GT Biopharma Announces IND Submission for GTB-5550 TriKE®, a B7-H3-targeted natural killer (NK) cell engager for B7-H3 expressing solid tumor cancers

Rhea-AI Summary

GT Biopharma (NASDAQ: GTBP) submitted an IND for GTB-5550 to the FDA in December 2025 for a B7-H3-targeted TriKE designed to engage NK cells against B7-H3 expressing solid tumors. The company plans a Phase 1 basket trial in 2026 with a Phase 1a dose escalation (up to 7 dose levels to identify MTD) and a Phase 1b expansion across 7 metastatic cohorts. GTB-5550 uses dual camelid nanobody arms plus WT IL-15 and will be given subcutaneously on a 4-week cycle. Management reported a preliminary, unaudited cash balance of ~$7 million as of Dec 31, 2025, anticipated to extend runway into Q3 2026.

Positive

• IND submission for GTB-5550 completed in Dec 2025
• Planned Phase 1 basket trial initiation in 2026
• Preliminary cash balance of ~$7M as of Dec 31, 2025

Negative

• Cash runway only expected into Q3 2026
• GTB-5550 is at preclinical/early clinical stage with no clinical efficacy data yet

News Market Reaction

+10.61%

14 alerts

+10.61% News Effect

+15.4% Peak Tracked

-7.0% Trough Tracked

+$745K Valuation Impact

$8M Market Cap

0.3x Rel. Volume

On the day this news was published, GTBP gained 10.61%, reflecting a significant positive market reaction. Argus tracked a peak move of +15.4% during that session. Argus tracked a trough of -7.0% from its starting point during tracking. Our momentum scanner triggered 14 alerts that day, indicating notable trading interest and price volatility. This price movement added approximately $745K to the company's valuation, bringing the market cap to $8M at that time.

Data tracked by StockTitan Argus on the day of publication.

Key Figures

Global solid tumor market: $362 billion Preliminary cash balance: $7 million Cash runway: into Q3 2026 +5 more

8 metrics

Global solid tumor market $362 billion Estimated global solid tumor cancers market size

Preliminary cash balance $7 million Unaudited cash as of December 31, 2025

Cash runway into Q3 2026 Management’s anticipated operating runway

Phase 1 dose levels up to 7 Phase 1a dose escalation levels to identify MTD

Disease cohorts 7 cohorts Phase 1b metastatic solid tumor expansion groups

Dosing schedule 5 days in Week 1 and Week 2 Subcutaneous GTB-5550 administration per cycle

Treatment cycle length 4 weeks One full GTB-5550 treatment cycle duration

Follow-up period 12 months PFS and OS follow-up after treatment

Market Reality Check

Price: $0.4706 Vol: Volume 671,647 is below t...

low vol

$0.4706 Last Close

Volume Volume 671,647 is below the 20-day average of 2,030,430, indicating muted trading interest ahead of this news. low

Technical Shares at $0.66 are trading below the 200-day MA of $1.55 and sit 82.86% under the 52-week high.

Peers on Argus

Momentum scanner shows 2 peers moving down while GTBP was flagged as moving up, ...

2 Down

Momentum scanner shows 2 peers moving down while GTBP was flagged as moving up, suggesting stock-specific dynamics rather than a broad biotechnology move.

Historical Context

5 past events · Latest: Nov 19 (Positive)

Pattern 5 events

Date	Event	Sentiment	Move	Catalyst
Nov 19	Clinical pipeline update	Positive	+3.7%	Outlined GTB-3650 progress and GTB-5550 IND timing with cash update.
Nov 14	Earnings and update	Positive	+26.1%	Q3 2025 results plus GTB-3650 enrollment and GTB-5550 IND guidance.
Oct 23	Clinical trial update	Positive	+9.0%	GTB-3650 advanced to Cohort 4 after Cohort 3 safety review.
Oct 08	Clinical trial update	Positive	+43.7%	Reported smooth Cohort 3 enrollment with no dose-limiting toxicities.
Oct 06	Conference participation	Neutral	+10.6%	Announcement of CEO participation in investor summit and meetings.

Pattern Detected

Recent GTBP news, especially clinical updates, has often coincided with positive share reactions.

Recent Company History

Over the past few months, GT Biopharma has steadily advanced its NK cell engager pipeline. Multiple updates on the GTB‑3650 Phase 1 trial through October 2025 highlighted dose escalation with no major safety issues and biomarker activity, and each update saw positive price reactions. An earnings release on Nov 14, 2025 paired financials with clear clinical milestones and also drew a strong positive move. A conference participation announcement on Oct 6, 2025 similarly aligned with a gain. Today’s IND submission for GTB‑5550 extends that progression into solid tumors.

Market Pulse Summary

The stock surged +10.6% in the session following this news. A strong positive reaction aligns with G...

Analysis

The stock surged +10.6% in the session following this news. A strong positive reaction aligns with GT Biopharma’s history of favorable responses to clinical milestones, where past updates often saw gains of 8–44%. The IND submission for GTB‑5550 expands its TriKE platform into B7‑H3 solid tumors, supported by an unaudited cash balance of $7 million and runway into Q3 2026. Investors would still need to weigh going‑concern disclosures and prior Nasdaq deficiency notices when assessing durability.

Key Terms

investigational new drug (IND), natural killer (NK) cell, B7-H3, maximum tolerated dose (MTD), +4 more

8 terms

investigational new drug (IND) regulatory

"announced the submission of an investigational new drug (IND) application to the U.S."

An investigational new drug (IND) is a drug or biologic that is being tested but has not yet been approved for general use; it is the application and formal status that allows a company to begin human clinical trials under regulator oversight. Investors care because an IND marks the transition from lab work to human testing — like getting a permit to run real-world experiments — which creates important milestones, costs, timelines and regulatory risk that drive a development-stage company's value.

natural killer (NK) cell medical

"TriKE®, a B7-H3-targeted natural killer (NK) cell engager for the treatment"

A natural killer (NK) cell is a type of white blood cell in the immune system that acts like a rapid-response security guard, identifying and destroying infected or cancerous cells without prior training. For investors, NK cells matter because therapies or tests that harness, enhance, or measure them are central to many cancer and infectious disease treatments; progress or setbacks in NK-related products can affect clinical trial outcomes, regulatory decisions, and the commercial value of biotech firms.

B7-H3 medical

"GTB-5550 TriKE, a B7-H3-targeted natural killer (NK) cell engager"

B7‑H3 (CD276) is a protein that sits on the surface of certain cells, including many cancer cells, and can help tumors hide from the immune system—like a disguise that makes them harder for the body's defenses to spot. Investors watch B7‑H3 because medicines designed to block or use this protein aim to reveal tumors or deliver targeted therapy; progress in trials, regulatory clearances, or deals around B7‑H3 programs can materially change a biotech company's prospects and valuation.

maximum tolerated dose (MTD) medical

"dose escalation portion of the trial will test up to 7 dose levels to identify the maximum tolerated dose (MTD)."

Maximum tolerated dose (MTD) is the highest dose of an experimental drug that can be given to patients in early clinical testing without causing unacceptable or dangerous side effects. Investors watch the MTD because it frames whether a drug can reach effective levels safely, affects later trial design and approval chances, and influences expected development costs and market potential—like finding the fastest safe speed for a new vehicle before mass production.

subcutaneous (SQ) medical

"GTB-5550 will be administered by subcutaneous (SQ) injection in the abdominal area"

Subcutaneous (sq) indicates a drug or therapy given under the skin into the fatty layer just below the surface, typically by injection or small implant — imagine placing medicine into the cushion beneath your skin. The route matters to investors because it influences how fast and reliably a treatment works, its safety and convenience, required delivery devices, manufacturing complexity, and patient acceptance, all of which affect revenue, costs and regulatory risk.

metastatic medical

"across 7 distinct metastatic disease cohorts (castration-resistant prostate cancer, ovarian cancer,"

Metastatic describes cancer that has spread from its original spot to other organs or tissues, like weeds moving from one garden bed into several others. For investors, metastatic disease matters because it often requires more complex, long-term treatments, larger clinical trials, and can drive demand for specialized drugs and diagnostics—factors that affect a drug’s development costs, regulatory risk, market size, and potential revenue.

progression free survival (PFS) medical

"Patients are followed for 12 months to determine progression free survival (PFS) and overall survival (OS)."

Progression free survival (PFS) is the amount of time after a treatment starts during which a patient’s disease does not get worse. Investors watch PFS because it’s a commonly reported measure in clinical trials that can indicate a drug’s effectiveness earlier than overall survival, much like measuring how long a dam holds before leaks reappear; stronger PFS results can speed regulatory decisions and affect a drug’s commercial prospects.

overall survival (OS) medical

"months to determine progression free survival (PFS) and overall survival (OS)."

Overall survival (OS) is the length of time from the start of a treatment or clinical study until death from any cause, essentially measuring how long patients live after a therapy begins. Investors watch OS because it is the most direct evidence a treatment extends life; stronger OS results can drive regulatory approvals, wider use and higher revenue expectations, much like sales figures proving a product actually works.

AI-generated analysis. Not financial advice.

GT Biopharma targets a portion of the estimated $362 billion global solid tumor market

Preliminary, unaudited cash balance of approximately $7 million as of December 31, 2025 anticipated to extend cash runway into Q3 2026

SAN FRANCISCO, CALIFORNIA, Jan. 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 TriKE^® natural killer (NK) cell engager platform, today announced the submission of an investigational new drug (IND) application to the U.S. Food and Drug Administration (FDA) in December 2025 for GTB-5550 TriKE, a B7-H3-targeted natural killer (NK) cell engager for the treatment of B7-H3 expressing solid tumor cancers.

“The IND for GTB-5550 represents another NK cell engager we plan to move into clinical development and a tremendous accomplishment for the company”, said Michael Breen, Executive Chairman and Chief Executive Officer of GT Biopharma. “As we continue actively enrolling the Phase 1 trial with GTB-3650 in myeloid blood cancer, we expect the next data readout in 1H 2026 could provide potential evidence of clinical activity. Initiation of a Phase 1 basket trial with GTB-5550 for multiple solid tumors is planned for 2026. We look forward to applying the clinical learnings from the GTB-3650 study to help inform the GTB-5550 program, which targets a patient population with B7-H3 expressing solid tumors that is orders of magnitude larger than the myeloid blood cancer patient population.” The global market for B7-H3 expressing solid tumor cancers accounts for a portion of the estimated $362 billion global solid tumor cancers market (according to Data Bridge Market Research). B7-H3 expressing solid tumor cancers are estimated to account for a significant portion of solid tumor cancers.

GTB-5550 is a camelid (cam) anti-CD16/WT IL-15/cam anti-B7-H3 tri-specific natural killer (TriKE) cell engager, with a single chain recombinant TriKE comprised of three components joined by flexible linkers: 1) a nanobody arm that engages the CD16 activating receptor (camelid anti-CD16) on natural killer (NK) cells; 2) a wildtype IL-15 (WT IL-15) linker arm to drive NK cell proliferation, priming, and survival; and 3) a nanobody arm that specifically engages B7-H3 (camelid anti-B7-H3) to target the antigen expressed on tumor cells.

Based on supportive preclinical data, the planned Phase 1 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 7 dose levels to identify the maximum tolerated dose (MTD). The Phase 1b dose expansion component of the trial will confirm the MTD identified in the Phase 1a trial across 7 distinct 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 tolerability assuming the toxicity rates are similar across the groups.

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).

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.
cdavis@lifesciadvisors.com
212-915-2577

LinkedIn |Facebook |X |Instagram | YouTube

FAQ

What did GT Biopharma (GTBP) file with the FDA in December 2025?

GT Biopharma submitted an IND for GTB-5550, a B7-H3-targeted TriKE, in December 2025.

When will GTBP start the Phase 1 trial for GTB-5550?

A Phase 1 basket trial is planned for 2026, with Phase 1a dose escalation followed by Phase 1b expansion.

What dosing schedule will be used in the GTB-5550 Phase 1 trial (GTBP)?

GTB-5550 will be given subcutaneously 5 consecutive days in Week 1 and Week 2, then 2 weeks off (4-week cycle).

Which tumor types will GTBP include in the GTB-5550 Phase 1b expansion?

Seven metastatic cohorts: prostate, ovarian, breast, head and neck, non-small cell lung, pancreatic, and bladder cancer.

How much cash did GT Biopharma report and how long will it last?

Management reported a preliminary, unaudited cash balance of ~ $7 million as of Dec 31, 2025, anticipated to extend runway into Q3 2026.