CD19 and acute lymphoblastic leukemia: In a clinical trial, 15 B-ALL children and adults were treated with an anti-CD22 CAR T cell therapy after anti-CD19 CAR T treatment, with nine cases of CD19 dim/negative relapse; five out of five patients with CD19 dim/negative relapse, who received the 1x106 CD22 CAR T cell dosage, obtained CR which demonstrates the potential usefulness of anti-CD22 CAR T cell therapy for these patients (49).