FDA Approves Vandetanib for Medullary Thyroid Cancer
by Nick Mulcahy

April 7, 2011 - The US Food and Drug Administration (FDA) has approved vandetanib (AstraZeneca) for the treatment of symptomatic or progressive medullary thyroid cancer in patients with unresectable locally advanced or metastatic disease. It is the first drug ever approved for the treatment of this rare form of thyroid cancer.

"Vandetanib is the only medicine to receive FDA approval specifically for use in patients with advanced medullary thyroid cancer and is the first treatment that AstraZeneca has developed and brought to market under orphan drug designation in the United States," said Howard Hutchinson, chief medical officer of AstraZeneca, in a press statement.

"Vandetanib's approval underscores FDA's commitment to approving treatments for patients with rare and difficult-to-treat diseases," said Richard Pazdur, MD, director of the Office of Oncology Drug Products in the FDA's Center for Drug Evaluation and Research, in a news release.

Vandetanib targets the ability of medullary thyroid cancer to grow and expand, according to the FDA. The use of vandetanib, a kinase inhibitor that is administered orally on a daily basis, in patients with indolent, asymptomatic, or slowly progressing medullary thyroid cancer "should be carefully considered because of the treatment-related risks," according to AstraZeneca's statement.

There were approximately 44,600 new thyroid cancer cases diagnosed in the United States in 2010, and about 1,690 people died from the disease, according to the National Cancer Institute. Medullary thyroid cancer accounts for an estimated 3% to 5% of all thyroid cancers, or about 1,300 to 2,200 patients in the United States in 2010.

Efficacy and Treatment Risks

The approval of vandetanib is based on the results of the phase 3 ZETA study, which randomized 331 patients with unresectable locally advanced or metastatic medullary thyroid cancer to vandetanib 300 mg (n = 231) or placebo (n = 100).

In the study, patients treated with vandetanib had a median progression-free survival of at least 22.6 months, compared with 16.4 months for patients randomized to placebo (hazard ratio [HR], 0.35; 95% confidence interval [CI], 0.24 to 0.53; P < .0001). "It is too early to determine the median progression-free survival in patients treated with vandetanib or to tell whether they will live longer (overall survival), compared with patients treated with placebo," according to the FDA.

Serious adverse events reported during the study resulted in 5 deaths in patients treated with vandetanib. Causes of death included breathing complications, heart failure, and sepsis. Vandetanib has been shown to affect the electrical activity of the heart, which in some cases can cause irregular heart beats that can be life-threatening.

The prescribing information for vandetanib includes a box warning about treatment-related QT prolongation, Torsades de pointes, and sudden death.

The most common adverse drug reactions (>20%) seen in the ZETA trial with vandetanib were diarrhea (57%), rash (53%), acne (35%), nausea (33%), hypertension (33%), headache (26%), fatigue (24%), decreased appetite (21%), and abdominal pain (21%), according to the company.

A Risk Evaluation and Mitigation Strategy (REMS) is required for vandetanib, and only prescribers and pharmacies that are certified through the vandetanib REMS program will be able to prescribe and dispense vandetanib.

Vandetanib will be dispensed exclusively through the pharmacy business unit of Biologics, Inc., an integrated oncology management company, according to AstraZeneca.

Vandetanib is currently under regulatory review in the European Union and Canada.