Long-term survival and concomitant gene expression of ribozyme-transduced CD4+ T-lymphocytes in HIV-infected patients

BACKGROUND: An anti-HIV-1 tat ribozyme, termed Rz2, has been shown to inhibit HIV-1 infection/replication and to decrease HIV-1-induced pathogenicity in T-lymphocyte cell lines and normal peripheral blood T-lymphocytes. We report here the results of a phase I gene transfer clinical trial using Rz2. METHODS: Apheresis was used to obtain a peripheral blood cell population from each of four HIV-negative donors. After enrichment for CD4+ T-lymphocytes, ex vivo expansion and genetic manipulation (approximately equal aliquots of the cells were transduced with the ribozyme-containing (RRz2) and the control (LNL6) retroviral vector), these cells were infused into the corresponding HIV-1-positive twin recipient. Marking was assessed over an initial 24-week period and in total over an approximate 4-year period. RESULTS: The gene transfer procedure was shown to be safe, and technically feasible. Both RRz2- and LNL6-gene-containing peripheral blood mononuclear cells (PBMC) were detected at all time points examined to 4 years. There was concomitant gene construct expression in the absence of the need for ex vivo peripheral blood cell stimulation and there was no evidence of immune elimination of the neoR T-lymphocytes nor of silencing of the Moloney murine leukemia virus long terminal repeat. CONCLUSIONS: The proof of principle results reported here demonstrate safety and feasibility of this type of gene transfer approach. While not specifically tested, T-lymphocytes containing an anti-HIV gene construct may impact on HIV-1 viral load and CD4+ T-lymphocyte count, potentially representing a new therapeutic modality for HIV-1 infection.