Clinical successes demonstrated by chimeric antigen receptor T-cell immunotherapy have facilitated further development of T-cell immunotherapy against wide variety of diseases. One approach is the development of “off-the-shelf” T-cell sources. Technologies to generate T-cells from pluripotent stem cells (PSCs) may offer platforms to produce “off-the-shelf” and synthetic allogeneic T-cells. However, low differentiation efficiency and poor scalability of current methods may compromise their utilities. Here we show improved differentiation efficiency of T-cells from induced PSCs (iPSCs) derived from an antigen-specific cytotoxic T-cell clone, or from T-cell receptor (TCR)-transduced iPSCs, as starting materials. We additionally describe feeder-free differentiation culture systems that span from iPSC maintenance to T-cell proliferation phases, enabling large-scale regenerated T-cell production. Moreover, simultaneous addition of SDF1α and a p38 inhibitor during T-cell differentiation enhances T-cell commitment. The regenerated T-cells show TCR-dependent functions in vitro and are capable of in vivo anti-tumor activity. This system provides a platform to generate a large number of regenerated T-cells for clinical application and investigate human T-cell differentiation and biology.

The use of allogeneic, pluripotent stem‐cell‐derived immune cells for cancer immunotherapy has been the subject of recent clinical trials. In Japan, investigator‐initiated clinical trials will soon begin for ovarian cancer treatment using human leukocyte antigen (HLA)‐homozygous‐induced pluripotent stem cell (iPSC)‐derived anti–glypican‐3 (GPC3) chimeric antigen receptor (CAR)‐expressing natural killer/innate lymphoid cells (NK/ILC). Using pluripotent stem cells as the source for allogeneic immune cells facilitates stringent quality control of the final product, in terms of efficacy, safety and producibility. In this paper, we describe our methods for the stable, feeder‐free production of CAR‐expressing NK/ILC cells from CAR‐transduced iPSC with clinically relevant scale and materials. The average number of cells that could be differentiated from 1.8‐3.6 × 10⁶ iPSC within 7 weeks was 1.8‐4.0 × 10⁹. These cells showed stable CD45/CD7/CAR expression, effector functions of cytotoxicity and interferon gamma (IFN‐γ) production against GPC3‐expressing tumor cells. When the CAR‐NK/ILC cells were injected into a GPC3‐positive, ovarian‐tumor‐bearing, immunodeficient mouse model, we observed a significant therapeutic effect that prolonged the survival of the animals. When the cells were injected into immunodeficient mice during non–clinical safety tests, no acute systemic toxicity or tumorigenicity of the final product or residual iPSC was observed. In addition, our test results for the CAR‐NK/ILC cells generated with clinical manufacturing standards are encouraging, and these methods should accelerate the development of allogeneic pluripotent stem cell‐based immune cell cancer therapies.

Vα24 invariant natural killer T (iNKT) cells are a subset of T lymphocytes implicated in the regulation of broad immune responses. They recognize lipid antigens presented by CD1d on antigen-presenting cells and induce both innate and adaptive immune responses, which enhance effective immunity against cancer. Conversely, reduced iNKT cell numbers and function have been observed in many patients with cancer. To recover these numbers, we reprogrammed human iNKT cells to pluripotency and then re-differentiated them into regenerated iNKT cells in vitro through an IL-7/IL-15-based optimized cytokine combination. The re-differentiated iNKT cells showed proliferation and IFN-γ production in response to α-galactosylceramide, induced dendritic cell maturation and downstream activation of both cytotoxic T lymphocytes and NK cells, and exhibited NKG2D- and DNAM-1-mediated NK cell-like cytotoxicity against cancer cell lines. The immunological features of re-differentiated iNKT cells and their unlimited availability from induced pluripotent stem cells offer a potentially effective immunotherapy against cancer.