The U.S. Food and Drug Administration (FDA) has officially approved Yartemlea (narsoplimab), marking a historic milestone for the 31-year-old biotech firm Omeros. This decision introduces the first specific treatment for a life-threatening complication associated with stem cell transplants.
Medical Breakthrough Yartemlea is recognized as the first-in-class lectin pathway inhibitor indicated for hematopoietic stem cell transplant-associated thrombotic microangiopathy (TA-TMA). This condition often leads to widespread endothelial dysfunction and multi-organ injury.
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Mechanism of Action: The drug selectively targets the MASP-2 enzyme, blocking harmful activation while preserving the essential complement functions required for host defense.
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Patient Population: Approved for patients aged 2 years and older.
The Path to Approval Following an initial rejection in 2021 due to the lack of a control group, Omeros resubmitted its application using comparative data between clinical trial participants and an external registry of patients who did not receive the treatment.
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Clinical Efficacy: Complete response rates were observed between 61% and 68%, characterized by improved platelet counts and organ function.
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Survival Rates: The 100-day survival rate following a TA-TMA diagnosis reached approximately 73% to 74% among treated patients.
Commercial Outlook Omeros plans to launch Yartemlea in the United States in January 2026. Furthermore, the company expects a regulatory decision for the European market by mid-2026. To fuel this commercial launch, Omeros recently divested another pipeline candidate to Novo Nordisk in a deal valued at up to $2.1 billion.