Hypoxia-inducible factor (HIF) 1α and 2α as predictive markers of outcome to VEGFR tyrosine kinase inhibitors (TKI) in renal cell carcinoma (RCC).

4630 Background: Relevant biomarkers in RCC are needed to identify appropriate candidates for selected targeted therapies. Mutations in the von Hippel-Lindau (VHL) gene result in the accumulation of HIF and increased expression of proangiogenic factors, including VEGF. Methods: Metastatic clear RCC patients with available baseline tumor samples who received first-line oral VEGFR-TKI were included in this analysis. VHL mutation/hypermethylation status and HIF1α and HIF2α immunohistochemical staining were analyzed from paraffin-embedded tumors. Additionally, a panel of candidate VEGF and VEGFR2 genetic SNPs was determined from peripheral blood samples. HIF was scored as negative or positive based on staining intensity (0-10% and > 10%, respectively). Results were evaluated for associations with clinical outcome. Results: 80 patients were included: 71 evaluable for HIF expression, 63 for VHL status and 52 for SNPs. 73% received treatment with sunitinib and median follow-up was 21.5 months. Unlike VHL status,...