Bexmarilimab Responses in High-Risk MDS Continue to Improve

Updated efficacy data from the phase 1/2 BEXMAB study (NCT05428969) evaluating bexmarilimab plus standard of care showed an increased complete remission (CR) rate in patients with frontline or treatment-naive high-risk myelodysplastic syndrome (MDS).¹

The CR rate increased to 43% (n = 9/21) according to investigator-assessed response per IWG 2006 criteria compared with the original 28% from an earlier data cut. This updated data was prepared in anticipation of an end-of-phase 2 meeting between Faron Pharmaceuticals, the sponsor, and the FDA.

“The continued maturation of the BEXMAB data demonstrates bexmarilimab’s profound impact as a disease-modifying agent,” said Petri Bono, MD, chief medical officer of Faron Pharmaceuticals, in a press release. “Seeing the CR rate strengthen over time to 43%, which complements the robust 50% cCR we have already reported, is very encouraging. It provides us with 2 compelling and clinically meaningful data sets for discussion with the FDA and gives us confidence in proposing a randomized registrational trial designed for accelerated approval with either CR or cCR as the primary end point.”

About the BEXMAB Study

BEXMAB is a phase 1/2 study evaluating bexmarilimab combined with standard-of-care therapy in patients with MDS, chronic myelomonocytic leukemia, or acute myeloid leukemia.² The study enrolled patients across 10 sites in the US, Finland, and the United Kingdom, and patients received bexmarilimab with azacitidine and/or venetoclax (Venclexta).

The study’s primary end point was incidence of dose-limiting toxicities, incidence of adverse events, CR rate, overall response rate, CR with incomplete blood recovery, and measurable residual disease status. Secondary end points included progression-free survival, overall survival, anti-bexmarilimab antibody positivity, and serum concentrations of bexmarilimab.

To be eligible for study enrollment, patients were required to have adequate leukocyte counts, renal function, and hepatic function. Those with an ECOG status greater than 2 or an active autoimmune disorder or who had received an allogeneic transplantation within 6 months were not eligible for participation.

About Bexmarilimab

Bexmarilimab is an investigational immunotherapy that aims to overcome resistance to existing treatments and optimize clinical outcomes.³ This is done by targeting myeloid cell function and igniting the immune system. binding to Clever-1, an immunosuppressive receptor that is seen on macrophages, leading to tumor growth and metastases. When the Clever-1 receptor is targeted, bexmarilimab changes the tumor microenvironment, reprogramming macrophages from an immunosuppressive to an immunostimulatory state.

In March 2025, the FDA granted the agent orphan drug designation for the treatment of patients with MDS.

Regarding safety, data published in The Lancet Haematology from the dose-escalation phase of BEXMAB showed that the most common grade 3 to 4 treatment-emergent adverse events (AEs) were febrile neutropenia (n = 8 [24%]), anemia (n = 7 [21%]), and thrombocytopenia (n = 5 [15%]).⁴ Treatment-emergent deaths occurred as a result of sepsis (n = 1 [3%]), neutropenic infection (n = 1 [3%]), and hemophagocytic lymphohistiocytosis (n = 1 [3%]). Four patients presented treatment-related serious AEs: 1 patient in the 1.0 mg/kg group, 2 in the 3.0 mg/kg group, and 1 in the 6.0 mg/kg group. These included rash (grade 3), capillary leak syndrome (grade 3), cryptogenic organizing pneumonia (grade 3), and hemophagocytic lymphohistiocytosis (grade 5), which led to 1 death.

REFERENCES:

1. Inside Information: Faron to present updated BEXMAB data in frontline HR-MDS to FDA; complete remission rate substantially increased to 43%. News release. Faron Pharmaceuticals. August 6, 2025. Accessed August 7, 2025. https://tinyurl.com/mt6usmph

2. 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 May 31, 2025. Accessed August 7, 2025. https://clinicaltrials.gov/study/NCT05428969

3. Inside information: FDA grants orphan drug designation for bexmarilimab in MDS. News release. Faron Pharmaceuticals. March 3, 2025. Accessed August 6, 2025. https://tinyurl.com/4356vnnc

4. Kontro M, Stein AS, Pyörälä M, et al. Bexmarilimab plus azacitidine for high-risk myelodysplastic syndrome and relapsed or refractory acute myeloid leukaemia: results from the dose-escalation part of a multicentre, single-arm, phase 1/2 trial. Lancet Haematol. 2025 Jul;12(7):e516-e528. doi: 10.1016/S2352-3026(25)00103-6. Epub 2025 May 28.