Long-term nivolumab treatment possibly associated with aseptic meningitis.

Nivolumab is a programmed death-1 receptor blocker within the family of medications called immune checkpoint inhibitors (ICIs). Although generally well tolerated, cases of immune-related adverse events (irAEs) have been reported. We present a case of a man being treated with nivolumab for renal cell carcinoma who presented to the emergency department with problems of headache, fever and disorientation. After extensive evaluation, a diagnosis of immunotherapy-induced aseptic meningitis was considered more probable than infectious. Due to stable clinical status, no treatment was initiated, and the patient's condition improved spontaneously. The patient was discharged home. To date, only a handful of prior cases of nivolumab-induced meningitis have been reported. Our case demonstrates that irAEs can occur years after the initiation of ICIs. This was a milder presentation of a neurological irAE that resolved spontaneously with watchful waiting, showing that irAEs are likely an evolving spectrum of disease for which clinicians should be aware.