First FcRn blocker approved in UK for myasthenia gravis

The Medicines and Healthcare products Regulatory Agency (MHRA) has granted marketing authorisation for VYVGART^® (efgartigimod alfa-fcab). It is the first neonatal Fc receptor (FcRn) blocker to be approved in the UK for adults with generalised myasthenia gravis (gMG) who are anti-acetylcholine receptor (AChR) antibody positive.

VYVGART is a human IgG1 antibody fragment that binds to the neonatal Fc receptor (FcRn). It reduces the reduction of circulating immunoglobulin G (IgG) autoantibodies. In gMG, an autoimmune disease, IgG autoantibodies disrupt communication between nerves and muscles and cause significant and potentially life-threatening muscle weakness.

Approved as an add-on to standard therapy, VYVGART offers “patients a new treatment option that is targeted to the underlying pathogenesis of the disease and supported by strong efficacy, safety and tolerability data,” stated Professor Saiju Jacob, Consultant Neurologist at the University Hospitals Birmingham.        

About the Phase III ADAPT Trial

The MHRA approval is based on results from the global Phase III ADAPT trial.

The clinical trial evaluated the safety and efficacy of efgartigimod in 167 patients. It demonstrated that 68 percent of 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 30 percent of placebo 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 (63 percent versus 14 percent; 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.

ADAPT was designed to enable an individualised treatment approach with an initial treatment cycle followed by subsequent treatment cycles. 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.

Previous positive regulatory opinions for the neonatal Fc receptor blocker

The antibody fragment VYVGART was granted a Promising Innovative Medicine (PIM) designation by the MHRA in November 2021, as well as a positive scientific opinion under the Early Access to Medicines Scheme in May 2022.