Cutaneous Side Effects of PD-1 Inhibitors: A Single-Center Retrospective Study

The introduction of immune checkpoint inhibitors (ICIs) opened a new era in cancer immunotherapy. In particular, PD-1 inhibitors have shown remarkable efficacy in various cancers, most notably melanoma. However, the widespread use of immune checkpoint inhibitors comes with the challenge of immune-related adverse events (irAEs), with cutaneous toxicities being the most prevalent.

A retrospective, single-center study was carried out to investigate the cutaneous side effects in patients diagnosed with melanoma and treated with PD-1 inhibitors (pembrolizumab or nivolumab) at the Department of Dermatology, Venereology, and Oncodermatology, University of Pécs, Hungary. The study included patients with stage III or IV melanoma who received PD-1 inhibitor monotherapy, either for metastatic or adjuvant purposes, from August 2015 to May 2022.

A cohort of 174 patients was examined, with 29% experiencing cutaneous adverse events (cAEs). The most prevalent cutaneous toxicities were vitiligo (n = 18; 27%), maculopapular rash (n = 14; 21%), pruritus (n = 14; 21%), xerostomia (n = 8; 12%), and lichenoid dermatitis (n = 4; 6%). Treatment primarily involved topical corticosteroids and emollients, with a few cases requiring systemic therapy. Notably, the occurrence of dermatologic adverse events was associated with improved progression-free survival (PFS) (p = 0.007) and overall survival (OS) (p = 0.026) compared to those without any skin toxicity (p < 0.0001), emphasizing their potential prognostic significance. Our data were not influenced by any well-known prognostic factors of melanoma.

Our study contributes to the growing body of evidence supporting the prognostic value of cutaneous adverse events in patients treated with PD-1 inhibitors. Optimizing treatment strategies while maintaining oncologic therapy is essential, highlighting the role of dermatologists in multidisciplinary cancer care.