Pre-clinical development and molecular characterization of an engineered type 1 regulatory T-cell product suitable for immunotherapy

Background aims: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative therapeutic approach for many hematological disorders. However, allo-HSCT is frequently accompanied by a serious side effect: graft-versus-host disease (GVHD). The clinical use of allo-HSCT is limited by the inability of current immunosuppressive regimens to adequately control GvHD without impairing the graft-versus-leukemia effect (GvL) conferred by transplanted healthy immune cells. To address this, the authors have developed an engineered type 1 regulatory T-cell product called CD4^IL-10 cells. CD4^IL-10 cells are obtained through lentiviral transduction, which delivers the human IL10 gene into purified polyclonal CD4⁺ T cells. CD4^IL-10 cells may provide an advantage over standard-of-care immunosuppressants because of the ability to suppress GvHD through continuous secretion of IL-10 and enhance the GvL effect in myeloid malignancies through targeted killing of malignant myeloid cells.

Methods: Here the authors established a production process aimed at current Good Manufacturing Practice (cGMP) production for CD4^IL-10 cells.

Results: The authors demonstrated that the CD4^IL-10 cell product maintains the suppressive and cytotoxic functions of previously described CD4^IL-10 cells. In addition, RNA sequencing analysis of CD4^IL-10 identified novel transcriptome changes, indicating that CD4^IL-10 cells primarily upregulate cytotoxicity-related genes. These include four molecules with described roles in CD8⁺ T and natural killer cell-mediated cytotoxicity: CD244, KLRD1, KLRC1 and FASLG. Finally, it was shown that CD4^IL-10 cells upregulate IL-22, which mediates wound healing and tissue repair, particularly in the gut.

Conclusions: Collectively, these results pave the way toward clinical translation of the cGMP-optimized CD4^IL-10 cell product and uncover new molecules that have a role in the clinical application of CD4^IL-10 cells.