Multi-targeted tyrosine kinase inhibitors in clinical development: focus on XL-184 (cabozantinib).

XL-184 (cabozantinib) is a novel, small-molecule, multitargeted receptor tyrosine kinase inhibitor with particular activity against hepatocyte growth factor receptor (tyrosine-protein kinase Met), vascular endothelial growth factor receptor 2 (VEGFR-2) and proto-oncogene tyrosine-protein kinase receptor Ret. There is ample evidence of Met, VEGFR-2 and Ret signaling in several tumor types. Preclinical data suggest that XL-184 has activity in tumors derived from both epithelial and mesenchymal origins. Phase I and II clinical studies support significant antitumor activity, particularly in medullary thyroid cancer and cancers metastatic to the bone. This review will evaluate XL-184's preclinical pharmacology, pharmacokinetics, drug interactions and clinical activity in phase I through phase III studies.