A HIF-2α inhibitor; inhibits HIF-2α heterodimerization with the ARNT PAS-B domain in a cell-free assay (Ki = 23 nM), activation of HIF-2α in a reporter assay using 786-O renal cell carcinoma cells (IC50 = 17 nM), and secretion of VEGF-A from 786-O cells (EC50 = 17 nM); induces tumor regression in a 786-O mouse xenograft model from 0.3-3 mg/kg; reduces hematocrit levels and right ventricular pressure in mice expressing VHLR200W in a model of Chuvash polycythemia at 0.1 mg/g