Regeneron Gains Dual FDA and EMA Acceptance for Cemdisiran NDA in Generalized Myasthenia Gravis

Regulatory affairs teams tracking the siRNA modality now have a concrete timeline to work against: Regeneron Pharmaceuticals has secured simultaneous NDA acceptance from the FDA and EMA for cemdisiran in adult patients with anti-acetylcholine receptor (AChR) antibody-positive generalized myasthenia gravis (gMG), positioning the asset as a potential first-in-class siRNA approval for this indication.

The FDA accepted the submission under Priority Review, following use of a Priority Review Voucher, with a target action date of November 2026. The EMA acceptance sets a European Commission decision on a separate timeline, anticipated in the second half of 2027. A regulatory filing in Japan is planned for early 2027, extending the submission cycle across three major markets within roughly 18 months.

The applications are supported by data from the Phase 3 NIMBLE trial, described as one of the largest global interventional gMG studies conducted to date. Cemdisiran is dosed subcutaneously every 12 weeks, a four-times-yearly regimen that distinguishes it from existing complement-pathway therapies. Full NIMBLE data were published simultaneously in The Lancet and presented at the American Academy of Neurology Annual Meeting in April 2026. The trial enrolled adults with symptomatic gMG who may also be receiving standard-of-care immunosuppressants at investigator discretion.

For manufacturing and QA leads, the siRNA modality carries distinct process validation and sterility assurance considerations relative to monoclonal antibody platforms. Subcutaneous delivery at a low-frequency dosing interval places particular emphasis on formulation stability and container-closure integrity across the product's shelf life. Regeneron holds sole responsibility for development, manufacturing, and commercialization of cemdisiran as monotherapy and in combination with C5 antibodies, under a worldwide licensing agreement with Alnylam.

gMG affects an estimated 150 to 200 per million people globally, with approximately 85,000 patients in the U.S. The disease mechanism centers on abnormal anti-AChR antibodies activating the complement system, including C5, disrupting neuromuscular transmission. Approximately 85% of MG patients progress from initial ocular symptoms to generalized disease affecting muscles throughout the body. Current treatment gaps include therapies that address symptoms rather than underlying pathology, long-term immunosuppressant burden, and waning therapeutic effectiveness over time.

The November 2026 PDUFA date will serve as the first measurable outcome for cemdisiran's regulatory trajectory across all three markets.

Source: Regeneron Pharmaceuticals via GlobeNewswire, 22 June 2026.