Analysis of Eruptions Caused by Immune Checkpoint Inhibitors

Abstract

A retrospective study was performed in 282 patients who underwent treatment with immune checkpoint inhibitors (ICI) at St. Marianna University Hospital from July 2014 to November 2020. There were 38 patients with 43 lesions that revealed cutaneous immune-related adverse events (irAEs), which were observed more frequently in female patients. The incidence rate of cutaneous irAEs was the highest in malignant melanoma (51.6%) followed by renal cell carcinoma (21.1%), and malignant pleural mesothelioma (20.0%). Cutaneous irAEs occurred in 12.8% of the patients treated with anti-PD-1 antibody, 50.0% of those treated with a combination of anti-PD-1 and anti-CTLA-4 antibodies, and 10.0% of those treated with anti-PD-L1 antibody. As for the types of rashes, maculopapular rash was observed in 21 patients, vitiligo in 11 patients, lichen planus in 3 patients, psoriasis in 3 patients, eruption in 3 patients, bullous pemphigoid in 1 patient, and alopecia in 1 patient. Psoriasis and maculopapular rash appeared early; however, vitiligo and lichen planus appeared later. The Common Terminology Criteria for Adverse Events grade of eruption was 1–2 in 93.0% of the patients, while 7.0% of the patients reported Grade 3. The use of ICI was discontinued in 5 patients. Among the 38 patients, 5 patients had a complete response, 6 had a partial response against the tumor. Seven of these 11 responders were malignant melanoma patients. Regarding malignant melanoma cases, the response rate against melanoma was higher in patients with cutaneous irAEs than those without. Cutaneous irAEs often appear earlier than other irAEs. Most cutaneous irAEs are mild; however, we need to be cautious as severe cases exist. As several points regarding cutaneous irAEs remain unanswered, it is necessary to evaluate more cases and treat those patients in cooperation with other departments.