Transplant-associated thrombotic microangiopathy (TA-TMA) is a severe, often fatal complication of haematopoietic stem-cell transplantation, driven by endothelial injury and inappropriate complement activation — particularly the lectin pathway. For years its management relied on supportive care and off-label approaches (including modifying calcineurin inhibitors, which itself raises GVHD risk), with inconsistent results.
That changed at the end of 2025. Narsoplimab (Yartemlea), a monoclonal antibody that selectively inhibits MASP-2 — the effector enzyme of the lectin pathway — was FDA-approved in December 2025 for TA-TMA in adults and children aged two and older, becoming the first and only approved therapy for the condition and the first approved lectin-pathway inhibitor. In its clinical and expanded-access programs it produced complete-response rates around 61–68% and improved survival in high-risk patients, while preserving the classical and alternative complement pathways important for host defense. The C5 inhibitor eculizumab has also been used (off-label) in TA-TMA. With a targeted therapy now available, early recognition and risk stratification take on added importance.
Further reading: narsoplimab TA-TMA studies (Schoettler et al., Blood Advances 2025) and December 2025 FDA approval; TA-TMA pathophysiology and management (Lazana, 2023).