Vertex Unveils Exciting Data for Cystic Fibrosis Drug
Feb24

Vertex Unveils Exciting Data for Cystic Fibrosis Drug

In one of those rare cases of good science translating directly into good medicine, Vertex Pharmaceuticals yesterday unveiled positive results from a Phase III trial of VX-770, a small molecule that treats the underlying defect of cystic fibrosis. The data “are very fresh, but nonetheless unambiguous and stunningly clear,” Vertex’s CSO Peter Mueller told analysts on a call yesterday. Further, they clear the way for Vertex to file for regulatory approval for VX-770 in the U.S. and Europe in the second half of this year. Before we get into the details of that data, a quick review of cystic fibrosis. As we described back in 2008, folks with CF have a mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which carries the recipe for making a protein that shuttles chloride ions from one side of a cell membrane to the other. That faulty gene means that people with CF absorb too much salt and have a hard time secreting it. Without the right balance of hydration, their lungs become dotted with dried-out pockets that get clogged with thick mucus, an environment ripe for bacteria growth. Patients suffer from chronic infections, often with the most pernicious of bugs, and take a panoply of antibiotics and other treatments to manage the symptoms of their disease. Vertex’s drug is generating excitement because it addresses the underlying cause of the disease. Think of CFTR as a gate that allows chloride ions out of the cell. Depending on the mutation that causes a patient’s CF—there are a handful of genetic malfunctions—that gate might be rusty, and not opening right, or, more commonly, there simply aren’t enough gates. VX-770 is being tested in people with a mutation akin to the former, and works to increase the flow of chloride ions through the gate, thereby restoring the right level of hydration in the lungs. In the Phase III trial of 161 people, the drug clearly met its primary endpoint of improving lung function. After 48 weeks on the drug, there was a relative improvement in lung function of 16.9% compared to placebo, and the absolute improvement (calculated by dividing the relative improvement by the baseline lung function)  of 10.6%. “This improvement in lung function both on an absolute and relative basis is particularly significant since it came on top of the other therapies patients continue to receive,” Vertex’s chief medical officer Robert Kauffman said yesterday. One of the most striking pieces of information gathered in this trial was the effect on the rate of pulmonary exacerbations, or periods when their disease worsens, Kauffman said. While the ability to improve lung function is critical, for...

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