Argenx and Zai Lab Announce China Approval of Efgartigimod Alfa for Myasthenia Gravis

On July 16, 2024, argenx SE and Zai Lab Limited announced the approval of their Biologics License Application (BLA) by China’s National Medical Products Administration (NMPA) for efgartigimod alfa injection (efgartigimod SC). This subcutaneous injectable is intended as an additional treatment alongside standard therapy for adult patients with generalized myasthenia gravis (gMG) who are anti-acetylcholine receptor (AChR) antibody positive.

Efgartigimod SC is the first NMPA-approved subcutaneous injectable FcRn blocker for gMG patients in China. The approval marks a significant milestone for argenx and Zai Lab in expanding their reach to new patient populations. Tim Van Hauwermeiren, CEO of argenx, expressed pride in this achievement, emphasizing the partnership with Zai Lab. This collaboration has successfully introduced 2,700 new patients to VYVGART IV treatment in the first quarter of 2024, highlighting the ongoing unmet needs of gMG patients in China.

The introduction of efgartigimod SC offers a flexible and convenient 30-to-90 second subcutaneous injection option, which is expected to appeal to new patients by considering their personal preferences. Van Hauwermeiren looked forward to furthering the partnership with Zai Lab and expanding their presence in China, one of the world's fastest-growing markets, to benefit more individuals with severe autoimmune diseases.

Rafael G. Amado, M.D., President of Global Research and Development at Zai Lab, also expressed satisfaction with the NMPA approval. Dr. Amado highlighted that the new treatment option provides enhanced flexibility for patients, potentially simplifying the treatment regimen and making therapy more accessible within the community. The thorough assessment by NMPA and recognition of the therapy's differentiated profile underscore the significant unmet medical need in China.

Prof. Xueqiang Hu, M.D., Ph.D., Chief Physician of the Neurology Department at the Third Affiliated Hospital of Sun Yat-sen University, emphasized the importance of efgartigimod SC for the gMG patient community. He noted that the subcutaneous option allows for a more individualized treatment approach without compromising clinical benefit or safety. This is backed by the Phase 3 ADAPT-SC study, which demonstrated consistent clinical benefits and safety of efgartigimod SC compared to intravenous administration.

The approval of efgartigimod SC by NMPA is based on positive results from the global Phase 3 ADAPT-SC study. This study bridged to the Phase 3 ADAPT study, which formed the basis for the approval of intravenous VYVGART for adult gMG patients. The ADAPT-SC study met its primary endpoint of noninferiority and showed a mean total IgG reduction of 66.4% from baseline at day 29, compared to 62.2% with intravenous efgartigimod. Additional secondary endpoints were also met, and the safety profile of efgartigimod SC was consistent with the ADAPT study. The most common adverse events were mild to moderate injection site reactions, which resolved over time.

Efgartigimod SC is also being evaluated for treating other autoimmune disorders. In May 2024, the NMPA accepted a supplemental Biologics License Application (sBLA) with priority review for efgartigimod SC in chronic inflammatory demyelinating polyneuropathy (CIDP). In June 2024, the U.S. Food and Drug Administration (FDA) approved efgartigimod SC for adults with CIDP.

VYVGART (efgartigimod alfa injection) is a human IgG1 antibody fragment that binds to the neonatal Fc receptor (FcRn), reducing circulating IgG autoantibodies. It is the first approved FcRn blocker for treating adults with generalized myasthenia gravis (gMG) who are anti-AChR antibody positive. Efgartigimod SC includes recombinant human hyaluronidase PH20 (rHuPH20) to facilitate subcutaneous delivery. The product is administered as a single injection over 30-to-90 seconds in cycles of weekly injections for four weeks. It is approved in the U.S. (marketed as VYVGART® Hytrulo), EU (marketed as VYVGART® SC), and Japan (marketed as VYVDURA®).

Efgartigimod holds potential for treating various severe autoimmune diseases where pathogenic IgGs are implicated and is being evaluated in several autoimmune indications. Zai Lab has an exclusive license agreement with argenx to develop and commercialize efgartigimod in Greater China.

Myasthenia gravis (MG) is a chronic autoimmune disease characterized by muscle weakness, affecting approximately 170,000 people in China. The generalized form of the disease, which involves AChR antibodies, can lead to debilitating and potentially life-threatening symptoms. Current treatments in China, including Acetylcholinesterase (AChE) inhibitors, steroids, immunosuppressants, and IVIg, often provide only partial relief, underscoring the need for new therapeutic options.