CD19 and leukemia: CAR T cell therapy has shown impressive therapeutic effects in haematological malignancies10–13 which recently resulted in the approval of two of CD19-targeting CAR T cells by the U.S. FDA, tisagenlecleucel (Kymriah®– Novartis) in leukemia and lymphoma and axicabtagene ciloleucel (Yescarta®– Kite) in lymphoma.