Addition of VX-661 to KALYDECO® (ivacaftor) Improves Lung Function in People with CF Who Are Heterozygous for the F508del and G551D Mutations in 28-day Phase 2 Proof-of-Concept Study

In Press Release by Cameron

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  • Data provide proof-of-concept for use of VX-661 to further enhance CFTR function in people taking KALYDECO who have the F508del mutation and another mutation known to respond to KALYDECO alone

  • Statistically significant improvements in lung function, as well as decreases in sweat chloride, observed through 28 days of treatment with VX-661 and KALYDECO

May 1, 2014

Vertex Pharmaceuticals Incorporated today announced that treatment with the combination of VX-661 and KALYDECO® (ivacaftor) in a 28-day Phase 2 study showed statistically significant improvements in lung function (FEV1) in people with both the F508del mutation and G551D mutation who were already taking KALYDECO. VX-661 was added to patients’ ongoing KALYDECO treatment for four weeks to evaluate the safety of the combination regimen as well as the effect on lung function, sweat chloride and other measures. In addition to improvements in FEV1, the addition of VX-661 also resulted in decreases in sweat chloride through the 28-day treatment period. Treatment with a combination of KALYDECO and VX-661 for 28 days resulted in a mean within-group absolute improvement in lung function of 4.6 percentage points (p=0.012), a mean within-group relative improvement in lung function of 7.3% (p=0.012) and a mean reduction in sweat chloride of -7.02 mmol/L (p=0.053) through the end of treatment. Following the 28-day treatment period, lung function and sweat chloride levels returned toward baseline. VX-661 was generally well-tolerated when dosed in combination with KALYDECO, and all 18 patients completed the 28-day treatment period.

This is the first proof-of-concept clinical study of a combination of a CFTR corrector (VX-661) and KALYDECO in people with CF heterozygous for the F508del mutation and a mutation, such as G551D, known to be responsive to KALYDECO. The study was conducted following in vitro observations that showed the addition of VX-661 to KALYDECO further enhanced CFTR function in human bronchial epithelial (HBE) cells heterozygous for the F508del and G551D mutations. The clinical results announced today demonstrated the potential for a combination of VX-661 and KALYDECO to further enhance the benefit of treatment with KALYDECO alone in people with the F508del mutation and a mutation known to respond to KALYDECO.

“Consistent with observations from in vitro studies, these results provide an important proof-of-concept for the use of VX-661 in combination with KALYDECO to provide the potential for further benefit in people already being treated with KALYDECO alone who have one F508del mutation and another mutation known to respond to KALYDECO alone,” said Jeffrey Chodakewitz, M.D., Senior Vice President and Chief Medical Officer at Vertex. “While this study was small and evaluated the combination regimen for only four weeks, it provided important scientific evidence that we continue to make progress toward our goal of helping more people with CF and enhancing the benefit our medicines may provide. We look forward to further evaluation of this regimen to better understand the role that VX-661 and KALYDECO may play in the treatment of people with CF.”

About the Study

Patients in this randomized, double-blind study must have received KALYDECO for at least four weeks prior to entering the study. Patients in the study were ages 12 and older and had received KALYDECO for an average of approximately one year. Patients received VX-661, or placebo, in combination with their ongoing KALYDECO treatment for four weeks. To measure both the on-treatment and off-treatment effect of VX-661 in combination with KALYDECO, observations were made at baseline (Day 0), every week during the treatment period (Day 0 – 28) and at multiple timepoints in the four-week period after the completion of treatment (Day 28 – 56). Eighteen patients enrolled in the study, and 14 of these patients received VX-661 (100 mg once daily) in addition to their ongoing treatment with KALYDECO (150 mg q12h). The remaining four patients received placebo and KALYDECO to ensure the study was blinded.

The primary endpoints of the study were safety, tolerability and change in sweat chloride. Change in lung function (percent predicted forced expiratory volume in one second; PPFEV1) was measured as a secondary endpoint.

See the full release here.