New Findings Raise Questions About Process Used to Identify Experimental Drug for Rare Genetic Diseases
Posted Feb 18 2009 11:47am
A study by National Institutes of Health (NIH) researchers has revealed surprising new insights into the process used to initially identify an experimental drug now being tested in people with cystic fibrosis and muscular dystrophy. Researchers emphasized that the clinical implications of their findings are unclear, but said the results suggest more work may be needed to make sure the screening process to select promising agents was not flawed by its effects on a firefly enzyme used as a marker. The study was published today in the Proceedings of the National Academy of Sciences (PNAS).
Over the past several years, an experimental drug called PTC124 has generated excitement among those seeking treatments for inherited diseases caused by a type of genetic alteration that leads to production of abnormally short proteins. Scientists refer to such alterations as nonsense mutations. About 10 percent of cystic fibrosis cases and about 15 percent of Duchenne muscular dystrophy cases are thought to arise from nonsense mutations. In addition, nonsense mutations may affect a substantial portion of the approximately 25 million Americans suffering from other rare, genetic disorders.
The enzyme that makes fireflies glow, called luciferase, is widely used in biomedical experiments and in high-throughput screening often utilized to discover drugs. In a positive reaction, the tested material literally lights up.