Bell's palsy during rechallenge of immune checkpoint inhibitor.

Introduction: The peripheral nervous system is one of the target organs of immune-related adverse events. Peripheral facial nerve palsy, also called Bell's palsy, which is induced by immune checkpoint inhibitors, is quite rare, and its clinical features are not well known.
Case Presentation: A man with renal cell carcinoma who received rechallenging immune checkpoint inhibitor therapy developed unilateral facial palsy and was diagnosed with Bell's palsy. He did not have any severe immune-related adverse events during his previous immune checkpoint inhibitor treatment. Corticosteroid therapy was immediately initiated, and his facial palsy symptoms promptly improved.
Conclusion: Physicians should be aware that Bell's palsy can occur as an immune-related adverse event. Additionally, careful observation is necessary during rechallenge with immune checkpoint inhibitors, even in patients who did not have previous immune-related adverse events.
Competing Interests: The authors declare no conflict of interest. Except for Yuji Miura: personal fees from Ono Pharmaceutical, Bristol Myers Squibb, MSD, and Takeda; Advisory Board personal member of Chugai Pharmaceutical Co. and Takeda; Local PI and Institutional Financial interest from MSD and Ono Pharmaceutical. All of them are outside the submitted work.
(© 2023 The Authors. IJU Case Reports published by John Wiley & Sons Australia, Ltd on behalf of Japanese Urological Association.)