IgG4-RD is a debilitating chronic fibro-inflammatory disease affecting multiple organ systems, often resulting in irreversible tissue damage and organ failure. Obexelimab, an investigational therapy, is a bifunctional monoclonal antibody designed to bind both CD19 and FcgRIIb to inhibit B cell function.

"Our obexelimab BLA submission brings us one step closer to our goal of delivering this meaningful treatment option to patients living with IgG4-RD. Based on the significant clinical activity and the favorable safety and tolerability profile observed in the INDIGO study, we believe obexelimab may have an important role as a first line therapy in the long-term management of IgG4-RD," said Lisa von Moltke, M.D., Head of Research & Development & Chief Medical Officer of Zenas. "This regulatory submission marks a significant milestone for Zenas, and we would like to thank the patients, healthcare professionals and the Zenas team whose contributions made this submission possible."

The BLA submission is supported by the results of the Phase 3 INDIGO registrational trial of obexelimab for the treatment of IgG4-RD. In INDIGO, obexelimab met the primary endpoint, demonstrating a highly statistically significant and clinically meaningful 56% reduction in the risk of IgG4-RD flare compared to placebo (Hazard Ratio 0.44, p=0.0005) during the 52-week randomized placebo-controlled period. Obexelimab also met and demonstrated highly statistically significant activity compared to placebo on all four key secondary endpoints and was generally well tolerated. Data from the INDIGO trial will be presented during an oral session at the European Alliance of Associations for Rheumatology (EULAR) 2026 Congress in London, UK, on June 4, 2026.