IL-15 and IL-21 synergy improves anti-tumor efficacy of iPSC-derived cytotoxic T cells in solid tumors.

The development of effective cellular immunotherapies for solid tumors requires the presence of robust infiltration, persistence, proliferation, and antigen-specific cytotoxicity. Here, we engineered induced pluripotent stem cell (iPSC)-derived cytotoxic T cells transduced with a chimeric antigen receptor (iCAR-T cells) and identified an optimal cytokine armoring strategy. Co-expression of interleukin-15 (IL-15) and IL-21 synergistically enhanced STAT1 phosphorylation, leading to increased transcriptional activation of the chemokine receptor CXCR3 and thereby improving tumor homing capacity. Furthermore, the engineered iCAR-T cells maintained a CD45RA-CD45RO+CCR7+CD62L+ memory T cell-like phenotype in tumors, contributing to the prolonged survival of the animal model. These findings demonstrate that cytokine synergy can be engineered into iPSC-derived T cells to overcome significant barriers in solid tumor immunotherapy, offering a scalable approach to developing next-generation off-the-shelf CAR-T therapies.