This section highlights FDA-related milestones and regulatory updates for drugs developed by GT Biopharma (GTBP).
Over the past two years, GT Biopharma has reported clinical trial outcomes, regulatory submissions, approvals, and other FDA events for drugs and therapies such as
GTB-5550 and GTB-3650. For definitions of regulatory abbreviations such as NDA, BLA, or PDUFA, see the event status legend.
Select a button below to view the list of FDA events for that drug.
GTB-5550 FDA Regulatory Events
GTB-5550 is a drug developed by GT Biopharma for the following indication: Multiple Myeloma.
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- GTB-5550
- Announced Date:
- May 14, 2026
- Indication:
- Multiple Myeloma
Announcement
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.
AI Summary
GT Biopharma said the first patient has been dosed in a Phase 1 basket trial of GTB-5550, a B7-H3-targeted natural killer (NK) cell engager for solid tumors. The study is a dose-escalation trial, and the company expects the early part of enrollment to focus mainly on prostate cancer patients. GTB-5550 is the third TriKE® product to reach clinical testing, and it marks an expansion into a wider solid tumor program. The company said it plans to share updates in the second half of 2026 as patients move through the dose-escalation cohorts.
According to the company, metastatic castration-resistant prostate cancer often shows B7-H3 in more than 90% of tumors, making it a strong target for the therapy. PSA may also help signal early treatment activity. GT Biopharma said it looks forward to testing GTB-5550 across several solid tumor types during the trial.
Read Announcement- Drug:
- GTB-5550
- Announced Date:
- February 3, 2026
- Indication:
- Multiple Myeloma
Announcement
GT Biopharma, Inc. announced FDA clearance of its IND application for GTB-5550, allowing the company to proceed with a Phase 1 clinical trial, which is anticipated to initiate in mid-2026.
AI Summary
GT Biopharma announced the U.S. Food and Drug Administration has cleared its investigational new drug (IND) application for GTB-5550, allowing the company to start a Phase 1 clinical trial. This clearance permits GT Biopharma to move forward with human testing of GTB-5550, an investigational therapy targeting tumors that express the B7-H3 protein.
The planned study is a Phase 1 dose-escalation basket trial that will include multiple solid tumor types known to express B7-H3. The design will assess safety, tolerability, and early signs of activity across tumor cohorts. GT Biopharma expects the trial to initiate in mid-2026.
As of January 31, 2026, the company reported an unaudited proforma cash balance of about $9 million, which it anticipates will fund operations through the fourth quarter of 2026. GT Biopharma will use the upcoming trial to gather initial human data on GTB-5550’s clinical potential.
Read Announcement
GTB-3650 FDA Regulatory Timeline and Events
GTB-3650 is a drug developed by GT Biopharma for the following indication: For Treatment of CD33+ Leukemia.
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- GTB-3650
- Announced Date:
- November 19, 2025
- Indication:
- For Treatment of CD33+ Leukemia
Announcement
GT Biopharma is advancing a proprietary platform designed to harness NK cells against cancer. Its main candidate, GTB 3650, is currently being tested in Phase 1 trials for patients with relapsed or refractory acute myeloid leukemia, and the company is also working on treatments Early clinical progress and multiple upcoming milestones position GTBP as a notable player in the evolving immuno-oncology market.
AI Summary
GT Biopharma is developing a proprietary NK cell engager platform that aims to harness a patient’s natural killer (NK) cells to attack cancer. Its lead candidate, GTB 3650, is in a Phase 1 dose‑escalation trial for relapsed or refractory acute myeloid leukemia and other CD33‑positive blood cancers. Early cohorts (six patients across cohorts 1–3) have completed treatment with no major tolerability issues, and investigators reported increased NK cell activity and favorable immunologic biomarkers. GTB 3650 is given as a 72‑hour continuous infusion in two‑week cycles to evaluate safety, pharmacokinetics, pharmacodynamics, NK expansion, and early clinical signals.
GT Biopharma is also advancing GTB 5550, a B7H3‑targeting TriKE planned for IND filing in late 2025 or early 2026 with subcutaneous dosing for solid tumors, and GTB 7550, a CD19‑targeting program in preclinical development. Early clinical progress and several upcoming dose‑escalation and regulatory milestones position GTBP as a notable player in the growing NK cell immuno‑oncology field.
Read Announcement- Drug:
- GTB-3650
- Announced Date:
- October 23, 2025
- Target Action Date:
- Q1 2026
- Estimated Target Date Range:
- January 1, 2026 - March 31, 2026
- Indication:
- For Treatment of CD33+ Leukemia
Announcement
GT Biopharma, Inc. announced that Next update expected in Q1 2026, as well as continued dose escalation (up to 100ug/kg/day) in 3 additional cohorts if necessarypositive trend in observations on multiple immunological biomarkers from the previous six patients in Cohorts 1 through 3, the absence of dose limiting toxicities, and the associated lower dose levels
AI Summary
GT Biopharma recently completed the formal safety review of Cohort 3 (5 µg/kg/day) in its Phase 1 trial of GTB-3650, with no safety or tolerability issues observed. This milestone allowed the company to advance into Cohort 4 at a higher dose of 10 µg/kg/day, thought to be closer to a clinical efficacy threshold. Patients are now being actively screened for this next cohort, and dosing is expected to begin in the coming weeks.
Early data from the first six patients across Cohorts 1–3 showed a positive trend in multiple immunological biomarkers, and there were no dose-limiting toxicities at the lower dose levels. The study protocol allows dose escalation in up to three additional cohorts, potentially reaching 100 µg/kg/day if needed to maximize therapeutic effect.
GT Biopharma anticipates providing the next update on its GTB-3650 trial in Q1 2026.
Read Announcement- Drug:
- GTB-3650
- Announced Date:
- October 23, 2025
- Indication:
- For Treatment of CD33+ Leukemia
Announcement
GT Biopharma, Inc announced successful completion of the Cohort 3 formal safety review with no safety or tolerability issues observed and advancement into Cohort 4 of its Phase 1 dose escalation trial evaluating GTB-3650 for the treatment of relapsed or refractory (r/r) CD33 expressing hematologic malignancies.
AI Summary
GT Biopharma, Inc. announced the successful completion of the Cohort 3 safety review in its Phase 1 dose escalation trial of GTB-3650, with no safety or tolerability issues observed. GTB-3650 uses the TriKE® natural killer cell engager platform to target relapsed or refractory CD33-expressing blood cancers.
The trial now moves to Cohort 4 with a 10 µg/kg/day dose, closer to potential efficacy levels after positive trends in immunological biomarkers and absence of dose-limiting toxicities. Patients are being actively screened, and dosing is expected to start in the coming weeks.
The protocol includes up to seven cohorts, with dose levels up to 100 µg/kg/day if needed. Each treatment cycle is two weeks on drug followed by two weeks off, for up to four months based on clinical benefit. GT Biopharma plans its next update in Q1 2026 as the trial progresses.
Read Announcement- Drug:
- GTB-3650
- Announced Date:
- October 8, 2025
- Indication:
- For Treatment of CD33+ Leukemia
Announcement
GT Biopharma announced that enrollment in the dose escalation cohorts of the Phase 1 trial, evaluating GTB-3650 for the treatment of relapsed or refractory (r/r) CD33 expressing hematologic malignancies, is well on track.
AI Summary
GT Biopharma, Inc. announced that enrollment in the dose escalation cohorts of its Phase 1 trial of GTB-3650 is well on track. The study is testing GTB-3650 in patients with relapsed or refractory CD33-expressing blood cancers, aiming to find a safe and effective dose.
Enrollment in Cohorts 1 and 2 wrapped up successfully, and both patients in Cohort 3 have now begun treatment with no dose-limiting toxicities or tolerability concerns reported. Biomarker analysis in the first Cohort 3 patient showed immune activation similar to levels seen in earlier cohorts. The protocol allows up to seven dose tiers with two patients each.
After Cohort 3’s safety review, dosing in Cohort 4 is planned by the end of 2025, with flexibility to escalate up to Cohort 7 if needed. The company expects to share additional data by the first quarter of 2026 as it seeks the optimal dose to drive meaningful therapeutic activity.
Read Announcement- Drug:
- GTB-3650
- Announced Date:
- August 11, 2025
- Indication:
- For Treatment of CD33+ Leukemia
Announcement
GT Biopharma, Inc announced initiation of dosing in Cohort 3 of its Phase 1 dose escalation trial evaluating GTB-3650 for the treatment of relapsed or refractory (r/r) CD33 expressing hematologic malignancies.
AI Summary
GT Biopharma, Inc. announced it has begun dosing patients in Cohort 3 of its Phase 1 GTB-3650 trial. This study tests GTB-3650 in patients with relapsed or refractory CD33+ blood cancers. The first patient in Cohort 3 completed week one of cycle one with no safety issues after Cohorts 1 and 2 passed safety reviews.
Early data from the first four patients show GTB-3650 can activate natural killer cells. Blood tests indicate the drug spurs NK cell expansion and immune activity. These signals suggest the treatment may work as intended.
GT Biopharma plans to report initial results in 2025 after more dose groups finish. The study will enroll 14 patients in seven cohorts. GTB-3650 is given in two-week on, two-week off cycles for up to four months. The trial will measure safety, pharmacokinetics, pharmacodynamics, NK cell growth and clinical response (NCT06594445).
Read Announcement- Drug:
- GTB-3650
- Announced Date:
- May 19, 2025
- Indication:
- For Treatment of CD33+ Leukemia
Announcement
GT Biopharma Tells Benzinga Co. Advances GTB-3650 Phase I Trial To Cohort 2 Following Successful Initial Human Dosing And Evidence Of Early Immune Activation Signals
AI Summary
GT Biopharma recently announced progress in its Phase I clinical trial for GTB-3650, a second-generation TriKE therapy targeting CD33-expressing blood cancers. The company successfully completed dosing for Cohort 1, reporting no safety or tolerability issues, which allowed the trial to advance to Cohort 2. Early biomarker analysis from Cohort 1 revealed increased immunologic activity, showing that natural killer (NK) cells were activated and expanded, a promising sign for the therapy’s potential effectiveness.
Moving forward, the trial will continue to assess safety, dosing parameters, and immune responses across multiple cohorts and involve up to 14 patients over a four-month period. GT Biopharma plans to present more detailed results in 2025, underscoring the company’s commitment to advancing its immuno-oncology treatments and providing hope for patients with challenging hematologic malignancies.
Read Announcement- Drug:
- GTB-3650
- Announced Date:
- January 27, 2025
- Indication:
- For Treatment of CD33+ Leukemia
Announcement
GT Biopharma, Inc announced that the first patient was dosed in a Phase 1 trial evaluating GTB-3650, its second-generation TriKE, for the treatment of relapsed or refractory (r/r) CD33 expressing hematologic malignancies.
AI Summary
GT Biopharma recently announced a significant milestone in its new treatment development by dosing the first patient in a Phase 1 trial. The study is testing GTB-3650, their second-generation TriKE, for patients with relapsed or refractory blood cancers that express the CD33 protein. GTB-3650 is designed to help the body’s own natural killer cells fight cancer more effectively. In the trial, up to 14 patients will be treated using a regimen where the drug is given for two weeks followed by a two-week break, over a period of up to four months. Researchers will closely monitor the treatment's safety, how it works in the body, and the response of the patients' immune cells. The company looks forward to sharing initial results from the trial in 2025, marking a hopeful step for new cancer treatment options.
Read Announcement- Drug:
- GTB-3650
- Announced Date:
- January 27, 2025
- Indication:
- For Treatment of CD33+ Leukemia
Announcement
GT Biopharma, Inc announced that Initial data from the Phase 1 trial expected in 2025
AI Summary
GT Biopharma, Inc. has begun dosing patients in a Phase 1 trial for its new therapy, GTB-3650, which is developed to treat certain blood cancers. The trial targets relapsed or refractory cancers that express the CD33 marker, such as acute myeloid leukemia. GTB-3650 is a second-generation therapy that uses a special technology to boost the activity of the body’s natural killer cells against cancer cells. In this trial, around 14 patients will receive the treatment in cycles, with dosing periods set for two weeks on and two weeks off. The company is excited to advance this study and plans to share the first set of results in 2025, marking an important step forward in their efforts to develop new cancer treatments.
Read Announcement
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