FDA approves Exelixis' cabozantinib for thyroid cancer

WASHINGTON (Reuters) - The U.S. Food and Drug Administration on Thursday approved Exelixis Inc's cabozantinib as a treatment for medullary thyroid cancer that has spread to other parts of the body.

Cabozantinib, the company's lead product candidate, is an oral drug designed to limit blood supply to tumors as well as block two segments of a pathway used by cancer cells to grow and spread.

The FDA announcement came shortly after the close of stock market trading in New York, where Exelixis shares eased slightly on the day at $5.24 per share.

The regulatory agency noted that cabozantinib is the second drug approved to treat medullary thyroid cancer in the past two years. The other drug, Caprelsa, is marketed by AstraZeneca Pharmaceuticals.

Medullary thyroid cancer, which is rare and difficult to treat, develops in cells that make a hormone called calcitonin, which helps maintain a healthy level of calcium in the blood. It can occur spontaneously or in families that are genetically prone.

The National Cancer Institute estimates that 56,460 Americans will be diagnosed with thyroid cancer and 1,780 will die from the disease in 2012. About 4 percent of thyroid cancers are medullary thyroid cancer.

The FDA completed its review of cabozantinib in six months under the agency's priority review program.

San Francisco-based Exelixis is also studying the drug as a treatment for a number of different tumor types, including prostate cancer.

(Reporting by David Morgan; Editing by Gary Hill and Marguerita Choy)