May 2025, the Company has restarted the final phase of product development of GTB-5550 and anticipates submission of an IND application for GTB-5550 in late December 2025 or in January 2026. Selling, General and Administrative (SG&A) Expenses (Excluding Stock Compensation): SG&A expenses for the third quarter ended September 30, 2025 were relatively flat compared to the same comparable quarter of 2024, amounting to approximately $2.4 million compared to $2.3 million, respectively. Net Loss: The Company reported a net loss of approximately $3.1 million for the third quarter ended September 30, 2025 compared to a net loss of $3.4 million for the same comparable quarter in 2024. The $0.3 million decrease consisted primarily of significant decreases in R&D expenses (as described above). 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 Certain statements in this press release may constitute "forward-looking statements" regarding future events and our future results. All statements other than statements of historical facts are statements that could be deemed to be forward- looking statements. These statements are based on current expectations, estimates, forecasts, and projections about the markets in which we operate and the beliefs and assumptions of our management. Words such as “aims,” "expects," "anticipates," "targets," "goals," "projects", "intends," "plans," "believes," "seeks," "estimates," "endeavors," "strives," "may," or variations of such words, and similar expressions are intended to identify such forward-looking statements. Readers are cautioned that the use of these forward-looking statements are subject to a number of risks, uncertainties and assumptions that are difficult to predict, estimate or verify. Therefore, actual results may differ materially and adversely from those expressed in any forward-looking statements. Such risks and uncertainties include (i) the Company’s ability to continue as a going concern; (ii) the risk that if the Company experiences delays or difficulties in the enrollment of patients in clinical trials, those clinical trials could take longer than expected to complete and the Company’s receipt of necessary regulatory approvals could be delayed or prevented; (iii) the risk that the Company will need additional capital to conduct its operations and develop its products, and the Company’s ability to obtain the necessary funding is uncertain; (iv) the risk that the Company’s common stock may be delisted in the future if the Company is unable to maintain compliance with continued listing requirements; (v) the risk that the Company’s products may fail to achieve necessary safety and efficacy endpoints during clinical trials, which may limit the company’s ability to general revenues from therapeutic products and (vi) those other factors described in our most recent annual report on Form 10-K, as such may be amended or supplemented by subsequent quarterly reports on Form 10-Q, or other reports filed with the Securities and Exchange Commission. Readers are cautioned not to place undue reliance on these forward-looking statements. The forward-looking statements are made only as of the date hereof, and we undertake no obligation to publicly release the result of any revisions to these forward-looking statements. For more information, please refer to our filings with the Securities and Exchange Commission. TriKE® is a registered trademark owned by GT Biopharma, Inc. Investor Relations Contact: LifeSci Advisors Corey Davis, Ph.D. [email protected] 212-915-2577 LinkedIn |Facebook |X |Instagram | YouTube

GTB-3650 TriKE® Phase 1 trial has successfully completed Cohort 1 and Cohort 2 dosing, treating a total of four patients; following Cohort 2’s formal safety review, it has advanced into Cohort 3 and initiated dosing of the fifth patient in the study; initial Phase 1 data expected later in 2025 GTB-5550 TriKE® IND submission for treatment of B7H3 positive solid tumors expected in Q4 2025; recent peer-reviewed publication highlights the pre-clinical anti-tumor activity of GTB-5550 against head and neck cancer Cash of approximately $5.3 million as of June 30, 2025, anticipated to be sufficient to fund operations into Q1 2026 SAN FRANCISCO, CALIFORNIA, Aug. 14, 2025 (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 natural killer (NK) cell engager TriKE® platform, today announced second quarter 2025 financial results for the period ended June 30, 2025. “We are pleased with the enrollment momentum in our Phase 1 clinical trial evaluating GTB-3650 in cancer patients, which continues to advance on schedule,” said Michael Breen, Executive Chairman and Chief Executive Office of GT Biopharma. "Moving into the third dose cohort after a successful safety review and encouraging early evidence of immunological activity, mark important steps forward in the development of GTB-3650. We look forward to sharing more data later this year to reinforce the ability of our TriKE constructs to activate endogenous NK cells, and the potential for broader utility with other targets to treat solid tumors (GTB-5550) and autoimmune indications (GTB-7550)." The Phase 1 dose escalation study is evaluating GTB-3650 in 12 patients (six cohorts) with relapsed or refractory (r/r) CD33 expressing hematologic malignancies, including refractory acute myeloid leukemia (AML) and high-risk myelodysplastic syndrome (MDS). GTB-3650 is dosed in two-week blocks, two weeks on and two weeks off, for up to four months based on clinical benefit. The trial will assess safety, pharmacokinetics, pharmacodynamics, in vivo expansion of endogenous patient NK cells and clinical activity. GT Biopharma plans on releasing more detailed results later in 2025 following enrollment and completion of additional dose cohorts. Second Quarter 2025 Financial Summary Cash Position: The Company had cash and cash equivalents of approximately $5.3 million as of June 30, 2025, anticipated to be sufficient to fund operations into Q1 2026. Research and Development (R&D) Expenses: R&D expenses for the second quarter ended June 30, 2025 were approximately $400,000 compared to $1.8 million for the same comparable quarter of 2024, the $1.4 million decrease was primarily due to a reduction in production and scientific research costs. Research and development expenses relate to our continued licensing, development and production of our most advanced TriKE® product candidates GTB-3650 and GTB-5550 along with the progression on other promising candidates. In late June 2024, we received clearance from the FDA with respect to our IND Application in relation to our next generation GTB-3650 camelid nanobody product. Study enrollment began in early 2025 and we have advanced into the clinic, enrolling patients, and performing tests for data collection throughout the year. Following our May 2025 financing we have restarted the final phase of product development of GTB-5550 and anticipate submission of an IND application for GTB-5550 in fourth quarter of 2025. Selling, General and Administrative (SG&A) Expenses (Excluding Stock Compensation): SG&A expenses for the second quarter ended June 30, 2025 were approximately $1.1 million compared to $2.0 million for the same comparable quarter of 2024, the $900,000 decrease was primarily due to a significant decrease in legal fees and other cost reduction measures. Net Loss: The Company reported a net loss of approximately $1.4 million for the second quarter ended June 30, 2025 compared to a net loss of $3.7 million for the same comparable quarter in 2024, the $2.3 million decrease consisted primarily of significant decreases in R&D and SG&A expenses (as described above). 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 Certain statements in this press release may constitute "forward-looking statements" regarding future events and our future results. All statements other than statements of historical facts are statements that could be deemed to be forward-looking statements. These statements are based on current expectations, estimates, forecasts, and projections about the markets in which we operate and the beliefs and assumptions of our management. Words such as "expects," "anticipates," "targets," "goals," "projects", "intends," "plans," "believes," "seeks," "estimates," "endeavors," "strives," "may," or variations of such words, and similar expressions are intended to identify such forward-looking statements. Readers are cautioned that these forward-looking statements are subject to a number of risks, uncertainties and assumptions that are difficult to predict, estimate or verify. Therefore, actual results may differ materially and adversely from those expressed in any forward-looking statements. Such risks and uncertainties include those factors described in our most recent annual report on Form 10-K, as such may be amended or supplemented by subsequent quarterly reports on Form 10-Q, or other reports filed with the Securities and Exchange Commission. Readers are cautioned not to place undue reliance on these forward-looking statements. The forward-looking statements are made only as of the date hereof, and we undertake no obligation to publicly release the result of any revisions to these forward-looking statements. For more information, please refer to our filings with the Securities and Exchange Commission. TriKE® is a registered trademark owned by GT Biopharma, Inc. Investor Relations Contact: LifeSci Advisors Corey Davis, Ph.D. [email protected] 212-915-2577