The European Commission granted extended approval for the use of Vertex Pharmaceuticals Inc.'s Kalydeco in treating infants with cystic fibrosis ages 6 months to up to a year, weighing 5 kilogram and more.

The Boston-based biotechnology company's Kalydeco, also known as ivacaftor, was previously indicated for patients aged one year and older and whose cystic fibrosis is positive for at least one of nine cystic fibrosis transmembrane conductance regulator, or CFTR, gene mutations.

The approval is based on an ongoing phase 3 trial, dubbed Arrival, that is evaluating Kalydeco in infants with cystic fibrosis who are younger than the age of two and have one CFTR gene mutation.

Kalydeco's safety profile is consistent with previous late-stage studies, the company added.

The cystic fibrosis treatment is already approved by the U.S. Food and Drug Administration to treat six-month-old infants and toddlers between the ages of one and two.