CNS and PNS manifestation in immune checkpoint inhibitors: A systematic review

Immunomodulatory therapies, including the use of immune checkpoint inhibitors (ICIs), have made a profound impact on treatment of advanced cancers in recent decades. Neurologic immune-related adverse events (irAEs) related to use of these agents are rare but potentially fatal sequelae. This systematic reviewed aimed to describe onset, clinical features, treatment, and outcome of neurological irAEs following ICI usage.

A systematic literature search was conducted to identify all case reports (n = 168) and case series (n = 29) describing neurological irAEs (n = 255 patients). Patient demographics, clinical features, and clinical courses were extracted and used to assess statistical relationships between reported variables.

Of reports describing neurological irAEs related to ICI use, the majority of cases were in men (66%) and patients above the age of fifty (85%). Disorders of the peripheral nervous system (PNS, 83%) were more common than central nervous system involvement. Neuromuscular disorders were the most common type of neurological irAE (e.g. myasthenia gravis, 36%), followed by peripheral neuropathies (16%), followed by all CNS disorders combined (15%). Most cases presented within the first 5 doses of ICI treatment. Most patients improved clinically, but 24% of cases were fatal. Mortality was highest in patients with neuromuscular irAEs, such as myasthenia gravis and myositis.

This systematic literature review describes the largest collection of neurological irAEs to date including both CNS and PNS manifestations of ICIs. The information described herein can be used to better inform monitoring and treatment of patients undergoing treatment with ICIs.