Conventional CAR T cell therapy has led to great improvements in patient survival and reducing disease burden in patients with hematological malignancies, with the pan-B cell marker CD19 most commonly targeted.2 However, it is clear from the published results of multiple clinical trials that more research is required to enhance CAR T cell efficacy against solid tumors.3–6 There are many challenges in the application of CAR T cells to solid tumors including the immunosuppressive tumor microenvironment, efficient trafficking into the tumor and extensive tumor heterogeneity (as reviewed.7 8). The gene discussed is CD19; the disease is neoplasm.