Early Trial Results Indicate Cystic Fibrosis Drug Efficacy

(James. J. Caras, National Science Foundation)

Vertex Pharmaceuticals Inc. in Cambridge, Massachusetts says interim data from a clinical trial of its cystic fibrosis drugs point to improved lung function among patients who took the drugs. The results reported from the trial were for patients with two copies of the most common mutation of the cystic fibrosis regulator gene.

The phase 2 trial tests ivacaftor (marketed as Kalydeco), a Vertex drug already approved by FDA to treat cystic fibrosis, with the company’s drug candidate VX-809, among up to 160 patients at 24 locations with one or two copies of mutated gene. The double-blind study investigates different treatment periods of the drug combinations against placebos. The trial measures changes in sweat chloride, a biomarker for cystic fibrosis, as well as changes in lung function, defined as forced expiratory volume in 1 second.

Vertex reported findings for 37 patients with two copies of the mutation, who received the drug combination for 56 days, compared to 11 patients also with two copies of the mutation, who received placebos. The company says some 46 percent of the test patients experienced an improvement in lung function of 5 percentage points or more from initial baseline tests. Some 30 percent of the patients in the test group experienced a 10 percentage point increase in lung function.

None of the placebo patients experienced as much as a 5 point increase in lung function. Reductions in sweat chloride were also observed between days 28 and 56 of the trial, but not enough to be statistically significant. However, a statistically significant reduction in sweat chloride was observed in patients treated with VX-809 alone, compared to a baseline measure, up to day 28.

Patients with one copy of the mutated gene also took part in the trial, but not enough subjects had completed the study to make even preliminary conclusions. Vertex says it expects to have complete data on all patient groups by mid-2012, and plans a more comprehensive clinical study of the drugs pending the final results of the current trial.

Cystic fibrosis is caused by a defective gene which causes the body to produce abnormally thick and sticky fluid, called mucus that  builds up in the breathing passages of the lungs and in the pancreas.

Read more: Genome Institute to Fund Research on Rare Diseases, Medical Care

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