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

The role of bone marrow microenvironment on CAR-T efficacy in haematologic malignancies

In recent years, chimeric antigen receptor-T (CAR-T) cell therapy has emerged as a novel immunotherapy method. It has shown significant therapeutic efficacy in the treatment of haematological B cell malignancies. In particular, the CAR-T therapy targeting CD19 has yielded unprecedented efficacy for acute B-lymphocytic leukaemia (B-ALL) and non-Hodgkin's lymphoma (NHL). In haematologic malignancies, tumour stem cells are more prone to stay in the regulatory bone marrow (BM) microenvironment (called niches), which provides a protective environment against immune attack. However, how the BM microenvironment affects the anti-tumour efficacy of CAR-T cells and its underlying mechanism is worthy of attention. In this review, we discuss the role of the BM microenvironment on the efficacy of CAR-T in haematological malignancies and propose corresponding strategies to enhance the anti-tumour activity of CAR-T therapy.

T cell effects and mechanisms in immunotherapy of head and neck tumors

Head and neck tumors (HNCs) are a common tumor in otorhinolaryngology head and neck surgery, accounting for 5% of all malignant tumors in the body and are the sixth most common malignant tumor worldwide. In the body, immune cells can recognize, kill, and remove HNCs. T cell-mediated antitumor immune activity is the most important antitumor response in the body. T cells have different effects on tumor cells, among which cytotoxic T cells and helper T cells play a major killing and regulating role. T cells recognize tumor cells, activate themselves, differentiate into effector cells, and activate other mechanisms to induce antitumor effects. In this review, the immune effects and antitumor mechanisms mediated by T cells are systematically described from the perspective of immunology, and the application of new immunotherapy methods related to T cells are discussed, with the objective of providing a theoretical basis for exploring and forming new antitumor treatment strategies. Video Abstract.

Adoptive tumor infiltrating lymphocytes cell therapy for cervical cancer

Cervical cancer is one of the most common malignancies among females. As a virus-related cancer, cervical cancer has attracted a lot of attention to develop virus-targeted immune therapy, including vaccine and adoptive immune cell therapy (ACT). Adoptive tumor infiltrating lymphocytes (TILs) cell therapy has been found to be able to control advanced disease progression in some cervical cancer patients who have received several lines of treatment in a pilot clinical trial. In addition, sustainable therapeutic effect has been identified in some cases. The safety risks of TIL therapy for patients are minimal or at least manageable. In this review, we focused on the versatility of TILs and tried to summarize potential strategies to improve the therapeutic effect of TILs and discuss related perspectives.

TCR-engineered iNKT cells induce robust antitumor response by dual targeting cancer and suppressive myeloid cells

Adoptive immunotherapy with T cells engineered with tumor-specific T cell receptors (TCRs) holds promise for cancer treatment. However, suppressive cues generated in the tumor microenvironment (TME) can hinder the efficacy of these therapies, prompting the search for strategies to overcome these detrimental conditions and improve cellular therapeutic approaches. CD1d-restricted invariant natural killer T (iNKT) cells actively participate in tumor immunosurveillance by restricting suppressive myeloid populations in the TME. Here, we showed that harnessing iNKT cells with a second TCR specific for a tumor-associated peptide generated bispecific effectors for CD1d- and major histocompatibility complex (MHC)-restricted antigens in vitro. Upon in vivo transfer, TCR-engineered iNKT (TCR-iNKT) cells showed the highest efficacy in restraining the progression of multiple tumors that expressed the cognate antigen compared with nontransduced iNKT cells or CD8+ T cells engineered with the same TCR. TCR-iNKT cells achieved robust cancer control by simultaneously modulating intratumoral suppressive myeloid populations and killing malignant cells. This dual antitumor function was further enhanced when the iNKT cell agonist α-galactosyl ceramide (α-GalCer) was administered as a therapeutic booster through a platform that ensured controlled delivery at the tumor site, named multistage vector (MSV). These preclinical results support the combination of tumor-redirected TCR-iNKT cells and local α-GalCer boosting as a potential therapy for patients with cancer.

Graft-Versus-Solid-Tumor Effect: From Hematopoietic Stem Cell Transplantation to Adoptive Cell Therapies

After allogeneic hematopoietic stem cell transplantation (HSCT), donor lymphocytes may contribute to the regression of hematological malignancies and select solid tumors, a phenomenon referred to as the graft-versus-tumor effect (GVT). However, this immunologic reaction is frequently limited by either poor specificity resulting in graft-versus-host disease or the frequency of tumor-specific T cells being too low to induce a complete and sustained anti-tumor response. Over the past 2 decades, it has become clear that the driver of GVT following allogeneic HSCT is T-cell-mediated recognition of antigens presented on tumor cells. With that regard, even though the excitement for using HSCT in solid tumors has declined, clinical trials of HSCT in solid tumors provided proof of concept and valuable insights leading to the discovery of tumor antigens and the development of targeted adoptive cell therapies for cancer. In this article, we review the results of clinical trials of allogeneic HSCT in solid tumors. We focus on lessons learned from correlative studies of these trials that hold the potential for the creation of tumor-specific immunotherapies with greater efficacy and safety for the treatment of malignancies.

Therapeutic applications of engineered chimeric antigen receptors-T cell for cancer therapy

Background

Findings of new targeted treatments with adequate safety evaluations are essential for better cancer cures and mortality rates. Immunotherapy holds promise for patients with relapsed disease, with the ability to elicit long-term remissions. Emerging promising clinical results in B-cell malignancy using gene-altered T-lymphocytes uttering chimeric antigen receptors have sparked a lot of interest. This treatment could open the path for a major difference in the way we treat tumors that are resistant or recurring.

Main body

Genetically altered T cells used to produce tumor-specific chimeric antigen receptors are resurrected fields of adoptive cell therapy by demonstrating remarkable success in the treatment of malignant tumors. Because of the molecular complexity of chimeric antigen receptors-T cells, a variety of engineering approaches to improve safety and effectiveness are necessary to realize larger therapeutic uses. In this study, we investigate new strategies for enhancing chimeric antigen receptors-T cell therapy by altering chimeric antigen receptors proteins, T lymphocytes, and their relations with another solid tumor microenvironment (TME) aspects. Furthermore, examine the potential region of chimeric antigen receptors-T cells therapy to become a most effective treatment modality, taking into account the basic and clinical and practical aspect.

Short conclusions

Chimeric antigen receptors-T cells have shown promise in the therapy of hematological cancers. Recent advancements in protein and cell editing, as well as genome-editing technologies, have paved the way for multilayered T cell therapy techniques that can address numerous important demands. At around the same time, there is crosstalk between various intended aspects within the chimeric antigen receptors-T cell diverse biological complexity and possibilities. These breakthroughs substantially improve the ability to comprehend these complex interactions in future solid tumor chimeric antigen receptor-T cell treatment and open up new treatment options for patients that are currently incurable.

A Dual Functional Drug Delivery System that Combines Photothermal Therapy and Immunotherapy to Treat Tumors

Cancer is one of the main diseases threatening human health. Immunotherapy, in which cancer is treated by activating immune cells and inducing the body's immune response, has rapidly developed. Photothermal therapy (PTT), a new treatment method that ablates tumors by light irradiation, has attracted great attention for its good therapeutic effect and low toxic side effects. In the present study, we combined photothermal and immunotherapy to design a novel nanoparticle delivery system by loading indoleamine 2,3-dioxygenase (IDO) inhibitors and toll-like receptor (TLR) agonists into polydopamine (PDA) nanoparticles coated with polyethylene imine (PEI). This delivery system has the advantages of high homogeneity, good stability, excellent biocompatibility, and low toxicity. In vitro antitumor studies showed that the system effectively inhibited the proliferation of mouse breast carcinoma cells and induced cell apoptosis. From the in vivo studies, we found that the system inhibited the growth of mouse breast carcinoma, facilitated the maturation of antigen-presenting cells, promoted T lymphocyte differentiation, and induced the body's immune response. The present study developed a dual functional drug delivery system combining photothermal therapy and immunotherapy to efficiently improve antitumor therapy with potential clinical application.

Myeloid and Mesenchymal Stem Cell Therapies for Solid Organ Transplant Tolerance

Transplantation is now performed globally as a routine procedure. However, the increased demand for donor organs and consequent expansion of donor criteria has created an imperative to maximize the quality of these gains. The goal is to balance preservation of allograft function against patient quality-of-life, despite exposure to long-term immunosuppression. Elimination of immunosuppressive therapy to avoid drug toxicity, with concurrent acceptance of the allograft-so-called operational tolerance-has proven elusive. The lack of recent advances in immunomodulatory drug development, together with advances in immunotherapy in oncology, has prompted interest in cell-based therapies to control the alloimmune response. Extensive experimental work in animals has characterized regulatory immune cell populations that can induce and maintain tolerance, demonstrating that their adoptive transfer can promote donor-specific tolerance. An extension of this large body of work has resulted in protocols for manufacture, as well as early-phase safety and feasibility trials for many regulatory cell types. Despite the excitement generated by early clinical trials in autoimmune diseases and organ transplantation, there is as yet no clinically validated, approved regulatory cell therapy for transplantation. In this review, we summarize recent advances in this field, with a focus on myeloid and mesenchymal cell therapies, including current understanding of the mechanisms of action of regulatory immune cells, and clinical trials in organ transplantation using these cells as therapeutics.

Blockade of TGF-βR improves the efficacy of doxorubicin by modulating the tumor cell motility and affecting the immune cells in a melanoma model

TGF-β contributes to drug resistance and the invasiveness of tumor cells and weakens the anti-tumor immune responses. The present study aimed at examining the efficacy of the combination of SB431542, as a specific inhibitor of TGF-βR, and doxorubicin in controlling the melanoma tumor in mice. The impact of the combination of the doxorubicin and SB431542 on the cell growth, apoptosis, migration, and invasiveness of B16-F10 cells was examined. Besides, the B16-F10 tumor was induced in C57BL/6 mice, and the effects of the mentioned treatment on the tumor volume, survival, and the exhaustion state of T cells were evaluated. Although the combination of doxorubicin and SB431542 did not exhibit synergism in the inhibition of cell growth and apoptosis induction, it efficiently prohibited the migration and the epithelial to mesenchymal transition of B16-F10 cells, and the combination of doxorubicin and SB431542 caused an increase in mRNA levels of E-cadherin and, on the other hand, led to a decline in the expression of Vimentin. Tumor volume and the survival of tumor-bearing mice were efficiently controlled by the combination therapy. This treatment also eventuated in a decrease in the percentage of PD-L1⁺, TCD4⁺, and TCD8⁺ cells as indicators of exhausted T cells within the spleens of tumor-bearing mice. Blockade of TGF-βR also propelled the RAW 264.7 cells towards an anti-tumor M1 macrophage phenotype. The inhibition of TGF-βR demonstrated a potential to increase the efficacy of doxorubicin chemotherapy by the means of affecting cellular motility and restoring the anti-tumor immune responses.

TGF-β/IL-7 Chimeric Switch Receptor-Expressing CAR-T Cells Inhibit Recurrence of CD19-Positive B Cell Lymphoma

Chimeric antigen receptor (CAR)-T cells are effective in the treatment of hematologic malignancies but have shown limited efficacy against solid tumors. Here, we demonstrated an approach to inhibit recurrence of B cell lymphoma by co-expressing both a human anti-CD19-specific single-chain variable fragment (scFv) CAR (CD19 CAR) and a TGF-β/IL-7 chimeric switch receptor (tTRII-I7R) in T cells (CD19 CAR-tTRII-I7R-T cells). The tTRII-I7R was designed to convert immunosuppressive TGF-β signaling into immune-activating IL-7 signaling. The effect of TGF-β on CD19 CAR-tTRII-I7R-T cells was assessed by western blotting. Target-specific killing by CD19 CAR-tTRII-I7R-T cells was evaluated by Eu-TDA assay. Daudi tumor-bearing NSG (NOD/SCID/IL2Rγ^-/-) mice were treated with CD19 CAR-tTRII-I7R-T cells to analyze the in vivo anti-tumor effect. In vitro, CD19 CAR-tTRII-I7R-T cells had a lower level of phosphorylated SMAD2 and a higher level of target-specific cytotoxicity than controls in the presence of rhTGF-β1. In the animal model, the overall survival and recurrence-free survival of mice that received CD19 CAR-tTRII-I7R-T cells were significantly longer than in control mice. These findings strongly suggest that CD19 CAR-tTRII-I7R-T cell therapy provides a new strategy for long-lasting, TGF-β-resistant anti-tumor effects against B cell lymphoma, which may lead ultimately to increased clinical efficacy.

Fibroblast Activation Protein (FAP)-Targeted CAR-T Cells: Launching an Attack on Tumor Stroma

Fibroblast activation protein (FAP) is a membrane protease that is highly expressed by cancer-associated fibroblasts (CAFs). FAP can modulate the tumor microenvironment (TME) by remodeling the extracellular matrix (ECM), and its overexpression on CAFs is associated with poor prognosis in various cancers. The TME is in part accountable for the limited efficacy of chimeric antigen receptor (CAR)-T cell therapy in treatment of solid tumors. Targeting FAP with CAR-T cells is one of the strategies being researched to overcome the challenges in the TME. This review describes the role of FAP in the TME and its potential as a target in CAR-T cell immunotherapy, summarizes the preclinical studies and clinical trials of anti-FAP-CAR-T cells to date, and reviews possible optimizations to augment their cytotoxic efficiency in solid tumors.

The Complexity of Targeting Chemokines to Promote a Tumor Immune Response

Immunotherapeutic treatment strategies greatly extend patient survival following malignant disease across a wide range of tumor types, including even those with metastatic disease. While diverse in approach, adoptive cell therapy, introduction of T cells that express chimeric antigen receptors, and checkpoint inhibitors all aim to re-invigorate the immune system to promote tumor cell identification and elimination. This review will focus on immune cell infiltration into tumors as well as a cellular organization within the tumor microenvironment as directed by the cell-specific expression patterns of chemokines and chemokine receptors. Through better understanding the chemokine network within tumors, we can uncover mechanisms to promote beneficial immune cell infiltration that can be combined with checkpoint inhibition. Conversely, chemokine expression is not limited to cells of the immune system, and it is understood that tumor cells also express chemokines and chemokine receptors. Tumor cells can hijack the chemokine networks to promote immune suppression and metastatic tumor cell trafficking. We will discuss the ways in which the chemokine network lies at the crossroad of immune evasion and tumor regression. Overall, this review will summarize key publications in the field of immune cell recruitment to tumors, highlight the dichotomous nature of chemokine interventions into cancer, and aims to identify therapeutic pathways forward.

Chemically Engineered Immune Cell-Derived Microrobots and Biomimetic Nanoparticles: Emerging Biodiagnostic and Therapeutic Tools

Over the past decades, considerable attention has been dedicated to the exploitation of diverse immune cells as therapeutic and/or diagnostic cell-based microrobots for hard-to-treat disorders. To date, a plethora of therapeutics based on alive immune cells, surface-engineered immune cells, immunocytes' cell membranes, leukocyte-derived extracellular vesicles or exosomes, and artificial immune cells have been investigated and a few have been introduced into the market. These systems take advantage of the unique characteristics and functions of immune cells, including their presence in circulating blood and various tissues, complex crosstalk properties, high affinity to different self and foreign markers, unique potential of their on-demand navigation and activity, production of a variety of chemokines/cytokines, as well as being cytotoxic in particular conditions. Here, the latest progress in the development of engineered therapeutics and diagnostics inspired by immune cells to ameliorate cancer, inflammatory conditions, autoimmune diseases, neurodegenerative disorders, cardiovascular complications, and infectious diseases is reviewed, and finally, the perspective for their clinical application is delineated.

Immune Cell Membrane-Coated Biomimetic Nanoparticles for Targeted Cancer Therapy

Nanotechnology has provided great opportunities for managing neoplastic conditions at various levels, from preventive and diagnostic to therapeutic fields. However, when it comes to clinical application, nanoparticles (NPs) have some limitations in terms of biological stability, poor targeting, and rapid clearance from the body. Therefore, biomimetic approaches, utilizing immune cell membranes, are proposed to solve these issues. For example, macrophage or neutrophil cell membrane coated NPs are developed with the ability to interact with tumor tissue to suppress cancer progression and metastasis. The functionality of these particles largely depends on the surface proteins of the immune cells and their preserved function during membrane extraction and coating process on the NPs. Proteins on the outer surface of immune cells can render a wide range of activities to the NPs, including prolonged blood circulation, remarkable competency in recognizing antigens for enhanced targeting, better cellular interactions, gradual drug release, and reduced toxicity in vivo. In this review, nano-based systems coated with immune cells-derived membranous layers, their detailed production process, and the applicability of these biomimetic systems in cancer treatment are discussed. In addition, future perspectives and challenges for their clinical translation are also presented.

Emerging vistas in CAR T-cell therapy: challenges and opportunities in solid tumors

INTRODUCTION

Despite advances in modern evidence-based medicine, cancer remains a major cause of global disease-associated mortality. CAR T-cell therapy is a major histocompatibility complex (MHC)-independent immunotherapy involving adoptive cell transfer. Cancer immunotherapy witnessed a major breakthrough with the US FDA approval of the first chimeric antigen receptor (CAR) T-cell therapy Kymriah^TM (tisagenlecleucel) for relapsed or refractory (R/R) acute lymphoblastic leukemia (ALL) in August 2017 followed by approval of Yescarta® (axicabtagene ciloleucel) for R/R non-Hodgkin's lymphoma (NHL) in October 2017.

AREAS COVERED

We review the potential of CAR T-cell therapy which, despite showing great promise in hematological malignancies, faces significant challenges in targeting solid tumors. We address these challenges and discuss proposed strategies to overcome them in solid tumors. We highlight the potential of CAR T-cell therapy as cancer precision medicine and briefly discuss the 'financial toxicity' of CAR T-cell therapy.

EXPERT OPINION

Taken together, we discuss various strategies to circumvent the limitations of CAR T-cell therapy in solid tumors. Despite the rapid advances in CAR NK-cell therapies, there is immense scope for CAR T-cell therapy in solid tumors. We provide a synthetic review of CAR T-cell therapy that will drive future research and harness its full potential in cancer precision medicine for solid tumors.

Innovative CAR-T Cell Therapy for Solid Tumor; Current Duel between CAR-T Spear and Tumor Shield

Novel engineered T cells containing chimeric antigen receptors (CAR-T cells) that combine the benefits of antigen recognition and T cell response have been developed, and their effect in the anti-tumor immunotherapy of patients with relapsed/refractory leukemia has been dramatic. Thus, CAR-T cell immunotherapy is rapidly emerging as a new therapy. However, it has limitations that prevent consistency in therapeutic effects in solid tumors, which accounts for over 90% of all cancer patients. Here, we review the literature regarding various obstacles to CAR-T cell immunotherapy for solid tumors, including those that cause CAR-T cell dysfunction in the immunosuppressive tumor microenvironment, such as reactive oxygen species, pH, O₂, immunosuppressive cells, cytokines, and metabolites, as well as those that impair cell trafficking into the tumor microenvironment. Next-generation CAR-T cell therapy is currently undergoing clinical trials to overcome these challenges. Therefore, novel approaches to address the challenges faced by CAR-T cell immunotherapy in solid tumors are also discussed here.

CAR-T Cell Therapy-An Overview of Targets in Gastric Cancer

Gastric cancer (GC) is one of the most commonly diagnosed malignancies and, unfortunately, still has a high mortality rate. Recent research points to CAR-T immunotherapy as a promising treatment for this disease. Using genetically engineered T cells designed to target a previously selected antigen, researchers are able to harness the natural anti-tumor activity of T cells. For therapy to be successful, however, it is essential to choose antigens that are present on tumor cells but not on healthy cells. In this review, we present an overview of the most important targets for CAR-T therapy in the context of GC, including their biologic function and therapeutic application. A number of clinical studies point to the following as important markers in GC: human epidermal growth factor receptor 2, carcinoembryonic antigen, mucin 1, epithelial cell adhesion molecule, claudin 18.2, mesothelin, natural-killer receptor group 2 member D, and folate receptor 1. Although these markers have been met with some success, the search for new and improved targets continues. Key among these novel biomarkers are the B7H6 ligand, actin-related protein 2/3 (ARP 2/3), neuropilin-1 (NRP-1), desmocollin 2 (DSC2), anion exchanger 1 (AF1), and cancer-related antigens CA-72-4 and CA-19-9.

Cancer immunotherapy through the prism of adaptation: Will Achilles catch the tortoise?

There is no secret that despite the rapid development of new methods of cancer therapy, we still are not able to completely destroy the tumor. Every time we attack the tumor, the tumor neutralizes our attempts. Carcinogenesis can be presented as a tree whose branches are different pro-tumor mechanisms and whose trunk is a biological phenomenon that "feeds" those branches. A tree can be destroyed in two ways: either by cutting a branch for a branch without a guarantee that new branches will not grow, or cutting down the trunk and letting the branches wither away. To cut down the trunk, it is necessary to understand the nature of the biological phenomenon, which helps the tumor to avoid attack by the immune system, drugs and immunotherapy. The clue is that the pro-tumor mechanisms are united by one goal - to increase the resistance of the tumor cell to immune factors and drugs. A phenomenon that improves cell resistance is well known in biology - adaptation. If the immunity does not immediately destroy the tumor cell, the cell begins to adapt to it. Our hypothesis is that short range adaptation to immune factors plays a role in the formation of tumor tolerance for immunity and immunotherapy. This gives rise to the idea of reducing the survival of tumor cells by disrupting adaptation mechanisms. Indeed, "turning off" the immune system for a period of time before therapy and applying immunotherapy only to tumor cells that have lost their increased resistance could be a new approach to increase the effectiveness of immunotherapy.

CAR-T Cell Therapy in Cancer: Tribulations and Road Ahead

Chimeric antigen receptor- (CAR-) T cell therapy is one of the most recent innovative immunotherapies and is rapidly evolving. Like other technologies, CAR-T cell therapy has undergone a long development process, and persistent explorations of the actions of the intracellular signaling domain and make several improvements have led to the superior efficacy when anti-CD19 CAR-T cell treatments in B cell cancers. At present, CAR-T cell therapy is developing rapidly, and many clinical trials have been established on a global scale, which has great commercial potential. This review mainly describes the toxicity of CAR-T cell therapy and the challenges of CAR-T cells in the treatment of solid tumors, and looks forward to future development and opportunities for immunotherapy and reviews major breakthroughs in CAR-T cell therapy.

Finding the Keys to the CAR: Identifying Novel Target Antigens for T Cell Redirection Immunotherapies

Oncology immunotherapy has been a significant advancement in cancer treatment and involves harnessing and redirecting a patient’s immune response towards their own tumour. Specific recognition and elimination of tumour cells was first proposed over a century ago with Paul Erlich’s ‘magic bullet’ theory of therapy. In the past decades, targeting cancer antigens by redirecting T cells with antibodies using either bispecific T cell engagers (BiTEs) or chimeric antigen receptor (CAR) T cell therapy has achieved impressive clinical responses. Despite recent successes in haematological cancers, linked to a high and uniformly expressed CD19 antigen, the efficacy of T cell therapies in solid cancers has been disappointing, in part due to antigen escape. Targeting heterogeneous solid tumours with T cell therapies will require the identification of novel tumour specific targets. These targets can be found among a range of cell-surface expressed antigens, including proteins, glycolipids or carbohydrates. In this review, we will introduce the current tumour target antigen classification, outline existing approaches to discover novel tumour target antigens and discuss considerations for future design of antibodies with a focus on their use in CAR T cells.

Proposing a tandem AND-gate CAR T cell targeting glioblastoma multiforme

CAR T cell therapy is suggested as an effective method to treat hematological malignancies. However, high recurrence rates and in vivo toxicities have limited their widespread use. In order to reduce toxicity and improve tumor specificity, we propose a CAR T cell targeting glioblastoma multiforme utilizing the synNotch receptor pathway linked to a tandem CAR T cell. The extracellular domain of the synNotch receptor is replaced by a single chain fragment variable specific for the EGF receptor variant III (scfv-EGFRvIII), and covalently bonded to a IL-13Rα2-CD133-tandem CAR. This would produce an AND-gate CAR-T cell, which requires activation of both signals from synNotch receptor binding to EGFRvIII and then binding of the tandem CAR to either of the two IL-13Rα2 or CD133 ligands-specific antigens for glioblastoma stem cells. SynNotch receptor activation along with the 4-1BB costimulatory domain results in CAR T cell expression under the TRE promoter, culminating in a tri-specific and effective tumor stem cell recognition and elimination of glioblastoma multiforme.

Chimeric Antigen Receptors for the Tumour Microenvironment

Chimeric antigen receptor T (CAR-T) cell therapy has dramatically revolutionised cancer treatment. The FDA approval of two CAR-T cell products for otherwise incurable refractory B-cell acute lymphoblastic leukaemia (B-ALL) and aggressive B-cell non-Hodgkin lymphoma has established this treatment as an effective immunotherapy option. The race for extending CAR-T therapy for various tumours is well and truly underway. However, response rates in solid organ cancers have been inadequate thus far, partly due to challenges posed by the tumour microenvironment (TME). The TME is a complex structure whose role is to subserve the persistence and proliferation of tumours as well as support their escape from immune surveillance. It presents several obstacles like inhibitory immune checkpoint proteins, immunosuppressive cells, cytokines, chemokines, stromal factors and adverse metabolic pathways. CAR structure and CAR-T therapies have evolved to overcome these obstacles, and we now have several novel CARs with improved anti-tumour activity demonstrated in xenograft models and in some clinical trials. This chapter provides a discussion of the evolution of CAR-T therapies to enable targeting specific aspects of the TME.

Mitochondria-Targeting Immunogenic Cell Death Inducer Improves the Adoptive T-Cell Therapy Against Solid Tumor

Cancer immunotherapy including adoptive T cell therapy (ACT) is widely used in the clinic and is highly beneficial for patients with hematological malignancies; however, it remains a challenge to develop effective immunotherapy strategies for the treatment of solid cancers, due to the inefficiency of the immune response and the immunosuppressive tumor microenvironment (TME). Immunogenic cell death (ICD) converts dying cancer cells into a therapeutic vaccine and stimulate a systemic antigen-specific antitumor immune response, which can effectively subvert the immunosuppressive TME and enhance the efficiency of immune responses, relative to conventional immunotherapeutic regimens. However, the application of traditional inducers of ICD in anti-cancer immunotherapy has been limited because of low levels of ICD induction and a lack of tumor-targeting accumulation. Mitochondria are important for tumor-targeting strategies and have emerged as organelles with key roles in the immune system. We hypothesized that the alteration of mitochondria in cancer cells could be an important target for the development of an efficient ICD inducer for use in cancer immunotherapy. Here, we report the evaluation of a mitochondria-targeted small molecule, IR-780, that acts as an ICD inducer and exhibits exceptional antineoplastic activity. IR-780 specifically accumulated in tumor cells to elicit ICD in vitro and in vivo, effectively suppressed tumor growth and lung metastasis, and enhanced adoptive T-cell therapy effects against solid tumors in mouse models. These anticancer effects were linked to dendritic cell maturation and synergistic effector T cell priming and infiltration into tumors. The underlying mechanism involves the direct targeting of the mitochondria by IR-780, to destroy cancer cells, including drug-resistant cancer cells, leading to the full exposure of tumor-associated antigens (TAAs), thereby enhancing antigen-specific antitumor immune responses. These features of IR-780 suggest that it has the advantage of leading to complete TAA exposure and the stimulation of efficient antitumor immune responses in the TME. IR-780 has potential for use as a preparative ICD inducer, in combination with conventional immunostimulatory regimens for cancer immunotherapy, particularly in the context of solid tumor treatment.

Retargeting CD19 Chimeric Antigen Receptor T Cells via Engineered CD19-Fusion Proteins

CD19-targeted chimeric antigen receptor (CAR) T-cells (CAR19s) show remarkable efficacy in the treatment of relapsed/refractory acute lymphocytic leukemia and Non-Hodgkin's lymphoma. However, the use of CAR T-cell therapy against CD19-negative hematological cancers and solid tumors has been challenging. We propose CD19-fusion proteins (CD19-FPs) to leverage the benefits of CAR19s while retargeting this validated cellular therapy to alternative tumor antigens. We demonstrate the ability of a fusion of CD19 extracellular domain (ECD) and a human epidermal growth factor receptor 2 (HER2) single-chain antibody fragment to retarget CAR19s to kill HER2⁺ CD19^- tumor cells. To enhance the modularity of this technology, we engineered a more robust CD19 ECD via deep mutational scanning with yeast display and flow cytometric selections for improved protease resistance and anti-CD19 antibody binding. These enhanced CD19 ECDs significantly increase, and in some cases recover, fusion protein expression while maintaining target antigen affinity. Importantly, CD19-FPs retarget CAR19s to kill tumor cells expressing multiple distinct antigens, including HER2, CD20, EGFR, BCMA, and Clec12A as N- or C-terminal fusions and linked to both antibody fragments and fibronectin ligands. This study provides fundamental insights into CD19 sequence-function relationships and defines a flexible and modular platform to retarget CAR19s to any tumor antigen.

Management of neoplastic pericardial disease

At present, there is no accurate and effective method for treating neoplastic pericardial effusion. This study analyzed the current literature on the treatment of neoplastic pericardial effusion to provide advice and guidance for clinical treatment. Surgical treatments include pericardial puncture, extension of catheter drainage, pericardial window, and surgical pericardiotomy. Each surgical procedure has a corresponding indication, and the best treatment is selected according to the patient's specific conditions. Systemic chemotherapy is effective in lymphoma and small cell lung cancer that are sensitive to chemotherapeutic drugs. Although pericardial injection of drugs is effective for pericardial tamponade and recurrent pericardial effusion, these methods can only temporarily relieve symptoms and cannot prolong the life of patients. In recent years, immunotherapy, especially adoptive immunotherapy, has achieved good results in the treatment of neoplastic pericardial effusion, thus providing a novel treatment option for neoplastic pericardial effusion.

CARs of the future

CAR T cells have revolutionized the treatment of relapsed and refractory CD19-positive leukemia and lymphoma. Unfortunately, the majority of patients treated will not achieve durable remissions. Reasons for these suboptimal clinical outcomes can be tied back to intrinsic CAR T cell design and manufacturing processes, factors that are highly amenable to modification and improvement. As CAR T cell therapy is being deployed in spaces outside of CD19-positive disease, these limitations, complications, and setbacks need to be overcome, allowing for the full potential of this novel therapy to be realized. Preclinical work has begun tackling these major roadblocks, paving the way for potentially off-the-shelf products that are safer and more potent. In time, a number of these advances will be translated to the clinic and usher in an era of CARs of the future.