The FDA approved Omeros’s complement inhibitor Yartemlea to treat a severe, potentially fatal complication of hematopoietic stem‑cell transplants, marking the first approved therapy for this indication. The regulatory action follows Omeros’s submission and signals an important approval in transplant medicine and complement biology. Approval provides clinicians a targeted therapy for a previously unaddressed post‑transplant syndrome and establishes a commercial precedent for complement pathway drugs in transplant complications. Omeros will move to implement labeling, distribution and post‑marketing commitments required by regulators. Investors and transplant centers will monitor real‑world uptake, prescribing protocols, and payer coverage decisions that determine patient access. The approval also raises interest in complement inhibitors for other high‑unmet‑need indications.