Gene therapy sees early success for neurodegenerative disease

Doctors marked the first successful use of an attenuated HIV virus to carry a therapeutic gene into a patient’s cells on October 28th, as two 7-year-old Spanish children with ALD began showing early signs of success from the pioneering gene-therapy treatment.

HIV is a promising vector for transferring corrective genes into a host due to its ability to directly into cell nuclei. But until now it hadn’t been proven in a clinical setting. The results raise hopes for a treatment for adrenoleukodystrophy (ALD), and this early success potentially opens the door to better treatments for many other diseases involving the bone marrow and blood cells, such as leukaemia, thalassemia and sickle-cell disease.

Working in collaboration with the Californian biotech company Cell Genesys, Inserm researchers, Patrick Aubourg and Natalie Cartier, first cultured the children's bone-marrow progenitor cells — which give rise to all blood cell types — and then transferred the corrective gene to them using the HIV virus. They then destroyed the children's existing bone marrow using chemotherapy, and reintroduced the modified cells, which took hold within a month to produce new bone marrow and blood cells. Samples taken showed exceptional results, with half of the new cells containing the introduced gene, and 20-30% expressing the corrective protein.

Although the initial results are encouraging, caution is warranted. Many previous gene-therapy trials have failed because of serious problems with side effects. It will also take another 18 months of follow-up before the team can be reasonably sure that their gene transfer remains stable, and that the level of corrective protein expressed is sufficient to prevent clinical symptoms from developing.

http://www.nature.com/news/2007/071030/full/news.2007.204.html