Targeted therapy for thyroid cancer

Researchers have begun to develop newer drugs that specifically target the changes inside cells that cause them to become cancerous. Unlike standard chemotherapy drugs, which work by attacking rapidly growing cells in general (including cancer cells), these drugs attack one or more specific targets on cancer cells.

Targeted drugs for medullary thyroid cancer

Doctors have been especially interested in finding targeted drugs to treat medullary thyroid cancer (MTC) because thyroid hormone-based treatments (including radioactive iodine therapy) are not effective against these cancers.

Vandetanib (Caprelsa^®) is a targeted drug taken as a pill once a day. In patients with advanced MTC, vandetanib stops cancers from growing for an average of about 6 months, although it is not yet clear if it can help people live longer. Some common side effects of vandetanib include diarrhea, rash, nausea, high blood pressure, headache, fatigue, decreased appetite, and belly (abdominal) pain. Rarely, it can also cause serious problems with heart rhythm and infection that can lead to death. Because of its potential side effects, doctors must get special training before they are allowed to prescribe this drug.

Cabozantinib (Cometriq^™) is another targeted drug used to treat MTC. It is taken in pill form once a day. In MTC patients, cabozantinib has been shown to help stop cancers from growing for about 7 months longer than a sugar pill. So far, though, it has not been shown to help patients live longer.

Common side effects include diarrhea, constipation, belly pain, mouth sores, decreased appetite, nausea, weight loss, fatigue, high blood pressure, loss of hair color, and hand-foot syndrome (redness, pain, and swelling of the hands and feet). Rarely, this drug can also cause serious side effects, such as severe bleeding and holes in the intestine.

Several other targeted drugs have shown promising early results against MTC as well. Some of these, such as sorafenib (Nexavar^®) and sunitinib (Sutent^®) are already used to treat other types of cancer. Doctors may try giving these drugs if other treatments, including vandetanib and cabozantinib, aren’t helpful.

Targeted drugs for papillary or follicular thyroid cancer

Fortunately, most of these cancers can be treated effectively with surgery and radioactive iodine therapy, so there is less need for other drugs to treat them. But for cancers in which these treatments aren’t effective, targeted drugs such as sorafenib, sunitinib, pazopanib (Votrient^®), and vandetanib have shown some early promise and may be helpful.