Gene expression analysis of chimeric antigen receptor-transduced T cells after antigenic stimulation
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ABSTRACT: Adoptive transfer of anti-CD19 chimeric antigen receptor (CAR)-engineered T cells has shown impressive clinical responses in patients with refractory B-cell malignancies. However, therapeutic effects of CAR-T cells targeting other hematologic malignancies and solid tumors are not yet satisfactory. Although inefficient tumor trafficking and multiple immunosuppressive molecules impede CAR-T cell effector responses, signals delivered by the current CAR constructs may still be insufficient to fully activate antitumor T cell functions. Optimal T cell activation and proliferation requires multiple signals including T cell receptor (TCR) engagement (signal 1), costimulation (signal 2), and cytokine engagement (signal 3). CAR genes developed to date contain a CD3z domain and costimulatory domain(s), but not a domain to transmit signal 3. In this study, we have developed a novel CAR construct capable of inducing cytokine signaling in an antigen-dependent manner. The new generation CD19 CAR encodes a cytoplasmic domain of IL-2RB and STAT3-binding YXXQ motif together with CD3z and CD28 domains (28-DIL2RB-z (YXXQ)). The 28-DIL2RB-z (YXXQ) CAR-T cells showed antigen-dependent JAK-STAT, especially the STAT3-mediated pathway activation, which promoted their proliferation and prevented terminal differentiation. The 28-DIL2RB-z (YXXQ) CAR-T cells demonstrated superior in vivo persistence and antileukemia effects compared with the currently used CARs in multiple tumor models.
Project description:Adoptive transfer of anti-CD19 chimeric antigen receptor (CAR)-engineered T cells has shown impressive clinical responses in patients with refractory B-cell malignancies. However, therapeutic effects of CAR-T cells targeting other hematologic malignancies and solid tumors are not yet satisfactory. Although inefficient tumor trafficking and multiple immunosuppressive molecules impede CAR-T cell effector responses, signals delivered by the current CAR constructs may still be insufficient to fully activate antitumor T cell functions. Optimal T cell activation and proliferation requires multiple signals including T cell receptor (TCR) engagement (signal 1), costimulation (signal 2), and cytokine engagement (signal 3). CAR genes developed to date contain a CD3z domain and costimulatory domain(s), but not a domain to transmit signal 3. In this study, we have developed a novel CAR construct capable of inducing cytokine signaling in an antigen-dependent manner. The new generation CD19 CAR encodes a cytoplasmic domain of IL-2RB and STAT3-binding YXXQ motif together with CD3z and CD28 domains (28-IL2RB-z (YXXQ)). The 28-IL2RB-z (YXXQ) CAR-T cells showed antigen-dependent JAK-STAT, especially the STAT3-mediated pathway activation, which promoted their proliferation and prevented terminal differentiation. The 28-IL2RB-z (YXXQ) CAR-T cells demonstrated superior in vivo persistence and antileukemia effects compared with the currently used CARs in multiple tumor models.
Project description:The adoptive transfer of chimeric antigen receptor- (CAR) modified T cells is revolutionizing the treatment of B cell malignancies and has the potential to be applied to other diseases. CARs redirect T cell specificity by linking an antigen recognition domain to T cell signaling modules comprised of CD3z to provide signal 1, and CD28 or 4-1BB to provide costimulation. CD28/CD3z and 4-1BB/CD3z CARs confer differences in effector function and cell fate that affect clinical efficacy and toxicity. These differences may result from activation of divergent transcriptional programs. To gain this insight, we analyzed changes in gene expression in stimulated and resting CD28/CD3z or 4-1BB/CD3z CAR T cells. CD28/CD3z CAR stimulation initiated more marked early transcriptional changes with greater fold increases in the expression of effector molecules including GZMB, IFNG, IL2, TNF, and IL6. Direct comparison of CD28/CD3z and 4-1BB/CD3z samples stimulated for 6 hours identified 1,673 differentially expressed genes. Of these, the memory T cell-associated genes KLF2, IL7R, and FAM65B were expressed at lower levels in CD28/CD3z CAR T cells. KLF2 and IL7R are FOXO transcription factor family targets and we found that FOXO4 expression was similarly reduced in CD28/CD3z CAR T cells. CD28/CD3z CAR stimulation induces an effector T cell-like transcriptional profile that may underlie the decreased persistence and increased risks of toxicities observed with CD28/CD3z CAR T cells in early clinical trials.
Project description:Chimeric antigen receptors (CARs) are synthetic proteins that redirect T cell specificity by linking an extracellular ligand binding domain to intracellular T cell signaling domains. CAR-expressing T (CAR-T) cells have demonstrated significant efficacy for the treatment of refractory B cell malignancies and are being evaluated as immunotherapeutic reagents for many other cancers. CAR designs are based on the fundamental principles of TCR recognition and most CARs employ the T cell-activating CD3z endodomain alongside a costimulatory domain from CD28 or 4-1BB. However, emerging data suggest that CD28/CD3z and 4-1BB/CD3z signaling modules promote divergent metabolic pathways, gene expression programs, and cell fates. To determine how CAR phosphoprotein signaling drives these disparate cell fates, we analyzed CAR ligation-induced signaling networks in primary human T cells using shotgun mass spectrometry. We isolated CD8+CD62L+ T cells from healthy donors and introduced a CD28/CD3z or 4-1BB/CD3z CAR by lentiviral transduction. Transduced T cells were purified by FACS and expanded once in vitro. When the cells returned to a resting state, CD28/CD3z or 4-1BB/CD3z CAR-T cells were stimulated for 10 or 45 minutes with magnetic microbeads coated with a monoclonal antibody specific for a 9 amino acid tag in the CAR extracellular sequence. CAR-T cells were also left unstimulated for 10 or 45 minutes to serve as controls. Altogether, 8 unique conditions were tested in an experiment and three independent experiments were performed.
Project description:Adoptive transfer of chimeric antigen receptor (CAR)-T cells is expected to become the first line of treatment for multiple malignancies, following the enormous success of anti-CD19 therapies. However, their mechanism of action is not fully understood, and clear guidelines for the design of safe and efficient receptors are missing. We hereby describe a systematic analysis of the CAR “signalosome” in human primary T cells. Two CAR designs were compared: a second-generation (PSCA2) and a third-generation (PSCA3) anti-PSCA CAR. Phosphorylation events triggered by CAR-mediated recognition of target cells were quantified by mass spectrometry.
Project description:Long-lived, self-renewing, multipotent T memory stem cells (TSCM) can trigger profound and sustained tumor regression but their rareness poses a major hurdle to their clinical application. Presently, clinically compliant procedures to generate relevant numbers of this T cell population are undefined. Here, we provide a strategy for deriving large numbers of clinical grade tumor-redirected TSCM cells starting from naïve precursors. CD8+CD62L+CD45RA+ naïve T cells enriched by streptamer-based serial positive selection were activated by CD3/CD28 engagement in the presence of IL-7, IL-21 and the glycogen synthase-3β inhibitor TWS119, and genetically engineered to express a CD19-specific chimeric antigen receptor (CD19-CAR). These conditions allowed for the generation of CD19-CAR modified TSCM cells that were phenotypically, functionally and transcriptomically equivalent to their naturally occurring counterpart. Compared with T cell products currently under clinical investigation, CD19-CAR modified TSCM cells exhibit enhanced metabolic fitness, persistence and anti-tumor activity against systemic acute lymphoblastic leukemia xenografts. Based on these findings, we have initiated a phase 1 clinical study to evaluate the activity of CD19-CAR modified TSCM in patients with B-cell malignancies refractory to prior allogeneic hematopoietic stem cell transplantation. Three healthy human blood donors provided lymphocyte-enriched apheresis blood for this study after informed consent. From all samples, total RNA was isolated using an miRNeasy Mini Kit (Qiagen), processed by Ambionâ??s WT expression kit, fragmented and labeled with a WT Terminal Labeling Kit (Affymetrix), hybridized to WT Human Gene 1.0 ST arrays (Affymetrix) and stained on a Genechip Fluidics Station 450 (Affymetrix), all according to the respective manufacturer's instructions. Samples represent exon-level and gene-level analyses.
Project description:Adoptive transfer of chimeric antigen receptor (CAR)-T cells is expected to become the first line of treatment for multiple malignancies, following the enormous success of anti-CD19 therapies. However, their mechanism of action is not fully understood, and clear guidelines for the design of safe and efficient receptors are missing. We hereby describe a systematic analysis of the CAR “interactome” in human primary T cells, which allowed us to identify molecular traits that influence CAR-T cell efficacy. Interactome analysis was based on immunoprecipitation of CARs followed by protein identification by mass spectrometry.
Project description:To characterize transfer of molecules from target cells into CAR T cells via trogocytosis we cultured NALM-6 leukemia cell line expressing a CD19-mCherry fusion protein with CAR T cells. NALM6-CD19-mCherry were loaded with heavy amino acid and cocultured with CAR T cells for 1 hour. CAR T cells were next sorted into two fractions, mCherry-positive (TrogPos), and -negative (TrogNeg). Proteomics analysis revealed the presence of targeted antigen (CD19) in the TrogPos only.
Project description:Long-lived, self-renewing, multipotent T memory stem cells (TSCM) can trigger profound and sustained tumor regression but their rareness poses a major hurdle to their clinical application. Presently, clinically compliant procedures to generate relevant numbers of this T cell population are undefined. Here, we provide a strategy for deriving large numbers of clinical grade tumor-redirected TSCM cells starting from naïve precursors. CD8+CD62L+CD45RA+ naïve T cells enriched by streptamer-based serial positive selection were activated by CD3/CD28 engagement in the presence of IL-7, IL-21 and the glycogen synthase-3β inhibitor TWS119, and genetically engineered to express a CD19-specific chimeric antigen receptor (CD19-CAR). These conditions allowed for the generation of CD19-CAR modified TSCM cells that were phenotypically, functionally and transcriptomically equivalent to their naturally occurring counterpart. Compared with T cell products currently under clinical investigation, CD19-CAR modified TSCM cells exhibit enhanced metabolic fitness, persistence and anti-tumor activity against systemic acute lymphoblastic leukemia xenografts. Based on these findings, we have initiated a phase 1 clinical study to evaluate the activity of CD19-CAR modified TSCM in patients with B-cell malignancies refractory to prior allogeneic hematopoietic stem cell transplantation.
Project description:Alternate strategies are needed for B-cell malignancy patients relapsing after CD19-targeted immunotherapy. Here, integrated cell surface proteomics and epigenetic analysis initially revealed CD72 as an optimal target for poor-prognosis MLL-rearranged B-ALL, which we further found to be expressed widely across B-cell malignancies. Using a recently-described, fully-in vitro system we selected CD72-specific nanobodies, incorporated them into CARs, and demonstrated robust activity against B-cell malignancy models, including CD19 loss. “Antigen escape profiling” modeled membrane proteome changes in the context of CD72 loss while pharmacologic SHIP1 inhibition increased CD72 surface density. We establish CD72-nanobody CAR T’s as a promising therapy for refractory B-cell malignancies.
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.