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Drug trial results push Vertex shares up 60 percent

Investors bid up shares of Vertex Pharmaceuticals Inc. to a record high Friday after the Cambridge biotechnology company released clinical trial data late Thursday that appeared to dramatically improve the prospects of its plan to build a portfolio of cystic fibrosis drugs.

The treatments, only one of which is currently approved for sale, could help up to 30,000 people in the United States and 70,000 globally who suffer from the inherited disease.

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Cystic fibrosis 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 the condition do not live past age 38, the Cystic Fibrosis Foundation said.

Vertex stock, which surged in after-market trading Thursday, closed up 61.4 percent at $85.36 a share Friday, a gain of $32.49 on the Nasdaq .

Analysts said the encouraging results of a Vertex midstage clinical trial could be read as a vote of confidence for its approach of combining its approved cystic fibrosis drug Kalydeco with experimental therapies to treat subsets of patients.

“In our opinion, the data were solid and provide proof of concept,” biotechnology analyst Phil Nadeau, managing director at investment bank Cowen & Co., told investors.

Nonetheless, the combined treatments being tested still must succeed in late-stage clinical trials with longer durations and larger patient bases, Nadeau cautioned. The chances of FDA approval have risen, he said, but only about 50 percent.

The company’s first cystic fibrosis drug, Kalydeco, approved in February 2012, targets the cause of the disease in about 4 percent of the US patient population. 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 restore its normal function, helping patients make mucus that lets them absorb and digest food and gain weight.

In the midstage trial just concluded, Vertex combined Kalydeco with its drug candidate, called VX-661. That mix “showed statistically significant improvements in lung function” among adult patients with two copies of a common cystic fibrosis regulator gene mutation, according to the company.

“This is really a validation of our strategy,” Vertex spokesman Zachry Barber said Friday.

Robert Weisman can be reached at weisman@globe.com. Follow him on Twitter @GlobeRobW.
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