A phase III study of sorafenib in RAI-resistant differentiated thyroid cancer confirmed PFS of 10.8 months versus placebo, but tumor shrinkage was observed only in 10% of patients.42 Randomized, double-blind, phase II trial of vandetanib, a TKI of RET, VEGFR, and EGFR signaling, in patients with refractory to radioactive iodine therapy demonstrated significant PFS of 11.1 months compared with 5.9 months in the placebo group. This evidence concerns the gene KDR and differentiated thyroid carcinoma.