Programmed Death Ligand-1 Expression Is Associated With Poorer Survival in Anal Squamous Cell Carcinoma

Abstract

Context.— Upregulation of programmed death ligand-1 (PD-L1), an immunoregulatory protein, is associated with an adverse outcome in several malignancies. Very few studies have evaluated PD-L1 expression in invasive anal squamous cell carcinoma (ASCC). Objective.— To assess PD-L1 expression in patients with ASCC and correlate it with clinicopathologic factors and clinical outcomes. Design.— Fifty-one cases of ASCC were immunostained for PD-L1. PD-L1 expression by combined positive score and tumor proportion score was correlated with age, gender, HIV status, HIV viral load, CD4 count, stage, and outcomes. Kaplan-Meier curves for overall survival were plotted and compared using the log-rank test. Cox regression analysis was performed to identify significant prognostic factors (2-tailed P < .05 was considered statistically significant). Results.— PD-L1 was positive in 24 of 51 cases (47%) by combined positive score and in 18 of 51 (35%) by tumor proportion score. The median cancer-specific survival and 5-year overall survival were significantly lower in PD-L1+ patients. Age, gender, HIV status, HIV viral load, stage, and cancer progression were not significantly different between the two groups. CD4 count of more than 200/μL was significantly higher in PD-L1+ patients. PD-L1+ status remained statistically significant for worse overall survival on multivariate analysis. Conclusions.— PD-L1+ status is an independent adverse prognostic factor for overall survival in ASCC. This study highlights the potential of PD-L1 targeted therapy in better management of ASCC.