Vandetanib (100 mg) in Patients with Locally Advanced or Metastatic Hereditary Medullary Thyroid Cancer

Purpose: Vandetanib is a once-daily oral inhibitor of vascular endothelial growth factor receptor-2 and epidermal growth factor receptor tyrosine kinases that also inhibits rearranged during transfection kinase activity. Vandetanib (300 mg/d) has previously demonstrated antitumor activity in patients with advanced hereditary medullary thyroid cancer (MTC). This study investigated the efficacy and safety of 100 mg/d vandetanib in patients with advanced hereditary MTC. Patients and Methods: Eligible patients with unresectable, measurable, locally advanced, or metastatic hereditary MTC received 100 mg/d vandetanib. Upon disease progression, eligible patients could enter postprogression treatment with 300 mg/d vandetanib until a withdrawal criterion was met. The primary objective was to assess the objective response rate by response evaluation criteria in solid tumors. Results: The study comprised 19 patients (13 males, six females; mean age 45 yr). Confirmed objective partial responses were observed in three patients, yielding an objective response rate of 16% (95% confidence interval 3.4-39.6). Stable disease lasting 24 wk or longer was reported in a further 10 patients(53%); the disease control rate was therefore 68%(95% confidence interval 43.4-87.4). Serum levels of calcitonin and carcinoembryonic antigen showed a sustained 50% or greater decrease from baseline in 16% (three of 19) and 5% (one of 19) of patients, respectively. Adverse events were predominantly grade 1 or 2 and consistent with previous vandetanib monotherapy studies. Conclusions: Vandetanib at a once-daily dose of 100 mg has clinically relevant antitumor activity in patients with locally advanced or metastatic hereditary MTC and an overall acceptable safety profile. (J Clin Endocrinol Metab 95: 2664-2671, 2010)