Safety profile of efgartigimod from global clinical trials across multiple immunoglobulin G-mediated autoimmune diseases

Background: Efgartigimod is approved in multiple regions for the treatment of gMG, ITP, and CIDP, and is being evaluated in multiple IgG-mediated autoimmune diseases. Here, we report the long-term safety profiles of efgartigimod IV and PH20 SC across different dosing regimens and diseases where efgartigimod has received regulatory approval. Research design and methods: Efgartigimod safety was assessed across dosing regimens and administration routes in Phase 2, placebo-controlled Phase 3, and OLE studies in participants with gMG, ITP, and CIDP. Analyses were performed on all participants who received ≥ 1 dose or partial dose of efgartigimod or placebo. Data from efgartigimod-treated participants were pooled per disease. Event rates were calculated as events per PYFU. Results: Pooled data included 715 participants representing > 850 PYFU. In efgartigimod-treated participants, most TEAEs were mild-to-moderate in severity, with consistently low event rates for TEAE-related treatment discontinuation (range: 0.05–0.47). Severe and serious infection rates were comparable between placebo- and efgartigimod-treated participants. Rates of TEAEs, severe and serious infections, and treatment discontinuation did not increase with prolonged efgartigimod exposure. Efgartigimod did not reduce albumin or increase LDL cholesterol levels. Conclusions: Across clinical trials in IgG-mediated autoimmune diseases, efgartigimod was well tolerated with similar safety profiles regardless of dosing regimen.