FcRn inhibitors in immune thrombocytopenia: A comprehensive review of therapeutic advances and clinical outcomes

Abstract

Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by low platelet counts, leading to bleeding risks. Despite existing treatments, many patients with chronic or refractory ITP remain inadequately managed. Fc-receptors, including neonatal Fc receptor (FcRn), play a crucial role in the ITP pathogenesis by activating antibody-dependent cell-mediated cytotoxicity and antibody-dependent cell-mediated phagocytosis, leading to platelet destruction. In addition, recent insights highlight cytokine dysregulation, particularly involving interleukin (IL)-17, IL-6, and Interferon-gamma (IFN-γ), as contributing to disease persistence and immune dysfunction. We sought to evaluate the efficacy and safety of FcRn inhibitors for chronic or persistent ITP treatment. PubMed/Medline, Scopus, and Web of Science databases were systematically searched until January 16th, 2025. Preclinical and clinical studies with available full-text in English were included. Efgartigimod significantly improved platelet counts and reduced Immunoglobulin G (IgG) levels in refractory as well as chronic patients with minimal adverse effects. Rozanolixizumab also showed favorable outcomes in terms of platelet count elevation and IgG reduction in Phase 2 and Phase 3 clinical trials in cases who were unresponsive to ≥2 standard-of-care ITP treatments. These immunotherapeutic agents can effectively increase platelet counts and reduce IgG serum levels, addressing a critical need in patients who do not respond to corticosteroids, thrombopoietin receptor agonists (TPO-RAs), and rituximab. Further long-term studies are warranted to confirm these findings and explore their broader clinical implications.

Keywords: Efgartigimod; FcRn; FcRn-inhibitor; ITP; Immune thrombocytopenia; Rozanolixizumab.