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GTB-5550 for Advanced Solid Tumors

This study is testing a new treatment called GTB-5550 for people with advanced solid tumors. GTB-5550 is a type of immunotherapy that aims to help your body's natural killer (NK) cells fight cancer. You would receive GTB-5550 as a shot under the skin in your belly for 5 days, then have 2 weeks off, making a 4-week cycle. This is a first-in-human study to find the safest and most effective dose. To join, you must be 18 or older, have certain advanced solid tumors (like prostate, breast, pancreatic, lung, head and neck, ovarian, or bladder cancer) that have not responded to or cannot receive standard treatments, and have measurable disease.

Study design
This is a Phase 1a/1b interventional study that plans to enroll 175 participants. It is a first-in-human trial.
What's involved
You would receive GTB-5550 as a subcutaneous injection once a day for 5 consecutive days for 2 weeks, followed by 2 weeks of no treatment. This 4-week period is one treatment cycle.
Compensation
Not stated in the trial record.
Follow-up
The primary endpoint, maximum tolerated dose, will be measured at 1 year.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT07541573

GTB-5550 in Advanced Solid Tumors

Recruiting
PHASE1Ages 18+InterventionalTreatment
Masonic Cancer Center, University of Minnesota
~175 participants
Updated 2026-04-23 on ClinicalTrials.gov
What's tested:GTB-5550

At a glance

Recruiting sites
1 of 1 listed site is recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Maximum tolerated dose (MTD)
Measured over 1 year

Conditions

Tri-specific Killer Engager
Solid Tumor
Advanced Solid Tumor

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NCT07541573

Where you'd take part

This study runs at 1 site. They're the same protocol — you choose where, and that choice sets who your contact draft is addressed to.

  • Masonic Cancer Center at University of Minnesota

    Minneapolis, Minnesotano site contact published

    Recruiting

Sites open and close at different times, so the status above is per site — it can differ from the study's overall status.

Who to contact

Nicholas Zorko, MD
[email protected]
612-625-3051
Email the study team

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Eligibility criteria

Inclusion

Measurable disease per RECIST 1.1. (Exception: mCRPC limited to bone metastasis is exempt from this requirement).
Age 18 years or older at the time of consent, ECOG Performance Status 0 to 2
Acute effects of any prior therapy must have resolved to baseline or Grade ≤ 1 NCI CTCAE v5 except for AEs not constituting a safety risk in the opinion of the enrolling Investigator.
Adequate organ function within 14 days (30 days for cardiac) of Cycle 1 Day 1 defined as:
Hematologic: hemoglobin ≥ 9 g/dL (may be transfused not more than 2 units of pRBCs within 7 days prior to Cycle 1 Day 1 to meet this requirement); absolute neutrophil count (ANC) ≥ 1500/ul (granulocyte colonystimulating factor (s) is not allowed to achieve ANC threshold or within 7 days of Cycle 1 Day 1); platelets ≥ 100 x 10\^9/L (may be transfused not more than 2 units of platelets within 7 days prior to Cycle 1 Day 1 to meet this requirement); absolute lymphocyte count (ALC) ≥ 300/ul.
Albumin ≥ 3.0 g/dL.
Renal: a patient BSA corrected glomerular filtration rate ≥ 45 mL/min as calculated using the Modified Cockroft-Gault equation (Rostoker et al. 2007).
Hepatic: AST and ALT ≤1.5 x upper limit of normal (ULN) and total bilirubin ≤1.5 x ULN.
Cardiac: New York Heart Association (NYHA) Class I or II ; left ventricular ejection fraction (LVEF) ≥ 45% by echocardiogram, MUGA, or cardiac MRI.
Adequate pulmonary function with PFTs \> 50% FEV1 if symptomatic or known impairment.
Sexually active couples of childbearing-potential must agree to use effective contraception or abstinence during treatment and for at least 4 months after the final dose of GTB-5550.
Agrees to stay within a 60-minute drive of the study center through the Cycle 1 Day 15 visit for the Phase 1a study only.
Provides voluntary written consent prior to the performance of any research related activity

Exclusion

Anti-cancer treatment including surgery, radiotherapy, chemotherapy, other immunotherapy, or investigational therapy within 14 days prior to the 1st dose of GTB-5550. Radioligand therapy requires at least 1 cycle washout (6 weeks for Pluvicto, 4 weeks for Xofigo).
Prior organ allograft or allogeneic transplantation. An exception is made for FA patients with prior history of allogeneic hematopoietic stem cell transplant off immune suppressive therapy for \> 1 year.
Pregnant or breastfeeding or planning pregnancy within 4 months after the last dose of GTB-5550.
Prior malignancy other than the one under treatment except for the following: adequately treated basal cell or squamous cell skin cancer, in situ cervical cancer, adequately treated Stage I or II cancer which is currently in complete remission, or any other cancer from which the patient has been disease-free for 1 year after surgical or other definitive treatment.
Active autoimmune disease that has required systemic treatment (except replacement therapy) within the past 1 year or any other diseases requiring immunosuppressive therapy while on study. Inhaled or topical steroids, and adrenal replacement steroid doses ≤10 mg daily prednisone equivalent, are permitted in the absence of active autoimmune disease.
Active systemic infection requiring parenteral antibiotic therapy. Any prior systemic infections must have resolved to Grade 1 or lower following optimal therapy.
Psychiatric illness/social situations that in the judgement of the enrolling investigator would limit compliance with study requirements.
Other illness or a medical issue that, in the judgement of the enrolling Investigator, would exclude the patient's participation.

What this trial measures

  • Maximum tolerated dose (MTD)1 year

    The primary objective is to identify one of the six dose-level strategies of GTB-5550 (cam anti-CD16/WT IL 15/cam anti-B7-H3 TriKE) that corresponds to the desired maximum toxicity rate of less of equal to 20%, defining the MTD.