Obexelimab - (INDIGO)

October 12, 2026: Zenas BioPharma (NASDAQ: ZBIO) reported new obexelimab data in IgG4-related disease (IgG4-RD) at the 6th International Symposium on IgG4-Related Disease (October 8-10, 2026). In the Phase 3 INDIGO open-label extension, patients received obexelimab 250 mg subcutaneously once weekly; the 12-month probability of remaining flare-free was 0.93 based on investigator- and adjudication committee-confirmed flares requiring rescue therapy and 0.87 based on investigator-determined flares, with five patients pending adjudication. Median cumulative glucocorticoid rescue dose was 0 mg and mean was 105 mg; adverse event rates were comparable to or lower than the randomized period.

A Phase 3 INDIGO sub-analysis found obexelimab significantly reduced cumulative glucocorticoid toxicity versus placebo at week 52 using the Glucocorticoid Toxicity Index (GTI Cumulative Worsening Score difference -11.4; p=0.021), with fewer patients reaching clinical toxicity thresholds.

In an ongoing vaccine sub-study during a planned treatment-free window, seroimmunity was seen in 6/7 (86%) for influenza and 4/4 (100%) for COVID-19; no disease flares occurred during the average 34.6-day window. Zenas also said topline results from the Phase 2 SunStone trial of obexelimab in SLE are expected in 4Q 2026.