Zenas Biopharma reported positive topline results from its Phase 3 Indigo trial of obexelimab in immunoglobulin G4‑related disease (IgG4‑RD) but investors reacted sharply after comparing effect size with a recent Amgen competitor. Obexelimab met the primary endpoint with a statistically significant reduction in flare risk versus placebo, yet the magnitude of benefit fell short of the benchmark set by Amgen’s Uplizna in an earlier trial; Zenas said it will file a BLA in Q2. The readout underscores how cross‑trial comparisons shape market sentiment and near‑term valuation for rare‑disease immunotherapies.