Background/Purpose: Immune checkpoint inhibitors have revolutionized the treatment of advanced malignancies. By blocking T-cell inhibition these drugs result in immune targeting of tumor cells and normal tissue. As such, their main toxicity is inducing immune-mediated tissue damage. Patients with preexisting rheumatologic diseases were excluded from the clinical trials for these agents, and little is known about the safety, efficacy, or risk for disease flares in these patients.

Methods: A retrospective medical record review was performed to identify all patients who received checkpoint inhibitor therapy at Mayo Clinic, Rochester between 2011 and 2016. Those with preexisting rheumatologic disease were identified using specific diagnostic codes.

Results: There were 16 patients identified (81% female, mean age 68.3). The most common rheumatologic diseases were rheumatoid arthritis (5), polymyalgia rheumatica (5), Sjogren’s syndrome (2), and systemic lupus erythematosus (2). Seven patients were receiving treatment with immunosuppressive therapy upon starting a checkpoint inhibitor. The primary malignancies were melanoma (10), pulmonary (4), or hematologic (2). In most cases checkpoint inhibitors were offered only after failure of several other therapies. Immune-related adverse events (IRAE) occurred in 6 patients and all were treated successfully with corticosteroids and discontinuation of therapy. Survival was significantly prolonged in patients with an IRAE (17 months vs. 1.4 months [p=0.003]). There were no significant differences in time from cancer diagnosis to immunotherapy, duration of immunotherapy, age, or sex between these groups.

Conclusion: To our knowledge, this represents the largest single-center cohort of patients with rheumatologic diseases who were exposed to cancer immunotherapy. Only a minority of these patients experienced a flare of their preexisting rheumatologic disease or any other IRAE. The presence of an IRAE was associated with significantly prolonged survival.