FDA Grants Orphan Drug Designation to Bexmarilimab for AML


The FDA has granted an orphan drug designation to bexmarilimab for the treatment of patients with acute myeloid leukemia.

Marie-Louise Fjällskog, MD, PhD

Marie-Louise Fjällskog, MD, PhD

The FDA has granted an orphan drug designation to bexmarilimab (FP-1305) for the treatment of patients with acute myeloid leukemia (AML), according to an announcement from Faron Pharamceuticals.1

Bexmarilimab is an investigational immunotherapy intended to help overcome resistance to existing treatment options through the targeting of myeloid cell function and the ignition of the immune system. The agent is designed target the Clever-1 receptor on macrophages in order to alter the tumor microenvironment, reprogram macrophages from an immunosuppressive (M2) state to an immunostimulatory (M1) state, upregulate interferon production, prime the immune system to attack tumors, and sensitize cancer cells to standard of care (SOC).

“Receiving orphan drug designation from the FDA signifies our continued progress and commitment to develop bexmarilimab as a potential treatment for AML,” Marie-Louise Fjällskog, MD, PhD, chief medical officer of Faron Pharamceuticals, stated in a news 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 ongoing phase 1/2 BEXMAB trial (NCT05428969) is evaluating bexmarilimab in combination with SOC azacitidine or azacitidine plus venetoclax (Venclexta) in patients with relapsed/refractory AML and myelodysplastic syndrome (MDS). Updated data from the study showed that among 5 patients treated with 6 mg/kg of bexmarilimab plus azacitidine, 3 patients experienced an objective response of complete remission (CR) of blasts in the bone marrow (mCR).2 One of these 3 patients also had complete blood count recovery.

Additionally, across the 3 doublet dosing cohorts of 1 mg/kg, 3 mg/kg, and 6 mg/kg of bexmarilimab, 8 of 15 objective responses were reported. Four of those 8 patients were failed by standard hypomethylating agents (HMAs), and all 3 patients with MDS and previous HMA failure achieved an objective response, including 1 patient each with a partial response, mCR, and CR.

In the triplet dosing cohort evaluating bexmarilimab plus azacitidine and venetoclax, 4 of 6 patients achieved an objective response.

The ongoing, open-label, non-randomized phase 1/2 trial is enrolling patients at least 18 years of age with morphologically confirmed intermediate-, high- and very high–risk MDS per the revised International Prognostic Scoring System; chronic myelomonocytic leukemia (CMML)–2 with indication for azacitidine treatment; CMML or MDS that did not respond to an HMA or a regimen including an HMA; relapsed/refractory AML following at least 1 line of prior therapy with an indication for azacitidine; or AML that is unfit for induction therapy with indication for azacitidine/venetoclax treatment.3

All patients need to have a leukocyte count of less than 20 x 109/L, except for those with newly diagnosed AML, who must have a leukocyte count of less than 25 x 109/L. Adequate renal and liver function are also required.

Patients with acute promyelocytic leukemia or myeloproliferative CMML are excluded from the study. An ECOG performance status of more than 2 is not allowed; however, patients less than 75 years of age with newly diagnosed AML are allowed to have an ECOG performance status of 3. An allogeneic stem cell transplant less than 6 months prior screening is not allowed.

Patients with frontline MDS/CMML, CMML/MDS following HMA failure, or relapsed/refractory AML are receiving bexmarilimab once per week plus SOC azacitidine. Those with newly diagnosed AML unfit for induction chemotherapy are being given 1mg/kg of bexmarilimab once per week plus SOC azacitidine and venetoclax.4

The primary objectives for the study included the incidence of dose-limiting toxicities, treatment-emergent and serious adverse effects (AEs), CR rate for patients with MDS/CMML-2, overall response rate for those with MDS/CMML following HMA failure, CR with incomplete blood recovery rate for patients with relapsed/refractory AML, and minimal residual disease status for those with newly diagnosed AML.3

In prior data presented at the 2023 EHA Congress, 5 of 10 patients treated with bexmarilimab plus azacitidine across all indications experienced an objective response, and a reduction in bone marrow blasts was observed in more than 50% of patients.4

Regarding safety, no DLTs or serious AEs related to bexmarilimab were reported. Additionally, no patients experienced grade 3 or higher AEs related to bexmarilimab or discontinued treatment due to AEs related to bexmarilimab.

Treatment-related AEs (TRAEs) of any grade were reported in 50% of patients (n = 5). The most common grade 1/2 TRAEs included constipation (20%), nausea (10%), pyrexia (10%), and vomiting (10%).


  1. Faron receives FDA orphan drug designation for bexmarilimab in acute myeloid leukemia. News release. Faron Pharmaceuticals. August 29, 2023. Accessed August 29, 2023. https://otp.tools.investis.com/clients/uk/faron2/rns/regulatory-story.aspx?cid=2223&newsid=1711777
  2. Faron updates positive clinical data from phase I/II BEXMAB study of bexmarilimab in relapsed/refractory AML and MDS. News release. Faron Pharmaceuticals. July 19, 2023. Accessed August 29, 2023. https://otp.tools.investis.com/clients/uk/faron2/rns/regulatory-story.aspx?cid=2223&newsid=1703177
  3. A study to assess safety, tolerability and preliminary efficacy of bexmarilimab in combination with standard of care in patients with hematological malignancies (BEXMAB). ClinicalTrials.gov. Updated June 23, 2023. Accessed August 29, 2023. https://classic.clinicaltrials.gov/ct2/show/NCT05428969
  4. Kontro M, Siitonen T, Rimipilainen J, et al. A phase I/II study to assess safety, tolerability and preliminary efficacy of bexmarilimab in combination with standard of care in patients with myeloid malignancies (BEXMAB). Presented at: 2023 EHA Congress; June 8-11, 2023; Frankfurt, Germany. Abstract P542.
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