CD19 and acute lymphoblastic leukemia: The proportion of patients with high-risk cytogenetic or genetic characteristics was similar in the three groups (50.3%, 54.9% and 28.6%, respectively; P = 0.116), defined as complex karyotype, KMT2A rearranged, BCR-ABL1, Ph-like ALL, mutated TP53 or IKZF1. Among 64 patients with BCR/ABL1, 48 were in the single CD19 group, 16 were in the tandem CD19/CD22 group, and no patient was in the sequential CD19/CD22 group (P = 0.008).