The FDA approved Omeros’s complement inhibitor Yartemlea to treat a severe, often fatal complication of hematopoietic stem cell transplants. This marks the first approved therapy for the condition and provides clinicians with a targeted option to interrupt complement‑mediated pathology after transplant. Regulatory documents and the company briefing show that Yartemlea’s approval was based on clinical efficacy in a defined post‑transplant population. The decision will influence hospital transplant protocols and could spur follow‑on development of complement modulators for other inflammatory conditions.