Phase 3 Trial Successful for Vertex Pharmaceutical's Cystic Fibrosis Drug
Cystic fibrosis (CF) is an inherited disease caused by a defective gene. It affects about 30,000 children and adults in the United States. There are more than 1,000 mutations of the CF gene and many therapies are in development for potentially curing the disease or lessening the symptoms. The Cystic Fibrosis Foundation and Vertex Pharmaceuticals have announced that their oral medication called VX-770 has shown very promising results in a Phase 3 study.
VX-770 is a CFTR modulator, designed to correct the function of a defective protein made by the CF gene. About four percent of patients with cystic fibrosis carry at least one copy of a mutation called G551D which causes impaired chloride transport in the lungs, resulting in the accumulation of sticky mucus. It is the second most common mutation among CF patients.
In the trial called STRIVE, 83 patients aged 12 and older with the G551D mutation were assigned to take oral VX-770 twice daily. Seventy-eight patients were given a placebo. Baseline FEV1 was 63.5% of the predicted value in the experimental group and 63.7% in the control group. FEV stands for forced expiratory volume and it is an important measure of pulmonary function.
Patients who took VX-770 showed a marked improvement in lung function at 24 weeks. FEV1 improved by an absolute 10.6% compared to the patients on the placebo. This improvement was sustained for the duration of the 48-week trial.
The patients were also 55% less likely to have a pulmonary exacerbation, had significant reductions in sweat chloride (a marker of improved CFTR function), and gained an average of 6.8 pounds. Patients also reported fewer respiratory symptoms.
Common adverse events in the VX-770 group included headache, upper respiratory tract infections, nasal congestion, rash, dizziness, and bacteria in the sputum.
“These results are highly encouraging. They provide scientific evidence that support our long-standing belief that targeting the underlying defect of CF may have a profound effect on the disease,” said Robert J. Beall, Ph.D., president and CEO of the Cystic Fibrosis Foundation. “The results also offer significant hope that a similar approach to treatment may help the majority of patients living with CF.”
Vertex Pharmaceuticals is also conducted two other studies with VX-770. The DISCOVER trial, in Phase II, is assessing safety and effectiveness in patients with the most common cystic fibrosis mutation, ΔF508. The ENVISION study is ongoing in children ages 6 to 11 with the G551D mutation.
The company plans to submit a New Drug Application for VX-770 to the US Food and Drug Administration (FDA) in the second half of 2011. Generally, it takes the FDA between 6 to 12 months to review and rule on an application.