argenx announced that the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) has recommended European Commission (EC) approval of efgartigimod 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. The positive CHMP opinion is a scientific recommendation for marketing authorization, serving as a basis for the EC's final decision on argenx's application for efgartigimod. The EC is expected to make a decision within approximately 60 days following CHMP recommendation, which will be applicable to all 27 European Union Member States, in addition to Iceland, Norway and Liechtenstein.

The MAA included results from the pivotal Phase 3 ADAPT trial, which were published in the July 2021 issue of The Lancet Neurology. The ADAPT trial met its primary endpoint, demonstrating that significantly more anti-acetylcholine receptor (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 (68% vs. 30%; p<0.0001).

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 additionally significantly more responders on the Quantitative Myasthenia Gravis (QMG) scale following treatment with efgartigimod compared with placebo (63% vs. 14%; p<0.0001).

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. Efgartigimod had a demonstrated safety profile in the ADAPT clinical trial. The most frequently reported adverse reactions were upper respiratory tract infections (10.7% following treatment with efgartigimod vs.

4.8% of placebo) and urinary tract infections (9.5% vs. 4.8%). The Phase 3 ADAPT trial was a 26-week randomized, double-blind, placebo-controlled, multi-center, global trial evaluating the safety and efficacy of efgartigimod in adult patients with gMG.

A total of 167 adult patients with gMG in North America, Europe and Japan enrolled in the trial. Patients were randomized in a 1:1 ratio to receive efgartigimod or placebo, in addition to stable doses of their current gMG treatment. ADAPT was designed to enable an individualized treatment approach with an initial treatment cycle followed by subsequent treatment cycles based on clinical evaluation.

The primary endpoint was the comparison of percentage of MG-ADL responders in the first treatment cycle between efgartigimod and placebo treatment groups in the anti-AChR antibody positive population.