F.D.A. Approves New Cystic Fibrosis Drug

The first drug that treats an underlying cause of cystic fibrosis, rather than just the symptoms, was approved by the Food and Drug Administration on Tuesday, more than 22 years after the gene responsible for the disease was first identified.

The drug, called Kalydeco and developed by Vertex Pharmaceuticals, counters the effect of one specific mutation in the gene that accounts for 4 percent — or about 1,200 — cystic fibrosis cases in the United States.

“This is a breakthrough therapy for the cystic fibrosis community because current therapies only treat the symptoms of this genetic disease,” Dr. Janet Woodcock, the director of the Center for Drug Evaluation and Research at the F.D.A., said in a statement issued by the agency.

The F.D.A.’s approval, while expected, came nearly three months before its deadline. The drug is approved for patients age 6 and older with the G551D mutation.

Kalydeco, known generically as ivacaftor and during its development as VX-770, will cost $294,000 a year, a price roughly in line with those of some other drugs for extremely rare diseases. Vertex said it would have various programs to help patients pay for the drugs or obtain them free.

At such a price, sales of the drug could reach hundreds of millions of dollars a year, even with so few patients.

About 30,000 Americans have cystic fibrosis, which is caused by mutations in a gene called CFTR that is responsible for transport of chloride ions across cell membranes. People with the disease tend to have thick mucus in the lungs, which leads to infections and lung damage. Their average life span is 37 years.

The F.D.A. said it based its approval on two placebo-controlled studies involving a combined 213 patients that showed “significant and sustained improvement in lung function.”

Dr. Ahmet Uluer, a pulmonologist at Children’s Hospital of Boston, said that some of his patients in the clinical trials experienced “a significant change in their day-to-day lives,” including a patient who was able to shovel snow for the first time. But he said the drug was not likely to reverse years of accumulated lung damage.

The story behind Kalydeco is a cautionary tale for those who believe the sequencing of the human genome will lead to a bonanza of new drugs. While the gene responsible for cystic fibrosis was identified in 1989, it took many years to figure out exactly how mutations led to the disease and even longer to figure out how to counteract the mutations.

“There are all these different mutations and each of the mutations was causing it to be broken in a different way,” said Eric Olson, vice president for the cystic fibrosis program at Vertex, which is based in Cambridge, Mass.

Attempts at treating the disease using gene therapy — putting correct copies of the gene into the lungs — did not work. But in the 1990s, techniques were developed to screen chemicals to see if they affected ion transport.

The Cystic Fibrosis Foundation contributed $75 million to Vertex for research, an example of how patient advocacy groups have been taking a more direct role in drug development, in what is often called “venture philanthropy.”

Robert J. Beall, president of the foundation, said the money it had given to Vertex and other companies lowered the risk for drug companies to develop products for a rare disease. “We get their attention,” he said. “We’re at the table with them.”

The foundation will earn royalties from sales of Kalydeco, money that will be put into further research.

Vertex has two other drugs in midstage clinical trials that it hopes will help cystic fibrosis patients with the most common mutation.

Kalydeco is the second drug from Vertex to be approved by the F.D.A. in the last year.

Its drug for hepatitis C, Incivek, approved in May, is on pace to exceed $1 billion in sales in its first 12 months on the market because it increases the cure rate of that disease and shortens treatment time for many patients.

Yet analysts and investors are already assuming that Incivek will be overtaken in a few years by other drugs. So their attention has turned to Kalydeco.

Vertex shares rose 6.36 percent, to $36.95 on Tuesday.

This article has been revised to reflect the following correction:

An earlier version of this article misidentified the mutation for which the drug is approved. It is the G551D mutation, not F551D.

###

By ANDREW POLLACK