PD-L1 Expression in Men with Penile Cancer and its Association with Clinical Outcomes

It has been hypothesized that PD-L1 expression in tumor cells and tumor-infiltrating immune (TII) cells may contribute to tumor progression by inhibiting antitumor immunity.

To investigate the association between PD-L1 expression in tumor cells and TII cells and clinical outcomes in penile cancer.

A cohort of 222 men treated for penile squamous cell carcinoma (SqCC) at Örebro University Hospital between 1984 and 2008 with long-term follow-up (median 34 mo) was evaluated for PD-L1 expression in tumor cells and TII cells via immunohistochemistry.

Association between clinicopathological features and PD-L1 expression was estimated using χ² and Fisher's exact tests. For survival analyses, Kaplan-Meier curves with log-rank tests and multivariate Cox proportional hazards regression models were used.

We found that 32.1% of the tumors and 64.2% of the TII cells expressed PD-L1. Our data demonstrate that penile SqCC patients with PD-L1-positive tumor cells or TII cells are at significant risk of lower cancer-specific survival and that the prognostic value of PD-L1 expression was strongest for tumor cell positivity. The use of tissue microarrays rather than whole sections may be viewed as a limitation.

Tumor PD-L1 expression independently identifies penile SqCC patients at risk of poor clinical outcomes.

We investigated how many patients with penile cancer had tumors that manufactured PD-L1, a protein that decreases the ability of the immune system to fight cancer. We found that up to one-third of penile tumors make this protein. Patients whose tumors make PD-L1 have more aggressive penile cancer and worse clinical outcomes.