Shares of Vertex Pharmaceuticals Inc. soared more than 50 percent in premarket trading Tuesday after the drugmaker said its treatment for cystic fibrosis appeared to work better than a placebo in a late-stage study.

Cystic fibrosis is a rare inherited disease that causes thick mucus to form in the lungs and other organs. Vertex said its treatment helped improve lung function for the people over 12 years old with the most common form of the disease who took part in the study. The treatment was a combination of the drugs lumacaftor and ivacaftor. More than 1,100 people took part in the study.

Because of the results, Vertex plans to seek approval for the treatment in the U.S. and Europe.

The Boston company currently makes and sells two other drugs: one is another cystic fibrosis treatment and the other is for people with hepatitis C.

Vertex shares jumped 56 percent to $103.75 in trading before the market open Tuesday. If those gains hold after the market opens, it will be an all-time high for the stock.