Vertex Pharmaceuticals Inc. said final data from a midstage clinical study of an ­experimental combination of its cystic fibrosis drugs “showed statistically significant improvements” in lung function among some adults with cystic fibrosis.

In May, Cambridge-based Vertex issued an “interim ­analysis” on the effects of its ­Kalydeco-VX-809 combination therapy. Kalydeco is the first drug that seeks to target the underlying cause of cystic ­fibrosis. The company’s stock surged on the news. A few weeks later, Vertex revised the interim analysis, saying it overstated the clinical data. Between the initial report and the revision, several executives and directors sold stock worth millions of dollars.

A spokesman said Thursday that final results confirm what May’s revised report said: The combination therapy showed significant improvements in lung function among adults who have two copies of the F508del mutation.