Adenovirus retargeting and systemic delivery.

The useful application of gene therapy strategies is frequently thwarted by inadequate systems for delivery and expression of therapeutic transgenes within target cell populations. This is particularly important in diseases, such as metastatic cancer, where the target cells are disseminated around the body at the time of diagnosis. Even where target issues are relatively localised, gaining adequate transgene expression can still limit the usefulness of the approach; indeed, the only situations where gene therapy has been applied with success relate to target cell populations (such as haematopoietic stem cells) that can be returned to the patient following transduction ex vivo, or where a significant proportion of target cells can be transduced following local injection of the vector. For the vast majority of potential therapies, inadequate transgene delivery and expression remain a major bottleneck to progress.