Neonatal Fc Receptor Inhibitor Therapeutics in Neuromuscular Disease

The Neonatal Fc Receptor (FcRn) is integral to a wide variety of processes including IgG recycling, serum albumin turnover, and bacterial opsonization. Thus, targeting FcRn will increase antibody degradation including pathogenic IgGs. FcRn inhibition provides a novel therapeutic mechanism by which autoantibody titers are reduced resulting in clinical improvement and disease abatement. The FcRn targeting mechanism is similar to that of intravenous immunoglobulin (IVIg) in which saturated FcRn facilitates accelerated pathogenic IgG degradation. Recently, the FcRn inhibitor efgartigimod was approved for the treatment of myasthenia gravis. Subsequently, clinical trials of this agent have been conducted for numerous inflammatory conditions involving pathogenic autoantibodies. These disorders include the Guillain-Barre syndrome, chronic inflammatory demyelinating polyneuropathy, and inflammatory myositis. Other disorders traditionally treated with IVIg may also benefit from FcRn inhibition in certain contexts. This manuscript discusses the mechanism of FcRn inhibition, preclinical data, and the results of clinical trials of this agent for a wide range of neuromuscular diseases.