Strategies to Circumvent the Side-Effects of Immunotherapy Using Allogeneic CAR-T Cells and Boost Its Efficacy: Results of Recent Clinical Trials

Potential alternatives to αβ-T cells to prevent graft-versus-host disease (GvHD) in allogeneic chimeric antigen receptor (CAR)-based cancer immunotherapy: A comprehensive review

Currently, CAR-T cell therapy relies on an individualized manufacturing process in which patient's own T cells are infused back into patients after being engineered and expanded ex vivo. Despite the astonishing outcomes of autologous CAR-T cell therapy, this approach is endowed with several limitations and drawbacks, such as high cost and time-consuming manufacturing process. Switching the armature of CAR-T cell therapy from autologous settings to allogeneic can overcome several bottlenecks of the current approach. Nevertheless, the use of allogeneic CAR-T cells is limited by the risk of life-threatening GvHD. Thus, in recent years, developing a method to move CAR-T cell therapy to allogeneic settings without the risk of GvHD has become a hot research topic in this field. Since the alloreactivity of αβ T-cell receptor (TCR) accounts for developing GvHD, several efforts have been made to disrupt endogenous TCR of allogeneic CAR-T cells using gene editing tools to prevent GvHD. Nonetheless, the off-target activity of gene editing tools and their associated genotoxicities, as well as the negative consequences of endogenous TCR disruption, are the main concerns of using this approach. As an alternative, CAR αβ-T cells can be replaced with other types of CAR-engineered cells that are capable of recognizing and killing malignant cells through CAR while avoiding the induction of GvHD. These alternatives include T cell subsets with restricted TCR repertoire (γδ-T, iNKT, virus-specific T, double negative T cells, and MAIT cells), killer cells (NK and CIK cells), non-lymphocytic cells (neutrophils and macrophages), stem/progenitor cells, and cell-free extracellular vesicles. In this review, we discuss how these alternatives can move CAR-based immunotherapy to allogeneic settings to overcome the bottlenecks of autologous manner without the risk of GvHD. We comprehensively discuss the pros and cons of these alternatives over the traditional CAR αβ-T cells in light of their preclinical studies and clinical trials.

RNA technology and nanocarriers empowering in vivo chimeric antigen receptor therapy

The remarkable success of mRNA-based coronavirus 2019 (COVID-19) vaccines has propelled the advancement of nanomedicine, specifically in the realm of RNA technology and nanomaterial delivery systems. Notably, significant strides have been made in the development of RNA-based in vivo chimeric antigen receptor (CAR) therapy. In comparison to the conventional ex vivo CAR therapy, in vivo CAR therapy offers several benefits including simplified preparation, reduced costs, broad applicability and decreased potential for carcinogenic effects. This review summarises the RNA-based CAR constructs in in vivo CAR therapy, discusses the current applications of in vivo delivery vectors and outlines the immune cells edited with CAR molecules. We aim for the conveyed messages to contribute towards the advancement of in vivo CAR application.

Overexpression of an Engineered SERPINB9 Enhances Allogeneic T-cell Persistence and Efficacy

Allogeneic chimeric antigen receptor (CAR)-expressing T cells offer many advantages over autologous therapies, but their benefits are curtailed by graft-versus-host disease and elimination by recipient immune cells. Moreover, just as with autologous therapies, allogeneic CAR T cells are susceptible to activation-induced cell death (AICD) caused by chronic antigen exposure (CAE). Granzyme B- and Fas/Fas ligand-initiated caspase-mediated apoptoses are key mechanisms of T-cell death caused by T/NK cell-mediated allorejection or CAE. We explored a protective strategy of engineering CAR T cells to overexpress variants of the Granzyme B-specific serine protease inhibitor SERPINB9 (SB9) to improve allogeneic T-cell persistence and antitumor efficacy. We showed that the overexpression of an SB9 variant with broadened caspase specificity, SB9(CAS), not only significantly reduced rejection of allogeneic CAR T cells but also increased their resistance to AICD and enabled them to thrive better under CAE, thus improving allogeneic T-cell persistence and antitumor activity in vitro and in vivo. In addition, although SB9(CAS) overexpression improved the efficacy of allogeneic CAR T-cell therapy by conferring protection to cell death, we did not observe any autonomous growth, and the engineered CAR T cells were still susceptible to an inducible suicide switch. Hence, SB9(CAS) overexpression is a promising strategy that can strengthen current development of cell therapies, broadening their applications to address unmet medical needs.

The paths toward non-viral CAR-T cell manufacturing: A comprehensive review of state-of-the-art methods

Although CAR-T cell therapy has emerged as a game-changer in cancer immunotherapy several bottlenecks limit its widespread use as a front-line therapy. Current protocols for the production of CAR-T cells rely mainly on the use of lentiviral/retroviral vectors. Nevertheless, according to the safety concerns around the use of viral vectors, there are several regulatory hurdles to their clinical use. Large-scale production of viral vectors under "Current Good Manufacturing Practice" (cGMP) involves rigorous quality control assessments and regulatory requirements that impose exorbitant costs on suppliers and as a result, lead to a significant increase in the cost of treatment. Pursuing an efficient non-viral method for genetic modification of immune cells is a hot topic in cell-based gene therapy. This study aims to investigate the current state-of-the-art in non-viral methods of CAR-T cell manufacturing. In the first part of this study, after reviewing the advantages and disadvantages of the clinical use of viral vectors, different non-viral vectors and the path of their clinical translation are discussed. These vectors include transposons (sleeping beauty, piggyBac, Tol2, and Tc Buster), programmable nucleases (ZFNs, TALENs, and CRISPR/Cas9), mRNA, plasmids, minicircles, and nanoplasmids. Afterward, various methods for efficient delivery of non-viral vectors into the cells are reviewed.

Advances in CAR-NK cell therapy for hematological malignancies

Chimeric antigen receptor T (CAR-T) cell therapy has revolutionized the treatment of hematological malignancies, demonstrably improving patient outcomes and prognosis. However, its application has introduced new challenges, such as safety concerns, off-target toxicities, and significant costs. Natural killer (NK) cells are crucial components of the innate immune system, capable of eliminating tumor cells without prior exposure to specific antigens or pre-activation. This inherent advantage complements the limitations of T cells, making CAR-NK cell therapy a promising avenue for hematological tumor immunotherapy. In recent years, preclinical and clinical studies have yielded preliminary evidence supporting the safety and efficacy of CAR-NK cell therapy in hematological malignancies, paving the way for future advancements in immunotherapy. This review aims to succinctly discuss the characteristics, significant therapeutic progress, and potential challenges associated with CAR-NK cell therapy.

Progress and pitfalls of gene editing technology in CAR-T cell therapy: a state-of-the-art review

CAR-T cell therapy has shown remarkable promise in treating B-cell malignancies, which has sparked optimism about its potential to treat other types of cancer as well. Nevertheless, the Expectations of CAR-T cell therapy in solid tumors and non-B cell hematologic malignancies have not been met. Furthermore, safety concerns regarding the use of viral vectors and the current personalized production process are other bottlenecks that limit its widespread use. In recent years the use of gene editing technology in CAR-T cell therapy has opened a new way to unleash the latent potentials of CAR-T cell therapy and lessen its associated challenges. Moreover, gene editing tools have paved the way to manufacturing CAR-T cells in a fully non-viral approach as well as providing a universal, off-the-shelf product. Despite all the advantages of gene editing strategies, the off-target activity of classical gene editing tools (ZFNs, TALENs, and CRISPR/Cas9) remains a major concern. Accordingly, several efforts have been made in recent years to reduce their off-target activity and genotoxicity, leading to the introduction of advanced gene editing tools with an improved safety profile. In this review, we begin by examining advanced gene editing tools, providing an overview of how these technologies are currently being applied in clinical trials of CAR-T cell therapies. Following this, we explore various gene editing strategies aimed at enhancing the safety and efficacy of CAR-T cell therapy.

Advances and challenges in gene therapy strategies for pediatric cancer: a comprehensive update

Pediatric cancers represent a tragic but also promising area for gene therapy. Although conventional treatments have improved survival rates, there is still a need for targeted and less toxic interventions. This article critically analyzes recent advances in gene therapy for pediatric malignancies and discusses the challenges that remain. We explore the innovative vectors and delivery systems that have emerged, such as adeno-associated viruses and non-viral platforms, which show promise in addressing the unique pathophysiology of pediatric tumors. Specifically, we examine the field of chimeric antigen receptor (CAR) T-cell therapies and their adaptation for solid tumors, which historically have been more challenging to treat than hematologic malignancies. We also discuss the genetic and epigenetic complexities inherent to pediatric cancers, such as tumor heterogeneity and the dynamic tumor microenvironment, which pose significant hurdles for gene therapy. Ethical considerations specific to pediatric populations, including consent and long-term follow-up, are also analyzed. Additionally, we scrutinize the translation of research from preclinical models that often fail to mimic pediatric cancer biology to the regulatory landscapes that can either support or hinder innovation. In summary, this article provides an up-to-date overview of gene therapy in pediatric oncology, highlighting both the rapid scientific progress and the substantial obstacles that need to be addressed. Through this lens, we propose a roadmap for future research that prioritizes the safety, efficacy, and complex ethical considerations involved in treating pediatric patients. Our ultimate goal is to move from incremental advancements to transformative therapies.

The paths and challenges of "off-the-shelf" CAR-T cell therapy: An overview of clinical trials

The advent of chimeric antigen receptor T cells (CAR-T cells) has made a tremendous revolution in the era of cancer immunotherapy, so that since 2017 eight CAR-T cell products have been granted marketing authorization. All of these approved products are generated from autologous sources, but this strategy faces several challenges such as time-consuming and expensive manufacturing process and reduced anti-tumor potency of patients' T cells due to the disease or previous therapies. The use of an allogeneic source can overcome these issues and provide an industrial, scalable, and standardized manufacturing process that reduces costs and provides faster treatment for patients. Nevertheless, for using allogeneic CAR-T cells, we are faced with the challenge of overcoming two formidable impediments: severe life-threatening graft-versus-host-disease (GvHD) caused by allogeneic CAR-T cells, and allorejection of allogeneic CAR-T cells by host immune cells which is called "host versus graft" (HvG). In this study, we reviewed recent registered clinical trials of allogeneic CAR-T cell therapy to analyze different approaches to achieve a safe and efficacious "off-the-shelf" source for chimeric antigen receptor (CAR) based immunotherapy.

Case Report: Unedited allogeneic chimeric antigen receptor T cell bridging to conditioning-free hematopoietic stem cell transplantation for a child with refractory Burkitt lymphoma

Purpose

Burkitt lymphoma (BL) is the most common tumor of non-Hodgkin's lymphoma (NHL) in children, accounting for about 40% of cases. Although different combined short-course chemotherapies have achieved a good effect, refractory/relapsed BL has a poor prognosis with cure rates less than 30%. Chimeric antigen receptor T cell (CAR-T) therapy has developed rapidly in recent years and achieved excellent results in acute lymphoblastic leukemia (ALL). However, in some cases, there is a failure to produce autologous CAR-T cells because of T-cell dysfunction. In such cases, allogeneic CAR-T therapy has to be considered.

Methods

A 17-year-old boy with stage II BL did not respond to extensive chemotherapy and sequential autologous CAR-T therapy. Lentiviral vectors containing anti-CD20-BB-ζ (20CAR) and anti-CD22-BB-ζ (22CAR) transgenes were used to modify the T cells from an HLA-identical matched unrelated donor. Flow cytometry was used to assess the cytokine analyses and CAR-T cell persistence in peripheral blood, enumerated by qPCR as copies per ug DNA. Informed consent for autologous/allogeneic CAR-T therapy was obtained from the patient and his legal guardian.

Results

Unedited HLA-matched allogeneic CD20 and CD22 CAR-T cells were infused after lymphodepletion chemotherapy with cyclophosphamide and fludarabine. The patient experienced Grade IV cytokine release syndrome (CRS) and went into complete remission (CR) after anti-inflammatory treatment including tocilizumab. Because of persistent pancytopenia and full donor chimerism, the same donor's conditioning-free peripheral blood stem cells were successfully transplanted 55 days post CAR-T. Neutrophils were engrafted at day +11 and platelets were rebuilt at day +47 without obvious acute graft-versus-host disease (GVHD), but there was mild chronic GVHD in the skin and eyes. Currently, active anti-rejection therapy is still underway.

Conclusion

Unedited HLA-matched allogeneic CAR-T cell therapy could be an innovative, effective, and safe treatment for children with refractory/relapse BL without obvious acute GVHD. Conditioning-free allogeneic hematopoietic stem cell transplantation (HSCT) from the same donor is feasible for a patient with full donor T-cell chimerism after allogeneic CAR-T. It cannot be ignored that close GVHD monitoring is needed post HSCT.

New cell sources for CAR-based immunotherapy

Chimeric antigen receptor (CAR) T cell therapy, in which a patient's own T lymphocytes are engineered to recognize and kill cancer cells, has achieved striking success in some hematological malignancies in preclinical and clinical trials, resulting in six FDA-approved CAR-T products currently available in the market. Despite impressive clinical outcomes, concerns about treatment failure associated with low efficacy or high cytotoxicity of CAR-T cells remain. While the main focus has been on improving CAR-T cells, exploring alternative cellular sources for CAR generation has garnered growing interest. In the current review, we comprehensively evaluated other cell sources rather than conventional T cells for CAR generation.

Genetic engineering strategies to enhance antitumor reactivity and reduce alloreactivity for allogeneic cell-based cancer therapy

The realm of cell-based immunotherapy holds untapped potential for the development of next-generation cancer treatment through genetic engineering of chimeric antigen receptor (CAR)-engineered T (CAR-T) cell therapies for targeted eradication of cancerous malignancies. Such allogeneic "off-the-shelf" cell products can be advantageously manufactured in large quantities, stored for extended periods, and easily distributed to treat an exponential number of cancer patients. At current, patient risk of graft-versus-host disease (GvHD) and host-versus-graft (HvG) allorejection severely restrict the development of allogeneic CAR-T cell products. To address these limitations, a variety of genetic engineering strategies have been implemented to enhance antitumor efficacy, reduce GvHD and HvG onset, and improve the overall safety profile of T-cell based immunotherapies. In this review, we summarize these genetic engineering strategies and discuss the challenges and prospects these approaches provide to expedite progression of translational and clinical studies for adoption of a universal cell-based cancer immunotherapy.

Emerging frontiers in immuno- and gene therapy for cancer

BACKGROUND AIMS

The field of cell and gene therapy in oncology has moved rapidly since 2017 when the first cell and gene therapies, Kymriah followed by Yescarta, were approved by the Food and Drug Administration in the United States, followed by multiple other countries. Since those approvals, several new products have gone on to receive approval for additional indications. Meanwhile, efforts have been made to target different cancers, improve the logistics of delivery and reduce the cost associated with novel cell and gene therapies. Here, we highlight various cell and gene therapy-related technologies and advances that provide insight into how these new technologies will speed the translation of these therapies into the clinic.

CONCLUSIONS

In this review, we provide a broad overview of the current state of cell and gene therapy-based approaches for cancer treatment - discussing various effector cell types and their sources, recent advances in both CAR and non-CAR genetic modifications, and highlighting a few promising approaches for increasing in vivo efficacy and persistence of therapeutic drug products.

Efficacy and safety of universal (TCRKO) ARI-0001 CAR-T cells for the treatment of B-cell lymphoma

Autologous T cells expressing the Chimeric Antigen Receptor (CAR) have been approved as advanced therapy medicinal products (ATMPs) against several hematological malignancies. However, the generation of patient-specific CAR-T products delays treatment and precludes standardization. Allogeneic off-the-shelf CAR-T cells are an alternative to simplify this complex and time-consuming process. Here we investigated safety and efficacy of knocking out the TCR molecule in ARI-0001 CAR-T cells, a second generation αCD19 CAR approved by the Spanish Agency of Medicines and Medical Devices (AEMPS) under the Hospital Exemption for treatment of patients older than 25 years with Relapsed/Refractory acute B cell lymphoblastic leukemia (B-ALL). We first analyzed the efficacy and safety issues that arise during disruption of the TCR gene using CRISPR/Cas9. We have shown that edition of TRAC locus in T cells using CRISPR as ribonuleorproteins allows a highly efficient TCR disruption (over 80%) without significant alterations on T cells phenotype and with an increased percentage of energetic mitochondria. However, we also found that efficient TCRKO can lead to on-target large and medium size deletions, indicating a potential safety risk of this procedure that needs monitoring. Importantly, TCR edition of ARI-0001 efficiently prevented allogeneic responses and did not detectably alter their phenotype, while maintaining a similar anti-tumor activity ex vivo and in vivo compared to unedited ARI-0001 CAR-T cells. In summary, we showed here that, although there are still some risks of genotoxicity due to genome editing, disruption of the TCR is a feasible strategy for the generation of functional allogeneic ARI-0001 CAR-T cells. We propose to further validate this protocol for the treatment of patients that do not fit the requirements for standard autologous CAR-T cells administration.

Progress on methods of T lymphocyte development in vitro

T lymphocytes (T cells) play an important role in adoptive cellular immunotherapy (ACT). T cells can be stably derived and easily obtained by various methods of T cell development in vitro, which have more advantages than traditional methods of T cells isolated from autologous or allogeneic tissues. At present, there are mainly three methods for T cell development in vitro: fetal thymus organ culture, recombinant thymus organ culture and two-dimensional culture driven by Notch signal. Fetal thymus organ culture is easy to operate, the isolated thymus can support T cell differentiation and development to maturity in vitro, but the intact thymus has problems of limited maintenance time and difficulty in cell harvesting. In recombinant thymic organ culture, various thymic stromal cells are dispersed and recombined to construct a three-dimensional culture environment, which can support T cell maturation in vitro and in vivo; however, biomaterials and three-dimensional environment may lead to limited culture maintenance time and cell yield. Two-dimensional culture method uses artificial presentation of Notch signaling pathway ligands to drive T cell differentiation and development; the culture architecture is simple and stable, but it can only support T cell development to the early immature stage. This article reviews the research progress of various culture methods of T cell development in vitro, and discusses the existing problems and the future development to facilitate the application of ACT.

How Should the Worldwide Knowledge of Traditional Cancer Healing Be Integrated with Herbs and Mushrooms into Modern Molecular Pharmacology?

Traditional herbal medicine (THM) is a "core" from which modern medicine has evolved over time. Besides this, one third of people worldwide have no access to modern medicine and rely only on traditional medicine. To date, drugs of plant origin, or their derivates (paclitaxel, vinblastine, vincristine, vinorelbine, etoposide, camptothecin, topotecan, irinotecan, and omacetaxine), are very important in the therapy of malignancies and they are included in most chemotherapeutic regimes. To date, 391,000 plant and 14,000 mushroom species exist. Their medical and biochemical capabilities have not been studied in detail. In this review, we systematized the information about plants and mushrooms, as well as their active compounds with antitumor properties. Plants and mushrooms are divided based on the regions where they are used in ethnomedicine to treat malignancies. The majority of their active compounds with antineoplastic properties and mechanisms of action are described. Furthermore, on the basis of the available information, we divided them into two priority groups for research and for their potential of use in antitumor therapy. As there are many prerequisites and some examples how THM helps and strengthens modern medicine, finally, we discuss the positive points of THM and the management required to transform and integrate THM into the modern medicine practice.

Precision Medicine: In Vivo CAR Therapy as a Showcase for Receptor-Targeted Vector Platforms

Chimeric antigen receptor (CAR) T cells are a cancer immunotherapy of extremes: Unprecedentedly effective, but complex and costly to manufacture, they are not yet a therapeutic option for all who would benefit. This disparity has motivated worldwide efforts to simplify treatment. Among the proposed solutions, the generation of CAR T cells directly in the patient, i.e. in vivo, is arguably simultaneously the most technically challenging and clinically useful approach to convert CAR therapy from a cell-based autologous medicinal product into a universally applicable off-the-shelf treatment. Here we review the current state-of-the-art of in vivo CAR therapy, focusing especially on the vector technologies used. These cover lentiviral vectors, adenovirus-associated vectors as well as synthetic polymer nanocarriers and lipid nanoparticles. Proof-of-concept, i.e. the generation of CAR cells directly in mouse models, has been demonstrated for all vector platforms. Receptor-targeting of vector particles is crucial, as it can prevent CAR gene delivery into off-target cells, thus reducing toxicities. We discuss the properties of the vector platforms, such as their immunogenicity, potency, and modes of CAR delivery (permanent versus transient). Finally, we outline the work required to advance in vivo CAR therapy from proof-of-concept to a robust, scalable technology for clinical testing.