Autoimmune Bell's Palsy Following Immunotherapy For Metastatic Melanoma: A Report of 2 Cases.

By targeting receptors that serve to downregulate the cellular immune system, monoclonal antibodies such as ipilimumab and nivolumab have transformed the management of metastatic melanoma, and their use is referred to as immune checkpoint therapy (ICT). However, because the antitumoral activity of these agents is achieved through the reversal of mechanisms that naturally serve to temper the immune response, the potential for adverse reactions secondary to autoimmunity is of clinical significance. Neurological immune-related adverse events (irAEs) may occur consequent to ICT, and the development of autoimmune Bell's palsy is a specific, uncommon manifestation of the body's immune response against the seventh cranial nerve, resulting in acute paresis of facial muscles. We describe 2 cases of autoimmune Bell's palsy following the administration of combination ICT using ipilimumab and nivolumab in 2 patients with metastatic melanoma. The use of a steroid taper in addition to the cessation of combination immunotherapy resulted in resolution of symptoms for both patients. In the first case, the patient was subsequently started on nivolumab monotherapy but developed autoimmune polyneuropathy, and immunotherapy was discontinued indefinitely. In the second case, the initiation of nivolumab monotherapy following resolution of symptoms resulted in an inadequate antitumoral response. Subsequent transition to treatment with encorafenib/binimetinib initially provided a positive response but also required discontinuation secondary to irAEs. Both of these cases demonstrate the potential for autoimmune Bell's palsy as a consequence of combination ICT and provide evidence of successful treatment of this irAE through temporary discontinuation of immunotherapy and administration of steroids.