Vertex’s Kalydeco drug approved for rare form of cystic fibrosis

In a big win for Cambridge-based Vertex Pharmaceuticals, the US Food and Drug Administration today approved the company’s drug Kalydeco (ivacaftor) to treat a rare form of cystic fibrosis. The drug is approved for patients ages 6 and over who carry the G551D gene mutation, and the news follows the approval last year of Vertex’s hepatitis C drug Incivek.

Only 4 percent of the 30,000 cystic fibrosis sufferers in the United States -- about 1,200 people -- are believed to have this mutation, according to the FDA. An estimated 200 of them are under 6 and wouldn’t yet qualify for the drug, according to Vertex.

Vertex executives said in a briefing that they will begin shipping Kalydeco to pharmacies in the United States this week. The company said it plans to charge $94,000 a year for the twice-daily pill and will provide assistance to those without insurance.

Cystic fibrosis occurs from a genetic defect that leads to the formation of thick mucus in the lungs, digestive tract, and other parts of the body, causing breathing difficulties, nutritional deficiencies that result in a lack of weight gain, and other complications such as infections and diabetes. More than half of those with the condition die before age 18 and few live past 40.

“Kalydeco is an excellent example of the promise of personalized medicine – targeted drugs that treat patients with a specific genetic makeup,” FDA Commissioner Dr. Margaret A. Hamburg said in a statement.

The agency based its expedited approval -- which took just three months -- on two clinical studies involving 213 patients aged 11 and over that lasted nearly a year. In both studies, those treated with Kalydeco had improved lung function, increased weight gain, and fewer acute problems that often require hospital visits and treatment with antibiotics, compared with those who took a placebo, according to Vertex.

Still unknown is whether the drug will increase their lifespans.

The most common side effects of Kalydeco include upper respiratory tract infection, headache, stomach ache, rash, diarrhea, and dizziness. The drug may also increase liver enzymes, so the FDA recommends patients have their levels monitored regularly.

Vertex has six other drugs in clinical trials, including ones to treat epilepsy and rheumatoid arthritis.