Biomea Fusion Announces Preliminary Data from Ongoing COVALENT-103 Study of Investigational Covalent FLT3 Inhibitor BMF-500 in Relapsed or Refractory Acute Leukemia

On December 9, 2024 Biomea Fusion, Inc. ("Biomea" or "the company") (Nasdaq: BMEA), a clinical-stage biopharmaceutical company dedicated to discovering and developing novel covalent small molecules to treat and improve the lives of patients with genetically defined cancers and metabolic diseases, reported preliminary data from the ongoing Phase I COVALENT-103 study evaluating BMF-500, the company’s investigational covalent FLT3 inhibitor developed using the proprietary FUSION System (Press release, Biomea Fusion, DEC 9, 2024, View Source [SID1234648892]).

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"These early findings from the COVALENT-103 study announced today highlight the potential of BMF-500 to deliver meaningful clinical benefits for patients with acute leukemia harboring a FLT3 mutation. BMF-500 is an exceptionally potent molecule and the second covalent inhibitor we have developed in-house and advanced to the clinic and has shown high target selectivity and inhibition," said Thomas Butler, CEO of Biomea Fusion. "Our early results are particularly exciting as FLT3 gene mutations are common in AML patients and are associated with a very poor prognosis. Patients with such mutations who have failed gilteritinib have a median overall survival of less than 2 months. We hope to provide a significant improvement in the outcome for these patients with BMF-500. Given the safety profile demonstrated to date, and the lack of myelosuppression, we think BMF-500 could be an excellent combination partner used in standard of care."

As of the data cut off, November 20, 2024, 20 patients with R/R acute leukemia had been enrolled in the dose-escalation portion of the study, all of whom received at least one dose of BMF-500. Among these, the study enrolled 13 patients with confirmed FLT3-mutations, of which 10 harbored FLT3-ITD mutations and 3 had FLT3-TKD mutations. All patients with FLT3-mutations had progressed following treatment with gilteritinib, and 5 had received at least 2 prior FLT3 inhibitors. The study enrolled 5 patients with wild-type FLT3 and 2 patients with an unknown FLT3 mutation status. The median number of prior lines of therapies among the enrolled patients was 4. No QT prolongations or related cytopenias were observed and no dose-limiting toxicities (DLTs) were reported as of the data cut off. BMF-500 was generally well tolerated, and dose escalation is continuing per protocol.

Pharmacokinetic/pharmacodynamic data confirmed on-target FLT3 inhibition, as BMF-500 and its metabolites showed bone marrow penetration and near complete FLT3 inhibition as early as Day 1 of dosing, as well as dose-proportional FLT3 inhibition.

Preliminary data supports BMF-500’s potential as a transformative therapy for patients with FLT3 mutated R/R acute leukemia. During dose escalation, BMF-500 achieved a first CRi at the end of Cycle 2, in 1 of 2 (50%) FLT3 mutated patients dosed at 100 mg twice daily (BID), while the other patient experienced a clearance of peripheral blasts, greater than 50% reduction in bone marrow blasts and reduced transfusion frequency. The majority (5 of 6) of efficacy evaluable FLT3-mutated patients experienced a reduction of their bone marrow blasts. Other evidence of clinical activity such as: clearance or reduction of peripheral blasts, reduction of transfusion frequency, reduction in use of hydroxyurea were observed.

Case Study Highlights of Patient with Complete Response (CRi)

61-year-old patient with R/R AML, post allogenic transplant, with six co-occurring mutations (FLT3-ITD, ASXL1, IDH2, PHF6, RUNX1, SRSF2)
4 prior treatment regimens including venetoclax and gilteritinib
Confirmed CRi at 100 mg BID dosing
Progressive improvement in normal white blood cells, neutrophils, and monocytes despite ongoing transfusion needs
Webcast and Conference Call Details

Biomea Fusion will host a webcast and conference call today, Monday, December 9 at 4:30 pm EST. Interested parties will be able to join the webcast and view the related presentation under the Investors and Media section of the company’s website at View Source A replay of the webcast and conference call will be archived on Biomea’s website following the event.

About COVALENT-103

COVALENT-103 is a multicenter, open-label, non-randomized trial seeking to evaluate the safety and efficacy of BMF-500, a twice daily oral treatment, in adult patients with relapsed or refractory acute leukemia with FMS-like tyrosine kinase 3 (FLT3) wild-type and FLT3 mutations. The Phase I COVALENT-103 study aims to evaluate the safety and tolerability of BMF-500, determine the optimal biologic dose and recommended Phase II dose. Additional information about the Phase I clinical trial of BMF-500 can be found at ClinicalTrials.gov using the identifier, NCT05918692.

About BMF-500

BMF-500, an investigational, novel, orally bioavailable, highly potent and selective covalent small molecule inhibitor of FLT3, was discovered and developed in-house at Biomea using the company’s proprietary FUSION System and has demonstrated encouraging potential based on extensive preclinical studies. The kinase inhibitory profile of BMF-500 showed high target selectivity, suggesting the potential for reduced off-target liabilities. BMF-500 was designed to have a therapeutic profile to allow for combinations with standard of care and/or novel targeted agents like icovamenib, Biomea’s investigational covalent menin inhibitor currently in clinical development for solid and liquid tumors as well as diabetes.

Previous data presented at the 2022 American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting showed BMF-500’s picomolar affinity for inhibition of activating FLT3 mutations, including FLT3-ITD and various tyrosine kinase domain (TKD) mutations. BMF-500 demonstrated multi-fold higher potency and increased cytotoxicity as compared to the commercially available non-covalent FLT3 inhibitor gilteritinib. These data also showed complete tumor regression in mouse models of FLT3-ITD acute myeloid leukemia (AML), with no tumor regrowth even after treatment cessation.

Data presented at the 2023 American Association for Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting demonstrated the potential utility of combination strategies to achieve higher antileukemic cell killing with reduced concentrations of BMF-500 and icovamenib. Additionally, Biomea has shown the potential of combinatorial approaches of BMF-500 and icovamenib with MEK and BCL2 blockade in other preclinical studies. These data provide preclinical evidence for combining pathway-specific inhibitors as a potential therapeutic strategy for further investigation in acute leukemia.

About FLT3 in AML

FLT3 is a receptor tyrosine kinase (RTK) that plays a central role in the survival, proliferation, and differentiation of immature blood cells. FLT3 gene mutations are common in patients with AML and are associated with a poor prognosis. Nearly 40% of AML patients have a FLT3 mutation, representing more than 7,000 incident patients in the U.S. each year. Once failing the only approved agent in the R/R setting, gilteritinib, patients typically have a poor prognosis and very short survival (median overall survival ~1.8 months). Academic literature suggests that up to 50% of AML patients with an NPM1 mutation also harbor a FLT3 mutation. While FLT3-specific and pan-tyrosine kinase inhibitors are approved by the FDA across various lines of therapy in AML, these agents have produced relatively low rates of durable responses and overall survival remains an unmet need.