Allelic exclusion and peripheral reconstitution by TCR transgenic T cells arising from transduced human hematopoietic stem/progenitor cells.

Transduction and transplantation of human hematopoietic stem/progenitor cells (HSPC) with the genes for a T-cell receptor (TCR) that recognizes a tumor-associated antigen may lead to sustained long-term production of T cells expressing the TCR and confer specific antitumor activity. We evaluated this using a lentiviral vector (CCLc-MND-F5) carrying cDNA for a human TCR specific for an HLA-A*0201-restricted peptide of Melanoma Antigen Recognized by T cells (MART-1). CD34(+) HSPC were transduced with the F5 TCR lentiviral vector or mock transduced and transplanted into neonatal NSG mice or NSG mice transgenic for human HLA-A*0201 (NSG-A2). Human CD8(+) and CD4(+) T cells expressing the human F5 TCR were present in the thymus, spleen, and peripheral blood after 4-5 months. Expression of human HLA-A*0201 in NSG-A2 recipient mice led to significantly increased numbers of human CD8(+) and CD4(+) T cells expressing the F5 TCR, compared with control NSG recipients. Transduction of the human CD34(+) HSPC by the F5 TCR transgene caused a high degree of allelic exclusion, potently suppressing rearrangement of endogenous human TCR-ß genes during thymopoiesis. In summary, we demonstrated the feasibility of engineering human HSPC to express a tumor-specific TCR to serve as a long-term source of tumor-targeted mature T cells for immunotherapy of melanoma.