Remote control of therapeutic T cells through a small molecule-gated chimeric receptor

Redox-responsive interleukin-2 nanogel specifically and safely promotes the proliferation and memory precursor differentiation of tumor-reactive T-cells

Interleukin-2 (IL-2) is a potent T-cell mitogen that can adjuvant anti-cancer adoptive T-cell transfer (ACT) immunotherapy by promoting T-cell engraftment. However, the clinical applications of IL-2 in combination with ACT are greatly hindered by the severe adverse effects such as vascular leak syndrome (VLS). Here, we developed a synthetic delivery strategy for IL-2 via backpacking redox-responsive IL-2/Fc nanogels (NGs) to the plasma membrane of adoptively transferred T-cells. The NGs prepared by traceless chemical cross-linking of cytokine proteins selectively released the cargos in response to T-cell receptor activation upon antigen recognition in tumors. We found that IL-2/Fc delivered by T-cell surface-bound NGs expanded transferred tumor-reactive T-cells 80-fold more than the free IL-2/Fc of an equivalent dose administered systemically and showed no effects on tumor-infiltrating regulatory T-cell expansion. Intriguingly, IL-2/Fc NG backpacks that facilitated a sustained and slow release of IL-2/Fc also promoted the CD8+ memory precursor differentiation and induced less T-cell exhaustion in vitro compared to free IL-2/Fc. The controlled responsive delivery of IL-2/Fc enabled the safe administration of repeated doses of the stimulant cytokine with no overt toxicity and improved efficacy against melanoma metastases in a mice model.

Synthetic Biology: Engineering Mammalian Cells To Control Cell-to-Cell Communication at Will

Cell-to-cell communication plays a key role in the regulation of many natural biological processes. Recent advances in mammalian synthetic biology are making it possible to rationally engineer cell-to-cell communication for therapeutic and other purposes. Here, we review state-of-the-art engineering principles to control cell-to-cell communication, focusing on communication between mammalian cells with diffusible factors (e.g., small molecules or exosomes) or direct cell contact, and on interkingdom communication between mammalian cells and bacteria. Potential applications include construction of artificial tissues able to perform complex computations, sophisticated cell-based cancer therapies, use of mammalian cells as a new class of cargo delivery modality, development of design principles to control pattern formation of cell populations, and treatment of infectious diseases. We also discuss the challenges facing practical applications, and possible enabling technologies to overcome them.

Engineered Cell-Based Therapeutics: Synthetic Biology Meets Immunology

Synthetic Biology has enabled new approaches to several medical applications including the development of immunotherapies based on bioengineered cells, and most notably the engineering of T-cells with tumor-targeting receptors, the Chimeric Antigen Receptor (CAR)-T cells. CAR-T-cells have successfully treated blood tumors such as large B-cell lymphoma and promise a new scenario of therapeutic interventions also for solid tumors. Learning the lesson from CAR-T cells, we can foster the reprogramming of T lymphocytes with enhanced survival and functional activity in depressing tumor microenvironment, or to challenge diseases such as infections, autoimmune and chronic inflammatory disorders. This review will focus on the most updated bioengineering approaches to increase control, and safety of T-cell activity and to immunomodulate the extracellular microenvironment to augment immune responses. We will also discuss on applications beyond cancer treatment with implications toward the understanding and cure of a broader range of diseases by means of mammalian cells engineering.

Killing Mechanisms of Chimeric Antigen Receptor (CAR) T Cells

Effective adoptive T cell therapy (ACT) comprises the killing of cancer cells through the therapeutic use of transferred T cells. One of the main ACT approaches is chimeric antigen receptor (CAR) T cell therapy. CAR T cells mediate MHC-unrestricted tumor cell killing by enabling T cells to bind target cell surface antigens through a single-chain variable fragment (scFv) recognition domain. Upon engagement, CAR T cells form a non-classical immune synapse (IS), required for their effector function. These cells then mediate their anti-tumoral effects through the perforin and granzyme axis, the Fas and Fas ligand axis, as well as the release of cytokines to sensitize the tumor stroma. Their persistence in the host and functional outputs are tightly dependent on the receptor's individual components-scFv, spacer domain, and costimulatory domains-and how said component functions converge to augment CAR T cell performance. In this review, we bring forth the successes and limitations of CAR T cell therapy. We delve further into the current understanding of how CAR T cells are designed to function, survive, and ultimately mediate their anti-tumoral effects.

T-cells "à la CAR-T(e)" - Genetically engineering T-cell response against cancer

The last decade will be remembered as the dawn of the immunotherapy era during which we have witnessed the approval by regulatory agencies of genetically engineered CAR T-cells and of checkpoint inhibitors for cancer treatment. Understandably, T-lymphocytes represent the essential player in these approaches. These cells can mediate impressive tumor regression in terminally-ill cancer patients. Moreover, they are amenable to genetic engineering to improve their function and specificity. In the present review, we will give an overview of the most recent developments in the field of T-cell genetic engineering including TCR-gene transfer and CAR T-cells strategies. We will also elaborate on the development of other types of genetic modifications to enhance their anti-tumor immune response such as the use of co-stimulatory chimeric receptors (CCRs) and unconventional CARs built on non-antibody molecules. Finally, we will discuss recent advances in genome editing and synthetic biology applied to T-cell engineering and comment on the next challenges ahead.

A novel luciferase-based assay for the detection of Chimeric Antigen Receptors

Chimeric Antigen Receptor-T (CAR-T) cell immunotherapy has produced dramatic responses in hematologic malignancies. One of the challenges in the field is the lack of a simple assay for the detection of CARs on the surface of immune effector cells. In this study, we describe a novel luciferase-based assay, termed Topanga Assay, for the detection of CAR expression. The assay utilizes a recombinant fusion protein, called Topanga reagent, generated by joining the extra-cellular domain of a CAR-target in frame with one of the marine luciferases or their engineered derivatives. The assay involves incubation of CAR expressing cells with the Topanga reagent, a few washes and measurement of luminescence. The assay can detect CARs comprising either immunoglobulin- or non-immunoglobulin-based antigen binding domains. We further demonstrate that addition of epitope tags to the Topanga reagent not only allows its convenient one step purification but also extends its use for detection of CAR cells using flow cytometry. However, crude supernatant containing the secreted Topanga reagent can be directly used in both luminescence and flow-cytometry based assays without prior protein purification. Our results demonstrate that the Topanga assay is a highly sensitive, specific, convenient, economical and versatile assay for the detection of CARs.

Structural basis for chemically-induced homodimerization of a single domain antibody

Chemically-induced dimerization (CID) systems are essential tools to interrogate and control biological systems. AcVHH is a single domain antibody homo-dimerizing upon caffeine binding. AcVHH has a strong potential for clinical applications through caffeine-mediated in vivo control of therapeutic gene networks. Here we provide the structural basis for caffeine-induced homo-dimerization of acVHH.

CAR T Cells: A Snapshot on the Growing Options to Design a CAR

Adoptive cell therapy of malignant diseases with chimeric antigen receptor (CAR) modified T cells rapidly advanced from pre-clinical models to commercial approvals within 2 decades. CARs redirect patient's T cells towards cancer cells and activate the engineered cells for a cytolytic attack resulting in the destruction of the cognate target cell. CAR T cells have demonstrated their powerful capacities in inducing complete and lasting remissions of leukemia/lymphoma in an increasing number of trials worldwide. Since the early 90's, the design of CARs went through various steps of optimization until the very recent developments which include CARs with logic gating in the recognition of antigen patterns on target cells and TRUCKs with a target recognition induced delivery of immune modulating agents. Here we review the generations in CAR design, the impact of specific modifications, the strategies to improve the safety of CAR T cell therapy, and the challenges to adapt the CAR design for broader applications.

Biologie, concepts et principes des CAR-T cells

CAR-T CELLS

BIOLOGY, CONCEPTS AND PRINCIPLES: The development of new anti-tumor immunotherapy approaches has recently dramatically increased. Progresses made in molecular biology and the development of various genetic manipulation tools allow the "reprogrammation" of T cells in order to make them express a chimeric receptor including the variable part of an immunoglobulin capable of recognizing a tumor antigen along with the expression of molecules involved in T-lymphocyte activation signaling. Genetically modified T-cells, called "CAR (chimeric antigen receptors) -T cells", have yielded impressive clinical results in the treatment of relapsed or refractory lymphoid hematological malignancies after conventional treatments and are in development in solid tumors. Different generations of CAR-T cells have been developed and technological progress makes it possible to envisage modulations of gene constructs that could further optimize the efficacy and tolerance of CAR-T cells. The first challenge of these approaches concerns the identification of specific tumor antigen targets in order to limit the on-target/off-tumor effects and the loss of expression of the target. Approaches i) targeting several antigens or ii) limiting the duration of expression of CAR in lymphocytes or iii) destroying CAR-T cells by a suicide gene. Interesting approaches are the second objective of improvement concerns the accessibility of CAR-T cells to tumor sites and the control of the immune escape mechanisms of tumor cells to the cytotoxicity of CAR-T cells. This issue is currently under the way of search of innovative strategies that should improve the clinical effectiveness of CAR-T cells, especially in solid tumors. Cet article fait partie du numéro supplément Les cellules CAR-T : une révolution thérapeutique ? réalisé avec le soutien institutionnel des partenaires Gilead : Kite et Celgene.

Engineering Precision Medicine

Advances in genomic sequencing and bioinformatics have led to the prospect of precision medicine where therapeutics can be advised by the genetic background of individuals. For example, mapping cancer genomics has revealed numerous genes that affect the therapeutic outcome of a drug. Through materials and cell engineering, many opportunities exist for engineers to contribute to precision medicine, such as engineering biosensors for diagnosis and health status monitoring, developing smart formulations for the controlled release of drugs, programming immune cells for targeted cancer therapy, differentiating pluripotent stem cells into desired lineages, fabricating bioscaffolds that support cell growth, or constructing "organs-on-chips" that can screen the effects of drugs. Collective engineering efforts will help transform precision medicine into a more personalized and effective healthcare approach. As continuous progress is made in engineering techniques, more tools will be available to fully realize precision medicine's potential.

Teaching an old dog new tricks: next-generation CAR T cells

Adoptive T cell therapy (ACT) refers to the therapeutic use of T cells. T cells genetically engineered to express chimeric antigen receptors (CAR) constitute the most clinically advanced form of ACT approved to date for the treatment of CD19-positive leukaemias and lymphomas. CARs are synthetic receptors that are able to confer antigen-binding and activating functions on T cells with the aim of therapeutically targeting cancer cells. Several factors are essential for CAR T cell therapy to be effective, such as recruitment, activation, expansion and persistence of bioengineered T cells at the tumour site. Despite the advances made in CAR T cell therapy, however, most tumour entities still escape immune detection and elimination. A number of strategies counteracting these problems will need to be addressed in order to render T cell therapy effective in more situations than currently possible. Non-haematological tumours are also the subject of active investigation, but ACT has so far shown only marginal success rates in these cases. New approaches are needed to enhance the ability of ACT to target solid tumours without increasing toxicity, by improving recognition, infiltration, and persistence within tumours, as well as an enhanced resistance to the suppressive tumour microenvironment.

Engineering and Design of Chimeric Antigen Receptors

T cells engineered with chimeric antigen receptors (CARs) have emerged as a potent new class of therapeutics for cancer, based on their remarkable potency in blood cancers. Since the first clinical reports of their efficacy emerged 7 years ago, investigators have focused on the mechanisms and properties that make CARs effective or toxic, and their effects on T cell biology. Novel CAR designs coupled with improvements in gene transfer technology, incorporating advances in gene editing, have the potential to increase access to engineered cell therapies, as well as improve their potency in solid tumors.

Critical factors in chimeric antigen receptor-modified T-cell (CAR-T) therapy for solid tumors

The success of chimeric antigen receptor-modified T-cell (CAR-T) therapy for B-cell lymphocyte malignancies targeting CD19 places it in a rapidly growing field in cancer immunotherapy for both hematological and solid tumors. However, the two types of tumor are quite different in the following respects. Solid tumors are characterized by complex vasculatures and matrix barriers that significantly affect T-cell functions and migration. Moreover, various immunosuppressive molecules expressed in the tumor microenvironment can impede T-cell activation, and the high metabolic rate of tumors competitively suppresses the metabolism of immune cells. All these factors will exert their influences on the development of a cancer, which is a dynamic balance between the host's immune system and the tumor. At present, solid tumors are treated primarily by surgical resection combined with radiotherapy and chemotherapy, a treatment process that is painful and not always effective. With advantages over traditional treatments, the recently developed CAR-T immunotherapy has been applied and has shown highly promising results. Nevertheless, the complexity of solid tumors presents a great challenge to this technique. This review focuses on elucidating the factors influencing the anti-tumor effects of CAR-T in the specific tumor environment, and hence exploring feasible approaches to overcome them.

Cytokine Release Syndrome with Chimeric Antigen Receptor T Cell Therapy

Chimeric antigen receptor (CAR)-modified T cells (CAR-Ts) targeting CD19 have resulted in unprecedented durable remissions for patients with relapsed and refractory B cell malignancies. Cytokine release syndrome (CRS), resulting from rapid immune activation induced by CAR-Ts, is the most significant treatment-related toxicity. CRS initially manifests with fever and can progress to life-threatening capillary leak with hypoxia and hypotension. The clinical signs of CRS correlate with T cell activation and high levels of cytokines including IL-6. Tocilizumab, an anti-IL-6 receptor antagonist, is the standard for CRS management, but optimal timing of administration is unclear. The development of a supportive infrastructure by treatment centers is important to maintain safe administration as access expands. Collaborative efforts are underway to harmonize the definition and grading of CRS to allow for better interpretation of toxicities across CAR-T products and clinical trials and allow for informed management algorithms.

Direct visualization of single-molecule membrane protein interactions in living cells

Interactions between membrane proteins are poorly understood despite their importance in cell signaling and drug development. Here, we present a co-immunoimmobilization assay (Co-II) enabling the direct observation of membrane protein interactions in single living cells that overcomes the limitations of currently prevalent proximity-based indirect methods. Using Co-II, we investigated the transient homodimerizations of epidermal growth factor receptor (EGFR) and beta-2 adrenergic receptor (β2-AR) in living cells, revealing the differential regulation of these receptors’ dimerizations by molecular conformations and microenvironment in a plasma membrane. Co-II should provide a simple, rapid, and robust platform for visualizing both weak and strong protein interactions in the plasma membrane of living cells.

Protein–protein interactions govern cellular processes. The majority of these physical interactions previously identified are strong/permanent interactions, which typically remain unbroken even after purification. The weak/transient interactions between proteins have been implicated in the control of dynamic cellular process that maintain cellular homeostasis and trigger signaling cascades upon environmental changes. However, these interactions are poorly investigated, mainly due to the methodological limitations. Here, we have developed a co-immunoimmobilization assay called Co-II that enables the direct visualization of protein–protein interactions in the membrane of living cells at the single-molecule level. Co-II is based on the intuitive concept that if the protein of interest is immobilized, the interacting protein must be co-immobilized. The use of intrinsic protein diffusivity fundamentally overcomes the limitations of proximity-based methods. Using Co-II, we study the transient homodimerizations of EGFR and β2-AR in living cells, which have been implicated in several types of cancers and heart diseases. We show that the dimerization of these receptors is differently regulated by molecular conformations and the microenvironment in the plasma membrane.

Leucine-rich repeat-containing G-protein coupled receptor 5 enriched organoids under chemically-defined growth conditions

An organoid is a complex, multi-cell three-dimensional (3D) structure that contains tissue-specific cells. Epithelial stem cells, which are marked by leucine-rich repeat-containing G-protein coupled receptor 5 (Lgr5), have the potential for self-renewal and expansion as organoids. However, in the case of intestinal organoids from Lgr5-EGFP-IRES-CreERT2 transgenic mice, in vitro expansion of the Lgr5 expression is limited in a culture condition supplemented with essential proteins, such as epidermal growth factor (E), noggin (N), and R-spondin 1 (R). In this study, we hypothesized that self-renewal of Lgr5+ stem cells in a 3D culture system can be stimulated by defined compounds (CHIR99021, Valproic acid, Y-27632, and A83-01). Our results demonstrated that dissociated single cells from organoids were organized into a 3D structure in the four compounds containing the ENR culture medium in a 3D and two-dimensional (2D) culture system. Moreover, the Lgr5 expression level of organoids from the ENR- and compound-containing media increased. Furthermore, the conversion of cultured Lgr5+ stem cells from 2D to 3D was confirmed. Therefore, defined compounds promote the expansion of Lgr5+ stem cells in organoids.

Self-Adjusting Cytokine Neutralizer Cells as a Closed-Loop Delivery System of Anti-Inflammatory Biologicals

The cytokines tumor necrosis factor α (TNFα) and interleukin 1 β (IL-1β) are both strong NF-κB activators and some of the first cytokines to be released in an inflammatory process. TNFα and IL-1β are present in many autoimmune diseases, such as rheumatoid arthritis (RA). TNFα and IL-1β-blocking therapies are quite successful and established in the treatment of RA, but may also be promising in other diseases. For the treatment of recurring autoimmune diseases, strong controlled sensor-effector cells inhibiting TNFα or IL-1β appear highly predestined. Such cells detect a disease biomarker and autonomously react with the dose-dependent production of therapeutic proteins. Hence, we aim to harness and assemble the interactions of TNFα, IL-1β, and NF-κB, which are an ideal match for synthetic biology-based circuits to rewire the transmission to approved TNFα- or IL-1β-blocking biologicals. Considering the high impact of environmental influences on the dynamics of cell-based systems, we established closed-loop controllable cytokine neutralizer cells, monitoring cytokine levels and autonomously delivering powerful biologicals. This real-time processing system may provide dose-dependent drug delivery, which may be tailored for prospective cell and gene therapies against RA, and may offer a more personalized medicine than calculated drug dosing based on body weight.

Carbohydrate Targets for CAR T Cells in Solid Childhood Cancers

Application of the CAR targeting strategy in solid tumors is challenged by the need for adequate target antigens. As a consequence of their tissue origin, embryonal cancers can aberrantly express membrane-anchored gangliosides. These are carbohydrate molecules consisting of a glycosphingolipid linked to sialic acids residues. The best-known example is the abundant expression of ganglioside G_D2 on the cell surface of neuroblastomas which derive from G_D2-positive neuroectoderm. Gangliosides are involved in various cellular functions, including signal transduction, cell proliferation, differentiation, adhesion and cell death. In addition, transformation of human cells to cancer cells can be associated with distinct glycosylation profiles which provide advantages for tumor growth and dissemination and can serve as immune targets. Both gangliosides and aberrant glycosylation of proteins escape the direct molecular and proteomic screening strategies currently applied to identify further immune targets in cancers. Due to their highly restricted expression and their functional roles in the malignant behavior, they are attractive targets for immune engineering strategies. G_D2-redirected CAR T cells have shown activity in clinical phase I/II trials in neuroblastoma and next-generation studies are ongoing. Further carbohydrate targets for CAR T cells in preclinical development are O-acetyl-G_D2, NeuGc-GM3 (N-glycolyl GM3), G_D3, SSEA-4, and oncofetal glycosylation variants. This review summarizes knowledge on the role and function of some membrane-expressed non-protein antigens, including gangliosides and abnormal protein glycosylation patterns, and discusses their potential to serve as a CAR targets in pediatric solid cancers.

Making CAR T Cells a Solid Option for Solid Tumors

Adoptive cell therapy with chimeric antigen receptor (CAR) T cells aims to redirect the patient's own immune system to selectively attack cancer cells. To do so, CAR T cells are endowed with specific antigen recognition moieties fused to signaling and costimulatory domains. While this approach has shown great success for the treatment of B cell malignancies, response rates among patients with solid cancers are less favorable. The major challenges for CAR T cell immunotherapy in solid cancers are the identification of unique tumor target antigens, as well as improving CAR T cell trafficking to and expansion at the tumor site. This review focuses on combinatorial antigen targeting, regional delivery and approaches to improve CAR T cell persistence in the face of a hostile tumor microenvironment.

Engineering CAR-T Cells for Improved Function Against Solid Tumors

Genetic engineering T cells to create clinically applied chimeric antigen receptor (CAR) T cells has led to improved patient outcomes for some forms of hematopoietic malignancies. While this has inspired the biomedical community to develop similar strategies to treat solid tumor patients, challenges such as the immunosuppressive character of the tumor microenvironment, CAR-T cell persistence and trafficking to the tumor seem to limit CAR-T cell efficacy in solid cancers. This review provides an overview of mechanisms that tumors exploit to evade eradication by CAR-T cells as well as emerging approaches that incorporate genetic engineering technologies to improve CAR-T cell activity against solid tumors.

Conjugation of haematopoietic stem cells and platelets decorated with anti-PD-1 antibodies augments anti-leukaemia efficacy

Patients with acute myeloid leukaemia who relapse following therapy have few treatment options and face poor outcomes. Immune checkpoint inhibition, for example, by antibody-mediated programmed death-1 (PD-1) blockade, is a potent therapeutic modality that improves treatment outcomes in acute myeloid leukaemia. Here, we show that systemically delivered blood platelets decorated with anti-PD-1 antibodies (aPD-1) and conjugated to haematopoietic stem cells (HSCs) suppress the growth and recurrence of leukaemia in mice. Following intravenous injection into mice bearing leukaemia cells, the HSC-platelet-aPD-1 conjugate migrated to the bone marrow and locally released aPD-1, significantly enhancing anti-leukaemia immune responses, and increasing the number of active T cells, production of cytokines and chemokines, and survival time of the mice. This cellular conjugate also promoted resistance to re-challenge with leukaemia cells. Taking advantage of the homing capability of HSCs and in situ activation of platelets for the enhanced delivery of a checkpoint inhibitor, this cellular combination-mediated drug delivery strategy can significantly augment the therapeutic efficacy of checkpoint blockade.

Engineered Biosensors from Dimeric Ligand-Binding Domains

Biosensors are important components of many synthetic biology and metabolic engineering applications. Here, we report a second generation of Saccharomyces cerevisiae digoxigenin and progesterone biosensors based on destabilized dimeric ligand-binding domains that undergo ligand-induced stabilization. The biosensors, comprising one ligand-binding domain monomer fused to a DNA-binding domain and another fused to a transcriptional activation domain, activate reporter gene expression in response to steroid binding and receptor dimerization. The introduction of a destabilizing mutation to the dimer interface increased biosensor dynamic range by an order of magnitude. Computational redesign of the dimer interface and functional selections were used to create heterodimeric pairs with further improved dynamic range. A heterodimeric biosensor built from the digoxigenin and progesterone ligand-binding domains functioned as a synthetic "AND"-gate, with 20-fold stronger response to the two ligands in combination than to either one alone. We also identified mutations that increase the sensitivity or selectivity of the biosensors to chemically similar ligands. These dimerizing biosensors provide additional flexibility for the construction of logic gates and other applications.

Chimeric Antigen Receptors Based on Low Affinity Mutants of FcεRI Re-direct T Cell Specificity to Cells Expressing Membrane IgE

IgE is the key mediator of allergic responses. Omalizumab, an IgE-specific monoclonal antibody that depletes IgE, is effective for treating severe allergic asthma. The need for frequent administration of the expensive drug, however, limits its applications. Taking advantage of T cell memory, adoptive T cell therapy (ACT) targeting IgE-producing cells has the potential to achieve long-term suppression of IgE and relief of symptoms for severe allergic diseases. The transmembrane form of IgE (mIgE), which is present on all IgE-producing cells, serves as an excellent molecular target for ACT that employs chimeric antigen receptors (CARs). Here, we designed and tested CARs that use the extracellular domain of high affinity IgE receptor, FcεRIα, for mIgE recognition. When expressed on Jurkat T cells, FcεRIα-based CARs mediated robust responses in terms of CD69 upregulation to U266 myeloma cells expressing low levels of mIgE. FcεRIα-based CARs specifically recognized cells expressing mIgE, but not cells with secreted IgE captured through Fcε receptors. CAR⁺ Jurkat cells did not respond to LAD2 mast cells with secreted IgE bound through FcεRI or Ramos cells with secreted IgE bound through FcεRII. Co-culture of CAR⁺ Jurkat cells and LAD2 mast cells with IgE bound did not trigger LAD2 cell degranulation. The activity of CAR using wild type FcεRIα for mIgE binding was inhibited by the presence secreted IgE, which likely blocked CAR-mIgE interaction. The activities of CARs using low affinity mutants of FcεRIα, however, tolerated secreted IgE at relatively high concentrations. Moreover, primary human CD8⁺ T cells expressing a low affinity mutant CAR responded to U266 cells with INFγ production and cytotoxicity despite the presence of secreted IgE. The potency, specificity, and robustness of our CAR design, combined with repaid advances in the safety of ACT, hold promise for novel and highly effective cell-based therapies against severe allergic diseases.

Chemogenetic Tools for Causal Cellular and Neuronal Biology

Chemogenetic technologies enable selective pharmacological control of specific cell populations. An increasing number of approaches have been developed that modulate different signaling pathways. Selective pharmacological control over G protein-coupled receptor signaling, ion channel conductances, protein association, protein stability, and small molecule targeting allows modulation of cellular processes in distinct cell types. Here, we review these chemogenetic technologies and instances of their applications in complex tissues in vivo and ex vivo.

Anti-Multiple Myeloma Activity of Nanobody-Based Anti-CD38 Chimeric Antigen Receptor T Cells

Chimeric antigen receptor T cells (CAR-Ts) are a promising strategy for the treatment of many cancers, including multiple myeloma (MM), a hematological malignancy characterized by the high expression of CD38. To broaden the applications of using CD38 as a therapeutic target for the disease, we developed a new nanobody against CD38 and constructed a CD38-CAR that was composed of this nanobody as the targeting domain, and 4-1BB and CD3ζ as the costimulatory and activating domains, in a lentiviral vector. CD3⁺ T cells from healthy individuals were transduced with the CD38-CAR at an efficiency higher than 60%, as determined by CD38-CAR expression using flow cytometry. The CD38-CAR-Ts proliferated efficiently and produced more inflammatory cytokines, such as IL-2, IFN-γ, and TNF-α, when activated. The CD38-CAR-Ts effectively lysed CD38⁺ MM cell lines, including LP-1, RPMI 8226, OPM2, and MOLP8, and primary MM cells from multiple myeloma patients. The specificity was demonstrated by the fact that CD38-CAR-Ts showed little cytotoxicity on LP-1 cells with CD38 knocked out or on K562 cells, which do not express CD38. CD38-CAR-Ts appeared to have a very slight cytotoxicity against CD38⁺ fractions of T cells, B cells, and natural killer cells. In addition, the lysis of CD34⁺ hematopoietic progenitor cells did not completely inhibit the development of colony-forming units. In vivo, CD38-CAR-Ts inhibited tumor growth in NOD/SCID mice that were subcutaneously inoculated with RPMI 8226 cells. These results demonstrate that the CD38-CAR-Ts constructed with the anti-CD38 nanobody are a promising approach for the treatment of multiple myeloma.

The potential of CAR T therapy for relapsed or refractory pediatric and young adult B-cell ALL

Recent advancements in immunooncology have resulted in the generation of novel therapies such as chimeric antigen receptor (CAR) T cells, which have revolutionized the treatment of pediatric patients with relapsed or refractory B-cell acute lymphoblastic leukemia. The journey of tisagenlecleucel (formerly CTL019) from early preclinical success to the US Food and Drug Administration approval is summarized in this review. Strategies that are currently being investigated to improve the efficacy and safety profile of CAR T-cells are also explored, as well as the factors contributing to the present state of patient access to CAR T therapy.

Building upon the success of CART19: chimeric antigen receptor T cells for hematologic malignancies

Chimeric antigen receptor T cell (CART) therapy has dramatically changed the therapeutic prospects for B cell malignancies. Over the last decade CD19-redirected CART have demonstrated the ability to induce deep, long-lasting remissions and possibly cure patients with relapsing B cell neoplasms. Such impressive results with CART19 fostered efforts to expand this technology to other incurable malignancies that naturally do not express CD19, such as acute myeloid leukemia (AML), Hodgkin lymphoma (HL) and multiple myeloma (MM). However, to reach this goal, several hurdles have to be overcome, in particular: (i) the apparent lack of suitable targets as effective as CD19; (ii) the immunosuppressive tumor microenvironment; (iii) intra-tumoral heterogeneity and antigen-negative relapses. Therefore, new strategies that allow safer and more potent CART platforms are under development and may provide grounds for new exciting breakthroughs in the field.

Synthetic immunology: T-cell engineering and adoptive immunotherapy

During the past decades, the rapidly-evolving cancer is hard to be thoroughly eliminated even though the radiotherapy and chemotherapy do exhibit efficacy in some degree. However, a breakthrough appeared when the adoptive cancer therapy [1] was developed, especially T cells armed with chimeric antigen receptors (CARs) showed great potential in tumor clinical trials recently. CAR-T cells successfully elevated the efficiency and specificity of cytotoxicity. In this review, we will talk about the design of CAR and CAR-included combinatory therapeutic applications in the principles of systems and synthetic immunology.

Strategies to Address Chimeric Antigen Receptor Tonic Signaling

Adoptive cell transfer using chimeric antigen receptors (CAR) has emerged as one of the most promising new therapeutic modalities for patients with relapsed or refractory B-cell malignancies. Thus far, results in patients with advanced solid tumors have proven disappointing. Constitutive tonic signaling in the absence of ligand is an increasingly recognized complication when deploying these synthetic fusion receptors and can be a cause of poor antitumor efficacy, impaired survival, and reduced persistence in vivo In parallel, ligand-dependent tonic signaling can mediate toxicity and promote T-cell anergy, exhaustion, and activation-induced cell death. Here, we review the mechanisms underpinning CAR tonic signaling and highlight the wide variety of effects that can emerge after making subtle structural changes or altering the methodology of CAR transduction. We highlight strategies to prevent unconstrained tonic signaling and address its deleterious consequences. We also frame this phenomenon in the context of endogenous TCR tonic signaling, which has been shown to regulate peripheral tolerance, facilitate the targeting of foreign antigens, and suggest opportunities to coopt ligand-dependent CAR tonic signaling to facilitate in vivo persistence and efficacy. Mol Cancer Ther; 17(9); 1795-815. ©2018 AACR.

Chimeric Antigen Receptor T Cell Therapy: Challenges to Bench-to-Bedside Efficacy

Immunotherapy with T cells genetically modified to express chimeric Ag receptors (CARs) that target tumor-associated molecules have impressive efficacy in hematological malignancies. The field has now embraced the challenge of applying this approach to treat common epithelial malignancies, which make up the majority of cancer cases but evade immunologic attack by a variety of subversive mechanisms. In this study, we review the principles that have guided CAR T cell design and the extraordinary clinical results being achieved in B cell malignancies targeting CD19 with a single infusion of engineered T cells. This success has raised expectations that CAR T cells can be applied to solid tumors, but numerous obstacles must be overcome to achieve the success observed in hematologic cancers. Potential solutions driven by advances in genetic engineering, synthetic biology, T cell biology, and improved tumor models that recapitulate the obstacles in human tumors are discussed.

Immunological-based approaches for cancer therapy

The immunologic landscape of tumors has been continuously unveiled, providing a new look at the interactions between cancer cells and the immune system. Emerging tumor cells are constantly eliminated by the immune system, but some cells establish a long-term equilibrium phase leading to tumor immunoediting and, eventually, evasion. During this process, tumor cells tend to acquire more mutations. Bearing a high mutation burden leads to a greater number of neoantigens with the potential to initiate an immune response. Although many tumors evoke an immune response, tumor clearance by the immune system does not occur due to a suppressive tumor microenvironment. The mechanisms by which tumors achieve the ability to evade immunologic control vary. Understanding these differences is crucial for the improvement and application of new immune-based therapies. Much effort has been placed in developing in silico algorithms to predict tumor immunogenicity and to characterize the microenvironment via high-throughput sequencing and gene expression techniques. Each sequencing source, transcriptomics, and genomics yields a distinct level of data, helping to elucidate the tumor-based immune responses and guiding the fine-tuning of current and upcoming immune-based therapies. In this review, we explore some of the immunological concepts behind the new immunotherapies and the bioinformatic tools to study the immunological aspects of tumors, focusing on neoantigen determination and microenvironment deconvolution. We further discuss the immune-based therapies already in clinical use, those underway for future clinical application, the next steps in immunotherapy, and how the characterization of the tumor immune contexture can impact therapies aiming to promote or unleash immune-based tumor elimination.

[Treatment of central nervous system leukemia with CD19-chimeric antigen receptor T-cell immunotherapy: two cases report and literature review]

Objective: To explore the efficacy and safety of chimeric antigen receptor T (CAR-T) cells in the treatment of central nervous system leukemia (CNSL). Methods: Two leukemia patients with CNSL were treated with CD19-CAR-T cells. The process and results of the entire treatment is reported and related literature review is conducted. Results: The patients were diagnosed as acute myeloid leukemia (AML)-M(2) with B lymphoid antigen expression and B cell acute lymphoblastic leukemia(B-ALL) by morphology and immunophenotype assay. The immunophenotype was consistent with the abnormal manifestations of AML-M(2) and B-ALL. Their clinical manifestations and laboratory tests met the diagnostic criteria of CNSL. The diagnosis was clear and the two patients were treated with CD19-CAR-T cell immunotherapy. Central nervous system symptoms were relieved. The imaging abnormalities of patient one has disappeared but cytokines release syndrome (CRS) occurred during the treatment. Cerebrospinal fluid of patient two was negative and no obvious CRS reaction was found. Conclusions: CAR-T cell immunotherapy is likely to induce the remission of CNSL and improve the prognosis.

Recombination of a dual-CAR-modified T lymphocyte to accurately eliminate pancreatic malignancy

Background

The therapeutic application of T cells endowing with chimeric antigen receptors (CARs) is faced with “on-target, off-tumor” toxicity against solid tumors, particularly in the treatment of the pancreatic cancer. To our best knowledge, the pancreatic cancer cell line AsPC-1 often highly expressed some distinct tumor-associated antigens, such as carcino-embryonic antigen (CEA) and mesothelin (MSLN). Therefore, in this research, we have characterized dual-receptor CAR-modified T cells (dCAR-T) that exert effective and safe cytotoxicity against AsPC-1 cells.

Methods

Based on the dual signaling pathway of wild T cells, we designed a novel dCAR diagram specific for CEA and MSLN, which achieved comparable activity relative to that of conventional CAR-T cells (CEA-CAR T or MSLN-CAR T). In this dCAR, a tandem construct containing two physically separate structures, CEA-CD3ζ and MSLN-4/1BB signaling domains were effectively controlled with tumor antigens CEA and MSLN, respectively. Finally, the activity of dCAR-T cells has been verified via in vitro and in vivo experiments.

Results

In the presence of cognate tumor cells (AsPC-1) expressing both CEA and MSLN, dCAR-T cells exerted high anti-tumor activity relative to that of other single-receptor CAR-T cells bearing only one signaling pathway (e.g., Cζ-CAR and MBB-CAR). In a xenograft model, dCAR-T cells significantly inhibited the growth of AsPC-1 cells yet no effect on the growth of non-cognate tumor cells. Furthermore, the released cytokines and T cell persistence in mice were comparable with that of conventional CAR-T cells, obtaining specific and controllable cytotoxicity.

Conclusions

A novel type of CAR-T cells, termed dCAR-T, was designed with specific activities, that is, significant cytotoxicity for two antigen-positive tumor cells yet no cytotoxicity for single antigen-positive tumor cells. Dual-targeted CAR-T cells can be precisely localized at the tumor site and can exert high cytotoxicity against tumor cells, alleviating “on-target, off-tumor” toxicity and enabling accurate application of CAR-T cell therapy.

Electronic supplementary material

The online version of this article (10.1186/s13045-018-0646-9) contains supplementary material, which is available to authorized users.

Targeting B Cell Maturation Antigen (BCMA) in Multiple Myeloma: Potential Uses of BCMA-Based Immunotherapy

The approval of the first two monoclonal antibodies targeting CD38 (daratumumab) and SLAMF7 (elotuzumab) in late 2015 for treating relapsed and refractory multiple myeloma (RRMM) was a critical advance for immunotherapies for multiple myeloma (MM). Importantly, the outcome of patients continues to improve with the incorporation of this new class of agents with current MM therapies. However, both antigens are also expressed on other normal tissues including hematopoietic lineages and immune effector cells, which may limit their long-term clinical use. B cell maturation antigen (BCMA), a transmembrane glycoprotein in the tumor necrosis factor receptor superfamily 17 (TNFRSF17), is expressed at significantly higher levels in all patient MM cells but not on other normal tissues except normal plasma cells. Importantly, it is an antigen targeted by chimeric antigen receptor (CAR) T-cells, which have already shown significant clinical activities in patients with RRMM who have undergone at least three prior treatments, including a proteasome inhibitor and an immunomodulatory agent. Moreover, the first anti-BCMA antibody–drug conjugate also has achieved significant clinical responses in patients who failed at least three prior lines of therapy, including an anti-CD38 antibody, a proteasome inhibitor, and an immunomodulatory agent. Both BCMA targeting immunotherapies were granted breakthrough status for patients with RRMM by FDA in Nov 2017. Other promising BCMA-based immunotherapeutic macromolecules including bispecific T-cell engagers, bispecific molecules, bispecific or trispecific antibodies, as well as improved forms of next generation CAR T cells, also demonstrate high anti-MM activity in preclinical and even early clinical studies. Here, we focus on the biology of this promising MM target antigen and then highlight preclinical and clinical data of current BCMA-targeted immunotherapies with various mechanisms of action. These crucial studies will enhance selective anti-MM response, transform the treatment paradigm, and extend disease-free survival in MM.

Steering CAR T cells to distinguish friend from foe

CD19-specific chimeric antigen receptor (CAR)⁺ T cells have demonstrated clinical efficacy and long-lasting remissions, concomitant with tolerable normal B-cell aplasia. However, many tumor-associated antigens (TAAs) are expressed on normal tissues, the destruction of which would lead to intolerable toxicity. Thus, there is a need to engineer CAR⁺ T cells with improved safety profiles to restrict toxicity against TAA-expressing normal tissues. Bioengineering approaches include: (i) targeting CAR⁺ T cells to the tumor site, (ii) limiting CAR⁺ T-cell persistence, and (iii) restricting CAR activation. We review and evaluate strategies to engineer CAR⁺ T cells to reduce the potential of on-target, off-tissue toxicity.

Chimeric antigen receptor-engineered T-cell therapy for liver cancer

BACKGROUND

Chimeric antigen receptor-engineered T-cell (CAR-T) therapy is a newly developed immunotherapy used in the treatment of cancers. Because CAR-T therapy has shown great success in treating CD19-positive hematological malignancies, its application has been explored in the treatment of solid tumors, such as liver cancer. In this review, we discuss the immune characteristics of liver cancer, the obstacles encountered during the application of CAR-T therapy, and preclinical and clinical progress in the use of CAR-T therapy in patients with liver cancer.

DATA SOURCES

The data on CAR-T therapy related to liver cancers were collected by searching PubMed and the Web of Science databases prior to December 2017 with the keywords "chimeric antigen receptor", "CAR-T", "liver cancer", "hepatocellular carcinoma", and "solid tumor". Additional articles were identified by manual search of references found in the primary articles. The data for clinical trials were collected by searching ClinicalTrials.gov.

RESULTS

The liver has a tolerogenic nature in the intrahepatic milieu and its tumor microenvironment significantly affects tumor progression. The obstacles that reduce the efficacy of CAR-T therapy in solid tumors include a lack of specific tumor antigens, limited trafficking and penetration of CAR-T cells to tumor sites, and an immunosuppressive tumor microenvironment. To overcome these obstacles, several strategies have emerged. In addition, several strategies have been developed to manage the side effects of CAR-T, including enhancing the selectivity of CARs and controlling CAR-T activity. To date, no clinical trials of CAR-T therapy against HCC have been completed. However, preclinical studies in vitro and in vivo have shown potent antitumor efficacy. Glypican-3, mucin-1, epithelial cell adhesion molecule, carcinoembryonic antigen, and other targets are currently being studied.

CONCLUSIONS

The application of CAR-T therapy for liver cancer is just beginning to be explored and more research is needed. However, we are optimistic that CAR-T therapy will offer a new approach for the treatment of liver cancers in the future.

Engineering Platforms for T Cell Modulation

T cells are crucial contributors to mounting an effective immune response and increasingly the focus of therapeutic interventions in cancer, infectious disease, and autoimmunity. Translation of current T cell immunotherapies has been hindered by off-target toxicities, limited efficacy, biological variability, and high costs. As T cell therapeutics continue to develop, the application of engineering concepts to control their delivery and presentation will be critical for their success. Here, we outline the engineer's toolbox and contextualize it with the biology of T cells. We focus on the design principles of T cell modulation platforms regarding size, shape, material, and ligand choice. Furthermore, we review how application of these design principles has already impacted T cell immunotherapies and our understanding of T cell biology. Recent, salient examples from protein engineering, synthetic particles, cellular and genetic engineering, and scaffolds and surfaces are provided to reinforce the importance of design considerations. Our aim is to provide a guide for immunologists, engineers, clinicians, and the pharmaceutical sector for the design of T cell-targeting platforms.

Eradication of Established Tumors by Chemically Self-Assembled Nanoring Labeled T Cells

Our laboratory has developed chemically self-assembled nanorings (CSANs) as prosthetic antigen receptors (PARs) for the nongenetic modification of T cell surfaces. PARs have been successfully employed in vitro to activate T cells for the selective killing of leukemia cells. However, PAR efficacy has yet to be evaluated in vivo or against solid tumors. Therefore, we developed bispecific PARs that selectively target the human CD3 receptor and human epithelial cell adhesion molecule (EpCAM), which is overexpressed on multiple carcinomas and cancer stem cells. The αEpCAM/αCD3 PARs were found to stably bind T cells for >4 days, and treating EpCAM⁺ MCF-7 breast cancer cells with αEpCAM/αCD3 PAR-functionalized T cells resulted in the induction of IL-2, IFN-γ, and MCF-7 cytotoxicity. Furthermore, an orthotopic breast cancer model validated the ability of αEpCAM/αCD3 PAR therapy to direct T cell lytic activity toward EpCAM⁺ breast cancer cells in vivo, leading to tumor eradication. In vivo biodistribution studies demonstrated that PAR-T cells were formed in vivo and persist for over 48 h with rapid accumulation in tumor tissue. Following PAR treatment, the production of IL-2, IFN-γ, IL-6, and TNF-α could be significantly reduced by an infusion of clinically relevant concentrations of the FDA-approved antibiotic, trimethoprim, signaling pharmacologic PAR deactivation. Importantly, CSANs did not induce naïve T cell activation and thus exhibit a limited potential to induce naïve T cell anergy. In addition, murine immunogenicity studies demonstrated that CSANs do not induce a significant antibody response nor do they activate splenic cells. Collectively, our results demonstrate that bispecific CSANs are able to nongenetically generate reversibly modified T cells that are capable of eradicating targeted solid tumors.

A chemically induced proximity system engineered from the plant auxin signaling pathway

Methods based on chemically induced proximity (CIP) serve as powerful tools to control cellular processes in a temporally specific manner. To expand the repertoire of CIP systems available for studies of cellular processes, we engineered the plant auxin signaling pathway to create a new indole-3-acetic acid (IAA) based CIP method. Auxin-induced protein degradation that occurs in the natural pathway was eliminated in the system. The new IAA based method is both readily inducible and reversible, and used to control the production of therapeutic proteins that induced the apoptosis of cancer cells. The approach is also orthogonal to existing CIP systems and used to construct a biological Boolean logic gate controlling gene expression system. We believe that the new CIP method will be applicable to the artificial control and dissection of complex cellular functions.

Traceable Bioinspired Nanoparticle for the Treatment of Metastatic Breast Cancer via NIR-Trigged Intracellular Delivery of Methylene Blue and Cisplatin

Cytotoxic T lymphocyte (CTL) eliminates abnormal cells through target recognition-triggered intracellular toxin delivery. Chimeric antigen receptor T-cell improves cancer cell recognition of CTL, but its effectiveness and safety in solid tumor treatment are still hampered by poor tumor infiltration, suppressive tumor microenvironment, and severe on-target off-tumor toxicity. Given the functionality and challenges of CTL in cancer therapy, herein, a CTL-inspired nanovesicle (MPV) with a cell membrane-derived shell and a methylene blue (MB) and cisplatin (Pt) loaded gelatin nanogel core is created. The MPV generates contrast for tumor photoacoustic imaging, and produces hyperthermia upon laser irradiation, enabling photothermal imaging and deep tumor penetration. Meanwhile, it releases MB and Pt, and then delivers them into the cytosol of cancer cells, which process can be visualized by imaging the recovery of MB-derived fluorescence. The localized hyperthermia, photodynamic therapy, and chemotherapy together kill 4T1 breast cancer cells effectively, resulting in primary tumor regression and 97% inhibition of pulmonary metastasis, without significant toxicity to the animals. Taken together, the MPV shows tumor-specific and stimuli-triggered intracellular toxin delivery with advantages in traceable accumulation and activation, high tumor penetration, and triple combination therapy, and thus can be an effective nanomedicine for combating metastatic breast cancer.

Manipulating the tumor microenvironment by adoptive cell transfer of CAR T-cells

T-cells expressing synthetic chimeric antigen receptors (CARs) have revolutionized immuno-oncology and highlighted the use of adoptive cell transfer, for the treatment of cancer. The phenomenal clinical success obtained in the treatment of hematological malignancies with CAR T-cells has not been reproduced in the treatment of solid tumors, mainly due to the suppressive and hostile tumor microenvironment (TME). This review will address the immunosuppressive features of the TME, which include the stroma, cytokine and chemokine milieu, suppressive regulatory cells and hypoxic conditions, which can all pose formidable barriers for the effective anti-tumor function of CAR T-cells. Some of the novel next generation CARs that have been developed and tested against the TME, will be discussed, to highlight the status of current research in CAR T-cell therapy for solid tumors.

Enhancing T cell therapy through TCR-signaling-responsive nanoparticle drug delivery

Adoptive cell therapy (ACT) with antigen-specific T cells has shown remarkable clinical success, but approaches to safely and effectively augment T cell function, especially in solid tumors, remain of great interest. Here we describe a strategy to “backpack” large quantities of supporting protein drugs on T cells using protein nanogels (NGs) that selectively release these cargos in response to T cell receptor (TCR) activation. We design cell surface-conjugated NGs that respond to an increase in T cell surface reduction potential upon antigen recognition, limiting drug release to sites of antigen encounter such as the tumor microenvironment. Using NGs carrying an IL-15 superagonist complex, we demonstrate that relative to systemic administration of free cytokines, NG delivery selectively expands T cells 16-fold in tumors, and allows at least 8-fold higher doses of cytokine to be administered without toxicity. The improved therapeutic window enables substantially increased tumor clearance by murine T cell and human CAR-T cell therapy in vivo.

Mechanisms regulating T-cell infiltration and activity in solid tumors

T-lymphocytes play a critical role in cancer immunity as evidenced by their presence in resected tumor samples derived from long-surviving patients, and impressive clinical responses to various immunotherapies that reinvigorate them. Indeed, tumors can upregulate a wide array of defense mechanisms, both direct and indirect, to suppress the ability of Tcells to reach the tumor bed and mount curative responses upon infiltration. In addition, patient and tumor genetics, previous antigenic experience, and the microbiome, are all important factors in shaping the T-cell repertoire and sensitivity to immunotherapy. Here, we review the mechanisms that regulate T-cell homing, infiltration, and activity within the solid tumor bed. Finally, we summarize different immunotherapies and combinatorial treatment strategies that enable the immune system to overcome barriers for enhanced tumor control and improved patient outcome.

Chemogenetic control of gene expression and cell signaling with antiviral drugs

We developed a method in which the NS3 cis-protease from hepatitis C virus can be used as a ligand-inducible connection to control the function and localization of engineered proteins in mammalian cells. To demonstrate the versatility of this approach, we designed drug-sensitive transcription factors and transmembrane signaling proteins, the activities of which can be tightly and reversibly controlled through the use of clinically tested antiviral protease inhibitors.

Pre-clinical development of chimeric antigen receptor T-cell immunotherapy: Implications of design for efficacy and safety

Following the landmark approvals by the United States Food and Drug Administration, the adoptive transfer of CD19-directed chimeric antigen receptor (CAR) T-cells has now entered mainstream clinical practice for patients with chemotherapy-resistant or refractory B-cell malignancies. These approvals have followed on from a prolonged period of pre-clinical evaluation, informing the design of clinical trials that have demonstrated unprecedented efficacy in this difficult to treat patient population. However, the delivery of autologous CAR-engineered T-cell therapy is complex, costly and not without significant risk. Here we summarize the key themes of CAR T-cell preclinical development and highlight a number of innovative strategies designed to further address toxicity and improve efficacy. In concert with the emerging promise of precision genome editing, it is hoped these next generation products will increase the repertoire of clinical applications of CAR T-cell therapy in malignant and perhaps other disease settings.

Bi-specific ligand-controlled chimeric antigen receptor T-cell therapy for non-small cell lung cancer

Our goal is to develop a switch-controlled approach to enable better control of reactivity and safety of chimeric antigen receptor (CAR)-T therapy for non-small-cell lung cancer (NSCLC). Lentiviral transduction was performed to generate anti-FITC CAR-T cells and target cells stably expressing either isoform of the folate receptor. Colorimetric-based cytotoxic assay, enzyme-linked immunosorbent assay, and multiparametric flow cytometry analysis were used to evaluate the specificity and activity of CAR-T cells in vitro. Human primary T cells stably expressing the fully human anti-FITC CAR were generated. Anti-FITC CAR-T cells displayed antigen-specific and folate-FTIC dependent reactivity against engineered A549-FRα and THP-1-FRβ. The selective activation and proliferation of anti-FITC CAR-T cells in vitro stringently relied on the co-existence of folate-FITC and FR- expressing target cells and was dose-titratable with the folate-FITC switch. The excellent in vitro efficacy and specificity of an adaptor-controlled CAR-T therapy to target both tumor cells and tumor-associated macrophages in NSCLCs were validated.