WASHINGTON Children taking Vertex Pharmaceuticals Inc's cystic fibrosis pill may be at risk of getting cataracts, based on a study in juvenile rats, according to a statement Wednesday on the U.S. Food and Drug Administration's website.
The FDA added information about the risk on Wednesday to the label for Kalydeco, the first drug designed to treat the underlying cause of cystic fibrosis, a life-shortening genetic disease that impairs the lungs and digestive system and affects about 30,000 people in the United States.
Shares of the company slipped 1.0 percent to $53.55 in morning trading on Nasdaq.
Rats that were seven to 35 days old developed cataracts after being given a dose of Kalydeco that was about a tenth of the maximum recommended dose for people, the study showed. Cataracts are a clouding of the lens in the eye that can impair vision.
It was uncertain whether the finding in juvenile rats would apply to children, since people and rats have different eye development, the FDA said.
To ascertain the risks to children, the regulator has asked Vertex to conduct a clinical study of the risk of cataracts in kids who are already taking Kalydeco up to 11 years of age, when eye development is generally complete. The children must be followed for at least two years and get eye appointments every six months.
The FDA approved Kalydeco in January for patients from six years of age and older, who have a specific defective protein which causes cystic fibrosis in about 4 percent of patients.
Vertex still plans to expand use of the drug to patients as young as two, and is set to launch a study in that group later this year.
Company spokeswoman Dawn Kalmar said the company had received no complaints about cataracts from about 350 people who took the drug during clinical trials, or from more than 600 people who have been treated with it since January.
Kalydeco is Vertex's second product approved in the United States, after a hepatitis C treatment called Incivek.
(Reporting by Anna Yukhananov in Washington, additional reporting by Esha Dey in Bangalore; Editing by Bernadette Baum)