Company: Vertex Pharmaceuticals Incorporated

A look at the 10 biggest percentage gainers on Nasdaq at the close of trading:

A look at Nasdaq 10 most-active stocks at the close of trading:

A look at the 10 biggest percentage gainers on Nasdaq at the close of trading:

(Reuters) - Vertex Pharmaceuticals Inc's <VRTX.O> new cystic fibrosis drug Kalydeco, when combined with its experimental treatment for the disease, led to significantly improved breathing ability in a mid-stage study, sending Vertex shares soaring 49 percent.

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(Reuters) - Vertex Pharmaceuticals Inc's <VRTX.O> new cystic fibrosis drug Kalydeco, when combined with its experimental treatment for the disease, led to significant improvement in lung function in a mid-stage study, sending Vertex shares soaring 45 percent.

Vertex Pharmaceuticals' share soared on Monday, after a study  found its new cystic fibrosis drug  leads to improvement in lung function.

Shares of Vertex Pharmaceuticals Inc. soared nearly 50 percent in pre-market trading Monday after the drug developer said it saw better-than-expected results in a mid-stage study of a potential treatment for the most severe form of cystic fibrosis.

(Reuters) - Vertex Pharmaceuticals Inc's <VRTX.O> new cystic fibrosis drug Kalydeco, when combined with its experimental treatment for the disease led to significant improvement in lung function in a mid-stage study, sending Vertex shares soaring 57 percent.

Gilead Sciences shares soared more than 15 percent after an experimental hepatitis C drug acquired by the company when it paid nearly $11 billion to buy Pharmasset produced encouraging results in a closely watched clinical trial, results of which were released in Barcelona.

Gilead Sciences said some patients treated with its experimental hepatitis C drug, which the company acquired with its $11 billion buy of Pharmasset, experienced a relapse of the infection in an ongoing study.