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.

Incorporating IL7 receptor alpha signaling in the endodomain of B7H3-targeting chimeric antigen receptor T cells mediates antitumor activity in glioblastoma.

CAR-T-cell therapy has shown promise in treating hematological malignancies but faces challenges in treating solid tumors due to impaired T-cell function in the tumor microenvironment. To provide optimal T-cell activation, we developed a B7 homolog 3 protein (B7H3)-targeting CAR construct consisting of three activation signals: CD3ζ (signal 1), 41BB (signal 2), and the interleukin 7 receptor alpha (IL7Rα) cytoplasmic domain (signal 3). We generated B7H3 CAR-T cells with different lengths of the IL7Rα cytoplasmic domain, including the full length (IL7R-L), intermediate length (IL7R-M), and short length (IL7R-S) domains, and evaluated their functionality in vitro and in vivo. All the B7H3-IL7Rα CAR-T cells exhibited a less differentiated phenotype and effectively eliminated B7H3-positive glioblastoma in vitro. Superiority was found in B7H3 CAR-T cells contained the short length of the IL7Rα cytoplasmic domain. Integration of the IL7R-S cytoplasmic domain maintained pSTAT5 activation and increased T-cell proliferation while reducing activation-induced cell death. Moreover, RNA-sequencing analysis of B7H3-IL7R-S CAR-T cells after coculture with a glioblastoma cell line revealed downregulation of proapoptotic genes and upregulation of genes associated with T-cell proliferation compared with those in 2nd generation B7H3 CAR-T cells. In animal models, compared with conventional CAR-T cells, B7H3-IL7R-S CAR-T cells suppressed tumor growth and prolonged overall survival. Our study demonstrated the therapeutic potential of IL7Rα-incorporating CAR-T cells for glioblastoma treatment, suggesting a promising strategy for augmenting the effectiveness of CAR-T cell therapy.

Development of a compact bidirectional promoter-driven dual chimeric antigen receptor (CAR) construct targeting CD19 and CD20 in the Sleeping Beauty (SB) transposon system.

BACKGROUND: A bidirectional promoter-driven chimeric antigen receptor (CAR) cassette provides the simultaneous expression of two CARs, which significantly enhances dual antigen-targeted CAR T-cell therapy. METHODS: We developed a second-generation CAR directing CD19 and CD20 antigens, incorporating them in a head-to-head orientation from a bidirectional promoter using a single Sleeping Beauty transposon system. The efficacy of bidirectional promoter-driven dual CD19 and CD20 CAR T cells was determined in vitro against cell lines expressing either, or both, CD19 and CD20 antigens. In vivo antitumor activity was tested in Raji lymphoma-bearing immunodeficient NOD-scid IL2Rgammanull (NSG) mice. RESULTS: Of all tested promoters, the bidirectional EF-1α promoter optimally expressed transcripts from both sense (CD19-CAR) and antisense (GFP.CD20-CAR) directions. Superior cytotoxicity, cytokine production and antigen-specific activation were observed in vitro in the bidirectional EF-1α promoter-driven CD19/CD20 CAR T cells. In contrast, a unidirectional construct driven by the EF-1α promoter, but using self-cleaving peptide-linked CD19 and CD20 CARs, showed inferior expression and in vitro function. Treatment of mice bearing advanced Raji lymphomas with bidirectional EF-1α promoter-driven CD19/CD20 CAR T cells effectively controlled tumor growth and extended the survival of mice compared with group treated with single antigen targeted CAR T cells. CONCLUSION: The use of bidirectional promoters in a single vector offers advantages of size and robust CAR expression with the potential to expand use in other forms of gene therapies like CAR T cells.

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.

Improving cytokine-induced killer cell expansion using a gas-permeable culture method for clinical-scale production.

BACKGROUND: Cytokine-induced killer (CIK) cells are a heterogeneous group of immune cells that exert potent MHC-unrestricted cytotoxicity toward various cancer cells in both solid and hematological malignancies. OBJECTIVE: The purposes of this study were to compare the expansion and characteristics of cytokine-induced killer cells between a standard culture method and a gas-permeable culture method and to develop a clinical-scale expansion protocol for cytokine-induced killer cells using a gas-permeable culture method. METHODS: We compared the absolute cell number, fold change, cell subsets, activation markers, cytokine concentrations, and cytotoxicity toward myeloid leukemia cell lines between cytokine-induced killer cells expanded using two different culture methods. Then, we determined the ability to achieve clinical-scale expansion of cytokine-induced killer cells using the gas-permeable culture method. RESULTS: Cytokine-induced killer cells in the gas-permeable culture method group exhibited significantly better expansion but maintained similar cell subsets, activation markers, and cytotoxicity to those in the standard culture method group. In addition, we successfully manufactured cytokine-induced killer cells for clinical use using the gas-permeable culture method. We also showed the clinical efficacy of allogeneic cytokine-induced killer cells produced by the gas-permeable culture method in a patient with acute myeloid leukemia that relapsed after allogeneic hematopoietic stem cell transplantation. This patient maintained ongoing disease remission for 2 years with minimal side effects after cytokine-induced killer cell infusion. CONCLUSIONS: We successfully developed a simple and effective protocol for the ex vivo expansion of cytokine-induced killer cells using the gas-permeable culture method for clinical application.

Novel xeno-free and serum-free culturing condition to improve piggyBac transposon-based CD19 chimeric antigen receptor T-cell production and characteristics.

BACKGROUND AIMS: Chimeric antigen receptor (CAR) T cell is a novel therapy for relapse and refractory hematologic malignancy. Characteristics of CAR T cells are associated with clinical efficacy and toxicity. The type of serum supplements used during cultivation affects the immunophenotype and function of viral-based CAR T cells. This study explores the effect of serum supplements on nonviral piggyBac transposon CAR T-cell production. METHODS: PiggyBac CD19 CAR T cells were expanded in cultured conditions containing fetal bovine serum, human AB serum or xeno-free serum replacement. We evaluated the effect of different serum supplements on cell expansion, transduction efficiency, immunophenotypes and antitumor activity. RESULTS: Xeno-free serum replacement exhibited comparable CAR surface expression, cell expansion and short-term antitumor activity compared with conventional serum supplements. However, CAR T cells cultivated with xeno-free serum replacement exhibited an increased naïve/stem cell memory population and better T-cell expansion after long-term co-culture as well as during the tumor rechallenge assay. CONCLUSIONS: Our study supports the usage of xeno-free serum replacement as an alternative source of serum supplements for piggyBac-based CAR T-cell expansion.

An In Vitro Comparison of Costimulatory Domains in Chimeric Antigen Receptor T Cell for Breast Cancer Treatment.

Adoptive cellular therapy with chimeric antigen receptor (CAR) T cells has emerged as a potential novel treatment for various cancers. In this study, we have generated CAR T cells targeting mucin-1 (MUC1), which is an aberrantly glycosylated antigen overexpressed on breast cancer cells. Two different signaling domains, including CD28 and 41BB, were incorporated and directly compared the superiority of different costimulatory signals. Two different CAR MUC1 constructs were transduced into primary T cells and evaluated their characteristics and antitumor activities against MUC1+ cancer cells. CAR MUC1 T cells showed high transduction efficiency and antigen specificity toward MUC1+ cancer cell lines and primary breast cancer cells. When coculturing with target cells, the transduced cells exhibited potent antitumor activity in vitro and secrete proinflammatory cytokines. Upon antigen stimulation, incorporation of the 41BB signaling domain was able to improve T cell proliferation and reduce surface PD1 expression and the upregulation of suppressive cytokines, when compared with CAR MUC1 containing the CD28 domain. Our findings show that CAR T cell targeting MUC1 can be effective against MUC1+ breast cancer cell and support the further development of CAR MUC1 T cells containing 41BB signaling in preclinical and clinical studies of breast cancer treatment.

Potential roles of hyaluronic acid in in vivo CAR T cell reprogramming for cancer immunotherapy.

Chimeric antigen receptor (CAR) T cell therapy has recently shown unprecedented clinical efficacy for cancer treatment, particularly of hematological malignancies. However, the complex manufacturing processes that involve ex vivo genetic modification of autologous T cells limits its therapeutic application. CAR T cells generated in vivo provide a valid alternative immunotherapy, "off-the-shelf", for cancer treatment. This approach requires carriers for the delivery of CAR-encoding constructs, which are plasmid DNA or messenger RNA, to T cells for CAR expression to help eradicate the tumor. As such, there are a growing number of studies reporting gene delivery systems for in vivo CAR T cell therapy based on viral vectors and polymeric nanoparticles. Hyaluronic acid (HA) is a natural biopolymer that can serve for gene delivery, because of its inherent properties of cell recognition and internalization, as well as its biodegradability, biocompatibility, and presence of functional groups for the chemical conjugation of targeting ligands. In this review, the potential of HA in the delivery of CAR constructs is discussed on the basis of previous experience of HA-based nanoparticles for gene therapy. Furthermore, current studies on CAR carriers for in vivo-generated CAR T cells are included, giving an idea of a rational design of HA-based systems for the more efficient delivery of CAR to circulating T cells.

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.

MicroRNA-mediated metabolic reprogramming of chimeric antigen receptor T cells.

Advances made in chimeric antigen receptor (CAR) T cell therapy have revolutionized the treatment and management of certain cancers. Currently, B cell malignancies have been among the few cancers to which CAR T cells have shown persistent and resilient anti-tumor responses. A growing body of evidence suggests that the persistence of CAR T cells within patients following infusion is linked to the mitochondrial fitness of the CAR T cell, which could affect clinical outcomes. Analysis of CAR T cells from patients undergoing successful treatment has shown an increase in mitochondrial mass and fusion events, and a reduction in aerobic metabolism, highlighting the importance of mitochondria in CAR T cell function. Consequently, there has been recent interest and investment in approaches that focus on mitochondrial programming. In this regard, miRNAs are promising agents in mitochondrial reprogramming for several reasons: (1) natural and artificial miRNAs are non-immunogenic, (2) one miRNA can simultaneously modulate the expression of multiple genes within a pathway, (3) the small size of a sequence required for producing mature miRNA is ideal for use in viral vectors and (4) different precursor miRNAs (pre-miRNAs) hairpins can be incorporated into a polycistronic miRNA cluster to create a miRNA cocktail. In this perspective, we describe the latest genetic engineering strategies that can be used to achieve the optimal expression of candidate miRNAs alongside a CAR construct. In addition, we include an in silico analysis of rational candidate miRNAs that could promote the mitochondrial fitness of CAR T cells.