Recurrent Metastatic Penile Cancer Patient with Positive PD-L1 Expression Obtained Significant Benefit from Immunotherapy: A Case Report and Literature Review

BACKGROUND: Penile squamous cell carcinoma (PSCC) bears poor prognosis due to its rarity and limited treatment options, especially after failure of standard treatments. Effective therapeutic options were desperately needed. CASE PRESENTATION: We report a recurrent metastatic PSCC patient with positive programmed death ligand 1 (PD-L1) expression (≥10%) and tumor mutation burden (TMB) of 8.87 (Muts/Mb) who obtained significant response to immunotherapy, with progression-free survival (PFS) exceeding 10 months. CONCLUSION: This is the first case presenting remarkable response to immunotherapy in a Chinese PSCC patient. The remarkable response might be associated with PD-L1 expression, indicating that PD-L1 expression could be a promising biomarker for immunotherapy in PSCC. TMB ranking may also contribute to patient selection. However, large clinical trials are needed to validate these notions.