全身型重症筋無力症の新しい治療薬エフガルチギモド皮下注製剤

Subcutaneous Injection of Efgartigimod, a New Therapeutic Agent for Generalized Myasthenia Gravis

胎児性Fc受容体阻害薬であるエフガルチギモドアルファ・ボルヒアルロニダーゼアルファ配合皮下注製剤（エフガルチギモド皮下注製剤）は，全身型重症筋無力症（generalized myasthenia gravis：gMG）治療薬として2024年1月に本邦で承認され，4月に発売された。皮下投与後に，ボルヒアルロニダーゼアルファの作用によってエフガルチギモドアルファの体内への拡散および吸収が促進される。自己注射が可能な製剤であるため，gMG患者の利便性向上や医療従事者の負担軽減が期待される。

Abstract

Patients with generalized myasthenia gravis (gMG) suffer from significant physical and social burdens. Although immunotherapies have been widely used for the treatment of gMG, some patients do not achieve or maintain remission. Recently, several molecular-targeting therapies of gMG, including the intravenous infusion of efgartigimod alfa (efgartigimod IV), a neonatal Fc receptor inhibitor, have been developed and are clinically used in Japan. In 2024, combination subcutaneous injection of efgartigimod alfa and vorhyaluronidase alfa (efgartigimod SC) was approved for the treatment of patients with gMG (only when treatment with steroids or non-steroidal immunotherapies does not lead to sufficient response). Efgartigimod SC contains vorhyaluronidase alfa, which temporarily and locally facilitates diffusion of efgartigimod alfa, resulting in its absorption enhancement. An international phase III, ADAPT-SC study in patients with gMG, including Japanese demonstrates the non-inferiority of efgartigimod SC to efgartigimod IV in reduction of total IgG by 4 weeks treatment. An extension ADAPT-SC+ study demonstrates the long-term safety and tolerability as well as repeatable clinical benefit across multiple efgartigimod SC treatment cycles. As a self-injectable drug, efgartigimod SC may not only contribute to satisfy unmet medical needs in gMG therapy, but also improve convenience for patients and healthcare providers.

(Received July 11, 2024; Accepted September 13, 2024; Published January 1, 2025)