CD27 agonism coordinates with CD28 and 4-1BB signal to augment the efficacy of CAR-T cells in colorectal tumor

Chimeric antigen receptor T cell (CAR-T) is regarded as a promising therapy for malignancies. In our previous clinical trial targeted colorectal tumors, we found that CAR-T cells experienced poor proliferation and persistence in tumor sites. To improve the efficacy of CAR-T cells, we introduced CD27 co-stimulation signal into the established system and found that the CEA28BB27Z CAR-T cells exhibited enhanced proliferation and anti-tumor activity. Next, we demonstrated that the CEA28BB27Z CAR-T cells expressed less immune checkpoint receptors and generated more CD4(+) and CD8(+) memory stem T (T-SCM) cells compared with other CARs during constant antigen stimulation. Furthermore, our data revealed that the different combination of co-stimulation signal affected the mitochondrial dynamics of CAR-T cells, and CEA28BB27Z CAR-T cells maintained more fused mitochondrial network compared with others. Finally, we validated the superior antitumor capacity of the CEA28BB27Z CAR-T cells in xenograft models. Our findings suggest that CD27 co-stimulation signals play a key role in improving the anti-tumor efficacy of CAR-T cells.