A Case Series of Raynaud's Phenomenon in the Setting of Immune Checkpoint Inhibitors.

Although immune checkpoint inhibitors (ICIs) have improved oncological outcomes, they can cause a myriad of inflammatory conditions known as immune-related adverse events (irAEs). Raynaud's phenomenon (RP) is a rare rheumatologic irAE that may arise de novo or present as an exacerbation of preexisting disease. This case series aims to describe ICI-induced RP in patients without a rheumatological diagnosis seen at a large, specialized cancer center. Our case series describes five patients with ICI-induced RP who were evaluated by rheumatology at a cancer center during the past 3 years where their cancers, type of ICIs, diagnostic tests, and treatments are discussed in detail. Among our five patients, one patient had preexisting psoriatic arthritis, and one had preexisting RP. The outcome of our patients' ICI-induced RP varied widely. Although three patients had significant digital ischemia resulting in ulceration requiring epoprostenol infusions, the remaining two patients had mild digital ischemia that were controlled conservatively. However, none of our patients had clinical features to suggest systemic sclerosis (SSc), where RP is often the first symptom. Interestingly, interferon-γ and interleukin-6 were the most frequently elevated cytokines when checked in these patients. This is the first case series, to the authors' knowledge, to describe ICI-induced RP, which may occur without other clinical features of an autoimmune rheumatological disease. The severity of the disease may vary, but it warrants increased awareness and prompt initiation of appropriate treatment.