Cemdisiran Achieves Breakthrough Results in Phase 3 Myasthenia Gravis Trial, Positioning for First siRNA Approval
核心洞察
Regeneron's investigational siRNA therapeutic cemdisiran demonstrated superior efficacy over placebo in the Phase 3 NIMBLE trial for generalized myasthenia gravis (搜索), meeting both primary and key secondary endpoints with a 2.3-point improvement in daily living activities (p<0.001).
The therapy showed rapid onset of action within two weeks and sustained benefits through 24 weeks with convenient quarterly dosing, potentially offering best-in-class efficacy compared to approved C5 (搜索) inhibitors.
Cemdisiran exhibited a favorable safety profile with lower infection rates than placebo and could become the first siRNA therapy approved for myasthenia gravis (搜索) treatment following U.S. regulatory submission in Q1 2026.
Regeneron Pharmaceuticals announced positive results from the Phase 3 NIMBLE trial of cemdisiran, an investigational siRNA therapeutic targeting complement factor 5 (搜索) (C5 (搜索)), for the treatment of generalized myasthenia gravis (搜索) (gMG). The results, published in The Lancet and presented at the American Academy of Neurology Annual Meeting, demonstrated the therapy's potential to become the first siRNA approved for this debilitating autoimmune condition.
Trial Results Demonstrate Superior Efficacy
The randomized, double-blind, placebo-controlled NIMBLE trial, described as the largest global interventional gMG study to date, enrolled patients with anti-acetylcholine receptor (搜索) antibodies who could continue background immunosuppressants. Patients receiving subcutaneous cemdisiran (600 mg) every 12 weeks (n=64) showed significant improvements compared to placebo (n=59) across multiple measures.
At week 24, cemdisiran achieved a 4.5-point improvement from baseline on the Myasthenia Gravis (搜索)-Activities of Daily Living (MG-ADL) total score compared to a 2.2-point improvement with placebo. This resulted in a placebo-adjusted improvement of 2.3 points (p<0.001), meeting the primary endpoint. Notably, 76.6% of cemdisiran patients experienced a ≥3-point improvement versus 44.1% for placebo.
The therapy also met its key secondary endpoint, demonstrating a 4.2-point improvement from baseline in Quantitative Myasthenia Gravis (搜索) (QMG) total score compared to 1.5 points with placebo, resulting in a placebo-adjusted improvement of 2.8 points (p=0.002). Nearly half (48.4%) of cemdisiran patients achieved a ≥5-point improvement compared to 19% receiving placebo.
Rapid Onset and Sustained Benefits
"In the Phase 3 NIMBLE trial, this first-of-its-kind investigational therapy demonstrated rapid, robust efficacy with lasting benefit through 24 weeks," said Dr. Tuan Vu, Professor of Neurology at the University of South Florida Morsani College of Medicine and global principal investigator of the NIMBLE trial. "These impressive results suggest cemdisiran can represent a transformative advance in care for people living with gMG, offering compelling efficacy coupled with convenient four-times-a-year subcutaneous administration."
Clinically meaningful improvements occurred within two weeks of treatment initiation, with cemdisiran-treated patients showing a -2.5-point change from baseline in MG-ADL scores and a -1.9-point change in QMG scores. These improvements deepened over time and were sustained through week 24 with no indication of waning efficacy between doses.
Competitive Efficacy Profile
The trial results position cemdisiran favorably against approved C5 (搜索) inhibitor therapies. According to the data, approved C5 inhibitors have demonstrated 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 in previous registrational trials, typically measured at week 12 or 26.
Favorable Safety Profile
Treatment-emergent adverse events occurred in 69.2% of cemdisiran patients compared to 77.1% receiving placebo, with most events being mild-to-moderate in severity. The most common adverse events (≥5%) in cemdisiran patients included upper respiratory tract infection (12%), urinary tract infection (5%), nasopharyngitis (5%), headache (5%), and rash (5%).
Importantly, infection rates during the double-blind treatment period were lower with cemdisiran (27%) compared to placebo (40%). No serious infections, meningococcal infections, or deaths occurred during the treatment period. Treatment discontinuations due to adverse events were absent in the cemdisiran arm through week 24, compared to 3% with placebo.
Disease Background and Unmet Need
Myasthenia gravis (搜索) affects approximately 85,000 people in the United States. The autoimmune condition involves abnormal acetylcholine receptor (搜索) antibodies that activate the complement system, including C5 (搜索), disrupting nerve-muscle communication and causing debilitating muscle weakness. While initial symptoms are typically ocular, approximately 85% of patients progress to generalized disease affecting muscles throughout the body, resulting in extreme fatigue and difficulties with facial expression, speech, swallowing, and mobility.
"Generalized myasthenia gravis (搜索) is a chronic debilitating disease with unpredictable symptoms that impact daily life. While current therapies have managed disease activity, there remains an unmet need for options that achieve rapid and sustained efficacy with reduced treatment burden," Dr. Vu noted.
Regulatory Pathway and Development Program
Regeneron submitted the U.S. regulatory application for cemdisiran in the first quarter of 2026, with additional regulatory filings planned for the European Union later in 2026. If approved, cemdisiran would become the first siRNA therapeutic for gMG treatment.
The NIMBLE trial evaluated four subcutaneous regimens: cemdisiran (600 mg) every 12 weeks, a combination of cemdisiran (200 mg) and pozelimab (200 mg) every 4 weeks, pozelimab (200 mg) every 4 weeks, or placebo every 4 weeks. Cemdisiran and pozelimab are also being evaluated in separate Phase 3 trials for additional complement-mediated disorders, including paroxysmal nocturnal hemoglobinuria and geographic atrophy secondary to age-related macular degeneration.
Regeneron holds worldwide licensing rights for cemdisiran development, manufacturing, and commercialization through an agreement with Alnylam. The company plans to host a virtual investor event on April 22, 2026, to discuss its C5 (搜索) development program as part of its "Regeneron Roundtable" series.