Neurologic Outcomes in People With Multiple Sclerosis Treated With Immune Checkpoint Inhibitors for Oncologic Indications.

Background and objectives: Immune checkpoint inhibitors (ICIs) are increasingly used against various cancers but are associated with immune-related adverse events (irAEs). Risk of irAEs may be higher in patients with certain preexisting autoimmune diseases, and these patients may also experience exacerbation of the underlying autoimmune disease following ICI initiation. People with multiple sclerosis (MS) have mostly been excluded from clinical trials of ICIs, so data on the safety of ICIs in MS are limited. This study aims to assess the rate of MS activity, as well as neurologic and nonneurologic irAEs in persons with MS treated with ICIs for cancer.

Methods: Participating sites were invited to this retrospective observational study through the Medical Partnership 4 MS+ listserv. Seven large academic centers participated in the study, each conducting a systematic search of their electronic medical record system for patients with MS and history of ICI treatment. The participating neurologist reviewed each chart individually to ensure the inclusion criteria were met. Demographics and data on MS and cancer history, treatments, and outcomes were abstracted from patient charts using a structured instrument.

Results: We identified 66 people with MS (median age 66 years, 73% female, 68% not on disease-modifying therapy for MS) who were treated with ICIs for lung cancer (35%), melanoma (21%), or another oncologic indication. During post-ICI follow-up (median: 11.7 months, range 0.2-106.3 months), 2 patients (3%) had relapse or MRI activity, 3 (5%) had neurologic irAEs, and 21 (32%) had nonneurologic irAEs. At the last follow-up, 25 (38%) participants had partial or complete remission of their cancer, while 35 (53%) were deceased.

Discussion: In this multi-institutional systematic retrospective study of predominantly older patients with MS, most of whom were not on disease-modifying therapy, MS activity and neurologic irAEs following ICI treatment were rare. These data suggest that preexisting MS should not preclude the use of ICIs for cancer in older patients, but the results may not be generalizable to younger patients with active MS. Prospective studies of ICI safety that enroll younger patients with MS are needed.