Vertex Pharmaceuticals Incorporated provided an update on its ongoing Phase 3 development program of its investigational compound VX-661 in combination with ivacaftor, which includes four studies that together are expected to enroll more than 1,000 people with cystic fibrosis (CF). Based on a planned interim futility analysis conducted by the study's independent Data Safety Monitoring Board (DSMB), Vertex plans to stop the study of VX-661 and ivacaftor in people with one copy of the F508del mutation and one copy of a mutation that results in minimal CFTR protein function (F508del het/min).