Zenas BioPharma reported that obexelimab met the primary endpoint in its Phase 3 Indigo study for IgG4-related disease, but the topline 56% reduction in flare risk compared unfavorably to Amgen’s recently approved Uplizna. The company said it will seek FDA approval, but investors sold off stock after the cross-trial contrast and lower-than-expected effect size. On an investor call Zenas executives highlighted potential differentiators—such as a non‑depleting B‑cell mechanism that may suit older patients—and argued for clinical niches where obexelimab could be preferred, while acknowledging the competitive landscape set by Amgen’s data.