UroToday- It has been reported widely that expression of B7-H1 by renal cell carcinoma (RCC) is associated with an adverse outcome. B7-H1 is thought to interact with specific receptors on activated T cells to inhibit antitumoral immunity by the host. One such receptor is the programmed death receptor 1 (PD-1). Here, the group from Mayo examines expression of the PD-1 receptor by tumor infiltrating lymphocytes and correlates that expression with outcomes.

The authors examined 267 specimens of clear cell RCC and found that 50.9% had mononuclear cell infiltration. Of these, 56.6% were found to exhibit PD-1 expression on the infiltrating mononuclear cells. PD-1 expression was not associated with the tumor cells themselves. Patients with PD-1 positive infiltrating lymphocytes were more likely to express B7-H1, have larger tumors, increased grade, increased TNM stage, have coagulative necrosis, have sarcomatoid features, and present with tumor related symptoms. In univariate analysis the presence of PD-1 positive lymphocytes was associated with an increased risk of death from RCC (RR 2.24, p=0.004) however, this lost significance after controlling for either the presence of a lymphocytic infiltrate or the Mayo SSIGN score.

The authors conclude that the presence of PD-1 positive tumor infiltrating lymphocytes is associated with an adverse outcome in patients with clear cell RCC, and that it is in part through the interaction with this receptor that B7-H1 acts to allow the tumor to evade the host immune system.

Thompson RH, Dong H, Lohse CM, Leibovich BC, Blute ML, Cheville JC, Kwon ED

Clin Cancer Res. 13(6):1757-1761, March 2007
doi: 10.1158/1078-0432.CCR-06-2599

Reported by UroToday Contributing Editor Christopher G. Wood, MD

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