Allelic Exclusion and Peripheral Reconstitution by TCR Transgenic T Cells Arising From Transduced Human Hematopoietic Stem/Progenitor Cells

Abstract

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-β 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.

Induction of WT1-specific human CD8+ T cells from human HSCs in HLA class I Tg NOD/SCID/IL2rgKO mice

“…[40][41][42] ) cells for transplant, to exclude the possibility of residual preformed human T cells in the graft. Purified WT1-TCR-transferred HSCs still retained the multilineage differentiation capacity.…”

Genetic engineering of hematopoietic stem cells to generate invariant natural killer T cells

“…Overexpression of prerearranged αβ TCR genes in HSCs has been shown to induce allelic exclusion and block the rearrangements of endogenous TCR genes in the resulting conventional αβ T cells (13). Study of the iNKT cells generated in the B6-miNKT mice revealed that these cells expressed the transgenic TCR (Vβ8 + ), but not the other TCR Vβ chains analyzed in our experiment (Fig.…”

“…As an alternative, a TCR-engineered HSC adoptive transfer strategy could overcome these limitations and become clinically applicable. Since its demonstration in mice in the early 2000s, this HSC-engineered T-cell strategy has been widely used to successfully generate both mouse and human antigen-specific conventional αβ T cells in multiple mouse and humanized mouse models (8)(9)(10)(11)(12)(13). Human clinical trials testing this strategy for treating melanoma are also ongoing (14).…”

Noninvasive detection of tumor-infiltrating T cells by PET reporter imaging

“…Only a fraction of the CD34 cells are gene modified and a diverse T cell repertoire will develop in vivo (15,32,34). It is possible that the F5-expressing cells may be eliminated by negative selection due to TCR mismatching from endogenous TCR and F5 TCR.…”

“…Expansion of patient peripheral blood mononuclear cells (PBMCs) can alter the tumor-homing function, reducing the efficacy of infused cells (12). Nonspecific expansion of PBMCs or TCR mismatching when cells are engineered to express a specific TCR can increase the number of alloreactive T cells, possibly causing issues of autoimmunity and graft-versus-host disease (13)(14)(15). In the case of engineered TCRs or CARs, these cells have the potential to recognize on-target/ off-tumor sites of proper epitope display or of epitopes similar to the target (4,13).…”