While the CD4+/CD8+ T‐cell ratio remained stable after transduction in CLL‐derived T cells, the ratio in ALL‐derived T cells shifted, with an increase in both CD8+ T cells (38.4% ± 4.4 vs. 58.1% ± 4.9, P < 0.01 Mann–Whitney U test) and CD8+ CAR T cells (38.4% ± 4.4 vs. 54.1% ± 5.0, P < 0.05 Mann–Whitney U test, Figure 1B,F). Here, CD4 is linked to B-cell chronic lymphocytic leukemia.