Generation of Tumor Antigen-Specific iPSC-Derived Thymic Emigrants Using a 3D Thymic Culture System

Abstract

SUMMARY Induced pluripotent stem cell (iPSC)-derived T cells may provide future therapies for cancer patients, but those generated by current methods, such as the OP9/DLL1 system, have shown abnormalities that pose major barriers for clinical translation. Our data indicate that these iPSC-derived CD8 single-positive T cells are more like CD4+CD8+ double-positive T cells than mature naive T cells because they display phenotypic markers of developmental arrest and an innate-like phenotype after stimulation. We developed a 3D thymic culture system to avoid these aberrant developmental fates, generating a homogeneous subset of CD8ab+ antigen-specific T cells, designated iPSC-derived thymic emigrants (iTEs). iTEs exhibit phenotypic and functional similarities to naive T cells both in vitro and in vivo, including the capacity for expansion, memory formation, and tumor suppression. These data illustrate the limitations of current methods and provide a tool to develop the next generation of iPSC-based antigen-specific immunotherapies.

Using Human Induced Pluripotent Stem Cells for the Generation of Tumor Antigen-specific T Cells

“…It has been shown that the redifferentiated T lineage cells generated from T-iPSCs by OP9/DLL1 co-culture can produce CD8 + SP T cells upon stimulation 18,19 . However, regenerated CD8 + SP T cells acquire the innate-like CD8αα homodimer 22,28 , which is an ineffective co-receptor for TCR signaling 29 . Additionally, these regenerated CD8 + SP T cells have shown strong TCR-independent cytotoxicity, making these cells unfavorable for clinical use 30 .…”

“…It has been previously reported in a murine model that T lineage cells generated from tumor antigen-specific T cell-derived hiPSCs using OP9/ DLL1 alone fail to experience conventional maturation. However, iPSC-derived immature T cells generated by the OP9/DLL1 system can mature into naïve-like T cells by further physiological thymic education in a 3D culture system 28,35 . Therefore, the protocol presented here to produce iPSC-derived immature T cells generated by the OP9/DLL1 system is vital for further attempts to generate real human tumor antigen-specific post-thymic T cells capable of long-term persistence in vivo with efficiency to treat established vascularized tumors.…”

CAR T Cells in Solid Tumors: Blueprints for Building Effective Therapies

“…In response to this need, the Restifo lab devised a new approach for generating tumor-specific T cells from iPSCs in vitro with a phenotype closer to endogenous, thymic-derived T cells ( 126 ). Their 3D thymic culture system generated tumor specific CD8αβ + naïve-like T cells that regressed melanoma and prolonged survival comparably with bona-fide naïve T cells obtained from the pmel-1 transgenic mouse spleen ( 126 ). This new approach is exciting as it may permit generation of a more robust supply of CAR-engineered naïve-like T cells to mediate long-term cures in patients whose peripheral T cells were previously dysfunctional.…”

Targeted Cellular Micropharmacies: Cells Engineered for Localized Drug Delivery

“…Most immune cells, such as T cells, B cells, NK cells, DCs, and macrophages, have been successfully generated from iPSCs for cancer immunotherapy [ 35 , 36 , 65 , 66 , 67 ]. To overcome the problem of primary T cell exhaustion and senescence due to prolonged activation and proliferation, tumor antigen-specific T cell clones are reprogrammed into iPSCs (T-iPSCs) and then successfully differentiated back into T cells again (T-iPSCs T cells) [ 37 , 68 , 69 ].…”