Under-the-skin efgartigimod now approved in China to treat gMG
Subcutaneous therapy wins regulatory OK as add-on treatment for adults
An under-the-skin, or subcutaneous, injectable form of efgartigimod alfa has been approved in China to treat adults with generalized myasthenia gravis (gMG) who test positive for antibodies against the acetylcholine receptor. The therapy was approved as an add-on to standard gMG treatment.
This subcutaneous formulation of efgartigimod (efgartigimod SC) will be commercialized in China by Zai Lab as part of an exclusive license agreement with the therapy’s developer Argenx. This formulation already is approved in several other countries and regions across the globe, including in the U.S., where it’s marketed as Vyvgart Hytrulo, in Japan, where it’s sold as Vyvdura, and in the European Union, where it’s marketed as Vyvgart SC.
The approval of the biologics license application by China’s National Medical Products Administration follows an approval last year of the intravenous, or into-the-vein, formulation of efgartigimod. That therapy is marketed as Vyvgart.
Rafael G. Amado, MD, president, and head of global research and development at Zai Lab, said in a press release that the approval of efgartigimod SC marks “an important milestone as we bring another first-in-class option to gMG patients in China.”
“The addition of a new treatment option for gMG patients enhances flexibility for patients, potentially further simplifying the regimen and making therapy more accessible within the community,” Amado said.
Efgartigimod SC approval gives patient in China a new treatment option
Myasthenia gravis, or MG for short, is an autoimmune disease characterized by self-reactive antibodies that disrupt nerve-muscle communication. For most patients with gMG, these antibodies attack and damage acetylcholine receptors, a protein found on the surface of muscle cells, leading to symptoms such as increasing muscle weakness and fatigue.
According to Zai Lab, about 170,000 people in China are living with gMG, and of these, approximately 85% have antibodies against the acetylcholine receptor.
Efgartigimod works by blocking the neonatal Fc receptor, thereby promoting the degradation of antibodies circulating in the bloodstream — including MG-causing self-reactive antibodies.
The now-approved formulation is to be administered subcutaneously as a single injection (1,000 milligrams fixed dose) over a timeframe of approximately 30-90 seconds, in an initial regimen of once per week, for four weeks.
“The addition of a flexible 30-to-90 second subcutaneous injection opens the door for new patients in China, while taking into account personal preference and convenience,” said Tim Van Hauwermeiren, CEO of Argenx.
In contrast, current treatments with intravenous Vyvgart typically require an hourlong infusion.
Compared to fixed infusion schedules, the availability of efgartigimod SC allows a more individualized and flexible treatment approach based on patient needs without sacrificing clinical benefit or safety.
Intravenous Vygart was approved in China based on findings from the Phase 3 ADAPT trial (NCT03669588). The therapy was found to be generally safe and tolerable, and to be able to reduce gMG disease severity.
Approval for efgartigimod SC was supported by more recent findings from the Phase 3 ADAPT-SC trial (NCT04735432), which compared four weeks of weekly treatment with either efgartigimod SC (1,000 mg) or Vyvgart (10 mg/kg). That trial involved 110 adults with gMG.
Trial data showed that efgartigimod SC was not inferior to Vyvgart in terms of efficacy. The mean total antibody levels were similarly lowered in both groups at day 29 after treatment compared with when treatment was started. Specifically, a reduction of 66.4% was seen with efgartigimod SC compared with a 62.2% drop with Vyvgart.
The most common adverse event reported with efgartigimod SC was injection site reactions, but these were considered to be mild to moderate and resolved over time. Overall, efgartigimod SC was found to be generally well tolerated.
“In the global Phase 3 ADAPT-SC study, efgartigimod SC demonstrated consistent benefit and safety compared to the intravenous product. This is a meaningful advancement for the patient community,” said Xueqiang Hu, MD, PhD, chief physician of the department of neurology at the Third Affiliated Hospital of Sun Yat-sen University.
“Compared to fixed infusion schedules, the availability of efgartigimod SC allows a more individualized and flexible treatment approach based on patient needs without sacrificing clinical benefit or safety,” Hu added.
Efgartigimod SC also is being investigated as a treatment for other autoimmune conditions. Zai Lab’s exclusive license agreement with Argenx, which dates back to 2021, also gives the company the rights to develop and commercialize efgartigimod in Hong Kong, Macau, and Taiwan.
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