Zenas BioPharma Touts Phase 3 Win, But Stock Crashes

Core Viewpoint - Zenas BioPharma Inc. stock is experiencing a decline despite positive results from the Phase 3 INDIGO trial of obexelimab for Immunoglobulin G4-Related Disease (IgG4-RD) [1][4]. Group 1: Trial Results - Obexelimab achieved the primary endpoint with a statistically significant 56% reduction in the risk of IgG4-RD flare compared to placebo over a 52-week period [2]. - The drug also met all four key secondary endpoints, showing significant activity in reducing investigator-assessed IgG4-RD flare, the number of flares requiring rescue therapy, the proportion of patients achieving complete remission, and the cumulative use of rescue therapy [3]. Group 2: Safety and Future Plans - Rates of infections, including Grade 3, were lower in the obexelimab group compared to placebo, with similar incidence of injection site reactions across both groups [4]. - Zenas plans to submit a Biologics License Application (BLA) for obexelimab to the FDA in Q2 2026 and a Marketing Authorization Application (MAA) to the EMA in the second half of 2026 [7]. - The company expects to report topline results from the Phase 2 SunStone trial in SLE in Q4 2026 [8]. Group 3: Competitive Landscape - Amgen's Uplizna, the first approved treatment for IgG4-RD, demonstrated an 87% reduction in flare risk compared to placebo, with 10.3% of participants experiencing a flare versus 59.7% in the placebo group [5]. - Amgen acquired Uplizna through a $27.8 billion acquisition of Horizon Therapeutics [6].