The FDA granted approval to Omeros’s complement inhibitor Yartemlea as the first therapy for a severe, potentially fatal complication arising after hematopoietic stem‑cell transplantation. The approval marks an initial regulatory win for complement pathway modulation in post‑transplant care and is likely to alter clinical treatment protocols for transplant centers managing this complication. Complement inhibitors target a cascade of immune proteins that can drive destructive inflammation; clinicians will evaluate safety, dosing and real‑world uptake as hospitals begin to integrate the drug into post‑transplant algorithms.