Armoured CAR Tregs with PD1 promoter-driven IL-10 have enhanced suppressive function

The potency of regulatory T cell (Treg) therapy has been transformed through use of chimeric antigen receptors (CAR). However, to date, CAR Treg therapy has not achieved long-lasting tolerance in mouse models, suggesting that additional engineering is required to unlock the full potential of these cells. We previously found that human Tregs produce minimal amounts of IL-10 and have a limited capacity to control innate immunity in comparison to type I regulatory (Tr1) cells. Seeking to create “hybrid” CAR Tregs that were engineered with Tr1-like properties, we examined whether the PDCD1 locus could be exploited to endow Tregs with the ability to secrete high levels of IL-10 in a CAR-regulated manner. Human Tregs, Tr1s, and conventional T cells (Tconvs) were engineered with an HLA-A2-specific CAR. CAR-Tregs were then edited via homology directed repair to knock-out PD1 and introduce IL10 under control of the PDCD1 promoter. All cell types were stimulated for 16 hours via their CAR, then harvested for RNA sequencing analysis.