The study being terminated involved patients with one copy of the F508del mutation and one copy of a mutation that results in minimal cystic fibrosis transmembrane conductance regulator (CFTR) protein function (F508del het/min).
The company’s decision was based on the results from a planned interim futility analysis by the independent Data Safety Monitoring Board that showed an insufficient improvement in lung function in the patients.
Three other phase 3 studies involving VX-661 plus ivacaftor will continue.
One study is assessing the drug combination in patients with two copies of the F508del mutation, a second in patients one F508del mutation and one residual function mutation, and a third in patients with one F508del mutation and one mutation that results in a gating defect in the CFTR protein.
Vertex aims to submit a New Drug Application (NDA) to the US Food and Drug Administration for VX-661 in combination with ivacaftor in the second half of 2017, pending data from the Phase 3 program.
The NDA is anticipated to include data from the study in people with minimal function mutations.
CF is caused by a defective or missing CFTR protein resulting from mutations in the CFTR gene. It affects about 75,000 people in North America, Europe and Australia.