The U.S. Food and Drug Administration today approved Cometriq (cabozantinib) to treat medullary thyroid cancer that has spread to other parts of the body (metastasized).

Medullary thyroid cancer develops in cells in the thyroid gland that make a hormone called calcitonin, which helps maintain a healthy level of calcium in the blood. This type of cancer may occur spontaneously or in families with certain genetic mutations that result in one or more cancers of the endocrine system, including the thyroid gland.

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, making it one of the rarer types of thyroid cancers.

“Cometriq is the second drug approved to treat medullary thyroid cancer in the past two years and reflects FDA’s commitment to the development and approval of drugs for treating rare diseases,” said Richard Pazdur, M.D., director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research. “Prior to today’s approval and the approval of Caprelsa in April 2011, patients with this rare and difficult to treat disease had limited therapeutic treatment options.”

The FDA completed review of Cometriq’s application in six months under the agency’s priority review program. This program provides for an expedited six-month review for drugs that may offer major advances in treatment or that provide a treatment when no adequate therapy exists. Cometriq also received orphan-product designation by the FDA because it is intended to treat a rare disease or condition.

Cometriq is a kinase inhibitor that blocks abnormal kinase proteins involved in the development and growth of medullary cancer cells. Patients should not eat for at least 2 hours before and 1 hour after taking Cometriq.

The safety and effectiveness of Cometriq were established in a clinical study involving 330 patients with medullary thyroid cancer. Treatment with Cometriq increased the length of time a patient lived without the cancer progressing (progression-free survival) and, in some patients, reduced the size of tumors (response rate).

Patients who were given Cometriq lived an average of 11.2 months without tumor growth compared with an average of four months in patients receiving a sugar pill (placebo). Results also showed that 27 percent of patients treated with Cometriq had reductions in tumor size lasting an average of nearly 15 months, while patients who received a placebo saw no reductions. Treatment with Cometriq did not extend patients’ lives.

The prescribing information for Cometriq includes a Boxed Warning alerting patients and health care professionals that severe and fatal bleeding and holes (perforations and fistula) in the colon occurred in some patients.

The most common side effects were diarrhea; inflammation or sores of the mouth; redness, pain, or swelling of the digits (hand-foot syndrome); weight loss; loss of appetite; nausea; fatigue; oral pain; graying or loss of hair color; bad taste; new or worsening high blood pressure; abdominal pain and constipation. The most common laboratory abnormalities included increases in liver enzymes, low calcium and phosphorus, decreased white blood cells and platelets.

Cometriq is marketed by Exelixis, based in South San Francisco, Calif. Caprelsa (vandetanib) is marketed by Wilmington, Del.-based AstraZeneca Pharmaceuticals.

Source: FDA.