Pazopanib is an oral inhibitor of angiogenesis that inhibits VEGFR, PDGFR & c-KIT activity. A prospective randomized trial comparing pazopanib with placebo in patients with untreated metastatic kidney cancer and after cytokine therapy, respectively, showed a significant improvement in progression-free survival and tumor response in the former (9.2 months vs. 4.2 months). This trial suggests that pazopanib may be a first-line dosing option for patients with metastatic kidney cancer. However, pazopanib is recommended as a second option for first-line treatment due to the small number of patients included in the initial phase III trial compared to phase III clinical studies of other targeted agents. More recently, a phase III non-inferiority randomized trial (COMPARZ) showed no significant difference in treatment efficacy between pazopanib and sunitinib, with the difference being in the toxic effects of the two drugs, with pazopanib appearing to have milder side effects and better treatment tolerability for patients than sunitinib. Therefore, the COMPARZ study established pazopanib as first-line treatment for metastatic kidney cancer.