Cystic fibrosis, an illness that affects 40,000 Americans, has proved a difficult disease to fight over the past few decades.
But continual advances in research, especially in gene replacement and the development of new drugs, are providing hope for patients and increasing the length and quality of their lives.
Gene therapy is the focus of researchers' efforts as they attempt to move from treatment to a cure for CF, a hereditary disorder that affects the respiratory, digestive and reproductive systems.
The genetic defect in CF causes the lungs to become covered with a sticky mucus that is hard to remove and promotes infection by bacteria. As a result, people with CF suffer from chronic lung problems and digestive disorders.
"CF affects every organ system that has a gland that secretes something," said Dr. Joseph Majure, director of Pediatric Graduate Medical Education at the Medical Center. He said abnormalities in sweat, mucus and pancreatic juices are what cause "the progressive course of the disease--the thick mucus in the lungs leads to infection and inflammation that will eventually scar and destroy the healthy lung tissue."
Most CF patients undergo a daily regimen, administered in the morning and evening, that includes numerous aerosol therapy treatments for opening bronchial tubes, along with antibiotics and vitamins taken with food.
Manual chest percussion is performed to help clear mucus from the lungs, and patients take pancreatic enzymes to replace enzymes necessary for digestion and absorption of nutrients.
As of the 1960s, roughly 30 years after CF was first discovered and described as an incurable disease with early death, life expectancy for patients was only about five years. Current life expectancy is over 30 years.
Infants born today may expect to live until their mid-40s. "By 2010," said Dr. Tom Murphy, a director of Duke's CF and Pediatric Pulmonary Center. "The majority of CF-affected individuals will be adults."
CF research has been focused on both obtaining a cure and identifying a specific cause. Since 1989, when researchers pinpointed the gene that causes CF, laboratory efforts have been concentrated on the development of replacement gene therapy, Murphy said.
Researchers have successfully transferred a normal gene into patients with CF, but Murphy said the process has not been perfected. The insertion of genetic material into bronchial lining cells and airway inflammation that occurs as a result of the transportation of vectors have been obstacles to gene replacement.
"Everyone still believes that these are soluble technical problems," Murphy added. "But it is likely that their solution will require several years."
Researchers' optimism is also bolstered by promising new drugs to treat CF, which are targeted at decreasing the amount of inflammation in the lungs and correcting the defective product of the affected gene.
New therapies, however, are costly. Drugs like Pulmozyme, released in 1993, the first new drug for CF in 30 years, and TOBI, an antibiotic inhaled into the lungs, each cost over $2,000 per month. A patient's essential daily treatment routine may cost up to $12,000 a month, Majure said.
In addition, information about the cell biology of the CF defect, a channel in bronchial and gut lining cell, is expected to produce a number of new drugs.
"These treatments, if successful, will represent a major breakthrough in the care of CF patients, because they will attack the root cause of CF lung disease," said Dr. Terry Noah, pediatric pulmonology chief at the University of North Carolina Cystic Fibrosis Center. "It is likely that this type of new treatment will significantly prolong the lives of CF patients, and improve their quality of life."
Life expectancy will be prolonged, because it is already happening, even without major drug therapy breakthroughs, Murphy said. "Everyone adapts to chronic illness."
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