Obexelimab - (INDIGO)

June 2, 2026: Zenas BioPharma (NASDAQ: ZBIO) reported additional Phase 3 INDIGO data for obexelimab in IgG4-related disease (IgG4-RD), presented at EULAR 2026 and published online by the New England Journal of Medicine. The company said a BLA for obexelimab in IgG4-RD was submitted to the FDA in May.

In the 194-patient trial, weekly subcutaneous obexelimab met the primary endpoint, reducing risk of IgG4-RD flare by 56% vs placebo over 52 weeks (HR 0.44; 95% CI 0.277-0.711; p=0.0005); 73.2% remained flare-free at Week 52 vs 45.4% on placebo. All four key secondary endpoints were also met: 59% lower risk of investigator-determined flare requiring rescue therapy (HR 0.41; p=0.0001), 52% lower annualized adjudicated flare rate (36 vs 72 flares; HR 0.48; p=0.0008), higher complete remission at Week 52 (37.1% vs 19.6%; p=0.0049), and lower cumulative glucocorticoid rescue use (329.5 mg vs 929.8 mg; p=0.0042).

Glucocorticoid toxicity worsening was lower with obexelimab, and safety was described as comparable to placebo, with lower Grade ≥3 TEAEs (11.3% vs 23.7%) and serious adverse events (10.3% vs 18.6%). Upcoming catalyst: topline Phase 2 SunStone SLE results, including biomarker data, are expected in Q4 2026.