Optimization of anti-TIM3 chimeric antigen receptor with CD8α spacer and TNFR-based costimulation for enhanced efficacy in AML therapy.

CAR T cell therapy for AML remains limited due to the lack of a proper target without on-target off-tumor toxicity. TIM3 is a promising target due to its high expression on AML cells and absence in most normal hematopoietic cells. Previous reports have shown that each CAR component impacts CAR functionality. Here, we optimized TIM-3 targeting CAR T cells for AML therapy. We generated CARs targeting TIM3 with two different non-signaling domains: an IgG2-CH3 spacer with CD28 transmembrane domain (CH3/CD28) and a CD8α spacer with CD8α transmembrane domain (CD8/CD8), and evaluated their characteristics and function. Incorporating the non-signaling CH3/CD28 domain resulted in unstable CAR expression in anti-TIM3 CAR T cells, leading to lower surface CAR expression over time and reduced cytotoxic function compared to anti-TIM3 CARs with the CD8/CD8 domain. Both types of anti-TIM3 CAR T cells transiently exhibited fratricide, which subsided overtime, and both CAR T cells achieved substantial T cell expansion. To further optimize the design, we explored the effects of different costimulatory domains. Compared with CD28 costimulation, 4-1BB and CD27 combined with a CD8/CD8 non-signaling domain showed higher cytokine secretion, superior antitumor activity, and enhanced T-cell persistence after repeated antigen exposure. These findings emphasize the impact of the optimal design of CAR constructs that provide efficient function. In the context of anti-TIM3 CAR T cells, using a CD8α spacer and transmembrane domain with TNFR-based costimulation is a promising CAR design to improve anti-TIM3 CAR T cell function for AML therapy.

Effects of Cannabidiol on the Functions of Chimeric Antigen Receptor T Cells in Hematologic Malignancies.

Introduction: CD19-chimeric antigen receptor (CAR) T cell therapy is a promising immunotherapy for cancer treatment that has shown remarkable clinical responses, leading to approval by the FDA for relapsed and refractory B cell hematological malignancy treatment. Cannabidiol (CBD) is a nonpsychoactive cannabinoid compound that has been utilized as a palliative treatment in cancer patients due to its immunosuppressive properties. Currently, studies on using CBD during immunotherapy have gained increasing attention. However, the possible interaction between CBD and CAR T cell therapy has not been studied. Therefore, in this study, we aimed to examine the direct effects of CBD on CD19-CAR T cell function against hematologic malignancies. Materials and Methods: The cytotoxic effect of CBD was determined by a cell proliferation reagent water-soluble tatrazolium salt (WST-1) assay. CAR T cells were generated by retroviral transduction and treated with CBD at a nontoxic dose. The effect of CBD on immune characteristics, including transgene expression, T cell subset, and memory phenotype, was analyzed by flow cytometry. Proliferation, apoptosis, and cell cycle distribution were analyzed with standard methods. The effect on cytotoxic function was evaluated using degranulation assays, and antitumor activity was evaluated using flow cytometry. Results: The half-maximum inhibitory concentration (IC50) of CBD on NALM6, Raji, and T cells ranged from 16 to 22 µM. The maximum nontoxic dose of CBD that maintained cell viability at ∼100% was 8 µM. For the generation of CD19-CAR T cells, primary T cells were activated and transduced with a retroviral vector encoding CD19-CAR. CBD did not alter the surface expression or immune characteristics, including the T cell subset and memory phenotype, of CD19-CAR T cells. However, CBD suppressed CD19-CAR T cell proliferation by inducing apoptosis, as evidenced by an increase in the proportion of cells in the Sub-G1 phase in cell cycle arrest. However, the antitumor activity and cytokine secretion of CD19-CAR T cells were not altered by exposure to CBD in this study. Conclusions: In this study, a nontoxic dose of CBD affected CD19-CAR T cell proliferation but not its immune characteristics or cytotoxic function.

Triple-negative breast cancer influences a mixed M1/M2 macrophage phenotype associated with tumor aggressiveness.

Triple-negative breast cancer (TNBC) is characterized by excessive accumulation of tumor-infiltrating immune cells, including tumor-associated macrophages (TAMs). TAMs consist of a heterogeneous population with high plasticity and are associated with tumor aggressiveness and poor prognosis. Moreover, breast cancer cells can secrete factors that influence TAM polarization. Therefore, this study aimed to evaluate the crosstalk between cancer cells and macrophages in the context of TNBC. Cytokine-polarized M2 macrophage were used as control. Distinct from the classical M2 macrophage, TAMs generated from TNBC-conditioned media upregulated both M1- and M2-associated genes, and secreted both the anti-inflammatory cytokine interleukin IL-10 and the proinflammatory cytokine IL-6 and tumor necrosis factor- α. Theses TNBC-induced TAMs exert aggressive behavior of TNBC cells. Consistently, TCGA and MTABRIC analyses of human breast cancer revealed upregulation of M1- associated genes in TNBC comparing with non-TNBC. Among these M1-associated genes, CXCL10 and IL1B were revealed to be independent prognostic factors for disease progression. In conclusion, TNBC cells induce macrophage polarization with a mixture of M1 and M2 phenotypes. These cancer-induced TAMs further enhance tumor cell growth and aggressiveness.