Deterioration in multifocal motor neuropathy upon treatment of immune-related adverse events of checkpoint inhibition.

Immune checkpoint inhibitors (ICIs) have significantly improved the clinical outcome in multiple types of advanced or metastatic malignancies and are prescribed increasingly. However, immune-related adverse events (irAEs) occur frequently. Here, we present a patient with multifocal motor neuropathy and melanoma, with worsening of muscle weakness upon ICI therapy and concomitant use of steroids for the treatment of hepatitis, which was considered an irAE. Upon treatment with highly dosed immunoglobulins and steroid tapering, the patients' muscular symptoms improved while hepatitis resolved. This case highlights the importance of careful evaluation of patients with multifocal motor neuropathy treated with ICIs, highlights the risks of treatment with steroids in multifocal motor neuropathy patients and suggests an alternative treatment of irAEs with intravenous immunoglobulins.