British pharmaceutical giant AstraZeneca Plc said the U.S. Food and Drug Administration (FDA) cleared its orphan drug vandetanib to treat advanced cases of a thyroid cancer.

The company said vandetanib is first drug approved for medullary thyroid cancer that involves specific types of cells that are found in the thyroid gland and can occur spontaneously, or be part of a genetic syndrome.

About 44,600 new thyroid cancer cases were diagnosed in the United States during 2010, and about 1,690 people died from the disease, according to the National Cancer Institute.

Medullary thyroid cancer is estimated to represent 3 percent to 5 percent of all thyroid cancer; its estimated incidence in the United States for 2010 is about 1,300 to 2,200 patients, making it one of the rarer forms 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 US, said Howard Hutchinson, Chief Medical Officer, AstraZeneca.

The approval of vandetanib is based on the results from a single, randomized international study of 331 patients with late-stage medullary thyroid cancer. Patients in the study were selected to receive vandetanib or placebo (sugar pill).

Patients who received vandetanib had a longer period of time without disease progression when compared to patients receiving placebo, the company said.

AstraZeneca said vandetanib received orphan drug designation in medullary thyroid cancer in 2005. Vandetanib is also under regulatory review in the European Union and Canada.

Shares of AstraZeneca ended Wednesday's trading at 2,912.49 pence on the London Stock Exchange, while ADR's of the company closed at $47.88 on the NYSE.