Gene therapy for pediatric AIDS

Gene therapy is an experimental treatment modality under investigation for applications to HIV-1 infection. We have developed retroviral vectors carrying anti-HIV-1 genes, demonstrated that these genes cause significant suppression of HIV-1 replication in cultures of primary hematopoietic cells, and performed a clinical trial in pediatric AIDS patients. Four HIV-1-infected children and adolescents underwent bone marrow harvest from which CD34+ cells were isolated and transduced by a retroviral vector carrying an RRE decoy gene. The cells were re-infused into the subjects, without complications, showing that gene transfer in pediatric AIDS patients in safe and feasible. However, gene-containing leukocytes in the peripheral blood were seen only at a low level and only in the first months following cell infusion. To attain some degree of efficacy, it will be necessary to achieve a higher level of gene transfer and to obtain sustained gene expression. We are currently developing new gene transfer methods and vectors designed to improve the results in future trials. If it becomes possible to reach the ideal goal of producing high percentages of T lymphocytes and monocytic cells that are resistant to HIV-1 infection, gene therapy could serve as a complement to antiretroviral drug therapy and help to sustain immunologic function.