Regulated gene expression systems

Most gene therapy research to date has focused on solving the delivery prob lem - getting genes efficiently and stably into target cells and tissues. T hose working on systems for regulating the expression of genes once deliver ed have often been accused of trying to run before they can walk. Yet regul ation is likely to be essential if gene therapy is to realize its full pote ntial as a mainstream clinical option for delivering proteins. Dramatic pro gress has been made in designing and testing systems in which expression is controlled by orally active drugs. The next few years should see the first clinical trials of drug-regulated gene therapies.