Case Report and Literature Review on Skin Toxicity Induced by PD-1 Inhibitor in a Penile Cancer with Massive Ulceration of Chemoradiotherapy-Resistant and Successful Treatment by Immunotherapy

Penile cancer is a rare malignant tumor with a poor prognosis in advanced stages. Immune checkpoint inhibitors (ICIs) have demonstrated promising efficacy in patients with advanced penile cancer, but it can also induce immune-related adverse events (irAEs). This article reports a patient who achieved almost a complete response to the PD-1 inhibitor sintilimab as third-line treatment for advanced penile squamous cell cancer with massive ulceration of chemoradiotherapy-resistant, and successful treatment by immunotherapy. One year into maintenance therapy with sintilimab, skin toxicity in the form or grade-2 skin rashes and grade-3 pruritus occurred. Sintilimab was permanently discontinued. The skin toxicity was effectively controlled by oral prednisone at a daily dosage of 15 mg. At the last follow-up of 16 months after sintilimab discontinuation, the patient remained in partial response, with total progression-free survival exceeding 30 months. We also conducted a comprehensive literature search, and summarized skin toxicity of ICIs administration. These articles suggested that immune-related skin toxicity may be indicative of good treatment response.