Cemdisiran for Generalized myasthenia gravis (anti-AChR antibody-positive adults)
The FDA is expected to decide on Cemdisiran for Generalized myasthenia gravis (anti-AChR antibody-positive adults) in November 2026, under a NDA from Regeneron.
What is being decided
Regeneron has an NDA under FDA review for Cemdisiran in Generalized myasthenia gravis (anti-AChR antibody-positive adults). An siRNA that lowers the liver's production of complement protein C5, injected under the skin every 12 weeks. The FDA granted Priority Review with a target action date in November 2026; Regeneron has not disclosed the exact day. In the Phase 3 NIMBLE trial, published in The Lancet, MG-ADL scores improved 2.3 points more than placebo at week 24. If approved, it would join Soliris, its biosimilars, Ultomiris and Zilbrysq as a C5-targeting option for AChR-positive adults.
Who this decision matters to
Myasthenia gravis is a chronic autoimmune neuromuscular disorder causing muscle weakness and rapid fatigue. Antibodies attack acetylcholine receptors at the neuromuscular junction, preventing proper muscle contraction. The condition is manageable with medications and other treatments that suppress the immune response.
Prevalence: 1 in 5,000 people. See our full Myasthenia Gravis page for current treatments, recruiting trials, and community resources.
What each outcome would mean
An approval starts a second race rather than ending the first one: specialty pharmacy setup, insurance review, and patient assistance typically take weeks even when everything goes right. Our guide to the 90 days after a rare disease approval explains the timeline and the moves families can make on day 1.
A complete response letter would mean the FDA declined to approve in the application's current form. CRLs are often about manufacturing or data presentation rather than efficacy, and resubmission is common. Either way, this page updates with the outcome and what it means.
Where Myasthenia Gravis treatment stands today
Myasthenia gravis treatment options are expanding rapidly with new targeted therapies entering clinical trials. FcRn inhibitors reduce pathogenic antibody levels, while complement inhibitors block the destruction of acetylcholine receptors. Another FcRn blocker, nipocalimab (Imaavy), was FDA approved in April 2025 for generalized MG in adults and children 12 and older who are AChR or MuSK antibody positive, and is given by IV infusion every 2 weeks after a first loading dose. Trials are designed for specific antibody subtypes, with the most options available for AChR-positive patients. MuSK-positive patients are increasingly included in FcRn inhibitor and complement studies, while seronegative MG patients have the fewest dedicated trial options. Pyridostigmine (Mestinon) is almost always allowed during trials. If you are on a targeted therapy like Vyvgart or Soliris and want to join a new trial, expect a washout period of 4 weeks to 4 months depending on the drug class. Your MG-ADL score, MGFA classification, and recent flare history all factor into trial eligibility. The Myasthenia Gravis Foundation of America tracks trial opportunities. Your neuromuscular specialist can help determine which emerging therapies match your antibody subtype, disease severity, and current medication regimen.
Meanwhile, 130 Myasthenia Gravis trials are recruiting
Whatever the FDA decides here, research on Myasthenia Gravis does not stop. A few currently enrolling studies, US sites first:
Other drugs Trial Friend tracks for Myasthenia Gravis
Get notified when new myasthenia-gravis trials open or existing trials change status, add sites, or update eligibility.
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Frequently asked questions
When will the FDA decide on Cemdisiran?
Regeneron has disclosed a decision window of November 2026 for Cemdisiran in Generalized myasthenia gravis (anti-AChR antibody-positive adults), without an exact date.
What is Cemdisiran being reviewed for?
Regeneron submitted a NDA for Cemdisiran in Generalized myasthenia gravis (anti-AChR antibody-positive adults). An siRNA that lowers the liver's production of complement protein C5, injected under the skin every 12 weeks. The FDA granted Priority Review with a target action date in November 2026; Regeneron has not disclosed the exact day. In the Phase 3 NIMBLE trial, published in The Lancet, MG-ADL scores improved 2.3 points more than placebo at week 24. If approved, it would join Soliris, its biosimilars, Ultomiris and Zilbrysq as a C5-targeting option for AChR-positive adults.
What happens after the Cemdisiran decision?
If approved, availability is not immediate: specialty pharmacy setup, insurance review, and patient assistance typically take weeks even when everything goes right. If the FDA issues a complete response letter, the application was not approved in its current form; CRLs are often about manufacturing or data presentation rather than efficacy, and sponsors frequently resubmit. This page updates with the outcome either way.
Where this date comes from
The FDA does not publish PDUFA dates; companies disclose them. This one comes from Regeneron press release. Dates can move, and the FDA can act early or late. This page rechecks against our calendar, which is re-verified daily.