Acting three months before its scheduled decision date, the Food and Drug Administration yesterday approved a drug developed by Vertex Pharmaceuticals Inc. to treat some patients suffering from cystic fibrosis, a rare and often fatal genetic disease.
The drug, called Kalydeco, is the second therapy from the Cambridge company to receive the FDA’s blessing in the past eight months. Its first drug, Incivek, was approved last May to combat the hepatitis C virus.
While other cystic fibrosis drugs already are on the market, they only treat symptoms of the inherited disease, which causes mucus to thicken and block the passage of air to the lungs, making it harder for patients to breathe and digest food. About half of those born with cystic fibrosis don’t live past 38, according to the Cystic Fibrosis Foundation.
Kalydeco, which initially had an FDA decision date of April 18, targets the cause of the disease in roughly 4 percent of the US patient population of 30,000. Those patients have a genetic mutation in a particular protein that sits at the surface of cells and regulates the flow of water and salt. The Vertex drug binds to the protein and works to restores its normal function, helping patients make mucus that lets them absorb and digest food and gain weight.
“This validates our [business] model,’’ said Jeffrey Leiden, who takes over today as Vertex chief executive. “We want to develop breakthrough medicines that really make a difference for patients, and to make sure patients who are eligible can get them.’’
Shares of Vertex climbed 6.3 percent yesterday to close at $36.95 on the Nasdaq exchange as analysts calculated a new revenue stream from a pill that will be priced at $294,000 per patient annually, mostly covered by insurance.
In a note to investors, Mark Schoenebaum, biotechnology analyst for ISI Group in New York, estimated that Kalydeco could be used by 80 percent of the approximately 1,200 people who suffer from the form of cystic fibrosis it treats. But he said the drug could be the first of several from Vertex that will treat ever larger shares of cystic fibrosis patients.
Kalydeco’s approval marked the second time in as many days that the FDA signed off early on new drugs from Massachusetts biotechnology companies. On Monday, the agency approved Erivedge, a capsule codeveloped by Lexington’s Curis Inc. that will be the first treatment for advanced cases of basal cell carcinoma.
Vertex will begin shipping Kalydeco to US wholesalers and pharmacies this week. The company is seeking approval for its use in Europe and expects a decision in the second half of this year. Leiden said Vertex should see a significant increase in its workforce in 2012, though he would not specify a number. It now has about 2,000 employees worldwide, including 1,375 in Massachusetts.
Dr. Ahmet Uluer, director of the adult cystic fibrosis program at Brigham and Women’s Hospital and Children’s Hospital Boston, who was principal investigator at Kalydeco clinical trials, said “we were all caught off guard’’ by its approval yesterday.
“It’s definitely a shift in the way we treat patients with cystic fibrosis,’’ Uluer said. “This is the first time we’ve been able to treat the underlying defect. With this one pill, we’ll be able to restore 30 to 40 percent of the protein function for these patients.’’
FDA officials completed their assessment of Kalydeco in just three months under a expedited program that uses a six-month priority review - rather than the standard 10 months - for drugs that promise significant advances over existing treatments.
Kalydeco was designated an orphan drug, meaning it is for treatment of a disease that affects fewer than 200,000 people nationwide.
“In my 20 years in the industry, I’ve never seen an approval come so rapidly,’’ said Vertex’s Leiden. “It’s a testament to the tremendous innovation and value of the drug.’’
FDA Commissioner Margaret A. Hamburg said in a statement that “Kalydeco is an excellent example of the promise of personalized medicine - targeted drugs that treat patients with a specific genetic makeup.’’
Leiden said the approval of Kalydeco, which is for patients age 6 and older, is just the beginning of a broader push by Vertex to battle cystic fibrosis.
The company is beginning a set of studies aimed at patients aged 2 to 5 and will then turn its attention to a separate genetic mutation that affects another 4 percent of the patient population.
Ultimately, he said, Vertex hopes to combine Kalydeco with so-called corrector medicines that will enable it to treat as much as 70 percent of the patient population.
Under an assistance program, Vertex will provide copay support up to $88,200 a year for some patients with commercial insurance, and will give the drug free to some uninsured patients with household annual incomes below $150,000.
Massachusetts law prevents drug makers from providing copay assistance, though patients here may get help through nonprofit foundations.