RE-POST – Final Data: Phase 2 Combo Study VX-809 & Cystic Fibrosis Drug Kalydeco – 2012 North American CF Conference



Hi all,

Earlier this month at the at the 26th Annual North American CF Conference, final data from a Phase 2 study of a trial involving a treatment with the CF drug compound VX-809 and Kalydeco was discussed by Dr. Michael Boyle of Johns Hopkins School of Medicine. Overall, Dr. Boyle stated that the final results showed statistically significant improvements in lung function for cystic fibrosis patients treated with this potential drug.

The final results from this trial that enrolled 109 people with CF aged 18 years and older with one or two copies of DF508 were based on the last 28 days of the 56-day study were initially released this past June by the manufacturer of Kalydeco, Vertex Pharmaceuticals, Inc. ( Participants were divided into five treatment groups of approximately 20 individuals each. Three groups of those with two copies of DF508 received the experimental drug VX-809 alone for 28 days, then in combination with Kalydeco for an additional 28 days. A group with one copy of DF508 followed the same regime. A placebo group holding both one and two copies of the mutation was also involved in this trial.

The three groups with members who had two copies of DF508, the most common cystic fibrosis gene mutation, were treated with varying doses of VX-809 (200mg, 400mg, 600mg) in combination with Kalydeco. One of the primary endpoints to this study focused on the improvement of lung function, defined as the percent predicted FEV1 (the amount of oxygen that can be forcibly exhaled in one second). These final results showed that the most significant improvement was found with those who received 600mg of VX-809. To quantify this, from day 28 to 56, when patients began to receive Kalydeco in addition to VX-809, as opposed to the first 28 days when the group was dosed only with VX-809, it was revealed that 55% of participants witnessed a greater than 5% improvement in FEV1. Further, from day 28 to 56, 25% of the 600mg group showed a 10% improvement in FEV1.

Patients in this study who hold just one of copy of DF508 also responded positively with VX-809, albeit at a lower success rate than individuals who had two copies of DF508. Based on this information, Vertex is planning additional studies of VX-809 and Kalydeco for people with just one copy of the mutation.

Another primary endpoint of this study was to determine the improvement of sweat chloride in the study population. A reduction of sweat chloride shows that this drug combination is likely causing a positive change in the function of the CFTR protein. An improper function of the CFTR is the known cause of CF, which would mean that a reduction in the chloride certifies that the medication is performing as expected, and is treating the underlying cause of CF. However, although improvements were shown for participants who had two copies of DF508 during the first 28 days of this study, results from the final 28 study days found no statistically significant reduction of sweat chloride.

Per the website, the success of this drug combination could boost the eligible pool of individuals with CF by up to ten times ( In early 2013, Vertex plans to begin a type of trial on Kalydeco and VX-809 on the CF population with two DF508 mutations that is designed to provide the U.S. Food and Drug Administration, and similar authorities in other countries, with data to decide whether or not to approve this potential drug (
A slideshow of Dr. Boyle’s presentation can be found at

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