Cancer gene therapy--first international conference. 8-9 July 1999, Hammersmith Hospital, London, UK

The failings of the cancer gene therapies that have so far been tested in clinical trials are that they do not reach sufficient target cells and are not toxic enough. The eventual success of many strategies may also depend on their ability to elicit a strong antitumor immune response. Unsurprisingly, therefore, the focus of this meeting, the first of the International Society of Cancer Gene Therapy, was on new strategies currently in preclinical development that address these problems, and relatively little new clinical information was presented. There was much interest in a new class of therapeutic genes, those encoding fusogenic membrane glycoproteins, which are very toxic and have the potential to elicit a potent bystander effect and a strong immunogenic response. The aim of another strategy that shows considerable promise is to improve the toxicity of replication-conditional adenoviruses by replacing deleted adenoviral genes with cytotoxic or suicide genes. Disappointingly, there was little discussion of new vector systems that might improve gene delivery. The most exciting development in ex vivo immunogene therapies presented was progress towards the development of a streamlined 'off the shelf' immunogene therapy for relapsing leukemia patients who have undergone bone marrow transplants. In addition, a few promising immunotherapies were discussed that may provide several starting points for the development of new gene therapies that are effective in eliciting tumor immunogenicity.