Cutaneous adverse events of immune checkpoint inhibitor therapy: incidence and types of reactive dermatoses

Background Dermatoses are common and potentially serious complications of programmed cell death receptor PD-1 immune checkpoint inhibitor (anti-PD-1 ICI) therapy. Understanding their incidence is necessary to support clinical awareness, diagnosis, and management. Objective To examine the incidence and odds of reported non-cancerous dermatoses in the setting of anti-PD-1 ICI therapy. Methods Cross-sectional study of anti-PD-1 (pembrolizumab or nivolumab) treated patients at a tertiary healthcare institution. Selected dermatologic events following immunotherapy were identified in the electronic medical record. Comparator arm were patients that developed these same dermatoses without receiving anti-PD-1 ICI therapy. Results There were 13.7% (254/1857) patients that developed one of 28 dermatoses. Compared with the general population, patients treated with anti-PD-1 had a greater risk for development of mucositis (OR 65.7, 95% CI 35.0–123.3), xerostomia (OR 11.9, 95% CI 8.4–16.8), pruritus (11.3, 95% CI 8.9–14.3), and lichen planus/lichenoid dermatitis (OR 10.7, 95% CI 5.6–20.7). Conclusions We report the frequency of dermatoses encountered in the setting of ICI therapy, both common (pruritus, rash, vitiligo) and uncommon (scleroderma, urticaria).