Bexmarilimab Gains FDA Orphan Drug Designation for AML


The phase 1/2 BEXMAB study is investigating the combination of bexmarilimab with standard of care in patients with hematologic malignancies.

The FDA has granted an orphan drug designation (ODD) to bexmarilimab (FP-1305) for the treatment of patients with acute myeloid leukemia (AML).1

Currently, the phase 1/2 BEXMAB study (NCT05428969) is investigating the combination of bexmarilimab with standard of care (SOC) for the treatment of aggressive hematological malignancies, including relapsed/refractory (R/R) AML and myelodysplastic syndromes (MDS). Three dosing cohorts are being assessed (1, 3 and 6 mg/kg).2,3

Positive findings from phase 1 of the study were previously reported and showed that 3 of 5 patients treated with 6 mg/kg bexmarilimab with azacitidine had an objective response of complete remission of blasts in the bone marrow. One of those 3 patients also achieved a complete recovery of blood counts.

Blood cells in a bone marrow biopsy © Катерина Євтехова - []

Blood cells in a bone marrow biopsy © Катерина Євтехова - []

Additionally, 8 of 15 overall responses were observed across all 3 doublet dosing cohorts with 4 of 8 patients across the 3 doublet dosing cohorts having failed SOC hypomethylating agents (HMAs). Each of the 3 patients with MDS and prior HMA failure demonstrated overall responses across dosing cohorts. Further, objective responses have been seen in 4 of 6 patients in the triplet dosing cohort treated with azacitidine, venetoclax and bexmarilimab.

“Receiving orphan drug designation from the FDA signifies our continued progress and commitment to develop bexmarilimab as a potential treatment for AML,” said chief medical officer Marie-Louise Fjällskog, MD, in a press release. “The designation represents a milestone in our development journey, one that we believe when combined with standard of care, will lead to better patient outcomes and improved quality of life.”

The multicenter, open-label, phase 1/2 BEXMAB study has an estimated enrollment of 181 patients aged 18 years and older with morphologically confirmed diagnosis of MDS, CMML-2 with indication for azacitidine treatment, CMML and MDS patient with response failure to HMA or therapy regimen including HMA, AML following at least 1 line of prior therapies with indication for azacitidine treatment, or AML in patients unfit for induction therapy with indication for azacitidine-venetoclax treatment. Patients must also have a leukocyte count < 20 x109/L (< 25 x109/L for newly diagnosed AML), and adequate renal and liver function to be included in the study.3

In phase 1 of the study, investigators aim to identify a safe and tolerable dose of bexmarilimab and the maximum tolerated dose (MTD) of bexmarilimab when administered in combination with SOC. Part 22 will utilize an expansion phase to further assess the safety and efficacy of bexmarilimab treatment when given at the recommended phase 2 dose (RP2D) in combination with SOC. Phase 2 of the trial will also include patients from phase 1 who have been treated at RP2D.

Both phases of the study will include a screening period, a treatment period, an end of treatment as safety follow-up and disease progression/survival follow-up.

Primary end points of the study include dose-limiting toxicities, frequency, and severity of adverse events (AEs) and serious AEs, complete response rate, overall response rate, complete remission with incomplete blood recovery for R/R AML, and minimal residual disease for newly diagnosed AML. Safety, clinical efficacy based on progression-free survival and overall survival analyses, anti-bexmarilimab antibody positivity occurrence rate pre-dose and at defined time points during treatment, and serum concentrations of bexmarilimab will be evaluated as secondary end points.

The completion of the dose-escalation phase of the study, readout of enrichment cohorts, and the initiation of the phase 2 are expected towards the end of 2023.1

  1. Faron receives FDA orphan drug designation for bexmarilimab in acute myeloid leukemia. News release. Faron Pharmaceuticals Ltd. August 29, 2023. Accessed August 30, 2023.
  2. Faron updates positive clinical data from phase I/II BEXMAB study of bexmarilimab in relapsed/refractory AML and MDS BEXMAB study update. News release. Faron Pharmaceuticals Ltd. July 19, 2023. Accessed August 30, 2023.
  3. A study to assess safety, tolerability and preliminary efficacy of bexmarilimab in combination with standard of care in patients with hematological malignancies (BEXMAB). Updated June 23, 2023. Accessed August 30, 2023.
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