CARs: Beyond T Cells and T Cell-Derived Signaling Domains

Engineering macrophages and their derivatives: A new hope for antitumor therapy

Macrophages are central to the immune system and are found in nearly all tissues. Recently, the development of therapies based on macrophages has attracted significant interest. These therapies utilize macrophages' key roles in immunity, their ability to navigate biological barriers, and their tendency to accumulate in tumors. This review explores the advancement of macrophage-based treatments. We discuss the bioengineering of macrophages for improved anti-tumor effects, the use of CAR macrophage therapy for targeting cancer cells, and macrophages as vehicles for therapeutic delivery. Additionally, we examine engineered macrophage products, like extracellular vesicles and membrane-coated nanoparticles, for their potential in precise and less toxic tumor therapy. Challenges in moving these therapies from research to clinical practice are also highlighted. The aim is to succinctly summarize the current status, challenges, and future directions of engineered macrophages in cancer therapy.

CAR-NK cell therapy in AML: Current treatment, challenges, and advantage

Over the last decade, discovery of novel therapeutic method has been attention by the researchers and has changed the therapeutic perspective of hematological malignancies. Although NK cell play a pivotal role in the elimination of abnormal and cancerous cells, there are evidence that NK cell are disarm in hematological malignancy. Chimeric antigen receptor NK (CAR-NK) cell therapy, which includes the engineering of NK cells to detect tumor-specific antigens and, as a result, clear of cancerous cells, has created various clinical advantage for several human malignancies treatment. In the current review, we summarized NK cell dysfunction and CAR-NK cell based immunotherapy to treat AML patient.

Engineered CD147-CAR macrophages for enhanced phagocytosis of cancers

Chimeric antigen receptor (CAR) T cell therapy has shown promising results in hematologic malignancies, but its effectiveness in solid cancers remains challenging. Macrophages are immune cells residing within the tumor microenvironment. They can phagocytose tumor cells. Recently, CAR macrophages (CAR-M) have been a promising candidate for treating solid cancers. One of the common cancer antigens overexpressed in various types of cancer is CD147. CAR-T and NK cells targeting CD147 antigen have shown significant efficacy against hepatocellular carcinoma. Nevertheless, CAR-M targeting the CD147 molecule has not been investigated. In this study, we generated CAR targeting the CD147 molecule using the THP-1 monocytic cell line (CD147 CAR-M). The CD147 CAR-M exhibited typical macrophage characteristics, including phagocytosis of zymosan bioparticles and polarization ability toward M1 and M2 phenotypes. Furthermore, the CD147 CAR-M demonstrated enhanced anti-tumor activity against K562 and MDA-MB-231 cells without exhibiting off-target cytotoxicity against normal cells. Our research provides valuable insights into the potential of CD147 CAR-M as a promising platform for cancer immunotherapy, with applications in both hematologic malignancies and solid cancers.

Nanobody-based CAR NK cells for possible immunotherapy of MICA+ tumors

The glycoproteins MICA and MICB are upregulated on the surface of cells undergoing stress, for instance due to (viral) infection or malignant transformation. MICA/B are the ligands for the activating receptor NKG2D, found on cytotoxic immune cells like NK cells, CD8+ T cells, and γδ T cells. Upon engagement of NKG2D, these cells are activated to eradicate the MICA/B-positive targets, assisted by the secretion of cytokines. Nanobodies, or VHHs, are derived from the variable regions of camelid heavy-chain only immunoglobulins. Nanobodies are characterized by their small size, ease of production, stability, and specificity of recognition. We generated nanobodies that recognize membrane-bound MICA with high affinity. Here, we use these nanobodies as building blocks for a chimeric antigen receptor (CAR) to establish VHH-based CAR NK cells. These anti-MICA nanobody-based CAR NK cells recognize and selectively kill MICA-positive tumor cells in vitro and in vivo. We track localization of the VHH-based CAR NK cells to MICA-positive lung metastases by immuno-positron emission tomography imaging.

Electroporation of mRNA as a Universal Technology Platform to Transfect a Variety of Primary Cells with Antigens and Functional Proteins

Electroporation (EP) of mRNA into human cells is a broadly applicable method to transiently express proteins of choice in a variety of different cell types. We have spent more than two decades to optimize and adapt this method, first for antigen-loading of dendritic cells (DCs) and subsequently for T cells, B cells, bulk PBMCs, and several cell lines. In this regard, antigens were introduced, processed, and presented in context of MHC class I and II. Next to that, functional proteins like adhesion receptors, T-cell receptors (TCRs), chimeric antigen receptors (CARs), constitutively active signal transducers (i.e. caIKK), and others were successfully expressed. We have also established this protocol under full GMP compliance as part of a manufacturing license to produce mRNA-electroporated DCs and mRNA-electroporated T cells for therapeutic applications in clinical trials. Therefore, we here want to share our universal mRNA electroporation protocol and the experience we have gathered with this method. The advantages of the transfection method presented here are: (1) easy adaptation to different cell types; (2) scalability from 106 to approximately 108 cells per shot; (3) high transfection efficiency (80-99%); (4) homogenous protein expression; (5) GMP compliance if the EP is performed in a class A clean room; and (6) no transgene integration into the genome. The provided protocol involves: OptiMEM® as EP medium, a square-wave pulse with 500 V, and 4 mm cuvettes. To adapt the protocol to differently sized cells, simply the pulse time has to be altered. Thus, we share an overview of proven electroporation settings (including recovery media), which we have established for various cell types. Next to the basic protocol, we also provide an extensive list of hints and tricks, which, in our opinion, are of great value for everyone who intends to use this transfection technique.

Cytokine release syndrome and cancer immunotherapies - historical challenges and promising futures

Cancer is the leading cause of death worldwide. Cancer immunotherapy involves reinvigorating the patient's own immune system to fight against cancer. While novel approaches like Chimeric Antigen Receptor (CAR) T cells, bispecific T cell engagers, and immune checkpoint inhibitors have shown promising efficacy, Cytokine Release Syndrome (CRS) is a serious adverse effect and remains a major concern. CRS is a phenomenon of immune hyperactivation that results in excessive cytokine secretion, and if left unchecked, it may lead to multi-organ failure and death. Here we review the pathophysiology of CRS, its occurrence and management in the context of cancer immunotherapy, and the screening approaches that can be used to assess CRS and de-risk drug discovery earlier in the clinical setting with more predictive pre-clinical data. Furthermore, the review also sheds light on the potential immunotherapeutic approaches that can be used to overcome CRS associated with T cell activation.

CAR-NKT cell therapy: a new promising paradigm of cancer immunotherapy

Today, cancer treatment is one of the fundamental problems facing clinicians and researchers worldwide. Efforts to find an excellent way to treat this illness continue, and new therapeutic strategies are developed quickly. Adoptive cell therapy (ACT) is a practical approach that has been emerged to improve clinical outcomes in cancer patients. In the ACT, one of the best ways to arm the immune cells against tumors is by employing chimeric antigen receptors (CARs) via genetic engineering. CAR equips cells to target specific antigens on tumor cells and selectively eradicate them. Researchers have achieved promising preclinical and clinical outcomes with different cells by using CARs. One of the potent immune cells that seems to be a good candidate for CAR-immune cell therapy is the Natural Killer-T (NKT) cell. NKT cells have multiple features that make them potent cells against tumors and would be a powerful replacement for T cells and natural killer (NK) cells. NKT cells are cytotoxic immune cells with various capabilities and no notable side effects on normal cells. The current study aimed to comprehensively provide the latest advances in CAR-NKT cell therapy for cancers.

T cells engineered with full-length NKG2D linked to signaling domains of 4-1BB and CD3ζ show enhanced antitumor activity

Since NKG2D ligands (NKG2DLs) are primarily overexpressed on multiple types of solid tumors but absent on most normal tissues, NKG2DLs could be optimal antigens for CAR-T cells. To date, there have been two types of NKG2DL CARs: (i) the extracellular domain of NKG2D fused to the CD8a transmembrane domain, signaling domains of 4-1BB and CD3ζ (NKBz) and (ii) full-length NKG2D fused to the CD3ζ signaling domain (chNKz). Although NKBz- and chNKz-engineered T cells both showed antitumor activities, a comparison of their functions has not been reported. In addition, use of the 4-1BB signaling domain into the CAR construct could prolong the persistence and resistance to antitumor activities of CAR-T cells, we designed a new NKG2DL CAR, full-length NKG2D fused to the signaling domains of 4-1BB and CD3ζ (chNKBz). Among the two types of NKG2DL CAR-T cells reported in previous studies, we found that chNKz T cells had stronger antitumor ability than NKBz T cells in vitro, but their antitumor activity in vivo is similar. The chNKBz T cells showed antitumor activity superior to that of chNKz T cells and NKBz T cells in vitro and in vivo, providing a new option for the immunotherapy of NKG2DL-positive tumor patients.

Current Situation and Prospect of Adoptive Cellular Immunotherapy for Malignancies

Adoptive cell immunotherapy (ACT) is an innovative promising treatment for tumors. ACT is characterized by the infusion of active anti-tumor immune cells (specific and non-specific) into patients to kill tumor cells either directly or indirectly by stimulating the body's immune system. The patient's (autologous) or a donor's (allogeneic) immune cells are used to improve immune function. Chimeric antigen receptor (CAR) T cells (CAR-T) is a type of ACT that has gained attention. T cells from the peripheral blood are genetically engineered to express CARs that rapidly proliferate and specifically recognize target antigens to exert its anti-tumor effects. Clinical application of CAR-T therapy for hematological tumors has shown good results, but adverse reactions and recurrence limit its applicability. Tumor infiltrating lymphocyte (TIL) therapy is effective for solid tumors. TIL therapy exhibits T cell receptor (TCR) clonality, superior tumor homing ability, and low targeted toxicity, but its successful application is limited to a number of tumors. Regardless, TIL and CAR-T therapies are effective for treating cancer. Additionally, CAR-natural killer (NK), CAR-macrophages (M), and TCR-T therapies are currently being researched. In this review, we highlight the current developments and limitations of several types of ACT.

Diverse Neutrophil Functions in Cancer and Promising Neutrophil-Based Cancer Therapies

Neutrophils represent the most abundant cell type of leukocytes in the human blood and have been considered a vital player in the innate immune system and the first line of defense against invading pathogens. Recently, several studies showed that neutrophils play an active role in the immune response during cancer development. They exhibited both pro-oncogenic and anti-tumor activities under the influence of various mediators in the tumor microenvironment. Neutrophils can be divided into several subpopulations, thus contradicting the traditional concept of neutrophils as a homogeneous population with a specific function in the innate immunity and opening new horizons for cancer therapy. Despite the promising achievements in this field, a full understanding of tumor-neutrophil interplay is currently lacking. In this review, we try to summarize the current view on neutrophil heterogeneity in cancer, discuss the different communication pathways between tumors and neutrophils, and focus on the implementation of these new findings to develop promising neutrophil-based cancer therapies.

CD19 chimeric antigen receptor T-cell therapy following autologous stem cell transplantation against relapsed or refractory Burkitt lymphoma/leukemia: A case report and literature review

Burkitt lymphoma or leukemia (BL) is a highly aggressive non-Hodgkin lymphoma. Older age (over 60 years old) and the presence of high-risk factors (such as abdominal mass, high levels of the serum lactic dehydrogenase, Ann Arbor stage II-IV and so on) usually predict a poorer outcome. Chimeric antigen receptor T cells (CART) have achieved remarkable success in the treatment of B-cell leukemia and lymphoma. Here, for the first time, we report a 61-year-old, high-risk BL patient with autologous stem cell transplantation (ASCT) bridging therapy prior to CART as consolidation therapy. Our findings demonstrate that the combination of ASCT and CART for BL is safe and feasible.

The CD8α hinge is intrinsically disordered with a dynamic exchange that includes proline cis-trans isomerization

T cells engineered to express artificial chimeric antigen receptors (CARs) that selectively target tumor-specific antigens or deleterious cell types offer transformative therapeutic possibilities. CARs contain an N-terminal extracellular antigen recognition domain, C-terminal intracellular signal transduction domains, and connecting hinge and transmembrane regions, each of which have been varied to optimize targeting and minimize toxicity. We find that a CD22-targeting CAR harboring a CD8α hinge (H) exhibits greater cytotoxicity against a low antigen density CD22⁺ leukemia as compared to an equivalent CAR with a CD28 H. We therefore studied the biophysical and dynamic properties of the CD8α H by nuclear magnetic resonance (NMR) spectroscopy. We find that a large region of the CD8α H undergoes dynamic chemical exchange between distinct and observable states. This exchanging region contains proline residues dispersed throughout the sequence that undergo cis-trans isomerization. Up to four signals of differing intensity are observed, with the most abundantly populated being intrinsically disordered and with all prolines in the trans isomerization state. The lesser populated states all contain cis prolines and evidence of local structural motifs. Altogether, our data suggest that the CD8α H lacks long-range structural order but has local structural motifs that transiently exchange with a dominant disordered state. We propose that structural plasticity and local structural motifs promoted by cis proline states within the CD8α H are important for relaying and amplifying antigen-binding effects to the transmembrane and signal transduction domains.

Emerging applications of nanobodies in cancer therapy

Cancer is a heterogeneous disease, requiring treatment tailored to the unique phenotype of the patient's tumor. Monoclonal antibodies (mAbs) and variants thereof have enabled targeted therapies to selectively target cancer cells. Cancer cell-specific mAbs have been used for image-guided surgery and targeted delivery of radionuclides or toxic agents, improving classical treatment strategies. Cancer cell-specific mAbs can further inhibit tumor cell growth or can stimulate immune-mediated destruction of cancer cells, a feature that has also been achieved through mAb-mediated manipulation of immune cells and pathways. Drawbacks of mAbs and their variants, together with the discovery of camelid heavy chain-only antibodies and the many advantageous features of their variable domains, referred to as V_HHs, single domain antibodies or nanobodies (Nbs), resulted in the exploration of Nbs as an alternative targeting moiety. We therefore review the state-of-the-art as well as novel exploitation strategies of Nbs for targeted cancer therapy.

Exciting Times for Lipid Nanoparticles: How Canadian Discoveries Are Enabling Gene Therapies

In this brief perspective, we describe key events in the history of the lipid-based nanomedicine field, highlight Canadian contributions, and outline areas where lipid nanoparticle technology is poised to have a transformative effect on the future of medicine.

Advances in NK cell production

Immunotherapy based on natural killer (NK) cells is a promising approach for treating a variety of cancers. Unlike T cells, NK cells recognize target cells via a major histocompatibility complex (MHC)-independent mechanism and, without being sensitized, kill the cells directly. Several strategies for obtaining large quantities of NK cells with high purity and high cytotoxicity have been developed. These strategies include the use of cytokine-antibody fusions, feeder cells or membrane particles to stimulate the proliferation of NK cells and enhance their cytotoxicity. Various materials, including peripheral blood mononuclear cells (PBMCs), umbilical cord blood (UCB), induced pluripotent stem cells (iPSCs) and NK cell lines, have been used as sources to generate NK cells for immunotherapy. Moreover, genetic modification technologies to improve the proliferation of NK cells have also been developed to enhance the functions of NK cells. Here, we summarize the recent advances in expansion strategies with or without genetic manipulation of NK cells derived from various cellular sources. We also discuss the closed, automated and GMP-controlled large-scale expansion systems used for NK cells and possible future NK cell-based immunotherapy products.

Current Status of CRISPR/Cas9 Application in Clinical Cancer Research: Opportunities and Challenges

Cancer is considered by not only multiple genetic but also epigenetic amendments that drive malignant cell propagation and consult chemo-resistance. The ability to correct or ablate such mutations holds enormous promise for battling cancer. Recently, because of its great efficiency and feasibility, the CRISPR-Cas9 advanced genome editing technique has been extensively considered for therapeutic investigations of cancers. Several studies have used the CRISPR-Cas9 technique for editing cancer cell genomic DNA in cells and animal cancer models and have shown therapeutic potential in intensifying anti-cancer protocols. Moreover, CRISPR-Cas9 may be used to correct oncogenic mutations, discover anticancer drugs, and engineer immune cells and oncolytic viruses for immunotherapeutic treatment of cancer. We herein discuss the challenges and opportunities for translating therapeutic methods with CRISPR-Cas9 for clinical use and suggest potential directions of the CRISPR-Cas9 system for future cancer therapy.

Imaging Primer on Chimeric Antigen Receptor T-Cell Therapy for Radiologists

Chimeric antigen receptor (CAR) T-cell therapy is a recently approved breakthrough treatment that has become a new paradigm in treatment of recurrent or refractory B-cell lymphomas and pediatric or adult acute lymphoid leukemia. CAR T cells are a type of cellular immunotherapy that artificially enhances T cells to boost eradication of malignancy through activation of the native immune system. The CAR construct is a synthetically created functional cell receptor grafted onto previously harvested patient T cells, which bind to preselected tumor-associated antigens and thereby activate host immune signaling cascades to attack tumor cells. Advantages include a single treatment episode of 2-3 weeks and durable disease elimination, with remission rates of over 80%. Responses to therapy are more rapid than with conventional chemotherapy or immunotherapy, with intervening short-interval edema. CAR T-cell administration is associated with therapy-related toxic effects in a large percentage of patients, notably cytokine release syndrome, immune effect cell-associated neurotoxicity syndrome, and infections related to immunosuppression. Knowledge of the expected evolution of therapy response and potential adverse events in CAR T-cell therapy and correlation with the timeline of treatment are important to optimize patient care. Some toxic effects are radiologically evident, and familiarity with their imaging spectrum is key to avoiding misinterpretation. Other clinical toxic effects may be occult at imaging and are diagnosed on the basis of clinical assessment. Future directions for CAR T-cell therapy include new indications and expanded tumor targets, along with novel ways to capture T-cell activation with imaging. An invited commentary by Ramaiya and Smith is available online. Online supplemental material is available for this article. ^©RSNA, 2022.

CAR-T cell therapy in India requires a paradigm shift in training, education and health care processes

Chimeric antigen receptor (CAR)-T cell therapy has revolutionized the treatment of some kinds of cancers. Hundreds of companies and academic institutions are collaborating to develop gene-modified cell therapies using novel targets, different cell types, and manufacturing processes of autologous and allogenic cell therapies. The individualized, custom-made autologous CAR-T cell production platform remains a significant limiting factor for its large-scale clinical application. In this respect, the advances in standardization and automation of the process can have considerable impact on cost reduction. Development of off-the-shelf, ready-to-use universal killer cells can enable scaling up. Despite the wide use of this cell therapy in the United States, Europe and China, its development is limited in developing countries in Southeast Asia, Africa and Latin America. In this review, we focus on good manufacturing practices-compliant manufacturing requirements, operational logistics, and regulatory processes that need to be considered for high-quality gene-modified cell therapies from an Indian perspective. We also list the potential strategies to overcome challenges associated with translation to affordability and scalability.

CAR T Cells: Cancer Cell Surface Receptors Are the Target for Cancer Therapy

Immunotherapy has become a prominent strategy for the treatment of cancer. A method that improves the immune system's ability to attack a tumor (Enhances antigen binding). Targeted killing of malignant cells by adoptive transfer of chimeric antigen receptor (CAR) T cells is a promising immunotherapy technique in the treatment of cancers. For this purpose, the patient's immune cells, with genetic engineering aid, are loaded with chimeric receptors that have particular antigen binding and activate cytotoxic T lymphocytes. That increases the effectiveness of immune cells and destroying cancer cells. This review discusses the basic structure and function of CAR-T cells and how antigenic targets are identified to treat different cancers and address the disadvantages of this treatment for cancer.

Innate and Innate-Like Cells: The Future of Chimeric Antigen Receptor (CAR) Cell Therapy

Conventional αβ CAR-T cell-based approaches have revolutionized the field of cancer immunotherapy, but hurdles remain, especially for solid tumors. Novel strategies in conjunction with alternative cell types are therefore required for effective CAR-based therapies. In this respect, innate and innate-like cells with unique immune properties, such as natural killer (NK) cells, NKT cells, γδ T cells, and macrophages, are promising alternatives to αβ CAR-T adoptive therapy. We review the applicability of these cells in the context of CAR therapy, focusing on therapies under development, the advantages of these approaches relative to conventional CAR-T cells, and their potential in allogeneic therapies. We also discuss the inherent limitations of these cell types and approaches, and outline numerous strategies to overcome the associated obstacles.

T Cell Activation Machinery: Form and Function in Natural and Engineered Immune Receptors

The impressive success of chimeric antigen receptor (CAR)-T cell therapies in treating advanced B-cell malignancies has spurred a frenzy of activity aimed at developing CAR-T therapies for other cancers, particularly solid tumors, and optimizing engineered T cells for maximum clinical benefit in many different disease contexts. A rapidly growing body of design work is examining every modular component of traditional single-chain CARs as well as expanding out into many new and innovative engineered immunoreceptor designs that depart from this template. New approaches to immune cell and receptor engineering are being reported with rapidly increasing frequency, and many recent high-quality reviews (including one in this special issue) provide comprehensive coverage of the history and current state of the art in CAR-T and related cellular immunotherapies. In this review, we step back to examine our current understanding of the structure-function relationships in natural and engineered lymphocyte-activating receptors, with an eye towards evaluating how well the current-generation CAR designs recapitulate the most desirable features of their natural counterparts. We identify key areas that we believe are under-studied and therefore represent opportunities to further improve our grasp of form and function in natural and engineered receptors and to rationally design better therapeutics.

The Landscape of CAR-T Cell Clinical Trials against Solid Tumors-A Comprehensive Overview

Simple Summary

Certain immune cells, namely T cells, of cancer patients can be genetically manipulated to express so-called chimeric antigen receptors (CARs), which enables these cells to kill the tumor cells after recognition by the receptor. This therapy is very successful in the treatment of hematologic tumors such as lymphoma or leukemia. However, tumors growing as a solid mass are less susceptible to this kind of treatment. This review summarizes known data of all clinical trials using this therapy against solid tumors that are registered at clinicaltrials.gov.

Abstract

CAR-T cells showed great potential in the treatment of patients with hematologic tumors. However, the clinical efficacy of CAR-T cells against solid tumors lags behind. To obtain a comprehensive overview of the landscape of CAR-T cell clinical trials against this type of cancer, this review summarizes all the 196 studies registered at clinicaltrials.gov. Special focus is on: (1) geographical distribution; (2) targeted organs, tumor entities, and antigens; (3) CAR transfer methods, CAR formats, and extra features introduced into the T cells; and (4) patient pretreatments, injection sites, and safety measurements. Finally, the few data on clinical outcome are reported. The last assessment of clinicaltrials.gov for the data summarized in this paper was on 4 August 2020.

Nucleic Acid-Based Approaches for Tumor Therapy

Within the last decade, the introduction of checkpoint inhibitors proposed to boost the patients' anti-tumor immune response has proven the efficacy of immunotherapeutic approaches for tumor therapy. Furthermore, especially in the context of the development of biocompatible, cell type targeting nano-carriers, nucleic acid-based drugs aimed to initiate and to enhance anti-tumor responses have come of age. This review intends to provide a comprehensive overview of the current state of the therapeutic use of nucleic acids for cancer treatment on various levels, comprising (i) mRNA and DNA-based vaccines to be expressed by antigen presenting cells evoking sustained anti-tumor T cell responses, (ii) molecular adjuvants, (iii) strategies to inhibit/reprogram tumor-induced regulatory immune cells e.g., by RNA interference (RNAi), (iv) genetically tailored T cells and natural killer cells to directly recognize tumor antigens, and (v) killing of tumor cells, and reprograming of constituents of the tumor microenvironment by gene transfer and RNAi. Aside from further improvements of individual nucleic acid-based drugs, the major perspective for successful cancer therapy will be combination treatments employing conventional regimens as well as immunotherapeutics like checkpoint inhibitors and nucleic acid-based drugs, each acting on several levels to adequately counter-act tumor immune evasion.