To investigate the frequency and clinical features of facial palsy (FP) as an immune-related adverse effect.

Monoclonal antibodies to Cytotoxic T-lymphocyte–associated antigen 4 (CTLA-4) [ipilimumab] and programmed cell death (PD1) receptor or ligand (PDL1) [pembrolizumab, nivolumab, atezolizumab] are standard of care treatments for metastatic cancer. The augmented immune response caused by these drugs leads to the emergence of a class of side effects called immune-related adverse effects (irAEs). FP is rarely reported as an irAE.

In this retrospective study, we reviewed the records of 353 patients treated with immunotherapy in our center. 

We identified 4 males and 1 female with FP, ages 39 to 68 (average 55 years old) at the time of the occurrence of FP. Four had metastatic melanoma, all were treated with ipilimumab, monotherapy in one patient, in combination with nivolumab in 2, and with pembrolizumab in one. The remaining patient had metastatic bladder cancer, treated with atezolizumab. FP occurred 1-23 weeks after starting immunotherapy and was unilateral in four patients. In one patient, FP was part of a multifocal neuropathy affecting limb and multiple cranial nerves; in another patient, unilateral FP emerged during the course of a GBS-like condition. Lymphocytic pleocytosis was seen in CSF of three patients who had a lumbar puncture, MRI showed enhancement of the intracranial portion of the affected facial nerve in 4 patients. Four patients were treated with steroids. The outcome was favorable in all of the patients, with the exception of one patient who was lost to follow up.

FP in isolation or as a part of a polyneuropathy is not an uncommon neurological irAE, 1.4% in our cohort, and generally has a good prognosis.