Pembrolizumab-Induced Acral Vasculitis

Abstract

Immune checkpoint inhibitors (ICIs) have emerged as groundbreaking new therapies for a variety of solid tumors. ICIs stimulate the host immune system to attack cancer cells. However, this nonspecific immune activation can cause autoimmunity across multiple organ systems—this is referred to as an immune-related adverse event. Vasculitis secondary to ICI administration is an extremely rare event seen in <1% of cases. We identified 2 cases of pembrolizumab-induced acral vasculitis at our institution. The first patient, with stage IV adenocarcinoma of the lung, developed antinuclear antibody–positive vasculitis 4 months after initiation of treatment with pembrolizumab. The second patient had stage IV oropharyngeal cancer and presented with acral vasculitis 7 months after starting pembrolizumab. Unfortunately, both cases resulted in dry gangrene and poor outcomes. Here, we discuss the incidence, pathophysiology, clinical features, treatment, and prognosis of patients with ICI-induced vasculitis with the intention of raising awareness about this rare and potentially fatal immune-related adverse event. Early diagnosis and discontinuation of ICIs are critical for improving clinical outcomes in this situation.