EMA Refuses Marketing Authorization for Narsoplimab
The drug, approved in the US, failed to meet efficacy requirements in the European Union for treating a transplant-related condition.
Updated on Oct. 21, 2026 in Biotech
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The European Medicines Agency (EMA) has formally rejected a marketing authorization application for the drug narsoplimab, intended to treat hematopoietic stem cell transplant-associated thrombotic microangiopathy. Following a final negative opinion, the manufacturer intends to terminate its EU compassionate-use program for the medication.
Why it matters
The rejection highlights stringent European requirements for clinical evidence, as the EMA concluded that the submitted data failed to prove a treatment benefit. While the drug is already approved for use in the United States, its path forward in the European market remains uncertain due to study design limitations.
Narsoplimab functions by blocking mannan-binding lectin-associated serine protease-2 to mitigate complement-mediated endothelial injury. The EMA committee determined that the study data, which lacked a control group and included patients receiving concomitant medications, failed to meet efficacy benchmarks.
The players
European Medicines Agency
The decentralized agency of the European Union responsible for the scientific evaluation, supervision, and safety monitoring of medicines.
Omeros Ireland Limited
A pharmaceutical company focused on the development of products for inflammatory and immunologic diseases and disorders of the central nervous system.
The details
Narsoplimab is administered via intravenous infusion to address complications following stem cell transplants. The drug targets the lectin pathway of the complement system—a part of the immune system that enhances the ability of antibodies and phagocytic cells to clear microbes and damaged cells—to prevent the clotting and damage associated with microangiopathy. The EMA cited concerns regarding the study's lack of a control group and the use of other medications, which hindered the ability to isolate the drug's therapeutic effect.
Timeline
November 2018: Narsoplimab received orphan designation in the European Union.
December 2025: The FDA approved narsoplimab for the United States market.
June 25, 2026: The EMA committee issued an initial negative opinion.
October 15, 2026: The committee adopted the final negative opinion.
The Tech Race
The EMA's decision marks a departure from the regulatory outcome in the United States, where the drug received approval in December 2025. This divergence underscores the differing evidentiary demands between these two major pharmaceutical markets.
Patients currently utilizing narsoplimab through the European compassionate-use program will see this access terminated. No new patients will be able to access the medication through this specific European pathway following the committee's final negative opinion.
The takeaway
The EMA's firm rejection demonstrates the significant hurdle that study design limitations pose for drugs already cleared in other regions. Interested parties should monitor updates regarding Omeros Ireland Limited's ongoing clinical trial assessments for potential future submissions.
Further reading
For broader trends in drug development and regulatory challenges, see Biotech.
Source note: This article includes information reported by Medscape.
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