Pazopanib is a second-generation multitargeted tyrosine kinase inhibitor against vascular endothelial growth factor receptor-1, -2, and -3, platelet-derived growth factor receptor-alpha, platelet-derived growth factor receptor-beta, and c-kit. These receptor targets are part of the angiogenesis pathway that facilitates the formation of tumour blood vessel for tumour survival and growth.
Pazopanib is a synthetic indazolylpyrimidine and reaches steady state concentrations of >15 μg/ml. This concentration is high enough to observe maximal inhibition of VEGFR2 phosphorylation and some anti-tumour activity (concentration required to inhibit receptors is 0.01 - 0.084 μmol/L). A reduction in tumour blood flow, increased tumour apoptosis, inhibition of tumour growth, reduction in tumour interstitial fluid pressure, and hypoxia in cancer cells can be observed in patients receiving treatment.
Metabolized by CYP3A4 and to a lesser extent by CYP1A2 and CYP2C8. Metabolites are less active than pazopanib (10 to 20-fold less active). Three of its metabolites can be observed in the systemic and account for <10% of plasma radioactivity.