Adoptive Transfer of CD8 ⁺ T Cells Generated from Induced Pluripotent Stem Cells Triggers Regressions of Large Tumors Along with Immunological Memory

Current approaches to adoptive T cell therapy are limited by the difficulty of obtaining sufficient numbers of T cells against targeted antigens with useful in vivo characteristics. Theoretically, this limitation could be overcome by using induced pluripotent stem cells (iPSCs) that could provide an unlimited source of autologous T cells. However, the therapeutic efficacy of iPSC-derived regenerated T cells remains to be demonstrated. Here we report the first successful reprogramming of T-cell receptor (TCR) transgenic CD8(+) T cells into pluripotency. As part of the work, we established a syngeneic mouse model for evaluating in vitro and in vivo antitumor reactivity of regenerated T cells from iPSCs bearing a rearranged TCR of known antigen specificity. Stably TCR retained T cell-derived iPSCs differentiated into CD4(+)CD8(+) T cells that expressed CD3 and the desired TCR in vitro. Stimulation of iPSC-derived CD4(+)CD8(+) T cells with the cognate antigen in the presence of IL-7 and IL-15 followed by expansion with IL-2, IL-7 and IL-15 generated large numbers of less-differentiated CD8(+) T cells with antigen-specific potent cytokine production and cytolytic capacity. Furthermore, adoptively transferred iPSC-derived CD8(+) T cells escaped immune rejection, mediated effective regression of large tumors, improved survival, and established antigen-specific immunological memory. Our findings illustrate the translational potential of iPSCs to provide an unlimited number of phenotypically defined, functional, and expandable autologous antigen-specific T cells with the characteristics needed to enable in vivo effectiveness.