Regeneron Reports Phase 3 Success for Cemdisiran in Rare Disease Generalized Myasthenia Gravis

Regeneron announced positive Phase 3 results for cemdisiran, an investigational RNA (siRNA) drug for generalized myasthenia gravis (gMG), a rare autoimmune disease13.

The Phase 3 NIMBLE trial met both its primary and key secondary endpoints, with cemdisiran monotherapy producing a 2.3-point placebo-adjusted improvement in disease symptom scores and an average 74% inhibition of complement activity1.

Cemdisiran was also tested in combination with the C5 antibody pozelimab ('cemdi-poze'), but the monotherapy was numerically superior on key endpoints3.

No patients in the cemdisiran monotherapy group discontinued treatment due to side effects through week 24. Serious treatment-related adverse events were lower in the cemdisiran group (3%) versus the combination (9%) or placebo (14%)3.

The most common side effects were upper respiratory tract infection, urinary tract infection, common cold, and headache3.

No meningococcal infections occurred in study participants3.

A U.S. regulatory submission for cemdisiran in gMG is planned for the first quarter of 202613.

Sources:

1. https://www.globenewswire.com/news-release/2025/08/26/3139144/0/en/Regeneron-Announces-Positive-Results-from-Phase-3-Trial-in-Generalized-Myasthenia-Gravis.html

3. https://www.biopharmadive.com/news/regeneron-myasthenia-gravis-cemdisiran-alnylam-study-results/758607/