Vertex cystic fibrosis drug improves lung function

By Deena Beasley

LOS ANGELES, March 27 (Reuters) - Vertex Pharmaceuticals Inc (VRTX.O) said on Thursday that a small study of its experimental cystic fibrosis drug showed that two weeks of treatment resulted in a significant improvement in lung function.

The drug, known as VX-770, targets the underlying defect that causes the fatal disease, in which inadequate function of a key protein results in an imbalance of fluid and salt in the airways.

Vertex said the results are from a planned interim analysis of a mid-stage trial in 20 patients who carry the G551D mutation in the gene that causes cystic fibrosis.

This group accounts for about 5 percent of patients with the disease, said Dr. Frank Accurso, director of the Cystic Fibrosis Center at the University of Colorado School of Medicine in Denver and the trial's lead investigator.

"We saw an average improvement in lung function of 10 percent in patients receiving the highest dose, compared to less than 1 percent who received placebo," he said.

Patients with cystic fibrosis typically experience a decline in lung function of one to three percent a year.

In addition to lung function, the oral drug also was shown to improve function of a protein known as the cystic fibrosis transmembrane conductance regulator, or CFTR.

Accurso said it is "unprecedented" for an experimental drug to have such a significant effect on multiple measures of cystic fibrosis disease activity.

He said the trial involved patients with the G551D mutation because they produce more of the CFTR protein. Still, the investigator said VX-770 has the potential to treat CF patients with other mutations.

"We will need to do a longer-term trial ... in a larger number of patients," Dr. Accurso said.

He said the drug was well-tolerated, with one or two patients developing rashes and some having problems usually associated with the disease.

Cystic fibrosis, which produces a thicker-than-normal mucus that clogs the lungs and other organs, affects about 70,000 children and adults worldwide, according to the Cystic Fibrosis Foundation.

It is caused by a small genetic mutation, and children who inherit defective copies of the gene from both parents develop the disease.

Vertex said the trial results are being shared with regulatory authorities and leading investigators in order to identify the most rapid path forward for the compound.

The company said it plans to move forward in the second quarter of 2008 with the next part of the Phase II trial, which will enroll around 16 patients for dosing of VX-770 or placebo for 28 days.

The research was funded by Vertex and the Cystic Fibrosis Foundation. (Reporting by Deena Beasley; editing by Carol Bishopric)