(US) Muscular dystropy drug also fights CF PDF Print E-mail
April 21, 2008
BIRMINGHAM AL – An experimental drug that has proven effective in
treating muscular dystrophy also works for cystic fibrosis, according
to researchers at the University of Alabama at Birmingham (UAB).

The new study is the latest on a compound called PTC124, which helps
to "rescue" faulty proteins that lead to illnesses. The drug holds
promise in treating more than 2,400 genetic diseases caused by a
certain class of DNA mutation.

In the UAB tests performed on mice, PTC124 restored to normal
function up to 29 percent of the cases of abnormal cystic-fibrosis
(CF) protein.

The findings are published in the online version of the journal
Proceedings of the National Academy of Sciences and will soon appear
in a print edition.

Restored a quarter of normal function
The study adds to research published last year in the journal Nature,
which showed PTC124 restored up to 25 percent of the missing or
abnormal protein function in mice with Duchenne muscular dystrophy.

"Our study shows strong pre-clinical evidence that PTC124 is capable
of suppressing `nonsense mutations' that cause cystic fibrosis," said
David Bedwell, Ph.D., professor in the UAB Department of Microbiology
and lead author on the study.

"We think this provides strong evidence for clinical trials with
PTC124 in CF patients with this kind of mutation."

A gene that carries a `nonsense mutation' produces a shortened or
faulty protein that degrades in the body. The absence of that protein
is what leads to disease, Bedwell said.

Nonsense mutations
An estimated one-third of gene defects responsible for human disease
are thought to come from `nonsense mutations.' In the case of CF, the
absence of a certain protein leads to an imbalance of salt and water
in the linings of the lungs and other membranes.

The UAB study showed that PTC124 allowed the protein to be made in
mouse cells where it was previously absent, and it was delivered in a
specific location that helped restore salt and water balance in
membranes.

"The preclinical and clinical data on PTC124 support our hope that
this drug will be an important disease-modifying therapy for cystic
fibrosis," said Robert J. Beall, Ph.D., president and chief executive
officer of the Cystic Fibrosis Foundation in Bethesda, Md.

"We look forward to the next stage of clinical development to
demonstrate the benefits of this promising therapy."

Also in the UAB study, PTC124 was shown to be highly selective for
fixing only disease-causing mutations, while it spared normal genes,
Bedwell said.

The compound has been granted orphan-drug status by the U.S. Food and
Drug Administration for the treatment of Duchenne muscular dystrophy
and CF, according to the biopharmaceutical company PTC Therapeutics,
Inc. of South Plainfield, N.J. It works in an oral form.

The UAB study was funded by PTC Therapeutics with assistance from the
National Institutes of Health.
 
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