PD-1 Is Expressed by Tumor-Infiltrating Immune Cells and Is Associated with Poor Outcome for Patients with Renal Cell Carcinoma
Clinical Cancer Research
Purpose: B7-H1 is expressed by clinically aggressive forms of renal cell carcinoma (RCC) and predicts adverse outcome. B7-H1 is known to impair host immunity via interaction with the Programmed Death-1 (PD-1) receptor, which is expressed by activated Tcells. Levels of immune cells expressing PD-1 (PD-1 + ) in clinical RCC tumors have not been evaluated. Thus, we tested whether immune cell PD-1expression is observed within aggressive RCC tumors. Experimental Design: Between 2000 and 2003, 267
... 00 and 2003, 267 patients underwent nephrectomy at our institution for clear cell RCC and had fresh-frozen tissue available for review. These RCC specimens were immunostained using anti^PD-1 (clone MIH4) and outcome analyses were conducted. Results: Mononuclear immune cell infiltration was observed in 136 (50.9%) specimens. PD-1 + immune cells were present in 77 of these 136 (56.6%) tumors. In contrast, RCC tumor cells did not express PD-1. Patients with PD-1 + immune cells were significantly more likely to harbor B7-H1 + tumor cells (P < 0.001), larger tumors (P = 0.001), and tumors of higher nuclear grade (P = 0.001). Likewise, intratumoral PD-1 + immune cells were associated with advanced tumor-node-metastasis stage (P = 0.005), coagulative tumor necrosis (P = 0.027), and sarcomatoid differentiation (P = 0.008). With a median follow-up of 2.9 years, 52 patients died from RCC. Univariately, patients with PD-1 + immune cells were at significant risk of cancer-specific death compared with PD-1 À patients (risk ratio, 2.24; P = 0.004). Conclusions: Levels of immune cells expressing PD-1were increased in patients with high-risk RCC tumors. Interactions between immune cell PD-1and B7-H1may promote cancer progression by contributing to immune dysfunction in patients with RCC.