Systemic IL-15 promotes allogeneic cell rejection in patients treated with natural killer cell adoptive therapy

Developing oxaliplatin and IL-15 Co-carried gels as drug depots to enable triple-interlocked combination therapy for colorectal cancer

Chemo-immunotherapy, which involves the simultaneous use of chemotherapy drug and immunotherapeutic agent to achieve synergistic effects, plays a crucial role in cancer treatment. However, the immunosuppressive microenvironment, insufficient tumor specificity, and serious systemic side effects hinder their synergistic therapeutic effects and clinical applications. Herein, T cell and natural killer (NK) cell, which are the most important immune effector cells, were both activated to reverse the immunosuppressive microenvironment. To simplify drug carriers, oxaliplatin was selected as the chemotherapy drug which can both induce the ICD effect and activate T cells. IL-15 was selected to activate NK cells. To enhance the productivity of the carrier and reduce side effects, the easy-prepared thermosensitive hydrogel (OXL/IL-15 TG) was developed to co-load oxaliplatin-loaded liposomes (OXL) and IL-15. Colorectal cancer, suitable for in situ administration, was selected as model cancer. The resulting novel triple-interlocked combination therapy could directly kill the tumor cells, induces ICD effect and activate NK cells. After administration, OXL/IL-15 TG was formed serving as a drug depot, slowing releasing OXL and IL-15 non-interferencely. OXL around 165.47±7.04 nm was passively delivered to tumor tissue, killing tumor cells and inducing ICD effect. The results demonstrated that IL-15 stimulated the activation of NK cells. In tumor-bearing mice models, OXL/IL-15 TG exhibited a remarkable and noteworthy anti-tumor efficacy, and expanded survival rate. Notably, OXL/IL-15 TG led to an enhanced infiltration of CD3+CD8+ T cells and CD3-CD49+ NK cells within the tumor tissue. Overall, the triple-interlocked combination therapy provided a new idea for colorectal cancer therapy.

Enhancing Therapeutic Efficacy of FLT3 Inhibitors with Combination Therapy for Treatment of Acute Myeloid Leukemia

FMS-like tyrosine kinase 3 (FLT3) mutations are genetic changes found in approximately thirty percent of patients with acute myeloid leukemia (AML). FLT3 mutations in AML represent a challenging clinical scenario characterized by a high rate of relapse, even after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The advent of FLT3 tyrosine kinase inhibitors (TKIs), such as midostaurin and gilteritinib, has shown promise in achieving complete remission. However, a substantial proportion of patients still experience relapse following TKI treatment, necessitating innovative therapeutic strategies. This review critically addresses the current landscape of TKI treatments for FLT3+ AML, with a particular focus on gilteritinib. Gilteritinib, a highly selective FLT3 inhibitor, has demonstrated efficacy in targeting the mutant FLT3 receptor, thereby inhibiting aberrant signaling pathways that drive leukemic proliferation. However, monotherapy with TKIs may not be sufficient to eradicate AML blasts. Specifically, we provide evidence for integrating gilteritinib with mammalian targets of rapamycin (mTOR) inhibitors and interleukin-15 (IL-15) complexes. The combination of gilteritinib, mTOR inhibitors, and IL-15 complexes presents a compelling strategy to enhance the eradication of AML blasts and enhance NK cell killing, offering a potential for improved patient outcomes.

Delivery Systems Developed for Treatment Combinations to Improve Adoptive Cell Therapy

Adoptive cell therapy (ACT) has shown great success in the clinic for treating hematologic malignancies. However, solid tumor treatment with ACT monotherapy is still challenging, owing to insufficient expansion and rapid exhaustion of adoptive cells, tumor antigen downregulation/loss, and dense tumor extracellular matrix. Delivery strategies for combination cell therapy have great potential to overcome these hurdles. The delivery of vaccines, immune checkpoint inhibitors, cytokines, chemotherapeutics, and photothermal reagents in combination with adoptive cells, have been shown to improve the expansion/activation, decrease exhaustion, and promote the penetration of adoptive cells in solid tumors. Moreover, the delivery of nucleic acids to engineer immune cells directly in vivo holds promise to overcome many of the hurdles associated with the complex ex vivo cell engineering strategies. Here, these research advance, as well as the opportunities and challenges for integrating delivery technologies into cell therapy s are discussed, and the outlook for these emerging areas are criticlly analyzed.

Traversing the bench to bedside journey for iNKT cell therapies

Invariant natural killer T (iNKT) cells are immune cells that harness properties of both the innate and adaptive immune system and exert multiple functions critical for the control of various diseases. Prevention of graft-versus-host disease (GVHD) by iNKT cells has been demonstrated in mouse models and in correlative human studies in which high iNKT cell content in the donor graft is associated with reduced GVHD in the setting of allogeneic hematopoietic stem cell transplants. This suggests that approaches to increase the number of iNKT cells in the setting of an allogeneic transplant may reduce GVHD. iNKT cells can also induce cytolysis of tumor cells, and murine experiments demonstrate that activating iNKT cells in vivo or treating mice with ex vivo expanded iNKT cells can reduce tumor burden. More recently, research has focused on testing anti-tumor efficacy of iNKT cells genetically modified to express a chimeric antigen receptor (CAR) protein (CAR-iNKT) cells to enhance iNKT cell tumor killing. Further, several of these approaches are now being tested in clinical trials, with strong safety signals demonstrated, though efficacy remains to be established following these early phase clinical trials. Here we review the progress in the field relating to role of iNKT cells in GVHD prevention and anti- cancer efficacy. Although the iNKT field is progressing at an exciting rate, there is much to learn regarding iNKT cell subset immunophenotype and functional relationships, optimal ex vivo expansion approaches, ideal treatment protocols, need for cytokine support, and rejection risk of iNKT cells in the allogeneic setting.

Human NK cells and cancer

The long story of NK cells started about 50 y ago with the first demonstration of a natural cytotoxic activity within an undefined subset of circulating leukocytes, has involved an ever-growing number of researchers, fascinated by the apparently easy-to-reach aim of getting a "universal anti-tumor immune tool". In fact, in spite of the impressive progress obtained in the first decades, these cells proved far more complex than expected and, paradoxically, the accumulating findings have continuously moved forward the attainment of a complete control of their function for immunotherapy. The refined studies of these latter years have indicated that NK cells can epigenetically calibrate their functional potential, in response to specific environmental contexts, giving rise to extraordinarily variegated subpopulations, comprehensive of memory-like cells, tissue-resident cells, or cells in various differentiation stages, or distinct functional states. In addition, NK cells can adapt their activity in response to a complex body of signals, spanning from the interaction with either suppressive or stimulating cells (myeloid-derived suppressor cells or dendritic cells, respectively) to the engagement of various receptors (specific for immune checkpoints, cytokines, tumor/viral ligands, or mediating antibody-dependent cell-mediated cytotoxicity). According to this picture, the idea of an easy and generalized exploitation of NK cells is changing, and the way is opening toward new carefully designed, combined and personalized therapeutic strategies, also based on the use of genetically modified NK cells and stimuli capable of strengthening and redirecting their effector functions against cancer.

Targeting CD8+ T cells with natural products for tumor therapy: Revealing insights into the mechanisms

BACKGROUND

Despite significant advances in cancer immunotherapy over the past decades, such as T cell-engaging chimeric antigen receptor (CAR)-T cell therapy and immune checkpoint blockade (ICB), therapeutic failure resulting from various factors remains prevalent. Therefore, developing combinational immunotherapeutic strategies is of great significance for improving the clinical outcome of cancer immunotherapy. Natural products are substances that naturally exist in various living organisms with multiple pharmacological or biological activities, and some of them have been found to have anti-tumor potential. Notably, emerging evidences have suggested that several natural compounds may boost the anti-tumor effects through activating immune response of hosts, in which CD8+ T cells play a pivotal role.

METHODS

The data of this review come from PubMed, Web of Science, Google Scholar, and ClinicalTrials (https://clinicaltrials.gov/) with the keywords "CD8+ T cell", "anti-tumor", "immunity", "signal 1", "signal 2", "signal 3", "natural products", "T cell receptor (TCR)", "co-stimulation", "co-inhibition", "immune checkpoint", "inflammatory cytokine", "hesperidin", "ginsenoside", "quercetin", "curcumin", "apigenin", "dendrobium officinale polysaccharides (DOPS)", "luteolin", "shikonin", "licochalcone A", "erianin", "resveratrol", "procyanidin", "berberine", "usnic acid", "naringenin", "6-gingerol", "ganoderma lucidum polysaccharide (GL-PS)", "neem leaf glycoprotein (NLGP)", "paclitaxel", "source", "pharmacological activities", and "toxicity". These literatures were published between 1993 and 2023.

RESULTS

Natural products have considerable advantages as anti-tumor drugs based on the various species, wide distribution, low price, and few side effects. This review summarized the effects and mechanisms of some natural products that exhibit anti-tumor effects via targeting CD8+ T cells, mainly focused on the three signals that activate CD8+ T cells: TCR, co-stimulation, and inflammatory cytokines.

CONCLUSION

Clarifying the role and underlying mechanism of natural products in cancer immunotherapy may provide more options for combinational treatment strategies and benefit cancer therapy, to shed light on identifying potential natural compounds for improving the clinical outcome in cancer immunotherapy.

Harnessing the potential of hydrogels for advanced therapeutic applications: current achievements and future directions

The applications of hydrogels have expanded significantly due to their versatile, highly tunable properties and breakthroughs in biomaterial technologies. In this review, we cover the major achievements and the potential of hydrogels in therapeutic applications, focusing primarily on two areas: emerging cell-based therapies and promising non-cell therapeutic modalities. Within the context of cell therapy, we discuss the capacity of hydrogels to overcome the existing translational challenges faced by mainstream cell therapy paradigms, provide a detailed discussion on the advantages and principal design considerations of hydrogels for boosting the efficacy of cell therapy, as well as list specific examples of their applications in different disease scenarios. We then explore the potential of hydrogels in drug delivery, physical intervention therapies, and other non-cell therapeutic areas (e.g., bioadhesives, artificial tissues, and biosensors), emphasizing their utility beyond mere delivery vehicles. Additionally, we complement our discussion on the latest progress and challenges in the clinical application of hydrogels and outline future research directions, particularly in terms of integration with advanced biomanufacturing technologies. This review aims to present a comprehensive view and critical insights into the design and selection of hydrogels for both cell therapy and non-cell therapies, tailored to meet the therapeutic requirements of diverse diseases and situations.

Death receptors 4/5 mediate tumour sensitivity to natural killer cell-mediated cytotoxicity in mismatch repair deficient colorectal cancer

BACKGROUND

Identifying the target of natural killer (NK) cells in colorectal cancer (CRC) is critical for optimising the clinical use of NK cell-mediated immunotherapy. Mismatch repair deficiency (dMMR) is associated with high immune cell infiltration and MHC Class I defects. Whether dMMR CRC responses to NK cell therapy remains unclear.

METHODS

MLH1, DR4, and DR5 knockout cell lines were established using CRISPR-Cas9 system. NK92-MI or NK cell isolated from BABL/C mice were used as effector cells against tumour cells. Inflammatory cytokines secretion by CRC cells was assessed via cytokine analysis. NK-cell-deficient/proficient animal models were used to validate the NK cell sensitivity.

RESULTS

We observed that dMMR CRC cells were more sensitive to NK cell-mediated cytotoxicity than were mismatch-repair-proficient (pMMR) CRC cells. In dMMR CRC, Death receptor (DR)4/5 was upregulated and mediated sensitivity to NK cell-mediated cytotoxicity. DR4/5-mediated secretion of interleukin -12 sustained NK cell viability in dMMR CRC. NK cell depletion induced dMMR CRC tumour growth, and NK cell transfer inhibited lung metastasis of dMMR CRC with DR4/5 expression in vivo. TP53 upregulated DR4/DR5 expression in dMMR CRC.

CONCLUSIONS

dMMR associated with increased sensitivity to NK cell-mediated cytotoxicity in CRC. DR4/DR5 sensitise dMMR CRC to NK cell-mediated cytotoxicity.

Efficiently targeting neuroblastoma with the combination of anti-ROR1 CAR NK cells and N-803 in vitro and in vivo in NB xenografts

The prognosis for children with recurrent and/or refractory neuroblastoma (NB) is dismal. The receptor tyrosine kinase-like orphan receptor 1 (ROR1), which is highly expressed on the surface of NB cells, provides a potential target for novel immunotherapeutics. Anti-ROR1 chimeric antigen receptor engineered ex vivo expanded peripheral blood natural killer (anti-ROR1 CAR exPBNK) cells represent this approach. N-803 is an IL-15 superagonist with enhanced biological activity. In this study, we investigated the in vitro and in vivo anti-tumor effects of anti-ROR1 CAR exPBNK cells with or without N-803 against ROR1+ NB models. Compared to mock exPBNK cells, anti-ROR1 CAR exPBNK cells had significantly enhanced cytotoxicity against ROR1+ NB cells, and N-803 further increased cytotoxicity. High-dimensional analysis revealed that N-803 enhanced Stat5 phosphorylation and Ki67 levels in both exPBNK and anti-ROR1 CAR exPBNK cells with or without NB cells. In vivo, anti-ROR1 CAR exPBNK plus N-803 significantly (p < 0.05) enhanced survival in human ROR1+ NB xenografted NSG mice compared to anti-ROR1 CAR exPBNK alone. Our results provide the rationale for further development of anti-ROR1 CAR exPBNK cells plus N-803 as a novel combination immunotherapeutic for patients with recurrent and/or refractory ROR1+ NB.

CD70-specific CAR NK cells expressing IL-15 for the treatment of CD19-negative B-cell malignancy

ABSTRACT

Chimeric antigen receptor (CAR) natural killer (NK) cells can eliminate tumors not only through the ability of the CAR molecule to recognize antigen-expressed cancer cells but also through NK-cell receptors themselves. This overcomes some of the limitations of CAR T cells, paving the way for CAR NK cells for safer and more effective off-the-shelf cellular therapy. In this study, CD70-specific (a pan-target of lymphoma) fourth-generation CAR with 4-1BB costimulatory domain and interleukin-15 (IL-15) was constructed and transduced into cord blood-derived NK cells by Baboon envelope pseudotyped lentiviral vector. CD70-CAR NK cells displayed superior cytotoxic activity in vitro and in vivo against CD19-negative B-cell lymphoma when compared with nontransduced NK cells and CD19-specific CAR NK cells. Importantly, mice that received 2 doses of CD70-CAR NK cells showed effective eradication of tumors, accompanied by increased concentration of plasma IL-15 and enhanced CAR NK cell proliferation and persistence. Our study suggests that repetitive administration-based CAR NK-cell therapy has clinical advantage compared with a single dose of CAR NK cells for the treatment of B-cell lymphoma.

Potential biomarkers for immune monitoring after renal transplantation

Renal transplantation represents the foremost efficacious approach for ameliorating end-stage renal disease. Despite the current state of advanced renal transplantation techniques and the established postoperative immunosuppression strategy, a subset of patients continues to experience immune rejection during both the early and late postoperative phases, ultimately leading to graft loss. Consequently, the identification of immunobiomarkers capable of predicting the onset of immune rejection becomes imperative in order to facilitate early intervention strategies and enhance long-term prognoses. Upon reviewing the pertinent literature, we identified several indicators that could potentially serve as immune biomarkers to varying extents. These include the T1/T2 ratio, Treg/Th17 ratio, IL-10/TNF-α ratio, IL-33, IL-34, IL-6, IL-4, other cytokines, and NOX2/4.

Spatiotemporal-Controlled NIR-II Immune Agonist Sensitizes Cancer Immunotherapy

The integration of nanomedicine and immunotherapy has presented a promising opportunity for the treatment of cancer and diverse diseases. However, achieving spatiotemporal controllable immunotherapy with excellent efficacy and safety performances remains a significant challenge. This study develops a biodegradable near-infrared II (NIR-II) photothermal response polymer nanoparticle (PTEQ) system. This platform exhibits intrinsic immunostimulatory properties while concurrently delivering siRNA for Programmed Death-Ligand 1 (siPD-L1), leveraging enhanced immune responses and immune checkpoint blockade for safe and effective cancer therapy. In the CT26 tumor-bearing mouse model, PTEQ, as an immune stimulant, significantly boosts the infiltration of CD4+ and CD8+ T cells within the tumor microenvironment (TME). The PTEQ/siPD-L1+laser group not only initiates NIR-II photothermal therapy but also promotes the activation and infiltration of T cells, M1 macrophage polarization, and maturation of dendritic cells in the TME, resulting in the complete elimination of tumors in 7/10 cases, achieving a 100% survival rate. In another in vivo vaccine experiment, all tumors on the right side are completely eliminated in the PTEQ/siPD-L1+laser group, reaching a 100% tumor eradication rate. These findings underscore the potential of this strategy to overcome the current immunotherapeutic limitations and achieve immune therapy normalization.

Targeting the innate immune system in pediatric and adult AML

While the introduction of T cell-based immunotherapies has improved outcomes in many cancer types, the development of immunotherapies for both adult and pediatric AML has been relatively slow and limited. In addition to the need to identify suitable target antigens, a better understanding of the immunosuppressive tumor microenvironment is necessary for the design of novel immunotherapy approaches. To date, most immune characterization studies in AML have focused on T cells, while innate immune lineages such as monocytes, granulocytes and natural killer (NK) cells, received less attention. In solid cancers, studies have shown that innate immune cells, such as macrophages, myeloid-derived suppressor cells and neutrophils are highly plastic and may differentiate into immunosuppressive cells depending on signals received in their microenvironment, while NK cells appear to be functionally impaired. Hence, an in-depth characterization of the innate immune compartment in the TME is urgently needed to guide the development of immunotherapeutic interventions for AML. In this review, we summarize the current knowledge on the innate immune compartment in AML, and we discuss how targeting its components may enhance T cell-based- and other immunotherapeutic approaches.

Inflammatory response in traumatic brain and spinal cord injury: The role of XCL1-XCR1 axis and T cells

BACKGROUND

Traumatic brain injury (TBI) and spinal cord injury (SCI) are acquired injuries to the central nervous system (CNS) caused by external forces that cause temporary or permanent sensory and motor impairments and the potential for long-term disability or even death. These conditions currently lack effective treatments and impose substantial physical, social, and economic burdens on millions of people and families worldwide. TBI and SCI involve intricate pathological mechanisms, and the inflammatory response contributes significantly to secondary injury in TBI and SCI. It plays a crucial role in prolonging the post-CNS trauma period and becomes a focal point for a potential therapeutic intervention. Previous research on the inflammatory response has traditionally concentrated on glial cells, such as astrocytes and microglia. However, increasing evidence highlights the crucial involvement of lymphocytes in the inflammatory response to CNS injury, particularly CD8+ T cells and NK cells, along with their downstream XCL1-XCR1 axis.

OBJECTIVE

This review aims to provide an overview of the role of the XCL1-XCR1 axis and the T-cell response in inflammation caused by TBI and SCI and identify potential targets for therapy.

METHODS

We conducted a comprehensive search of PubMed and Web of Science using relevant keywords related to the XCL1-XCR1 axis, T-cell response, TBI, and SCI.

RESULTS

This study examines the upstream and downstream pathways involved in inflammation caused by TBI and SCI, including interleukin-15 (IL-15), interleukin-12 (IL-12), CD8+ T cells, CD4+ T cells, NK cells, XCL1, XCR1+ dendritic cells, interferon-gamma (IFN-γ), helper T0 cells (Th0 cells), helper T1 cells (Th1 cells), and helper T17 cells (Th17 cells). We describe their proinflammatory effect in TBI and SCI.

CONCLUSIONS

The findings suggest that the XCL1-XCR1 axis and the T-cell response have great potential for preclinical investigations and treatments for TBI and SCI.

IL-15 as a key regulator in NK cell-mediated immunotherapy for cancer: From bench to bedside

Interleukin 15 (IL-15) has emerged as a crucial factor in the relationship between natural killer (NK) cells and immunotherapy for cancer. This review article aims to provide a comprehensive understanding of the role of IL-15 in NK cell-mediated immunotherapy. First, the key role of IL-15 signaling in NK cell immunity is discussed, highlighting its regulation of NK cell functions and antitumor properties. Furthermore, the use of IL-15 or its analogs in clinical trials as a therapeutic strategy for various cancers, including the genetic modification of NK cells to produce IL-15, has been explored. The potential of IL-15-based therapies, such as chimeric antigen receptor (CAR) T and NK cell infusion along with IL-15 in combination with checkpoint inhibitors and other treatments, has been examined. This review also addresses the challenges and advantages of incorporating IL-15 in cell-based immunotherapy. Additionally, unresolved questions regarding the detection and biological significance of the soluble IL-15/IL-15Rα complex, as well as the potential role of IL-15/IL-15Rα in human cancer and the immunological consequences of prolonged exposure to soluble IL-15 for NK cells, are discussed.

Induced CD8α identifies human NK cells with enhanced proliferative fitness and modulates NK cell activation

The surface receptor CD8α is present on 20%-80% of human (but not mouse) NK cells, yet its function on NK cells remains poorly understood. CD8α expression on donor NK cells was associated with a lack of therapeutic responses in patients with leukemia in prior studies, thus, we hypothesized that CD8α may affect critical NK cell functions. Here, we discovered that CD8α- NK cells had improved control of leukemia in xenograft models compared with CD8α+ NK cells, likely due to an enhanced capacity for proliferation. Unexpectedly, we found that CD8α expression was induced on approximately 30% of previously CD8α- NK cells following IL-15 stimulation. These induced CD8α+ (iCD8α+) NK cells had the greatest proliferation, responses to IL-15 signaling, and metabolic activity compared with those that sustained existing CD8α expression (sustained CD8α+) or those that remained CD8α- (persistent CD8α-). These iCD8α+ cells originated from an IL-15Rβhi NK cell population, with CD8α expression dependent on the transcription factor RUNX3. Moreover, CD8A CRISPR/Cas9 deletion resulted in enhanced responses through the activating receptor NKp30, possibly by modulating KIR inhibitory function. Thus, CD8α status identified human NK cell capacity for IL-15-induced proliferation and metabolism in a time-dependent fashion, and its presence had a suppressive effect on NK cell-activating receptors.

Development of NK cell-based cancer immunotherapies through receptor engineering

Natural killer (NK) cell-based immunotherapies are attracting increasing interest in the field of cancer treatment. Early clinical trials have shown promising outcomes, alongside satisfactory product efficacy and safety. Recent developments have greatly increased the therapeutic potential of NK cells by endowing them with enhanced recognition and cytotoxic capacities. This review focuses on surface receptor engineering in NK cell therapy and discusses its impact, challenges, and future directions.Most approaches are based on engineering with chimeric antigen receptors to allow NK cells to target specific tumor antigens independent of human leukocyte antigen restriction. This approach has increased the precision and potency of NK-mediated recognition and elimination of cancer cells. In addition, engineering NK cells with T-cell receptors also mediates the recognition of intracellular epitopes, which broadens the range of target peptides. Indirect tumor peptide recognition by NK cells has also been improved by optimizing immunoglobulin constant fragment receptor expression and signaling. Indeed, engineered NK cells have an improved ability to recognize and destroy target cells coated with specific antibodies, thereby increasing their antibody-dependent cellular cytotoxicity. The ability of NK cell receptor engineering to promote the expansion, persistence, and infiltration of transferred cells in the tumor microenvironment has also been explored. Receptor-based strategies for sustained NK cell functionality within the tumor environment have also been discussed, and these strategies providing perspectives to counteract tumor-induced immunosuppression.Overall, receptor engineering has led to significant advances in NK cell-based cancer immunotherapies. As technical challenges are addressed, these innovative treatments will likely reshape cancer immunotherapy.

Adoptive cell therapy for solid tumors beyond CAR-T: Current challenges and emerging therapeutic advances

Adoptive cellular immunotherapy using immune cells expressing chimeric antigen receptors (CARs) is a highly specific anti-tumor immunotherapy that has shown promise in the treatment of hematological malignancies. However, there has been a slow progress toward the treatment of solid tumors owing to the complex tumor microenvironment that affects the localization and killing ability of the CAR cells. Solid tumors with a strong immunosuppressive microenvironment and complex vascular system are unaffected by CAR cell infiltration and attack. To improve their efficacy toward solid tumors, CAR cells have been modified and upgraded by "decorating" and "pruning". This review focuses on the structure and function of CARs, the immune cells that can be engineered by CARs and the transformation strategies to overcome solid tumors, with a view to broadening ideas for the better application of CAR cell therapy for the treatment of solid tumors.

The Role of Natural Killer Cells in the Tumor Immune Microenvironment of EBV-Associated Nasopharyngeal Carcinoma

Endemic nasopharyngeal carcinoma (NPC) is closely associated with the Epstein-Barr virus (EBV), which contributes to tumor development and influences the tumor immune microenvironment (TIME) in NPC. Natural killer (NK) cells, as part of the innate immune system, play a crucial role in responding to viral infections and malignant cell transformations. Notably, NK cells possess a unique ability to target tumor cells independent of major histocompatibility complex class I (MHC I) expression. This means that MHC I-deficient tumor cells, which can escape from effective T cell attack, are susceptible to NK-cell-mediated killing. The activation of NK cells is determined by the signals generated through inhibitory and activating receptors expressed on their surface. Understanding the role of NK cells in the complex TIME of EBV+ NPC is of utmost importance. In this review, we provide a comprehensive summary of the current understanding of NK cells in NPC, focusing on their subpopulations, interactions, and cytotoxicity within the TIME. Moreover, we discuss the potential translational therapeutic applications of NK cells in NPC. This review aims to enhance our knowledge of the role of NK cells in NPC and provide valuable insights for future investigations.

Targeting natural killer cells: from basic biology to clinical application in hematologic malignancies

Natural killer (NK) cell belongs to innate lymphoid cell family that contributes to host immunosurveillance and defense without pre-immunization. Emerging studies have sought to understand the underlying mechanism behind NK cell dysfunction in tumor environments, and provide numerous novel therapeutic targets for tumor treatment. Strategies to enhance functional activities of NK cell have exhibited promising efficacy and favorable tolerance in clinical treatment of tumor patients, such as immune checkpoint blockade (ICB), chimeric antigen receptor NK (CAR-NK) cell, and bi/trispecific killer cell engager (BiKE/TriKE). Immunotherapy targeting NK cell provides remarkable advantages compared to T cell therapy, including a decreased rate of graft versus-host disease (GvHD) and neurotoxicity. Nevertheless, advanced details on how to support the maintenance and function of NK cell to obtain better response rate and longer duration still remain to be elucidated. This review systematically summarizes the profound role of NK cells in tumor development, highlights up-to-date advances and current challenges of therapy targeting NK cell in the clinical treatment of hematologic malignancies.

Breakthrough of solid tumor treatment: CAR-NK immunotherapy

As the latest and most anticipated method of tumor immunotherapy, CAR-NK therapy has received increasing attention in recent years, and its safety and high efficiency have irreplaceable advantages over CAR-T. Current research focuses on the application of CAR-NK in hematological tumors, while there are fewer studies on solid tumor. This article reviews the process of constructing CAR-NK, the effects of hypoxia and metabolic factors, NK cell surface receptors, cytokines, and exosomes on the efficacy of CAR-NK in solid tumor, and the role of CAR-NK in various solid tumor. The mechanism of action and the research status of the potential of CAR-NK in the treatment of solid tumor in clinical practice, and put forward the advantages, limitations and future problems of CAR-NK in the treatment of solid tumor.

Cellular Strategies for Separating GvHD from GvL in Haploidentical Transplantation

GvHD still remains, despite the continuous improvement of transplantation platforms, a fearful complication of transplantation from allogeneic donors. Being able to separate GvHD from GvL represents the greatest challenge in the allogeneic transplant setting. This may be possible through continuous improvement of cell therapy techniques. In this review, current cell therapies are taken into consideration, which are based on the use of TCR alpha/beta depletion, CD45RA depletion, T regulatory cell enrichment, NK-cell-based immunotherapies, and suicide gene therapies in order to prevent GvHD and maximally amplify the GvL effect in the setting of haploidentical transplantation.

Cytokine-Induced Memory-Like NK Cells: Emerging strategy for AML immunotherapy

Acute myeloid leukemia (AML) is a heterogeneous disease developed from the malignant expansion of myeloid precursor cells in the bone marrow and peripheral blood. The implementation of intensive chemotherapy and hematopoietic stem cell transplantation (HSCT) has improved outcomes associated with AML, but relapse, along with suboptimal outcomes, is still a common scenario. In the past few years, exploring new therapeutic strategies to optimize treatment outcomes has occurred rapidly. In this regard, natural killer (NK) cell-based immunotherapy has attracted clinical interest due to its critical role in immunosurveillance and their capabilities to target AML blasts. NK cells are cytotoxic innate lymphoid cells that mediate anti-viral and anti-tumor responses by producing pro-inflammatory cytokines and directly inducing cytotoxicity. Although NK cells are well known as short-lived innate immune cells with non-specific responses that have limited their clinical applications, the discovery of cytokine-induced memory-like (CIML) NK cells could overcome these challenges. NK cells pre-activated with the cytokine combination IL-12/15/18 achieved a long-term life span with adaptive immunity characteristics, termed CIML-NK cells. Previous studies documented that using CIML-NK cells in cancer treatment is safe and results in promising outcomes. This review highlights the current application, challenges, and opportunities of CIML-NK cell-based therapy in AML.

Relapse of acute myeloid leukemia after allogeneic stem cell transplantation: immune escape mechanisms and current implications for therapy

Acute myeloid leukemia (AML) is a heterogeneous disease characterized by the expansion of immature myeloid cells in the bone marrow (BM) and peripheral blood (PB) resulting in failure of normal hematopoiesis and life-threating cytopenia. Allogeneic hematopoietic stem cell transplantation (allo-HCT) is an established therapy with curative potential. Nevertheless, post-transplant relapse is common and associated with poor prognosis, representing the major cause of death after allo-HCT. The occurrence of relapse after initially successful allo-HCT indicates that the donor immune system is first able to control the leukemia, which at a later stage develops evasion strategies to escape from immune surveillance. In this review we first provide a comprehensive overview of current knowledge regarding immune escape in AML after allo-HCT, including dysregulated HLA, alterations in immune checkpoints and changes leading to an immunosuppressive tumor microenvironment. In the second part, we draw the line from bench to bedside and elucidate to what extend immune escape mechanisms of relapsed AML are yet exploited in treatment strategies. Finally, we give an outlook how new emerging technologies could help to improve the therapy for these patients, and elucidate potential new treatment options.

Adoptive NK Cell Therapy - a Beacon of Hope in Multiple Myeloma Treatment

Major advances in the treatment of multiple myeloma (MM) have been achieved by effective new agents such as proteasome inhibitors, immunomodulatory drugs, or monoclonal antibodies. Despite significant progress, MM remains still incurable and, recently, cellular immunotherapy has emerged as a promising treatment for relapsed/refractory MM. The emergence of chimeric antigen receptor (CAR) technology has transformed immunotherapy by enhancing the antitumor functions of T cells and natural killer (NK) cells, leading to effective control of hematologic malignancies. Recent advancements in gene delivery to NK cells have paved the way for the clinical application of CAR-NK cell therapy. CAR-NK cell therapy strategies have demonstrated safety, tolerability, and substantial efficacy in treating B cell malignancies in various clinical settings. However, their effectiveness in eliminating MM remains to be established. This review explores multiple approaches to enhance NK cell cytotoxicity, persistence, expansion, and manufacturing processes, and highlights the challenges and opportunities associated with CAR-NK cell therapy against MM. By shedding light on these aspects, this review aims to provide valuable insights into the potential of CAR-NK cell therapy as a promising approach for improving the treatment outcomes of MM patients.

Memory-like Differentiation, Tumor-Targeting mAbs, and Chimeric Antigen Receptors Enhance Natural Killer Cell Responses to Head and Neck Cancer

PURPOSE

Head and neck squamous cell carcinoma (HNSCC) is an aggressive tumor with low response rates to frontline PD-1 blockade. Natural killer (NK) cells are a promising cellular therapy for T cell therapy-refractory cancers, but are frequently dysfunctional in patients with HNSCC. Strategies are needed to enhance NK cell responses against HNSCC. We hypothesized that memory-like (ML) NK cell differentiation, tumor targeting with cetuximab, and engineering with an anti-EphA2 (Erythropoietin-producing hepatocellular receptor A2) chimeric antigen receptor (CAR) enhance NK cell responses against HNSCC.

EXPERIMENTAL DESIGN

We generated ML NK and conventional (c)NK cells from healthy donors, then evaluated their ability to produce IFNγ, TNF, degranulate, and kill HNSCC cell lines and primary HNSCC cells, alone or in combination with cetuximab, in vitro and in vivo using xenograft models. ML and cNK cells were engineered to express anti-EphA2 CAR-CD8A-41BB-CD3z, and functional responses were assessed in vitro against HNSCC cell lines and primary HNSCC tumor cells.

RESULTS

Human ML NK cells displayed enhanced IFNγ and TNF production and both short- and long-term killing of HNSCC cell lines and primary targets, compared with cNK cells. These enhanced responses were further improved by cetuximab. Compared with controls, ML NK cells expressing anti-EphA2 CAR had increased IFNγ and cytotoxicity in response to EphA2+ cell lines and primary HNSCC targets.

CONCLUSIONS

These preclinical findings demonstrate that ML differentiation alone or coupled with either cetuximab-directed targeting or EphA2 CAR engineering were effective against HNSCCs and provide the rationale for investigating these combination approaches in early phase clinical trials for patients with HNSCC.

Good manufacturing practice production of CD34+ progenitor-derived NK cells for adoptive immunotherapy in acute myeloid leukemia

Allogeneic natural killer (NK) cell-based immunotherapy is a promising, well-tolerated adjuvant therapeutic approach for acute myeloid leukemia (AML). For reproducible NK cell immunotherapy, a homogenous, pure and scalable NK cell product is preferred. Therefore, we developed a good manufacturing practice (GMP)-compliant, cytokine-based ex vivo manufacturing process for generating NK cells from CD34+ hematopoietic stem and progenitor cells (HSPC). This manufacturing process combines amongst others IL15 and IL12 and the aryl hydrocarbon receptor antagonist StemRegenin-1 (SR1) to generate a consistent and active NK cell product that fits the requirements for NK cell immunotherapy well. The cell culture protocol was first optimized to generate NK cells with required expansion and differentiation capacity in GMP-compliant closed system cell culture bags. In addition, phenotype, antitumor potency, proliferative and metabolic capacity were evaluated to characterize the HSPC-NK product. Subsequently, seven batches were manufactured for qualification of the process. All seven runs demonstrated consistent results for proliferation, differentiation and antitumor potency, and preliminary specifications for the investigational medicinal product for early clinical phase trials were set. This GMP-compliant manufacturing process for HSPC-NK cells (named RNK001 cells) is used to produce NK cell batches applied in the clinical trial 'Infusion of ex vivo-generated allogeneic natural killer cells in combination with subcutaneous IL2 in patients with acute myeloid leukemia' approved by the Dutch Ethics Committee (EudraCT 2019-001929-27).

Driving natural killer cell-based cancer immunotherapy for cancer treatment: An arduous journey to promising ground

Immunotherapy represents one of the most effective strategies for cancer treatment. Recently, progress has been made in using natural killer (NK) cells for cancer therapy. NK cells can directly kill tumor cells without pre-sensitization and thus show promise in clinical applications, distinct from the use of T cells. Whereas, research and development on NK cell-based immunotherapy is still in its infancy, and enhancing the therapeutic effects of NK cells remains a key problem to be solved. An incompletely understanding of the mechanisms of action of NK cells, immune resistance in the tumor microenvironment, and obstacles associated with the delivery of therapeutic agents in vivo, represent three mountains that need to be scaled. Here, we firstly describe the mechanisms underlying the development, activity, and maturation of NK cells, and the formation of NK‑cell immunological synapses. Secondly, we discuss strategies for NK cell-based immunotherapy strategies, including adoptive transfer of NK cell therapy and treatment with cytokines, monoclonal antibodies, and immune checkpoint inhibitors targeting NK cells. Finally, we review the use of nanotechnology to overcome immune resistance, including enhancing the anti-tumor efficiency of chimeric antigen receptor-NK, cytokines and immunosuppressive-pathways inhibitors, promoting NK cell homing and developing NK cell-based nano-engagers.

Co-Expression of an IL-15 Superagonist Facilitates Self-Enrichment of GD2-Targeted CAR-NK Cells and Mediates Potent Cell Killing in the Absence of IL-2

In contrast to T lymphocytes, natural killer (NK) cells do not require prior sensitization but are rapidly activated upon encountering virally infected or neoplastic cells. In addition, NK cells can be safely applied in an allogeneic setting, making them important effector cells for the development of off-the-shelf therapeutics for adoptive cancer immunotherapy. To further enhance their therapeutic potential, here, we engineered continuously expanding NK-92 cells as a clinically relevant model to express a humanized second-generation chimeric antigen receptor (CAR) with a composite CD28-CD3ζ signaling domain (hu14.18.28.z) that targets the disialoganglioside GD2, which is expressed at high levels by neuroblastoma cells and other tumors of neuroectodermal origin. In a separate approach, we fused an IL-15 superagonist (RD-IL15) to the GD2-CAR via a P2A processing site. Lentivirally transduced NK-92/hu14.18.28.z and NK-92/hu14.18.28.z_RD-IL15 cells both displayed high and stable CAR surface expression and specific cytotoxicity toward GD2-positive tumor cells. GD2-CAR NK cells carrying the RD-IL15 construct in addition expressed the IL-15 superagonist, resulting in self-enrichment and targeted cell killing in the absence of exogenous IL-2. Furthermore, co-culture with RD-IL15-secreting GD2-CAR NK cells markedly enhanced proliferation and cytotoxicity of bystander immune cells in a paracrine manner. Our results demonstrate that GD2-CAR NK cells co-expressing the IL-15 superagonist mediate potent direct and indirect antitumor effects, suggesting this strategy as a promising approach for the further development of functionally enhanced cellular therapeutics.

Polymer Micropatches as Natural Killer Cell Engagers for Tumor Therapy

Natural killer (NK) cell therapies have emerged as a potential therapeutic approach to various cancers. Their efficacy, however, is limited by their low persistence and anergy. Current approaches to sustain NK cell persistence in vivo include genetic modification, activation via pretreatment, or coadministration of supporting cytokines or antibodies. Such supporting therapies exhibit limited efficacy in vivo, in part due to the reversal of their effect within the immunosuppressive tumor microenvironment and off-target toxicity. Here, we report a material-based approach to address this challenge. Specifically, we describe the use of polymeric micropatches as a platform for sustained, targeted activation of NK cells, an approach referred to as microparticles as cell engagers (MACE). Poly(lactide-co-glycolic) acid (PLGA) micropatches, 4-8 μm in diameter and surface-modified with NK cell receptor targeting antibodies, exhibited strong adhesion to NK cells and induced their activation without the need of coadministered cytokines. The activation induced by MACE was greater than that induced by nanoparticles, attesting to the crucial role of MACE geometry in the activation of NK cells. MACE-bound NK cells remained viable and exhibited trans-endothelial migration and antitumor activity in vitro. MACE-bound NK cells activated T cells, macrophages, and dendritic cells in vitro. Adoptive transfer of NK-MACE also demonstrated superior antitumor efficacy in a mouse melanoma lung metastasis model compared to unmodified NK cells. Overall, MACE offers a simple, scalable, and effective way of activating NK cells and represents an attractive platform to improve the efficacy of NK cell therapy.

Understanding NK cell biology for harnessing NK cell therapies: targeting cancer and beyond

Gene-engineered immune cell therapies have partially transformed cancer treatment, as exemplified by the use of chimeric antigen receptor (CAR)-T cells in certain hematologic malignancies. However, there are several limitations that need to be addressed to target more cancer types. Natural killer (NK) cells are a type of innate immune cells that represent a unique biology in cancer immune surveillance. In particular, NK cells obtained from heathy donors can serve as a source for genetically engineered immune cell therapies. Therefore, NK-based therapies, including NK cells, CAR-NK cells, and antibodies that induce antibody-dependent cellular cytotoxicity of NK cells, have emerged. With recent advances in genetic engineering and cell biology techniques, NK cell-based therapies have become promising approaches for a wide range of cancers, viral infections, and senescence. This review provides a brief overview of NK cell characteristics and summarizes diseases that could benefit from NK-based therapies. In addition, we discuss recent preclinical and clinical investigations on the use of adoptive NK cell transfer and agents that can modulate NK cell activity.

Advances in engineering and delivery strategies for cytokine immunotherapy

INTRODUCTION

Cytokine immunotherapy is a growing field for the treatment of cancer, infectious disease, autoimmunity, and other ailments. Therapeutic cytokines are a class of secreted, small proteins that play a pivotal role in regulating the innate and adaptive immune system by provoking or mitigating immune responses. In the clinic, cytokines are frequently combined with other treatments, such as small molecules and monoclonal antibodies. However, the clinical translation of cytokine therapies is hindered by their short half-life, pleiotropic nature, and off-target effects, which cause diminished efficacy and severe systemic toxicity. Such toxicity limits dosage, thus resulting in suboptimal doses. Accordingly, numerous efforts have been devoted to exploring strategies to promote cytokine therapies by improving their tissue specificity and pharmacokinetics.

AREAS COVERED

Preclinical and clinical research into bioengineering and delivery strategies for cytokines, consisting of bioconjugation, fusion proteins, nanoparticles, and scaffold-based systems.

EXPERT OPINION

These approaches pave the way for the development of next-generation cytokine treatments with greater clinical benefit and reduced toxicity, circumventing such issues currently associated with cytokine therapy.

Allogeneic natural killer cell therapy

Interest in adoptive cell therapy for treating cancer is exploding owing to early clinical successes of autologous chimeric antigen receptor (CAR) T lymphocyte therapy. However, limitations using T cells and autologous cell products are apparent as they (1) take weeks to generate, (2) utilize a 1:1 donor-to-patient model, (3) are expensive, and (4) are prone to heterogeneity and manufacturing failures. CAR T cells are also associated with significant toxicities, including cytokine release syndrome, immune effector cell-associated neurotoxicity syndrome, and prolonged cytopenias. To overcome these issues, natural killer (NK) cells are being explored as an alternative cell source for allogeneic cell therapies. NK cells have an inherent ability to recognize cancers, mediate immune functions of killing and communication, and do not induce graft-versus-host disease, cytokine release syndrome, or immune effector cell-associated neurotoxicity syndrome. NK cells can be obtained from blood or cord blood or be derived from hematopoietic stem and progenitor cells or induced pluripotent stem cells, and can be expanded and cryopreserved for off-the-shelf availability. The first wave of point-of-care NK cell therapies led to the current allogeneic NK cell products being investigated in clinical trials with promising preliminary results. Basic advances in NK cell biology and cellular engineering have led to new translational strategies to block inhibition, enhance and broaden target cell recognition, optimize functional persistence, and provide stealth from patients' immunity. This review details NK cell biology, as well as NK cell product manufacturing, engineering, and combination therapies explored in the clinic leading to the next generation of potent, off-the-shelf cellular therapies for blood cancers.

Human natural killer cells: Form, function, and development

Human natural killer (NK) cells are innate lymphoid cells that mediate important effector functions in the control of viral infection and malignancy. Their ability to distinguish "self" from "nonself" and lyse virally infected and tumorigenic cells through germline-encoded receptors makes them important players in maintaining human health and a powerful tool for immunotherapeutic applications and fighting disease. This review introduces our current understanding of NK cell biology, including key facets of NK cell differentiation and the acquisition and execution of NK cell effector function. Further, it addresses the clinical relevance of NK cells in both primary immunodeficiency and immunotherapy. It is intended to provide an up-to-date and comprehensive overview of this important and interesting innate immune effector cell subset.

The role of interleukin-15 in the development and treatment of hematological malignancies

Cytokines are a vital component of the immune system that controls the activation and growth of blood cells. However, chronic overexpression of cytokines can trigger cellular events leading to malignant transformation. The cytokine interleukin-15 (IL-15) is of particular interest, which has been shown to contribute to the development and progression of various hematological malignancies. This review will provide an overview of the impact of the immunopathogenic function of IL-15 by studying its role in cell survival, proliferation, inflammation, and treatment resistance. We will also review therapeutic approaches for inhibiting IL-15 in blood cancers.

Adoptive Cell Therapy for T-Cell Malignancies

T-cell malignancies are often aggressive and associated with poor prognoses. Adoptive cell therapy has recently shown promise as a new line of therapy for patients with hematological malignancies. However, there are currently challenges in applying adoptive cell therapy to T-cell malignancies. Various approaches have been examined in preclinical and clinical studies to overcome these obstacles. This review aims to provide an overview of the recent progress on adoptive cell therapy for T-cell malignancies. The benefits and drawbacks of different types of adoptive cell therapy are discussed. The potential advantages and current applications of innate immune cell-based adoptive cell therapy for T cell malignancies are emphasized.

Immune cell interactions in tuberculosis

Despite having been identified as the organism that causes tuberculosis in 1882, Mycobacterium tuberculosis has managed to still evade our understanding of the protective immune response against it, defying the development of an effective vaccine. Technology and novel experimental models have revealed much new knowledge, particularly with respect to the heterogeneity of the bacillus and the host response. This review focuses on certain immunological elements that have recently yielded exciting data and highlights the importance of taking a holistic approach to understanding the interaction of M. tuberculosis with the many host cells that contribute to the development of protective immunity.

Quadruple gene-engineered natural killer cells enable multi-antigen targeting for durable antitumor activity against multiple myeloma

Allogeneic natural killer (NK) cell adoptive transfer is a promising treatment for several cancers but is less effective for the treatment of multiple myeloma. In this study, we report on quadruple gene-engineered induced pluripotent stem cell (iPSC)-derived NK cells designed for mass production from a renewable source and for dual targeting against multiple myeloma through the introduction of an NK cell-optimized chimeric antigen receptor (CAR) specific for B cell maturation antigen (BCMA) and a high affinity, non-cleavable CD16 to augment antibody-dependent cellular cytotoxicity when combined with therapeutic anti-CD38 antibodies. Additionally, these cells express a membrane-bound interleukin-15 fusion molecule to enhance function and persistence along with knock out of CD38 to prevent antibody-mediated fratricide and enhance NK cell metabolic fitness. In various preclinical models, including xenogeneic adoptive transfer models, quadruple gene-engineered NK cells consistently demonstrate durable antitumor activity independent of exogenous cytokine support. Results presented here support clinical translation of this off-the-shelf strategy for effective treatment of multiple myeloma.

Natural killer cells in clinical development as non-engineered, engineered, and combination therapies

Natural killer (NK) cells are unique immune effectors able to kill cancer cells by direct recognition of surface ligands, without prior sensitization. Allogeneic NK transfer is a highly valuable treatment option for cancer and has recently emerged with hundreds of clinical trials paving the way to finally achieve market authorization. Advantages of NK cell therapies include the use of allogenic cell sources, off-the-shelf availability, and no risk of graft-versus-host disease (GvHD). Allogeneic NK cell therapies have reached the clinical stage as ex vivo expanded and differentiated non-engineered cells, as chimeric antigen receptor (CAR)-engineered or CD16-engineered products, or as combination therapies with antibodies, priming agents, and other drugs. This review summarizes the recent clinical status of allogeneic NK cell-based therapies for the treatment of hematological and solid tumors, discussing the main characteristics of the different cell sources used for NK product development, their use in cell manufacturing processes, the engineering methods and strategies adopted for genetically modified products, and the chosen approaches for combination therapies. A comparative analysis between NK-based non-engineered, engineered, and combination therapies is presented, examining the choices made by product developers regarding the NK cell source and the targeted tumor indications, for both solid and hematological cancers. Clinical trial outcomes are discussed and, when available, assessed in comparison with preclinical data. Regulatory challenges for product approval are reviewed, highlighting the lack of specificity of requirements and standardization between products. Additionally, the competitive landscape and business field is presented. This review offers a comprehensive overview of the effort driven by biotech and pharmaceutical companies and by academic centers to bring NK cell therapies to pivotal clinical trial stages and to market authorization.

Next Generation Immuno-Oncology Strategies: Unleashing NK Cells Activity

In recent years, immunotherapy has become a powerful therapeutic option against multiple malignancies. The unique capacity of natural killer (NK) cells to attack cancer cells without antigen specificity makes them an optimal immunotherapeutic tool for targeting tumors. Several approaches are currently being pursued to maximize the anti-tumor properties of NK cells in the clinic, including the development of NK cell expansion protocols for adoptive transfer, the establishment of a favorable microenvironment for NK cell activity, the redirection of NK cell activity against tumor cells, and the blockage of inhibitory mechanisms that constrain NK cell function. We here summarize the recent strategies in NK cell-based immunotherapies and discuss the requirement to further optimize these approaches for enhancement of the clinical outcome of NK cell-based immunotherapy targeting tumors.

Harnessing IL-15 signaling to potentiate NK cell-mediated cancer immunotherapy

Natural killer (NK) cells, a crucial component of the innate immune system, have long been of clinical interest for their antitumor properties. Almost every aspect of NK cell immunity is regulated by interleukin-15 (IL-15), a cytokine in the common γ-chain family. Several current clinical trials are using IL-15 or its analogs to treat various cancers. Moreover, NK cells are being genetically modified to produce membrane-bound or secretory IL-15. Here, we discuss the key role of IL-15 signaling in NK cell immunity and provide an up-to-date overview of IL-15 in NK cell therapy.

The soldiers needed to be awakened: Tumor-infiltrating immune cells

In the tumor microenvironment, tumor-infiltrating immune cells (TIICs) are a key component. Different types of TIICs play distinct roles. CD8+ T cells and natural killer (NK) cells could secrete soluble factors to hinder tumor cell growth, whereas regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) release inhibitory factors to promote tumor growth and progression. In the meantime, a growing body of evidence illustrates that the balance between pro- and anti-tumor responses of TIICs is associated with the prognosis in the tumor microenvironment. Therefore, in order to boost anti-tumor response and improve the clinical outcome of tumor patients, a variety of anti-tumor strategies for targeting TIICs based on their respective functions have been developed and obtained good treatment benefits, including mainly immune checkpoint blockade (ICB), adoptive cell therapies (ACT), chimeric antigen receptor (CAR) T cells, and various monoclonal antibodies. In recent years, the tumor-specific features of immune cells are further investigated by various methods, such as using single-cell RNA sequencing (scRNA-seq), and the results indicate that these cells have diverse phenotypes in different types of tumors and emerge inconsistent therapeutic responses. Hence, we concluded the recent advances in tumor-infiltrating immune cells, including functions, prognostic values, and various immunotherapy strategies for each immune cell in different tumors.

Strategies for Potentiating NK-Mediated Neuroblastoma Surveillance in Autologous or HLA-Haploidentical Hematopoietic Stem Cell Transplants

Simple Summary

High-risk neuroblastomas (HR-NB) are malignant tumors of childhood that are treated with a very aggressive and life-threatening approach; this includes autologous hemopoietic stem cell transplantation (HSCT) and the infusion of a mAb targeting the GD2 tumor-associated antigen. Although the current treatment provided benefits, the 5-year overall survival remains below 50% due to relapses and refractoriness to therapy. Thus, there is an urgent need to ameliorate the standard therapeutic protocol, particularly improving the immune-mediated anti-tumor responses. Our review aims at summarizing and critically discussing novel immunotherapeutic strategies in HR-NB, including NK cell-based therapies and HLA-haploidentical HSCT from patients’ family.

Abstract

High-risk neuroblastomas (HR-NB) still have an unacceptable 5-year overall survival despite the aggressive therapy. This includes standardized immunotherapy combining autologous hemopoietic stem cell transplantation (HSCT) and the anti-GD2 mAb. The treatment did not significantly change for more than one decade, apart from the abandonment of IL-2, which demonstrated unacceptable toxicity. Of note, immunotherapy is a promising therapeutic option in cancer and could be optimized by several strategies. These include the HLA-haploidentical αβT/B-depleted HSCT, and the antibody targeting of novel NB-associated antigens such as B7-H3, and PD1. Other approaches could limit the immunoregulatory role of tumor-derived exosomes and potentiate the low antibody-dependent cell cytotoxicity of CD16 dim/neg NK cells, abundant in the early phase post-transplant. The latter effect could be obtained using multi-specific tools engaging activating NK receptors and tumor antigens, and possibly holding immunostimulatory cytokines in their construct. Finally, treatments also consider the infusion of novel engineered cytokines with scarce side effects, and cell effectors engineered with chimeric antigen receptors (CARs). Our review aims to discuss several promising strategies that could be successfully exploited to potentiate the NK-mediated surveillance of neuroblastoma, particularly in the HSCT setting. Many of these approaches are safe, feasible, and effective at pre-clinical and clinical levels.

Underlying mechanisms of evasion from NK cells as rational for improvement of NK cell-based immunotherapies

Natural killer (NK) cells belong to the family of innate immune cells with the capacity to recognize and kill tumor cells. Different phenotypes and functional properties of NK cells have been described in tumor patients, which could be shaped by the tumor microenvironment. The discovery of HLA class I-specific inhibitory receptors controlling NK cell activity paved the way to the fundamental concept of modulating immune responses that are regulated by an array of inhibitory receptors, and emphasized the importance to explore the potential of NK cells in cancer therapy. Although a whole range of NK cell-based approaches are currently being developed, there are still major challenges that need to be overcome for improved efficacy of these therapies. These include escape of tumor cells from NK cell recognition due to their expression of inhibitory molecules, immune suppressive signals of NK cells, reduced NK cell infiltration of tumors, an immune suppressive micromilieu and limited in vivo persistence of NK cells. Therefore, this review provides an overview about the NK cell biology, alterations of NK cell activities, changes in tumor cells and the tumor microenvironment contributing to immune escape or immune surveillance by NK cells and their underlying molecular mechanisms as well as the current status and novel aspects of NK cell-based therapeutic strategies including their genetic engineering and their combination with conventional treatment options to overcome tumor-mediated evasion strategies and improve therapy efficacy.

Overcoming tumor resistance mechanisms in CAR-NK cell therapy

Despite the impressive results of autologous CAR-T cell therapy in refractory B lymphoproliferative diseases, CAR-NK immunotherapy emerges as a safer, faster, and cost-effective approach with no signs of severe toxicities as described for CAR-T cells. Permanently scrutinized for its efficacy, recent promising data in CAR-NK clinical trials point out the achievement of deep, high-quality responses, thus confirming its potential clinical use. Although CAR-NK cell therapy is not significantly affected by the loss or downregulation of its CAR tumor target, as in the case of CAR-T cell, a plethora of common additional tumor intrinsic or extrinsic mechanisms that could also disable NK cell function have been described. Therefore, considering lessons learned from CAR-T cell therapy, the emergence of CAR-NK cell therapy resistance can also be envisioned. In this review we highlight the processes that could be involved in its development, focusing on cytokine addiction and potential fratricide during manufacturing, poor tumor trafficking, exhaustion within the tumor microenvironment (TME), and NK cell short in vivo persistence on account of the limited expansion, replicative senescence, and rejection by patient’s immune system after lymphodepletion recovery. Finally, we outline new actively explored alternatives to overcome these resistance mechanisms, with a special emphasis on CRISPR/Cas9 mediated genetic engineering approaches, a promising platform to optimize CAR-NK cell function to eradicate refractory cancers.

NK Cell-Based Immunotherapy in Colorectal Cancer

Human Natural Killer (NK) cells are all round players in immunity thanks to their powerful and immediate response against transformed cells and the ability to modulate the subsequent adaptive immune response. The potential of immunotherapies based on NK cell involvement has been initially revealed in the hematological setting but has inspired the design of different immune tools to also be applied against solid tumors, including colorectal cancer (CRC). Indeed, despite cancer prevention screening plans, surgery, and chemotherapy strategies, CRC is one of the most widespread cancers and with the highest mortality rate. Therefore, further efficient and complementary immune-based therapies are in urgent need. In this review, we gathered the most recent advances in NK cell-based immunotherapies aimed at fighting CRC, in particular, the use of monoclonal antibodies targeting tumor-associated antigens (TAAs), immune checkpoint blockade, and adoptive NK cell therapy, including NK cells modified with chimeric antigen receptor (CAR-NK).

Next Generation Natural Killer Cells for Cancer Immunotherapy

In recent years, immunotherapy for cancer has become mainstream with several products now authorized for therapeutic use in the clinic and are becoming the standard of care for some malignancies. Chimeric antigen receptor (CAR)-T cell therapies have demonstrated substantial efficacy for the treatment of hematological malignancies; however, they are complex and currently expensive to manufacture, and they can generate life-threatening adverse events such as cytokine release syndrome (CRS). The limitations of current CAR-T cells therapies have spurred an interest in alternative immunotherapy approaches with safer risk profiles and with less restrictive manufacturing constraints. Natural killer (NK) cells are a population of immune effector cells with potent anti-viral and anti-tumor activity; they have the capacity to swiftly recognize and kill cancer cells without the need of prior stimulation. Although NK cells are naturally equipped with cytotoxic potential, a growing body of evidence shows the added benefit of engineering them to better target tumor cells, persist longer in the host, and be fitter to resist the hostile tumor microenvironment (TME). NK-cell-based immunotherapies allow for the development of allogeneic off-the-shelf products, which have the potential to be less expensive and readily available for patients in need. In this review, we will focus on the advances in the development of engineering of NK cells for cancer immunotherapy. We will discuss the sourcing of NK cells, the technologies available to engineer NK cells, current clinical trials utilizing engineered NK cells, advances on the engineering of receptors adapted for NK cells, and stealth approaches to avoid recipient immune responses. We will conclude with comments regarding the next generation of NK cell products, i.e., armored NK cells with enhanced functionality, fitness, tumor-infiltration potential, and with the ability to overcome tumor heterogeneity and immune evasion.

From CD16a Biology to Antibody-Dependent Cell-Mediated Cytotoxicity Improvement

Antibody-dependent cell-mediated cytotoxicity (ADCC) is a potent cytotoxic mechanism that is mainly mediated in humans by natural killer (NK) cells. ADCC mediates the clinical benefit of several widely used cytolytic monoclonal antibodies (mAbs), and increasing its efficacy would improve cancer immunotherapy. CD16a is a receptor for the Fc portion of IgGs and is responsible to trigger NK cell-mediated ADCC. The knowledge of the mechanism of action of CD16a gave rise to several strategies to improve ADCC, by working on either the mAbs or the NK cell. In this review, we give an overview of CD16a biology and describe the latest strategies employed to improve antibody-dependent NK cell cytotoxicity.

2022 update on the scientific premise and clinical trials for IL-15 agonists as cancer immunotherapy

Diverse cytokines and their receptors on immune cells constitute a highly complex network in the immune system. Some therapeutic cytokines and their derivatives have been approved for cancer treatment. IL-15 is an immune-regulating cytokine with multiple functions, among which the function of activating the immunity of cancer patients has great potential in cancer immunotherapy. In this review, we introduce the functions of IL-15 and discuss its role in regulating the immune system in different immune cells. Meanwhile, we will address the applications of IL-15 agonists in cancer immunotherapy and provide prospects for the next generation of therapeutic designs. Although many challenges remain, IL-15 agonists offer a new therapeutic option in the future direction of cancer immunotherapy.