Narsoplimab: First Approval.

Narsoplimab (narsoplimab-wuug; YARTEMLEA®) is a recombinant human immunoglobulin G4 monoclonal antibody targeted against mannan-binding lectin-associated serine protease 2 (MASP-2) being developed by Omeros Corporation initially for the treatment of haematopoietic stem cell transplantation (HCT)-associated thrombotic microangiopathy (TA-TMA). MASP-2 inhibition by narsoplimab is thought to provide benefit in patients with TA-TMA by decreasing or preventing lectin complement pathway-mediated cellular injury. In December 2025, narsoplimab received its first approval, in the USA, for the treatment of adult and paediatric patients aged ≥ 2 years with TA-TMA. Additionally, a Marketing Authorisation Application for narsoplimab for the treatment of TA-TMA is currently under regulatory review in the EU. This article summarises the milestones in the development of narsoplimab leading to this first approval for TA-TMA.