Updated Data Provided From Phase 1/2 Trial Investigating GTB-3550 in Patients With MDS and AML

Updated data from a phase 1/2 clinical trial (NCT03214666) were announced showing that GTB-3550 was able to significantly reduce bone marrow blasts when used as therapy for certain patients with high-risk myelodysplastic syndromes (MDS) and refractory/relapsed acute myeloid leukemia (AML), according to a GT Biopharma, Inc. who is responsible for developing the therapy.

The focus of the trial is to investigate the end point of the maximum tolerated dose of GTB-3550.

“We are pleased with the continued clinical performance of our lead GTB-3550 TriKE [tri-specific killer engager] product candidate as we continue dose escalation,” Anthony Cataldo, Chairman and Chief Executive Officer of GT Biopharma, said in a press release. “These early data indicate GTB-3550 therapy demonstrates significant bone marrow blast level reductions in [patients with] AML and MDS without the need for expensive progenitor-derived or autologous/allogenic cell therapies.”

Up to this point, 9 patients have enrolled in the study, with the first 4 early enrolled patients treated with GTB-3550 below the anticipated therapeutic dose and maximum tolerated dose for safety considerations. This group of patients did not exhibit any toxicity.

The remaining patients were treated with GTB-3550 at increasing doses of 25 mcg/kg/day, 50 mcg/kg/day, and 100mcg/kg/day. More, 60% of participants experienced a reduction in bone marrow blasts, with that reduction being significant for 2 of the patients.

Specifically, the patient treated at the 50 mcg/kg/day dose level experienced a 61.7% reduction in bone marrow blast levels, while another patient treated at the 100 mcg/kg/day dose level achieved a 63.7% reduction. More, those 2 patients experienced a reduction from 12% before therapy to 4.6% after GTB-3550 therapy, and 22% before therapy to 8% after therapy, respectively.

None of the patients on the study experienced any grade of cytokine release syndrome.

“We believe as we continue to dose escalate GTB-3550 TriKE™, more patients will experience greater clinical efficacy. TriKE’s ability to work in the patient without outside supplemental engineered NK [natural killer] cells or the need for any combination drugs, sets TriKE apart from other cancer therapies,” explained Cataldo. “This is also the reason why TriKE therapy will be significantly less expensive than other treatments, opening the door to an off-the-shelf therapeutic.”

GTB-3550 is a TriKE product candidate from GT Biopharma initially developed to treat patients with AML. It’s a single-chain, tri-specific scFv recombinant fusion protein conjugate composed of anti-CD16 and anti-CD33 antibodies.

The GTB-3550 TriKE clinical trial is investigating patients with CD33+ malignancies aged 18 years or older. A number of correlative objectives for the research include the “number, phenotype, activation status, and function of NK cells and T cells.”

Reference:

GT Biopharma Announces Updated Interim GTB-3550 Trike™ Clinical Trial Results. News release. GT Biopharma. Published March 17, 2021. Accessed March 23, 2021. https://www.prnewswire.com/news-releases/gt-biopharma-announces-updated-interim-gtb-3550-trike-clinical-trial-results-301248091.html