FDA approves drug to treat aggressive medullary thyroid cancer

After an international, double-blind clinical trial conducted among patients with advanced medullary thyroid cancer, the U.S. Food and Drug Administration (FDA) recently approved a medication called vandetanib to treat the disease.

The drug is part of a class of prescription treatments called tyrosine kinase inhibitors, which target an enzyme that controls the rate of thyroid cellular growth. Mutations in tyrosine kinases can result in their overactivity, allowing thyroid tissue to grow without restraint.

In the clinical trial, more than 230 individuals with late-stage medullary thyroid cancer were given 300 milligrams of vandetanib daily. All participants had nonresectable tumors, meaning the cancer was advanced or entrenched enough to preclude the possibility of surgical removal.

Those who took vandetanib experienced improvements in progression-free survival, living longer beyond treatment without any additional growth of the medullary thyroid tumor. The median survival time among participants who took the medication was more than 22 months.

Overall, 44 percent of those taking the medication responded to it, compared to 1 percent of those taking a placebo.

Medullary carcinomas are a relatively rare form of thyroid disease, accounting for between 2 and 3 percent of all cancers of the thyroid gland, according to the National Cancer Institute (NCI).

This form of thyroid cancer starts in the parafollicular calcitonin-secreting cells, which are the first to experience excess growth in this category of thyroid cancer. People who have thyroid surgery for early parafollicular hyperplasia, the precursor to medullary thyroid cancer, have a survival rate of 100 percent, according to the Columbia University Department of Surgery.

However, once a medullary thyroid carcinoma metastasizes, the rate of survival drops significantly. The NCI estimates that 83 percent of patients with the condition survive five years beyond their initial diagnoses, compared to the 90 and 94 percent survival rates for the more common papillary and follicular varieties.

The FDA states that between 1,300 and 2,200 Americans are diagnosed with medullary thyroid cancer each year.