The U.S. Food and Drug Administration approved Omeros Corp.'s narsoplimab (Yartemlea) for hematopoietic stem cell transplant‑associated thrombotic microangiopathy (TA‑TMA), making it the first therapy cleared for this life‑threatening transplant complication. The approval followed a Biologics License Application with a Dec. 26 PDUFA date and centers on a monoclonal antibody that inhibits mannan‑binding lectin‑associated serine protease‑2. Omeros designed the filing around clinical safety and efficacy data from transplant cohorts; the FDA decision clears a regulatory gap for clinicians treating TA‑TMA. Hospitals and transplant centers will now have an approved option where previously care relied on off‑label or supportive measures. The approval may also affect market access discussions for other complement and lectin‑pathway inhibitors in development for transplant complications.