Exploratory Clinical Study of PD-1 Knockout Targeting MUC1 CAR-T Cells (AJMUC1) in the Treatment of MUC1-positive Advanced Breast Cancer

AJMUC1 is a genetically modified T cell therapeutic product targeting the aberrantly glycosylated MUC1 protein. CAR targeting MUC1 is introduced into autologous T cells by lentiviral vector, so that T cells expressing the receptor can recognize and kill MUC1 positive tumor cells. Preclinical studies have shown that binding of scFv targeting MUC1 to the MUC1 epitope on the surface of the target cell can induce the costimulatory CD28 and CD3ζ costimulatory domains to activate downstream signaling pathways and promote T cell activation and expansion. Activated CAR-T cells secrete a series of inflammatory cytokines and chemokines, leading to apoptosis and necrosis of target tumor cells. Following introduction of a CAR structure, the PD-1 gene of CAR-T cells is knocked out using CRISPR/Cas9, so that the CAR-T cell does not express PD-1, resulting in improved tumor killing efficiency of AJMUC due to the release of inhibition in the signaling pathway PD-1/PD-L1 in the tumor microenvironment.