Prognostic role of programmed cell death protein 1 expression in surgically treated patients with upper tract urothelial carcinoma.

402 Background: Programmed cell death protein (PD-1) expressed on active T cells, and its ligand PD-L1 expressed on the surface of cancer cells, complementarily down-regulate T cell activation and are related to immune tolerance. A close association between PD-1 expression and poor prognosis has been reported in several cancers, however, in upper tract urothelial carcinoma (UTUC) the role of PD-1 expression on clinical outcome has not been investigated. Methods: The protein expression of PD-1 was evaluated by immunohistochemistry and the relationship with clinicopathological features was investigated in surgical specimens obtained from 100 patients who had been surgically treated for UTUC. At a magnification of 200x, PD-1 protein expression was estimated and the positive cells were graded as no (negative), moderate (1-10 cells), and strong ( > 10 cells). Results: Twenty-four patients (24.0%) had strong PD-1 staining, 32 patients (32.0%) had moderate PD-1 staining, and 44 patients (44.0%) had no PD-1 staining. PD-1 staining was associated with pathological T stage (p = 0.023), tumor grade (p = 0.005), and lymphovascular invasion (p = 0.033). Lymphovascular invasion (p < 0.001) and PD-1 staining (p = 0.02) were independent factors for predicting disease metastasis. The 5-year matastatic free survival rate in patients with strong PD-1 staining was 57.3 %, which was significantly lower than that with no PD-1 staining (87.3%, p=0.001) and that with moderate PD-1 staining (74.3%, p = 0.05). In a sub-group analysis of patients with ≥pT2 (N = 59), a significant difference in disease metastasis was observed between patients with strong PD-1 staining and no PD-1 staining (p = 0.018), but was not observed between strong and moderate PD-1 staining (p = 0.146). Conclusions: PD-1 expression may be a useful indicator for a worse prognosis in UTUC patients who undergo radical nephroureterectomy. Targeting therapy against PD-1 might be a promising therapeutic modality for UTUC.