CD19-TRAIL exposed equal binding capacity to the CD19+ BCP-ALL cell lines REH and NALM-6 as compared to the parental CD19-IgG1 antibody, while a HER2-TRAIL control antibody only showed significant binding due to TRAIL-R expression on the HER2-negative/CD19+ tumor cells (Figure 1E, Supplementary Figure S1B). Here, CD19 is linked to acute lymphoblastic leukemia.