Suppressive circulating M-MDSCs are associated with NDR after axi-cel. (A) Suppressive M-MDSCs are present in LBCL patient apheresis collection material used for axi-cel manufacture. Peripheral blood mononuclear cells collected by apheresis for the purpose of CAR T-cell manufacture were flow sorted for M-MDSCs (Lin^–, CD11b⁺, CD33⁺, CD15^–, CD14⁺, and HLA-DR^low) and cocultured with CD3⁺ T cells isolated from the same apheresis at varying ratios. Proliferation index was calculated, and results from 6 consecutive patients are shown. M-MDSCs were collected at baseline before LD chemotherapy and post–axi-cel (days 6, 11, 16, and 21) for LBCL, with peak indicating the highest value observed after axi-cel. (B-C) M-MDSCs shown as percentage of live cells and compared between patients experiencing DR or NDR. (D-E) M-MDSCs shown as cells per mL peripheral blood. (F) Correlation between baseline M-MDSCs and peak M-MDSCs after CAR T-cell infusion, in the peripheral blood. P values according to nonparametric t test. *P < .05; ***P < .001; ****P < .0001.