Circulating endothelial cells are a potential biomarker for patients with renal cell carcinoma (RCC) with and without von Hippel Lindau (VHL) syndrome

Abstract

5098 Background: VHL is a primary cause of inherited RCC and 60% of sporadic clear cell RCCs have mutations in the VHL gene. RCCs often remain asymptomatic for long intervals. Diagnosis during presymptomatic screening has the potential to improve overall outcome. Circulating endothelial cells (CECs) are a potential biomarker for monitoring angiogenesis. Mature CECs are thought to be shed from existing vessels while circulating endothelial progenitors (CEPs) are thought to be derived from bone marrow. We sought to assess the potential of CECs and CEPs as markers of RCC in pts with VHL and sporadic RCC. Methods: Batch analysis of PBMCs obtained from consenting pts with sporadic or VHL associated RCC, VHL (without RCC), and normal volunteers (NV) was performed FACS analysis was performed using a panel for four antibodies including CD45, CD31, CD146, and CD133. CECs were defined as CD45-, CD31+ and CD146+, and CD133-. CEPs had the same phenotype but were CD133+. Results: RCC pts have higher CECs, CEPs and CEP/CEC ratio as compared to NV (p<0.05 for each comparison). Additionally, these 3 parameters were similar in NV and pts with VHL without RCC. However pts with VHL and RCC had significantly higher CEP/CEC ratio and CEP values than pts with VHL without RCC. (p<0.05 for each comparison) (Table). Conclusions: CECs are a potential biomarker for RCC in pts with sporadic RCC. These data suggests that CEPs and CEP/CEC ratio may represent a screen that may allow for the early detection of RCC in VHL pts. Larger studies will be needed to validate these findings. Supported by VHL Family Alliance (Joyce Graff Director) the DF/HCC Kidney Cancer SPORE P50CA101942, and the ASCO YIA. Average CEC (cells/ul) Average CEP (cells/ul) Average CEP/CEC RCC (n=10) * 2.36 2.08 1.97 NV (n=17) 0.45 0.21 0.61 VHL (without RCC) (n=13) 0.54 0.19 0.67 VHL (with RCC) (n=6) 3.16 2.91 2.76 * includes pts with VHL and RCC (n=6) and pts with sporadic RCC (n=4). No significant financial relationships to disclose.