In 1990, a clinical trial was started using retroviral-mediated transfer of the adenosine deaminase (ADA) gene into the T cells of two children with severe combined immunodeficiency (ADA- SCID). The number of blood T cells normalized as did many cellular and humoral immune responses. Gene treatment ended after 2 years, but integrated vector and ADA gene expression in T cells persisted. Although many components remain to be perfected, it is concluded here that gene therapy can be a safe and effective addition to treatment for some patients with this severe immunodeficiency disease.

We report here on a preliminary human autologous transplantation study of retroviral gene transfer to bone marrow (BM) and peripheral blood (PB)-derived CD34-enriched cells. Eleven patients with multiple myeloma or breast cancer had cyclophosphamide and filgrastim-mobilized PB cells CD34-enriched and transduced with a retroviral marking vector containing the neomycin resistance gene, and CD34-enriched BM cells transduced with a second marking vector also containing a neomycin resistance gene. After high-dose conditioning therapy, both transduced cell populations were reinfused and patients were followed over time for the presence of the marker gene and any adverse effects related to the gene-transfer procedure. All 10 evaluable patients had the marker gene detected at the time of engraftment, and 3 of 9 patients had persistence of the marker gene for greater than 18 months posttransplantation. The marker gene was detected in multiple lineages, including granulocytes, T cells, and B cells. The source of the marking was both the transduced PB graft and the BM graft, with a suggestion of better long-term marking originating from the PB graft. The steady-state levels of marking were low, with only 1:1000 to 1:10,000 cells positive. There was no toxicity noted, and patients did not develop detectable replication-competent helper virus at any time posttransplantation. These results suggest that mobilized PB cells may be preferable to BM for gene therapy applications and that progeny of mobilized peripheral blood cells can contribute long-term to engraftment of multiple lineages.

A B S T R A C T PurposeTo determine the ability to induce tumor-specific immunity with individual mutant K-ras-or p53-derived peptides and to monitor clinical outcome. Patients and MethodsPatients in varying stages of disease underwent genetic analysis for mutations in K-ras and p53. Thirty-nine patients were enrolled. Seventeen-mer peptides were custom synthesized to the corresponding mutation. Baseline immunity was assessed for cytotoxic T-lymphocyte (CTL) response and interferon gamma (IFN-␥) release from mutant peptide-primed lymphocytes. Patients' peripheral-blood mononuclear cells were pulsed with the corresponding peptide, irradiated, and applied intravenously. Patients were observed for CTL, IFN-␥, interleukin (IL) -2, IL-5, and granulocyte-macrophage colony-stimulating factor responses, for treatment-related toxicity, and for tumor response. ResultsNo toxicity was observed. Ten (26%) of 38 patients had detectable CTL against mutant p53 or K-ras, and two patients were positive for CTL at baseline. Positive IFN-␥ responses occurred in 16 patients (42%) after vaccination, whereas four patients had positive IFN-␥ reaction before vaccination. Of 29 patients with evident disease, five experienced a period of stable disease. Favorable prognostic markers were detectable CTL activity and a positive IFN-␥ reaction but not IL-5 release. Median survival times of 393 v 98 days for a positive versus negative CTL response (P ϭ .04), respectively, and of 470 v 88 days for a positive versus negative IFN-␥ response (P ϭ .02), respectively, were detected. ConclusionCustom-made peptide vaccination is feasible without any toxicity. CTL and cytokine responses specific to a given mutation can be induced or enhanced with peptide vaccines. Cellular immunity to mutant p53 and K-ras oncopeptides is associated with longer survival.