Association between CD19 levels at pretreatment or relapse and response. (A) Pretreatment CD19 H-score distribution in ZUMA-1 patients (N = 100) ordered by CD20 H-score: 90% CD19⁺, 93% CD20⁺, and 98% CD19⁺, and/or CD20⁺. CD19 and CD20 positivity was defined as H-score >5. (B) Association between pretreatment CD19 H-score with engraftment index (CAR T Peak/SPD) and clinical response. (C) Swimmer plot of relapse patients (N = 20) by CD19 status and peak CAR T-cell level. (D) Positron emission tomography scans and tumor biopsies from patient 21 at the indicated time points post–axi-cel. Brown staining shows positive signal from the respective immunohistochemistry marker with ×40 original magnification. Arrows show sites of tumor biopsy. (E) CD19 and CD20 H-scores in paired pretreatment-progression biopsies from relapsed patients (N = 18). CR, complete response; H&E, hematoxylin and eosin; PD, progressive disease; PR, partial response; SD, stable disease; SPD, sum of product of perpendicular diameters.