Efgartigimod Being Considered as Generalized MG Therapy for Europe
The European Medicines Agency (EMA) has agreed to review Argenx’s application requesting the approval of its lead candidate, efgartigimod (ARGX-113), to treat people with generalized myasthenia gravis (gMG).
A regulatory decision is expected by mid-2022.
“gMG is a severe, chronic and debilitating disease that can be unpredictable and greatly impact a person’s quality of life,” Tim Van Hauwermeiren, Argenx’s CEO, said in a press release.
“The EMA’s validation is an exciting step closer to our goal of helping people globally who are living with this disease in which there remains a significant unmet need,” Van Hauwermeiren added. “We … look forward to our continued collaboration with European regulatory authorities through the review process.”
Should the European Commission approve efgartigimod, health authorities in each European Union member state will decide whether to add the therapy to their respective public health programs, in which patients can access the treatment at low or no cost.
Similar approval requests are currently being reviewed by regulatory agencies in Japan and in the U.S., where a decision is expected no later than Dec. 17.
In people with myasthenia gravis (MG), the immune system wrongly attacks proteins essential for nerve-muscle cell communication by producing immunoglobulin G (IgG) autoantibodies.
Efgartigimod is a lab-made antibody fragment designed to address the underlying cause of MG by preventing the interaction between a receptor protein called FcRn and IgG antibodies, including those driving the onset of MG.
Given that FcRn-IgG binding prevents IgG breakdown and prolongs the time these antibodies remain in the bloodstream, efgartigimod is expected to lower the levels of both total IgG and disease-associated IgG autoantibodies, ultimately easing MG severity.
The therapy was designated an orphan drug in both the U.S. and Europe. This status is meant to speed its development and review, while ensuring a marketing exclusivity period of seven years in the U.S., and 10 years in Europe upon regulatory approval.
According to Argenx, if the therapy is approved by any of these regulatory agencies, it will become the first and only FcRn blocker available in these regions.
Regulatory applications are supported by data from the Phase 3 ADAPT clinical trial (NCT03669588), which evaluated efgartigimod’s safety and effectiveness in 167 adults with gMG, who were recruited at sites across North America, Europe and Japan.
Notably, 129 of these patients were positive for antibodies against acetylcholine receptor (AChR), which are the most common cause of gMG.
Participants were randomly assigned to receive either efgartigimod (10 mg/kg) or a placebo, infused directly into the bloodstream, for 26 weeks (about six months), in addition to their current standard treatments.
Results showed that significantly more AChR-positive patients treated with efgartigimod showed clinically meaningful improvements in the Myasthenia Gravis Activities of Daily Living score, a measure of MG symptom severity, than those on a placebo (67.7% vs. 29.7%), meeting the trial’s main goal.
The therapy was also associated with fast, deep, and durable responses among this subset of patients. Further analyses also showed that efgartigimod was superior to placebo among AChR-negative patients.
The therapy was generally well-tolerated, with a safety profile comparable with that of placebo.
After completing ADAPT, most participants (90%) entered in an open-label extension study, called ADAPT+ (NCT03770403), in which all will receive the therapy for up to three years. This trial is expected to conclude by June 2023.
“There remains a significant unmet need for new gMG treatment options that are targeted to the underlying [mechanisms] of the disease and supported by clinical data,” said Andreas Meisel, MD, one of ADAPT’s principal investigators.
“I am hopeful for continued research advancements for new options to treat this debilitating disease,” added Meisel, who is a senior physician of neurology and head of the MG outpatient clinic with the department of neurology at Charité–Universitätsmedizin Berlin.
In March, Argenx also launched an early access program in the U.S., allowing eligible gMG patients to receive the experimental therapy prior to a regulatory decision in the country. More information on the program is available here.