CAMBRIDGE, Mass., Sept. 23, 2025 (GLOBE NEWSWIRE) -- Biogen Inc. (Nasdaq: BIIB) today announced that the U.S. Food and Drug Administration (FDA) issued a Complete Response Letter (CRL) for the Company’s supplemental New Drug Application (sNDA) for the high dose regimen of nusinersen for the treatment of spinal muscular atrophy (SMA). The FDA letter requested an update to the technical information be included in the Chemistry Manufacturing and Controls (CMC) module of the sNDA.
The letter did not cite any deficiencies in the clinical data of the high dose regimen. The FDA provided options for resolution, and Biogen is planning to resubmit the application promptly based upon readily available information.
“While this outcome was unexpected, we remain committed to bringing the high dose regimen to people living with SMA,” said Priya Singhal, M.D., M.P.H., Head of Development at Biogen. “We are working diligently to provide the necessary information to the FDA.”
Biogen is working with regulatory authorities around the world to advance the high dose regimen as an additional dosing option for people living with SMA. The high dose regimen of SPINRAZA (nusinersen) was recently approved in Japan and is actively under review by the European Medicines Agency (EMA) and other global regulators.
About SPINRAZA
SPINRAZA (nusinersen) 12mg/5 mL injection is approved in more than 71 countries to treat infants, children and adults with spinal muscular atrophy (SMA). As a foundation of care in SMA, more than 14,000 individuals have been treated with SPINRAZA worldwide.1
SPINRAZA has shown efficacy across ages and SMA types with a well-established safety profile based on data in patients treated up to 10 years,2,3 combined with unsurpassed real-world experience. The most common adverse events observed in clinical studies were respiratory infection, fever, constipation, headache, vomiting and back pain. Laboratory tests can monitor for renal toxicity and coagulation abnormalities, including acute severe low platelet counts, which have been observed after administration of some ASOs.
Biogen licensed the global rights to develop, manufacture and commercialize SPINRAZA from Ionis Pharmaceuticals, Inc. (Nasdaq: IONS). Please click here for Important Safety Information and full Prescribing Information for SPINRAZA in the U.S., or visit your respective country’s product website.
About Biogen
Founded in 1978, Biogen is a leading biotechnology company that pioneers innovative science to deliver new medicines to transform patients’ lives and to create value for shareholders and our communities. We apply deep understanding of human biology and leverage different modalities to advance first-in-class treatments or therapies that deliver superior outcomes. Our approach is to take bold risks, balanced with return on investment to deliver long-term growth.