Zenas BioPharma announces positive Phase 3 results for obexelimab in IgG4-related disease

Zenas BioPharma (NASDAQ:ZBIO), a clinical-stage global biopharmaceutical company focused on developing transformative immunology-based therapies for autoimmune diseases, today announced positive topline results from the Phase 3 INDIGO registrational trial evaluating obexelimab in patients with Immunoglobulin G4-Related Disease (IgG4-RD).

Obexelimab, a bifunctional monoclonal antibody that inhibits B cell function without depletion, met the primary endpoint with a highly statistically significant and clinically meaningful 56% reduction in the risk of disease flare compared to placebo over the 52-week randomized period (Hazard Ratio 0.44; p=0.0005).

The trial also achieved statistical significance on all four key secondary endpoints, including reductions in investigator-assessed flares, flares requiring rescue therapy, cumulative rescue therapy use, and the proportion of patients reaching complete remission

Additionally, obexelimab demonstrated a favorable safety profile, with lower rates of infections (including Grade 3) versus placebo and comparable injection site reactions.

Meanwhile, no new safety signals emerged.

IgG4-RD is a chronic immune-mediated condition that can cause fibro-inflammatory lesions in multiple organs, leading to irreversible damage if untreated.

Current treatments are limited, highlighting a significant unmet need.

Zenas plans to submit a Biologics License Application (BLA) to the U.S. FDA in the second quarter of 2026 and a Marketing Authorization Application (MAA) to the European Medicines Agency in the second half of 2026.

Full INDIGO data will also be presented at an upcoming medical conference.