The therapeutic potential of HIF-2 antagonism in renal cell carcinoma

Hypoxia, the insufficient delivery of oxygen for the demand of a tissue, contributes to the development of an aggressive phenotype, resistance to radiation therapy and chemotherapy, and is predictive of a poor outcome in numerous tumor types. Adaptation to hypoxia is mediated by hypoxiainducible factors (HIFs), including HIF-1a and HIF-2a, which regulate genes promoting angiogenesis, increased tumor growth or metastasis. In kidney cancer, HIF-2a is believed to be the most important driver for development and progression of clear cell renal cell carcinoma (ccRCC), highlighting the therapeutic potential of HIF-2 antagonists in this disease. Recent studies show that HIF-2a can be targeted by selective, and orally active new class of inhibitors. In conjunction with the restricted expression of HIF-2a in normal adult physiology, these studies suggest that such therapeutic approach might be favorable for patients with lower toxicity than current anti-angiogenic drugs like sunitinib. However, the differential sensitivity to these HIF-2a antagonists along with the potential mechanisms of resistance reported in these studies advocate for the identification of biomarkers to determine which patients are more likely to benefit from these therapies as well as paving the way for second generation inhibitors or complementary inhibitory approaches.