Cabozantinib Series

Cabozantinib was approved in November 2012 for the treatment of patients with progressive, unresectable, locally advanced, or metastatic medullary thyroid cancer (MTC). Cabozantinib was granted orphan drug status by the FDA to facilitate development of newtreatment options for patients with MTC. It is a member of a class of tyrosine kinase inhibitors (TKIs) with nanomolar pan-inhibitory activity against VEGFR2, MET, and RET among others. Inhibition of the VEGF pathway has been shown preclinically to initially slow tumor growth, but rapid revascularization is followed by aggressive tumor growth. The MET pathway has been implicated in the development of VEGF resistance, so dual VEGF/MET activity is viewed as desirable. In addition, mutations in RET play a particular role in MTC, with 25% of the tumors inheriting a germlinemutation in the proto-oncogene, so multiple tyrosine kinase inhibition may be viewed as particularly beneficial for the treatment of MTC.