Efgartigimod IV Beneficial in AChR-Ab Seronegative Generalized Myasthenia Gravis

Topline results were announced from a phase 3 trial evaluating efgartigimod alfa-fcab in patients with acetylcholine receptor binding antibody (AChR-Ab) seronegative generalized myasthenia gravis (gMG).

The intravenous (IV) formulation of efgartigimod, a neonatal Fc receptor blocker, is currently approved under the brand name Vyvgart^® for the treatment of gMG in adult patients who are anti-acetylcholine receptor antibody positive. 

In Part A of the ADAPT SERON trial (ClinicalTrials.gov Identifier: NCT06298552), study participants with AChR-Ab seronegative gMG (MuSK-Ab seropositive, LRP4-Ab seropositive, or triple seronegative) were randomly assigned to receive 4 once-weekly infusions of efgartigimod IV or placebo. 

The primary endpoint was the Myasthenia Gravis Activities of Daily Living (MG-ADL) total score change from baseline to day 29. To be included in the trial, patients had to have an MG-ADL total score of at least 5 at baseline.

Findings showed treatment with efgartigimod IV was associated with a statistically significant and clinically meaningful improvement in MG-ADL total score compared with placebo (P =.0068). No new adverse events were observed in the trial. The safety profile of efgartigimod in patients with AChR-Ab seronegative gMG was found to be consistent with the one observed in patients with AChR-Ab seropositive gMG.

“The results of the ADAPT SERON study, the largest study to date of AChR-Ab seronegative gMG, confirm that Vyvgart now has the potential to be a targeted, effective, safe, and necessary treatment for patients living with gMG, regardless of autoantibody status,” said James F. Howard Jr, MD, Professor of Neurology (Neuromuscular Disease), Medicine and Allied Health, Department of Neurology, The University of North Carolina at Chapel Hill School of Medicine and principal investigator for the ADAPT SERON trial.

Full results from the ADAPT SERON trial will be presented at a future medical meeting. According to argenx, the study will be used to support an expanded label for Vyvgart to include treatment of AChR-Ab seronegative gMG patients. The supplemental Biologics License Application is expected to be submitted to the Food and Drug Administration by the end of 2025.

This article originally appeared on MPR