Specific HIF-2α inhibition resulted in tumor regression in a subset of ccRCC cell line xenografts in mouse models of primary and metastatic ccRCC, in 10 of 18 patient-derived RCC xenografts in mice, and a patient with extensively pretreated metastatic ccRCC, who remained progression free for 11 months. This evidence concerns the gene EPAS1 and renal cell carcinoma.