Facts
About Cystic Fibrosis
- Cystic fibrosis is
a genetic disease affecting approximately 30,000 children and adults
in the United States.
- CF causes the body
to produce an abnormally thick, sticky mucus, due to the faulty
transport of sodium and chloride (salt) within cells lining organs
such as the lungs and pancreas, to their outer surfaces. The
thick CF mucus also obstructs the pancreas, preventing enzymes from
reaching the intestines to help break down and digest food. Specialized
treatments are available to address these problems at CF Foundation-supported
care centers across
the country.
- CF has a variety of
symptoms. The most common are: very salty-tasting skin; persistent
coughing, wheezing or pneumonia; excessive appetite but poor weight
gain; and bulky stools. The sweat
test is the standard diagnostic test for cystic fibrosis. This
simple and painless test measures the amount of salt in the sweat.
A high salt level indicates that a person has CF.
- The treatment of CF
depends upon the stage of the disease and which organs are involved.
One means of treatment, chest physical therapy, requires vigorous
percussion (by using cupped hands) on the back and chest to dislodge
the thick mucus from the lungs. Antibiotics are also used to treat
lung infections and are administered intravenously, via pills, and/or
medicated vapors which are inhaled to open up clogged airways. When
CF affects the digestive system, the body does not absorb enough
nutrients. Therefore, people with CF may need to eat an enriched
diet and take both replacement vitamins and enzymes.
- One in 31 Americans
(one in 28 Caucasians) - more than 10 million people - is an unknowing,
symptom less carrier of the defective gene.
- An individual must
inherit a defective copy of the CF gene — one from each parent
— to have cystic fibrosis. Each time two carriers conceive
a child, there is a 25 percent chance that the child will have CF;
a 50 percent chance that the child will be a carrier; and a 25 percent
chance that the child will be a non-carrier.
Progress
Toward a Cure
Since the defective CF gene was discovered in 1989, the pace
of CF research has greatly accelerated. In 1990, scientists successfully
made copies of the normal gene, and added them to CF cells in laboratory
dishes, which corrected the defective cells. The next major step was
achieved in early 1993 when the first experimental gene therapy treatment
was given to a patient with CF. Researchers modified a common cold
virus to act as a delivery vehicle -
carrying the genes to the CF cells in the airways. Several Foundation-supported
studies are underway to test new gene delivery methods, such as fat
capsules (liposomes) and synthetic vectors. For more information on
CF gene therapy, please refer to the CF Foundation fact sheet entitled,
Gene Therapy and
CF.
New Treatments
The first new drug therapy developed exclusively for CF in
30 years was approved by the Food and Drug Administration (FDA) in
1993. In clinical trials, this mucus-thinning drug called Pulmozyme®,
reduced the number of respiratory infections and improved lung function.
In 1995, a four-year Foundation-supported study showed that the drug,
ibuprofen, reduced the rate of lung inflammation in children with
CF — under controlled conditions, and in high doses.
In late 1997, the FDA approved the drug
TOBI™
(tobramycin solution for inhalation). In clinical
trials, this reformulated version of the common antibiotic improved
lung function in people with CF and reduced the number of hospital
stays. The benefits of TOBI are that it can be delivered in a more
concentrated dose directly to the site of CF lung infections more
efficiently, and that it is preservative-free. The development
of TOBI should lead to a long line of other aerosolized antibiotics
for people with CF.
Beyond currently available antibiotics,
the CF Foundation pursues novel strategies that will lead to entirely
new forms of antibiotics. The promising compound, IB367, represents
one of an up-and-coming new class of drugs that should provide physicians
unique tools to better manage chronic CF lung infections.
In CF cells, salt does not move properly
because the protein product of the CF gene is defective -- and makes
a faulty channel for the salt (chloride) to exit. Scientists are therefore
looking for ways to get the chloride out of cells. INS365 is being
evaluated for its ability to stimulate cells to secrete chloride.
This, in turn, should lead to mucus that is less thick and sticky.
In addition, other treatment strategies
to correct the protein product of the gene are currently being tested
in clinical trials.
What makes these drugs so unique is that researchers appear to be
treating the causes of CF, not just the symptoms. However, even better
treatments are on the horizon. High-throughput
screening for CF opens many doors in the CF drug discovery process
by allowing scientists to test more compounds for their ability to
treat CF cells in a day than once possible in a year!
