Phase 3 NIMBLE Trial: Cemdisiran Efficacy and Safety Results in gMG

As new therapeutic approaches emerge for generalized myasthenia gravis (gMG), clinical trial outcomes must demonstrate more than statistical significance to establish their potential relevance to patient care. Improvements in the Myasthenia Gravis Activities of Daily Living (MG-ADL) scale provide an important measure of treatment benefit, particularly when changes reflect meaningful reductions in disease-related limitations. At the same time, the safety of complement-targeted therapies remains a central consideration, given the potential for increased susceptibility to serious infections.

In this NeurologyLive® Special Report, Ali Habib, MD, a neuromuscular specialist at UCI Health, provides insights into the phase 3 NIMBLE trial (NCT05070858), which evaluated the investigational small interfering RNA therapeutic cemdisiran in adults with gMG. Speaking with NeurologyLive during the 2026 AANEM Annual Meeting, held September 29 to October 2 in Orlando, Florida, Habib discussed the trial's efficacy and safety findings, including a 2.3-point placebo-adjusted improvement in MG-ADL scores at week 24. The conversation also comes alongside exploratory analyses presented at the meeting examining whether treatment with cemdisiran could reduce hospitalizations and other acute complications associated with gMG.

In this episode, Habib provides a clinical interpretation of NIMBLE's efficacy and safety findings, focusing on the magnitude of MG-ADL improvement and its potential relevance to patients' everyday functioning. He also discusses the overall tolerability profile observed during the double-blind treatment period, the incidence of infections, and the importance of meningococcal vaccination when evaluating therapies that inhibit complement activity.

Transcript edited for clarity.

Ali Habib, MD: So, in terms of the results from the NIMBLE study, let's talk about the efficacy outcomes.

Again, the primary outcome measure was the change from baseline in the MG-ADL score at week 24. When we look at the treatment response in the cemdisiran versus placebo group, there was a greater response in the cemdisiran group compared with placebo, with a placebo-adjusted difference of 2.3 points in the cemdisiran group as a change from baseline.

As folks will know, this is a statistically significant difference, but also, as we refer to it, a clinically meaningful change of greater than 2 points, meaning that patients would actually notice an improvement in their myasthenia gravis disease symptom burden with this therapy.

Efficacy is great. Alongside efficacy, what we really want is safety and tolerability. In general, cemdisiran was very well tolerated, with most of the side effects and adverse events noted in the study being mild to moderate.

Importantly, none of those led to discontinuation of cemdisiran therapy. The most common side effect was infections, and this was similar in terms of the proportion of patients experiencing them during the double-blind period compared with the placebo arm.

With cemdisiran blocking complement activity, one of the biggest concerns is that of meningococcal infection. In the trial, patients were required to get vaccinated prior to the start of therapy.

During the double-blind period, there were no incidences of meningococcal infection. So, from the safety standpoint, that's an important point of observation in the trial as well.