Natural killer cell-based immunotherapy: From transplantation toward targeting cancer stem cells

Role of intracranial bone marrow mesenchymal stem cells in stroke recovery: A focus on post-stroke inflammation and mitochondrial transfer

Stem cell therapy has become a hot research topic in the medical field in recent years, with enormous potential for treating a variety of diseases. In particular, bone marrow mesenchymal stem cells (BMSCs) have wide-ranging applications in the treatment of ischemic stroke, autoimmune diseases, tissue repair, and difficult-to-treat diseases. BMSCs can differentiate into multiple cell types and exhibit strong immunomodulatory properties. Although BMSCs can regulate the inflammatory response activated after stroke, the mechanism by which BMSCs regulate inflammation remains unclear and requires further study. Recently, stem cell therapy has emerged as a potentially effective approach for enhancing the recovery process following an ischemic stroke. For example, by regulating post-stroke inflammation and by transferring mitochondria to exert therapeutic effects. Therefore, this article reviews the therapeutic effects of intracranial BMSCs in regulating post-stroke inflammation and mitochondrial transfer in the treatment of stroke, providing a basis for further research.

Cancer stem cells: advances in knowledge and implications for cancer therapy

Cancer stem cells (CSCs), a small subset of cells in tumors that are characterized by self-renewal and continuous proliferation, lead to tumorigenesis, metastasis, and maintain tumor heterogeneity. Cancer continues to be a significant global disease burden. In the past, surgery, radiotherapy, and chemotherapy were the main cancer treatments. The technology of cancer treatments continues to develop and advance, and the emergence of targeted therapy, and immunotherapy provides more options for patients to a certain extent. However, the limitations of efficacy and treatment resistance are still inevitable. Our review begins with a brief introduction of the historical discoveries, original hypotheses, and pathways that regulate CSCs, such as WNT/β-Catenin, hedgehog, Notch, NF-κB, JAK/STAT, TGF-β, PI3K/AKT, PPAR pathway, and their crosstalk. We focus on the role of CSCs in various therapeutic outcomes and resistance, including how the treatments affect the content of CSCs and the alteration of related molecules, CSCs-mediated therapeutic resistance, and the clinical value of targeting CSCs in patients with refractory, progressed or advanced tumors. In summary, CSCs affect therapeutic efficacy, and the treatment method of targeting CSCs is still difficult to determine. Clarifying regulatory mechanisms and targeting biomarkers of CSCs is currently the mainstream idea.

Cancer stem cell-immune cell crosstalk in the tumor microenvironment for liver cancer progression

Crosstalk between cancer cells and the immune microenvironment is determinant for liver cancer progression. A tumor subpopulation called liver cancer stem cells (CSCs) significantly accounts for the initiation, metastasis, therapeutic resistance, and recurrence of liver cancer. Emerging evidence demonstrates that the interaction between liver CSCs and immune cells plays a crucial role in shaping an immunosuppressive microenvironment and determining immunotherapy responses. This review sheds light on the bidirectional crosstalk between liver CSCs and immune cells for liver cancer progression, as well as the underlying molecular mechanisms after presenting an overview of liver CSCs characteristic and their microenvironment. Finally, we discuss the potential application of liver CSCs-targeted immunotherapy for liver cancer treatment.

Circulating tumor cells participate in the formation of microvascular invasion and impact on clinical outcomes in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common malignant tumor worldwide. Although the treatment strategies have been improved in recent years, the long-term prognosis of HCC is far from satisfactory mainly due to high postoperative recurrence and metastasis rate. Vascular tumor thrombus, including microvascular invasion (MVI) and portal vein tumor thrombus (PVTT), affects the outcome of hepatectomy and liver transplantation. If vascular invasion could be found preoperatively, especially the risk of MVI, more reasonable surgical selection will be chosen to reduce the risk of postoperative recurrence and metastasis. However, there is a lack of reliable prediction methods, and the formation mechanism of MVI/PVTT is still unclear. At present, there is no study to explore the possibility of tumor thrombus formation from a single circulating tumor cell (CTC) of HCC, nor any related study to describe the possible leading role and molecular mechanism of HCC CTCs as an important component of MVI/PVTT. In this study, we review the current understanding of MVI and possible mechanisms, discuss the function of CTCs in the formation of MVI and interaction with immune cells in the circulation. In conclusion, we discuss implications for potential therapeutic targets and the prospect of clinical treatment of HCC.

Impact of a new liver immune status index among patients with hepatocellular carcinoma after initial hepatectomy

Aim

The anti-tumor effects of natural killer (NK) cells vary among individuals. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) expressed on liver NK cells is a marker of anti-tumor cytotoxicity against hepatocellular carcinoma (HCC) in immune cell therapy. This study aimed to develop a liver immune status index (LISI) that predicts low TRAIL expression and validates its ability to predict recurrence after initial hepatectomy for primary HCC.

Methods

A functional analysis of liver NK cells co-cultured with interleukin-2 for 3 days was performed of 40 liver transplant donors. The LISI, which predicted low TRAIL expression (25% quartile: <33%) in liver NK cells, was calculated using multiple logistic regression analysis. Next, 586 initial hepatectomy cases were analyzed based on the LISI.

Results

Our model was based on the Fibrosis-4 index+0.1 (odds ratio [OR], 1.33), body mass index (OR, 0.61), and albumin levels+0.1 (OR, 0.54). The area under the receiver operating characteristic curve (AUC) of the LISI for low TRAIL expression was 0.89. Stratification of the recurrence rates (RR) revealed that LISI was an independent predictive factor of RR (moderate risk: hazard ratio, 1.44; high risk: hazard ratio, 3.02). The AUC was similar for the LISI, albumin-indocyanine green evaluation grade, albumin-bilirubin score, and geriatric nutritional risk index for predicting RR. Among the vascular invasion cases, the LISI was more useful than the other indexes.

Conclusion

Our model facilitates the prediction of RR in high-risk patients by providing LISI to predict the anti-tumor effects of NK cells.

Natural killer cell therapy targeting cancer stem cells: Old wine in a new bottle

A small proportion of cancer cells that have stem cell-like properties are known as cancer stem cells (CSCs). They can be used to identify malignant tumor phenotypes and patients with poor prognosis. Targeting these cells has been shown to improve the effectiveness of cancer therapies. Owing to the nature of CSCs, they are resistant to conventional treatment methods such as radio- and chemotherapy. Therefore, more effective anti-CSC therapies are required. Immunotherapy, including natural killer (NK) and T cell therapy, has demonstrated the ability to eliminate CSCs. NK cells have demonstrated superior anti-CSC capabilities compared to T cells in recognizing low levels of major histocompatibility complex (MHC) class I expression. However, CSC escape also occurs during NK cell therapy. It is important to determine CSC-specific immune evasion mechanisms and find out potential solutions to optimize NK cell function. Therefore, this review discusses promising strategies that can improve the efficiency of NK cell therapy in treating CSCs, and aims to provide a reference for future research.

Natural killer cell-derived exosomes for cancer immunotherapy: innovative therapeutics art

Chimeric antigen receptor natural killer cells (CAR-NK) promote off-the-shelf cellular therapy for solid tumors and malignancy.However,, the development of CAR-NK is due to their immune surveillance uncertainty and cytotoxicity challenge was restricted. Natural killer cell-derived exosome (NK-Exo) combine crucial targeted cellular therapies of NK cell therapies with unique non-toxic Exo as a self-origin shuttle against cancer immunotherapy. This review study covers cytokines, adoptive (autologous and allogenic) NK immunotherapy, stimulatory and regulatory functions, and cell-free derivatives from NK cells. The future path of NK-Exo cytotoxicity and anti-tumor activity with considering non-caspase-independent/dependent apoptosis and Fas/FasL pathway in cancer immunotherapy. Finally, the significance and implication of NK-Exo therapeutics through combination therapy and the development of emerging approaches for the purification and delivery NK-Exo to severe immune and tumor cells and tissues were discussed in detail.

Analysis of NK-92 cytotoxicity in nasopharyngeal carcinoma cell lines and patient-derived xenografts using impedance-based growth method

Natural killer (NK) cells are innate immune cells that can remove viral-infected tumour cells without antigen priming. This characteristic offers NK cells an edge over other immune cells as a potential therapy for nasopharyngeal carcinoma (NPC). In this study, we report how cytotoxicity was evaluated in target NPC cell lines and patient-derived xenograft (PDX) cells with effector NK-92, a commercially available NK cell line, by using xCELLigence RTCA system (a real-time, label-free impedance-based monitoring platform). Cell viability, proliferation and cytotoxicity were examined by RTCA. Cell morphology, growth and cytotoxicity were also monitored by microscopy. RTCA and microscopy showed that both target and effector cells were able to proliferate normally and to maintain original morphology in co-culture medium as they were in their own respective culture medium. As target and effector (T:E) cell ratios increased, cell viability as measured by arbitrary cell index (CI) values in RTCA decreased in all cell lines and PDX cells. NPC PDX cells were more sensitive to the cytotoxicity effect of NK-92 cells, than the NPC cell lines. These data were substantiated by GFP-based microscopy. We have shown how the RTCA system can be used for a high throughput screening of the effects of NK cells in cancer studies to obtain data such as cell viability, proliferation and cytotoxicity.

Engaging stemness improves cancer immunotherapy

Intra-tumoral immune cells promote the stemness of cancer stem cells (CSCs) in the tumor microenvironment (TME). CSCs promote tumor progression, relapse, and resistance to immunotherapy. Cancer stemness induces the expression of neoantigens and neo-properties in CSCs, creating an opportunity for targeted immunotherapies. Isolation of stem-like T cells or retaining stemness in T clonotypes strategies produces exhaustion-resistance T cells with superior re-expansion capacity and long-lasting responses after adoptive cell therapies. Stem cells-derived NK cells may be the next generation of NK cell products for immunotherapy. Here, we have reviewed mechanisms by which stemness factors modulated the immunoediting of the TME and summarized the potentials of CSCs in the development of immunotherapy regimens, including CAR-T cells, CAR-NK cells, cancer vaccines, and monoclonal antibodies. We have discussed the natural or genetically engineered stem-like T cells and stem cell-derived NK cells with increased cytotoxicity to tumor cells. Finally, we have provided a perspective on approaches that may improve the therapeutic efficacy of these novel adoptive cell-based products in targeting immunosuppressive TME.

Current state of NK cell-mediated immunotherapy in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) has become one of the most common hematological diseases in western countries, with an annual incidence of 42/100,000. Conventional chemotherapy and targeted therapeutic drugs showed limitations in prognosis or in efficiency in high-risk patients. Immunotherapy represented is one of the most effective therapeutic approaches with the potential of better effect and prognosis. Natural killer (NK) cells are good options for immunotherapy as they can effectively mediate anti-tumor activity of immune system by expressing activating and inhibiting receptors and recognizing specific ligands on various tumor cells. NK cells are critical in the immunotherapy of CLL by enhancing self-mediated antibody-dependent cytotoxicity (ADCC), allogeneic NK cell therapy and chimeric antigen receptor-natural killer (CAR-NK) cell therapy. In this article, we reviewed the features, working mechanisms, and receptors of NK cells, and the available evidence of the advantages and disadvantages of NK cell-based immunotherapies, and put forward future study directions in this field.

Enhanced anticancer efficacy of primed natural killer cells via coacervate-mediated exogenous interleukin-15 delivery

Effective exogenous delivery of interleukin (IL)-15 to natural killer (NK) cells with subsequent anticancer efficacy could be a promising immune cell-based cancer immunotherapy. For the protection of encapsulated cargo IL-15 while maintaining its bioactivity under physiological conditions, we utilized a coacervate (Coa) consisting of a cationic methoxy polyethylene glycol-poly(ethylene arginyl aspartate diglyceride) (mPEG-PEAD) polymer, anionic counterpart heparin, and cargo IL-15. mPEGylation into the backbone cation effectively preserved the colloidal stability of Coa in harsh environments and enhanced the protection of cargo IL-15 than normal Coa without mPEGylation. Proliferation and anticancer efficacy of primed NK cells through co-culture with multiple cancer cell lines were enhanced in the mPEG-Coa group due to the maintained bioactivity of cargo IL-15 during the ex vivo expansion of NK cells. These facilitated functions of NK cells were also supported by the increased expression of mRNAs related to anticancer effects of NK cells, including cytotoxic granules, death ligands, anti-apoptotic proteins, and activation receptors. In summary, our Coa-mediated exogenous IL-15 delivery could be an effective ex vivo priming technique for NK cells with sustained immune activation that can effectively facilitate its usage for cancer immunotherapy.

Recent advances to enhance the immunomodulatory potential of mesenchymal stem cells

Considering the unique therapeutic potential of mesenchymal stem cells (MSCs), including their immunosuppressive and immunomodulatory properties as well as their ability to improve tissue regeneration, these cells have attracted the attention of scientists and clinicians for the treatment of different inflammatory and immune system mediated disorders. However, various clinical trials using MSCs for the therapeutic purpose are conflicting and differ from the results of promising preclinical studies. This inconsistency is caused by several factors such as poor migration and homing capacities, low survival rate, low level of proliferation and differentiation, and donor-dependent variation of the cells. Enhancement and retention of persistent therapeutic effects of the cells remain a challenge to overcome in MSC-based therapy. In this review, we summarized various approaches to enhance the clinical outcomes of MSC-based therapy as well as revised current and future perspectives for the creation of cellular products with improved potential for diverse clinical applications.

iPSCs in NK Cell Manufacturing and NKEV Development

Natural killer (NK) cell immunotherapies for cancer can complement existing T cell therapies while benefiting from advancements already made in the immunotherapy field. For NK cell manufacturing, induced pluripotent stem cells (iPSCs) offer advantages including eliminating donor variation and providing an ideal platform for genome engineering. At the same time, extracellular vesicles (EVs) have become a major research interest, and purified NK cell extracellular vesicles (NKEVs) have been shown to reproduce the key functions of their parent NK cells. NKEVs have the potential to be developed into a standalone therapeutic with reduced complexity and immunogenicity compared to cell therapies. This review explores the role iPSC technology can play in both NK cell manufacturing and NKEV development.

Expression of proliferation-related genes in BM-MSC-treated ALL cells in hypoxia condition is regulated under the influence of epigenetic factors in-vitro

Mesenchymal stem cells affect ALL cell biology under hypoxic conditions. We studied survival, proliferation, expression, and promoter methylation levels of essential genes involved in expanding MOLT-4 cells co-cultured with BM-MSC under the hypoxic condition. Here, MOLT-4 cells were co-cultured with BMMSCs under hypoxic conditions. First, the apoptosis rate was evaluated by Flow cytometry. Then, MOLT-4 cells' proliferation rate was assessed using MTT assay, and the expressions and methylation rates of genes were determined by qRT-PCR and MS-qPCR, respectively. The results showed that although MOLT-4 cells proliferation and survival rates were reduced under hypoxic conditions, this reduction was not statistically significant. Also, we showed that hypoxic conditions caused upregulation of candidate genes and affected their methylation status. Besides, it was revealed that Pontin was downregulated, while KDM3A, SKP2, and AURKA had an upward trend in the presence of MOLT-4 cells plus BM-MSC. The co-culture of leukemia cells with BMMSCs under hypoxic conditions may be a potential therapeutic approach for ALL.

Immune evader cancer stem cells direct the perspective approaches to cancer immunotherapy

Exploration of tumor immunity leads to the development of immune checkpoint inhibitors and cell-based immunotherapies which improve the clinical outcomes in several tumor types. However, the poor clinical efficacy of these treatments observed for other tumors could be attributed to the inherent complex tumor microenvironment (TME), cellular heterogeneity, and stemness driven by cancer stem cells (CSCs). CSC-specific characteristics provide the bulk tumor surveillance and resistance to entire eradication upon conventional therapies. CSCs-immune cells crosstalk creates an immunosuppressive TME that reshapes the stemness in tumor cells, resulting in tumor formation and progression. Thus, identifying the immunological features of CSCs could introduce the therapeutic targets with powerful antitumor responses. In this review, we summarized the role of immune cells providing CSCs to evade tumor immunity, and then discussed the intrinsic mechanisms represented by CSCs to promote tumors' resistance to immunotherapies. Then, we outlined potent immunotherapeutic interventions followed by a perspective outlook on the use of nanomedicine-based drug delivery systems for controlled modulation of the immune system.

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.

Natural Killer Cell-Mediated Immunotherapy for Leukemia

Simple Summary

Conventional therapies such as chemotherapy and radiation in leukemia increase infection susceptibility, adverse side effects and immune cell inactivation. Natural killer (NK) cells are the first line of defense against cancer and are critical in the recognition and cytolysis of rapidly dividing and abnormal cell populations. In this review, we describe NK cells and NK cell receptors, functional impairment of NK cells in leukemia, NK cell immunotherapies currently under investigation including monoclonal antibodies (mAbs), adoptive transfer, chimeric antigen receptor-NKs (CAR-NKs), bi-specific/tri-specific killer engagers (BiKEs/TriKEs) and potential targets of NK cell-mediated immunotherapy for leukemia in the future.

Abstract

Leukemia is a malignancy of the bone marrow and blood resulting from the abnormal differentiation of hematopoietic stem cells (HSCs). There are four main types of leukemia including acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myeloid leukemia (CML), and chronic lymphocytic leukemia (CLL). While chemotherapy and radiation have been conventional forms of treatment for leukemia, these therapies increase infection susceptibility, adverse side effects and immune cell inactivation. Immunotherapies are becoming promising treatment options for leukemia, with natural killer (NK) cell-mediated therapy providing a specific direction of interest. The role of NK cells is critical for cancer cell elimination as these immune cells are the first line of defense against cancer proliferation and are involved in both recognition and cytolysis of rapidly dividing and abnormal cell populations. NK cells possess various activating and inhibitory receptors, which regulate NK cell function, signaling either inhibition and continued surveillance, or activation and subsequent cytotoxic activity. In this review, we describe NK cells and NK cell receptors, functional impairment of NK cells in leukemia, NK cell immunotherapies currently under investigation, including monoclonal antibodies (mAbs), adoptive transfer, chimeric antigen receptor-NKs (CAR-NKs), bi-specific/tri-specific killer engagers (BiKEs/TriKEs) and future potential targets of NK cell-based immunotherapy for leukemia.

iPSC-Derived Natural Killer Cells for Cancer Immunotherapy

The discovery of human pluripotent stem cells (PSCs) at the turn of the century opened the door to a new generation of regenerative medicine research. Among PSCs, the donors available for induced pluripotent stem cells (iPSCs) are greatest, providing a potentially universal cell source for all types of cell therapies including cancer immunotherapies using natural killer (NK cells). Unlike primary NK cells, those prepared from iPSCs can be prepared with a homogeneous quality and are easily modified to exert a desired response to tumor cells. There already exist several protocols to genetically modify and differentiate iPSCs into NK cells, and each has its own advantages with regards to immunotherapies. In this short review, we detail the benefits of using iPSCs in NK cell immunotherapies and discuss the challenges that must be overcome before this approach becomes mainstream in the clinic.

Cellular Immunotherapy Targeting Cancer Stem Cells: Preclinical Evidence and Clinical Perspective

The term “cancer stem cells” (CSCs) commonly refers to a subset of tumor cells endowed with stemness features, potentially involved in chemo-resistance and disease relapses. CSCs may present peculiar immunogenic features influencing their homeostasis within the tumor microenvironment. The susceptibility of CSCs to recognition and targeting by the immune system is a relevant issue and matter of investigation, especially considering the multiple emerging immunotherapy strategies. Adoptive cellular immunotherapies, especially those strategies encompassing the genetic redirection with chimeric antigen receptors (CAR), hold relevant promise in several tumor settings and might in theory provide opportunities for selective elimination of CSC subsets. Initial dedicated preclinical studies are supporting the potential targeting of CSCs by cellular immunotherapies, indirect evidence from clinical studies may be derived and new studies are ongoing. Here we review the main issues related to the putative immunogenicity of CSCs, focusing on and highlighting the existing evidence and opportunities for cellular immunotherapy approaches with T and non-T antitumor lymphocytes.

Identification of Immune-Related Therapeutically Relevant Biomarkers in Breast Cancer and Breast Cancer Stem Cells by Transcriptome-Wide Analysis: A Clinical Prospective Study

Cancer stem cells (CSCs) represent a subset of tumor cells that are responsible for recurrence and metastasis of tumors. These cells are resistant to radiotherapy and chemotherapy. Immunotherapeutic strategies that target CSCs specifically have provided initial results; however, the mechanism of action of these strategies is unclear. The data were requested from The Cancer Genome Atlas and Genotype-Tissue Expression, followed with the survival analysis and weighted gene co-expression network analysis to detect survival and stemness related genes. Patients were divided into three groups based on their immune status by applying single sample GSEA (ssGSEA) with proven dependability by ESTIMATE analysis. The filtered key genes were analyzed using oncomine, GEPIA, HPA, qRT-PCR, and functional analysis. Patients in a group with a higher stemness and a lower immune infiltration showed a worse overall survival probability, stemness and immune infiltration characteristics of breast cancer progressed in a non-linear fashion. Thirteen key genes related to stemness and immunity were identified and the functional analysis indicated their crucial roles in cell proliferation and immune escape strategies. The qRT-PCR results showed that the expression of PIMREG and MTFR2 differed in different stages of patients. Our study revealed a promising potential for CSC-target immunotherapy in the early stage of cancer and a probable value for PIMREG and MTFR2 as biomarkers and targets for immunotherapy.

Immunotherapy for targeting cancer stem cells in hepatocellular carcinoma

The rapid development and remarkable success of checkpoint inhibitors have provided significant breakthroughs in cancer treatment, including hepatocellular carcinoma (HCC). However, only 15-20% of HCC patients can benefit from checkpoint inhibitors. Cancer stem cells (CSCs) are responsible for recurrence, metastasis, and local and systemic therapy resistance in HCC. Accumulating evidence has suggested that HCC CSCs can create an immunosuppressive microenvironment through certain intrinsic and extrinsic mechanisms, resulting in immune evasion. Intrinsic evasion mechanisms mainly include activation of immune-related CSC signaling pathways, low-level expression of antigen presenting molecules, and high-level expression of immunosuppressive molecules. External evasion mechanisms are mainly related to HBV/HCV infection, alcoholic/nonalcoholic steatohepatitis, hypoxia stimulation, abnormal angiogenesis, and crosstalk between CSCs and immune cells. A better understanding of the complex mechanisms of CSCs involved in immune evasion will contribute to therapies for HCC. Here we will outline the detailed mechanisms of immune evasion for CSCs, and provide an overview of the current immunotherapies targeting CSCs in HCC.

Immunomodulatory effects of cytokine-induced expansion of cytotoxic lymphocytes in a mouse model of lupus-like disease

BACKGROUND AIMS

Certain therapies (e.g., daclizumab) that promote expansion of natural killer (NK) cells are associated with clinical amelioration of disease in the context of multiple sclerosis and associated mouse models. The clinical benefits are putatively attributable to an enhanced capacity of NK cells to kill activated pathogenic T cells. Whether a parallel approach will also be effective in systemic lupus erythematosus (lupus), a multi-organ autoimmune disease driven by aberrant responses of self-reactive T and B cells, is unclear.

METHODS

In the present study, the authors assess the therapeutic impact of IL-2- and IL-15-based strategies for expanding NK cells on measures of lupus-like disease in a mouse model.

RESULTS

Unexpectedly, cytokine-mediated expansion of cytotoxic lymphocytes aggravated immunological measures of lupus-like disease. Depletion studies revealed that the negative effects of these cytokine-based regimens can largely be attributed to expansion of CD8 T cells rather than NK cells.

CONCLUSIONS

These results provoke caution in the use of cytokine-based therapeutics to treat co-morbid cancers in patients with lupus and highlight the need for new methods to selectively expand NK cells to further assess their clinical value in autoimmune disease.

NKp30 - A prospective target for new cancer immunotherapy strategies

Natural killer (NK) cells are an important arm of the innate immune system. They constitutively express the NKp30 receptor. NKp30-mediated responses are triggered by the binding of specific ligands e.g. tumour cell-derived B7-H6 and involve the secretion of cytotoxic mediators including TNF-α, IFN-γ, perforins and granzymes. The latter two constitute a target cell-directed response that is critical in the process of immunosurveillance. The structure of NKp30 is presented, focusing on the ligand-binding site, on the ligand-induced structural changes and on the experimental data available correlating structure and binding affinity. The translation of NKp30 structural changes to disease progression is also reviewed. NKp30 role in immunotherapy has been explored in chimeric antigen receptor T-cell (CAR-T) therapy. However, antibodies or small ligands targeting NKp30 have not yet been developed. The data reviewed herein unveil the key structural aspects that must be considered for drug design in order to develop novel immunotherapy approaches.

NK cells-directed therapies target circulating tumor cells and metastasis

Metastasis is the major cause of cancer-related deaths. Invasive primary cancers often metastasize after circulating tumor cells (CTCs) enter the bloodstream or lymph node to colonize adjacent tissue or distant anatomical locations. CTCs interact with immune cells and metastatic microenvironments, survival signaling, and chemotherapeutic resistance. Among immune cells, natural killer (NK) cells can, directly and indirectly, interact with CTCs to control cancer metastasis. Understanding the molecular mechanisms that drive NK cells mediated recognition and elimination of CTCs may pave the way for a new generation of anti-CTC molecularly targeted immunotherapies. In this review, we will discuss i) the role of CTCs in metastases, ii) CTCs in the context of the tumor microenvironment, iii) CTCs immune escape, and finally, iv) the potentials of NK cell-based therapies alone, or in combination with nanomedicine for targeted-immunotherapies of metastatic diseases.

Anti-angiogenesis: Opening a new window for immunotherapy

The tumor microenvironment (TME) provides a guarantee for the survival and development of solid tumors. In recent years, treatment strategies for TME have set off a great upsurge in the field of cancer research. Tumor angiogenesis and tumor immune microenvironment are two important research branches of TME, and antiangiogenic therapy and immunotherapy have gradually become one important focus of cancer treatment research. More interestingly, increasing number of studies have indicated that there are complex regulatory interactions between the two treatment strategies, with multiple regulatory mechanisms involved. Based on these findings, clinical studies on the combination of immunotherapy and antiangiogenic therapy have also been carried out gradually. This combination strategy has shown good results in many types of tumors, but it also faces many challenges. The paper analysed the potential mechanism of the immunotherapy and antiangiogenic therapy combination, discussed the latest significant clinical trial progress and the existing challenges and problems, aiming to offer some available insights on the effective clinical application of this combination pattern.

An Integrative Analysis Reveals the Underlying Association Between CTNNB1 Mutation and Immunotherapy in Hepatocellular Carcinoma

Background: Tumor mutational burden (TMB) was verified to be closely associated with immune checkpoint inhibitors, but it is unclear whether gene mutation has an effect on immunotherapy of hepatocellular carcinoma (HCC). This research aimed to investigate the underlying correlation between gene mutation and immunotherapy in HCC. Methods: The somatic gene mutation data and gene expression data were retrieved from International Cancer Genome Consortium database and The Cancer Genome Atlas (TCGA) database. The mutational genes were selected by the intersection of three cohorts and further identified using survival analysis and TMB correlation analysis. After the identification of key mutational gene, we explored the correlation between gene mutation and both the immune cell infiltration and immune inhibitors. The signaling pathways associated with gene mutation were confirmed through gene set enrichment analysis. Furthermore, the survival analysis and mutational analysis based on TCGA cohort were performed for the validation of included gene. Results: As one of the frequently mutational genes in HCC, CTNNB1 was finally included in our research, for which it showed the significant result in survival analysis and the positive association with TMB of the three cohorts. Meanwhile, the validation of TCGA showed the significant results. Furthermore, natural killer (NK) cells and neutrophil were found to significantly infiltrate CTNNB1 mutation group from two cohorts. Besides, further analysis demonstrated that four types of immune inhibitors (CD96, HAVCR2, LGALS9, and TGFB1) were downregulated in CTNNB1 mutation group. Conclusion: Our research firstly revealed the underlying association between CTNNB1 mutation and immunotherapy, and we speculated that CTNNB1 mutation may modulate NK cells by affecting CD96. However, more functional experiments should be performed for verification.

Mesenchymal Stem Cells: A New Generation of Therapeutic Agents as Vehicles in Gene Therapy

In recent years, mesenchymal stem cells (MSCs) as a new tool for therapeutic gene delivery in clinics have attracted much attention. Their advantages cover longer lifespan, better isolation, and higher transfection efficiency and proliferation rate. MSCs are the preferred approach for cell-based therapies because of their in vitro self-renewal capacity, migrating especially to tumor tissues, as well as anti-inflammatory and immunomodulatory properties. Therefore, they have considerable efficiency in genetic engineering for future clinical applications in cancer gene therapy and other diseases. For improving therapeutic efficiency, targeted therapy of cancers can be achieved through the sustained release of therapeutic agents and functional gene expression induction to the intended tissues. The development of a new vector in gene therapy can improve the durability of a transgene expression. Also, the safety of the vector, if administered systemically, may resolve several problems, such as durability of expression and the host immune response. Currently, MSCs are prominent candidates as cell vehicles for both preclinical and clinical trials due to the secretion of therapeutic agents in several cancers. In the present study, we discuss the status of gene therapy in both viral and non-viral vectors along with their limitations. Throughout this study, the use of several nano-carriers for gene therapy is also investigated. Finally, we critically discuss the promising advantages of MSCs in targeted gene delivery, tumor inhibition and their utilization as the gene carriers in clinical situations.

Abscopal effect in radioimmunotherapy

Abscopal effect is an interesting phenomenon in radiobiology that causes activation of immune system against cancer cells. Traditionally, this phenomenon was known as a suppressor of non-irradiated tumors or metastasis. However, it can be used as a stimulator of the immune system against primary tumor during radiotherapy. Immunotherapy, a novel tumor therapy modality, also triggers immune system against cancer. To date, some immunotherapy types have been developed. However, immune checkpoint blockade is a more common modality and some drugs have been approved by the FDA. Studies have shown that radiotherapy or immunotherapy administered alone have low efficiency for tumor control. However, their combination has a more potent anti-tumor immunity. For this aim, it is important to induce abscopal effect in primary tumors, and also use appropriate drugs to target the mechanisms involved in the exhaustion of cytotoxic CD8+T lymphocytes (CTLs) and natural killer (NK) cells. Among the different radiotherapy techniques, stereotactic body radiation therapy (SBRT) with some few fractionations is the best choice for inducing abscopal effect. On the other hand, programmed cell death 1 (PD-1) is known as one of the best targets for triggering anti-tumor immunity. This combination is known as the best choice among various strategies for radioimmunotherapy. However, there is the need for other strategies to improve the duration of immune system's activity within tumor microenvironment (TME). In this review, we explain the cellular and molecular mechanisms behind abscopal effect by radiotherapy and evaluate the molecular targets which induce potent anti-tumor immunity.

New avenues for melanoma immunotherapy: Natural Killer cells?

Human solid malignant tumours may be particularly resistant to conventional therapies. Among solid tumours, immunological features of cutaneous melanoma have been well characterized in the past and today melanoma patients are routinely treated with the anti-immune checkpoints immunotherapy that has completely changed metastatic melanoma treatment and prognosis. Two cytotoxic cell populations may lead to the physical elimination of tumour cell targets: cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. Tumour recognition by CTLs depends on major histocompatibility complex (MHC) class I molecules, while NK cells recognize tumours expressing low or null levels of MHC class I molecules. Despite this well-established complementarity, NK cells are still left behind in the optimization of innovative immunotherapy approaches. NK cells are members of innate lymphoid cells (ILCs) that play a critical role in early host defence against invading pathogens and transformed cells. Recent findings suggest that NK cell frequencies directly correlate with the overall survival of ipilimumab-treated melanoma patients. Furthermore, in vitro and in vivo evidences indicate that NK cells can selectively kill cancer stem cells, reducing tumour size and delaying metastatic progression. The aim of this review is to provide a survey of the evidences indicating NK cells as an excellent candidate to complement the newest solid tumour immunotherapy approaches.

Non-clinical efficacy, safety and stable clinical cell processing of induced pluripotent stem cell-derived anti-glypican-3 chimeric antigen receptor-expressing natural killer/innate lymphoid cells

The use of allogeneic, pluripotent stem‐cell‐derived immune cells for cancer immunotherapy has been the subject of recent clinical trials. In Japan, investigator‐initiated clinical trials will soon begin for ovarian cancer treatment using human leukocyte antigen (HLA)‐homozygous‐induced pluripotent stem cell (iPSC)‐derived anti–glypican‐3 (GPC3) chimeric antigen receptor (CAR)‐expressing natural killer/innate lymphoid cells (NK/ILC). Using pluripotent stem cells as the source for allogeneic immune cells facilitates stringent quality control of the final product, in terms of efficacy, safety and producibility. In this paper, we describe our methods for the stable, feeder‐free production of CAR‐expressing NK/ILC cells from CAR‐transduced iPSC with clinically relevant scale and materials. The average number of cells that could be differentiated from 1.8‐3.6 × 10⁶ iPSC within 7 weeks was 1.8‐4.0 × 10⁹. These cells showed stable CD45/CD7/CAR expression, effector functions of cytotoxicity and interferon gamma (IFN‐γ) production against GPC3‐expressing tumor cells. When the CAR‐NK/ILC cells were injected into a GPC3‐positive, ovarian‐tumor‐bearing, immunodeficient mouse model, we observed a significant therapeutic effect that prolonged the survival of the animals. When the cells were injected into immunodeficient mice during non–clinical safety tests, no acute systemic toxicity or tumorigenicity of the final product or residual iPSC was observed. In addition, our test results for the CAR‐NK/ILC cells generated with clinical manufacturing standards are encouraging, and these methods should accelerate the development of allogeneic pluripotent stem cell‐based immune cell cancer therapies.

Immune cell engineering: opportunities in lung cancer therapeutics

Engineered immune cells offer a prime therapeutic alternate for some aggressive and frequently occurring malignancies like lung cancer. These therapies were reported to result in tumor regression and overall improvement in patient survival. However, studies also suggest that the presence of cancer cell-induced immune-suppressive microenvironment, off-target toxicity, and difficulty in concurrent imaging are some prime impendent in the success of these approaches. The present article reviews the need and significance of the currently available immune cell-based strategies for lung cancer therapeutics. It also showcases the utility of incorporating nanoengineered strategies and details the available formulations of nanocarriers. In last, it briefly discussed the existing methods for nanoparticle fuctionalization and challenges in translating basic research to the clinics. Graphical Abstract.

EP300 mutation is associated with tumor mutation burden and promotes antitumor immunity in bladder cancer patients

Bladder cancer is a leading cause of morbidity and mortality worldwide. Currently, immunotherapy has become a worthwhile therapy for bladder cancer. Tumor mutation burden (TMB) has been regarded as the most prevalent biomarker to predict immunotherapy. Bladder cancer is reported to have the third highest mutation rate. However, whether these gene mutations are related to TMB and immune response remain unknown. In this study, we downloaded somatic mutation data of bladder cancer from The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) datasets, and found 11 frequently mutated genes were covered by both two cohorts including FGFR3, TTN, XIRP2, CREBBP, PIK3CA, TP53, MUC16, EP300 (E1A binding protein P300), ARID1A, ERBB2, and KDM6A. Among them, EP300 mutation was associated with higher TMB and indicated a favorable clinical prognosis. Furthermore, based on Gene set enrichment analysis (GSEA) and CIBERSORT algorithm, we observed that EP300 mutation upregulated signaling pathways involved in immune system and enhanced antitumor immune response. In conclusion, EP300 is frequently mutated in bladder cancer, and its mutation is associated with increased TMB and promotes antitumor immunity, which may serve as a biomarker to predict immune response.

Mesenchymal stem cells as carrier of the therapeutic agent in the gene therapy of blood disorders

Nonhematopoietic stem cells as a delivery platform of therapeutic useful genes have attracted widespread attention in recent years, owing to gained a long lifespan, easy separation, high proliferation, and high transfection capacity. Mesenchymal stem/stromal cells (MSCs) are the choice of the cells for gene and cell therapy due to high self-renewal capacity, high migration rate to the site of the tumor, and with immune suppressive and anti-inflammatory properties. Hence, it has a high potential of safety genetic modification of MSCs for antitumor gene expression and has paved the way for the clinical application of these cells to target the therapy of cancers and other diseases. The aim of gene therapy is targeted treatment of cancers and diseases through recovery, change, or enhancement cell performance to the sustained secretion of useful therapeutic proteins and induction expression of the functional gene in intended tissue. Recent developments in the vectors designing leading to the increase and durability of expression and improvement of the safety of the vectors that overcome a lot of problems, such as durability of expression and the host immune response. Nowadays, gene therapy approach is used by MSCs as a delivery vehicle in the preclinical and the clinical trials for the secretion of erythropoietin, recombinant antibodies, coagulation factors, cytokines, as well as angiogenic inhibitors in many blood disorders like anemia, hemophilia, and malignancies. In this study, we critically discuss the status of gene therapy by MSCs as a delivery vehicle for the treatment of blood disorders. Finally, the results of clinical trial studies are assessed, highlighting promising advantages of this emerging technology in the clinical setting.

Medulloblastoma rendered susceptible to NK-cell attack by TGFβ neutralization

BACKGROUND

Medulloblastoma (MB), the most common pediatric brain cancer, presents with a poor prognosis in a subset of patients with high risk disease, or at recurrence, where current therapies are ineffective. Cord blood (CB) natural killer (NK) cells may be promising off-the-shelf effector cells for immunotherapy due to their recognition of malignant cells without the need for a known target, ready availability from multiple banks, and their potential to expand exponentially. However, they are currently limited by immune suppressive cytokines secreted in the MB tumor microenvironment including Transforming Growth Factor β (TGF-β). Here, we address this challenge in in vitro models of MB.

METHODS

CB-derived NK cells were modified to express a dominant negative TGF-β receptor II (DNRII) using retroviral transduction. The ability of transduced CB cells to maintain function in the presence of medulloblastoma-conditioned media was then assessed.

RESULTS

We observed that the cytotoxic ability of nontransduced CB-NK cells was reduced in the presence of TGF-β-rich, medulloblastoma-conditioned media (21.21 ± 1.19% killing at E:T 5:1 in the absence vs. 14.98 ± 2.11% in the presence of medulloblastoma-conditioned media, n = 8, p = 0.02), but was unaffected in CB-derived DNRII-transduced NK cells (21.11 ± 1.84% killing at E:T 5:1 in the absence vs. 21.81 ± 3.37 in the presence of medulloblastoma-conditioned media, n = 8, p = 0.85. We also observed decreased expression of CCR2 in untransduced NK cells (mean CCR2 MFI 826 ± 117 in untransduced NK + MB supernatant from mean CCR2 MFI 1639.29 ± 215 in no MB supernatant, n = 7, p = 0.0156), but not in the transduced cells. Finally, we observed that CB-derived DNRII-transduced NK cells may protect surrounding immune cells by providing a cytokine sink for TGF-β (decreased TGF-β levels of 610 ± 265 pg/mL in CB-derived DNRII-transduced NK cells vs. 1817 ± 342 pg/mL in untransduced cells; p = 0.008).

CONCLUSIONS

CB NK cells expressing a TGF-β DNRII may have a functional advantage over unmodified NK cells in the presence of TGF-β-rich MB, warranting further investigation on its potential applications for patients with medulloblastoma.

NK-Cell-Encapsulated Porous Microspheres via Microfluidic Electrospray for Tumor Immunotherapy

Immunotherapy has recently garnered significant research interest in the field of clinical cancer management. The potential of tumor immunotherapy has been demonstrated for targeting a variety of tumors, both in vivo and in vitro, yielding some remarkable therapeutic effects. Herein, inspired by the stem cell niche, we developed a scale-up approach to generating porous microspheres with encapsulated natural killer (NK) cells via microfluidic electrospray for in situ tumor immunotherapy. The generated microspheres contained porous microstructures with tunable morphologies because of versatile but precise fluid control in the microfluidic electrospray system. NK-92MI cells encapsulated in porous microspheres were protected from the outer complex environment, allowing for improved proliferation and functionality. As observed, perforin and granzymes were sustainably secreted from the encapsulated NK-92MI cells, which exhibited robust killing effects on tumors both in vitro and in vivo. With continual proliferation, NK-92MI cells budded from the surface of porous microspheres and migrated into the surrounding residual tumor tissues, further destroying tumor cells. More importantly, no side effects owing to the native host immune system were observed by injecting the NK-92MI cell-encapsulated microspheres into tumors in vivo. Therefore, the NK-cell-encapsulated porous microspheres show great potential for tumor immunotherapy, offering a robust and attractive treatment option for cancer patient management.

Role of physical exercise in the regulation of epigenetic mechanisms in inflammation, cancer, neurodegenerative diseases, and aging process

The genetic heritage for decades has been considered to respond only to gene promoters or suppressors, with specific roles for oncogenes or tumor-suppressor genes. Epigenetics is progressively attracting increasing interest because it has demonstrated the capacity of these regulatory processes to regulate the gene expression without modifying gene sequence. Several factors may influence epigenetics, such as lifestyles including food selection. A role for physical exercise is emerging in the epigenetic regulation of gene expression. In this review, we resume physiological and pathological implications of epigenetic modification induced by the physical activity (PA). Inflammation and cancer mechanisms, immune system, central nervous system, and the aging process receive benefits due to PA through epigenetic mechanisms. Thus, the modulation of epigenetic processes by physical exercise positively influences prevention, development, and the course of inflammatory and cancer diseases, as well as neurodegenerative illnesses. This growing field of studies gives rise to a new role for PA as an option in prevention strategies and to integrate pharmacological therapeutic treatments.

Natural killer cells: a review of biology, therapeutic potential and challenges in treatment of solid tumors

Natural killer (NK) cells lead immune surveillance against cancer and early elimination of small tumors. Owing to their ability to engage tumor targets without the need of specific antigen, the therapeutic potential of NK cells has been extensively explored in hematological malignancies. In solid tumors, however, their role in the clinical arena remains poorly exploited despite a broad accumulation of preclinical data. In this article, we review our current knowledge of NK cells’ biology, and highlight the challenges facing NK cell antitumor strategies in solid tumors. We further summarize the abundant preclinical attempts at overcoming these challenges, present past and ongoing clinical trial data and finally discuss the potential impact of novel insights on the development of NK cell-based therapies.

Cancer stem cell immunology and immunotherapy: Harnessing the immune system against cancer's source

Despite recent advances in diagnosis and therapy having improved cancer outcome, many patients still do not respond to treatments, resulting in the progression or relapse of the disease, eventually impairing survival expectations. The limited efficacy of therapy is often attributable to its inability to affect cancer stem cells (CSCs), a small population of cells resistant to current radio- and chemo-therapies. CSCs are characterized by self-renewal and tumor-initiating capabilities, and function as a reservoir for the local and distant recurrence of the disease. Therefore, new therapeutic approaches able to effectively target and deplete CSCs are urgently needed. Immunotherapy is facing a renewed interest for its potential in cancer treatment, and the possibility of harnessing the immune system to target CSCs is being addressed by a new exciting research field. In this chapter, we discuss the cancer stem cell model and illustrate CSC biological and molecular properties, critically addressing theoretical and practical issues linked with their definition and study. We then review the existing literature regarding the immunological properties of CSCs and the complex interplay occurring between CSCs and immune cells. Finally, we present up-to-date studies on CSC immunotargeting and its potential future perspective. In conclusion, understanding the interplay between CSC biology and tumor immunology will provide a deeper understanding of the mechanisms that regulate CSC immunological properties. This will contribute to the design of new CSC-directed immunotherapeutic strategies with the potential of strongly improving cancer outcomes.

Development of innate immune cells from human pluripotent stem cells

Mouse and human pluripotent stem cells have been widely used to study the development of the hematopoietic and immune systems. Although not all cells can be derived with the same efficiency, immune cells such as natural killer (NK) cells and macrophages can be easily produced from PSCs to enable development of new cell-based therapies. NK cells and macrophages are part of the innate immune system, the first line of defense against malignancies and infectious disease. Human embryonic stem cell (hESC)- and induced pluripotent stem cell (iPSC)-derived NK cells can be produced at a clinical scale suitable for translation into clinical trials. Additionally, PSCs can be genetically modified to produce hESC/iPSC-derived human NK cells with enhanced antitumor activity. These engineered NK cells can express a stabilized version of the high-affinity Fc receptor CD16, chimeric antigen receptors, or other strategies to enable more potent and targeted cellular immunotherapies. Moreover, macrophages can also be routinely and efficiently produced from hESCs and iPSCs as a tool to expand our knowledge of the basic biology of these cells. hESC- and iPSC-derived macrophages can also be employed as a novel approach for cancer immunotherapy, as well as a strategy to repair or regenerate diseased and damaged tissues and organs.