Immunology company argenx SE (Euronext:ARGX) (Nasdaq:ARGX) announced on Thursday that the European Commission has approved VYVGART (efgartigimod alfa-fcab) as an add-on to standard therapy for the treatment of adult patients with generalized myasthenia gravis (gMG) who are anti-acetylcholine receptor (AChR) antibody positive.

gMG is a rare and chronic autoimmune disease where immunoglobulin G (IgG) autoantibodies disrupt communication between nerves and muscles, causing debilitating and potentially life-threatening muscle weakness. Patients with confirmed AChR antibodies account for approximately 85% of all those with gMG.

This approval was based on results from a Phase 3 trial which demonstrated that significantly more anti-AChR antibody positive gMG patients were responders on the Myasthenia Gravis Activities of Daily Living (MG-ADL) scale following treatment with efgartigimod compared with placebo. Responders were defined as having at least a two-point reduction on the MG-ADL scale sustained for four or more consecutive weeks during the first treatment cycle.

There were also significantly more responders on the Quantitative Myasthenia Gravis (QMG) scale following treatment with efgartigimod compared with placebo. On this measure, responders were defined as having at least a three-point reduction on the QMG scale sustained for four or more consecutive weeks during the first treatment cycle.

The approval is applicable to all 27 European Union Member States plus Iceland, Norway and Liechtenstein.