Cutaneous immune-related adverse events: incidence rates, risk factors and association with extracutaneous toxicity - a prospective study of 189 patients treated with checkpoint inhibitors at a Spanish tertiary care hospital.

Background: Clinicians are increasingly prescribing immune checkpoint inhibitors (ICIs) to treat cancer, but the real-world incidence, characteristics and risk factors of cutaneous immune-related adverse events (cirAEs) are unclear.

Objectives: To determine the incidence, features and risk factors of cirAEs and to measure their possible association with extracutaneous toxicity.

Methods: We conducted a prospective observational study in a Spanish tertiary care hospital, including people who started an ICI between March 2020 and May 2022. We used a survival analysis and a log-rank test to obtain and compare incidence rates, and a multivariate Cox model to detect risk factors for cirAEs.

Results: We included 189 patients, 82 (43.4%) of whom presented cutaneous toxicity. The incidence of cirAEs was 75.0 per 100 person-years, with a 50.0% probability of the appearance of a cirAE at 10 months of follow-up. The most frequent cirAE category was inflammatory dermatoses, and the most frequent types were pruritus, eczema and maculopapular eruptions. ICI combination therapy, a family history of psoriasis and rheumatological and pulmonary immune-related adverse events increased the risk of cirAEs.

Conclusions: We found a high incidence of cirAEs, and they occurred early in the follow-up period. Dermatologists should be involved in the management of cirAEs, especially in people with risk factors.