The interaction between pretreatment risk by LDH and CAR19 expansion classifies patients with high and low risks. (A) Pretreatment LDH strongly correlates with pretreatment ctDNA. (B) Results of lasso regression incorporating the interaction between prelymphodepletion LDH (greater or less than data set median) and prelymphodepletion CAR AUC (greater or less than data set median). Expected values selected by the lasso based on prior publications include prelymphodepletion LDH, pre-LD CRP, and bridging therapy. In addition, patients with high LDH and low CAR19 expansion (CAR^low/LDH^high) are selected as doing worse, whereas patients with low LDH and low CAR19 expansion (CAR^low/LDH^low) are selected as having improved outcomes. (C) Kaplan-Meier estimate of patients stratified by LDH and CAR expansion demonstrate superior outcomes by PFS in patients with low LDH and low CAR19 expansion.