Gene Summary

Gene:CARS; cysteinyl-tRNA synthetase
Aliases: CARS1, CYSRS, MGC:11246
Summary:This gene encodes a class 1 aminoacyl-tRNA synthetase, cysteinyl-tRNA synthetase. Each of the twenty aminoacyl-tRNA synthetases catalyzes the aminoacylation of a specific tRNA or tRNA isoaccepting family with the cognate amino acid. This gene is one of several located near the imprinted gene domain on chromosome 11p15.5, an important tumor-suppressor gene region. Alterations in this region have been associated with Beckwith-Wiedemann syndrome, Wilms tumor, rhabdomyosarcoma, adrenocortical carcinoma, and lung, ovarian and breast cancers. Alternative splicing of this gene results in multiple transcript variants. [provided by RefSeq, Aug 2010]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:cysteine--tRNA ligase, cytoplasmic
Source:NCBIAccessed: 27 August, 2015


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 27 August 2015 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Tumor Escape
  • Genetic Engineering
  • Adolescents
  • Immunotherapy
  • Recombinant Fusion Proteins
  • Chromosome 11
  • Gene Transfer Techniques
  • Adoptive Transfer
  • Neoplasm Proteins
  • Membrane Proteins
  • Genetic Therapy
  • Childhood Cancer
  • T-Lymphocytes, Cytotoxic
  • Immunophenotyping
  • Base Sequence
  • Mice, Inbred NOD
  • Ubiquitin-Protein Ligases
  • Young Adult
  • Antigens, CD3
  • Oncogene Fusion Proteins
  • Cell Line
  • B-Lymphocytes
  • ZAP-70 Protein-Tyrosine Kinase
  • Monoclonal Antibodies
  • Prostate Cancer
  • T-Lymphocytes
  • Antigens, CD19
  • Molecular Targeted Therapy
  • Cell Proliferation
  • Cytotoxicity, Immunologic
  • Receptors, Antigen
  • Antigens, CD20
  • T-Cell Antigen Receptors
  • Lymphocyte Activation
  • Genetic Vectors
  • Immunotherapy, Adoptive
  • Xenograft Models
  • Precursor B-Cell Lymphoblastic Leukemia-Lymphoma
  • Ovarian Cancer
  • Antigens, CD28
  • Breast Cancer
Tag cloud generated 27 August, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: CARS (cancer-related)

Ninomiya S, Narala N, Huye L, et al.
Tumor indoleamine 2,3-dioxygenase (IDO) inhibits CD19-CAR T cells and is downregulated by lymphodepleting drugs.
Blood. 2015; 125(25):3905-16 [PubMed] Article available free on PMC after 18/06/2016 Related Publications
Although T cells expressing CD19-specific chimeric antigen receptors (CARs) are a promising new therapy for B-cell malignancies, objective responses are observed at lower frequencies in patients with lymphoma than in those with acute B-cell leukemia. We postulated that the tumor microenvironment suppresses CAR-expressing T cells (CARTs) through the activity of indoleamine 2,3-dioxygenase (IDO), an intracellular enzyme that converts tryptophan into metabolites that inhibit T -: cell activity. To investigate the effects of tumor IDO on CD19-CART therapy, we used a xenograft lymphoma model expressing IDO as a transgene. CD19-CARTs inhibited IDO-negative tumor growth but had no effect on IDO-positive tumors. An IDO inhibitor (1-methyl-tryptophan) restored IDO-positive tumor control. Moreover, tryptophan metabolites inhibited interleukin (IL)-2-, IL-7-, and IL-15-dependent expansion of CARTs; diminished their proliferation, cytotoxicity, and cytokine secretion in vitro in response to CD19 recognition; and increased their apoptosis. Inhibition of CD19-CARTs was not mitigated by the incorporation of costimulatory domains, such as 4-1BB, into the CD19-CAR. Finally, we found that fludarabine and cyclophosphamide, frequently used before CART administration, downregulated IDO expression in lymphoma cells and improved the antitumor activity of CD19-CART in vivo. Because tumor IDO inhibits CD19-CARTs, antagonizing this enzyme may benefit CD19-CART therapy.

Bouhassira DC, Thompson JJ, Davila ML
Using gene therapy to manipulate the immune system in the fight against B-cell leukemias.
Expert Opin Biol Ther. 2015; 15(3):403-16 [PubMed] Related Publications
INTRODUCTION: Over 20 years ago, chimeric antigen receptors (CARs) were created to endow T cells with new antigen-specificity and create a therapy that could eradicate cancer and provide life-long protection against recurrence. Steady progress has led to significant improvements with CAR design and CAR T-cell production, allowing evaluation of CAR T cells in patients. The initial trials have targeted CD19, which is expressed on normal and malignant B cells.
AREAS COVERED: We review data from trials for patients with chronic lymphocytic leukemia (CLL) and B-cell acute lymphoblastic leukemia (B-ALL). In addition, we discuss the on-target toxicities, B-cell aplasia and cytokine release syndrome (CRS), which is uniquely associated with T-cell immunotherapies.
EXPERT OPINION: We compare the results when targeting the same antigen in CLL or B-ALL and speculate on reasons for outcome differences and future directions to enhance outcomes. Furthermore, the dramatic results targeting B-ALL require further analysis in Phase II trials, and we discuss important components of these future trials. We also suggest a management scheme for CRS. The next several years will be critical and may lead to the first clinical indication of a gene-engineered cell therapy for cancer.

Watanabe K, Terakura S, Martens AC, et al.
Target antigen density governs the efficacy of anti-CD20-CD28-CD3 ζ chimeric antigen receptor-modified effector CD8+ T cells.
J Immunol. 2015; 194(3):911-20 [PubMed] Related Publications
The effectiveness of chimeric Ag receptor (CAR)-transduced T (CAR-T) cells has been attributed to supraphysiological signaling through CARs. Second- and later-generation CARs simultaneously transmit costimulatory signals with CD3ζ signals upon ligation, but may lead to severe adverse effects owing to the recognition of minimal Ag expression outside the target tumor. Currently, the threshold target Ag density for CAR-T cell lysis and further activation, including cytokine production, has not yet been investigated in detail. Therefore, we determined the threshold target Ag density required to induce CAR-T cell responses using novel anti-CD20 CAR-T cells with a CD28 intracellular domain and a CD20-transduced CEM cell model. The newly developed CD20CAR-T cells demonstrated Ag-specific lysis and cytokine secretion, which was a reasonable level as a second-generation CAR. For lytic activity, the threshold Ag density was determined to be ∼200 molecules per target cell, whereas the Ag density required for cytokine production of CAR-T cells was ∼10-fold higher, at a few thousand per target cell. CD20CAR-T cells responded efficiently to CD20-downregulated lymphoma and leukemia targets, including rituximab- or ofatumumab-refractory primary chronic lymphocytic leukemia cells. Despite the potential influence of the structure, localization, and binding affinity of the CAR/Ag, the threshold determined may be used for target Ag selection. An Ag density below the threshold may not result in adverse effects, whereas that above the threshold may be sufficient for practical effectiveness. CD20CAR-T cells also demonstrated significant lytic activity against CD20-downregulated tumor cells and may exhibit effectiveness for CD20-positive lymphoid malignancies.

Douer D
Will novel agents for ALL finally change the natural history?
Best Pract Res Clin Haematol. 2014 Sep-Dec; 27(3-4):247-58 [PubMed] Related Publications
Pediatric acute lymphoblastic leukemia (ALL) cure rates have markedly improved over the past years to approximately 85%, but remain at 40%-50% in adults. Redefining current adult chemotherapy regimens is likely to improve the natural course of the disease, but new agents are needed. Immunotherapy approaches for pre-B ALL are in the forefront of research on novel agents; in particular, advances are being made in manipulating autologous T cells either by infusion of a bifunctional antibody (eg, blinatumomab) or by ex vivo genetic modification of chimeric antigen receptors (CARs). The natural course of Philadelphia positive ALL has already improved by targeting ABL/BCR1. Other mutated genes are being discovered and novel small molecules that target their products are being studied in clinical trials. Finally, ALL is a heterogeneous disease and novel agents are likely to impact the natural course of smaller populations of biologically defined ALL subtypes.

Caruana I, Diaconu I, Dotti G
From monoclonal antibodies to chimeric antigen receptors for the treatment of human malignancies.
Semin Oncol. 2014; 41(5):661-6 [PubMed] Article available free on PMC after 01/10/2015 Related Publications
Monoclonal antibodies (mAbs) and their directly derived cell-based application known as chimeric antigen receptors (CARs) ensue from the need to develop novel therapeutic strategies that retain high anti-tumor activity, but carry reduced toxicity compared to conventional chemo- and radiotherapies. In this concise review article, we will summarize the application of antibodies designed to target antigens expressed by tumor cells, and the transition from these antibodies to the generation of CARs.

Reiche K, Kasack K, Schreiber S, et al.
Long non-coding RNAs differentially expressed between normal versus primary breast tumor tissues disclose converse changes to breast cancer-related protein-coding genes.
PLoS One. 2014; 9(9):e106076 [PubMed] Article available free on PMC after 01/10/2015 Related Publications
Breast cancer, the second leading cause of cancer death in women, is a highly heterogeneous disease, characterized by distinct genomic and transcriptomic profiles. Transcriptome analyses prevalently assessed protein-coding genes; however, the majority of the mammalian genome is expressed in numerous non-coding transcripts. Emerging evidence supports that many of these non-coding RNAs are specifically expressed during development, tumorigenesis, and metastasis. The focus of this study was to investigate the expression features and molecular characteristics of long non-coding RNAs (lncRNAs) in breast cancer. We investigated 26 breast tumor and 5 normal tissue samples utilizing a custom expression microarray enclosing probes for mRNAs as well as novel and previously identified lncRNAs. We identified more than 19,000 unique regions significantly differentially expressed between normal versus breast tumor tissue, half of these regions were non-coding without any evidence for functional open reading frames or sequence similarity to known proteins. The identified non-coding regions were primarily located in introns (53%) or in the intergenic space (33%), frequently orientated in antisense-direction of protein-coding genes (14%), and commonly distributed at promoter-, transcription factor binding-, or enhancer-sites. Analyzing the most diverse mRNA breast cancer subtypes Basal-like versus Luminal A and B resulted in 3,025 significantly differentially expressed unique loci, including 682 (23%) for non-coding transcripts. A notable number of differentially expressed protein-coding genes displayed non-synonymous expression changes compared to their nearest differentially expressed lncRNA, including an antisense lncRNA strongly anticorrelated to the mRNA coding for histone deacetylase 3 (HDAC3), which was investigated in more detail. Previously identified chromatin-associated lncRNAs (CARs) were predominantly downregulated in breast tumor samples, including CARs located in the protein-coding genes for CALD1, FTX, and HNRNPH1. In conclusion, a number of differentially expressed lncRNAs have been identified with relation to cancer-related protein-coding genes.

Mata M, Vera JF, Gerken C, et al.
Toward immunotherapy with redirected T cells in a large animal model: ex vivo activation, expansion, and genetic modification of canine T cells.
J Immunother. 2014; 37(8):407-15 [PubMed] Article available free on PMC after 01/10/2015 Related Publications
Adoptive transfer of T cells expressing chimeric antigen receptors (CARs) has shown promising antitumor activity in early phase clinical studies, especially for hematological malignancies. However, most preclinical models do not reliably mimic human disease. We reasoned that developing an adoptive T-cell therapy approach for spontaneous osteosarcoma (OS) occurring in dogs would more closely reproduce the condition in human cancer. To generate CAR-expressing canine T cells, we developed expansion and transduction protocols that allow for the generation of sufficient numbers of CAR-expressing canine T cells for future clinical studies in dogs within 2 weeks of ex vivo culture. To evaluate the functionality of CAR-expressing canine T cells, we targeted HER2(+) OS. We demonstrate that canine OS is positive for HER2, and that canine T cells expressing a HER2-specific CAR with human-derived transmembrane and CD28.ζ signaling domains recognize and kill HER2(+) canine OS cell lines in an antigen-dependent manner. To reduce the potential immunogenicity of the CAR, we evaluated a CAR with canine-derived transmembrane and signaling domains, and found no functional difference between human and canine CARs. Hence, we have successfully developed a strategy to generate CAR-expressing canine T cells for future preclinical studies in dogs. Testing T-cell therapies in an immunocompetent, outbred animal model may improve our ability to predict their safety and efficacy before conducting studies in humans.

Guerrero AD, Moyes JS, Cooper LJ
The human application of gene therapy to re-program T-cell specificity using chimeric antigen receptors.
Chin J Cancer. 2014; 33(9):421-33 [PubMed] Article available free on PMC after 01/10/2015 Related Publications
The adoptive transfer of T cells is a promising approach to treat cancers. Primary human T cells can be modified using viral and non-viral vectors to promote the specific targeting of cancer cells via the introduction of exogenous T-cell receptors (TCRs) or chimeric antigen receptors (CARs). This gene transfer displays the potential to increase the specificity and potency of the anticancer response while decreasing the systemic adverse effects that arise from conventional treatments that target both cancerous and healthy cells. This review highlights the generation of clinical-grade T cells expressing CARs for immunotherapy, the use of these cells to target B-cell malignancies and, particularly, the first clinical trials deploying the Sleeping Beauty gene transfer system, which engineers T cells to target CD19+ leukemia and non-Hodgkin's lymphoma.

Heczey A, Liu D, Tian G, et al.
Invariant NKT cells with chimeric antigen receptor provide a novel platform for safe and effective cancer immunotherapy.
Blood. 2014; 124(18):2824-33 [PubMed] Article available free on PMC after 30/10/2015 Related Publications
Advances in the design of chimeric antigen receptors (CARs) have improved the antitumor efficacy of redirected T cells. However, functional heterogeneity of CAR T cells limits their therapeutic potential and is associated with toxicity. We proposed that CAR expression in Vα24-invariant natural killer T (NKT) cells can build on the natural antitumor properties of these cells while their restriction by monomorphic CD1d limits toxicity. Primary human NKT cells were engineered to express a CAR against the GD2 ganglioside (CAR.GD2), which is highly expressed by neuroblastoma (NB). We compared CAR.GD2 constructs that encoded the CD3ζ chain alone, with CD28, 4-1BB, or CD28 and 4-1BB costimulatory endodomains. CAR.GD2 expression rendered NKT cells highly cytotoxic against NB cells without affecting their CD1d-dependent reactivity. We observed a striking T helper 1-like polarization of NKT cells by 4-1BB-containing CARs. Importantly, expression of both CD28 and 4-1BB endodomains in the CAR.GD2 enhanced in vivo persistence of NKT cells. These CAR.GD2 NKT cells effectively localized to the tumor site had potent antitumor activity, and repeat injections significantly improved the long-term survival of mice with metastatic NB. Unlike T cells, CAR.GD2 NKT cells did not induce graft-versus-host disease. These results establish the potential of NKT cells to serve as a safe and effective platform for CAR-directed cancer immunotherapy.

Qasim W, Thrasher AJ
Progress and prospects for engineered T cell therapies.
Br J Haematol. 2014; 166(6):818-29 [PubMed] Article available free on PMC after 30/10/2015 Related Publications
Proof-of-concept studies have demonstrated the therapeutic potential of engineered T cells. Transfer of recombinant antigen-specific T cell receptors (TCR) and chimaeric antigen receptors (CARs) against tumour and viral antigens are under investigation by multiple approaches, including viral- and nonviral-mediated gene transfer into both autologous and allogeneic T cell populations. There have been notable successes recently using viral vector-mediated transfer of CARs specific for B cell antigens, but also reports of anticipated and unanticipated complications in these and other studies. We review progress in this promising area of cellular therapy, and consider developments in antigen receptor therapies including the application of emerging gene-editing technologies.

Krebs S, Chow KK, Yi Z, et al.
T cells redirected to interleukin-13Rα2 with interleukin-13 mutein--chimeric antigen receptors have anti-glioma activity but also recognize interleukin-13Rα1.
Cytotherapy. 2014; 16(8):1121-31 [PubMed] Article available free on PMC after 30/10/2015 Related Publications
BACKGROUND AIMS: Outcomes for patients with glioblastoma remain poor despite aggressive multimodal therapy. Immunotherapy with genetically modified T cells expressing chimeric antigen receptors (CARs) targeting interleukin (IL) 13Rα2, human epidermal growth factor receptor 2, epidermal growth factor variant III or erythropoietin-producing hepatocellular carcinoma A2 has shown promise for the treatment of glioma in preclinical models. On the basis of IL13Rα2 immunotoxins that contain IL13 molecules with one or two amino acid substitutions (IL13 muteins) to confer specificity to IL13Rα2, investigators have constructed CARS with IL13 muteins as antigen-binding domains. Whereas the specificity of IL13 muteins in the context of immunotoxins is well characterized, limited information is available for CAR T cells.
METHODS: We constructed four second-generation CARs with IL13 muteins with one or two amino acid substitutions, and evaluated the effector function of IL13-mutein CAR T cells in vitro and in vivo.
RESULTS: T cells expressing all four CARs recognized IL13Rα1 or IL13Rα2 recombinant protein in contrast to control protein (IL4R) as judged by interferon-γ production. IL13 protein produced significantly more IL2, indicating that IL13 mutein-CAR T cells have a higher affinity to IL13Rα2 than to IL13Rα1. In cytotoxicity assays, CAR T cells killed IL13Rα1- and/or IL13Rα2-positive cells in contrast to IL13Rα1- and IL13Rα2-negative controls. Although we observed no significant differences between IL13 mutein-CAR T cells in vitro, only T cells expressing IL13 mutein-CARs with an E13K amino acid substitution had anti-tumor activity in vivo that resulted in a survival advantage of treated animals.
CONCLUSIONS: Our study highlights that the specificity/avidity of ligands is context-dependent and that evaluating CAR T cells in preclinical animal model is critical to assess their potential benefit.

Abate-Daga D, Lagisetty KH, Tran E, et al.
A novel chimeric antigen receptor against prostate stem cell antigen mediates tumor destruction in a humanized mouse model of pancreatic cancer.
Hum Gene Ther. 2014; 25(12):1003-12 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Despite advances in the understanding of its molecular pathophysiology, pancreatic cancer remains largely incurable, highlighting the need for novel therapies. We developed a chimeric antigen receptor (CAR) specific for prostate stem cell antigen (PSCA), a glycoprotein that is overexpressed in pancreatic cancer starting at early stages of malignant transformation. To optimize the CAR design, we used antigen-recognition domains derived from mouse or human antibodies, and intracellular signaling domains containing one or two T cell costimulatory elements, in addition to CD3zeta. Comparing multiple constructs established that the CAR based on human monoclonal antibody Ha1-4.117 had the greatest reactivity in vitro. To further analyze this CAR, we developed a human pancreatic cancer xenograft model and adoptively transferred CAR-engineered T cells into animals with established tumors. CAR-engineered human lymphocytes induced significant antitumor activity, and unlike what has been described for other CARs, a second-generation CAR (containing CD28 cosignaling domain) induced a more potent antitumor effect than a third-generation CAR (containing CD28 and 41BB cosignaling domains). While our results provide evidence to support PSCA as a target antigen for CAR-based immunotherapy of pancreatic cancer, the expression of PSCA on selected normal tissues could be a source of limiting toxicity.

Kakarla S, Gottschalk S
CAR T cells for solid tumors: armed and ready to go?
Cancer J. 2014 Mar-Apr; 20(2):151-5 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Chimeric antigen receptor (CAR) T cells face a unique set of challenges in the context of solid tumors. To induce a favorable clinical outcome, CAR T cells have to surmount a series of increasingly arduous tasks. First, they have to be made specific for an antigen whose expression clearly demarcates tumor from normal tissue. Then, they must be able to home and penetrate the desmoplastic stroma that surrounds the tumor. Once within the tumor, they must expand, persist, and mediate cytotoxicity in a hostile milieu largely composed of immunosuppressive modulators. Whereas a seemingly herculean task, all of the aforementioned requirements can potentially be met effectively through both intrinsic and/or extrinsic modifications of CAR T cells. In this review, we delineate the barriers imposed by solid tumors on CARs and strategies that have and should be undertaken to improve therapeutic response.

Ramos CA, Savoldo B, Dotti G
CD19-CAR trials.
Cancer J. 2014 Mar-Apr; 20(2):112-8 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
CD19 is a B-lineage-specific transmembrane glycoprotein, the expression of which is maintained on more than 95% B-cell malignancies. This strict lineage restriction makes CD19 an ideal target for immune therapies using chimeric antigen receptors (CARs). Here, we review published phase 1 trials of T cells expressing CARs targeting CD19 and describe briefly the biological questions that they addressed. All patients treated in these trials had relapsed B-cell malignancies, which in many cases were chemorefractory. Nonetheless, major responses have been observed, especially in patients with chronic lymphocytic leukemia and acute lymphoblastic leukemia. Many of these responses were accompanied by a systemic inflammatory reaction syndrome that could be life threatening but was almost always reversible with adequate medical management. Given their remarkable activity, CD19-CAR T cells are likely to be quickly incorporated into the management of B-cell neoplasms; these cells have become the paradigm for similar strategies targeting other cancers.

He Y, Gong J, Wang Y, et al.
Potentially functional polymorphisms in aminoacyl-tRNA synthetases genes are associated with breast cancer risk in a Chinese population.
Mol Carcinog. 2015; 54(7):577-83 [PubMed] Related Publications
Aminoacyl-tRNA synthetases (ARSs) are responsible for cellular protein synthesis and cell viability involving in various process of tumorigenesis. We hypothesized that genetic variants in core ARSs genes may play an important role in the development of breast cancer. Thus, we conducted a case-control study including 1064 breast cancer cases and 1073 cancer-free controls to evaluate the associations of 28 potentially functional polymorphisms in 12 core ARSs genes (AARS, CARS, EPRS, HARS, KARS, LARS, MARS, QARS, RARS, VARS, WARS, and YARS) with breast cancer risk. We found significant associations with the risk of breast cancer for rs34087264 in AARS [odds ratio (OR) = 1.15, 95% confidence interval (CI) = 1.01-1.31], rs801186 in HARS (OR = 1.29, 95% CI = 1.08-1.54), rs193466 in RARS (OR = 1.17, 95% CI = 1.02-1.35), and rs2273802 in WARS (OR = 1.14, 95% CI = 1.01-1.30). We further observed significant interactions between rs2273802 and age at the first live birth (P = 0.041), and between rs801186 and age on breast cancer risk (P = 0.018). Combined analysis of these four SNPs showed a significant allele-dosage association between the number of risk alleles and breast cancer risk (Ptrend  = 2.00 × 10(-4) ). Compared with individuals with "0-2" risk alleles, those carrying "3," "4," or "5 or more" risk alleles had a 1.32 (95% CI = 1.07-1.64), 1.48 (95% CI = 1.45-1.91), or 1.60 folds (95% CI = 1.06-2.41) risk of breast cancer, respectively. These findings indicate that genetic variants in core ARSs genes may modify the individual susceptibility to breast cancer in Chinese population.

Budde LE, Berger C, Lin Y, et al.
Combining a CD20 chimeric antigen receptor and an inducible caspase 9 suicide switch to improve the efficacy and safety of T cell adoptive immunotherapy for lymphoma.
PLoS One. 2013; 8(12):e82742 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Modification of T cells with chimeric antigen receptors (CAR) has emerged as a promising treatment modality for human malignancies. Integration of co-stimulatory domains into CARs can augment the activation and function of genetically targeted T cells against tumors. However, the potential for insertional mutagenesis and toxicities due to the infused cells have made development of safe methods for removing transferred cells an important consideration. We have genetically modified human T cells with a lentiviral vector to express a CD20-CAR containing both CD28 and CD137 co-stimulatory domains, a "suicide gene" relying on inducible activation of caspase 9 (iC9), and a truncated CD19 selectable marker. Rapid expansion (2000 fold) of the transduced T cells was achieved in 28 days after stimulation with artificial antigen presenting cells. Transduced T cells exhibited effective CD20-specific cytotoxic activity in vitro and in a mouse xenograft tumor model. Activation of the iC9 suicide switch resulted in efficient removal of transduced T cells both in vitro and in vivo. Our work demonstrates the feasibility and promise of this approach for treating CD20(+) malignancies in a safe and more efficient manner. A phase I clinical trial using this approach in patients with relapsed indolent B-NHL is planned.

Heczey A, Louis CU
Advances in chimeric antigen receptor immunotherapy for neuroblastoma.
Discov Med. 2013; 16(90):287-94 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Neuroblastoma (NBL) is the most common extracranial pediatric solid tumor and has heterogeneous biology and behavior. Patients with high-risk disease have poor prognosis despite complex multimodal therapy; therefore, novel curative approaches are needed. Immunotherapy is a novel therapeutic approach that harnesses the inherent activity of the immune system to control and eliminate malignant cells. One form of immunotherapy uses chimeric antigen receptors (CAR) to target tumor-associated antigens. CARs are derived from the antigen-binding domain of a monoclonal antibody (MAb) coupled with the intracellular signaling portion of the T cell receptor. CARs can combine the specificity and effectiveness of MAbs with the active bio-distribution, direct cytotoxicity, and long-term persistence of T cells. NBL provides an attractive target for CAR immunotherapy as many of its tumor-associated antigens are not expressed at significant levels on normal tissues, thus decreasing potential treatment related toxicity. Two previous clinical trials utilizing L1-cell adhesion molecule (L1-CAM) and disialoganglioside (GD2) specific CARs (GD2-CAR) have demonstrated safety and anti-tumor efficacy in heavily pretreated relapsed/refractory neuroblastoma patients. Based on these promising results and on improved techniques that can further potentiate CAR therapies, two clinical trials are currently investigating the use of GD2-CARs in children with NBL. Several approaches may further enhance anti-tumor activity and persistence of CAR modified cells, and if these can be safely translated into the clinic, CAR-based immunotherapy could become a viable adjunct or potential alternative to conventional treatment options for patients with NBL.

Gschweng E, De Oliveira S, Kohn DB
Hematopoietic stem cells for cancer immunotherapy.
Immunol Rev. 2014; 257(1):237-49 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Hematopoietic stem cells (HSCs) provide an attractive target for immunotherapy of cancer and leukemia by the introduction of genes encoding T-cell receptors (TCRs) or chimeric antigen receptors (CARs) directed against tumor-associated antigens. HSCs engraft for long-term blood cell production and could provide a continuous source of targeted anti-cancer effector cells to sustain remissions. T cells produced de novo from HSCs may continuously replenish anti-tumor T cells that have become anergic or exhausted from ex vivo expansion or exposure to the intratumoral microenvironment. In addition, transgenic T cells produced in vivo undergo allelic exclusion, preventing co-expression of an endogenous TCR that could mis-pair with the introduced TCR chains and blunt activity or even cause off-target reactivity. CAR-engineered HSCs may produce myeloid and natural killer cells in addition to T cells expressing the CAR, providing broader anti-tumor activity that arises quickly after transplant and does not solely require de novo thymopoiesis. Use of TCR- or CAR-engineered HSCs would likely require cytoreductive conditioning to achieve long-term engraftment, and this approach may be used in clinical settings where autologous HSC transplant is being performed to add a graft-versus-tumor effect. Results of experimental and preclinical studies performed to date are reviewed.

Singh H, Huls H, Kebriaei P, Cooper LJ
A new approach to gene therapy using Sleeping Beauty to genetically modify clinical-grade T cells to target CD19.
Immunol Rev. 2014; 257(1):181-90 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
The advent of efficient approaches to the genetic modification of T cells has provided investigators with clinically appealing methods to improve the potency of tumor-specific clinical grade T cells. For example, gene therapy has been successfully used to enforce expression of chimeric antigen receptors (CARs) that provide T cells with ability to directly recognize tumor-associated antigens without the need for presentation by human leukocyte antigen. Gene transfer of CARs can be undertaken using viral-based and non-viral approaches. We have advanced DNA vectors derived from the Sleeping Beauty (SB) system to avoid the expense and manufacturing difficulty associated with transducing T cells with recombinant viral vectors. After electroporation, the transposon/transposase improves the efficiency of integration of plasmids used to express CAR and other transgenes in T cells. The SB system combined with artificial antigen-presenting cells (aAPC) can selectively propagate and thus retrieve CAR(+) T cells suitable for human application. This review describes the translation of the SB system and aAPC for use in clinical trials and highlights how a nimble and cost-effective approach to developing genetically modified T cells can be used to implement clinical trials infusing next-generation T cells with improved therapeutic potential.

Dotti G, Gottschalk S, Savoldo B, Brenner MK
Design and development of therapies using chimeric antigen receptor-expressing T cells.
Immunol Rev. 2014; 257(1):107-26 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Investigators developed chimeric antigen receptors (CARs) for expression on T cells more than 25 years ago. When the CAR is derived from an antibody, the resultant cell should combine the desirable targeting features of an antibody (e.g. lack of requirement for major histocompatibility complex recognition, ability to recognize non-protein antigens) with the persistence, trafficking, and effector functions of a T cell. This article describes how the past two decades have seen a crescendo of research which has now begun to translate these potential benefits into effective treatments for patients with cancer. We describe the basic design of CARs, describe how antigenic targets are selected, and the initial clinical experience with CAR-T cells. Our review then describes our own and other investigators' work aimed at improving the function of CARs and reviews the clinical studies in hematological and solid malignancies that are beginning to exploit these approaches. Finally, we show the value of adding additional engineering features to CAR-T cells, irrespective of their target, to render them better suited to function in the tumor environment, and discuss how the safety of these heavily modified cells may be maintained.

Davila ML, Bouhassira DC, Park JH, et al.
Chimeric antigen receptors for the adoptive T cell therapy of hematologic malignancies.
Int J Hematol. 2014; 99(4):361-71 [PubMed] Related Publications
The genetic modification of autologous T cells with chimeric antigen receptors (CARs) represents a breakthrough for gene engineering as a cancer therapy for hematologic malignancies. By targeting the CD19 antigen, we have demonstrated robust and rapid anti-leukemia activity in patients with heavily pre-treated and chemotherapy-refractory B cell acute lymphoblastic leukemia (B-ALL). We demonstrated rapid induction of deep molecular remissions in adults, which has been recently confirmed in a case report involving a child with B-ALL. In contrast to the results when treating B-ALL, outcomes have been more modest in patients with chronic lymphocytic leukemia (CLL) or other non-hodgkin's lymphoma (NHL). We review the clinical trial experience targeting B-ALL and CLL and speculate on the possible reasons for the different outcomes and propose potential optimization to CAR T cell therapy when targeting CLL or other indolent NHL. Lastly, we discuss the pre-clinical development and potential for clinical translation for using CAR T cells against multiple myeloma and acute myeloid leukemia. We highlight the potential risks and benefits by targeting these poor outcome hematologic malignancies.

Anurathapan U, Chan RC, Hindi HF, et al.
Kinetics of tumor destruction by chimeric antigen receptor-modified T cells.
Mol Ther. 2014; 22(3):623-33 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
The use of chimeric antigen receptor (CAR)-modified T cells as a therapy for hematologic malignancies and solid tumors is becoming more widespread. However, the infusion of a T-cell product targeting a single tumor-associated antigen may lead to target antigen modulation under this selective pressure, with subsequent tumor immune escape. With the purpose of preventing this phenomenon, we have studied the impact of simultaneously targeting two distinct antigens present on tumor cells: namely mucin 1 and prostate stem cell antigen, both of which are expressed in a variety of solid tumors, including pancreatic and prostate cancer. When used individually, CAR T cells directed against either tumor antigen were able to kill target-expressing cancer cells, but tumor heterogeneity led to immune escape. As a combination therapy, we demonstrate superior antitumor effects using both CARs simultaneously, but this was nevertheless insufficient to achieve a complete response. To understand the mechanism of escape, we studied the kinetics of T-cell killing and found that the magnitude of tumor destruction depended not only on the presence of target antigens but also on the intensity of expression-a feature that could be altered by administering epigenetic modulators that upregulated target expression and enhanced CAR T-cell potency.

Ma Q, Gomes EM, Lo AS, Junghans RP
Advanced generation anti-prostate specific membrane antigen designer T cells for prostate cancer immunotherapy.
Prostate. 2014; 74(3):286-96 [PubMed] Related Publications
BACKGROUND: Adoptive immunotherapy by infusion of designer T cells (dTc) engineered with chimeric antigen receptors (CARs) for tumoricidal activity represents a potentially highly specific modality for the treatment of cancer. In this study, 2nd generation (gen) anti-prostate specific membrane antigen (PSMA) dTc were developed for improving the efficacy of previously developed 1st gen dTc for prostate cancer immunotherapy. The 1st gen dTc are modified with chimeric immunoglobulin-T cell receptor (IgTCR) while the 2nd gen dTc are engineered with an immunoglobulin-CD28-T cell receptor (IgCD28TCR), which incorporates a CD28 costimulatory signal for optimal T cell activation.
METHODS: A 2nd gen anti-PSMA IgCD28TCR CAR was constructed by inserting the CD28 signal domain into the 1st gen CAR. 1st and 2nd gen anti-PSMA dTc were created by transducing human T cells with anti-PSMA CARs and their antitumor efficacy was compared for specific activation on PSMA-expressing tumor contact, cytotoxicity against PSMA-expressing tumor cells in vitro, and suppression of tumor growth in an animal model.
RESULTS: The 2nd gen dTc can be optimally activated to secrete larger amounts of cytokines such as IL2 and IFNγ than 1st gen and to proliferate more vigorously on PSMA-expressing tumor contact. More importantly, the 2nd gen dTc preserve the PSMA-specific cytotoxicity in vitro and suppress tumor growth in animal models with significant higher potency.
CONCLUSIONS: Our results demonstrate that 2nd gen anti-PSMA designer T cells exhibit superior antitumor functions versus 1st gen, providing a rationale for advancing this improved agent toward clinical application in prostate cancer immunotherapy.

Bridgeman JS, Ladell K, Sheard VE, et al.
CD3ζ-based chimeric antigen receptors mediate T cell activation via cis- and trans-signalling mechanisms: implications for optimization of receptor structure for adoptive cell therapy.
Clin Exp Immunol. 2014; 175(2):258-67 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Chimeric antigen receptors (CARs) can mediate redirected lysis of tumour cells in a major histocompatibility complex (MHC)-independent manner, thereby enabling autologous adoptive T cell therapy for a variety of malignant neoplasms. Currently, most CARs incorporate the T cell receptor (TCR) CD3ζ signalling chain; however, the precise mechanisms responsible for CAR-mediated T cell activation are unclear. In this study, we used a series of immunoreceptor tyrosine-based activation motif (ITAM)-mutant and transmembrane-modified receptors to demonstrate that CARs activate T cells both directly via the antigen-ligated signalling chain and indirectly via associated chains within the TCR complex. These observations allowed us to generate new receptors capable of eliciting polyfunctional responses in primary human T cells. This work increases our understanding of CAR function and identifies new avenues for the optimization of CAR-based therapeutic interventions.

Savoldo B, Dotti G
Chimeric antigen receptors (CARs) from bench-to-bedside.
Immunol Lett. 2013 Sep-Oct; 155(1-2):40-2 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Chimeric antigen receptors (CARs) combine the antigen specificity of an antibody with the biologic properties of T lymphocytes. While the concept has been developed more than 20 years ago, only in recent years the clinical application of this approach has produced remarkable objective clinical responses. In this brief review, we outline some specific aspects that have led to antitumor responses in cancer patients.

De Oliveira SN, Ryan C, Giannoni F, et al.
Modification of hematopoietic stem/progenitor cells with CD19-specific chimeric antigen receptors as a novel approach for cancer immunotherapy.
Hum Gene Ther. 2013; 24(10):824-39 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Chimeric antigen receptors (CARs) against CD19 have been shown to direct T-cells to specifically target B-lineage malignant cells in animal models and clinical trials, with efficient tumor cell lysis. However, in some cases, there has been insufficient persistence of effector cells, limiting clinical efficacy. We propose gene transfer to hematopoietic stem/progenitor cells (HSPC) as a novel approach to deliver the CD19-specific CAR, with potential for ensuring persistent production of effector cells of multiple lineages targeting B-lineage malignant cells. Assessments were performed using in vitro myeloid or natural killer (NK) cell differentiation of human HSPCs transduced with lentiviral vectors carrying first and second generations of CD19-specific CAR. Gene transfer did not impair hematopoietic differentiation and cell proliferation when transduced at 1-2 copies/cell. CAR-bearing myeloid and NK cells specifically lysed CD19-positive cells, with second-generation CAR including CD28 domains being more efficient in NK cells. Our results provide evidence for the feasibility and efficacy of the modification of HSPC with CAR as a strategy for generating multiple lineages of effector cells for immunotherapy against B-lineage malignancies to augment graft-versus-leukemia activity.

Hegde M, Corder A, Chow KK, et al.
Combinational targeting offsets antigen escape and enhances effector functions of adoptively transferred T cells in glioblastoma.
Mol Ther. 2013; 21(11):2087-101 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Preclinical and early clinical studies have demonstrated that chimeric antigen receptor (CAR)-redirected T cells are highly promising in cancer therapy. We observed that targeting HER2 in a glioblastoma (GBM) cell line results in the emergence of HER2-null tumor cells that maintain the expression of nontargeted tumor-associated antigens. Combinational targeting of these tumor-associated antigens could therefore offset this escape mechanism. We studied the single-cell coexpression patterns of HER2, IL-13Rα2, and EphA2 in primary GBM samples using multicolor flow cytometry and immunofluorescence, and applied a binomial routine to the permutations of antigen expression and the related odds of complete tumor elimination. This mathematical model demonstrated that cotargeting HER2 and IL-13Rα2 could maximally expand the therapeutic reach of the T cell product in all primary tumors studied. Targeting a third antigen did not predict an added advantage in the tumor cohort studied. We therefore generated bispecific T cell products from healthy donors and from GBM patients by pooling T cells individually expressing HER2 and IL-13Rα2-specific CARs and by making individual T cells to coexpress both molecules. Both HER2/IL-13Rα2-bispecific T cell products offset antigen escape, producing enhanced effector activity in vitro immunoassays (against autologous glioma cells in the case of GBM patient products) and in an orthotopic xenogeneic murine model. Further, T cells coexpressing HER2 and IL-13Rα2-CARs exhibited accentuated yet antigen-dependent downstream signaling and a particularly enhanced antitumor activity.

Katz BZ, Herishanu Y
Therapeutic targeting of CD19 in hematological malignancies: past, present, future and beyond.
Leuk Lymphoma. 2014; 55(5):999-1006 [PubMed] Related Publications
Abstract During the past few decades, CD19 has been at the center of various scientific/translational endeavors to develop targeted therapeutics against B-cell malignancies. Due to the expression pattern of CD19 throughout the B-cell lineage, and on most B-cell malignancies, it became a preferred target for the development of experimental therapeutic agents during the first years of the monoclonal antibodies era. Successful preclinical experiments led to the first generation of clinical trials, based predominantly on toxin/anti-CD19 murine immunoconjugates. These, however, mostly failed due to poor biochemical design of the reagents, and the generation of human anti-murine antibodies. Modern anti-CD19 reagents are based on humanized anti-CD19 antibodies designed to attract components of the immune system, predominantly T-cells, to eliminate CD19+ target cells. These include, for example, modified anti-CD19 antibodies, and bispecific anti-CD19/CD3 antibodies. One of the most attractive approaches to target malignant B-cells is based on the introduction of chimeric antigen receptors (CARs) into patient derived T-cells. CARs are composed of extracellular recognition sequences derived from anti-CD19 antibodies, and intracellular signaling components that can foster T-cell activation. The novel anti-B-cell therapeutics have shown promising clinical effects against various B-cell malignancies, including acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL), although expected side effects (e.g. significant immunosuppression) were also recorded. These novel successful anti-CD19 agents may have the potential to be used in other fields, such as autoimmunity.

Barrett DM, Liu X, Jiang S, et al.
Regimen-specific effects of RNA-modified chimeric antigen receptor T cells in mice with advanced leukemia.
Hum Gene Ther. 2013; 24(8):717-27 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Cytotoxic T lymphocytes modified with chimeric antigen receptors (CARs) for adoptive immunotherapy of hematologic malignancies have demonstrated activity in early phase clinical trials. While T cells bearing stably expressed CARs are efficacious and have potential long-term persistence, temporary expression of a CAR via RNA electroporation is also potentially efficacious in preclinical models. Temporary CAR expression using RNA presents a method of testing CARs clinically with additional safety where there may be concerns about possible chronic "on-target, off-tumor" toxic effects, as the degradation of RNA ensures complete removal of the CAR over time without relying on suicide induction systems. CD19-directed RNA CAR T cells were tested in vivo for efficacy and comparison to lentiviral vector (LV)-generated stable CAR T cells. We tested the hypothesis that multiple infusions of RNA CAR T cells preceded by lymphodepleting chemotherapy could mediate improved survival and sustained antitumor responses in a robust leukemia xenograft model. The saturation strategy using rationally designed multiple infusions of RNA CARs based on multiple model iterations approached the efficacy of a stable LV expression method. Two-color imaging revealed that relapse was a locoregional phenomenon in both the temporary and the stable expression models. In marked contrast to stably expressed CARs with retroviral or LV technology, the efficacy of RNA CARs appears independent of the costimulatory signaling endodomains likely because they more influence proliferation and persistence rather than short-term efficacy. The efficacy of the RNA CAR infusions may approach that of stably expressed CARs, offer theoretically safer initial clinical testing in addition to suicide systems, and allow for rapid and effective iterative preclinical modeling for the testing of new targets.

Azab BM, Dash R, Das SK, et al.
Enhanced prostate cancer gene transfer and therapy using a novel serotype chimera cancer terminator virus (Ad.5/3-CTV).
J Cell Physiol. 2014; 229(1):34-43 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Few options are available for treating patients with advanced prostate cancer (PC). As PC is a slow growing disease and accessible by ultrasound, gene therapy could provide a viable option for this neoplasm. Conditionally replication-competent adenoviruses (CRCAs) represent potentially useful reagents for treating PC. We previously constructed a CRCA, cancer terminator virus (CTV), which showed efficacy both in vitro and in vivo for PC. The CTV was generated on a serotype 5-background (Ad.5-CTV) with infectivity depending on Coxsackie-Adenovirus Receptors (CARs). CARs are frequently reduced in many tumor types, including PCs thereby limiting effective Ad-mediated therapy. Using serotype chimerism, a novel CTV (Ad.5/3-CTV) was created by replacing the Ad.5 fiber knob with the Ad.3 fiber knob thereby facilitating infection in a CAR-independent manner. We evaluated Ad.5/3-CTV in comparison with Ad.5-CTV in low CAR human PC cells, demonstrating higher efficiency in inhibiting cell viability in vitro. Moreover, Ad.5/3-CTV potently suppressed in vivo tumor growth in a nude mouse xenograft model and in a spontaneously induced PC that develops in Hi-myc transgenic mice. Considering the significant responses in a Phase I clinical trial of a non-replicating Ad.5-mda-7 in advanced cancers, Ad.5/3-CTV may exert improved therapeutic benefit in a clinical setting.

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