To analyze characteristics and neurologic outcomes of multiple sclerosis (MS) patients who received immune checkpoint inhibitor (ICPI) treatment for malignancy.

ICPIs are currently approved to treat a growing number of cancers but can also cause autoimmune adverse events. There is concern that ICPIs can provoke relapses in patients with MS.

16 patients (12 female) were identified with an average [SD] age of 67.4 [11.9] years. 12 (75%) had relapsing remitting multiple sclerosis, and 4 (25%) had secondary progressive multiple sclerosis.  The average [SD] disease duration was 26.8 [11.2] years. 3 patients were on disease modifying therapy (1 on interferon beta-1b, 1 on glatiramer acetate, and 1 on dimethyl fumarate). 11 (68.8%) never had a relapse since MS diagnosis.  

The majority of patients had either non-small cell lung cancer (n=7) or melanoma (n=6).  The average number of cycles [SD] of immunotherapy was 15.3 [15.6], with the majority of patients, 9 (62.5%), receiving pembrolizumab as their first ICPI. 50% of patients had an ICPI systemic adverse event. No patients had MS relapses after ICPI treatment though two patients had symptom recrudescence. Of the 12 patients who had brain MRIs post ICPI, no patients had new MS lesions.

ICPI use in this cohort was not associated with MS relapses or new MRI lesions. However, patients in this cohort were older and had benign or inactive MS. Larger studies are needed in MS patients on ICPIs to further understand the risk of MS relapses and disease progression.