FDA approves Vertex's cystic fibrosis drug WASHINGTON (Reuters) - Regulators approved Vertex Pharmaceuticals' Kalydeco, the first drug designed to treat the underlying cause of cystic fibrosis. The Food and Drug Administration said on Tuesday Kalydeco was effective in treating people with the genetic disease, which impairs the lungs and digestive system. Vertex shares shot up 9 percent to $37.80 on Nasdaq after the announcement. Cystic fibrosis affects about 30,000 people in the United States. Kalydeco, or VX-770, targets a defective protein that causes cystic fibrosis in about 4 percent of patients. Reporting by Anna Yukhananov; Editing by Derek Caney