Zenas BioPharma Shares Plummet After Phase 3 INDIGO Trial for Obexelimab in IgG4-Related Disease Meets Endpoint but Falls Short of Expectations

Zenas BioPharma's Phase 3 INDIGO trial for obexelimab in IgG4-related disease met the primary endpoint, reducing flare-up risk by 56% vs. placebo, but underperformed compared to Amgen's Uplizna (87% reduction).12

Company shares crashed over 50% to around $17 pre-market following the Monday readout announcement.15

Zenas plans to file a U.S. biologics license application for obexelimab in IgG4-RD in Q2 2026.12

Upcoming data includes Phase 2 MoonStone results in relapsing multiple sclerosis in Q1 2026 and Phase 2 in systemic lupus erythematosus by late 2026.13

Sources:

1. https://www.biospace.com/drug-development/zenas-plummets-after-late-stage-data-fall-short-of-amgen-in-inflammatory-disease

2. https://www.biopharmadive.com/news/zenas-obexelimab-IgG4-indigo-study-results/808718/

3. https://zenasbio.com/our-science/pipeline/

5. https://www.thepharmaletter.com/biotechnology/zenas-biopharma-tanks-on--phase-iii-obexelimab-trial-results