Efficacy and safety of immune checkpoint inhibitors in metastatic penile squamous cell carcinoma: a retrospective multicenter analysis.

Penile squamous cell carcinoma (PSCC) is a rare malignancy, and first-line therapy typically involves cisplatin-based chemotherapy. However, these regimens are often unsuitable for patients with poor performance status or advanced age due to their toxicity. This retrospective, multicenter study evaluated patients with metastatic PSCC who received immune checkpoint inhibitor (ICI) therapy between 2017 and 2024. A total of 10 patients met the inclusion criteria. The median age was 75 years, and 50% had an ECOG performance status of 2 or higher. The objective response rate (ORR) was 30%, and the disease control rate (DCR) was 40%. The duration of response and disease control was over 12 months and 8 months respectively in all patients with response or disease control. The median progression-free survival (PFS) was 2.82 months, and the median overall survival (OS) was 4.32 months. PD-L1 and HPV-positive patients had a 67% response rate (n = 2/3). No patients experienced severe immune-related adverse events (irAEs). This multicenter retrospective analysis suggests that ICI monotherapy may be a promising treatment option for patients with advanced PSCC who are either ineligible for first-line platinum-based chemotherapy or who have progressed after platinum-based chemotherapy, including those with poor performance status. Further studies are needed to confirm these findings and identify baseline patient characteristics that may optimize selection criteria.