The US FDA has approved narsoplimab for the treatment of hematopoietic stem cell transplant-associated thrombotic microangiopathy (TA-TMA) in adult and pediatric patients aged two years and older. TA-TMA is a severe and often fatal complication of stem cell transplantation, driven by activation of the lectin pathway of the complement system. Narsoplimab is the first and only approved inhibitor of the lectin pathway. It selectively targets mannose-binding lectin–associated serine protease-2 (MASP-2), the key effector enzyme of this pathway.
By inhibiting MASP-2, narsoplimab blocks lectin pathway activation while preserving the classical and alternative complement pathways, which are essential for host immune defense. This targeted mechanism is believed to prevent lectin pathway-mediated cellular damage, including endothelial injury in small blood vessels. Clinical evidence The efficacy…
