New horizons for autoimmune hyperthyroidism with FcRn blockers.

PURPOSE OF REVIEW: Advances in understanding of autoimmune hyperthyroidism and neonatal Fc receptor (FcRn) biology have created an opportunity for a novel immunomodulatory treatment approach. This review is timely in evaluating newly emerged literature for FcRn blockers Batoclimab (IMVT-1401), Imeroprubart (IMVT-1402) and Efgartigimod (ARGX-113) in Graves' disease and thyroid eye disease. RECENT FINDINGS: Preliminary phase 2 clinical trial data of Batoclimab therapy in Graves' disease demonstrated rapid normalisation of thyroid hormone levels with the majority maintaining this after the treatment course. Rapid declines in anti-TSH receptor antibodies were observed with a subset of patients achieving sustained seroconversion. A case report described maintained remission of Graves' disease 23 months following short-course Batoclimab therapy. Batoclimab was well tolerated with no treatment-related adverse events. Phase 3 clinical trials of Efgartigimod therapy in thyroid eye disease were terminated early due to it unlikely achieving the intended clinical efficacy following interim analysis. Mid- and late-phase clinical trials for Imeroprubart and Batoclimab therapy in Graves' disease and thyroid eye disease are ongoing. SUMMARY: FcRn blockade is a promising new therapeutic approach for the management of autoimmune hyperthyroidism. Durability, cost-effectiveness and patient selection remain to be defined.