Fig. 3

The dynamic biology of CAR T-cells in the peripheral blood and tumor microenvironment. (A) Schematic diagram of CAR T-cell dynamics in different phases in two CLL patients with clinical remission for more than 10 years after the infusion of CAR T-cells. (Left) The adjacent stacked bar plots exhibit the proportion of each CAR T-cell population at different time points. (Right) In the initial stage, CD4⁺ CAR T-cells provide support to CD8⁺ CAR T-cell responses via IL-2. In the long-term remission phase, the expression of the GZMA and GZMK genes was strongly upregulated, while GZMB was not highly expressed. The persistence of Ki67^hiCD4⁺ CAR T-cells may partly be driven by healthy B cells. (B) Schematic diagram of cellular changes in bone marrow samples at different times in the TME (classified as pre-therapy, 28 days (D28) or 3 months (3M) following CAR T-cell treatment) of patients with short PFS (< 6 months) or long PFS (> 6 months). (Left) The adjacent stacked bar plots show the proportion of nontumor cells at different times. (Right) For patients with short PFS, there were terminal differentiation markers in bone marrow T cells at day 0 (D0). Monocytes/macrophages enriched with myeloid cells expressing BAFF and PD-L1 and CAR T-cells showed a more differentiated/effector phenotype at D28. At 3M, myeloma cells were increased and similar to the baseline phenotype. For patients with long PFS, the diversity of TCR was higher at D0 and increased at D28, accompanied by CAR T-cells with a more naive phenotype and enrichment of dendritic cells. CD8⁺ T cells at 3M had higher expression levels of genes associated with human bone marrow residence/retention, such as CXCR4 and CD69, and the myeloma cell phenotype was different from baseline