according to figures published by the Journal of Gene Medicine in January 2007, there are 1,260 gene therapy clinical trials in progress. Of these, 27 have reached Phase III and 13 Phase II/III, showing that a number of products are edging close to market.
The gene therapy paradigm has evolved since the original concept of using introduced genes to replace ones that are defective or missing. Products in development are delivering a range of genes, with a range of therapeutic objectives.
This evolution of the technology means that treating inherited gene defects is no longer the leading objective. Of the 1,260 gene therapy trials currently in progress, 67 percent are in cancer, while inherited single gene defects account for 8.4 percent.
The trials have shown that gene therapy can provide significant clinical benefits with good safety profiles in hitherto difficult, or impossible, to treat diseases. TroVax, for example, has been in nine studies involving more than 180 patients. There have been no serious adverse events and more than 90 per cent of patients mounted an immune response. This has resulted in high levels of tumour shrinkage and indications of survival benefit, with a correlation between the level of clinical benefit and the strength of the immune response.
The work is at an early stage aimed at establishing the safety and efficacy of gene transfer to the eye, and that gene therapy for many common conditions including macular degeneration, which affects about 500,000 mainly elderly people in Britain, was many years away.
Professor Ali, the head of the division of molecular therapy at UCL’s Institute of Ophthalmology said: “If we can establish the technique of delivering genes to the retina, it paves the way for applying it to other inherited disorders for which there is currently no treatment. Then in the longer term that could open the way to the treatment of common conditions such as macular degeneration, for which there are treatments but which aren’t particularly good.
“The advantage of using gene therapy over drugs is that you can give it as a single treatment to the back of the eye, avoiding the need for repeated use of drugs. We anticipate the gene transfer is life long.”
This therapy may not only keep people slim in the future. Other studies suggested it may also help raise good cholesterol, lower bad cholesterol, and help ward off type-2 diabetes.