Zenas BioPharma Announces Late-Breaking Platform Presentation of Results from Phase 2 MoonStone Trial of Obexelimab in Relapsing Multiple Sclerosis at ACTRIMS Forum 2026

Core Insights - Obexelimab demonstrated a 95% relative reduction in new gadolinium-enhancing T1 lesions compared to placebo in the Phase 2 MoonStone trial, indicating significant efficacy in treating Relapsing Multiple Sclerosis (RMS) [1][2] - The 24-week data further confirmed the drug's robust and durable activity, maintaining significant reductions in lesions and improving biomarkers associated with disease activity [3][4] - The safety profile of obexelimab was consistent with previous trials, showing good tolerability without new safety signals [2][3] Company Overview - Zenas BioPharma, Inc. is a clinical-stage global biopharmaceutical company focused on developing transformative therapies for autoimmune diseases [12] - The company is advancing two late-stage product candidates: obexelimab and orelabrutinib, with obexelimab being the lead candidate targeting B cell activity [12] - Zenas plans to submit a Biologics License Application (BLA) for obexelimab in the second quarter of 2026 and a Marketing Authorization Application (MAA) in the second half of 2026 for Immunoglobulin G4-Related Disease [11][12] Clinical Trial Details - The Phase 2 MoonStone trial enrolled 116 patients and was designed to evaluate the efficacy and safety of obexelimab in RMS, using MRI endpoints to measure treatment outcomes [9] - The trial's primary endpoint was the cumulative number of new gad-enhancing T1 lesions over weeks 8 and 12, with secondary endpoints assessing disease progression through various biomarkers [9] - Following the double-blind phase, patients transitioned to an open-label period to continue treatment and assess long-term outcomes [9] Mechanism of Action - Obexelimab is a bifunctional monoclonal antibody that binds to CD19 and FcγRIIb, inhibiting B cell activity without depleting them, which is crucial for addressing autoimmune diseases [10][12] - The drug's unique mechanism and self-administered subcutaneous injection regimen may effectively target the pathogenic role of B cells in chronic autoimmune conditions [10][12]