Logic-gated approaches to extend the utility of chimeric antigen receptor T-cell technology

Arming CAR-T cells with cytokines and more: Innovations in the fourth-generation CAR-T development

Chimeric antigen receptor T cells (CAR-T) therapy has shown great potential in tumor treatment. However, many factors impair the efficacy of CAR-T therapy, such as antigenic heterogeneity and loss, limited potency and persistence, poor infiltration capacity, and a suppressive tumor microenvironment. To overcome these obstacles, recent studies have reported a new generation of CAR-T cells expressing cytokines called armored CAR-T, TRUCK-T, or the fourth-generation CAR-T. Here we summarize the strategies of arming CAR-T cells with natural or synthetic cytokine signals to enhance their anti-tumor capacity. Moreover, we summarize the advances in CAR-T cells expressing non-cytokine proteins, such as membrane receptors, antibodies, enzymes, co-stimulatory molecules, and transcriptional factors. Furthermore, we discuss several prospective strategies for armored CAR-T therapy development. Altogether, these ideas may provide new insights for the innovations of the next-generation CAR-T therapy.

Targeting the dendritic cell-T cell axis to develop effective immunotherapies for glioblastoma

Glioblastoma is an aggressive primary brain tumor that has seen few advances in treatments for over 20 years. In response to this desperate clinical need, multiple immunotherapy strategies are under development, including CAR-T cells, immune checkpoint inhibitors, oncolytic viruses and dendritic cell vaccines, although these approaches are yet to yield significant clinical benefit. Potential reasons for the lack of success so far include the immunosuppressive tumor microenvironment, the blood-brain barrier, and systemic changes to the immune system driven by both the tumor and its treatment. Furthermore, while T cells are essential effector cells for tumor control, dendritic cells play an equally important role in T cell activation, and emerging evidence suggests the dendritic cell compartment may be deeply compromised in glioblastoma patients. In this review, we describe the immunotherapy approaches currently under development for glioblastoma and the challenges faced, with a particular emphasis on the critical role of the dendritic cell-T cell axis. We suggest a number of strategies that could be used to boost dendritic cell number and function and propose that the use of these in combination with T cell-targeting strategies could lead to successful tumor control.

Chimeric antigen receptor T cell and regulatory T cell therapy in non-oncology diseases: A narrative review of studies from 2017 to 2023

Recently, the remarkable success of chimeric antigen receptor T cell (CAR-T) therapy in treating certain tumors has led to numerous studies exploring its potential application to treat non-oncology diseases. This review discusses the progress and evolution of CAR-T cell therapies for treating non-oncology diseases over the past 5 years. Additionally, we summarize the advantages and disadvantages of CAR-T cell therapy in treating non-oncological diseases and identify any difficulties that should be overcome. After conducting an in-depth analysis of the most recent studies on CAR-T technology, we discuss the key elements of CAR-T therapy, such as developing an effective CAR design for non-oncological diseases, controlling the rate and duration of response, and implementing safety measures to reduce toxicity. These studies provide new insights into different delivery strategies, the discovery of new target molecules, and improvements in the safety of CAR-T therapy for non-oncological diseases.

Challenges to addressing the unmet medical needs for immunotherapy targeting cold colorectal cancer

With the establishment of the immune surveillance mechanism since the 1950s, attempts have been made to activate the immune system for cancer treatment through the discovery of various cytokines or the development of antibodies up to now. The fruits of these efforts have contributed to the recognition of the 3^rd generation of anticancer immunotherapy as the mainstream of cancer treatment. However, the limitations of cancer immunotherapy are also being recognized through the conceptual establishment of cold tumors recently, and colorectal cancer (CRC) has become a major issue from this therapeutic point of view. Here, it is emphasized that non-clinical strategies to overcome the immunosuppressive environment and clinical trials based on these basic investigations are being made on the journey to achieve better treatment outcomes for the treatment of cold CRC.

Advances in modular control of CAR-T therapy with adapter-mediated CARs

Protein engineering has contributed to successes in the field of T cell-based immunotherapy, including chimeric antigen receptor (CAR) T cell therapy. CAR T cell therapy has become a pillar of cancer immunotherapy, demonstrating clinical effectiveness against B cell malignancies by targeting the B cell antigen CD19. Current gene editing techniques have limited safety controls over CAR T cell activity, which presents a hurdle for control of CAR T cells in patients. Alternatively, CAR T cell activity can be controlled by engineering CARs to bind soluble adapter molecules that direct the interaction between the CAR T cell and target cell. The flexibility in this adapter-mediated approach overcomes the rigid specificity of traditional CAR T cells to allow targeting of multiple cell types. Here we describe adapter CAR T technologies and how these methods emphasize the growing role of protein engineering in the design of programmable tools for T cell therapies.

Development of Cancer Immunotherapies

Cancer immunotherapy, or the utilization of components of the immune system to target and eliminate cancer, has become a highly active area of research in the past several decades and a common treatment strategy for several cancer types. The concept of harnessing the immune system for this purpose originated over 100 years ago when a physician by the name of William Coley successfully treated several of his cancer patients with a combination of live and attenuated bacteria, later known as "Coley's Toxins", after observing a subset of prior patients enter remission following their diagnosis with the common bacterial infection, erysipelas. However, it was not until late in the twentieth century that cancer immunotherapies were developed for widespread use, thereby transforming the treatment landscape of numerous cancer types. Pivotal studies elucidating molecular and cellular functions of immune cells, such as the discovery of IL-2 and production of monoclonal antibodies, fostered the development of novel techniques for studying the immune system and ultimately the development and approval of several cancer immunotherapies by the United States Food and Drug Association in the 1980s and 1990s, including the tuberculosis vaccine-Bacillus Calmette-Guérin, IL-2, and the CD20-targeting monoclonal antibody. Approval of the first therapeutic cancer vaccine, Sipuleucel-T, for the treatment of metastatic castration-resistant prostate cancer and the groundbreaking success and approval of immune checkpoint inhibitors and chimeric antigen receptor T cell therapy in the last decade, have driven an explosion of interest in and pursuit of novel cancer immunotherapy strategies. A broad range of modalities ranging from antibodies to adoptive T cell therapies is under investigation for the generalized treatment of a broad spectrum of cancers as well as personalized medicine. This chapter will focus on the recent advances, current strategies, and future outlook of immunotherapy development for the treatment of cancer.

Network models of prostate cancer immune microenvironments identify ROMO1 as heterogeneity and prognostic marker

Prostate cancer (PCa) is the fifth leading cause of death from cancer in men worldwide. Its treatment remains challenging due to the heterogeneity of the tumor, mainly because of the lack of effective and targeted prognostic markers at the system biology level. First, the data were retrieved from TCGA dataset, and valid samples were obtained by consistent clustering and principal component analysis; next, key genes were analyzed for prognosis of PCa using WGCNA, MEGENA, and LASSO Cox regression model analysis, while key genes were screened based on disease-free survival significance. Finally, TIMER data were selected to explore the relationship between genes and tumor immune infiltration, and GSCAlite was used to explore the small-molecule targeted drugs that act with them. Here, we used tumor subtype analysis and an energetic co-expression network algorithm of WGCNA and MEGENA to identify a signal dominated by the ROMO1 to predict PCa prognosis. Cox regression analysis of ROMO1 was an independent influence, and the prognostic value of this biomarker was validated in the training set, the validated data itself, and external data, respectively. This biomarker correlates with tumor immune infiltration and has a high degree of infiltration, poor prognosis, and strong correlation with CD8+T cells. Gene function annotation and other analyses also implied a potential molecular mechanism for ROMO1. In conclusion, we putative ROMO1 as a portal key prognostic gene for the diagnosis and prognosis of PCa, which provides new insights into the diagnosis and treatment of PCa.

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.

Targeting Acute Myeloid Leukemia Using the RevCAR Platform: A Programmable, Switchable and Combinatorial Strategy

Simple Summary

Acute myeloid leukemia (AML) is a type of blood malignancy particularly affecting the myeloid lineage and one of the most common types of leukemia in adults. It is characterized by high heterogeneity among patients leading to immune escape and disease relapse, which challenges the development of immunotherapies such as chimeric antigen receptor (CAR) T-cells. In this way, the aim of our work was to establish the modular RevCAR platform as a combinatorial tumor targeting approach for the treatment of AML. Herein, we demonstrate the preclinical flexibility and efficiency of RevCAR T-cells in targeting patient-derived AML cells expressing CD33 and CD123. Furthermore, AND gate logic targeting these antigens was successfully established using the RevCAR platform. These accomplishments pave the way towards the future clinical translation of such an improved and personalized immunotherapy for AML patients aiming long-lasting anticarcinogenic responses.

Abstract

Clinical translation of novel immunotherapeutic strategies such as chimeric antigen receptor (CAR) T-cells in acute myeloid leukemia (AML) is still at an early stage. Major challenges include immune escape and disease relapse demanding for further improvements in CAR design. To overcome such hurdles, we have invented the switchable, flexible and programmable adaptor Reverse (Rev) CAR platform. This consists of T-cells engineered with RevCARs that are primarily inactive as they express an extracellular short peptide epitope incapable of recognizing surface antigens. RevCAR T-cells can be redirected to tumor antigens and controlled by bispecific antibodies cross-linking RevCAR T- and tumor cells resulting in tumor lysis. Remarkably, the RevCAR platform enables combinatorial tumor targeting following Boolean logic gates. We herein show for the first time the applicability of the RevCAR platform to target myeloid malignancies like AML. Applying in vitro and in vivo models, we have proven that AML cell lines as well as patient-derived AML blasts were efficiently killed by redirected RevCAR T-cells targeting CD33 and CD123 in a flexible manner. Furthermore, by targeting both antigens, a Boolean AND gate logic targeting could be achieved using the RevCAR platform. These accomplishments pave the way towards an improved and personalized immunotherapy for AML patients.

Advances in chimeric antigen receptor T-cell therapy for B-cell non-Hodgkin lymphoma

B-cell non-Hodgkin lymphoma (B-NHL) is a group of heterogeneous disease which remains incurable despite developments of standard chemotherapy regimens and new therapeutic agents in decades. Some individuals could have promising response to standard therapy while others are unresponsive to standard chemotherapy or relapse after autologous hematopoietic stem-cell transplantation (ASCT), which indicates the necessity to develop novel therapies for refractory or relapsed B-NHLs. In recent years, a novel cell therapy, chimeric antigen receptor T-cell therapy (CAR-T), was invented to overcome the limitation of traditional treatments. Patients with aggressive B-NHL are considered for CAR-T cell therapy when they have progressive lymphoma after second-line chemotherapy, relapse after ASCT, or require a third-line therapy. Clinical trials of anti-CD19 CAR-T cell therapy have manifested encouraging efficacy in refractory or relapsed B-NHL. However, adverse effects of this cellular therapy including cytokine release syndrome, neurotoxicity, tumor lysis syndrome and on-target, off-tumor toxicities should attract our enough attention despite the great anti-tumor effects of CAR-T cell therapy. Although CAR-T cell therapy has shown remarkable results in patients with B-NHL, the outcomes of patients with B-NHL were inferior to patients with acute lymphoblastic leukemia. The inferior response rate may be associated with physical barrier of lymphoma, tumor microenvironment and low quality of CAR-T cells manufactured from B-NHL patients. Besides, some patients relapsed after anti-CD19 CAR-T cell therapy, which possibly were due to limited CAR-T cells persistence, CD19 antigen escape or antigen down-regulation. Quite a few new antigen-targeted CAR-T products and new-generation CAR-T, for example, CD20-targeted CAR-T, CD79b-targeted CAR-T, CD37-targeted CAR-T, multi-antigen-targeted CAR-T, armored CAR-T and four-generation CAR-T are developing rapidly to figure out these deficiencies.

Genetic engineering of T cells for immunotherapy

Genetically engineered T cell immunotherapies have provided remarkable clinical success to treat B cell acute lymphoblastic leukaemia by harnessing a patient's own T cells to kill cancer, and these approaches have the potential to provide therapeutic benefit for numerous other cancers, infectious diseases and autoimmunity. By introduction of either a transgenic T cell receptor or a chimeric antigen receptor, T cells can be programmed to target cancer cells. However, initial studies have made it clear that the field will need to implement more complex levels of genetic regulation of engineered T cells to ensure both safety and efficacy. Here, we review the principles by which our knowledge of genetics and genome engineering will drive the next generation of adoptive T cell therapies.

Endothelial, pericyte and tumor cell expression in glioblastoma identifies fibroblast activation protein (FAP) as an excellent target for immunotherapy

Objectives

Targeted immunotherapies such as chimeric antigen receptor (CAR)-T cells are emerging as attractive treatment options for glioblastoma, but rely on identification of a suitable tumor antigen. We validated a new target antigen for glioblastoma, fibroblast activation protein (FAP), by undertaking a detailed expression study of human samples.

Methods

Glioblastoma and normal tissues were assessed using immunostaining, supported by analyses of published transcriptomic datasets. Short-term cultures of glioma neural stem (GNS) cells were compared to cultures of healthy astrocytes and neurons using flow cytometry. Glioblastoma tissues were dissociated and analysed by high-parameter flow cytometry and single-cell transcriptomics (scRNAseq).

Results

Compared to normal brain, FAP was overexpressed at the gene and protein level in a large percentage of glioblastoma tissues, with highest levels of expression associated with poorer prognosis. FAP was also overexpressed in several paediatric brain cancers. FAP was commonly expressed by cultured GNS cells but absent from normal neurons and astrocytes. Within glioblastoma tissues, the strongest expression of FAP was around blood vessels. In fact, almost every tumor vessel was highlighted by FAP expression, whereas normal tissue vessels and cultured endothelial cells (ECs) lacked expression. Single-cell analyses of dissociated tumors facilitated a detailed characterisation of the main cellular components of the glioblastoma microenvironment and revealed that vessel-localised FAP is because of expression on both ECs and pericytes.

Conclusion

Fibroblast activation protein is expressed by multiple cell types within glioblastoma, highlighting it as an ideal immunotherapy antigen to target destruction of both tumor cells and their supporting vascular network.

Versatile chimeric antigen receptor platform for controllable and combinatorial T cell therapy

Chimeric antigen receptor (CAR) T cells show remarkable therapeutic effects in some hematological malignancies. However, CAR T cells can also cause life-threatening side effects. In order to minimize off-target and on-target/off-tumor reactions, improve safety, enable controllability, provide high flexibility, and increase tumor specificity, we established a novel humanized artificial receptor platform termed RevCARs. RevCAR genes encode for small surface receptors lacking any antigen-binding moiety. Steering of RevCAR T cells occurs via bispecific targeting molecules (TMs). The small size of RevCAR-encoding genes allows the construction of polycistronic vectors. Here, we demonstrate that RevCAR T cells efficiently kill tumor cells, can be steered by TMs, flexibly redirected against multiple targets, and used for combinatorial targeting following the "OR" and "AND" gate logic.

Engineering T Cells to Treat Cancer: The Convergence of Immuno-Oncology and Synthetic Biology

T cells engineered to recognize and kill tumor cells have emerged as powerful agents for combating cancer. Nonetheless, our ability to engineer T cells remains relatively primitive. Aside from CAR T cells for treating B cell malignancies, most T cell therapies are risky, toxic, and often ineffective, especially those that target solid cancers. To fulfill the promise of cell-based therapies, we must transform cell engineering into a systematic and predictable science by applying the principles and tools of synthetic biology. Synthetic biology uses a hierarchical approach—assembling sets of modular molecular parts that can be combined into larger circuits and systems that perform defined target tasks. We outline the toolkit of synthetic modules that are needed to overcome the challenges of solid cancers, progress in building these components, and how these modules could be used to reliably engineer more effective and precise T cell therapies.

Chimeric antigen receptor T cells in solid tumors: a war against the tumor microenvironment

Chimeric antigen receptor (CAR) T cell is a novel approach, which utilizes anti-tumor immunity for cancer treatment. As compared to the traditional cell-mediated immunity, CAR-T possesses the improved specificity of tumor antigens and independent cytotoxicity from major histocompatibility complex molecules through a monoclonal antibody in addition to the T-cell receptor. CAR-T cell has proven its effectiveness, primarily in hematological malignancies, specifically where the CD 19 CAR-T cells were used to treat B-cell acute lymphoblastic leukemia and B-cell lymphomas. Nevertheless, there is little progress in the treatment of solid tumors despite the fact that many CAR agents have been created to target tumor antigens such as CEA, EGFR/EGFRvIII, GD2, HER2, MSLN, MUC1, and other antigens. The main obstruction against the progress of research in solid tumors is the tumor microenvironment, in which several elements, such as poor locating ability, immunosuppressive cells, cytokines, chemokines, immunosuppressive checkpoints, inhibitory metabolic factors, tumor antigen loss, and antigen heterogeneity, could affect the potency of CAR-T cells. To overcome these hurdles, researchers have reconstructed the CAR-T cells in various ways. The purpose of this review is to summarize the current research in this field, analyze the mechanisms of the major barriers mentioned above, outline the main solutions, and discuss the outlook of this novel immunotherapeutic modality.

Chimeric Antigen Receptor-Engineered T-Cells - A New Way and Era for Lymphoma Treatment

BACKGROUND

Patients with refractory or relapsed diffuse large B-cell lymphoma have a poor prognosis with the current standard of care.

OBJECTIVE

Chimeric Antigen Receptor T-cells (CAR T-cells) are functionally reprogrammed lymphocytes, which are able to recognize and kill tumor cells. The aim of this study is to make progress in this area.

METHODS

A mini-review was achieved using the articles published in Web of Science and PubMed in the last year and the new patents were made in this field.

RESULTS

The responses to CAR T-cell products axicabtagene ciloleucel and tisagenlecleucel are promising; the objective response rate can reach up to 83%, and the complete response rate ranges between 40 and 58%. About half of the patients may have serious side effects, such as cytokine release syndrome and neurotoxicity. Current and future developments include the improvement of CAR T-cell expansion and polyfunctionality, the combined use of CAR T-cells with a fusion protein between interferon and an anti-CD20 monoclonal antibody, with checkpoint inhibitors or small molecule sensitizers that have apoptotic-regulatory effects. Furthermore, the use of IL-12-expressing CAR T-cells, an improved technology for the production of CAR T-cells based on targeted nucleases, the widespread use of allogeneic CAR T-cells or universal CAR T-cells obtained from genetically engineered healthy donor T-cells are future developments actively considered.

CONCLUSION

CAR T-cell therapy significantly improved the outcome of patients with relapsed or refractory diffuse large B-cell lymphoma. The advances in CAR T-cells production technology will improve the results and enable the expansion of this new immunotherapy.

Anti-CAR-engineered T cells for epitope-based elimination of autologous CAR T cells

Although CAR T-cell therapy has demonstrated tremendous clinical efficacy especially in hematological malignancies, severe treatment-associated toxicities still compromise the widespread application of this innovative technology. Therefore, developing novel approaches to abrogate CAR T-cell-mediated side effects is of great relevance. Several promising strategies pursue the selective antibody-based depletion of adoptively transferred T cells via elimination markers. However, given the limited half-life and tissue penetration, dependence on the patients’ immune system and on-target/off-side effects of proposed monoclonal antibodies, we sought to exploit αCAR-engineered T cells to efficiently eliminate CAR T cells. For comprehensive and specific recognition, a small peptide epitope (E-tag) was incorporated into the extracellular spacer region of CAR constructs. We provide first proof-of-concept for targeting this epitope by αE-tag CAR T cells, allowing an effective killing of autologous E-tagged CAR T cells both in vitro and in vivo whilst sparing cells lacking the E-tag. In addition to CAR T-cell cytotoxicity, the αE-tag-specific T cells can be empowered with cancer-fighting ability in case of relapse, hence, have versatile utility. Our proposed methodology can most probably be implemented in CAR T-cell therapies regardless of the targeted tumor antigen aiding in improving overall safety and survival control of highly potent gene-modified cells.

Bispecific T-Cell Redirection versus Chimeric Antigen Receptor (CAR)-T Cells as Approaches to Kill Cancer Cells

The concepts for T-cell redirecting bispecific antibodies (TRBAs) and chimeric antigen receptor (CAR)-T cells are both at least 30 years old but both platforms are just now coming into age. Two TRBAs and two CAR-T cell products have been approved by major regulatory agencies within the last ten years for the treatment of hematological cancers and an additional 53 TRBAs and 246 CAR cell constructs are in clinical trials today. Two major groups of TRBAs include small, short-half-life bispecific antibodies that include bispecific T-cell engagers (BiTE®s) which require continuous dosing and larger, mostly IgG-like bispecific antibodies with extended pharmacokinetics that can be dosed infrequently. Most CAR-T cells today are autologous, although significant strides are being made to develop off-the-shelf, allogeneic CAR-based products. CAR-Ts form a cytolytic synapse with target cells that is very different from the classical immune synapse both physically and mechanistically, whereas the TRBA-induced synapse is similar to the classic immune synapse. Both TRBAs and CAR-T cells are highly efficacious in clinical trials but both also present safety concerns, particularly with cytokine release syndrome and neurotoxicity. New formats and dosing paradigms for TRBAs and CAR-T cells are being developed in efforts to maximize efficacy and minimize toxicity, as well as to optimize use with both solid and hematologic tumors, both of which present significant challenges such as target heterogeneity and the immunosuppressive tumor microenvironment.

A long way to the battlefront: CAR T cell therapy against solid cancers

Chimeric antigen receptors (CARs) are engineered synthetic receptors that redirect and reprogram T cells to tumor surface antigens for subsequent eradication. The unprecedented efficacy of CD19-CAR T cells against B-cell malignancies has inspired oncologists to extend these efforts for the treatment of solid tumors. However, limited success has been achieved so far, partially due to some of the formidable challenges, e.g. suppression of full activation, inhibition of T cell localization, lacking of ideal targets, inefficient trafficking and infiltration, immunosuppression of microenvironment, and the probability of off targets and associated side effects. Significant progresses have being made recently. Thus, an updated summary is urgently needed. Here in this review, we discuss the advantages and some of the key hurdles encountered by CAR T cell therapy in solid tumors as well as the strategies adopted to improve therapeutic outcomes of this approach. Continuing efforts to increase therapeutic potential and decrease the adverse effects of adaptive cell transfer are suggested as well.

Clinical chimeric antigen receptor-T cell therapy: a new and promising treatment modality for glioblastoma

Chimeric antigen receptor (CAR)-T cell therapy is now approved in the United States and Europe as a standard treatment for relapsed/refractory B-cell malignancies. It has also been approved recently by the Therapeutic Goods Administration in Australia and may soon be publicly reimbursed. This advance has accentuated scientific, clinical and commercial interest in adapting this exciting technology for the treatment of solid cancers where it is widely recognised that the challenges of overcoming a hostile tumor microenvironment are most acute. Indeed, CAR-T cell technology may be of the greatest value for those cancers that lack pre-existing immunity because they are immunologically 'cold', or have a low somatic tumor mutation load, or both. These cancers are generally not amenable to therapeutic immune checkpoint blockade, but CAR-T cell therapy may be effective because it provides an abundant supply of autologous tumor-specific T cells. This is achieved by using genetic engineering to re-direct autologous T-cell cytotoxicity towards a tumor-associated antigen, bypassing endogenous T-cell requirements for antigen processing, MHC-dependent antigen presentation and co-stimulation. One of the most challenging solid cancers is glioblastoma, which has among the least permissive immunological milieu of any cancer, and which is almost always fatal. Here, we argue that CAR-T cell technology may counter some glioblastoma defences and provide a beachhead for furthering our eventual therapeutic aims of restoring effective antitumor immunity. Although clinical investigation of CAR-T cell therapy for glioblastoma is at an early stage, we discuss three recently published studies, which feature significant differences in target antigen, CAR-T cell phenotype, route of administration and tumor response. We discuss the lessons, which may be learned from these studies and which may guide further progress in the field.