Chimeric antigen receptor
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Chimeric antigen receptors (CARs, also known as chimeric immunoreceptors, chimeric T cell receptors or artificial T cell receptors) are engineered receptors that combine a new specificity with an immune cell to target cancer cells. Typically, these receptors graft the specificity of a monoclonal antibody onto a T cell. The receptors are called chimeric because they are fused of parts from different sources. CAR-T cell therapy refers to a treatment that uses such transformed cells for cancer therapy.
The basic principle of CAR-T cell design involves recombinant receptors that combine antigen-binding and T-cell activating functions. The general premise of CAR-T cells is to artificially generate T-cells targeted to markers found on cancer cells. Scientists can remove T-cells from a person, genetically alter them, and put them back into the patient for them to attack the cancer cells. Once the T cell has been engineered to become a CAR-T cell, it acts as a "living drug". CAR-T cells create a link between an extracellular ligand recognition domain to an intracellular signalling molecule which in turn activates T cells. The extracellular ligand recognition domain is usually a single-chain variable fragment (scFv). An important aspect of the safety of CAR-T cell therapy is how to ensure that only cancerous tumor cells are targeted, and not normal cells. The specificity of CAR-T cells is determined by the choice of molecule that is targeted.
CAR-Ts can be derived from either a patient's own blood (autologous) or derived from another healthy donor (allogenic). These T-cells are genetically engineered to express an artificial T cell receptor, through which they are targeted to disease-related antigens. This process is MHC independent and thus the targeting efficiency is greatly increased. These CAR-T cells are programmed to target antigens that are present on the surface of tumors. When they come in contact with the antigens on the tumors, the CAR-T cells are activated via the signal peptide, proliferate and become cytotoxic. The CAR-T cells destroy the cancer cells through mechanisms such as extensive stimulated cell proliferation, increasing the degree to which the cell is toxic to other living cells i.e. cytotoxicity, and by causing the increased production of factors that are secreted from cells in the immune system that have an effect on other cells in the organism. These factors are called cytokines and include interleukins, interferons and growth factors.
CAR-T cells are developed to be specific to an antigen expressed on a tumor that is not expressed on healthy cells. CD19 is expressed on B-cells throughout their development and as a result, CD19 is also expressed on nearly all B-cell malignancies. Additionally, CD19 is only expressed in the B-cell lineage and not in any other lineages or tissues. These malignancies include forms of cancer such as acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), and many different forms of Hodgkin’s lymphoma.
Use in cancer
This section needs to be updated.(October 2016)
Adoptive transfer of T cells expressing chimeric antigen receptors is a promising anti-cancer therapeutic as CAR-modified T cells can be engineered to target virtually any tumor associated antigen. There is great potential for this approach to improve patient-specific cancer therapy in a profound way. Following collection of a patient's T cells, the cells are genetically engineered to express CARs specifically directed toward antigens on the patient's tumor cells, then infused back into the patient.
The first step in the introduction of CAR-T cells into the body of a patient is the removal of activated leukocytes from the blood in a process known as leukocyte apheresis. The leukocytes are removed using a blood cell separator. The patient’s autologous peripheral blood mononuclear cells (PBMC) are then separated and collected from the buffy coat that forms. The products of leukocyte apheresis are then transferred into a cell processing center. In the cell processing centre, specific T-cells are activated in a certain environment in which they can actively proliferate. The cells are activated using a type of cytokine called an interleukin, specifically Inter-Leukin 2 (IL-2) as well as anti-CD3 antibodies.
The T-cells are then transfected with CD19 CAR genes by either an integrating gammaretrovirus (RV) or by lentivirus (LV) vectors. These vectors are very safe in modern times due to a partial deletion of the U3 region. The patient undergoes lymphodepletion chemotherapy prior to the introduction of the engineered CD CAR-T cells. The depletion of the number of circulating leukocytes in the patient upregulates the number of cytokines that are produced which help to promote the expansion of the engineered CAR-T cell.
CAR-T cells are undoubtedly a major breakthrough in cancer treatment. However, there are still expected toxicities as well as some unexpected toxicities that come in conjunction to CAR-T cells being introduced into the body. These toxicities include cytokine release syndrome (CRS), neurological toxicity, On-target/Off-Tumour Recognition, insertional mutagenesis and anaphylaxis.
CRS is a condition in which the immune system is activated and releases an increased number of inflammatory cytokines. The clinical manifestations of this syndrome include: high fever, fatigue, myalgia, nausea, tachycardia, capillary leakages, cardiac dysfunction, hepatic failure and renal impairment.
The neurological toxicity associated with CAR-T cells have clinical manifestations that include delirium, the partial loss of the ability to speak a coherent language while still having the ability to interpret language (expressive aphasia), obtundation and seizures. During some clinical trials deaths caused by neurotoxicity have occurred. The main cause of death from neurotoxicity is cerebral edema. In a study carried out by Juno Therapeutics, Inc., five patients enrolled in the trial died as a result of cerebral edema. Two of the patients were treated with cyclophosphamide alone and the remaining three were treated with a combination of cyclophosphamide and fludarabine. In another clinical trial sponsored by the Fred Hutchinson Cancer Research Center, there was one reported case of irreversible and fatal neurological toxicity 122 days after the administration of CAR-T cells.
On-target/Off-tumor recognition occurs when the CAR-T cell recognises the correct antigen, but the antigen is expressed on a non-pathogenic tissue. This adverse effect can vary in severity from B-Cell Aplasia to severe toxicity which leads to death.
Anaphylaxis is an expected side effect as the CAR is made with a foreign monoclonal antibody and as a result, invokes an immune response. There is also a potential for insertional mutagenesis that can occur when inserting vector DNA into a host cell. Lentiviral (LV) vectors carry a lower risk than retroviral (RV) vectors. however, both have the potential to be oncogenic.
There hasn’t been much long-term research done into the effects of CAR-T cells as they are a relatively new medicine still in the trial phases so there is still concern for long-term survival as well as pregnancy complications in female patients treated with CAR-T cells.
Early FDA approvals
The first two FDA approved CAR-T therapies were targeted at CD19 (found on many types of lymphoma cells; mainly B-cell lymphomas). They are approved for relapsed/refractory diffuse large B-cell lymphoma (DLBCL) for axicabtagene ciloleucel and relapsed/refractory B-cell precursor acute lymphoblastic leukemia (ALL) for tisagenlecleucel.
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The ectodomain is the region of the receptor that is exposed to the extracellular fluid and consists of 3 components: a signalling peptide, an antigen recognition region and a spacer.
A signal peptide directs the nascent protein into the endoplasmic reticulum. The signal protein in CAR is called a single-chain variable fragment (scFv), a type of protein known as a fusion protein or chimeric protein. A fusion protein is a protein that is formed by merging two or more genes that code originally for different proteins but when they are translated in the cell, the translation produces one or more polypeptides with functional properties derived for each of the original genes.
A scFv is a chimeric protein made up of the light and heavy chains of immunoglobins connected with a short linker peptide. The linker consists of hydrophilic residues with stretches of glycine and serine in it for flexibility as well as stretches of glutamate and lysine for added solubility.
The transmembrane domain is a hydrophobic alpha helix that spans the membrane. The transmembrane domain is essential for the stability of the receptor as a whole. At present, the CD28 transmembrane domain is the most stable of the domains.
Generally, the transmembrane domain from the most membrane proximal component of the endodomain is used. Interestingly, using the CD3-zeta transmembrane domain may result in incorporation of the artificial TCR into the native TCR, a factor that is dependent on the presence of the native CD3-zeta transmembrane charged aspartic acid residue. Different transmembrane domains result in different receptor stability. The CD28 transmembrane domain results in a highly expressed, stable receptor.
This is the functional end of the receptor. After antigen recognition, receptors cluster and a signal is transmitted to the cell. The most commonly used endodomain component is CD3-zeta which contains 3 ITAMs. This transmits an activation signal to the T cell after the antigen is bound. CD3-zeta may not provide a fully competent activation signal and co-stimulatory signaling is needed. For example, chimeric CD28 and OX40 can be used with CD3-Zeta to transmit a proliferative/survival signal or all three can be used together.
First generation CARs were developed in 1989 by Gideon Gross and Zelig Eshhar at Weizmann Institute, Israel. The first generation of CARs are composed of an extracellular binding domain, a hinge region, a transmembrane domain, and one or more intracellular signaling domains. Extracellular binding domain contains single‐chain variable fragments (scFvs) derived from tumor antigen‐reactive antibodies and usually have high specificity to tumor antigen. All CARs harbor the CD3ζ chain domain as the intracellular signaling domain, which is the primary transmitter of signals. Second generation CARs also contain co‐stimulatory domains, like CD28 and/or 4‐1BB. The involvement of these intracellular signaling domains improve T cell proliferation, cytokine secretion, resistance to apoptosis, and in vivo persistence. Besides co-stimulatory domains, the third‐generation CARs combine multiple signaling domains, such as CD3z-CD28-41BB or CD3z-CD28-OX40, to augment T cell activity. Preclinical data shows the third-generation CARs exhibit improved effector functions and in vivo persistence as compared to second‐generation CARs. Recently, the fourth‐generation CARs (also known as TRUCKs or armored CARs), combine the expression of a second‐generation CAR with factors that enhance anti‐tumoral activity (e.g., cytokines, co‐stimulatory ligands).
The evolution of CAR therapy is an excellent example of the application of basic research to the clinic. The PI3K binding site used was identified in co-receptor CD28, while the ITAM motifs were identified as a target of the CD4- and CD8-p56lck complexes.
The introduction of Strep-tag II sequence (an eight-residue minimal peptide sequence (Trp-Ser-His-Pro-Gln-Phe-Glu-Lys) that exhibits intrinsic affinity toward streptavidin) into specific sites in synthetic CARs or natural T-cell receptors provides engineered T cells with an identification marker for rapid purification, a method for tailoring spacer length of chimeric receptors for optimal function and a functional element for selective antibody-coated, microbead-driven, large-scale expansion. Strep-tag can be used to stimulate the engineered cells, causing them to grow rapidly. Using an antibody that binds the Strep-tag, the engineered cells can be expanded by 200-fold. Unlike existing methods this technology stimulates only cancer-specific T cells.
Smart T cell
Combined with exogenous molecules, some synthetic control devices have been implemented on CAR-T cells and alter the cell activity. Smart T cell is engineered with suicide gene or other synthetic control panels to precisely control therapeutic function over the timing and dosage, there by alleviating cytotoxicity. Several strategies to improve safety and efficacy of CAR-T cells are:
Suicide gene engineering: engineered T cells are incorporated with suicide genes, which can be activated by extracellular molecule and then induce T cell apoptosis. Herpes simplex virus thymidine kinase (HSV-TK) and inducible caspase 9 (iCas9) are two types suicide genes have been integrated into CAR-T cells. In iCas9 system, the suicide gene is composed of the sequence of the mutated FK506-binding protein with high specificity to a small-molecule, AP1903 and a gene encoding human caspase 9 switch. When the release of cytokines by CAR-T cells becomes more pronounced than basic levels, the iCas9 can be dimerized and lead to rapid apoptosis of T cells. Although both suicide genes demonstrate a noticeable function of as a safety switch in clinical trials for cellular therapies, some hinder defects limit the application of this strategy. HSV-TK is derived from virus and may be immunogenic to humans. The suicide gene strategies may not act quickly enough to eliminate off-tumor cytotoxicity as well.
Dual-antigen receptor: T cells are engineered to express two tumor-associated antigen receptors at the same time. The dual-antigen receptor of engineered T cell module has been reported to have less intense side effects. The activation of CAR-T cell via TCR-CD3ζ signal transduction pathway is transient and a complementary signal pathway provided by co-stimulatory molecules on antigen presenting cells promotes survival of modified-T cell can ability in controlling tumor. An in vivo study in mice shows the dual-receptor T cells effectively eradicated prostate cancer and achieved complete long-term survival.
ON-switch: ON-switch CAR-T cell split synthetic receptors into two parts: the first part mainly contains an antigen binding domain towards and the other part features two different downstream signaling elements (e.g. CD3ζ and 4-1BB). Upon the presence of an exogenous molecule (rapamycin analogs for example), two physically separated signaling elements fuse together and CAR-T cells exert therapeutic functions. In this mechanism, the engineered T cell shows therapeutic function only in the presence of both tumor antigen and a benign exogenous molecule.
Bifunctional molecules as switches: The bispecific antibodies are developed as an efficacious bridge to target cytotoxic T cells to cancer cells and causes localized T cell activation. In this strategy, the bispecific antibody targets CD3 molecule of T cell and tumor-associated antigen presented on cancer cell surface. The anti-CD20/CD3 bispecific molecule shows high specificity to both malignant B cells and cancer cells in mice. FITC is another bifunctional molecule used in this strategy. FITC can redirect and regulate the activity of the FITC-specific CAR-T cells toward tumor cells with folate receptors.
SMDC adaptor technology
SMDCs (small molecule drug conjugates) platform in immuno-oncology is a novel (currently experimental) approach that makes possible the engineering of a single universal CAR T cell, which binds with extraordinarily high affinity to a benign molecule designated as FITC. These cells are then used to treat various cancer types when co-administered with bispecific SMDC adaptor molecules. These unique bispecific adaptors are constructed with a FITC molecule and a tumor-homing molecule to precisely bridge the universal CAR T cell with the cancer cells, which causes localized T cell activation. Anti-tumor activity in mice is induced only when both the universal CAR T cells plus the correct antigen-specific adaptor molecules are present. Anti-tumor activity and toxicity can be controlled by adjusting the administered adaptor molecule dosing. Treatment of antigenically heterogeneous tumors can be achieved by administration of a mixture of the desired antigen-specific adaptors. Thus, several challenges of current CAR T cell therapies, such as:
- the inability to control the rate of cytokine release and tumor lysis
- the absence of an “off switch” that can terminate cytotoxic activity when tumor eradication is complete
- a requirement to generate a different CAR T cell for each unique tumor antigen
The First CAR-T therapy has been approved by FDA is Novartis's tisagenlecleucel, also known as Kymriah. The first launch of Kymriah is in August, 2016. The clinical trial result shows an 83% remission rate of all types of B-cell acute lymphoblastic leukemia after three months post treatment. However, 49% of patients also suffered severe side-effects, such as neurotoxicity and cytokine release syndrome. These side effects have been reported to be responsible for multiple death in late-stage clinical trials with CAR-T therapy. As of August 2017 there were around 200 clinical trials happening globally involving CAR-T cells. Of those trials, around 65% were trials in which haematological malignancies were explored, and 80% of them involved CD19 CAR-T cells targeting the B-cell cancers. Studies had begun by 2016 to explore the viability of other antigens such as CD20.
Armoured CAR-T cells
CAR-T cells are more effective on liquid tumours and have not shown much promise in treating solid tumours. Ovarian cancer is one of the major killers of women since most cases of ovarian cancer (approximately 70%) are diagnosed at a late stage. Of those diagnosed, approximately 30% are expected to survive for five years. Ovarian cancer is difficult to treat because it is a solid tumour with a microenvironment that suppresses adoptively transferred T-Cells. The hostile microenvironment of the solid tumour is also composed of myeloid-derived suppressor cells (MDSC) and tumour-associated macrophages (TAMs). TAMs and MDSCs promote aspects of tumour growth and development. The tumour microenvironment is also composed of vascular leukocytes (VLC) which promote the progression of the solid tumour. All of these components of the microenvironment of the tumour act to suppress T-Cells.
The armoured CAR-T cell is engineered to secrete potent cytokines such as interleukin 12 (I L-12) as well as expressing tethered or soluble ligands on its membrane to improve the efficacy of the CAR-T cell. The secretion of IL-12 is promising as it is a proinflammatory cytokine known for its ability to improve the cytotoxic capabilities of CD8+ cells, engage and recruit macrophages to prevent the escape of antigen-loss tumour cells. CD19 CAR-T cells secreting IL-12 could eradicate established lymphoma in mice without the need for pre-conditioning through the induction of host immunity. A recent phase II clinical trial was carried out in ovarian cancer patients where they were administered IL-12. This treatment led to stable disease in 50% of the cohort.
- Fox, Maggie (July 12, 2017). "New Gene Therapy for Cancer Offers Hope to Those With No Options Left". NBC News.
- Sadelain M, Brentjens R, Rivière I (April 2013). "The basic principles of chimeric antigen receptor design". Cancer Discovery. 3 (4): 388–98. doi:10.1158/2159-8290.CD-12-0548. PMC . PMID 23550147.
- Srivastava S, Riddell SR (August 2015). "Engineering CAR-T cells: Design concepts". Trends in Immunology. 36 (8): 494–502. doi:10.1016/j.it.2015.06.004. PMC . PMID 26169254.
- Hartmann J, Schüßler-Lenz M, Bondanza A, Buchholz CJ (2017). "Clinical development of CAR T cells-challenges and opportunities in translating innovative treatment concepts". EMBO Molecular Medicine. 9 (9): 1183–1197. doi:10.15252/emmm.201607485.
- Hartmann J, Schüßler-Lenz M, Bondanza A, Buchholz CJ (September 2017). "Clinical development of CAR T cells-challenges and opportunities in translating innovative treatment concepts". EMBO Molecular Medicine. 9 (9): 1183–1197. doi:10.15252/emmm.201607485. PMC . PMID 28765140.
- Tang XJ, Sun XY, Huang KM, Zhang L, Yang ZS, Zou DD, Wang B, Warnock GL, Dai LJ, Luo J (December 2015). "Therapeutic potential of CAR-T cell-derived exosomes: a cell-free modality for targeted cancer therapy". Oncotarget. 6 (42): 44179–90. doi:10.18632/oncotarget.6175. PMC . PMID 26496034.
- Maude SL, Teachey DT, Porter DL, Grupp SA (June 2015). "CD19-targeted chimeric antigen receptor T-cell therapy for acute lymphoblastic leukemia". Blood. 125 (26): 4017–23. doi:10.1182/blood-2014-12-580068. PMC . PMID 25999455.
- Jacobson CA, Ritz J (November 2011). "Time to put the CAR-T before the horse". Blood. 118 (18): 4761–2. doi:10.1182/blood-2011-09-376137. PMID 22053170.
- Jin C, Yu D, Hillerdal V, Wallgren A, Karlsson-Parra A, Essand M (2014-03-05). "Allogeneic lymphocyte-licensed DCs expand T cells with improved antitumor activity and resistance to oxidative stress and immunosuppressive factors". Molecular Therapy. Methods & Clinical Development. 1: 14001. doi:10.1038/mtm.2014.1. PMC . PMID 26015949.
- Makita S, Yoshimura K, Tobinai K (June 2017). "Clinical development of anti-CD19 chimeric antigen receptor T-cell therapy for B-cell non-Hodgkin lymphoma". Cancer Science. 108 (6): 1109–1118. doi:10.1111/cas.13239. PMID 28301076.
- Jin C, Fotaki G, Ramachandran M, Nilsson B, Essand M, Yu D (July 2016). "Safe engineering of CAR T cells for adoptive cell therapy of cancer using long-term episomal gene transfer". EMBO Molecular Medicine. 8 (7): 702–11. doi:10.15252/emmm.201505869. PMID 27189167.
- Muranski P, Boni A, Wrzesinski C, Citrin DE, Rosenberg SA, Childs R, Restifo NP (December 2006). "Increased intensity lymphodepletion and adoptive immunotherapy--how far can we go?". Nature Clinical Practice Oncology. 3 (12): 668–81. doi:10.1038/ncponc0666. PMC . PMID 17139318.
- Breslin S (February 2007). "Cytokine-release syndrome: overview and nursing implications". Clinical Journal of Oncology Nursing. 11 (1 Suppl): 37–42. doi:10.1188/07.CJON.S1.37-42. PMID 17471824.
- Bonifant CL, Jackson HJ, Brentjens RJ, Curran KJ (2016). "Toxicity and management in CAR-T cell therapy". Molecular Therapy Oncolytics. 3: 16011. doi:10.1038/mto.2016.11. PMC . PMID 27626062.
- "Study Evaluating the Efficacy and Safety of JCAR015 in Adult B-cell Acute Lymphoblastic Leukemia (B-ALL)". ClinicalTrials.gov. Retrieved 2018-02-21.
- Turtle CJ, Hanafi LA, Berger C, Gooley TA, Cherian S, Hudecek M, Sommermeyer D, Melville K, Pender B, Budiarto TM, Robinson E, Steevens NN, Chaney C, Soma L, Chen X, Yeung C, Wood B, Li D, Cao J, Heimfeld S, Jensen MC, Riddell SR, Maloney DG (June 2016). "CD19 CAR-T cells of defined CD4+:CD8+ composition in adult B cell ALL patients". The Journal of Clinical Investigation. 126 (6): 2123–38. doi:10.1172/JCI85309. PMC . PMID 27111235.
- Thumbs Up to Latest CAR-T cell Approval - New era for lymphoma, leukemia, possibly other cancers. Oct 2017
- Zhang C, Liu J, Zhong JF, Zhang X (2017-06-24). "Engineering CAR-T cells". Biomarker Research. 5: 22. doi:10.1186/s40364-017-0102-y. PMID 28652918.
- Monnier PP, Vigouroux RJ, Tassew NG (April 2013). "In Vivo Applications of Single Chain Fv (Variable Domain) (scFv) Fragments". Antibodies. 2 (2): 193–208. doi:10.3390/antib2020193.
- Baldo BA (May 2015). "Chimeric fusion proteins used for therapy: indications, mechanisms, and safety". Drug Safety. 38 (5): 455–79. doi:10.1007/s40264-015-0285-9. PMID 25832756.
- Bridgeman JS, Hawkins RE, Bagley S, Blaylock M, Holland M, Gilham DE (June 2010). "The optimal antigen response of chimeric antigen receptors harboring the CD3zeta transmembrane domain is dependent upon incorporation of the receptor into the endogenous TCR/CD3 complex". Journal of Immunology. 184 (12): 6938–49. doi:10.4049/jimmunol.0901766. PMID 20483753.
- Casucci M, Bondanza A (2011). "Suicide gene therapy to increase the safety of chimeric antigen receptor-redirected T lymphocytes". Journal of Cancer. 2: 378–82. doi:10.7150/jca.2.378. PMC . PMID 21750689.
- Gross G, Gorochov G, Waks T, Eshhar Z (February 1989). "Generation of effector T cells expressing chimeric T cell receptor with antibody type-specificity". Transplantation Proceedings. 21 (1 Pt 1): 127–30. PMID 2784887.
- Rosenbaum L (October 2017). "Tragedy, Perseverance, and Chance - The Story of CAR-T Therapy". The New England Journal of Medicine. 377 (14): 1313–1315. doi:10.1056/NEJMp1711886. PMID 28902570.
- Gross G, Waks T, Eshhar Z (December 1989). "Expression of immunoglobulin-T-cell receptor chimeric molecules as functional receptors with antibody-type specificity". Proceedings of the National Academy of Sciences of the United States of America. 86 (24): 10024–8. Bibcode:1989PNAS...8610024G. doi:10.1073/pnas.86.24.10024. JSTOR 34790. PMC . PMID 2513569.
- Chmielewski M, Abken H (2015). "TRUCKs: the fourth generation of CARs". Expert Opin Biol. 15 (8): 1145–1154. doi:10.1517/14712598.2015.1046430.
- Rudd CE, Schneider H (July 2003). "Unifying concepts in CD28, ICOS and CTLA4 co-receptor signalling". Nature Reviews. Immunology. 3 (7): 544–56. doi:10.1038/nri1131. PMID 12876557.
- Rudd CE (January 1999). "Adaptors and molecular scaffolds in immune cell signaling". Cell. 96 (1): 5–8. doi:10.1016/S0092-8674(00)80953-8. PMID 9989491.
- Schmidt TG, Skerra A (2007). "The Strep-tag system for one-step purification and high-affinity detection or capturing of proteins". Nature Protocols. 2 (6): 1528–35. doi:10.1038/nprot.2007.209. PMID 17571060.
- Liu L, Sommermeyer D, Cabanov A, Kosasih P, Hill T, Riddell SR (April 2016). "Inclusion of Strep-tag II in design of antigen receptors for T-cell immunotherapy". Nature Biotechnology. 34 (4): 430–4. doi:10.1038/nbt.3461. PMC . PMID 26900664.
- Crafting a better T cell for immunotherapy. New technology aims to reduce patients’ waiting time, increase potency of T-cell therapy
- Zhang E, Xu H (2017). "A new insight in chimeric antigen receptor‐engineered T cells for cancer immunotherapy". Hematol Oncol. 10 (1). doi:10.1186/s13045-016-0379-6.
- Bonini C, Ferrari G (1997). "HSV-TK gene transfer into donor lymphocytes for control of allogeneic graft-versus-leukemia". Science. 276: 1719–1724. doi:10.1126/science.276.5319.1719.
- Quintarelli C, Vera JF (2007). "Co-expression of cytokine and suicide genes to enhance the activity and safety of tumor-specific cytotoxic T lymphocytes". Blood. 110: 2793–2802. doi:10.1182/blood-2007-02-072843. PMC .
- Riddell SR, Elliott M (1996). "T-cell mediated rejection of gene-modified HIV-specific cytotoxic T lymphocytes in HIV-infected patients". Nat Med. 2: 216–223. doi:10.1038/nm0296-216.
- Maher J, Brentjens RJ (2002). "TCR". Nat Biotechnol. 20: 70–75. doi:10.1038/nbt0102-70.
- Liu JC, Voisin V (2012). "Seventeen-gene signature from enriched Her2/Neu mammary tumor-initiating cells predicts clinical outcome for human HER2+: ERα−breast cancer". PNAS. 109: 5832–5837. Bibcode:2012PNAS..109.5832L. doi:10.1073/pnas.1201105109. PMC .
- Wilkie S, van Schalkwyk MC (2012). "Dual targeting of ErbB2 and MUC1 in breast cancer using chimeric antigen receptors engineered to provide complementary signaling". Clin Immunol. 32: 1059–1070. doi:10.1007/s10875-012-9689-9.
- Wu CY (2015). "Remote control of therapeutic T cells through a small molecule-gated chimeric receptor". Science. 350: aab4077. Bibcode:2015Sci...350.4077W. doi:10.1126/science.aab4077. PMC .
- Frankel SR (2013). "Targeting T cells to tumor cells using bispecific antibodies". Curr Opin Chem Biol. 17: 385–392. doi:10.1016/j.cbpa.2013.03.029.
- Sun LL (2015). "Anti-CD20/CD3 T cell-dependent bispecific antibody for the treatment of B cell malignancies". Sci Transl Med. 7: 287ra70. doi:10.1126/scitranslmed.aaa4.
- Kim CH (2013). "Bispecific small molecule-antibody conjugate targeting prostate cancer". PNAS. 110: 17796–17801. Bibcode:2013PNAS..11017796K. doi:10.1073/pnas.1316026110.
- Lee, Yong Gu; Chu, Haiyan; Low, Philip S (2017). "Abstract LB-187: New methods for controlling CAR T cell-mediated cytokine storms". Cancer Research. 77 (13 Supplement): LB–187. doi:10.1158/1538-7445.AM2017-LB-187. Lay summary – Medical Xpress (April 21, 2016).
- SMDC TECHNOLOGY.[dead link] ENDOCYTE
- "Endocyte Announces Promising Preclinical Data for Application of SMDC Technology in CAR T Cell Therapy in Late-Breaking Abstract at American Association for Cancer Research (AACR) Annual Meeting 2016" (Press release). Endocyte. April 19, 2016. Retrieved December 20, 2017.
- "A Cure for Cancer? How CAR-T Therapy is Revolutionizing Oncology" (Press release). labiotech. March 8, 2018. Retrieved April 19, 2018.
- Almåsbak H, Aarvak T, Vemuri MC (2016). "CAR T Cell Therapy: A Game Changer in Cancer Treatment". Journal of Immunology Research. 2016: 5474602. doi:10.1155/2016/5474602. PMID 27298832.
- Lipowska-Bhalla G, Gilham DE, Hawkins RE, Rothwell DG (July 2012). "Targeted immunotherapy of cancer with CAR T cells: achievements and challenges". Cancer Immunology, Immunotherapy. 61 (7): 953–62. doi:10.1007/s00262-012-1254-0. PMID 22527245.
- Sadelain M, Brentjens R, Rivière I (April 2009). "The promise and potential pitfalls of chimeric antigen receptors". Current Opinion in Immunology. 21 (2): 215–23. doi:10.1016/j.coi.2009.02.009. PMC . PMID 19327974.
- Quatromoni JG, Eruslanov E (2012-10-10). "Tumor-associated macrophages: function, phenotype, and link to prognosis in human lung cancer". American Journal of Translational Research. 4 (4): 376–89. PMC . PMID 23145206.
- Sinha P, Clements VK, Bunt SK, Albelda SM, Ostrand-Rosenberg S (July 2007). "Cross-talk between myeloid-derived suppressor cells and macrophages subverts tumor immunity toward a type 2 response". Journal of Immunology. 179 (2): 977–83. PMID 17617589.
- Bak SP, Alonso A, Turk MJ, Berwin B (December 2008). "Murine ovarian cancer vascular leukocytes require arginase-1 activity for T cell suppression". Molecular Immunology. 46 (2): 258–68. doi:10.1016/j.molimm.2008.08.266. PMC . PMID 18824264.
- Chmielewski M, Kopecky C, Hombach AA, Abken H (September 2011). "IL-12 release by engineered T cells expressing chimeric antigen receptors can effectively Muster an antigen-independent macrophage response on tumor cells that have shut down tumor antigen expression". Cancer Research. 71 (17): 5697–706. doi:10.1158/0008-5472.CAN-11-0103. PMID 21742772.
- Kueberuwa G, Kalaitsidou M, Cheadle E, Hawkins RE, Gilham DE (March 2018). "CD19 CAR T Cells Expressing IL-12 Eradicate Lymphoma in Fully Lymphoreplete Mice through Induction of Host Immunity". Molecular Therapy Oncolytics. 8: 41–51. doi:10.1016/j.omto.2017.12.003. PMC . PMID 29367945.
- Yeku OO, Purdon TJ, Koneru M, Spriggs D, Brentjens RJ (September 2017). "Armored CAR T cells enhance antitumor efficacy and overcome the tumor microenvironment". Scientific Reports. 7 (1): 10541. Bibcode:2017NatSR...710541Y. doi:10.1038/s41598-017-10940-8. PMID 28874817.