Clinical Significance of PD-L1 Expression in Both Cancer and Stroma Cells of Cholangiocarcinoma Patients.

Abstract

The clinical significance of programmed death 1 and its ligand (PD-L1) as therapeutic targets has been reported previously. This study aimed to investigate the clinical impact of PD-L1 expression in cancer and stroma cells in cholangiocarcinoma (CCA). The study enrolled 177 consecutive CCA patients who underwent curative resection between 2005 and 2014. Expression of PD-L1 in CCA and stroma cells was assayed by immunohistochemistry, and their relationships with patient clinicopathologic characteristics and prognoses were evaluated. Tumor-infiltrating immune cells (CD66b+ neutrophils [TANs] and CD163+ M2 macrophages [TAMs]) also were assayed by immunohistochemistry, and their relationship with PD-L1 expression in cancer and stroma cells was evaluated. Among the 177 analyzed CCA cases, PD-L1 expression was identified in cancer cells in 54 cases (30.5%) and in stroma cells in 77 cases (43.5%). The patients with positive PD-L1 expression in cancer and stroma cells had worse overall survival rates than those negative for PD-L1 (cancer cells: hazard ratio [HR] 2.08; P = 0.0004; stroma cells: HR 1.84; P = 0.003). Moreover, the patients with PD-L1-positive cancer cells had higher rates of PD-L1 expression in stroma cells (P < 0.0001) and higher numbers of TANs (P = 0.0003) and TAMs (P = 0.004) than those with low PD-L1 expression. In the multivariate analysis, PD-L1 expression in both cancer and stroma cells (HR 2.20; P = 0.002) was an independent predictor of poor overall survival. The study showed PD-L1 expressed in both CCA and stromal cells and demonstrated that its expression may affect numbers of TANs and TAMs and play a pivotal role in CCA outcomes.