Announcement • May 16
Gt Biopharma Inc Announces First Patient Dosed in Phase 1 Trial of Gtb-5550, A B7-H3-Targeted Natural Killer (Nk) Cell Engager for Solid Tumors GT Biopharma, Inc. announced that the first patient was dosed in a Phase 1 dose escalation basket trial evaluating GTB-5550, its B7-H3-targeted natural killer (NK) cell engager for solid tumors expressing B7-H3. GTB-5550 is now the 3rd TriKE to enter the clinic and an expansion into a broader solid tumor opportunity, with the Phase 1 trial likely to focus on prostate cancer patients during the dose escalation phase. The company anticipates providing updates in the second half of 2026 as enrollment progresses through dose escalation cohorts. The Phase 1 trial with GTB-5550 will be the first nanobody TriKE tested with more patient-friendly subcutaneous dosing. The Phase 1a dose escalation portion of the trial will focus primarily on enrolling prostate cancer patients and evaluate up to 6 dose levels to identify the maximum tolerated dose. 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 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 and overall survival. More details can be found on clinicaltrials.gov with the identifier: NCT07541573. New Risk • May 14
New major risk - Share price stability The company's share price has been highly volatile over the past 3 months. It is more volatile than 90% of American stocks, typically moving 17% a week. This is considered a major risk. Share price volatility increases the risk of potential losses in the short-term as the stock tends to have larger drops in price more frequently than other stocks. It may also indicate the stock is highly sensitive to market conditions or economic conditions rather than being sensitive to its own business performance, which may also be inconsistent. Currently, the following risks have been identified for the company: Major Risks Less than 1 year of cash runway based on free cash flow trend (-US$13m free cash flow). Share price has been highly volatile over the past 3 months (17% average weekly change). Shareholders have been substantially diluted in the past year (over 11x increase in shares outstanding). Revenue is less than US$1m. Market cap is less than US$10m (US$9.87m market cap). Minor Risk Currently unprofitable and not forecast to become profitable over next 3 years (US$11m net loss in 3 years). New Risk • Apr 26
New major risk - Market cap size The company's market capitalization is less than US$10m. Market cap: US$9.86m This is considered a major risk. Companies with a small market capitalization are most likely businesses that have not yet released a product to market or are simply a very small company without a wide reach. Either way, risk is elevated with these companies because there is a chance the product may not come to fruition or the company's addressable market or demand may not be as large as expected. In addition, if the company's size is the main factor, it is less likely to have many investors and analysts following it and scrutinizing its performance and outlook. Currently, the following risks have been identified for the company: Major Risks Less than 1 year of cash runway based on free cash flow trend (-US$13m free cash flow). Shareholders have been substantially diluted in the past year (over 11x increase in shares outstanding). Revenue is less than US$1m. Market cap is less than US$10m (US$9.86m market cap). Minor Risks Currently unprofitable and not forecast to become profitable over next 3 years (US$11m net loss in 3 years). Share price has been volatile over the past 3 months (12% average weekly change). 
