Differentiation of BCMA-specific Induced Pluripotent Stem Cells into Rejuvenated CD8αβ+ T Cells Targeting Multiple Myeloma.

A major hurdle in adoptive T-cell therapy is cell exhaustion and failure to maintain antitumor responses. Here, we introduce an induced pluripotent stem cell (iPSC) strategy for reprogramming and revitalizing precursor exhausted B-cell maturation antigen (BCMA)-specific T cells to effectively target multiple myeloma (MM). Heteroclitic BCMA(72-80) (YLMFLLRKI)-specific CD8(+) memory cytotoxic T lymphocytes (CTL) were epigenetically reprogrammed to a pluripotent state, developed into hematopoietic progenitor cells (CD34(+) CD43(+)/CD14(-) CD235a(-)), differentiated into the T-cell lineage and evaluated for their polyfunctional activities against MM. The final T-cell products demonstrated (1) mature CD8 alpha beta(+) memory phenotype, (2) high expression of activation or costimulatory molecules (CD38, CD28, and 41BB), (3) no expression of immune checkpoint and senescence markers (CTLA4, PD1, LAG3, and TIM3; CD57), and (4) robust proliferation and polyfunctional immune responses to MM. The BCMA-specific iPSC-T cells possessed a single T-cell receptor clonotype with cognate BCMA peptide recognition and specificity for targeting MM. RNA sequencing analyses revealed distinct genome-wide shifts and a distinctive transcriptional profile in selected iPSC clones, which can develop CD8 alpha beta(+) memory T cells. This includes a repertoire of gene regulators promoting T-cell lineage development, memory CTL activation, and immune response regulation (LCK, IL7R, 4-1BB, TRAIL, GZMB, FOXF1, and ITGA1). This study highlights the potential application of iPSC technology to an adaptive T-cell therapy protocol and identifies specific transcriptional patterns that could serve as a biomarker for selection of suitable iPSC clones for the successful development of antigen-specific CD8 alpha beta(+) memory T cells to improve the outcome in patients with MM.