The VX-661 Phase 3 program includes four Phase 3 studies in multiple different groups of people with CF who have at least one copy of the F508del mutation. The studies are evaluating VX-661 dosed as 100 mg once daily (QD) in combination with ivacaftor dosed as 150 mg every 12 hours (q12h). These studies include people with CF with the following mutations:
- Two Copies of the F508del Mutation: In August, Vertex completed enrollment in a study evaluating 24 weeks of treatment with VX-661 in combination with ivacaftor in approximately 500 people with CF who have two copies of the F508del mutation. Data from this study are expected in the first half of 2017.
- One Copy of the F508del Mutation and a Second Mutation that Results in Residual CFTR Function: In September, Vertex expects to complete enrollment in a study evaluating VX-661 in combination with ivacaftor in approximately 200 people with residual function mutations. The crossover study includes two 8-week dosing periods, separated by an 8-week washout period. The study includes an arm of ivacaftor monotherapy, in addition to an arm evaluating VX-661 in combination with ivacaftor and a placebo arm. Data from this study are expected in the first half of 2017.
- One Copy of the F508del Mutation and a Second Mutation that Results in a Gating Defect in the CFTR Protein: Enrollment is ongoing in a study designed to evaluate VX-661 in combination with ivacaftor in people with gating mutations that have been shown to be responsive to ivacaftor alone. The study is expected to enroll approximately 200 patients and is evaluating 8 weeks of treatment with VX-661 in combination with ivacaftor. Enrollment is expected to complete in late 2016 or early 2017.
- One Copy of the F508del Mutation and a Second Mutation that Results in Minimal CFTR Function: In April, Vertex completed enrollment of approximately 150 people in Part A of a two-part study evaluating people with mutations that result in minimal CFTR function. A planned interim futility analysis was conducted by the study's independent DSMB after at least 8 weeks of dosing to determine whether to stop the study or to continue the study and initiate enrollment in Part B. The analysis showed that the combination of VX-661 and ivacaftor did not result in a pre-specified improvement in lung function. The DSMB recommended that Vertex stop the study and not initiate enrollment in Part B. There were no safety concerns noted in the DSMB's review of the data. Vertex plans to close this study based on the recommendation of the DSMB, and patients from Part A of the study who enrolled in the long-term extension study will be transitioned off the combination of VX-661 and ivacaftor.
