PTC Therapeutics, Inc. (NASDAQ:PTCT) shares were performing poorly Thursday as the company unveiled the results of a study.

Research on the pharmaceutical company’s cystic fibrosis study and it did not achieve its primary or secondary endpoints. The medication itself is called ataluren, which was designed to help treat the ailment.

Due to the failure to reach these endpoints, PTC Therapeutics will be shutting down the treatment, closing down its extension studies and pulling back its market application in Europe.

CEO Stuart Peltz, Ph.D., says, “We are disappointed with the outcome of this trial as there are no treatments that target the underlying cause of nonsense mutation cystic fibrosis, one of the most difficult forms to treat.”

He added that the company was grateful to patients and investigators who formed part of its trial, and the company will further examine ataluren and its potential applications.

PTC Therapeutics is also working on a treatment called translarna, which is a protein restoration therapy that is designed to help patients by enabling the formation of a functioning protein in patients who have a series of nonsense mutation-caused genetic disorders.

In Europe, the medication has received approval from regulators and it is currently in place to help treat Duchenne muscular dystrophy.

PTCT stock took quite a hit Thursday, falling more than 15.6%.