The FDA approved Omeros’s complement inhibitor Yartemlea to treat a life‑threatening complication of hematopoietic stem cell transplants. This is the first regulatory approval for the indication, giving clinicians an evidence‑based option for a previously untreatable post‑transplant syndrome. The decision will affect transplant centers, payors and Omeros’s commercial strategy, and it may prompt follow‑on development of complement pathway agents. Regulatory documents and the approval label will clarify dosing, trial endpoints and safety surveillance expectations for broad clinical use.