The randomized, double-blind, placebo-controlled phase II study was conducted in cystic fibrosis patients (adults) who have two copies (homozygous) of F508del, the most common mutation in the cystic fibrosis transmembrane conductance regulator (:CFTR) gene.
Four once-daily doses of VX-661 (10, 30, 100 and 150 mg) administered with ivacaftor (150 mg twice-daily) were evaluated in the study for 28 days. While VX-661 is a CFTR corrector, ivacaftor is a CFTR potentiator. VX-661 was also evaluated as a monotherapy in a separate group of patients. Primary endpoints were safety, tolerability and change in sweat chloride with change in lung function being a secondary endpoint.
Vertex Pharma said that dose-dependent, mean relative improvements in lung function were observed both within the group and compared to placebo. Statistically significant mean relative improvements in lung function were observed in the 100 and 150 mg combination groups compared to placebo. The results provide further support to Vertex Pharma’s strategy of combining a corrector with ivacaftor.
VX-661 was found to be well-tolerated as monotherapy as well as combination therapy. Going forward, Vertex Pharma intends to evaluate VX-661 in additional studies following discussions with regulatory authorities.
Vertex Pharma’s shares were up significantly in pre-market trading. We are pleased with the company’s progress with its cystic fibrosis candidates.
Lead cystic fibrosis candidate, VX-809, is currently in phase III development. Positive 24-week safety and efficacy data on VX-809 would allow Vertex Pharma to seek US Food and Drug Administration (:FDA) approval in 2014.
The company has another cystic fibrosis candidate, VX-983, which is currently in a phase I multiple-ascending-dose study in healthy volunteers. VX-983 is scheduled to move into a 28-day study in combination with ivacaftor in the second half of this year.
We note that ivacaftor is currently approved in the US, Canada and the EU under the trade name Kalydeco for the treatment of cystic fibrosis patients (six years and older) who have at least one copy of the G551D mutation in the CFTR gene. Kalydeco, which delivered revenues of $171.6 million in 2012, is off to a strong start and should continue performing well in 2013.
We are optimistic on the growth prospects of Vertex Pharma’s cystic fibrosis franchise. Vertex Pharma currently carries a Zacks Rank #1 (Strong Buy).
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