The FDA 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 is caused by mutations in a gene that encodes for a protein called CFTR responsible for regulating ion (such as chloride) and water transport in the body, and ultimately leads to death. 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 was reviewed and approved by the FDA in approximately three months under the agency’s priority review program that is designed to hasten 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.
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. It is the first available treatment that targets the defective CFTR protein, which is the underlying cause of cystic fibrosis.
Two 48-week, placebo-controlled clinical studies involving 213 patients, one in patients ages 12 years and older and another in patients ages 6 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.