Regeneron Pharmaceuticals, Inc. ( REGN ) on Tuesday shared data from the Phase 3 NIMBLE trial assessing investigational cemdisiran monotherapy in adults with generalized myasthenia gravis (gMG).

gMG is a rare, chronic autoimmune disease that causes weakness in voluntary muscles, affecting the eyes, face, neck, arms, legs, and breathing.

The trial met the primary and key secondary endpoints.

Cemdisiran is an siRNA that reduces circulating levels of complement factor 5 (C5) and, as monotherapy in this trial, was associated with an average of 74% inhibition of complement activity.

Cemdisiran’s Breakthrough: A Game Changer For GMG

The trial also assessed a combination of cemdisiran and pozelimab, a C5 antibody. The combination (cemdi-poze), which resulted in nearly 99% inhibition of complement activity, also met the primary and key secondary endpoints, though cemdisiran monotherapy was numerically better across these endpoints.

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Patients were randomized to receive subcutaneous administrations of: cemdisiran (600 mg) every 12 weeks, cemdi-poze (cemdisiran 200 mg and pozelimab 200 mg) every 4 weeks, or placebo every 4 weeks.

The primary endpoint assessed total score changes from baseline to week 24 in the Myasthenia Gravis Activities of Daily Living (MG-ADL) total score, a patient-reported questionnaire that measures daily functions impacted by gMG, such as talking, eating, breathing, vision, and mobility.

The key secondary endpoint assessed total score changes from baseline in the Quantitative Myasthenia Gravis (QMG) total score, a physician-administered assessment evaluating vision, speaking/swallowing, breathing, and limb function.

Historical clinical trial data report that currently approved C5 inhibitor therapies have shown a placebo-adjusted treatment difference in MG-ADL total scores ranging from ­-1.6 to -2.1 at 12 to 26 weeks.

Both cemdisiran and cemdi-poze demonstrated improvements in activities of daily functioning at week 24, with cemdisiran showing numerically better results across all gMG-specific outcomes.

How Does Cemdi-Poze Compare To Monotherapy?

In the MG-ADL and QMG, greater reductions in total scores indicate greater improvement in disease symptoms and better treatment effect.

There were no meningococcal infections in any patient. There were no treatment discontinuations due to adverse events through week 24 in the cemdisiran arm.

Detailed results from the NIMBLE trial will be presented at an upcoming medical meeting.

The U.S. regulatory application for cemdisiran is planned for the first quarter of 2026, pending discussions with the FDA.

Key Metrics Reveal Cemdisiran’s Efficacy Edge

In July, AstraZeneca Plc ( AZN ) reported high-level results from the PREVAIL Phase 3 trial evaluating the safety and efficacy of gefurulimab in adults with gMG. The trial enrolled 260 patients.

Data demonstrated a statistically significant and clinically meaningful improvement from baseline in the MG-ADL total score at week 26 compared to placebo.

Argenx SE ( ARGX ) released topline data from the pivotal Phase 3 ADAPT SERON study of Vyvgart (IV: efgartigimod alfa-fcab) on Monday.

The study met its primary endpoint, demonstrating that AChR-Ab seronegative gMG patients treated with Vyvgart achieved a statistically significant and clinically meaningful improvement in MG-ADL total score compared to placebo.

REGN Price Action: Regeneron Pharmaceuticals ( REGN ) shares were up 1.83% at $582.83 at the time of publication on Tuesday, according to Benzinga Pro data.

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