Optimising CAR-T cell sensitivity by engineering matched extracellular sizes between CAR/antigen and CD2/CD58 adhesion complexes

Chimeric antigen receptor (CAR)-T cells exhibit low antigen sensitivity, which restricts their therapeutic efficacy and leads to patient relapses when cancer cells downregulate antigen expression. Despite the pressing need to overcome this limitation, the underlying mechanisms remain poorly understood. Here, we demonstrate that enhancing CAR sensitivity to match the sensitivity of the T-cell receptor (TCR) can be achieved by engineering matched extracellular sizes of CAR/antigen and CD2/CD58 complexes. We find that different CAR/antigen sizes, which are generated by different CAR architectures and different target antigens, require a different CD2/CD58 size to optimise sensitivity. This extracellular size-matching improves antigen engagement and co-localisation of CAR/antigen and CD2/CD58 complexes. We also find that size-matching controls co-inhibition of CARs by PD-1/PD-L1. These findngs highlight the importance of size-matching for signal integration by surface receptors and offers a new approach to tune CAR-T cell sensitivity by matching or mismatching extracellular sizes. One sentence summaryThe antigen sensitivity of CAR-T cells can be tuned to match the sensitivity of TCR-T cells by varying the relative extracellular size of CAR/antigen and CD2/CD58 complexes. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=129 SRC="FIGDIR/small/631424v1_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@17e6a55org.highwire.dtl.DTLVardef@771b38org.highwire.dtl.DTLVardef@19c3544org.highwire.dtl.DTLVardef@6d1fe1_HPS_FORMAT_FIGEXP M_FIG C_FIG