Gene expression profiles of CD4-derived (CAR4) and CD8-derived (CAR8) chimeric antigen receptor T cells after stimulation through the CAR, TCR or both receptors
Ontology highlight
ABSTRACT: Chimeric antigen receptor (CAR)-expressing T-cells induce durable remissions in patients with relapsed/refractory B-cell malignancies. CARs are artificial constructs introduced into mature T-cells conferring a second, non-MHC restricted specificity in addition to the endogenous T-cell receptor (TCR). The impact of TCR activation on CAR T-cell efficacy in vivo has important implications for clinical optimization of CAR T-cell therapy, but cannot be systematically evaluated in xenograft models. Using an immunocompetent, syngeneic murine model of CD19-targeted CAR T-cell therapy for pre-B cell ALL, we demonstrate loss of CD8 CAR T-cell mediated clearance of leukemia associated with T-cell exhaustion and apoptosis when TCR antigen is present. CD4 CAR T-cells demonstrate equivalent cytotoxicity, as compared to CD8 CAR T-cells, and in contrast, retain in vivo efficacy in the presence of TCR stimulation. Gene expression profiles confirm increased exhaustion and apoptosis of CAR8 upon dual receptor stimulation compared to CAR4, and indicate inherent differences in T-cell pathways. Chimeric antigen receptor (CAR) T cells express two activating receptors, the CAR and the endogenous T cell receptor (TCR). CAR T cells can be derived from either CD8 or CD4 T cells to generate CAR8 and CAR4 cells, respectively. In vivo, CAR8 and CAR4 cells respond differently when simultaneously stimulated through the CAR and TCR.
Project description:Chimeric antigen receptor T (CAR-T) cell therapies for B cell malignancies demonstrate high response rate and durable disease control. However, in the case of solid tumors, CAR-T cells have shown dysfunction ascribed to some intrinsic defects in CAR signaling. Here, we construct a multi-chain chimeric receptor, termed as Synthetic T Cell Receptor and Antigen Receptor (STAR), which incorporates antigen-recognition domain of antibody and engages entire CD3 signaling machinery of T cell receptor (TCR). In multiple solid tumor models, STAR-T cells prominently outperform CAR-T cells without notable toxicity. STAR triggers strong and sensitive TCR-like signaling upon antigen stimulation. We compared the transcriptional profiles of STAR/CAR/TCR-T cells after stimulation for different time points (0, 6, 24, 72 hours), in order to figure out whether signaling difference of these receptors led to distinct gene expression. Our results showd that STAR activation phencopied TCR, while CAR drove a different program, displayed as various pathways related to effector function, cytokine response and cell survival were altered.
Project description:Chimeric antigen receptor-modified (CAR) T cell therapy targeting highly expressed lineage antigens is effective for B cell malignancies. Achieving durable efficacy for hematological malignancies and extending this therapeutic approach to solid tumors will require T cell recognition and elimination of tumor cells that may express lower levels of the CAR target antigen. Realizing this goal is challenging because current approaches to CAR design are largely empiric and detailed information on CAR signaling is only beginning to emerge. Synthetic CARs typically require hundreds of molecules on the target cell to initiate signaling, whereas natural T cell receptors (TCRs) can recognize less than ten peptide-MHC (pMHC) antigen complexes. We reasoned that in depth comparison of TCR and CAR stimulation-induced signaling events in primary T cells might guide rationale adaptations to CAR design that would improve antigen sensitivity. Bi-specific T cells possessing an endogenous TCR and exogenous CAR of defined specificity were formulated from healthy HLA-B8+ Epstein-Barr virus-seropositive donors. Bi-specific T cells were stimulated with magnetic microbeads coated with recombinant TCR or CAR antigen for 10, 45, or 90 minutes. Some bi-specific T cells were also left unstimulated and harvested at each timepoint to serve as controls. Altogether, 9 unique conditions were tested in an experiment and three independent experiments were performed.
Project description:Chimeric antigen receptor (CAR) T-cells have not induced meaningful clinical responses in solid tumor indications. Loss of T-cell stemness, poor expansion capacity and exhaustion during prolonged tumor antigen exposure are major causes of CAR T-cell therapeutic resistance. scRNA-sequencing analysis of CAR T-cells from a first-in-human trial in metastatic prostate cancer identified two distinct and independently validated cell states associated with antitumor potency or lack of efficacy. Low levels of the PRDM1 gene encoding the BLIMP1 transcription factor defined highly potent TCF7+CD8+ CAR T-cells, while enrichment of TIM3+CD8+ T-cells with elevated PRDM1 expression predicted poor outcome. PRDM1 single knockout promoted TCF7-dependent CAR T-cell stemness and proliferation resulting in marginally enhanced leukemia control. However, in the setting of PRDM1 deficiency, a negative epigenetic feedback program of NFAT-driven T-cell dysfunction characterized by compensatory upregulation of NR4A3 and multiple other genes encoding exhaustion-related transcription factors hampered effector function in solid tumors. PRDM1 and NR4A3 combined ablation skewed CAR T-cell phenotypes away from TIM3+CD8+ and toward TCF7+CD8+ to counter exhaustion of tumor-infiltrating CAR T-cells and improve in vivo antitumor responses, effects that were not achieved with BLIMP1 or NR4A3 single disruption alone. These data reveal a novel molecular targeting strategy to enrich stem-like CAR T-cells resistant to exhaustion and underscore dual inhibition of PRDM1/NR4A3 expression or activity as a promising approach to advance adoptive cell immuno-oncotherapy.
Project description:Chimeric antigen receptor (CAR) T-cells have not induced meaningful clinical responses in solid tumor indications. Loss of T-cell stemness, poor expansion capacity and exhaustion during prolonged tumor antigen exposure are major causes of CAR T-cell therapeutic resistance. scRNA-sequencing analysis of CAR T-cells from a first-in-human trial in metastatic prostate cancer identified two distinct and independently validated cell states associated with antitumor potency or lack of efficacy. Low levels of the PRDM1 gene encoding the BLIMP1 transcription factor defined highly potent TCF7+CD8+ CAR T-cells, while enrichment of TIM3+CD8+ T-cells with elevated PRDM1 expression predicted poor outcome. PRDM1 single knockout promoted TCF7-dependent CAR T-cell stemness and proliferation resulting in marginally enhanced leukemia control. However, in the setting of PRDM1 deficiency, a negative epigenetic feedback program of NFAT-driven T-cell dysfunction characterized by compensatory upregulation of NR4A3 and multiple other genes encoding exhaustion-related transcription factors hampered effector function in solid tumors. PRDM1 and NR4A3 combined ablation skewed CAR T-cell phenotypes away from TIM3+CD8+ and toward TCF7+CD8+ to counter exhaustion of tumor-infiltrating CAR T-cells and improve in vivo antitumor responses, effects that were not achieved with BLIMP1 or NR4A3 single disruption alone. These data reveal a novel molecular targeting strategy to enrich stem-like CAR T-cells resistant to exhaustion and underscore dual inhibition of PRDM1/NR4A3 expression or activity as a promising approach to advance adoptive cell immuno-oncotherapy.
Project description:Targeting tumor-specific neoantigens is promising for cancer immunotherapy, yet their ultra-low expression on tumor cells poses significant challenges for T cell therapies. Here, we found that chimeric antigen receptors (CARs) exhibited 10-100 times lower sensitivity compared to T cell receptors (TCRs) when targeting p53R175H common neoantigen. To enhance CAR functionality, we introduce T cell receptor fusion construct (TRuC) and synthetic TCR and antigen receptor (STAR). Our data demonstrate that STAR, which incorporates TCR-mimic antibody fragments and complete TCR signaling machinery, optimally reproduces antigen sensitivity of TCRs. STAR outperforms both CAR and TRuC in redirecting both CD8+ and CD4+ T cells to recognize HLA class I neoantigens. In vitro, human primary T cells engineered with STAR kill multiple cancer cell lines with low neoantigen density better than CAR-T and TRuC-T cells. In tumor mouse models, STAR-T cells outperform CAR-T and TRuC-T cells in controlling neoantigen-low breast cancer and leukemia. Taken together, our findings highlight severe defects in CAR sensitivity and introduce STAR as a more sensitive synthetic receptor, providing a new framework for T cell-based immunotherapy targeting tumors with low neoantigen density.
Project description:Adoptive cell therapy, a subset of cancer immunotherapy, is collection of therapeutic approaches which aim to redirect the immune system by reprogramming patient T-cells to target antigenic molecules differentially and specifically expressed in certain cancers. One promising immunotherapy technique is CAR T-cell therapy, where cancer cells are targeted through the expression a chimeric antigen receptor (CAR), a synthetic trans- membrane receptor that functionally compensates for the T-cell receptor (TCR) but targets a tumor associated antigen on the cancer cell surface. While CAR T-cell therapy is promising with two clinically approved second-generation CARs (Kymriah and Yescarta), few studies have investigated the mechanism of signal propagation in T-cells and no studies have investigated the potential signaling response in the target cells. To gain further insight to CAR-based signaling, we stimulated third generation CD19 CAR-expressing Jurkat T-cells by co-culture with SILAC labeled CD19HI Raji B-cells and used two phosphoenrichment strategies coupled with liquid chromatography-tandem mass spec- trometry (LC-MS/MS) to detect and analyze global phosphorylation changes in both cell populations. Analysis of the phosphopeptides originating from the CD19-CAR T cells revealed an increase in many phosphorylation events necessary for canonical TCR signaling. We also observed for the first time a significant decrease in B-cell receptor- related phosphopeptide abundance in CD19HI Raji B-cells after co-culture with CD19-targetted CAR T-cells.
Project description:We report 101,326 single cell transcriptomes and surface protein landscape from the Chimeric antigen receptor-modified (CAR) T infusion products of 12 pediatric ALL patients upon CAR antigen-specific stimulation in comparison with TCR-mediated activation and controls.
Project description:Regulatory T cells (Tregs) are promising cellular therapies to induce immune tolerance in organ transplantation and autoimmune disease. The success of chimeric antigen receptor (CAR) T-cell therapy for cancer has sparked interest in using CARs to generate antigen-specific Tregs. Here, we compared CAR with endogenous T cell receptor (TCR)/CD28 activation in human Tregs. Strikingly, CAR Tregs displayed increased cytotoxicity and diminished suppression of antigen-presenting cells and effector T (Teff) cells compared with TCR/CD28 activated Tregs. RNA sequencing revealed that CAR Tregs activate Teff cell gene programs. Indeed, CAR Tregs secreted high levels of inflammatory cytokines, with a subset of FOXP3+ CAR Tregs uniquely acquiring CD40L surface expression and producing IFNγ. Interestingly, decreasing CAR antigen affinity reduced Teff cell gene expression and inflammatory cytokine production by CAR Tregs. Our findings showcase the impact of engineered receptor activation on Treg biology and support tailoring CAR constructs to Tregs for maximal therapeutic efficacy.
Project description:Chimeric antigen receptor (CAR) T cells are effective cancer therapies, particularly in indications with high, stable, and tumor-specific antigen expression. Other settings may require improved targeting sensitivity, controllable targeting selectivity, and/or additional potency enhancements to achieve robust efficacy. Here, we describe a novel receptor architecture called RESET (rapamycin-enabled, switchable endogenous T-cell receptor) that combines: (i) cell surface antigen targeting; (ii) small-molecule regulation; and (iii) the signaling proficiency and inherent sensitivity of native T-cell receptors. RESET-T cells outperformed both constitutive and drug-regulated CAR-T cells and show hallmarks of TCR activation that suggest improved fidelity to native T-cell responses. Pharmacological control then increases safety through toggling T-cell activation between active and resting states and may mitigate T- cell exhaustion caused by continuous antigen exposure. This convergence of drug-regulated targeting and natural immune receptor signal transduction may better replicate the kinetics and physiology of a classical T-cell responses and potentiate more successful and safer immunotherapies.
Project description:Chimeric antigen receptor (CAR) T cell therapy has achieved remarkable success in hematological malignancies but remains largely ineffective in solid tumors. A major factor leading to the reduced efficacy of CAR T cell therapy is T cell dysfunction, and the mechanisms mediating this dysfunction are under investigation. Here we establish a robust in vitro model to study mesothelin-redirected CAR T cell dysfunction in pancreatic cancer. Continuous antigen exposure results in hallmark features of exhaustion including reduced proliferation capacity and cytotoxicity, and severe defects in cytokine production. Here we identified a transcriptional signature at both population and single-cell levels in CAR T cells after chronic antigen exposure. In addition, TCR lineage tracing revealed a CD8+ T-to-NK-like T cell plasticity that results in reduced antigen- dependent tumor cell killing. The transcription factors SOX4 and ID3 are specifically expressed in the dysfunctional CAR NK-like T cells and are predicted to be master regulators of the dysfunction gene expression signature and of the post-thymic acquisition of an NK-like T cell fate. Finally, we identified the emergence of CAR NK-like T cells in a subset of patients after infusion of CAR T cells. The findings gleaned from this study reveal new approaches to improve the efficacy of CAR T cell therapy in solid tumors by preventing or revitalizing CAR T cell dysfunction and shed light on the plasticity of human CAR T cells.