CD19 and neoplasm: The structural submodel of the nonlinear mixed-effects quantitative systems pharmacology model consisted of five species: naïve CAR-T cells (TN), central memory CAR-T cells (TCM), effector memory CAR-T cells (TEM), terminally differentiated effector CAR-T cells (TEff), and CD19+ metabolic tumor volume (CD19+) (Figure 1).