PD1-3 - Molecular Targeted Treatment for Thyroid Cancer

Abstract

The annual incidence of thyroid cancer is over ten thousand and it has doubled during past two decades in Japan. Differentiated thyroid cancer (DTC, papillary or follicular thyroid cancer) comprises more than 90% of thyroid cancer. The prognosis of DTC is generally favorable, however, once patients with DTC develop resistance to radioactive iodine therapy (RAI), median survival of these patients is around 3 years. Moreover, there had been no effective treatment for RAI refractory DTC until sorafenib showed significant improvement in progression free survival (PFS) comparing with placebo.Vascular endothelial growth factor (VEGF) plays a critical role in tumor angiogenesis and is associated with tumor aggressiveness and metastasis in thyroid cancer. Sorafenib is a multi-targeted tyrosine kinase inhibitor (TKI) that mainly inhibits VEGF receptors and showed significant benefit for RAI refractory DTC. And multi-targeted TKIs other than sorafenib are also under investigation. One of the problems of these new treatment options is the timing for introduction of the treatment. In the DECISION trial, PFS in placebo arm was 5.8 months and about 30% of the patients in placebo arm achieved disease control more than 6 months. These data showed RAI refractory DTC still has indolent nature and may include favorable subset. So I would like to discuss appropriate timing and patients in starting sorafenib.