Feb 12 (Reuters) - The U.S. Food and Drug administration on Monday approved a treatment for cystic fibrosis that combines Vertex Pharmaceuticals Inc’s Kalydeco with another medicine, Vertex said, marking the company’s third product for the life-shortening lung disorder.

Vertex shares rose about 2 percent to $154.92 in extended trading after the approval was announced about two weeks ahead of an expected FDA action date.

The treatment, which will be sold under the brand name Symdeko, adds the new drug tezacaftor to previously approved Kalydeco (ivacaftor) and is expected to form the backbone of eventual triple combinations that could treat up to 90 percent of patients with the disease that leads to serious lung infections and deteriorating lung function.

The current medicines can help about 45 percent of the CF population.

Vertex last month released impressive data from clinical trials of two proposed triple combinations showing highly statistically significant improvements in volume of air exhaled in a standard lung function test.

The company said it will begin shipping Symdeko to pharmacies this week. Vertex’s treatments, Kalydeco, Orkambi and now Symdeko, all address the underlying cause of cystic fibrosis, rather than just symptoms.

“Symdeko is an important treatment option for patients who either never started or discontinued Orkambi, and it also provides increased benefit over Kalydeco alone,” Dr. Patrick Flume, director of the Medical University of South Carolina Cystic Fibrosis Center, said in a statement.

Symdeko was approved for CF patients aged 12 and older who have two copies of the F508del gene mutation or who have at least one mutation that is responsive to tezacaftor/ivacaftor.

Vertex said it expects European approval of the two-drug combination in the second half of this year. (Reporting by Bill Berkrot; Editing by Tom Brown)