Axitinib: The evidence of its potential in the treatment of advanced thyroid cancer

INTRODUCTION: Thyroid cancer is a rare disease with an incidence of around 37,000 cases per year. However, its incidence is rising faster than many other cancers and for men this disease ranks highest overall in the rate of increase (2.4% annual increase) in cancer deaths. As the number of radioactive iodine-resistant thyroid cancers increases, the need for newer treatments has become more important. Axitinib is one of many new small molecule inhibitors of growth factor receptors that have shown promise in the treatment of many cancers. It targets the vascular endothelial growth factor receptors 1, 2 and 3. AIMS: The goal of this article is to review the published evidence for the use of axitinib in the treatment of thyroid cancer and define its therapeutic potential. EVIDENCE REVIEW: The major evidence of axitinib activity has appeared in meeting report abstracts. One phase II study has been published. This included patients with any histological type of thyroid cancer that was not amenable to treatment with radioactive iodine. CLINICAL POTENTIAL: To date, in phase II clinical studies axitinib has demonstrated antitumor activity in advanced refractory thyroid cancer. As a monotherapy it resulted in a 30% response rate with another 38% of patients having stable disease. Axitinib appears to have a good tolerability profile, with hypertension being the most common grade 3 or greater side effect.