CD19 and acute lymphoblastic leukemia: Interestingly, a recent existing finding demonstrates that human CAR-T cells polarized and expanded under a Th9-culture condition (T9 CAR-T) display stronger anti-tumor activity against established CD19-expressing human ALL or GPC3-expressing liver carcinoma in vivo compared to the classical IL-2-polarized (T1) CAR-T cells [107].