Inhibiting CCR7-Regulated Cellular Senescence Enhances the Killing Ability of CD19 CAR-T Cells Against Aggressive B-Cell Lymphoma Cells

Resistance and relapse are the main challenges currently faced in the treatment of B-cell non-Hodgkin lymphoma (B-NHL) patients with CD19 Chimeric antigen receptor (CAR) T-cell therapy therapy. Therapy-induced senescence (TIS) is one of the most important mechanisms of tumor resistance. In this study, we utilized single-cell transcriptome sequencing to analyze therapy-induced lymphoma cells, revealing a distinct group of TIS characterized by memory B cell subpopulations exhibiting strong positive expression of CCR7, which is significantly elevated in TIS subpopulation compared to normal proliferating and autonomously senescent lymphoma cell subpopulations. Further analysis using immunohistochemistry, flow cytometry, and ELISA showed that CCR7 expression and serum CCL21 levels were significantly increased in patients with aggressive B-NHL who failed CAR-T therapy. Moreover, abnormally high CCR7 expression was associated with poor prognosis in B-NHL patients. In vitro, further co-culture of aggressive B-NHL cells pre-treated with the CCR7 blocking antibody CAP-100 and CD19 CAR-T cells revealed that inhibiting CCR7 could significantly suppress B-NHL cell senescence and markedly enhance the ability of CD19 CAR-T cells to kill lymphoma cells. Mechanistically, senescent B-NHL cells exhibited typical stemness characteristics in terms of immunophenotype and biological functions, including the up-regulation of stemness molecular markers, stronger colony-forming abilities, and increased invasive and migratory capabilities. Inhibiting CCL21/CCR7 signaling can block the ARHGAP18/NFKBIA pathway, reversing the enhanced stemness characteristics of B-NHL-TIS, and thereby enhancing the cytotoxicity of CD19 CAR-T cells. In summary, TIS promotes stem cell characteristics in B-NHL cells through activation of the CCR7/ARHGAP18/IKBα signaling pathway. Targeting CCR7/ARHGAP18 may overcome the intrinsic resistance of senescent B-NHL cells to CD19 CAR-T cell killing by inhibiting the acquisition and maintenance of stemness.

No relevant conflicts of interest to declare.