A small percentage of patients with metastatic (cancerous cells that have spread) differentiated thyroid cancer do not respond to radioactive iodine (RAI) treatment and TSH suppression. In these patients, there is still an option: targeted Tyrosine Kinase Inhibitors (TKIs). TKIs target a group of proteins, called tyrosine kinases, that are involved in the growth and spread of certain cancers. Below are medications approved for use in Canada. Many more are in development.
Lenvima™ (levatinib capsules) is used to treat a type of thyroid cancer that can no longer be treated with RAI. Lenvima™ works by blocking the creation of certain proteins in tumour cells, slowing down the growth of new blood vessels in these tumours. This cuts off the supply of nutrients and oxygen to the tumour, which slows or prevents its growth. Lenvima™ also acts directly on cancer cells in other ways to kill them or slow down their rate of growth.
Caprelsa® (vandetanib tablets) is used to treat medullary thyroid cancer in adult patients whose tumour cannot be removed by surgery or has spread from the thyroid to other parts of the body. Like Lenvima™, Caprelsa® works by blocking the production of certain proteins in tumour cells, which slows down the growth of new blood vessels, cutting off the supply of nutrients and oxygen to the tumour to slow or prevent its growth. Caprelsa® also acts directly on cancer cells to kill them or slow down their rate of growth.