Positive Phase 3 INDIGO Trial Results in IgG4-related disease (IgG4-RD)

Progress in IgG4-related disease (IgG4-RD) has always depended on rigorous clinical trials and the willingness of patients, families, clinicians and researchers to move the field forward together. For a rare and complex disease, generating high-quality evidence is never easy, but it is essential.

Zenas BioPharma’s announcement of positive results from the Phase 3 INDIGO trial marks an important step in that ongoing effort. The INDIGO trial studied obexelimab – a novel medication – for its ability to maintain disease remissions in IgG4-RD. INDIGO compared obexelimab plus a short prednisone taper to a placebo plus the same prednisone taper.

The INDIGO investigators found that obexelimab reduced the risk of disease flare over one year by 56%.

INDIGO, the largest clinical trial conducted in adults living with IgG4-RD to date, met its primary endpoint with highly statistically significant results, providing strong evidence that this therapeutic approach can benefit people living with IgG4-RD.

Clinical trials of this scale do not succeed by chance. INDIGO was made possible by patients who participated despite uncertainty, caregivers and families who supported them, investigators and healthcare teams across multiple sites, and sustained engagement from the broader IgG4-RD community.

Based on these results, Zenas has announced plans to submit a Biologics License Application (BLA) to the U.S. FDA in Q2 of 2026, with a Marketing Authorization Application (MAA) to the European Medicines Agency planned for the second half of 2026. While regulatory review and access considerations remain ahead, completion of a Phase 3 registrational trial is a critical milestone for the field.