Abstract
Adoptive transfer of antigen-specific CD8+ T cells can effectively treat patients with metastatic melanoma. Recent efforts have emphasized the in vitro generation of antitumor T cells by transduction of genes encoding antitumor T-cell receptors. At present, lentiviral vector-mediated transduction of CD8+ T cells relies on anti-CD3/CD28 bead stimulation; however, this method fails to efficiently expand CD8+ T cells. Herein we sought to establish a methodology for lentiviral vector transduction using optimal activating agents for efficient gene delivery and robust expansion of CD8+ T cells. To overcome the inability of anti-CD3/CD28 beads to efficiently expand CD8+ T cells, we evaluated alternative activating agents including feeder cells from allogeneic peripheral blood mononuclear cells and plate-bound anti-CD3 antibody. Analyses of gene transfer, cell phenotype, fold expansion, and biologic activities were used to determine the optimal methodology. Plate-bound anti-CD3 provided an ideal activation platform that afforded optimal lentiviral vector-mediated gene transfer efficiency (up to 90%), and coupled with peripheral blood mononuclear cells feeder cells yielded up to 600-fold expansion of CD8+ T cells within 12 days. The T-cell antigen receptor (TCR) engineered CD8+ T cells conferred specific antitumor activity and many displayed a central memory-like phenotype. The methodology described here could be readily applied for engineering CD8+ T cells with antitumor specificity for human adoptive immunotherapy.