PD-L1 Expression Reveals Significant Association With Squamous Differentiation in Upper Tract Urothelial Carcinoma.

Abstract

Limited literature is available on the tumor microenvironment (TM) of upper tract urothelial carcinoma (UTUC). This study comprehensively reviews programmed death 1 receptor (PD-1)-positive and CD8+ tumor-infiltrating lymphocytes (TILs) and programmed death ligand 1 (PD-L1) expression on tumor epithelium (TE). Seventy-two nephroureterectomy specimens were analyzed for PD-L1, PD-1, and CD8. One percent or more tumor and lymphohistiocyte PD-L1 expression was considered positive. TIL density by H&E was scored semiquantitatively from 0 to 3, and CD8+ and PD-1+ TILs were quantified in hotspots. Of the cases, 37.5% demonstrated PD-L1+ on TE. PD-L1+ TE showed an association with pathologic stage (P = .01), squamous differentiation (SqD) (P < .001), TILs by H&E (P = .02), PD-1+ peritumoral TILs (P = .01), and PD-L1+ peritumoral lymphohistiocytes (P = .002). Finally, there was a significant difference in PD-1+ peritumoral TILs in cases with SqD vs no SqD (P = .03). Aggressive UTUC is associated with a distinct TM. Furthermore, TM of UTUC-SqD was distinctly different from those with no SqD, warranting study in a larger cohort.