To determine the risk of rheumatic disease flare and adverse effects in patients with preexisting rheumatic disease who were receiving immune checkpoint inhibitor (ICI) therapy.

A retrospective medical record review was performed to identify all patients who received ICI therapy at Mayo Clinic in Rochester, Minnesota between 2011 and 2016 (~700 patients). Those with a preexisting rheumatic disease were identified using specific diagnostic codes.

Sixteen patients were identified (81% female, median age 68.5 years). The most common rheumatic diseases were rheumatoid arthritis (n = 5), polymyalgia rheumatica (n = 5), Sjögren's syndrome (n = 2), and systemic lupus erythematosus (n = 2). Seven patients were receiving immunosuppressive therapy or glucocorticoids for their rheumatic disease at the time of initiation of the ICI. The primary malignancies were melanoma (n = 10), pulmonary (n = 4), or hematologic (n = 2). In most cases, ICIs were offered only after failure of several other therapies. Immune-related adverse effects (IRAEs) occurred in 6 patients, and all were treated successfully with glucocorticoids and discontinuation of the ICI therapy. There were no significant differences in time from cancer diagnosis to immunotherapy, duration of immunotherapy, age, or sex between the patients with and those without IRAEs.

To our knowledge, this represents the largest single-center cohort of patients with rheumatic diseases who were exposed to modern cancer immunotherapy. Only a minority of these patients experienced a flare of their preexisting rheumatic disease or any other IRAE.