Experimental Drug Ivacaftor May Extend Lives of Cystic Fibrosis Patients
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By Salynn Boyles
WebMD Health News
Reviewed by Laura J. Martin, MD
Nov. 2, 2011 -- Hopes are high that a new treatment soon could improve and possibly extend the lives of patients with the inherited disease cystic fibrosis.
In a study appearing in The New England Journal of Medicine, researchers report that the experimental oral drug ivacaftor, formerly known as VX-770, dramatically improved lung function and other symptoms in cystic fibrosis patients with a rare genetic mutation.
Studies are under way to determine if combination therapy with ivacaftor and another experimental drug could do the same thing in most other patients with the genetic disease.
The drugs target the disease process and not just symptoms and disease-related complications, as current cystic fibrosis treatments do.
CF Drug a Potential Game Changer
Cystic Fibrosis Foundation (CFF) president and CEO Robert J. Beall, PhD says he believes the research that led to the drugs will be a game changer for cystic fibrosis and possibly many other genetic diseases.
"This is the first time that an oral drug has been used to treat a basic defect in a genetic disease," he tells WebMD. "This research could very well open up new treatment horizons for people who suffer from many genetic diseases."
About 30,000 children and adults in the United States and 70,000 people worldwide have cystic fibrosis. It's a disease of the glands that produce sweat and mucus, and causes the body to produce very thick, sticky secretions that clog the lungs and keep the pancreas from working optimally.
Symptoms of the disease, caused by a defective gene, include frequent lung infections, wheezing, shortness of breath, coughing, poor growth, and difficulty gaining weight.
Patients also have very salty sweat because their sweat glands are not able to properly conduct chloride. The genetic defect does not allow chloride to properly move in and out of cells, so it builds up in sweat as sodium chloride (salt). Measuring the amount of chloride in sweat has been the standard test for cystic fibrosis for decades.
Fifty years ago, most children with the disease died before they entered kindergarten. Today, thanks to treatments that help control symptoms, the average life span of patients is about 38 years.
Dramatic Improvement in Lung Function
The newly reported study included 161 cystic fibrosis patients as young as age 12 with a specific disease mutation known as G551D. About 4% of patients have the mutation.
All the patients in the study continued taking treatments to control their symptoms. Half also took the experimental oral drug twice a day for 48 weeks, while the other patients took placebo pills.
Over the course of the study, patients taking the experimental drug gained an average of 6 pounds more than the placebo-treated patients. And six months after beginning treatment their lung function had improved by 17%. Patients who took a placebo showed almost no improvement in lung function.
"When you consider that the typical cystic fibrosis patient loses about 2% of lung function a year, a 17% improvement in lung function is remarkable," Beall says.
The ivacaftor-treated patients also saw dramatic reductions in their sweat's chloride content -- an indication that the drug was working, as researchers had hoped, to modify the disease process by restoring the balance of salt and water within the body.
"When I first saw the results, I thought they couldn't be real," researcher Bonnie Ramsey, MD, of Seattle Children's Hospital and the University of Washington School of Medicine tells WebMD. "You just don't see changes like this."
FDA Considering Ivacaftor Approval
Most patients in the study have remained on the drug, and researchers will present an additional 12 weeks of follow-up this week at the 25th Annual North American Cystic Fibrosis Conference in Anaheim, Calif., later this week.
They will also present data on children between the ages of 6 and 11 with the mutation who were treated with the experimental drug.
Cambridge, Mass.-based Vertex Pharmaceuticals, which is developing ivacaftor, is also developing a second experimental drug for use in patients with the most common cystic fibrosis gene mutation -- F508del.
About 90% of patients carry this mutation, and phase II trials are now under way to determine if the combination of the two experimental drugs can improve outcomes in these patients.
Vertex spokeswoman Dawn Kalmar says the FDA is reviewing the data on ivacaftor and the drug could be approved as early as the middle of next year.
Could Treating Babies Stop Disease?
Case Western University vice president for medical affairs Pamela B. Davis, MD, PhD, says there is real hope that the treatment approach will extend the lives of patients and improve quality of life for many years.
There is also the potential to stop the disease in its tracks if the drugs can be safely given to infants and very young children, she says.
Because early screening for cystic fibrosis is now the law in all 50 states, most cases of the disease are identified in newborns.
"We now have a chance to prevent lung damage from occurring if we can treat early enough," she says. "That would be tremendously exciting."
Human Genome Project, Gates Foundation Played Part
In an editorial published with the study, Davis writes that the experimental drugs are the result of more than two decades of intense private and publicly funded research, beginning with the discovery of the cystic fibrosis gene in 1989.
This included a $20 million grant to the Cystic Fibrosis Foundation from the Bill & Melinda Gates Foundation in 1999 to research new drugs -- the largest single grant ever given to the foundation.
Davis says the research shows that much of the promise of the Human Genome Project, which made the discovery of the cystic fibrosis gene possible, has yet to be fulfilled.
"It took us 22 years to get to this point with a whole lot of resources and collaboration to develop screening tests and drugs," she tells WebMD. "I think one lesson here is stay tuned. We ain't seen nothing yet from the Human Genome Project."