Trial Information

T Regulatory Cells in Renal Cell Carcinoma (PILOT STUDY)

T regulatory cells (T regs) are a recently identified subset of T cells with inhibitory
functions on the immune system. In cancer, it has been shown that there is an increased
proportion of T regs in several different human malignancy states. T regs are found to be
elevated in peripheral blood mononuclear cells, draining lymph nodes and in the primary
tumor itself. There has also been correlation between peripheral blood T regs and tumor
stage, tumor relapse and survival. It has been proposed that the T regs are activated and
expanded by factors produced by the tumor microenvironment. They are thought to play a role
in preventing or demising host T-cell responses against cancer, including a suboptimal host
responses to vaccine strategies. Strategies to reduce T regs in cancer patients are being
explored as a novel immunologic anti-cancer approach.

Renal cell cancer (RCC) is a tumor with well-known immune-mediated phenomena such as
spontaneous regression. There is paucity of data on T regs in RCC. We propose to study the
frequency of peripheral blood T regs before and after nephrectomy for RCC. We will document
the baseline frequency of T regs in RCC and if nephrectomy results in a change in levels. We
hypothesize that nephrectomy will lower peripheral T regs to normal levels in early stage
RCC, and will reduce peripheral T reg levels in advanced RCC patients. If found to be so, T
regs could in future be used as an indicator of disease recurrence in early stage RCC. In
advanced RCC, lowering of T reg levels may help explain the previous hypothesis that
debulking nephrectomy results in improved anti-tumor immunity, provide rationale for second
debulking procedures, and be correlated with subsequent clinical course.

The main laboratory technique is flow cytometry. This will be a pilot study with small
patient numbers. Only blood samples are required.