CD19 and B-cell acute lymphoblastic leukemia: In B cell acute lymphoblastic leukemia (B-ALL) patients treated with CD19-targeted, 4-1BB-based CAR T cells, significant DNA methylation reprogramming was observed in CD8+ CD19 CAR T cells four weeks post-infusion, notably methylation of genes associated with effector function and memory potential alongside demethylation of exhaustion-associated transcription factors BATF and thymocyte-selection-associated high mobility group box factor (TOX) [100].