Cholesterol efflux from C1QB-expressing macrophages is associated with resistance to chimeric antigen receptor T cell therapy in primary refractory diffuse large B cell lymphoma.

Chimeric antigen receptor T (CAR-T) cell therapy has demonstrated promising efficacy in early trials for relapsed/refractory diffuse large B cell lymphoma (DLBCL). However, its efficacy in treating primary refractory DLBCL has not been comprehensively investigated, and the underlying resistance mechanisms remain unclear. Here, we report the outcomes of a phase I, open-label, single-arm clinical trial of relmacabtagene autoleucel (relma-cel), a CD19-targeted CAR-T cell product, with safety and efficacy as primary endpoints. Among the 12 enrolled patients, 8 experienced grade 4 hematologic toxicity of treatment-emergent adverse event. No grade ≥3 cytokine release syndrome or neurotoxicity occurred. Single-cell RNA sequencing revealed an increase proportion of C1QB-expressing macrophages in patients with progressive disease before CAR-T cell therapy. Cholesterol efflux from M2 macrophages was found to inhibit CAR-T cells cytotoxicity by inducing an immunosuppressive state in CD8+ T cells, leading to their exhaustion. Possible interactions between macrophages and CD8+ T cells, mediating lipid metabolism (AFR1-FAS), immune checkpoint activation, and T cell exhaustion (LGALS9-HAVCR2, CD86-CTLA4, and NECTIN2-TIGIT) were enhanced during disease progression. These findings suggest that cholesterol efflux from macrophages may trigger CD8+ T cell exhaustion, providing a rationale for metabolic reprogramming to counteract CAR-T treatment failure. Chinadrugtrials.org.cn identifier: CTR20200376.

Transgenic expression of IL-7 regulates CAR-T cell metabolism and enhances in vivo persistence against tumor cells.

Chimeric antigen receptor (CAR) T-cell therapy has emerged as a promising novel therapeutic approach. However, primary and secondary resistance to CAR-T cell therapy is commonly encountered in various clinical trials. Despite the comprehensive studies to elucidate the mechanisms of resistance, effective resolution in clinical practice is still elusive. Inadequate persistence and subsequent loss of infused CAR-T cells are proposed major resistance mechanism associated with CAR-T cell treatment failure. Thus, we generated CAR-T cells armored with IL-7 to prolong the persistence of infused T-cells, particularly CD4 + T cells, and enhanced anti-tumor response. IL-7 increased CAR-T-cell persistence in vivo and contributed to the distinct T-cell cytotoxicity profile. Using mass cytometry (CyTOF), we further assessed the phenotypic and metabolic profiles of IL-7-secreting CAR-T cells, along with conventional CAR-T cells at the single-cell level. With in-depth analysis, we found that IL-7 maintained CAR-T cells in a less differentiated T-cell state, regulated distinct metabolic activity, and prevented CAR-T-cell exhaustion, which could be essential for CAR-T cells to maintain their metabolic fitness and anti-tumor response. Our findings thus provided clinical rationale to exploit IL-7 signaling for modulation and metabolic reprogramming of T-cell function to enhance CAR-T cell persistence and induce durable remission upon CAR-T cell therapy.