Resistance to CAR T-cell therapies includes loss of CD19 antigen, new mutations or post-translational modifications in CD19, defective manufacturing of T cells, insufficient T cell expansion, changes to the cytokine milieu or functioning of CD4/CD8, upregulation of negative regulatory receptors, interaction between the tumor microenvironment on T-cell expansion, and impaired death receptor signaling (91, 92). This evidence concerns the gene CD19 and neoplasm.