Pazopanib: Clinical development of a potent anti-angiogenic drug.

Pazopanib is an oral, multi-targeted, tyrosine kinase inhibitor (TKI) that binds to the vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR) and several other key proteins responsible for angiogenesis, tumor growth and cell survival. Pazopanib exhibited in vivo and in vitro activity against tumor growth and, in early clinical trials, was well tolerated with the main side effects being hypertension, fatigue and gastrointestinal disorders. Pazopanib showed clinical activity in several tumors including renal cell cancer (RCC), breast cancer, soft tissue sarcoma, thyroid cancer, hepatocellular cancer and cervical cancer. A phase III clinical trial in metastatic RCC patients showed a significant improvement in progression-free survival, leading to its approval in the US. In metastatic breast cancer, the combination of pazopanib with lapatinib was more effective than lapatinib alone. At the time of the current publication, pazopanib is being evaluated in more than 35 phase II and III trials.