Zenas Biopharma’s obexelimab hit the primary endpoint in the Phase III Indigo trial for immunoglobulin G4‑related disease but the magnitude of benefit compared unfavorably to Amgen’s recently approved Uplizna, triggering a steep share drop. The randomized data showed a statistically significant reduction in flare risk versus placebo, yet investors focused on cross‑trial efficacy comparisons and Amgen’s higher benchmark, sending Zenas stock sharply lower. Zenas plans a BLA submission in the second quarter and highlighted potential clinical differentiators—such as a non‑depletionary B‑cell modulation approach—that it believes could support market niche strategies. The readout underscores how cross‑trial context and recent approvals can reshape commercial expectations even when primary endpoints are met.