Regeneron announces publication of Phase 3 NIMBLE trial results

Regeneron (REGN) Pharmaceuticals announced detailed results from the Phase 3 NIMBLE trial evaluating investigational cemdisiran in adults with generalized myasthenia gravis were published in The Lancet and presented for the first time in an oral plenary session at the American Academy of Neurology Annual Meeting. Cemdisiran is a novel siRNA therapeutic that durably reduces circulating levels of complement factor 5, allowing for every three months dosing.The NIMBLE trial results at AAN provide additional detail to the topline data shared in August 2025. As presented, and as compared to placebo, patients treated with subcutaneous cemdisiran every twelve weeks experienced clinically meaningful improvements within two weeks on two assessment scales that measured changes from baseline in: daily functions impacted by gMG and muscle function. These improvements deepened over time across both scales and were sustained through week 24, with no indication of waning efficacy between doses. Specifically, the results for cemdisiran compared to placebo at week 24 demonstrated a: 4.5-point improvement from baseline on the Myasthenia Gravis-Activities of Daily Living total score compared to a 2.2-point improvement. This corresponded to a placebo-adjusted improvement of 2.3 points, meeting the primary endpoint. Notably, 76.6% of cemdisiran patients had a greater than or equal to3-point improvement, versus 44.1% for placebo. Clinically meaningful improvements in MG-ADL total score occurred within 2 weeks in cemdisiran-treated patients, which was a pre-specified exploratory endpoint. MG-ADL is a patient-reported assessment of daily functions impacted by gMG. 4.2-point improvement from baseline in Quantitative Myasthenia Gravis total score compared to a 1.5-point improvement. This resulted in a placebo-adjusted improvement of 2.8 points, meeting the key secondary endpoint. Notably, 48.4% of cemdisiran patients had a greater than or equal to5-point improvement, compared to 19% for placebo. Improvements in QMG total scores occurred within 2 weeks in cemdisiran-treated patients, which was a pre-specified exploratory endpoint. QMG is a physician-administered assessment of muscle function. Approved C5 inhibitor therapies have demonstrated in previous registrational clinical trials placebo-adjusted improvements in MG-ADL total scores ranging from -1.6 to -2.1 and in QMG total scores ranging from -2.0 to -3.0 at the time of each trial’s primary analysis. One or more treatment-emergent adverse events occurred in 69.2% of patients receiving cemdisiran and 77.1% receiving placebo. Most AEs were mild-to-moderate in severity. The most common AEs in patients receiving cemdisiran or placebo were: worsening of MG, upper respiratory tract infection, urinary tract infection, nasopharyngitis, headache, rash, and diarrhea. Overall, the rates of infection during the double-blind treatment period were 27% in the cemdisiran group and 40% in the placebo group. No serious infections, meningococcal infections, or deaths occurred during the DBTP. There were no treatment discontinuations due to adverse events through week 24 in the cemdisiran arm compared to 3% of patients receiving placebo. Adverse events leading to dose interruption/reduction occurred in 1% and 4% of patients receiving cemdisiran and placebo, respectively. During the extension period, one death due to pneumonia occurred in the cemdisiran arm in a patient with a significant co-morbidity and also receiving concomitant immunosuppressive therapy. Rates of hospitalization, myasthenic crisis and rescue therapy were numerically lower with cemdisiran. The potential use of cemdisiran for the treatment of gMG is investigational and has not been approved by any regulatory authority. The U.S. regulatory application for cemdisiran was submitted in the first quarter of 2026; additional regulatory filings, including in the European Union, are planned for 2026.