pazopanib_NCRCC,Ph2 STUDY

Recent advances in understanding the biology and genetics of renal cell carcinoma (RCC) have led to major therapeutic implications. Von Hippel-Lindau (VHL) gene inactivation, present in the majority of sporadic forms of RCC, leads to a defective VHL protein, followed by an active transcription of hypoxia-inducible genes, including vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), c-kit, and others. However, the concept of VHL inactivation in RCC and the subsequent malignant phenotype is almost exclusively seen in patients with clear cell histology. The data about efficacy of VEGF receptor inhibitors for non-clear cell RCC (NCRCC) is rare until now. Recently, however, sunitinib and sorafenib showed its worth for NCRCC in extended access programs.1-3 Although it is not certain, the underlying mechanism of their action might lie in that papillary, chromophobe, and sarcomatoid type overexpress c-kit, which is also a target of both drugs and could therefore provide a therapeutic target for non-clear cell subtypes.4-7 Pazopanib is also a potent and selective, orally available, small molecule inhibitor of VEGFR-1,-2, and -3, PDGF-α, PDGF-β, and c-kit tyrosine kinases. It has been validated and licensed for advanced clear cell RCC (CCRCC).8 However, there is very few data about its efficacy for NCRCC. In this study, we try to evaluate the efficacy of pazopanib in metastatic NCRCC.