PD-L1 and p16 expression in penile squamous cell carcinoma from an endemic region.

Abstract

515 Background: Penile squamous cell carcinoma (PSCC) is a rare malignancy with limited treatment option in advanced stages. Brazil has one of the highest incidences of PSCC in the world, and different biology has been postulated across distinct populations. We evaluate PD-L1 and p16 expressionand its association with clinical outcomes in PSCC patients from an endemic region. Methods: Formalin-fixed paraffin-embedded (FFPE) specimens were obtained from 35 patients with PSSC. PD-L1 and p16 expression were evaluated by immunohistochemistry. PD-L1 tumor positivity (PD-L1+) was defined as ≥1% tumor cell membrane staining using ZR3 antibody. Any tumor cell membrane staining of p16 was considered positive (p16+). Baseline characteristics including tumor size, stage, grade, subtype, and survival data were collected. Comparisons between PD-L1 and/or p16 expression and clinicopathological features were evaluated using fisher exact testor wilcoxon rank sum tests. Cox model tested the association of PD-L1 and/or p16 expression and 5-year-survival. Results: Clinical features were summarized in table1 according to PD-L1 expression. PD-L1 positivity was significantly associated with larger tumor size ( p=0.027), and p16 expression, a surrogate for HPV infection ( p=0.002). There was a non-statistically significant trend to a shorter 5-year-survival for PD-L1+/p16+ vs. PD-L1-/p16- patients (30.8% vs. 60.6% HR: 2.27 95% CI - 0.61-8.42 p=0.22). Conclusions: PD-L1 expression appears to be associated with p16 expression, larger tumors, higher proliferative rate and worse clinical outcomes in patients with PSCC. provide additional rationale for PD1/PD-L1 inhibitors alone or in combination with chemotherapy foradvanced PSCC in endemic regions. Clinical features. [Table: see text]