CARs: Synthetic Immunoreceptors for Cancer Therapy and Beyond

Advances in CAR T Cell Therapy for Non-Small Cell Lung Cancer

Since its first approval by the FDA in 2017, tremendous progress has been made in chimeric antigen receptor (CAR) T cell therapy, the adoptive transfer of engineered, CAR-expressing T lymphocyte. CAR T cells are all composed of three main elements: an extracellular antigen-binding domain, an intracellular signaling domain responsible for T cell activation, and a hinge that joins these two domains. Continuous improvement has been made in CARs, now in their fifth generation, particularly in the intracellular signaling domain responsible for T cell activation. CAR T cell therapy has revolutionized the treatment of hematologic malignancies. Nonetheless, the use of CAR T cell therapy for solid tumors has not attained comparable levels of success. Here we review the challenges in achieving effective CAR T cell therapy in solid tumors, and emerging CAR T cells that have shown great promise for non-small cell lung cancer (NSCLC). A growing number of clinical trials have been conducted to study the effect of CAR T cell therapy on NSCLC, targeting different types of surface antigens. They include epidermal growth factor receptor (EGFR), mesothelin (MSLN), prostate stem cell antigen (PSCA), and mucin 1 (MUC1). Potential new targets such as erythropoietin-producing hepatocellular carcinoma A2 (EphA2), tissue factor (TF), and protein tyrosine kinase 7 (PTK7) are currently under investigation in clinical trials. The challenges in developing CAR T for NSCLC therapy and other approaches for enhancing CAR T efficacy are discussed. Finally, we provide our perspective on imaging CAR T cell action by reviewing the two main radionuclide-based CAR T cell imaging techniques, the direct labeling of CAR T cells or indirect labeling via a reporter gene.

Successes and challenges in clinical gene therapy

Despite the ups and downs in the field over three decades, the science of gene therapy has continued to advance and provide enduring treatments for increasing number of diseases. There are active clinical trials approaching a variety of inherited and acquired disorders of different organ systems. Approaches include ex vivo modification of hematologic stem cells (HSC), T lymphocytes and other immune cells, as well as in vivo delivery of genes or gene editing reagents to the relevant target cells by either local or systemic administration. In this article, we highlight success and ongoing challenges in three areas of high activity in gene therapy: inherited blood cell diseases by targeting hematopoietic stem cells, malignant disorders using immune effector cells genetically modified with chimeric antigen receptors, and ophthalmologic, neurologic, and coagulation disorders using in vivo administration of adeno-associated virus (AAV) vectors. In recent years, there have been true cures for many of these diseases, with sustained clinical benefit that exceed those from other medical approaches. Each of these treatments faces ongoing challenges, namely their high one-time costs and the complexity of manufacturing the therapeutic agents, which are biological viruses and cell products, at pharmacologic standards of quality and consistency. New models of reimbursement are needed to make these innovative treatments widely available to patients in need.

Effects of polybrene and retronectin as transduction enhancers on the development and phenotypic characteristics of VHH-based CD19-redirected CAR T cells: a comparative investigation

Chimeric antigen receptor T cells (CAR T cells) have improved the prognosis of patients with certain hematologic malignancies. However, broader clinical application of this type of therapy is dependent on production protocols. We characterized VHH-based CD19-redirected CAR T cells generated using the transduction enhancers (TEs) polybrene or retronectin. The proliferation rate of activated T cells transduced using polybrene concentrations > 6 mg/mL decreased compared with untreated group. There was a direct relationship between polybrene concentration and transduction efficacy. Moreover, we demonstrated the proliferation of retronectin-transduced T cells increased in a dose-dependent manner (4-20 μg/mL). Whereas, different retronectin concentrations did not mediate a significant increase in T cell transduction rate. Moreover, lentiviral transduction rate was also dependent on the concentration of lentiviruses. At optimized TE concentrations, multiplicity of infection (MOI) of > 10 decreased living T cell transduction rate. Additionally, we demonstrated that CAR T cell phenotype is highly affected by TE type. Naïve T cell differentiation to central memory T cell was observed in the beginning of the expansion process and effector memory T cells became the predominant subset in the second week of expansion. Importantly, retronectin increased the proliferation of CAR T cells alongside medicating higher transduction rates, resulting in more naïve and central memory T cells. We demonstrated that a higher percentage of CAR T cells were generated using retronectin (with a less differentiated phenotype) making retronectin a more effective TE than polybrene for long-term CAR T cell processing in preclinical or clinical studies.

Breaking down barriers: The potential of smarter CAR-engineered NK cells against solid tumors

Natural killer (NK) cells are considered to be the foremost fighters of our innate immune system against foreign invaders and thus tend to promptly latch onto the virus-infected and tumor/cancerous cells, killing them through phagocytosis. At present, the application of genetically engineered Chimeric antigen receptor (CAR) receptors ensures a guaranteed optimistic response with NK cells and would not allow the affected cells to dodge or escape unchecked. Hence the specificity and uniqueness of CAR-NK cells over CAR-T therapy make them a better immunotherapeutic choice to reduce the load of trafficking of numerous tumor cells near the healthy cell populations in a more intact way than offered by CAR-T immunotherapy. Our review mainly focuses on the preclinical, clinical, and recent advances in clinical research trials and further strategies to achieve an augmented and efficient cure against solid tumors.

Harnessing the potential of CAR-T cell therapy: progress, challenges, and future directions in hematological and solid tumor treatments

Traditional cancer treatments use nonspecific drugs and monoclonal antibodies to target tumor cells. Chimeric antigen receptor (CAR)-T cell therapy, however, leverages the immune system's T-cells to recognize and attack tumor cells. T-cells are isolated from patients and modified to target tumor-associated antigens. CAR-T therapy has achieved FDA approval for treating blood cancers like B-cell acute lymphoblastic leukemia, large B-cell lymphoma, and multiple myeloma by targeting CD-19 and B-cell maturation antigens. Bi-specific chimeric antigen receptors may contribute to mitigating tumor antigen escape, but their efficacy could be limited in cases where certain tumor cells do not express the targeted antigens. Despite success in blood cancers, CAR-T technology faces challenges in solid tumors, including lack of reliable tumor-associated antigens, hypoxic cores, immunosuppressive tumor environments, enhanced reactive oxygen species, and decreased T-cell infiltration. To overcome these challenges, current research aims to identify reliable tumor-associated antigens and develop cost-effective, tumor microenvironment-specific CAR-T cells. This review covers the evolution of CAR-T therapy against various tumors, including hematological and solid tumors, highlights challenges faced by CAR-T cell therapy, and suggests strategies to overcome these obstacles, such as utilizing single-cell RNA sequencing and artificial intelligence to optimize clinical-grade CAR-T cells.

Neurological adverse effects of chimeric antigen receptor T-cell therapy

INTRODUCTION

Chimeric antigen receptor (CAR) T-cell is among the most prevalent approaches that act by directing T-cells toward cancer; however, they need to be optimized to minimize side effects and maximize efficacy before being used as standard treatment for malignancies. Neurotoxicity associated with CAR T-cell therapy has been well-documented in recent works.

AREAS COVERED

In this regard, two established syndromes exist. Immune effector cell-associated neurotoxicity syndrome (ICANS), previously called cytokine release encephalopathy syndrome (CRES), is a neuropsychiatric condition which can occur after therapy by immune effector cells (IEC) and T-lymphocytes utilizing treatments. Another syndrome is cytokine release syndrome (CRS), which may overlap with ICANS.

EXPERT OPINION

ICANS clinical manifestations include cerebral edema, mild lethargy, aphasia, and seizures. Notably, ICANS is associated with changes to EEG and neuroradiological findings. Therefore, it is necessary to make a timely and accurate diagnosis of neurological complications of CAR T-cells by clinical presentations, neuroimaging, and EEG. Since neurological events by different CAR T-cell products are heterogeneous, guides should be developed according to each product. Here, we provide an updated review of general information on CAR T-cell therapies and applications, neurological syndromes associated with their use, and risk factors contributing to ICANS.

Development of CD30 CAR-T cells in refractory or relapsed Hodgkin's lymphoma

INTRODUCTION

After therapy, approximately 15% of individuals with Hodgkin's lymphoma (HL) develop relapsed or drug-resistant Hodgkin's lymphoma (r/rHL). r/rHL has a high fatality rate and poor therapeutic prognosis. CD30 CAR-T-cell therapy has emerged as a new way to treat r/rHL in recent years. However, CD30CAR-T cells are still being explored in clinical trials. To help more patients, this review focuses on current CD30CAR-T-cell advancements as well as clinical breakthroughs in treatment of r/rHL.

AREAS COVERED

This research examines the mechanism of action of CD30 CAR-T cells, their function in the real-world therapy of r/rHL, and the influence of different treatment regimens on treatment results.

EXPERT OPINION

There has been much research into CD30 CAR-T cells as a result of their successful use in treatment of r/rHL. This research has helped us to understand CD30 CAR-T-cell safety as well as the management options available before and after its administration to increase patient survival and reduce side effects.

Exploring the Role of Enhancer-Mediated Transcriptional Regulation in Precision Biology

The emergence of precision biology has been driven by the development of advanced technologies and techniques in high-resolution biological research systems. Enhancer-mediated transcriptional regulation, a complex network of gene expression and regulation in eukaryotes, has attracted significant attention as a promising avenue for investigating the underlying mechanisms of biological processes and diseases. To address biological problems with precision, large amounts of data, functional information, and research on the mechanisms of action of biological molecules is required to address biological problems with precision. Enhancers, including typical enhancers and super enhancers, play a crucial role in gene expression and regulation within this network. The identification and targeting of disease-associated enhancers hold the potential to advance precision medicine. In this review, we present the concepts, progress, importance, and challenges in precision biology, transcription regulation, and enhancers. Furthermore, we propose a model of transcriptional regulation for multi-enhancers and provide examples of their mechanisms in mammalian cells, thereby enhancing our understanding of how enhancers achieve precise regulation of gene expression in life processes. Precision biology holds promise in providing new tools and platforms for discovering insights into gene expression and disease occurrence, ultimately benefiting individuals and society as a whole.

CAR T Cell Therapy: A Versatile Living Drug

After seeing a dramatic increase in the development and use of immunotherapy and precision medicine over the past few decades, oncological care now embraces the start of the adoptive cell therapy (ACT) era. This impulse towards a new treatment paradigm has been led by chimeric antigen receptor (CAR) T cells, the only type of ACT medicinal product to be commercialized so far. Brought about by an ever-growing understanding of cellular engineering, CAR T cells are T lymphocytes genetically modified with an appropriate DNA construct, which endows them with expression of a CAR, a fusion protein between a ligand-specific recognition domain, often an antibody-like structure, and the activating signaling domain of the T cell receptor. Through this genetic enhancement, CAR T cells are engineered from a cancer patient’s own lymphocytes to better target and kill their cancer cells, and the current amassed data on clinical outcomes point to a stream of bright developments in the near future. Herein, from concept design and present-day manufacturing techniques to pressing hurdles and bright discoveries around the corner, we review and thoroughly describe the state of the art in CAR T cell therapy.

Structure and mechanism of immunoreceptors: New horizons in T cell and B cell receptor biology and beyond

Immunoreceptors, also named non-catalytic tyrosine-phosphorylated receptors, are a large class of leukocyte cell-surface proteins critically involved in innate and adaptive immune responses. Their most characteristic defining feature is a shared signal transduction machinery where binding events of cell surface-anchored ligands to the small extracellular receptor domains are translated into phosphorylation of conserved tyrosine-containing cytosolic sequence motifs initiating downstream signal transduction cascades. Despite their central importance to immunology, the molecular mechanism of how ligand binding activates the receptors and results in robust intracellular signaling has remained enigmatic. Recent breakthroughs in our understanding of the architecture and triggering mechanism of immunoreceptors come from cryogenic electron microscopy studies of the B cell and T cell antigen receptors.

Touch-free optical technologies to streamline the production of T cell therapies

Currently approved adoptive T cell therapy relies on autologous (obtained from the same patient) T cells, which often suffer from poor quality that diminishes treatment efficacy. Due to the heterogeneous nature of T cell quality between and within patients, significant efforts are aimed at optimizing cell manipulation and growth conditions for potent T cell products. We believe that touch-free imaging and sensing technologies are critical to monitor single-cell features during T cell manufacturing to ensure consistent and optimally timed methods for cell manipulation and growth. Here, we discuss emerging label-free optical imaging and sensing methods, along with machine learning techniques that could enable in-line feedback to optimize T cell quality at multiple stages during manufacturing. These methods have the potential to streamline current workflow, accelerate the manufacture of safe high-quality T cell therapies, and improve our understanding of the dynamic, heterogeneous processes of T cell manufacturing.

CAR-T Cells with Phytohemagglutinin (PHA) Provide Anti-Cancer Capacity with Better Proliferation, Rejuvenated Effector Memory, and Reduced Exhausted T Cell Frequencies

The development of genetic modification techniques has led to a new era in cancer treatments that have been limited to conventional treatments such as chemotherapy. intensive efforts are being performed to develop cancer-targeted therapies to avoid the elimination of non-cancerous cells. One of the most promising approaches is genetically modified CAR-T cell therapy. The high central memory T cell (Tcm) and stem cell-like memory T cell (Tscm) ratios in the CAR-T cell population increase the effectiveness of immunotherapy. Therefore, it is important to increase the populations of CAR-expressing Tcm and Tscm cells to ensure that CAR-T cells remain long-term and have cytotoxic (anti-tumor) efficacy. In this study, we aimed to improve CAR-T cell therapy's time-dependent efficacy and stability, increasing the survival time and reducing the probability of cancer cell growth. To increase the sub-population of Tcm and Tscm in CAR-T cells, we investigated the production of a long-term stable and efficient cytotoxic CAR-T cell by modifications in the cell activation-dependent production using Phytohemagglutinin (PHA). PHA, a lectin that binds to the membranes of T cells and increases metabolic activity and cell division, is studied to increase the Tcm and Tscm population. Although it is known that PHA significantly increases Tcm cells, B-lymphocyte antigen CD19-specific CAR-T cell expansion, its anti-cancer and memory capacity has not yet been tested compared with aCD3/aCD28-amplified CAR-T cells. Two different types of CARs (aCD19 scFv CD8-(CD28 or 4-1BB)-CD3z-EGFRt)-expressing T cells were generated and their immunogenic phenotype, exhausted phenotype, Tcm-Tscm populations, and cytotoxic activities were determined in this study. The proportion of T cell memory phenotype in the CAR-T cell populations generated by PHA was observed to be higher than that of aCD3/aCD28-amplified CAR-T cells with similar and higher proliferation capacity. Here, we show that PHA provides long-term and efficient CAR-T cell production, suggesting a potential alternative to aCD3/aCD28-amplified CAR-T cells.

Interleukin Inhibitors in Cytokine Release Syndrome and Neurotoxicity Secondary to CAR-T Therapy

Introduction: Chimeric antigen receptor T-cell (CAR-T) therapy is an innovative therapeutic option for addressing certain recurrent or refractory hematological malignancies. However, CAR-T cells also cause the release of pro-inflammatory cytokines that lead to life-threatening cytokine release syndrome and neurotoxicity. Objective: To study the efficacy of interleukin inhibitors in addressing cytokine release syndrome (CRS) and neurotoxicity secondary to CAR-T therapy. Methodology: The authors conducted a bibliographic review in which 10 articles were analyzed. These included cut-off studies, case reports, and clinical trials involving 11 cancer centers and up to 475 patients over 18 years of age. Results: Tocilizumab is the only interleukin inhibitor approved to address CRS secondary to CAR-T therapy due to its efficacy and safety. Other inhibitors, such as siltuximab and anakinra, could be useful in combination with tocilizumab for preventing severe cytokine release and neurotoxicity. In addition, the new specific inhibitors could be effective in mitigating CRS without affecting the cytotoxic efficacy of CAR-T therapy. Conclusion: More lines of research should be opened to elucidate the true implications of these drugs in treating the side effects of CAR-T therapy.

Immune effector cell-associated neurotoxicity syndrome: A therapeutic approach in the critically ill

Immunotherapy with chimeric antigen-specific receptor modified T cells, known as CAR-T, is emerging as a promising approach to hematological malignancies. In this regard, CAR-T against human cluster of differentiation (CD) 19 has demonstrated antitumor efficacy in application to B cell neoplasms resistant to conventional therapy. However, activation of the immune system induces severe and specific complications which can prove life-threatening. These include cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome (known as ICANS) - the latter being the subject of the present review. Although the physiopathological mechanisms underlying ICANS are not well known, a number of clinical and biological factors increase the risk of developing neurotoxicity associated to CAR-T therapy. Treatment is based on close monitoring, measures of support, anticonvulsivants, corticosteroids, and early admission to intensive care. The present study offers a comprehensive review of the available literature from a multidisciplinary perspective, including recommendations from intensivists, neurologists and hematologists dedicated to the care of critically ill adults.

The Promise of CAR T-Cell Therapy for the treatment of cancer stem cells: A Short Review

Chimeric antigen receptor (CAR) T-cell therapy is a type of sophisticated tailored immunotherapy used to treat a variety of tumors. Immunotherapy works by utilizing the body's own immune system to discover and destroy malignant cells. In CAR-T therapy, a patient's own immune cells are genetically engineered to recognize and attack cancer. Treatments employing CAR T-cells are currently showing promising therapeutic results in patients with hematologic malignancies, and their safety and feasibility in solid tumors has been verified. In this review, we will discuss in detail the likelihood that CAR T-cells inhibit cancer stem cells (CSCs) by selectively targeting their cell surface markers will ultimately improve the therapeutic response for patients with various forms of cancer. This review addresses the major components of cancer stem cell (CSC)-targeted CAR T-cells against malignancies, from bench to bedside.

Engineering a natural ligand-based CAR: directed evolution of the stress-receptor NKp30

B7H6, a stress-induced ligand which binds to the NK cell receptor NKp30, has recently emerged as a promising candidate for immunotherapy due to its tumor-specific expression on a broad array of human tumors. NKp30 can function as a chimeric antigen receptor (CAR) extracellular domain but exhibits weak binding with a fast on and off rate to B7H6 compared to the TZ47 anti-B7H6 single-chain variable fragment (scFv). Here, directed evolution using yeast display was employed to isolate novel NKp30 variants that bind to B7H6 with higher affinity compared to the native receptor but retain its fast association and dissociation profile. Two variants, CC3 and CC5, were selected for further characterization and were expressed as soluble Fc-fusion proteins and CARs containing CD28 and CD3ς intracellular domains. We observed that Fc-fusion protein forms of NKp30 and its variants were better able to bind tumor cells expressing low levels of B7H6 than TZ47, and that the novel variants generally exhibited improved in vitro tumor cell killing relative to NKp30. Interestingly, CAR T cells expressing the engineered variants produced unique cytokine signatures in response to multiple tumor types expressing B7H6 compared to both NKp30 and TZ47. These findings suggest that natural CAR receptors can be fine-tuned to produce more desirable signaling outputs while maintaining evolutionary advantages in ligand recognition relative to scFvs.

Brain capillary obstruction during neurotoxicity in a mouse model of anti-CD19 chimeric antigen receptor T-cell therapy

Immunotherapy for haematologic malignancies with CD19-directed chimeric antigen receptor T cells has been highly successful at eradicating cancer but is associated with acute neurotoxicity in ∼40% of patients. This neurotoxicity correlates with systemic cytokine release syndrome, endothelial activation and disruption of endothelial integrity, but it remains unclear how these mechanisms interact and how they lead to neurologic dysfunction. We hypothesized that dysfunction of the neurovascular unit is a key step in the development of neurotoxicity. To recapitulate the interaction of the intact immune system with the blood-brain barrier, we first developed an immunocompetent mouse model of chimeric antigen receptor T-cell treatment-associated neurotoxicity. We treated wild-type mice with cyclophosphamide lymphodepletion followed by escalating doses of murine CD19-directed chimeric antigen receptor T cells. Within 3-5 days after chimeric antigen receptor T-cell infusion, these mice developed systemic cytokine release and abnormal behaviour as measured by daily neurologic screening exams and open-field testing. Histologic examination revealed widespread brain haemorrhages, diffuse extravascular immunoglobulin deposition, loss of capillary pericyte coverage and increased prevalence of string capillaries. To measure any associated changes in cerebral microvascular blood flow, we performed in vivo two-photon imaging through thinned-skull cranial windows. Unexpectedly, we found that 11.9% of cortical capillaries were plugged by Day 6 after chimeric antigen receptor T-cell treatment, compared to 1.1% in controls treated with mock transduced T cells. The capillary plugs comprised CD45+ leucocytes, a subset of which were CD3+ T cells. Plugging of this severity is expected to compromise cerebral perfusion. Indeed, we found widely distributed patchy hypoxia by hypoxyprobe immunolabelling. Increased serum levels of soluble ICAM-1 and VCAM-1 support a putative mechanism of increased leucocyte-endothelial adhesion. These data reveal that brain capillary obstruction may cause sufficient microvascular compromise to explain the clinical phenotype of chimeric antigen receptor T-cell neurotoxicity. The translational impact of this finding is strengthened by the fact that our mouse model closely approximates the kinetics and histologic findings of the chimeric antigen receptor T-cell neurotoxicity syndrome seen in human patients. This new link between systemic immune activation and neurovascular unit injury may be amenable to therapeutic intervention.

Design and development of engineered receptors for cell and tissue engineering

Advances in synthetic biology have provided genetic tools to reprogram cells to obtain desired cellular functions that include tools to enable the customization of cells to sense an extracellular signal and respond with a desired output. These include a variety of engineered receptors capable of transmembrane signaling that transmit information from outside of the cell to inside when specific ligands bind to them. Recent advances in synthetic receptor engineering have enabled the reprogramming of cell and tissue behavior, controlling cell fate decisions, and providing new vehicles for therapeutic delivery.

Engineering living therapeutics with synthetic biology

The steadfast advance of the synthetic biology field has enabled scientists to use genetically engineered cells, instead of small molecules or biologics, as the basis for the development of novel therapeutics. Cells endowed with synthetic gene circuits can control the localization, timing and dosage of therapeutic activities in response to specific disease biomarkers and thus represent a powerful new weapon in the fight against disease. Here, we conceptualize how synthetic biology approaches can be applied to programme living cells with therapeutic functions and discuss the advantages that they offer over conventional therapies in terms of flexibility, specificity and predictability, as well as challenges for their development. We present notable advances in the creation of engineered cells that harbour synthetic gene circuits capable of biological sensing and computation of signals derived from intracellular or extracellular biomarkers. We categorize and describe these developments based on the cell scaffold (human or microbial) and the site at which the engineered cell exerts its therapeutic function within its human host. The design of cell-based therapeutics with synthetic biology is a rapidly growing strategy in medicine that holds great promise for the development of effective treatments for a wide variety of human diseases.

Potent, Selective CARs as Potential T-Cell Therapeutics for HPV-positive Cancers

Next-generation T-cell therapies will likely continue to utilize T-cell receptors (TCRs) and chimeric antigen receptors (CARs) because each receptor type has advantages. TCRs often possess exceptional properties even when tested unmodified from patients' T cells. CARs are generally less sensitive, possibly because their ligand-binding domains are grafted from antibodies selected for binding affinity or avidity and not broadly optimized for a functional response. Because of the disconnect between binding and function among these receptor types, the ultimate potential of CARs optimized for sensitivity and selectivity is not clear. Here, we focus on a thoroughly studied immuno-oncology target, the HLA-A*02/HPV-E629-38 complex, and show that CARs can be optimized by a combination of high-throughput binding screens and low-throughput functional assays to have comparable activity to clinical TCRs in acute assays in vitro. These results provide a case study for the challenges and opportunities of optimizing high-performing CARs, especially in the context of targets utilized naturally by TCRs.

Thrombopoietin-based CAR-T cells demonstrate in vitro and in vivo cytotoxicity to MPL positive acute myelogenous leukemia and hematopoietic stem cells

While targeting CD19+ hematologic malignancies with CAR T cell therapy using single chain variable fragments (scFv) has been highly successful, novel strategies for applying CAR T cell therapy with other tumor types are necessary. In the current study, CAR T cells were designed using a ligand binding domain instead of an scFv to target stem-like leukemia cells. Thrombopoietin (TPO), the natural ligand to the myeloproliferative leukemia protein (MPL) receptor, was used as the antigen binding domain to engage MPL expressed on hematopoietic stem cells (HSC) and erythropoietic and megakaryocytic acute myeloid leukemias (AML). TPO-CAR T cells were tested in vitro against AML cell lines with varied MPL expression to test specificity. TPO-CAR T cells were specifically activating and cytotoxic against MPL+ leukemia cell lines. Though the TPO-CAR T cells did not extend survival in vivo, it successfully cleared the MPL+ fraction of leukemia cells. As expected, we also show the TPO-CAR is cytotoxic against MPL expressing bone marrow compartment in AML xenograft models. The data collected demonstrate preclinical potential of TPO-CAR T cells for stem-like leukemia through assessment of targeted killing of MPL+ cells and may facilitate subsequent HSC transplant under reduced intensity conditioning regimens.

Single Molecule Force Spectroscopy Reveals Distinctions in Key Biophysical Parameters of αβ T-Cell Receptors Compared with Chimeric Antigen Receptors Directed at the Same Ligand

Chimeric antigen receptor (CAR) T-cell therapies exploit facile antibody-mediated targeting to elicit useful immune responses in patients. This work directly compares binding profiles of CAR and αβ T-cell receptors (TCR) with single cell and single molecule optical trap measurements against a shared ligand. DNA-tethered measurements of peptide-major histocompatibility complex (pMHC) ligand interaction in both CAR and TCR exhibit catch bonds with specific peptide agonist peaking at 25 and 14 pN, respectively. While a conformational transition is regularly seen in TCR-pMHC systems, that of CAR-pMHC systems is dissimilar, being infrequent, of lower magnitude, and irreversible. Slip bonds are observed with CD19-specific CAR T-cells and with a monoclonal antibody mapping to the MHC α2 helix but indifferent to the bound peptide. Collectively, these findings suggest that the CAR-pMHC interface underpins the CAR catch bond response to pMHC ligands in contradistinction to slip bonds for CARs targeting canonical ligands.

Engineered red blood cells as an off-the-shelf allogeneic anti-tumor therapeutic

Checkpoint inhibitors and T-cell therapies have highlighted the critical role of T cells in anti-cancer immunity. However, limitations associated with these treatments drive the need for alternative approaches. Here, we engineer red blood cells into artificial antigen-presenting cells (aAPCs) presenting a peptide bound to the major histocompatibility complex I, the costimulatory ligand 4-1BBL, and interleukin (IL)-12. This leads to robust, antigen-specific T-cell expansion, memory formation, additional immune activation, tumor control, and antigen spreading in tumor models in vivo. The presence of 4-1BBL and IL-12 induces minimal toxicities due to restriction to the vasculature and spleen. The allogeneic aAPC, RTX-321, comprised of human leukocyte antigen-A*02:01 presenting the human papilloma virus (HPV) peptide HPV16 E7_11-19, 4-1BBL, and IL-12 on the surface, activates HPV-specific T cells and promotes effector function in vitro. Thus, RTX-321 is a potential 'off-the-shelf' in vivo cellular immunotherapy for treating HPV + cancers, including cervical and head/neck cancers.

Cell therapy in transplantation: A comprehensive review of the current applications of cell therapy in transplant patients with the focus on Tregs, CAR Tregs, and Mesenchymal stem cells

Organ transplantation is a practical treatment for patients with end-stage organ failure. Despite the advances in short-term graft survival, long-term graft survival remains the main challenge considering the increased mortality and morbidity associated with chronic rejection and the toxicity of immunosuppressive drugs. Since a novel therapeutic strategy to induce allograft tolerance seems urgent, focusing on developing novel and safe approaches to prolong graft survival is one of the main goals of transplant investigators. Researchers in the field of organ transplantation are interested in suppressing or optimizing the immune responses by focusing on immune cells including mesenchymal stem cells (MSCs), polyclonal regulatory Tcells (Tregs), and antigen-specific Tregs engineered with chimeric antigen receptors (CAR Tregs). We review the mechanistic pathways, phenotypic and functional characteristics of these cells, and their promising application in organ transplantation.

Cancer Immunology and CAR-T Cells: A Turning Point Therapeutic Approach in Colorectal Carcinoma with Clinical Insight

Cancer immunotherapy endeavours in harnessing the delicate strength and specificity of the immune system for therapy of different malignancies, including colorectal carcinoma. The recent challenge for cancer immunotherapy is to practice and develop molecular immunology tools to create tactics that efficiently and securely boost antitumor reactions. After several attempts of deceptive outcomes, the wave has lastly altered and immunotherapy has become a clinically confirmed treatment for several cancers. Immunotherapeutic methods include the administration of antibodies or modified proteins that either block cellular activity or co-stimulate cells through immune control pathways, cancer vaccines, oncolytic bacteria, ex vivo activated adoptive transfer of T cells and natural killer cells. Engineered T cells are used to produce a chimeric antigen receptor (CAR) to treat different malignancies, including colorectal carcinoma in a recent decade. Despite the considerable early clinical success, CAR-T therapies are associated with some side effects and sometimes display minimal efficacy. It gives special emphasis on the latest clinical evidence with CAR-T technology and also other related immunotherapeutic methods with promising performance, and highlighted how this therapy can affect the therapeutic outcome and next upsurge as a key clinical aspect of colorectal carcinoma. In this review, we recapitulate the current developments produced to improve the efficacy and specificity of CAR-T therapies in colon cancer.

Chimeric antigen receptor-engineered natural killer cells: a promising cancer immunotherapy

Introduction:Widespread success of CD19 chimeric antigen receptor (CAR) T cells for the treatment of hematological malignancies have shifted the focus from conventional cancer treatments toward adoptive immunotherapy. There are major efforts to improve CAR constructs and to identify new target antigens. Even though the Food and Drug Administration has approved commercialization of some CD19 CART cell therapies, there are still some limitations that restrict their widespread clinical use. The manufacture of autologous products for individual patients is logistically cumbersome and expensive and allogeneic T cell products may pose an appreciable risk of graft-versus-host disease (GVHD).Areas covered:Natural killer (NK) cells are an attractive alternative for CART-based immunotherapies. They have the innate ability to detect and eliminate malignant cells and are safer in the 'off-the-shelf' setting. This review discusses the current progress within the CAR NK cell field, including the challenges, and future prospects. Gene engineered NK cells was used as the search term in PubMed and Google Scholar through to December 2020.Expert opinion:CAR NK cell therapies hold promise as an 'off-the-shelf' cell therapy for cancer. It is hoped that an enhanced understanding of their immunobiology and molecular mechanisms of action will improve their in vivo potency.

Harnessing NK cells for cancer immunotherapy: immune checkpoint receptors and chimeric antigen receptors

Natural killer (NK) cells, key antitumor effectors of the innate immune system, are endowed with the unique ability to spontaneously eliminate cells undergoing a neoplastic transformation. Given their broad reactivity against diverse types of cancer and close association with cancer prognosis, NK cells have gained considerable attention as a promising therapeutic target for cancer immunotherapy. NK cell-based therapies have demonstrated favorable clinical efficacies in several hematological malignancies but limited success in solid tumors, thus highlighting the need to develop new therapeutic strategies to restore and optimize antitumor activity while preventing tumor immune escape. The current therapeutic modalities yielding encouraging results in clinical trials include the blockade of immune checkpoint receptors to overcome the immune-evasion mechanism used by tumors and the incorporation of tumor-directed chimeric antigen receptors to enhance NK cell antitumor specificity and activity. These observations, together with recent advances in the understanding of NK cell activation within the tumor microenvironment, will facilitate the optimal design of NK cell-based therapy against a broad range of cancers and, more desirably, refractory cancers.

How to Combine the Two Landmark Treatment Methods-Allogeneic Hematopoietic Stem Cell Transplantation and Chimeric Antigen Receptor T Cell Therapy Together to Cure High-Risk B Cell Acute Lymphoblastic Leukemia?

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has made tremendous progress in the last few decades and is increasingly being used worldwide. The success of haploidentical HSCT has made it possible to have "a donor for everyone". Patients who received transplantation in remission may have a favorable outcome, while those who were transplanted in advanced stages of disease have a poor prognosis. Although chimeric antigen receptor T (CAR-T) cell therapy is currently a milestone in the immunotherapy of relapsed or refractory (R/R) B cell acute lymphoblastic leukemia (B-ALL) and has demonstrated high remission rates in patients previously treated in multiple lines, the relatively high relapse rate remains a barrier to CAR-T cell therapy becoming an excellent cure option. Therefore, combining these two approaches (allo-HSCT and CAR-T cell therapy) is an attractive area of research to further improve the prognosis of R/R B-ALL. In this review, we will discuss the current clinical practices of combining allo-HSCT with CAR-T cell therapy based on available data, including CAR-T cells as a bridge to allo-HSCT for R/R B-ALL and CAR-T cell infusion for post-transplant relapse. We will further explore not only other possible ways to combine the two approaches, including CAR-T cell therapy to clear minimal residual disease peri-transplantation and incorporation of CAR technology to treat graft-versus-host disease, but also the potential of CAR-T cells as a part of allo-HSCT.

Immune effector cell-associated neurotoxicity syndrome: A therapeutic approach in the critically ill

Immunotherapy with chimeric antigen-specific receptor modified T cells, known as CAR-T, is emerging as a promising approach to hematological malignancies. In this regard, CAR-T against human cluster of differentiation (CD) 19 has demonstrated antitumor efficacy in application to B cell neoplasms resistant to conventional therapy. However, activation of the immune system induces severe and specific complications which can prove life-threatening. These include cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome (known as ICANS) - the latter being the subject of the present review. Although the physiopathological mechanisms underlying ICANS are not well known, a number of clinical and biological factors increase the risk of developing neurotoxicity associated to CAR-T therapy. Treatment is based on close monitoring, measures of support, anticonvulsivants, corticosteroids, and early admission to intensive care. The present study offers a comprehensive review of the available literature from a multidisciplinary perspective, including recommendations from intensivists, neurologists and hematologists dedicated to the care of critically ill adults.

CRISPR/Cas9 in Cancer Immunotherapy: Animal Models and Human Clinical Trials

Even though chemotherapy and immunotherapy emerged to limit continual and unregulated proliferation of cancer cells, currently available therapeutic agents are associated with high toxicity levels and low success rates. Additionally, ongoing multi-targeted therapies are limited only for few carcinogenesis pathways, due to continually emerging and evolving mutations of proto-oncogenes and tumor-suppressive genes. CRISPR/Cas9, as a specific gene-editing tool, is used to correct causative mutations with minimal toxicity, but is also employed as an adjuvant to immunotherapy to achieve a more robust immunological response. Some of the most critical limitations of the CRISPR/Cas9 technology include off-target mutations, resulting in nonspecific restrictions of DNA upstream of the Protospacer Adjacent Motifs (PAM), ethical agreements, and the lack of a scientific consensus aiming at risk evaluation. Currently, CRISPR/Cas9 is tested on animal models to enhance genome editing specificity and induce a stronger anti-tumor response. Moreover, ongoing clinical trials use the CRISPR/Cas9 system in immune cells to modify genomes in a target-specific manner. Recently, error-free in vitro systems have been engineered to overcome limitations of this gene-editing system. The aim of the article is to present the knowledge concerning the use of CRISPR Cas9 technique in targeting treatment-resistant cancers. Additionally, the use of CRISPR/Cas9 is aided as an emerging supplementation of immunotherapy, currently used in experimental oncology. Demonstrating further, applications and advances of the CRISPR/Cas9 technique are presented in animal models and human clinical trials. Concluding, an overview of the limitations of the gene-editing tool is proffered.

Preclinical Assessment of Efficacy and Safety Analysis of CAR-T Cells (ISIKOK-19) Targeting CD19-Expressing B-Cells for the First Turkish Academic Clinical Trial with Relapsed/Refractory ALL and NHL Patients

Objective:

Relapsed and refractory CD19-positive B-cell acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphoma (NHL) are the focus of studies on hematological cancers. Treatment of these malignancies has undergone recent transformation with the development of new gene therapy and molecular biology techniques, which are safer and well-tolerated therapeutic approaches. The CD19 antigen is the most studied therapeutic target in these hematological cancers. This study reports the results of clinical-grade production, quality control, and in vivo efficacy processes of ISIKOK-19 cells as the first academic clinical trial of CAR-T cells targeting CD19-expressing B cells in relapsed/refractory ALL and NHL patients in Turkey.

Materials and Methods:

We used a lentiviral vector encoding the CD19 antigen-specific antibody head (FMC63) conjugated with the CD8-CD28-CD3ζ sequence as a chimeric antigen receptor (CAR) along with a truncated form of EGFR (EGFRt) on human T-lymphocytes (CAR-T). We preclinically assessed the efficacy and safety of the manufactured CAR-T cells, namely ISIKOK-19, from both healthy donors’ and ALL/NHL patients’ peripheral blood mononuclear cells.

Results:

We showed significant enhancement of CAR lentivirus transduction efficacy in T-cells using BX-795, an inhibitor of the signaling molecule TBK1/IKKƐ, in order to cut the cost of CAR-T cell production. In addition, ISIKOK-19 cells demonstrated a significantly high level of cytotoxicity specifically against a CD19+ B-lymphocyte cancer model, RAJI cells, in NOD/SCID mice.

Conclusion:

This is the first report of preclinical assessment of efficacy and safety analysis of CAR-T cells (ISIKOK-19) targeting CD19-expressing B cells in relapsed/refractory ALL and NHL patients in Turkey.

CAR-T design: Elements and their synergistic function

Chimeric antigen receptor (CAR) T cells use re-engineered cell surface receptors to specifically bind to and lyse oncogenic cells. Two clinically approved CAR-T–cell therapies have significant clinical efficacy in treating CD19-positive B cell cancers. With widespread interest to deploy this immunotherapy to other cancers, there has been great research activity to design new CAR structures to increase the range of targeted cancers and anti-tumor efficacy. However, several obstacles must be addressed before CAR-T–cell therapies can be more widely deployed. These include limiting the frequency of lethal cytokine storms, enhancing T-cell persistence and signaling, and improving target antigen specificity. We provide a comprehensive review of recent research on CAR design and systematically evaluate design aspects of the four major modules of CAR structure: the ligand-binding, spacer, transmembrane, and cytoplasmic domains, elucidating design strategies and principles to guide future immunotherapeutic discovery.

Surmounting the obstacles that impede effective CAR T cell trafficking to solid tumors

Innovative immunotherapies based on immune checkpoint targeting antibodies and engineered T cells are transforming the way we approach cancer treatment. However, although these T cell centered strategies result in marked and durable responses in patients across many different tumor types, they provide therapeutic efficacy only in a proportion of patients. A major challenge of immuno‐oncology is thereby to identify mechanisms responsible for resistance to cancer immunotherapy in order to overcome them via adapted strategies that will ultimately improve intrinsic efficacy and response rates. Here, we focus on the barriers that restrain the trafficking of chimeric antigen receptor (CAR)‐expressing T cells to solid tumors. Upon infusion, CAR T cells need to home into malignant sites, navigate within complex tumor environments, form productive interactions with cancer cells, deliver their cytotoxic activities, and finally persist. We review the accumulating evidence that the microenvironment of solid tumors contains multiple obstacles that hinder CAR T cells in the dynamic steps underlying their trafficking. We focus on how these hurdles may in part account for the failure of CAR T cell clinical trials in human carcinomas. Given the engineered nature of CAR T cells and possibilities to modify the tumor environment, there are ample opportunities to augment CAR T cell ability to efficiently find and combat tumors. We present some of these strategies, which represent a dynamic field of research with high potential for clinical applicability.

Anti-αFR CAR-engineered NK-92 Cells Display Potent Cytotoxicity Against αFR-positive Ovarian Cancer

Folate receptor alpha (αFR) is overexpressed in 90% of ovarian cancers, one of the most lethal gynecologic cancers. Recent studies have suggested that natural killer (NK) cells may be better chimeric antigen receptor (CAR) drivers because of their favorable innate characteristics, such as directly recognizing and killing tumor cells. However, the therapeutic effects of CAR-engineered NK cells targeting αFR in ovarian cancer have not been reported. In this research, 3 generations of anti-αFR CAR were constructed, namely αFR-ζ (first generation), αFR-28ζ (second generation), and αFR-28BBζ (third generation), and were highly expressed on the surface of NK-92 cells by lentivirus gene transfection. Three anti-αFR CAR-engineered NK-92 cells can specifically kill αFR-positive tumor cells in vitro, especially ovarian cancer cells with high αFR expression. Compared with NK-92 cells expressing αFR-ζ or αFR-28ζ, NK-92 cells expressing αFR-28BBζ showed not only higher antigen-specific cytotoxicity and proliferation but also lower antigen-induced apoptosis. Moreover, stronger degranulation and cytokine secretion were detected in NK-92 cells expressing αFR-28BBζ cocultured with αFR-positive tumor cells. Real-time cell analysis and live cell imaging recorded the process of NK-92 cells expressing αFR-28BBζ killing ovarian cancer cells in vitro. Furthermore, NK-92 cells expressing αFR-28BBζ can effectively eliminate cancer cells in a mouse xenograft model of ovarian cancer and significantly prolong the survival of tumor-bearing mice. These results demonstrate that the anti-αFR CARs redirect NK-92 cells with specific antitumor activity, and the third-generation anti-αFR CAR-engineered NK-92 cells display more potent cytotoxicity against αFR-positive ovarian cancer, laying the foundation for future clinical research.

Art and Science of the Cellular Mesoscale

Experimental information from microscopy, structural biology, and bioinformatics may be integrated to build structural models of entire cells with molecular detail. This integrative modeling is challenging in several ways: the intrinsic complexity of biology results in models with many closely packed and heterogeneous components; the wealth of available experimental data is scattered among multiple resources and must be gathered, reconciled, and curated; and computational infrastructure is only now gaining the capability of modeling and visualizing systems of this complexity. We present recent efforts to address these challenges, both with artistic approaches to depicting the cellular mesoscale, and development and application of methods to build quantitative models.

Point-Of-Care CAR T-Cell Production (ARI-0001) Using a Closed Semi-automatic Bioreactor: Experience From an Academic Phase I Clinical Trial

Development of semi-automated devices that can reduce the hands-on time and standardize the production of clinical-grade CAR T-cells, such as CliniMACS Prodigy from Miltenyi, is key to facilitate the development of CAR T-cell therapies, especially in academic institutions. However, the feasibility of manufacturing CAR T-cell products from heavily pre-treated patients with this system has not been demonstrated yet. Here we report and characterize the production of 28 CAR T-cell products in the context of a phase I clinical trial for CD19+ B-cell malignancies (NCT03144583). The system includes CD4-CD8 cell selection, lentiviral transduction and T-cell expansion using IL-7/IL-15. Twenty-seven out of 28 CAR T-cell products manufactured met the full list of specifications and were considered valid products. Ex vivo cell expansion lasted an average of 8.5 days and had a mean transduction rate of 30.6 ± 13.44%. All products obtained presented cytotoxic activity against CD19+ cells and were proficient in the secretion of pro-inflammatory cytokines. Expansion kinetics was slower in patient's cells compared to healthy donor's cells. However, product potency was comparable. CAR T-cell subset phenotype was highly variable among patients and largely determined by the initial product. T_CM and T_EM were the predominant T-cell phenotypes obtained. 38.7% of CAR T-cells obtained presented a T_N or T_CM phenotype, in average, which are the subsets capable of establishing a long-lasting T-cell memory in patients. An in-depth analysis to identify individual factors contributing to the optimal T-cell phenotype revealed that ex vivo cell expansion leads to reduced numbers of T_N, T_SCM, and T_EFF cells, while T_CM cells increase, both due to cell expansion and CAR-expression. Overall, our results show for the first time that clinical-grade production of CAR T-cells for heavily pre-treated patients using CliniMACS Prodigy system is feasible, and that the obtained products meet the current quality standards of the field. Reduced ex vivo expansion may yield CAR T-cell products with increased persistence in vivo.

Engineering primary T cells with chimeric antigen receptors for rewired responses to soluble ligands

The expression of synthetic receptors in primary T cells enables the programming of user-defined responses when designing T-cell therapies. Chimeric antigen receptors (CARs) are synthetic receptors that have demonstrated efficacy in cancer therapy by targeting immobilized antigens on the surface of malignant cells. Recently, we showed they can also rewire T-cell responses to soluble ligands. In contrast to other synthetic receptors, CARs are not only readily engineered by rational design, but also clinically translatable, with robust function in primary human T cells. This protocol discusses design principles for CARs responsive to soluble ligands and delineates steps for producing T cells expressing synthetic receptors. Functional assays for quantifying the ability of CAR T cells to sense and respond to soluble ligands are also presented. This protocol provides a framework for proficient immune-cell researchers to test novel T-cell therapies targeting soluble ligands in <2 weeks.

Rational Design of a Bifunctional AND-Gate Ligand To Modulate Cell-Cell Interactions

Protein "AND-gate" systems, in which a ligand acts only on cells with two different receptors, direct signaling activity to a particular cell type and avoid action on other cells. In a bifunctional AND-gate protein, the molecular geometry of the protein domains is crucial. Here we constructed a tissue-targeted erythropoietin (EPO) that stimulates red blood cell (RBC) production without triggering thrombosis. The EPO was directed to RBC precursors and mature RBCs by fusion to an anti-glycophorin A antibody V region. Many such constructs activated EPO receptors in vitro and stimulated RBC and not platelet production in mice but nonetheless enhanced thrombosis in mice and caused adhesion between RBCs and EPO-receptor-bearing cells. On the basis of a protein-structural model of the RBC surface, we rationally designed an anti-glycophorin-EPO fusion that does not induce cell adhesion in vitro or enhance thrombosis in vivo. Thus, mesoscale geometry can inform the design of synthetic-biological systems.

PSCA is a target of chimeric antigen receptor T cells in gastric cancer

Background

Gastric cancer is a deadly malignancy and is a prognostically unfavorable entity with restricted therapeutic strategies available. Prostate stem cell antigen (PSCA) is a glycosylphosphatidylinositol (GPI)-anchored cell surface protein widely expressed in bladder, prostate, and pancreatic cancers. Existing studies have thoroughly recognized the availability of utilizing anti-PSCA CAR-T cells in the treatment of metastatic prostate cancer and non-small-cell lung cancer. However, no previous study has investigated the feasibility of using anti-PSCA CAR-T cells to treat gastric cancer, irrespective of the proven expression of PSCA on the gastric cancer cell surface.

Methods

We determined the expression of PSCA in several primary tumor tissues and constructed third-generation anti-PSCA CAR-T cells. We then incubated anti-PSCA CAR-T cells and GFP-T cells with target tumor cell lines at E:T ratios of 2:1, 1:1, 1:2, and 1:4 to evaluate the therapeutic efficacy of anti-PSCA CAR-T cells in vitro. We also assayed canonical T cell activation markers after coculturing anti-PSCA CAR-T cells with target cell lines by flow cytometry. The detection of a functional cytokine profile was carried out via enzyme-linked immunosorbent assays. We then evaluated the antitumor activity of anti-PSCA CAR-T cells in vivo by establishing two different xenograft GC mouse models.

Results

Anti-PSCA CAR-T cells exhibited upregulated activation markers and increased cytokine production profiles related to T cell cytotoxicity in an antigen-dependent manner. Moreover, anti-PSCA CAR-T cells exhibited robust anti-tumor cytotoxicity in vitro. Importantly, we demonstrated that anti-PSCA CAR-T cells delivered by peritumoral injection successfully stunted tumor progression in vivo. However, intravenous administration of anti-PSCA CAR-T cells failed to reveal any therapeutic improvements.

Conclusions

Our findings corroborated the feasibility of anti-PSCA CAR-T cells and their efficacy against gastric cancer, implicating the potential of applying anti-PSCA CAR-T cells to treat GC patients in the clinic.

Chimeric antigen receptor -T cell therapy: Applications and challenges in treatment of allergy and asthma

Despite the current advancements, cancer treatment approaches have limitations restricting their cure rate. Immunotherapy techniques are among novel and promising cancer therapeutic approaches. Therapeutic antibodies and adoptive cell therapy (ACT) are the main branches of immunotherapy. T lymphocytes and genetically engineered cells are among important cells which can be used in ACT. This review has focused on recent advances in engineered cell-based immunotherapy based on T lymphocytes with chimeric antigen receptors (CARs). CARs are recombinant receptors expressing T cell signaling domains with or without co-stimulatory molecules. CAR-T cells are expanded ex vivo and re-infused to patients in order to improve their therapeutic efficacy. Nowadays, the beneficial function of CAR-T cell therapy has been indicated in various diseases including hematological malignancies, solid tumors, autoimmune diseases, and allergic diseases such as asthma. Furthermore, antigen-specific T regulatory cells (T_regs) and gene-edited T cells seem to be beneficial in controlling inflammation in allergic asthma. In fact, dysregulated function of T_regs is responsible for dominance of T helper 2 immune response and progression of allergic asthma. CAR-T_reg cells can also be designed and reproduced using iT_reg population to manage asthma. In addition, universal CAR-T cells can be modified to selectively target multiple antigens. The fourth generation CAR-T cells (i.e. TRUCK cells) represent novel strategies to cure asthma and allergic diseases as well. Despite the advantages of CAR-T cells, their applications can be associated with some unwanted reactions such as cytokine storm, anaphylaxis, neurotoxicity, etc. For clinical application, there is a need to prevent and manage these complications by optimizing ACT protocols.

The Role of Checkpoint Inhibitors and Cytokines in Adoptive Cell-Based Cancer Immunotherapy with Genetically Modified T Cells

This review focuses on the structure and molecular action mechanisms of chimeric antigen receptors (CARs) and major aspects of the manufacturing and clinical application of products for the CAR-T (CAR-modified T lymphocyte) therapy of hematological and solid tumors with special emphasis on the strategies for combined use of CAR-T therapy with immuno-oncological monoclonal antibodies (checkpoint inhibitors) and cytokines to boost survival, persistence, and antitumor efficacy of CAR-T therapy. The review also summarizes preclinical and clinical data on the additive effects of the combined use of CAR-T therapy with interleukins and monoclonal antibodies targeting immune checkpoints.

Chimeric Antigen Receptor T Cell Immunotherapy for Tumor: A Review of Patent Literatures

BACKGROUND

Chimeric Antigen Receptor (CAR) T cell immunotherapy, as an innovative method for tumor immunotherapy, acquires unprecedented clinical outcomes. Genetic modification not only provides T cells with the antigen-binding function but also endows T cells with better immunological functions both in solid and hematological cancer. However, the CAR T cell therapy is not perfect because of several reasons, such as tumor immune microenvironment, and autologous limiting factors of CAR T cells. Moreover, the safety of CAR T cells should be improved.

OBJECTIVE

Recently many patents and publications have reported the importance of CAR T cell immunotherapy. Based on the patents about CAR T cell immunotherapy, we conclude some methods for designing the CAR which can provide useful information to readers.

METHODS

This review presents recent patents and publications, summarizes some specific antigens for oncotherapy from patents and enumerate some approaches to treatment of immunosuppression and reinforcing the immune response of CAR T cells. We also sum up some strategies for improving the safety of CAR T cell immunotherapy.

RESULTS

CAR T cell immunotherapy as a neotype cellular immunotherapy has been proved effective in oncotherapy and authorized by the FDA. Improvements in CAR designing have enhanced the functions of CAR T cells.

CONCLUSION

This review, summarizing antigens and approaches to overcome defects of CAR T cell immunotherapy from patents and publications, might contribute to a broad readership.

Molecular Design, Optimization, and Genomic Integration of Chimeric B Cell Receptors in Murine B Cells

Immune cell therapies based on the integration of synthetic antigen receptors comprise a powerful strategy for the treatment of diverse diseases, most notably T cells engineered to express chimeric antigen receptors (CAR) for targeted cancer therapy. In addition to T lymphocytes, B lymphocytes may also represent valuable immune cells that can be engineered for therapeutic purposes such as protein replacement therapy or recombinant antibody production. In this article, we report a promising concept for the molecular design, optimization, and genomic integration of a novel class of synthetic antigen receptors, chimeric B cell receptors (CBCR). We initially optimized CBCR expression and detection by modifying the extracellular surface tag, the transmembrane regions and intracellular signaling domains. For this purpose, we stably integrated a series of CBCR variants using CRISPR-Cas9 into immortalized B cell hybridomas. Subsequently, we developed a reliable and consistent pipeline to precisely introduce cassettes of several kb size into the genome of primary murine B cells also using CRISPR-Cas9 induced HDR. Finally, we were able to show the robust surface expression and antigen recognition of a synthetic CBCR in primary B cells. We anticipate CBCRs and our approach for engineering primary B cells will be a valuable tool for the advancement of future B cell- based immune cell therapies.

Cell penetrating peptide functionalized perfluorocarbon nanoemulsions for targeted cell labeling and enhanced fluorine-19 MRI detection

PURPOSE

A bottleneck in developing cell therapies for cancer is assaying cell biodistribution, persistence, and survival in vivo. Ex vivo cell labeling using perfluorocarbon (PFC) nanoemulsions, paired with ¹⁹ F MRI detection, is a non-invasive approach for cell product detection in vivo. Lymphocytes are small and weakly phagocytic limiting PFC labeling levels and MRI sensitivity. To boost labeling, we designed PFC nanoemulsion imaging probes displaying a cell-penetrating peptide, namely the transactivating transcription sequence (TAT) of the human immunodeficiency virus. We report optimized synthesis schemes for preparing TAT co-surfactant to complement the common surfactants used in PFC nanoemulsion preparations.

METHODS

We performed ex vivo labeling of primary human chimeric antigen receptor (CAR) T cells with nanoemulsion. Intracellular labeling was validated using electron microscopy and confocal imaging. To detect signal enhancement in vivo, labeled CAR T cells were intra-tumorally injected into mice bearing flank glioma tumors.

RESULTS

By incorporating TAT into the nanoemulsion, a labeling efficiency of ~10¹² fluorine atoms per CAR T cell was achieved that is a >8-fold increase compared to nanoemulsion without TAT while retaining high cell viability (~84%). Flow cytometry phenotypic assays show that CAR T cells are unaltered after labeling with TAT nanoemulsion, and in vitro tumor cell killing assays display intact cytotoxic function. The ¹⁹ F MRI signal detected from TAT-labeled CAR T cells was 8 times higher than cells labeled with PFC without TAT.

CONCLUSION

The peptide-PFC nanoemulsion synthesis scheme presented can significantly enhance cell labeling and imaging sensitivity and is generalizable for other targeted imaging probes.

Chimeric Antigen Receptor-T Cells for Targeting Solid Tumors: Current Challenges and Existing Strategies

Chimeric antigen receptor-T cells (CAR-Ts) are an exciting new cancer treatment modality exemplified by the recent regulatory approval of two CD19-targeted CAR-T therapies for certain B cell malignancies. However, this success in the hematological setting has yet to translate to a significant level of objective clinical responses in the solid tumor setting. The reason for this lack of translation undoubtedly lies in the substantial challenges raised by solid tumors to all therapies, including CAR-T, that differ from B cell malignancies. For instance, intravenously infused CAR-Ts are likely to make rapid contact with cancerous B cells since both tend to reside in the same vascular compartments within the body. By contrast, solid cancers tend to form discrete tumor masses with an immune-suppressive tumor microenvironment composed of tumor cells and non-tumor stromal cells served by abnormal vasculature that restricts lymphocyte infiltration and suppresses immune function, expansion, and persistence. Moreover, the paucity of uniquely and homogeneously expressed tumor antigens and inherent plasticity of cancer cells provide major challenges to the specificity, potency, and overall effectiveness of CAR-T therapies. This review focuses on the major preclinical and clinical strategies currently being pursued to tackle these challenges in order to drive the success of CAR-T therapy against solid tumors.

Improved survival of chimeric antigen receptor-engineered T (CAR-T) and tumor-specific T cells caused by anti-programmed cell death protein 1 single-chain variable fragment-producing CAR-T cells

Chimeric antigen receptor‐engineered T (CAR‐T)‐cell therapy holds significant promise for the treatment of hematological malignancies, especially for B‐cell leukemia and lymphoma. However, its efficacy against non‐hematological malignancies has been limited as a result of several biological problems characteristic of the tumor microenvironment of solid tumors. One of the main hurdles is the heterogeneous nature of tumor‐associated antigens (TAA) expressed in solid tumors. Another hurdle is the inefficient activation and limited persistence of CAR‐T cells, mainly as a result of T‐cell exhaustion caused by immunosuppressive factors in the tumor microenvironment. In the present study, to address these problems, we engineered CAR‐T cells to produce antagonistic anti‐programmed cell death protein 1 (PD‐1) single‐chain variable fragment (scFv), by which PD‐1‐dependent inhibitory signals in CAR‐T cells and adjacent tumor‐specific non‐CAR‐T cells are attenuated. In mouse solid tumor models, PD‐1 scFv‐producing CAR‐T cells induced potent therapeutic effects superior to those of conventional CAR‐T cells, along with a significant reduction of apoptotic cell death not only in CAR‐T cells themselves but also in TAA‐specific T cells in the tumor tissue. In addition, the treatment with anti‐PD‐1 scFv‐producing CAR‐T cells resulted in an increased concentration of PD‐1 scFv in tumor tissue but not in sera, suggesting an induction of less severe systemic immune‐related adverse events. Hence, the present study developed anti‐PD‐1 scFv‐producing CAR‐T cell technology and explored its cellular mechanisms underlying potent antitumor efficacy.

PiggyBac-modified CD19-expressing 4T1 cell line for the evaluation of CAR construct

Reliable and stable target cell lines are required for evaluating the efficiency and studying the mechanism of chimeric antigen receptor T (CAR-T) immunotherapy both in vitro and in vivo. Jurkat cells can be used as an alternative for human primary lymphocytes to evaluate the constructs and function of the "CAR". This study established a murine 4T1-CD19 cell line that stably expressed a cd19 gene. The 4T1-CD19 cells had similar growth kinetics to its parent cell 4T1. The protein CD19 expression of the 4T1-CD19 was detected by reverse transcription-polymerase chain reaction (RT-PCR) and western blot. The second-generation CAR was constructed and transfected into Jurkat cells. The expression of CAR protein was analyzed by flow cytometry and western blot. Finally, the interaction between the CAR and CD19 was confirmed by the upregulation of the IL-2 mRNA level of Jurkat-CAR stimulated by 4T1-CD19. Therefore, the 4T1-CD19 cell line and Jurkat-CAR have been successfully established, and may be used to access the function of various CAR constructs both in vitro and in vivo.