Functional differences between CLL‐ and ALL‐derived CAR T cells in a 3D tumor microenvironment highlight CXCR4 and IL‐10 as potential modulatory targets

Despite advances in targeted therapies, treatment of chronic lymphocytic leukemia (CLL) remains challenging, highlighting the urgent need for effective new therapeutic strategies. Although chimeric antigen receptor (CAR) T-cell therapy dramatically improved outcomes in acute lymphoblastic leukemia (ALL), its efficacy in CLL is limited. We hypothesize that this disparity results from pronounced CAR T-cell exhaustion and the immunosuppressive tumor microenvironment (TME) in CLL. We utilized an autologous 3D TME co-culture model to investigate the functionality of CAR T cells derived from CLL and ALL patients within physiologically relevant conditions. Our results revealed increased exhaustion levels and diminished cytotoxicity of CAR T cells from CLL patients compared to those from ALL patients. Importantly, combining CAR T-cell treatment with interleukin-10 (IL-10) or CXCR4 blockade effectively improved cytotoxicity against CLL cells, even in stromal-protected regions within the 3D model. These findings offer insights into CAR T-cell dysfunction in CLL and support novel TME-targeted combination strategies to improve clinical outcomes.