However, the group of University of Pennsylvania (UPENN)reported their results in 166 cases of ALL treated with tisagenlecleucel, in which CD19 antigenic density was tested prior to CAR T infusion and, surprisingly, no significant differences in CAR-T cell efficacy were observed in CD19-dim B-ALL cases as compared to CD19-normal or -bright B-ALL cases (50). The gene discussed is CD19; the disease is acute lymphoblastic leukemia.