Immune checkpoint inhibitor-induced myocarditis and multiple adverse events with pre-existing rheumatoid arthritis: a case report and literature review.

Abstract

Immune checkpoint inhibitors (ICIs) can trigger immune-related adverse events (irAEs) and rheumatoid arthritis (RA) reactivation in cancer patients with pre-existing RA. Studies indicate RA reactivation occurs in approximately 50% of these patients, while new irAEs develop in 25-50% of ICI-treated patients. Furthermore, ICI-induced myocarditis has been reported to have a high mortality rate, ranging from 25% to 50%. No prior reports have detailed the clinical course of ICI-induced myocarditis in patients with RA. We describe a 77-year-old man with RA who developed myocarditis, myositis, and RA flare following treatment with the PD-LI inhibitor, atezolizumab, for small-cell lung cancer. High-dose glucocorticoid (GC) therapy and intravenous immunoglobulin improved myocarditis and myositis. Corticosteroid tapering led to organizing pneumonia, necessitating a dosage adjustment. Once resolved, tapering resumed. During irAEs treatment, the patient maintained a partial response without cancer recurrence for ten months, and required no further cancer-specific therapy. To our knowledge, this is the first detailed report of ICI-induced myocarditis in a patient with pre-existing RA. Our findings emphasize the importance of vigilant monitoring of both irAEs and RA disease activity for optimal patient management.