Cemdisiran for Generalized myasthenia gravis (anti-AChR antibody-positive adults)
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The FDA is expected to decide on Cemdisiran for Generalized myasthenia gravis (anti-AChR antibody-positive adults) in November 2026, under an 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
Read our full Myasthenia Gravis treatment summary
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.
The Myasthenia Gravis page has every treatment and trial →Meanwhile, 122 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:
Earlier-stage drugs Trial Friend tracks for Myasthenia Gravis
We'll email you when the decision is public, with what it means in plain language, and when new trials open for Myasthenia Gravis. Unsubscribe anytime.
Our coverage
Frequently asked questions
When will the FDA decide on Cemdisiran?
Regeneron expects a decision in November 2026 but has not given an exact date.
Who disclosed it: Regeneron. The FDA does not publish these dates.
Can it move: the FDA can act early, and a major amendment to the application can push the date back 3 months.
Source: Regeneron press release
What is Cemdisiran being reviewed for?
Regeneron submitted an NDA for Cemdisiran in Generalized myasthenia gravis (anti-AChR antibody-positive adults).
What to know: 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.
Is there already an FDA-approved treatment for Myasthenia Gravis?
Yes. Trial Friend's drug list includes 7 FDA-approved drugs for Myasthenia Gravis.
Approved: Soliris (eculizumab), Vyvgart (efgartigimod alfa), Ultomiris (ravulizumab), Rystiggo (rozanolixizumab), Zilbrysq (zilucoplan), Uplizna (inebilizumab), Imaavy (nipocalimab).
Check: the Myasthenia Gravis page also searches FDA drug labels for approved treatments.
Can I get Cemdisiran before the FDA decides?
Usually only through a clinical trial or an expanded access program, and the company decides whether to offer one.
Trials: 122 Myasthenia Gravis trials are recruiting now. See them.
Check your fit: Match Me compares your details with every open trial.
Expanded access: your doctor can ask Regeneron directly. Registered programs are listed on ClinicalTrials.gov.
How much will Cemdisiran cost?
Regeneron has not announced a price. Drugmakers usually set it around approval.
Help paying: drugmaker programs and charity funds usually open at launch.
Find help: the patient assistance finder lists programs by insurance type.
What happens after the Cemdisiran decision?
This page updates with the outcome the day it is announced.
If approved: getting the drug still takes time. Specialty pharmacy setup, insurance review and patient assistance often take weeks. Our guide covers what families can do on day 1.
If not approved: a complete response letter means the FDA declined the application in its current form. Many are about manufacturing or how data were presented, and companies often resubmit.
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.