Efgartigimod Alfa

**Semantic type:** Pharmacologic Substance

**Definition:** A human immunoglobulin G1 (IgG1)-derived Fc fragment that targets the neonatal Fc receptor (FcRn), with potential FcRn blocking activity. Upon administration, efgartigimod alfa targets, binds to and blocks FcRn, thereby preventing FcRn from recycling IgG back into the systemic circulation. This causes a reduction in IgG blood levels, including the abnormal acetylcholine receptor (AChR) antibodies that are present in myasthenia gravis. FcRn binds to IgGs and prevents their lysosomal degradation, thereby extending IgG half-life and increases the availability of pathogenic IgG antibodies that are present in certain severe autoimmune diseases.

**Synonyms:** - ARGX 113 - ARGX-113 - ARGX113 - EFGARTIGIMOD ALFA - Efgartigimod Alfa-fcab - Vyvgart