Find the story and podcast here: http://www.npr.org/blogs/health/2013/01/02/168353348/drug-fulfills-promise-of-research-into-cystic-fibrosis-gene
by JOE PALCA
January 02, 2013 3:04 PM
4 min 24 sec
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The promise of genetic medicine is beginning to be fulfilled,
but it's been a long, hard slog.
Take the story of Kalydeco.
It's designed to treat people with a lung disease called cystic fibrosis. While
not quite a cure, the drug is extremely effective for some CF patients.
But the success of Kalydeco has been more than two decades in
the making.
A good starting point for the story is Aug. 24, 1989. That's the
day scientists from the U.S. and Canada announced the discovery of the gene
associated with the disease. It was the early days of gene hunting, and the CF
gene was a big prize.
CF is the most common genetic disease in Caucasians. When people
inherit a damaged form of the CF gene, a critical protein inside cells doesn't
work properly. As a result, sticky mucus builds up in a patient's lungs,
causing infections and making it hard to breathe.
The announcement was supposed to be made in conjunction with
three papers in
the Sept. 8 issue of Science, but a reporter for Reuters got hold of the story early. Science took the unusual
step of allowing the scientists to speak to the media before publication.
At the time, scientists predicted that a genetic test for CF was
just around the corner. But they also thought a drug to treat the disease was
in reach.
The first prediction turned out to be right. "But it wasn't
until 20 years later that we were able to find drugs that directly target the
underlying cause of cystic fibrosis," says Fred Van Goor, who led the team
at what is now Vertex Pharmaceuticals that
developed Kalydeco. "So it was a long time between the discovery of the
gene and the discovery of Kalyedco."
Kalydeco is one of the first drugs that is
effective at combating the root causes of a genetic disease.
It took awhile to find a drug that would help restore the
function of the protein the CF gene makes. "We tested over 600,000
chemicals in cells with the defective protein that causes cystic
fibrosis," says Van Goor.
One of those chemicals ultimately became a successful drug, but
it had to be modified so patients could take it by mouth, and so it would last
the right length of time in a patient's body.
From the start, Van Goor and his colleagues knew there was a
problem with Kalydeco: It only works on a small subset of people with CF. They
have to have a particular mutation in the CF gene, or the drug is of little
use.
But for people who do have that mutation, the drug works
remarkably well.
Emily Schaller was in one of the early studies of Kalydeco. As
part of the study, researchers first gave her a placebo, then switched her to
the active drug. She knew within days that something was different.
"I was with my brother in Florida, and we were walking down
the street, and I took a deep breath, and when I took a deep breath in and I
let it out, I didn't cough," says Schaller.
"But not only did I not cough, but I felt that my lungs were clear, and
that something huge had happened. It was just something I had never felt in my
life before."
Schaller isn't cured. She still has a damaged CF gene. The only
way to fix that would be gene therapy,
where a healthy form of the gene would supplant the damaged one. Although it
seems simple in theory, in practice gene therapy has been incredibly difficult
to accomplish.
Schaller isn't particularly bothered by that. "Everyone
talks about curing a disease — cure CF, cure these other diseases. [But]
Kalydeco controls CF at the basic defect, so I'm OK with the other 'c' word,
control, because I'm living it and I've never felt better in my life."
The time from gene discovery to successful drug may be
shortening, but there are only a handful of successful drugs so far, and for a
while at least, the appearance of new ones will be slow.
They're also likely to be expensive. Kalydeco costs in the
neighborhood of $300,000 per year.
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