FDA Approves Narsoplimab-wuug for Transplant-Associated Thrombotic Microangiopathy

The FDA approved nasoplimab-wuug (Yartemlea; Omeros Corporation) for the treatment of patients with transplant-associated thrombotic microangiopathy (TA-TMA).

Narsoplimab is an investigational, fully human monoclonal antibody that targets mannan-binding lectin-associated serine protease-2 (MASP-2), a novel proinflammatory protein target and the effector enzyme of the lectin pathway of complement. Crucially, the inhibition of MASP-2 has been demonstrated to leave intact the antibody-dependent classical complement activation pathway, which is a significant part of the acquired immune response to infection.²

"Based on a compelling data package, narsoplimab delivers robust response rates and improved survival in TA-TMA, with a favorable benefit-risk profile and a safety profile consistent with that seen in patients undergoing hematopoietic stem cell transplantation," said Miguel-Angel Perales, MD, chief of the Adult Bone Marrow Transplantation Service at Memorial Sloan Kettering Cancer Center, in a news release. "As the first and only drug approved for TA-TMA, narsoplimab is a practice-changing advance for patients facing this devastating complication."¹

A biologics license application (BLA) for the use of narsoplimab in the treatment of hematopoietic stem cell TA-TMA was resubmitted to the FDA in March 2025. The resubmission of this BLA was based on analysis results that showed clinically meaningful and statistically significant improvements in survival associated with narsoplimab treatment, according to a May 2025 news release. Previously, narsoplimab was granted FDA breakthrough therapy and orphan drug designations for TA-TMA and an orphan drug status for the prevention or inhibition of complement-mediated thrombotic microangiopathies.²

Research findings published in Bone Marrow Transplant in 2024 demonstrated the effective use of narsoplimab in pediatric and adult patients with high-risk TA-TMA in a real-world setting. Twenty patients were enrolled between January 2018 and August 2023, of whom 13 were adults and 7 were pediatric patients. In this group, 15 patients fulfilled the criteria recently established by an international consensus on TA-TMA, and 19 exhibited high-risk characteristics.³

The findings indicated that about 65% (n = 13) of the enrolled patients responded to narsoplimab and achieved transfusion independence and significant clinical improvement. The 100-day overall survival (OS) following TA-TMA diagnosis was approximately 70% and 100% for responders. Narsoplimab proved to be effective and safe in the treatment of high-risk TA-TMA, with no increased infectious complications or other safety signals of concern across all age groups.³

Further, a 2025 real-world study published in Wiley’s American Journal of Hematology showed that 1-year OS in pediatric patients with high-risk TA-TMA who were allogeneic recipients and received narsoplimab as a first-line therapy (n = 12) was about 75.0%, and 56.2% in those who received narsoplimab as a second- or later-line therapy (n = 25). For adults, 1-year OS in allogeneic patients with high-risk TA-TMA who received narsoplimab as first-line therapy (n = 49) was approximately 58.0%, and 40.5% in those who received narsoplimab as a second- or later-line therapy (n = 16). There were no concerning safety signals.⁴

"This approval is a long-awaited breakthrough in hematopoietic cell transplantation and TA-TMA care," Perales said. "Until now, we've lacked an effective TA-TMA therapy and relied largely on supportive measures such as modifying calcineurin inhibitors, which can significantly increase the risk of life-threatening graft-versus-host disease."¹

REFERENCES

1. FDA approves Omeros' Yartemlea – first and only therapy indicated for TA-TMA. News release. Omeros. December 24, 2025. Accessed December 24, 2025. https://www.businesswire.com/news/home/20251224065139/en/FDA-Approves-Omeros-YARTEMLEA-First-and-Only-Therapy-Indicated-for-TA-TMA

2. Omeros. FDA Accepts Resubmission of BLA for Narsoplimab for Hematopoietic Stem Cell Transplant-Associated Thrombotic Microangiopathy (TA-TMA) and Assigns Late September PDUFA Date. News release. May 6, 2025. Accessed September 24, 2025. https://investor.omeros.com/news-releases/news-release-details/fda-accepts-resubmission-bla-narsoplimab-hematopoietic-stem-cell

3. Castelli M, Micò MC, Grassi A, et al. Safety and efficacy of narsoplimab in pediatric and adult patients with transplant-associated thrombotic microangiopathy: a real-world experience. Bone Marrow Transplant 59, 1161–1168 (2024). doi:10.1038/s41409-024-02305-3

4. Schoettler ML, Pusarla SK, Nangia N, et al. Narsoplimab Results in Excellent Survival in Adults and Children With Hematopoietic Cell Transplant Associated Thrombotic Microangiopathy (TA-TMA). Am J Hematol. Published online August 29, 2025. doi:10.1002/ajh.70044