Zenas BioPharma, Inc. (ZBIO) announced that its registrational Phase 3 INDIGO trial of Obexelimab in Immunoglobulin G4-Related Disease (IgG4-RD) met its primary and all key secondary endpoints, marking a milestone for patients and the rheumatology community.
The data were presented at the EULAR 2026 Congress in London and simultaneously published in the New England Journal of Medicine.
Trial Results and Endpoints
The INDIGO study achieved statistically significant results across its primary and secondary endpoints. Obexelimab consistently reduced disease activity, flare burden, and glucocorticoid use, while lowering steroid-related toxicities. The therapy's safety profile was comparable to placebo, reinforcing confidence in its tolerability.
About Obexelimab
Obexelimab is a novel therapy with a unique inhibitory mechanism of action, potential for steroid sparing and, convenient at-home subcutaneous self-administration. It is designed to provide long-term disease management without the risks associated with chronic steroid use or sustained B-cell depletion.
Expert Commentary
Zenas CEO Lonnie Moulder highlighted the drug's potential as a first-line therapy, citing its unique inhibitory mechanisms, steroid-sparing benefits, and convenient at-home subcutaneous administration. Clinical experts noted that current treatment options for IgG4-RD are limited, and Obexelimab could provide a novel, self-administered alternative that avoids long-term steroid risks.
Lisa von Moltke, Zenas' CMO, emphasized that INDIGO is the largest clinical trial ever conducted in IgG4-RD, representing the most extensive dataset to support the clinical activity of any advanced therapy for this disease. She added that the trial strengthens evidence for targeting CD19 and Fc?RIIb in autoimmune diseases.
Regulatory and Pipeline Updates
A Biologics License Application (BLA) for Obexelimab in IgG4-RD was submitted to the FDA in May. Zenas also expects topline results from its Phase 2 SunStone SLE trial later this year, and is advancing ZB014, a half-life-extended antibody, toward clinical development.
ZBIO has traded between $8.91 and $44.60 over the past year. The stock closed Tuesday's trading at $17.13, down 5.72%. During afterhours trading, the stock is at $17.80, up 3.91%.
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