FDA approves Kalydeco to treat rare form of cystic fibrosis

Breakthrough therapy targets defective protein

The U.S. Food and Drug Administration today approved Kalydeco (ivacaftor) for the treatment of a rare form of cystic fibrosis (CF) in patients ages 6 years and older who have the specific G551D mutation in the Cystic Fibrosis Transmembrane Regulator (CFTR) gene.

CF is a serious genetic disorder affecting the lungs and other organs that ultimately leads to an early death. It is caused by mutations (defects) in a gene that encodes for a protein called CFTR that regulates ion (such as chloride) and water transport in the body. The defect in chloride and water transport results in the formation of thick mucus that builds up in the lungs, digestive tract and other parts of the body leading to severe respiratory and digestive problems, as well as other complications such as infections and diabetes.

CF, which affects about 30,000 people in the United States, is the most common fatal genetic disease in the Caucasian population. About 4 percent of those with CF, or roughly 1,200 people, are believed to have the G551D mutation.

“Kalydeco is an excellent example of the promise of personalized medicine – targeted drugs that treat patients with a specific genetic makeup,” said FDA Commissioner Margaret A. Hamburg, M.D. “The unique and mutually beneficial partnership that led to the approval of Kalydeco serves as a great model for what companies and patient groups can achieve if they collaborate on drug development.”

The FDA reviewed and approved Kalydeco in approximately three months under the agency’s priority review program that is designed to expedite the review of drugs. The priority review program uses a six-month review, instead of the standard 10 months, for drugs that may offer significant advances in treatment over available therapy.

Kalydeco was approved ahead of the drug’s April 18, 2012 prescription user fee goal date and is designated as an orphan drug, which identifies the disease as affecting fewer than 200,000 people in the United States.

In patients with the G551D mutation, Kalydeco, a pill taken two times a day with fat-containing food, helps the protein made by the CFTR gene function better and as a result, improves lung function and other aspects of CF such as increasing weight gain.

“Kalydeco is the first available treatment that targets the defective CFTR protein, which is the underlying cause of cystic fibrosis,” said Janet Woodcock, M.D., director of the FDA’s Center for Drug Evaluation and Research. “This is a breakthrough therapy for the cystic fibrosis community because current therapies only treat the symptoms of this genetic disease.”

Two 48-week, placebo-controlled clinical studies involving 213 patients, one in patients ages 12 years and older and another in patients ages 6 years to 11 years, were used to evaluate the safety and efficacy of Kalydeco in CF patients with the G551D mutation. In both studies, treatment with Kalydeco resulted in significant and sustained improvement in lung function.

Kalydeco is effective only in patients with CF who have the G551D mutation. It is not effective in CF patients with two copies of the F508 mutation in the CFTR gene, which is the most common mutation that results in CF. If a patient’s mutation status is not known, an FDA-cleared CF mutation test should be used to determine whether the G551D mutation is present.

The most common side effects of Kalydeco include upper respiratory tract infection, headache, stomach ache, rash, diarrhea, and dizziness.

Kalydeco is manufactured by Vertex Pharmaceuticals Inc. of Cambridge, Mass.

Source: U.S. FDA