In our aggressive B cell leukemia mouse model, we had observed that within 10 days of treatment with high-affinity CD19 CAR T cells, the majority of the remaining tumor cells had become CD19neg suggesting downregulation or trogocytosis-mediated loss of CD19 in response to CD19 CAR T cell treatment (Fig. 1L, Supplementary Fig. 5). This evidence concerns the gene CD19 and neoplasm.