N1 CD4⁺ CAR-T enhance CD8⁺ CAR-T proliferation and antitumor efficacy. (A) Experiment schematic for the Raji xenograft model. (B) Flow cytometry quantification of CD4⁺ (top) and CD8⁺ (bottom) CAR-T frequencies in peripheral blood over time following injection into Raji-bearing mice. N = 10 mice per group, 2 experiments. Unpaired 2-tailed Student t test. ∗P < .05; ∗∗P < .01; ∗∗∗∗P < .001. (C) Raji tumor burden over time (left) and 34 days post–CAR-T injection (right) in mice treated with control CD8⁺ and either N1 or control CD4⁺ CAR-T, measured by intraperitoneal luciferin injection. N = 10 mice per group, 2 experiments. Mann-Whitney U test. ∗P < .05; ∗∗P < .01; ∗∗∗P < .005. (D) Experiment schematic for the JeKo-1 xenograft model. (E) Flow cytometry quantification of CD4⁺ and CD8⁺ CAR-T frequencies in peripheral blood at peak expansion 7 days after injection into JeKo-1–bearing mice. N = 5 mice per group, 1 experiment. Unpaired 2-tailed Student t test. ∗∗P < .01; ∗∗∗P < .005. (F) JeKo-1 tumor burden over time (left) and 55 days post–CAR-T injection (right) in mice treated with control CD8⁺ and either N1 or control CD4⁺ CAR-T, measured by intraperitoneal luciferin injection. N = 5 mice per group, 1 experiment. Mann-Whitney U test. ∗∗P < .01. Ctrl, control; GvHD, graft-versus-host disease.