Fig. 3
From: Challenges and strategies associated with CAR-T cell therapy in blood malignancies
Antigen-negative relapse mechanism. A. Tumor cells downregulate surface target antigen to levels below the activation threshold of CAR T cells. B. Lentiviral modification of single leukemic cell for antigen expression, masking antigen epitope from CAR T cells. C. Tumor heterogeneity leads to antigen mutation. D. Tumor cells lineage switch or receptor genetic mutations leading to lack of extracellular epitopes recognized by CAR T cells