30 April 2007
ByAppeared in BioNews 405
A new drug is being trialled in humans which has been able to cure Duchenne muscular dystrophy (DMD) in mice with symptoms of the disease. The drug, named PTC124, has been developed by scientists working at the University of Massachusetts Medical School and Pennsylvania University Medical School in conjunction with biotech company PTC Therapeutics Inc. Muscular dystrophy (MD) is the name for a group of genetic disorders in which muscles gradually waste over time. Mobility is lost and affected individuals have a reduced life span. There is currently no cure. DMD is the most severe and commonest form of the dystrophies - around 100 boys are born with the condition each year in the UK.
People with DMD have a mutation in the gene which codes for the dystrophin protein. About 15 per cent of patients have a type of mutation that results in a premature 'stop' signal. As the dystrophin gene is translated into protein, the incorrect signal prematurely stops the protein production and resulting in a non-functional version. In the mouse model, PTC124 was able to override the mutation and allow full-length copies of dystrophin to be produced. The drug did not stop correct stop signals in the genetic code being read. Similar 'nonsense' mutations are found in up to 1800 other genetic diseases that may also be treatable with the new drug. Human trials are currently underway in both DMD and cystic fibrosis.
Lead researcher Lee Sweeney of the University of Pennsylvania said, 'This new class of treatment has the potential to help a large number of patients with different genetic diseases that have the same type of mutation...Enough dystrophin accumulated in the muscles of the MD mice so that we could no longer find defects in the muscles when we examined them. For all intents and purposes the disease was corrected by treatment with PTC124'. It is thought that the results of the human trials will take some years. The work is published early online in the Journal Nature.