PD-1 expression on postinfusion CD8⁺ CAR-Ts correlates with improved clinical outcomes. (A) Individual patient PD-1 expression on CAR⁺ CD8⁺ T cells was plotted in the UMAP space; CR (top) vs PD (bottom). (B) Individual patient pre- and post-CAR-T infusion ¹⁸F-fluorodeoxyglucose–positron emission tomography (PET) scans. Preinfusion PETs were performed within 30 days of CAR-T infusion; red arrows point to site of preinfusion lymphoma lesions. Postinfusion PETs were performed 30 to 60 days after CAR-T infusion; red arrows point to areas of resolution or progression of lymphoma. (C) Representative 2D flow cytometry plot showing PD-1 expression in CR vs PD cohorts (top). Box plot showing percentages of PD-1⁺ CAR⁺ CD8⁺ T cells in CR vs PD cohorts (bottom left). KM analysis of PFS for patients with high (>57.5%) or low (<57.5%) percent of PD-1⁺ CD8⁺ CAR-Ts (bottom right); high group, n = 12; low group, n = 14. x-axis is time in days from date of CAR-T infusion. Dotted lines on box plots indicate separation lines between high and low percentages of CAR-Ts and were selected based on optimal response separation between cohorts. Because clinical outcomes were known during patient stratification, P values should be interpreted with caution. Box plots show quartiles with bands at the median; whiskers indicate 1.5 interquartile range; all observations overlaid as dots. P values are from linear regression analysis (cell type % changes) and log-rank test (PFS); ∗P < .05, ∗∗P < .01; ∗∗∗P < .001. Pt, Patient.