CAR NK cell therapy in hematologic malignancies and solid tumors; obstacles and strategies to overcome the challenges

Natural killer cells: a new promising source for developing chimeric antigen receptor anti-cancer cells in hematological malignancies

In recent times, the application of CAR-T cell treatment has significantly progressed, showing auspicious treatment outcomes in hematologic malignancies. However, along with these advances, certain limitations and challenges hurdle the widespread utilization of this technology. Recently, CAR-NK cells have gained attention in cancer treatment, as this approach has an important advantage over CART therapy (i.e. no need for HLA matching) for targeting foreign cells. This review aims to explore the benefits of CAR NK cell therapy, and generation strategies, as well as the challenges and limitations hindering the application of CAR NK cells in experimental studies and trials on hematologic malignancies.

Tumor Biology Hides Novel Therapeutic Approaches to Diffuse Large B-Cell Lymphoma: A Narrative Review

Diffuse large B-cell lymphoma (DLBCL) is a malignancy of immense biological and clinical heterogeneity. Based on the transcriptomic or genomic approach, several different classification schemes have evolved over the years to subdivide DLBCL into clinically (prognostically) relevant subsets, but each leaves unclassified samples. Herein, we outline the DLBCL tumor biology behind the actual and potential drug targets and address the challenges and drawbacks coupled with their (potential) use. Therapeutic modalities are discussed, including small-molecule inhibitors, naked antibodies, antibody-drug conjugates, chimeric antigen receptors, bispecific antibodies and T-cell engagers, and immune checkpoint inhibitors. Candidate drugs explored in ongoing clinical trials are coupled with diverse toxicity issues and refractoriness to drugs. According to the literature on DLBCL, the promise for new therapeutic targets lies in epigenetic alterations, B-cell receptor and NF-κB pathways. Herein, we present putative targets hiding in lipid pathways, ferroptosis, and the gut microbiome that could be used in addition to immuno-chemotherapy to improve the general health status of DLBCL patients, thus increasing the chance of being cured. It may be time to devote more effort to exploring DLBCL metabolism to discover novel druggable targets. We also performed a bibliometric and knowledge-map analysis of the literature on DLBCL published from 2014-2023.

Radiotherapy enhances the anti-tumor effect of CAR-NK cells for hepatocellular carcinoma

BACKGROUND

Chimeric antigen receptor (CAR)-NK cell therapy has shown remarkable clinical efficacy and safety in the treatment of hematological malignancies. However, this efficacy was limited in solid tumors owing to hostile tumor microenvironment (TME). Radiotherapy is commonly used for solid tumors and proved to improve the TME. Therefore, the combination with radiotherapy would be a potential strategy to improve therapeutic efficacy of CAR-NK cells for solid tumors.

METHODS

Glypican-3 (GPC3) was used as a target antigen of CAR-NK cell for hepatocellular carcinoma (HCC). To promote migration towards HCC, CXCR2-armed CAR-NK92 cells targeting GPC3 were first developed, and their cytotoxic and migration activities towards HCC cells were evaluated. Next, the effects of irradiation on the anti-tumor activity of CAR-NK92 cells were assessed in vitro and in HCC-bearing NCG mice. Lastly, to demonstrate the potential mechanism mediating the sensitized effect of irradiation on CAR-NK cells, the differential gene expression profiles induced by irradiation were analyzed and the expression of some important ligands for the NK-cell activating receptors were further determined by qRT-PCR and flow cytometry.

RESULTS

In this study, we developed CXCR2-armed GPC3-targeting CAR-NK92 cells that exhibited specific and potent killing activity against HCC cells and the enhanced migration towards HCC cells. Pretreating HCC cells with irradiation enhanced in vitro anti-HCC effect and migration activity of CXCR2-armed CAR-NK92 cells. We further found that only high-dose (8 Gy) but not low-dose (2 Gy) irradiation in one fraction could significantly enhanced in vivo anti-HCC activity of CXCR2-armed CAR-NK92 cells. Irradiation with 8 Gy significantly up-regulated the expression of NK cell-activating ligands on HCC cells.

CONCLUSIONS

Our results indicate the evidence that irradiation could efficiently enhance the anti-tumor effect of CAR-NK cells in solid tumor model. The combination with radiotherapy would be an attractive strategy to improve therapeutic efficacy of CAR-NK cells for solid tumors.

Non-viral approaches in CAR-NK cell engineering: connecting natural killer cell biology and gene delivery

Natural Killer (NK) cells are exciting candidates for cancer immunotherapy with potent innate cytotoxicity and distinct advantages over T cells for Chimeric Antigen Receptor (CAR) therapy. Concerns regarding the safety, cost, and scalability of viral vectors has ignited research into non-viral alternatives for gene delivery. This review comprehensively analyses recent advancements and challenges with non-viral genetic modification of NK cells for allogeneic CAR-NK therapies. Non-viral alternatives including electroporation and multifunctional nanoparticles are interrogated with respect to CAR expression and translational responses. Crucially, the link between NK cell biology and design of drug delivery technologies are made, which is essential for development of future non-viral approaches. This review provides valuable insights into the current state of non-viral CAR-NK cell engineering, aimed at realising the full potential of NK cell-based immunotherapies.

Off-the-shelf CAR-NK cells targeting immunogenic cell death marker ERp57 execute robust antitumor activity and have a synergistic effect with ICD inducer oxaliplatin

BACKGROUND

Chimeric antigen receptor natural killer (CAR-NK) therapy holds great promise for treating hematologic tumors, but its efficacy in solid tumors is limited owing to the lack of suitable targets and poor infiltration of engineered NK cells. Here, we explore whether immunogenic cell death (ICD) marker ERp57 translocated from endoplasmic reticulum to cell surface after drug treatment could be used as a target for CAR-NK therapy.

METHODS

To target ERp57, a VHH phage display library was used for screening ERp57-targeted nanobodies (Nbs). A candidate Nb with high binding affinity to both human and mouse ERp57 was used for constructing CAR-NK cells. Various in vitro and in vivo studies were performed to assess the antitumor efficacy of the constructed CAR-NK cells.

RESULTS

We demonstrate that the translocation of ERp57 can not only be induced by low-dose oxaliplatin (OXP) treatment but also is spontaneously expressed on the surface of various types of tumor cell lines. Our results show that G6-CAR-NK92 cells can effectively kill various tumor cell lines in vitro on which ERp57 is induced or intrinsically expressed, and also exhibit potent antitumor effects in cancer cell-derived xenograft and patient-derived xenograft mouse models. Additionally, the antitumor activity of G6-CAR-NK92 cells is synergistically enhanced by the low-dose ICD-inducible drug OXP.

CONCLUSION

Collectively, our findings suggest that ERp57 can be leveraged as a new tumor antigen for CAR-NK targeting, and the resultant CAR-NK cells have the potential to be applied as a broad-spectrum immune cell therapy for various cancers by combining with ICD inducer drugs.

Advanced Strategies of CAR-T Cell Therapy in Solid Tumors and Hematological Malignancies

Chimeric antigen receptor T-cells, known as CAR-T cells, represent a promising breakthrough in the realm of adoptive cell therapy. These T-cells are genetically engineered to carry chimeric antigen receptors that specifically target tumors. They have achieved notable success in the treatment of blood-related cancers, breathing new life into this field of medical research. However, numerous obstacles limit chimeric antigen receptors T-cell therapy's efficacy, such as it cannot survive in the body long. It is prone to fatigue and exhaustion, leading to difficult tumor elimination and repeated recurrence, affecting solid tumors and hematological malignancies. The challenges posed by solid tumors, especially in the context of the complex solid-tumor microenvironment, require specific strategies. This review outlines recent advancements in improving chimeric antigen receptors T-cell therapy by focusing on the chimeric antigen receptors protein, modifying T-cells, and optimizing the interaction between T-cells and other components within the tumor microenvironment. This article aims to provide an extensive summary of the latest discoveries regarding CAR-T cell therapy, encompassing its application across various types of human cancers. Moreover, it will delve into the obstacles that have emerged in recent times, offering insights into the challenges faced by this innovative approach. Finally, it highlights novel therapeutic options in treating hematological and solid malignancies with chimeric antigen receptors T-cell therapies.

Chimeric antigen receptor engineered natural killer cells for cancer therapy

Natural killer (NK) cells, a unique component of the innate immune system, are inherent killers of stressed and transformed cells. Based on their potent capacity to kill cancer cells and good tolerance of healthy cells, NK cells have been successfully employed in adoptive cell therapy to treat cancer patients. In recent years, the clinical success of chimeric antigen receptor (CAR)-T cells has proven the vast potential of gene-manipulated immune cells as the main force to fight cancer. Following the lessons learned from mature gene-transfer technologies and advanced strategies in CAR-T therapy, NK cells have been rapidly explored as a promising candidate for CAR-based therapy. An exponentially growing number of studies have employed multiple sources of CAR-NK cells to target a wide range of cancer-related antigens, showing remarkable outcomes and encouraging safety profiles. Clinical trials of CAR-NK cells have also shown their impressive therapeutic efficacy in the treatment of hematological tumors, but CAR-NK cell therapy for solid tumors is still in the initial stages. In this review, we present the favorable profile of NK cells as a potential platform for CAR-based engineering and then summarize the outcomes and strategies of CAR-NK therapies in up-to-date preclinical and clinical investigations. Finally, we evaluate the challenges remaining in CAR-NK therapy and describe existing strategies that can assist us in devising future prospective solutions.

Targeted therapy and immunotherapy for T cell acute lymphoblastic leukemia/lymphoma

T cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL) is an aggressive malignancy of progenitor T cells. Despite significant improvements in survival of T-ALL/LBL over the past decades, treatment of relapsed and refractory T-ALL (R/R T-ALL/LBL) remains extremely challenging. The prognosis of R/R T-ALL/LBL patients who are intolerant to intensive chemotherapy remains poor. Therefore, innovative approaches are needed to further improve the survival of R/R T-ALL/LBL patients. With the widespread use of next-generation sequencing in T-ALL/LBL, a range of new therapeutic targets such as NOTCH1 inhibitors, JAK-STAT inhibitors, and tyrosine kinase inhibitors have been identified. These findings led to pre-clinical studies and clinical trials of molecular targeted therapy in T-ALL/LBL. Furthermore, immunotherapies such as CD7 CAR T cell therapy and CD5 CAR T cell therapy have shown profound response rate in R/R T-ALL/LBL. Here, we review the progress of targeted therapies and immunotherapies for T-ALL/LBL, and look at the future directions and challenges for the further use of these therapies in T-ALL/LBL.

Synthetic engineered bacteria for cancer therapy

INTRODUCTION

Cancer mortality worldwide highlights the urgency for advanced therapeutic methods to fill the gaps in conventional cancer therapies. Bacteriotherapy is showing great potential in tumor regression due to the motility and colonization tendencies of bacteria. However, the complicated in vivo environment and tumor pathogenesis hamper the therapeutic outcomes. Synthetic engineering methods endow bacteria with flexible abilities both at the extracellular and intracellular levels to meet treatment requirements. In this review, we introduce synthetic engineering methods for bacterial modifications. We highlight the recent progress in engineered bacteria and explore how these synthetic methods endow bacteria with superior abilities in cancer therapy. The current clinical translations are further discussed. Overall, this review may shed light on the advancement of engineered bacteria for cancer therapy.

AREAS COVERED

Recent progress in synthetic methods for bacterial engineering and specific examples of their applications in cancer therapy are discussed in this review.

EXPERT OPINION

Bacteriotherapy bridges the gaps of conventional cancer therapies through the natural motility and colonization tendency of bacteria, as well as their synthetic engineering. Nevertheless, to fulfill the bacteriotherapy potential and move into clinical trials, more research focusing on its safety concerns should be conducted.

Research progress in leveraging biomaterials for enhancing NK cell immunotherapy

NK cell immunotherapy is a promising antitumor therapeutic modality after the development of T cell immunotherapy. Structural modification of NK cells with biomaterials may provide a precise, efficient, and low-cost strategy to enhance NK cell immunotherapy. The biomaterial modification of NK cells can be divided into two strategies: surface engineering with biomaterials and intracellular modification. The surface engineering strategies include hydrophobic interaction of lipids, receptor-ligand interaction between membrane proteins, covalent binding to amino acid residues, click reaction and electrostatic interaction. The intracellular modification strategies are based on manipulation by nanotechnology using membranous materials from various sources of NK cells (such as exosome, vesicle and cytomembranes). Finally, the biomaterials-based strategies regulate the recruitment, recognition and cytotoxicity of NK cells in the solid tumor site in situ to boost the activity of NK cells in the tumor. This article reviews the recent research progress in enhancing NK cell therapy based on biomaterial modification, to provide a reference for further researches on engineering NK cell therapy with biomaterials.

Efficient Redirection of NK Cells by Genetic Modification with Chemokine Receptors CCR4 and CCR2B

Natural killer (NK) cells are a subset of lymphocytes that offer great potential for cancer immunotherapy due to their natural anti-tumor activity and the possibility to safely transplant cells from healthy donors to patients in a clinical setting. However, the efficacy of cell-based immunotherapies using both T and NK cells is often limited by a poor infiltration of immune cells into solid tumors. Importantly, regulatory immune cell subsets are frequently recruited to tumor sites. In this study, we overexpressed two chemokine receptors, CCR4 and CCR2B, that are naturally found on T regulatory cells and tumor-resident monocytes, respectively, on NK cells. Using the NK cell line NK-92 as well as primary NK cells from peripheral blood, we show that genetically engineered NK cells can be efficiently redirected using chemokine receptors from different immune cell lineages and migrate towards chemokines such as CCL22 or CCL2, without impairing the natural effector functions. This approach has the potential to enhance the therapeutic effect of immunotherapies in solid tumors by directing genetically engineered donor NK cells to tumor sites. As a future therapeutic option, the natural anti-tumor activity of NK cells at the tumor sites can be increased by co-expression of chemokine receptors with chimeric antigen receptors (CAR) or T cell receptors (TCR) on NK cells can be performed in the future.

CAR-NK cells: a promising cellular immunotherapy in lymphoma

INTRODUCTION

New methods in cancer immunotherapy, such as chimeric antigen receptor (CAR)-T cells, have shown promising results in destroying malignant cells. However, limitations and side effects of CAR-T cell therapy, such as graft-versus-host disease (GVHD), neurotoxicity, and cytokine release syndrome, have motivated researchers to investigate safer alternative cells like natural killer (NK) cells.

AREA COVERED

NK cells can effectively recognize hematologic malignant cells and destroy them. Many clinical and preclinical studies investigate the efficacy of CAR-NK cells in treating lymphoma and other hematologic malignancies. The results of published clinical trials and preclinical studies have shown that CAR-NK cells could be an appropriate choice for treating lymphoma. In this review, we discuss the characteristics of CAR-NK cells, their role in treating B-cell and T-cell lymphoma, and the challenges faced by using them. We also highlight clinical trials using CAR-NK cells for treating lymphoma.

EXPERT OPINION

CAR-NK cells have shown promising results in cancer therapy, especially B-cell lymphoma, with a much lower risk for GVHD, cytokine release syndrome, and neurotoxicity than CAR-T cells. Further investigations are required to overcome the obstacles of CAR-NK cell therapy, both generally, and in cancers like T-cell lymphoma.

Strategies to enhance CAR-T persistence

Chimeric antigen receptor T (CAR-T) cell therapy has significantly improved the life expectancy for patients with refractory or relapse B cell lymphoma. As for B cell acute lymphoblastic leukemia (B-ALL), although the primary response rate is promising, the high incidence of early relapse has caused modest long-term survival with CAR-T cell alone. One of the main challenges is the limited persistence of CAR-T cells. To further optimize the clinical effects of CAR-T cells, many studies have focused on modifying the CAR structure and regulating CAR-T cell differentiation. In this review, we focus on CAR-T cell persistence and summarize the latest progress and strategies adopted during the in vitro culture stage to optimize CAR-T immunotherapy by improving long-term persistence. Such strategies include choosing a suitable cell source, improving culture conditions, combining CAR-T cells with conventional drugs, and applying genetic manipulations, all of which may improve the survival of patients with hematologic malignancies by reducing the probability of recurrence after CAR-T cell infusion and provide clues for solid tumor CAR-T cell therapy development.

A bibliometric and scientific knowledge-map study of the chimeric antigen receptor (CAR) natural killer (NK) cell-related research from 2010 to 2022

Objectives

As emerging adoptive immunotherapy after CAR-T cell therapy, CAR-NK cell therapy has been developing rapidly in recent years. Presently, the research on CAR-NK cells has become a hotspot in the field of tumor immunotherapy.

Methods

In this descriptive study, CtieSpace and VOSviewer were used to perform the bibliometric and scientific knowledge-map analysis of articles and reviews related to CAR-NK cells.

Results

5371 authors from 715 institutions in 65 countries published 1028 papers about CAR-NK cells in 346 journals. The number of publications related to CAR-NK cells was increasing overall, especially from 2018 to 2021. The United States was in a leading position. The most active institution was Univ Texas, MD Anderson Cancer Center (USA). The journal with the most publications was Frontiers in immunology, and the most co-cited journal was Blood. The researcher with the most published papers was Winfried S. Wels, while the most co-cited researcher was Shannon L Maude. The research of CAR-NK cells in hematological malignancies and solid tumors (especially the selection of targets and the evaluation of efficacy and safety) was a research hotspot in this field. The emerging topics mainly included three aspects. First, further improve the proliferation and persistence of NK cells in vivo. Secondly, optimizing and improving the CAR structure for NK cells to improve the anti-tumor ability of CAR-NK cells. Thirdly, the related research of CRISPR/Cas9 gene-editing technology in constructing engineered immune cells.

Conclusion

In this study, a bibliometric and scientific knowledge-map study provided a unique and objective perspective for the CAR-NK cell field. This information would provide a helpful reference for researchers interested in this field.