CD19 and acute lymphoblastic leukemia: Multiple clinical trials (e.g., ClinicalTrials.gov numbers, NCT01626495, NCT01029366 and NCT02208362) have demonstrated that the cause or potential cause of tumor relapse in CAR-T cell immunotherapy targeting CD19 and IL-13Rα in patients with ALL and glioblastoma is the loss of antigen [13, 103].