**4.5 Cabozantinib**

Cabozantinib inhibits Tie-2, c-MET, KIT, VEGFR-1, VEGFR-2, and RET kinases [78]. In a phase I trial, cabozantinib was administered to patients with advanced solid tumors, including 37 patients with advanced medullary thyroid cancer, and was found to have efficacy and a good safety profile in medullary thyroid cancer as it induced tumor shrinkage of >30% in some medullary thyroid cancer patients with measurable disease [79]. Cabozantinib was also evaluated in 15 radioiodine refractory differentiated thyroid cancer patients who had progressed on conventional treatment and had measurable disease [80]. FDA-approved cabozantinib for the treatment of metastatic medullary thyroid cancer. Cabozantinib was also evaluated in patients with advanced radioiodine refractory differentiated thyroid cancer who had already received another VEGFR-targeted treatment and was found to be clinically effective [81]. In a double-blind phase III trial, cabozantinib was found to be effective in improving progression-free survival in patients with progressive medullary thyroid cancer [82].
