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Objective: Small cell lung cancer (SCLC) is commonly recognized as the most fatal lung cancer type. Despite substantial advances in immune checkpoint blockade therapies for treating solid cancers, their benefits are limited to a minority of patients with SCLC. In the present study, novel indicators for predicting the outcomes and molecular targets for SCLC treatment were elucidated. Methods: We conducted bioinformatics analysis to identify the key genes associated with tumor-infiltrating lymphocytes in SCLC. The functional role of the key gene identified in SCLC was determined both in vitro and in vivo. Results: A significant correlation was observed between patient survival and CD56dim natural killer (NK) cell proportion. Furthermore, we noted that the hub gene ubiquitin-specific protease 1 (USP1) is closely correlated with both CD56dim NK cells and overall survival in SCLC. Bioinformatics analysis revealed that USP1 is upregulated in SCLC. In addition, gene set enrichment analysis revealed that USP1 overexpression hinders NK cell-mediated immune responses. By co-cultivating NK-92 cells with SCLC cells, we demonstrated that NK cell cytotoxicity against SCLC could be improved either via USP1 knock-down or pharmacological inhibition. Furthermore, using a nude-mice xenograft tumor model, we noted that USP1 inhibition effectively suppressed tumor proliferation and increased the expression of NK cell-associated markers. Conclusions: Our study findings highlight the importance of NK cells in regulating SCLC. USP1 overexpression can inhibit NK cell-mediated immunity; therefore, USP1 may serve not only as a prognostic biomarker but also as a potential molecular target of SCLC therapy. [ABSTRACT FROM AUTHOR]

BackgroundMethodsResultsConclusionHead and neck squamous cell carcinoma (HNSCC) has a poor prognosis, and current treatments are limited by high toxicity and low survival rates, highlighting the need for new therapeutic approaches. Natural killer (NK) cells can identify and eliminate cancer cells without prior antigen exposure. Radiotherapy directly targets tumors and increases activating ligands on tumor cells, promoting NK cell interactions. Cetuximab, an EGFR-targeting antibody, enhances NK cell cytotoxicity. Additionally, anti-PD-1 antibodies may further boost NK cell function by blocking inhibitory signals. The study aimed to enhance HNSCC treatment efficacy by combining radiotherapy and targeted therapy with expanded NK cells.NK cells were isolated, activated, and expanded from healthy donors. The FaDu and SCC-47 cell lines were inoculated into NOD/SCID mice. The mice were treated with PD-1 inhibitors, cetuximab, and radiation, followed by intravenous injection of NK cells.Radiation increased ligands that regulate NK cell sensitivity. The combination of cetuximab, radiotherapy, and expanded NK cells significantly suppressed cancer progression and improved survival rates. However, adding anti-PD-1 antibodies did not further enhance outcomes.This study suggests that a multimodal approach combining cetuximab, radiotherapy, and NK cells can significantly improve HNSCC therapy efficacy, offering a novel and promising treatment strategy. [ABSTRACT FROM AUTHOR]

Background: Natural killer (NK) cells play crucial roles in mediating anti-cancer activity in breast cancer (BRCA). However, the potential of NK cell-related molecules in predicting BRCA outcomes and guiding personalized therapy remains largely unexplored. This study focused on developing a prognostic and therapeutic prediction model for BRCA by incorporating NK cell-related genes. Methods: The data analyzed primarily originated from the TCGA and GEO databases. The prognostic role of NK cells was evaluated, and marker genes of NK cells were identified via single-cell analysis. Module genes closely associated with immunotherapy resistance were identified by bulk transcriptome-based weighted correlation network analysis (WGCNA). Following taking intersection and LASSO regression, NK-related genes (NKRGs) relevant to BRCA prognosis were screened, and the NK-related prognostic signature was subsequently constructed. Analyses were further expanded to clinicopathological relevance, GSEA, tumor microenvironment (TME) analysis, immune function, immunotherapy responsiveness, and chemotherapeutics. Key NKRGs were screened by machine learning and validated by spatial transcriptomics (ST) and immunohistochemistry (IHC). Results: Tumor-infiltrating NK cells are a favorable prognostic factor in BRCA. By combining scRNA-seq and bulk transcriptomic analyses, we identified 7 NK-related prognostic NKRGs (CCL5, EFHD2, KLRB1, C1S, SOCS3, IRF1, and CCND2) and developed an NK-related risk scoring (NKRS) system. The prognostic reliability of NKRS was verified through survival and clinical relevance analyses across multiple cohorts. NKRS also demonstrated robust predictive power in various aspects, including TME landscape, immune functions, immunotherapy responses, and chemotherapeutic sensitivity. Additionally, KLRB1 and CCND2 emerged as key prognostic NKRGs identified through machine learning and external validation, with their expression correlation with NK cells confirmed in BRCA specimens by ST and IHC. Conclusions: We developed a novel NK-related gene signature that has proven valuable for evaluating prognosis and treatment response in BRCA, expecting to advance precision medicine of BRCA. [ABSTRACT FROM AUTHOR]

The formation of a lytic immunological synapse (IS) is crucial for cytotoxic lymphocytes to accurately target and effectively eliminate malignant cells. While significant attention has been focused on the lymphocyte side of the IS, particularly its role as a secretory domain for lytic granules, the cancer cell side of the IS has remained relatively underexplored. Recent findings have revealed that cancer cells can rapidly polarize their actin cytoskeleton toward the IS upon interaction with natural killer (NK) cells, thereby evading NK cell-mediated cytotoxicity. In this Brief Research Report, we present preliminary findings suggesting that actin cytoskeleton remodeling at the cancer cell side of the IS is associated with the targeted secretion of small extracellular vesicles towards the interacting NK cell. We observed that multivesicular bodies (MVBs) preferentially accumulate in the synaptic region in cancer cells exhibiting synaptic accumulation of F-actin, compared to those lacking actin cytoskeleton remodeling. Extracellular immunofluorescence staining revealed increased surface exposure of CD63 at the cancer cell side of the IS, suggestive of the fusion of MVBs with the plasma membrane. This hypothesis was supported by a pH-sensitive probe demonstrating dynamic trafficking of CD63 to the extracellular region of the IS. Collectively, our data support the notion that cancer cells can engage in targeted secretion of extracellular vesicles in response to NK cell attack, underscoring the need for further research into the potential role of this process in facilitating cancer cell immune evasion. [ABSTRACT FROM AUTHOR]

Nasopharyngeal carcinoma (NPC) is a distinct malignancy of the nasopharynx and is consistently associated with the Epstein-Barr virus (EBV) infection. Its unique anatomical location and complex aetiology often result in advancedstage disease at first diagnosis. While radiotherapy (RT) and chemotherapy have been the mainstays of treatment, they often fail to prevent tumour recurrence and metastasis, leading to high rates of treatment failure and mortality. Recent advancement in cell-based therapies, such as chimeric antigen receptor (CAR)-T cell therapy, have shown great promise in hematological malignancies and are now being investigated for NPC. However, challenges such as targeting specific tumour antigens, limited T cell persistence and proliferation, and managing treatment-related toxicities must be addressed. Extensive research is needed to enhance the effectiveness and safety of these therapies, paving the way for their integration into standard clinical practice for better management of NPC and a better quality of life for human health. [ABSTRACT FROM AUTHOR]

Background: Natural killer (NK) cells are proposed to participate in coronary artery disease (CAD) development. However, little is known about how CAD patients' NK cells respond to different stimulatory factors in terms of proliferation capability. Methods and results: Twenty-nine CAD patients' peripheral blood NK cells were isolated and individually treated with IL-2, IL-12, IL-15, IL-18, IL-21, cortisone acetate, hydrocortisone, or ascorbic acid for 36 hours, followed by cell cycle analysis using flow cytometry. The ratio of S and G2/M phase cell number to total cell number was defined as a proliferation index (PrI) and used for proliferative capability indication. The results showed that these eight factors resulted in different life cycle changes in the 29 NK cell samples. Remarkably, 28 out of 29 NK cell samples showed an obvious increase in PrI upon ascorbic acid treatment. The serum lactate dehydrogenase (LDH) level of the 29 CAD patients was measured. The results showed a negative correlation between serum LDH level and the CAD patients' NK cell PrI upon stimulation of interleukins, but not the non-interleukin stimulators. Consistently, a retrospective analysis of 46 CAD patients and 32 healthy donors showed that the circulating NK cell number negatively correlated with the serum LDH level in CAD patients. Unexpectedly, addition of LDH to NK cells significantly enhanced the production of IFN-γ, IL-10 and TNF-α, suggesting a strong regulatory role on NK cell's function. Conclusion: Ascorbic acid could promote the proliferation of the CAD patients' NK cells; LDH serum level may function as an indicator for NK cell proliferation capability and an immune-regulatory factor. [ABSTRACT FROM AUTHOR]

Introduction: NK cells can mediate tumor cell killing by natural cytotoxicity and by antibody-dependent cell-mediated cytotoxicity (ADCC), an anti-tumor mechanism mediated through the IgG Fc receptor CD16A (FcgRIIIA). CD16A polymorphisms conferring increased affinity for IgG positively correlate with clinical outcomes during monoclonal antibody therapy for lymphoma, linking increased binding affinity with increased therapeutic potential via ADCC. We have previously reported on the FcgR fusion CD64/16A consisting of the extracellular region of CD64 (FcgRI), a high-affinity Fc receptor normally expressed by myeloid cells, and the transmembrane/cytoplasmic regions of CD16A, to create a highly potent and novel activating fusion receptor. Here, we evaluate the therapeutic potential of engineered induced pluripotent stem cell (iPSC)-derived NK (iNK) cells expressing CD64/16A as an "off-the-shelf", antibody-armed cellular therapy product with multi-antigen targeting potential. Methods: iNK cells were generated from iPSCs engineered to express CD64/16A and an interleukin (IL)-15/IL-15Ra fusion (IL-15RF) protein for cytokine independence. iNK cells and peripheral blood NK cells were expanded using irradiated K562-mbIL21-41BBL feeder cells to examine in in vitro and in vivo assays using the Raji lymphoma cell line. ADCC was evaluated in real-time by IncuCyte assays and using a xenograft mouse model with high circulating levels of human IgG. Results: Our data show that CD64/16A expressing iNK cells can mediate potent anti-tumor activity against human B cell lymphoma. In particular, (i) under suboptimal conditions, including low antibody concentrations and low effector-to-target ratios, iNK-CD64/16A cells mediate ADCC, (ii) iNK-CD64/16A cells can be pre-loaded with tumor-targeting antibodies (arming) to elicit ADCC, (iii) armed iNK-CD64/16A cells can be repurposed with additional antibodies to target new tumor antigens, and (iv) cryopreserved, armed iNKCD64/16A are capable of sustained ADCC in a tumor xenograft model under saturating levels of human IgG. Discussion: iNK-CD64/16A cells allow for a flexible use of antibodies (antibody arming and antibody targeting), and an "off-the-shelf" platform for multi-antigen recognition to overcome limitations of adoptive cell therapies expressing fixed antigen receptors leading to cancer relapse due to antigen escape variants. [ABSTRACT FROM AUTHOR]

Recent progress on chimeric antigen receptor (CAR)-NK cells has shown promising results in treating CD19-positive lymphoid tumors with minimal toxicities [including graft versus host disease (GvHD) and cytokine release syndrome (CRS) in clinical trials. Nevertheless, the use of CAR-NK cells in combating viral infections has not yet been fully explored. Previous studies have shown that CAR-NK cells expressing S309 single-chain fragment variable (scFv), hereinafter S309-CAR-NK cells, can bind to SARS-CoV-2 wildtype pseudotyped virus (PV) and effectively kill cells expressing wild-type spike protein in vitro. In this study, we further demonstrate that the S309-CARNK cells can bind to different SARS-CoV-2 variants, including the B.1.617.2 (Delta), B.1.621 (Mu), and B.1.1.529 (Omicron) variants in vitro. We also show that S309-CAR-NK cells reduce virus loads in the NOD/SCID gamma (NSG) mice expressing the human angiotensin-converting enzyme 2 (hACE2) receptor challenged with SARS-CoV-2 wild-type (strain USA/WA1/2020). Our study demonstrates the potential use of S309-CAR-NK cells for inhibiting infection by SARS-CoV-2 and for the potential treatment of COVID-19 patients unresponsive to otherwise currently available therapeutics. IMPORTANCE Chimeric antigen receptor (CAR)-NK cells can be “off-the-shelf” products that treat various diseases, including cancer, infections, and autoimmune diseases. In this study, we engineered natural killer (NK) cells to express S309 single-chain fragment variable (scFv), to target the Spike protein of SARS-CoV-2, hereinafter S309-CAR-NK cells. Our study shows that S309-CAR-NK cells are effective against different SARS-CoV-2 variants, including the B.1.617.2 (Delta), B.1.621 (Mu), and B.1.1.529 (Omicron) variants. The S309-CAR-NK cells can (i) directly bind to SARS-CoV-2 pseudotyped virus (PV), (ii) competitively bind to SARS-CoV-2 PV with 293T cells expressing the human angiotensin converting enzyme 2 (hACE2) receptor (293T-hACE2 cells), (iii) specifically target and lyse A549 cells expressing the spike protein, and (iv) significantly reduce the viral loads of SARS-CoV-2 wild-type (strain USA/WA1/2020) in the lungs of NOD/SCID gamma (NSG) mice expressing hACE2 (hACE2-NSG mice). Altogether, the current study demonstrates the potential use of S309-CAR-NK immunotherapy as an alternative treatment for COVID-19 patients. [ABSTRACT FROM AUTHOR]

Chimeric antigen receptor-natural killer (CAR-NK) cell therapy is a novel immunotherapy targeting cancer cells via the generation of chimeric antigen receptors on NK cells which recognize specific cancer antigens. CAR-NK cell therapy is gaining attention nowadays owing to the ability of CAR-NK cells to release potent cytotoxicity against cancer cells without side effects such as cytokine release syndrome (CRS), neurotoxicity and graft-versus-host disease (GvHD). CAR-NK cells do not require antigen priming, thus enabling them to be used as “off-the-shelf” therapy. Nonetheless, CAR-NK cell therapy still possesses several challenges in eliminating cancer cells which reside in hypoxic and immunosuppressive tumor microenvironment. Therefore, this review is envisioned to explore the current advancements and limitations of CAR-NK cell therapy as well as discuss strategies to overcome the challenges faced by CAR-NK cell therapy. This review also aims to dissect the current status of clinical trials on CAR-NK cells and future recommendations for improving the effectiveness and safety of CAR-NK cell therapy. [ABSTRACT FROM AUTHOR]

Circulating tumor cells (CTCs) are important biomarkers in the development and progression of lung cancer because they can reach other organs through the blood circulation and form distant metastases, exacerbating lung cancer progression. The presence of CTCs is also the main reason for the failure of nanomedicine-based lung cancer treatments. Therefore, magnetic MoSe2 nanosheets loaded with programmed death-ligand 1 (PD-L1), named PD-L1-MFP NS, were employed here to precisely capture lung cancer CTCs in the blood circulation through the tumor-targeting effect of PD-L1 killing CTCs with highly effective photothermal therapy (PTT). In addition, by increasing the expression of cytomegalovirus UL16-binding protein (ULBP) ligands on tumor cells, the PD-L1-MFP NS further activated natural killer (NK) cells and triggered NK cell-induced cancer immunotherapy, thereby enhancing the overall tumor-killing effect. In summary, this material designed to capture CTCs provides a substantial advancement for personalized PTT-triggered immunotherapy and has great clinical translational potential. [ABSTRACT FROM AUTHOR]

BackgroundNatural killer (NK) cells play crucial roles in mediating anti-cancer activity in breast cancer (BRCA). However, the potential of NK cell-related molecules in predicting BRCA outcomes and guiding personalized therapy remains largely unexplored. This study focused on developing a prognostic and therapeutic prediction model for BRCA by incorporating NK cell-related genes.MethodsThe data analyzed primarily originated from the TCGA and GEO databases. The prognostic role of NK cells was evaluated, and marker genes of NK cells were identified via single-cell analysis. Module genes closely associated with immunotherapy resistance were identified by bulk transcriptome-based weighted correlation network analysis (WGCNA). Following taking intersection and LASSO regression, NK-related genes (NKRGs) relevant to BRCA prognosis were screened, and the NK-related prognostic signature was subsequently constructed. Analyses were further expanded to clinicopathological relevance, GSEA, tumor microenvironment (TME) analysis, immune function, immunotherapy responsiveness, and chemotherapeutics. Key NKRGs were screened by machine learning and validated by spatial transcriptomics (ST) and immunohistochemistry (IHC).ResultsTumor-infiltrating NK cells are a favorable prognostic factor in BRCA. By combining scRNA-seq and bulk transcriptomic analyses, we identified 7 NK-related prognostic NKRGs (CCL5, EFHD2, KLRB1, C1S, SOCS3, IRF1, and CCND2) and developed an NK-related risk scoring (NKRS) system. The prognostic reliability of NKRS was verified through survival and clinical relevance analyses across multiple cohorts. NKRS also demonstrated robust predictive power in various aspects, including TME landscape, immune functions, immunotherapy responses, and chemotherapeutic sensitivity. Additionally, KLRB1 and CCND2 emerged as key prognostic NKRGs identified through machine learning and external validation, with their expression correlation with NK cells confirmed in BRCA specimens by ST and IHC.ConclusionsWe developed a novel NK-related gene signature that has proven valuable for evaluating prognosis and treatment response in BRCA, expecting to advance precision medicine of BRCA.

The formation of a lytic immunological synapse (IS) is crucial for cytotoxic lymphocytes to accurately target and effectively eliminate malignant cells. While significant attention has been focused on the lymphocyte side of the IS, particularly its role as a secretory domain for lytic granules, the cancer cell side of the IS has remained relatively underexplored. Recent findings have revealed that cancer cells can rapidly polarize their actin cytoskeleton toward the IS upon interaction with natural killer (NK) cells, thereby evading NK cell-mediated cytotoxicity. In this Brief Research Report, we present preliminary findings suggesting that actin cytoskeleton remodeling at the cancer cell side of the IS is associated with the targeted secretion of small extracellular vesicles towards the interacting NK cell. We observed that multivesicular bodies (MVBs) preferentially accumulate in the synaptic region in cancer cells exhibiting synaptic accumulation of F-actin, compared to those lacking actin cytoskeleton remodeling. Extracellular immunofluorescence staining revealed increased surface exposure of CD63 at the cancer cell side of the IS, suggestive of the fusion of MVBs with the plasma membrane. This hypothesis was supported by a pH-sensitive probe demonstrating dynamic trafficking of CD63 to the extracellular region of the IS. Collectively, our data support the notion that cancer cells can engage in targeted secretion of extracellular vesicles in response to NK cell attack, underscoring the need for further research into the potential role of this process in facilitating cancer cell immune evasion.

Simple Summary: Current therapies are often insufficiently effective in patients with acute myeloid leukemia (AML), prompting ongoing interest in developing new drugs for this aggressive type of blood cancer. Many efforts focus on drugs that target CD33, a cell surface protein that is widely expressed on AML cells. Gemtuzumab ozogamicin (GO), which consists of a CD33 antibody linked to a small molecule toxin, benefits some AML patients but not many others, leaving room for other CD33-targeted therapeutics. Here, we examined CC-96191, a "TriNKET" protein drug that binds CD33 on AML cells at the same time it binds two different proteins, CD16a and NKG2D, on natural killer (NK) cells, thereby activating these immune cells and engaging them to kill AML cells. In preclinical studies, we found CC-96191 to be broadly active against human AML cells that express CD33. CC-96191 activated NK cells but not T cells; while maximum anti-AML efficacy was similar, soluble cytokine levels were 10- to >100-fold lower than with a protein drug that binds CD33 and CD3 on T cells. Moreover, CC-96191 eliminated AML cells but not normal CD33+ monocytes, suggesting selectivity toward leukemic cells. Together, these findings support the clinical exploration of CC-96191 as is currently ongoing. Increasing efforts are focusing on natural killer (NK) cell immunotherapies for AML. Here, we characterized CC-96191, a novel CD33/CD16a/NKG2D immune-modulating TriNKET®. CC-96191 simultaneously binds CD33, NKG2D, and CD16a, with NKG2D and CD16a co-engagement increasing the avidity for, and activation of, NK cells. CC-96191 was broadly active against human leukemia cells in a strictly CD33-dependent manner, with maximal efficacy requiring the co-engagement of CD16a and NKG2D. A frequent CD33 single nucleotide polymorphism, R69G, reduced CC-96191 potency but not maximal activity, likely because of reduced CD33 binding. Similarly, the potency, but not the maximal activity, of CC-96191 was reduced by high concentrations of soluble CD33; in contrast, the soluble form of the NKG2D ligand MICA did not impact activity. In the presence of CD33+ AML cells, CC-96191 activated NK cells but not T cells; while maximum anti-AML efficacy was similar, soluble cytokine levels were 10- to >100-fold lower than with a CD33/CD3 bispecific antibody. While CC-96191-mediated cytolysis was not affected by ABC transporter proteins, it was reduced by anti-apoptotic BCL-2 family proteins. Finally, in patient marrow specimens, CC-96191 eliminated AML cells but not normal monocytes, suggesting selectivity of TriNKET-induced cytotoxicity toward neoplastic cells. Together, these findings support the clinical exploration of CC-96191 as in NCT04789655. [ABSTRACT FROM AUTHOR]

Background: For patients with high grade serous carcinoma of the ovary (HGSC), survival rates have remained static for the last half century. Despite the presence of tumor mutations and infiltration of immune cells, existing immunotherapies have achieved little success against HGSC. These observations highlight a gap in the understanding of how the immune system functions and interacts within HGSC tumors. Methods: We analyzed duplicate core samples from 939 patients with HGSC to understand patterns of immune cell infiltration, localization, and associations with clinical features. We used high-parameter immunohistochemical/Opal multiplex, digital pathology, computational biology, and multivariate analysis to identify immune cell subsets and their associations with HGSC tumors. Results: We defined six patterns of cellular infiltration by spatially restricted unsupervised clustering of cell subsets. Each pattern was represented to some extent in most patient samples, but their specific distributions differed. Overall (OS) and progression-free survival (PFS) corresponded with higher infiltration of CD16a+ cells, and their co-localization with macrophages, T cells, NK cells, in one of six cellular neighborhoods that we defined with our spatial assessment. Conclusions: Immune cell neighborhoods containing CD16a+ cells are associated with improved OS and PFS for patients with HGSC. Patterns of immunologic neighborhoods differentiate patient outcomes, and could inform future, more precise approaches to treatment. [ABSTRACT FROM AUTHOR]

IntroductionNK cells can mediate tumor cell killing by natural cytotoxicity and by antibody-dependent cell-mediated cytotoxicity (ADCC), an anti-tumor mechanism mediated through the IgG Fc receptor CD16A (FcγRIIIA). CD16A polymorphisms conferring increased affinity for IgG positively correlate with clinical outcomes during monoclonal antibody therapy for lymphoma, linking increased binding affinity with increased therapeutic potential via ADCC. We have previously reported on the FcγR fusion CD64/16A consisting of the extracellular region of CD64 (FcγRI), a high-affinity Fc receptor normally expressed by myeloid cells, and the transmembrane/cytoplasmic regions of CD16A, to create a highly potent and novel activating fusion receptor. Here, we evaluate the therapeutic potential of engineered induced pluripotent stem cell (iPSC)-derived NK (iNK) cells expressing CD64/16A as an “off-the-shelf”, antibody-armed cellular therapy product with multi-antigen targeting potential.MethodsiNK cells were generated from iPSCs engineered to express CD64/16A and an interleukin (IL)-15/IL-15Rα fusion (IL-15RF) protein for cytokine independence. iNK cells and peripheral blood NK cells were expanded using irradiated K562-mbIL21–41BBL feeder cells to examine in in vitro and in vivo assays using the Raji lymphoma cell line. ADCC was evaluated in real-time by IncuCyte assays and using a xenograft mouse model with high circulating levels of human IgG.ResultsOur data show that CD64/16A expressing iNK cells can mediate potent anti-tumor activity against human B cell lymphoma. In particular, (i) under suboptimal conditions, including low antibody concentrations and low effector-to-target ratios, iNK-CD64/16A cells mediate ADCC, (ii) iNK-CD64/16A cells can be pre-loaded with tumor-targeting antibodies (arming) to elicit ADCC, (iii) armed iNK-CD64/16A cells can be repurposed with additional antibodies to target new tumor antigens, and (iv) cryopreserved, armed iNK-CD64/16A are capable of sustained ADCC in a tumor xenograft model under saturating levels of human IgG.DiscussioniNK-CD64/16A cells allow for a flexible use of antibodies (antibody arming and antibody targeting), and an “off-the-shelf” platform for multi-antigen recognition to overcome limitations of adoptive cell therapies expressing fixed antigen receptors leading to cancer relapse due to antigen escape variants.

Chimeric antigen receptor-natural killer (CAR-NK) cell therapy is a novel immunotherapy targeting cancer cells via the generation of chimeric antigen receptors on NK cells which recognize specific cancer antigens. CAR-NK cell therapy is gaining attention nowadays owing to the ability of CAR-NK cells to release potent cytotoxicity against cancer cells without side effects such as cytokine release syndrome (CRS), neurotoxicity and graft-versus-host disease (GvHD). CAR-NK cells do not require antigen priming, thus enabling them to be used as “off-the-shelf” therapy. Nonetheless, CAR-NK cell therapy still possesses several challenges in eliminating cancer cells which reside in hypoxic and immunosuppressive tumor microenvironment. Therefore, this review is envisioned to explore the current advancements and limitations of CAR-NK cell therapy as well as discuss strategies to overcome the challenges faced by CAR-NK cell therapy. This review also aims to dissect the current status of clinical trials on CAR-NK cells and future recommendations for improving the effectiveness and safety of CAR-NK cell therapy.

Natural killer (NK) cells play a vital role in xenotransplantation rejection. One approach to induce NK cell immune tolerance is to prevent the NK cell-mediated direct killing of porcine cells by targeting the interaction of the activating receptor NKG2D and its ligands. However, the identity of porcine ligands for the human NKG2D receptor has remained elusive. Previous studies on porcine UL-16 binding protein 1 (pULBP-1) as a ligand for human NKG2D have yielded contradictory results. The goal of the present study was to clarify the role of pULBP-1 in the immune response and its interaction with human NKG2D receptor. To accomplish this, the CRISPR/Cas9 gene editing tool was employed to disrupt the porcine ULBP-1 gene in a 5-gene knockout porcine endothelial cell line (GGTA1, CMAH, β4galNT2, SLA-I α chain, and β-2 microglobulin, 5GKO). A colony with two allele mutations in pULBP-1 was established as a 6-gene knockout pig cell line (6GKO). We found that pULBP-1-deficient pig cells exhibited a reduced binding capacity to human NKG2D-Fc, a recombinant chimera protein. However, the removal of ULBP-1 from porcine endothelial cells did not significantly impact human NK cell degranulation or cytotoxicity upon stimulation with the pig cells. These findings conclusively demonstrate that pULBP-1 is not a crucial ligand for initiating xenogeneic human NK cell activation. [ABSTRACT FROM AUTHOR]

BackgroundFor patients with high grade serous carcinoma of the ovary (HGSC), survival rates have remained static for the last half century. Despite the presence of tumor mutations and infiltration of immune cells, existing immunotherapies have achieved little success against HGSC. These observations highlight a gap in the understanding of how the immune system functions and interacts within HGSC tumors.MethodsWe analyzed duplicate core samples from 939 patients with HGSC to understand patterns of immune cell infiltration, localization, and associations with clinical features. We used high-parameter immunohistochemical/Opal multiplex, digital pathology, computational biology, and multivariate analysis to identify immune cell subsets and their associations with HGSC tumors.ResultsWe defined six patterns of cellular infiltration by spatially restricted unsupervised clustering of cell subsets. Each pattern was represented to some extent in most patient samples, but their specific distributions differed. Overall (OS) and progression-free survival (PFS) corresponded with higher infiltration of CD16a+ cells, and their co-localization with macrophages, T cells, NK cells, in one of six cellular neighborhoods that we defined with our spatial assessment.ConclusionsImmune cell neighborhoods containing CD16a+ cells are associated with improved OS and PFS for patients with HGSC. Patterns of immunologic neighborhoods differentiate patient outcomes, and could inform future, more precise approaches to treatment.

The analysis of immunological parameters during the course of a SARS-CoV-2 infection is of great importance, both to identify diagnostic markers for the risk of a severe course of COVID-19, and to better understand the role of the immune system during the infection. By using multicolor flow cytometry we compared the phenotype of Natural Killer (NK) cells from hospitalized COVID-19 patients during early SARS-CoV-2 infection with samples from recovered and SARS-CoV-2 naïve subjects. Unsupervised high-dimensional analysis of 28-color flow cytometric data revealed a strong enrichment of NKG2C expressing NK cells in response to the acute viral infection. In addition, we found an overrepresentation of highly activated NK cell subsets with an exhausted phenotype. Moreover, our data show long-lasting phenotypic changes within the NK cell compartment that did not completely reverse up to 2 months after recovery. This demonstrates that NK cells are involved in the early innate immune response against SARS-CoV-2. [ABSTRACT FROM AUTHOR]

Natural Killer (NK) cells are a type of innate lymphoid cells that play a crucial role in immunity by killing virally infected or tumor cells and secreting cytokines and chemokines. NK cell-mediated immunotherapy has emerged as a promising approach for cancer treatment due to its safety and effectiveness. NK cell engagers (NKCEs), such as BiKE (bispecific killer cell engager) or TriKE (trispecific killer cell engager), are a novel class of antibody-based therapeutics that exhibit several advantages over other cancer immunotherapies harnessing NK cells. By bridging NK and tumor cells, NKCEs activate NK cells and lead to tumor cell lysis. A growing number of NKCEs are currently undergoing development, with some already in clinical trials. However, there is a need for more comprehensive studies to determine how the molecular design of NKCEs affects their functionality and manufacturability, which are crucial for their development as off-the-shelf drugs for cancer treatment. In this review, we summarize current knowledge on NKCE development and discuss critical factors required for the production of effective NKCEs. [ABSTRACT FROM AUTHOR]

Chitin is a highly abundant N-acetylglucosamine polysaccharide that has been linked to immune responses in the context of fungal infections and allergic asthma, especially to T helper 2 immune responses. Unfortunately, due to the frequent use of crude chitin preparations of unknown purity and degree of polymerization, there is still great uncertainty about how chitin activates different parts of the human immune system. We recently identified chitin oligomers of 6 N-acetylglucosamine units as the smallest immunologically active chitin motif and the innate immune receptor TLR2 as a primary chitin sensor on human and murine myeloid cells, but the response of further immune cells (e.g. lymphoid cells) to oligomeric chitin has not been investigated. Our analysis of primary human immune cells now shows that chitin oligomers activate immune responses of both innate and adaptive lymphocytes: notably, chitin oligomers activated natural killer cells but not B lymphocytes. Moreover, chitin oligomers induced maturation of dendritic cells and enabled potent CD8+ T-cell recall responses. Our results suggest that chitin oligomers not only trigger immediate innate responses in a limited range of myeloid cells but also exert critical activities across the entire human immune system. This highlights chitin oligomer immune activation as an interesting and broadly applicable potential target for both adjuvant development and therapeutic interference in chitin-mediated pathologies. Chitin oligomers are microbe-associated molecular patterns involved in TLR2-dependent fungal recognition by myeloid immune cells. Here we show that lymphoid cells, most notably natural killer cells, are also activated by oligomeric chitin. Oligomeric chitin also promotes antigen-presenting cell maturation and CD8+ T-cell recall responses. Oligomeric chitin, a novel microbe-associated molecular pattern, not only stimulates TLR2-dependent myeloid innate immune cells but also promotes lymphoid innate and adaptive immune responses. [ABSTRACT FROM AUTHOR]

Introduction: Pancreatic cancer is associated with poor prognosis, and limited treatment options are available for the majority of patients. Natural killer (NK) cells in combination with antibodies inducing antibody-dependent cellmediated cytotoxicity (ADCC) could be a highly effective new therapeutic option in pancreatic cancer. Accurate predictive preclinical models are needed to develop successful NK cell immunotherapy. Tumor organoids, in vitro 3D organ-like structures that retain important pathophysiological characteristics of the in vivo tumor, may provide such a model. In the current study, we assessed the cytotoxic potential of adoptive NK cells against human pancreatic cancer organoids. We hypothesized that NK cell anti-tumor responses could be enhanced by including ADCC-triggering antibodies. Methods: We performed cytotoxicity assays with healthy donor-derived IL-2- activated NK cells and pancreatic cancer organoids from four patients. A 3D cytotoxicity assay using live-cell-imaging was developed and enabled real-time assessment of the response. Results: We show that NK cells migrate to and target pancreatic cancer organoids, resulting in an increased organoid death, compared to the no NK cell controls (reaching an average fold change from baseline of 2.1±0.8 vs 1.4 ±0.6). After 24-hours of co-culture, organoid 2D growth increased. Organoids from 2 out of 4 patients were sensitive to NK cells, while organoids from the other two patients were relatively resistant, indicating patient-specific heterogeneity among organoid cultures. The ADCC-inducing antibodies avelumab (anti-PD-L1) and trastuzumab (anti-HER2) increased NK cell-induced organoid cell death (reaching an average fold change from baseline of 3.5±1.0 and 4.5±1.8, respectively). Moreover, combination therapy with avelumab or trastuzumab resulted in complete disintegration of organoids. Finally, inclusion of ADCC-inducing antibodies was able to overcome resistance in NK-organoid combinations with low or no kill. Discussion: These results support the use of organoids as a relevant and personalized model to study the anti-tumor response of NK cells in vitro and the potential of ADCC-inducing antibodies to enhance NK cell effector function. [ABSTRACT FROM AUTHOR]

Background: Natural killer (NK) cells are crucial to the emergence, identification, and prognosis of cancers. The roles of NK cell-related genes in the tumor immune microenvironment (TIME) and immunotherapy treatment are unclear. Triple-negative breast cancer (TNBC) is a highly aggressive malignant tumor. Hence, this study was conducted to develop a reliable risk model related to NK cells and provide a novel system for predicting the prognosis of TNBC. Methods: NK cell-related genes were collected from previous studies. Based on TCGA and GEO database, univariate and LASSO cox regression analysis were used to establish the NK cell-related gene signature. The patients with TNBC were separated to high-risk and low-risk groups. After that, survival analysis was conducted and the responses to immunotherapies were evaluated on the basis of the signature. Moreover, the drug sensitivity of some traditional chemotherapeutic drugs was assessed by using the "oncoPredict" R package. In addition, the expression levels of the genes involved in the signature were validated by using qRT-PCR in TNBC cell lines. Results: The patients with TNBC were divided into high- and low-risk groups according to the median risk score of the 5-NK cell-related gene signature. The low-risk group was associated with a better clinical outcome. Besides, the differentially expressed genes between the different risk groups were enriched in the biological activities associated with immunity. The tumor immune cells were found to be highly infiltrated in the low-risk groups. In accordance with the TIDE score and immune checkpoint-related gene expression analysis, TNBC patients in the low-risk groups were suggested to have better responses to immunotherapies. Eventually, some classical anti-tumor drugs were shown to be less effective in high-risk groups than in low-risk groups. Conclusion: The 5-NK cell-related gene signature exhibit outstanding predictive performance and provide fresh viewpoints for evaluating the success of immunotherapy. It will provide new insights to achieve precision and integrated treatment for TNBC in the future. [ABSTRACT FROM AUTHOR]

The signal transducer and activator of transcription 3 (STAT3) signaling pathway is a key mediator of cancer cell proliferation, survival, and invasion. We discovered YHO-1701 as a small molecule inhibitor of STAT3 dimerization and demonstrated its potent anti-tumor activity using xenograft mouse models as monotherapy and combination therapy with molecular targeted drugs. STAT3 is also associated with cancer immune tolerance; therefore, we used the female CT26 syngeneic mouse model to examine the effect of combining YHO-1701 administration with PD-1/PD-L1 blockade. Pretreatment of the mice with YHO-1701 before starting anti-PD-1 antibody administration resulted in a significant therapeutic effect. In addition, the effect of monotherapy and combination treatment with YHO-1701 was significantly abolished by depleting natural killer (NK) cell activity. YHO-1701 was also found to restore the activity of mouse NK cells under inhibitory conditions in vitro. Furthermore, this combination therapy significantly inhibited tumor growth in an immunotherapy-resistant model of murine CMS5a fibrosarcoma. These results suggest that the combination of YHO-1701 with PD-1/PD-L1 blockade might be a new candidate for cancer immunotherapy involving the enhancement of NK cell activity in the tumor microenvironment. [ABSTRACT FROM AUTHOR]

Introduction: Increasing evidence has shown that coronavirus disease 19 (COVID-19) severity is driven by a dysregulated immunological response. Previous studies have demonstrated that natural killer (NK) cell dysfunction underpins severe illness in COVID-19 patients, but have lacked an in-depth analysis of NK cell markers as a driver of death in the most critically ill patients. Methods: We enrolled 50 non-vaccinated hospitalized patients infected with the initial virus or the alpha variant of SARS-CoV-2 with moderate or severe illness, to evaluate phenotypic and functional features of NK cells. Results: Here, we show that, consistent with previous studies, evolution NK cells from COVID-19 patients are more activated, with the decreased activation of natural cytotoxicity receptors and impaired cytotoxicity and IFN-g production, in association with disease regardless of the SARS-CoV-2 strain. Fatality was observed in 6 of 17 patients with severe disease; NK cells from all of these patients displayed a peculiar phenotype of an activated memory-like phenotype associated with massive TNF-a production. Discussion: These data suggest that fatal COVID-19 infection is driven by an uncoordinated inflammatory response in part mediated by a specific subset of activated NK cells. [ABSTRACT FROM AUTHOR]

The analysis of immunological parameters during the course of a SARS-CoV-2 infection is of great importance, both to identify diagnostic markers for the risk of a severe course of COVID-19, and to better understand the role of the immune system during the infection. By using multicolor flow cytometry we compared the phenotype of Natural Killer (NK) cells from hospitalized COVID-19 patients during early SARS-CoV-2 infection with samples from recovered and SARS-CoV-2 naïve subjects. Unsupervised high-dimensional analysis of 28-color flow cytometric data revealed a strong enrichment of NKG2C expressing NK cells in response to the acute viral infection. In addition, we found an overrepresentation of highly activated NK cell subsets with an exhausted phenotype. Moreover, our data show long-lasting phenotypic changes within the NK cell compartment that did not completely reverse up to 2 months after recovery. This demonstrates that NK cells are involved in the early innate immune response against SARS-CoV-2.

Abstract The efficacy and specificity of conventional monoclonal antibody (mAb) drugs in the clinic require further improvement. Currently, the development and application of novel antibody formats for improving cancer immunotherapy have attracted much attention. Variable region‐retaining antibody fragments, such as antigen‐binding fragment (Fab), single‐chain variable fragment (scFv), bispecific antibody, and bi/trispecific cell engagers, are engineered with humanization, multivalent antibody construction, affinity optimization and antibody masking for targeting tumor cells and killer cells to improve antibody‐based therapy potency, efficacy and specificity. In this review, we summarize the application of antibody variable region engineering and discuss the future direction of antibody engineering for improving cancer therapies.

IntroductionPancreatic cancer is associated with poor prognosis, and limited treatment options are available for the majority of patients. Natural killer (NK) cells in combination with antibodies inducing antibody-dependent cell-mediated cytotoxicity (ADCC) could be a highly effective new therapeutic option in pancreatic cancer. Accurate predictive preclinical models are needed to develop successful NK cell immunotherapy. Tumor organoids, in vitro 3D organ-like structures that retain important pathophysiological characteristics of the in vivo tumor, may provide such a model. In the current study, we assessed the cytotoxic potential of adoptive NK cells against human pancreatic cancer organoids. We hypothesized that NK cell anti-tumor responses could be enhanced by including ADCC-triggering antibodies.MethodsWe performed cytotoxicity assays with healthy donor-derived IL-2-activated NK cells and pancreatic cancer organoids from four patients. A 3D cytotoxicity assay using live-cell-imaging was developed and enabled real-time assessment of the response.ResultsWe show that NK cells migrate to and target pancreatic cancer organoids, resulting in an increased organoid death, compared to the no NK cell controls (reaching an average fold change from baseline of 2.1±0.8 vs 1.4±0.6). After 24-hours of co-culture, organoid 2D growth increased. Organoids from 2 out of 4 patients were sensitive to NK cells, while organoids from the other two patients were relatively resistant, indicating patient-specific heterogeneity among organoid cultures. The ADCC-inducing antibodies avelumab (anti-PD-L1) and trastuzumab (anti-HER2) increased NK cell-induced organoid cell death (reaching an average fold change from baseline of 3.5±1.0 and 4.5±1.8, respectively). Moreover, combination therapy with avelumab or trastuzumab resulted in complete disintegration of organoids. Finally, inclusion of ADCC-inducing antibodies was able to overcome resistance in NK-organoid combinations with low or no kill.DiscussionThese results support the use of organoids as a relevant and personalized model to study the anti-tumor response of NK cells in vitro and the potential of ADCC-inducing antibodies to enhance NK cell effector function.

IntroductionIncreasing evidence has shown that coronavirus disease 19 (COVID-19) severity is driven by a dysregulated immunological response. Previous studies have demonstrated that natural killer (NK) cell dysfunction underpins severe illness in COVID-19 patients, but have lacked an in-depth analysis of NK cell markers as a driver of death in the most critically ill patients.MethodsWe enrolled 50 non-vaccinated hospitalized patients infected with the initial virus or the alpha variant of SARS-CoV-2 with moderate or severe illness, to evaluate phenotypic and functional features of NK cells.ResultsHere, we show that, consistent with previous studies, evolution NK cells from COVID-19 patients are more activated, with the decreased activation of natural cytotoxicity receptors and impaired cytotoxicity and IFN-γ production, in association with disease regardless of the SARS-CoV-2 strain. Fatality was observed in 6 of 17 patients with severe disease; NK cells from all of these patients displayed a peculiar phenotype of an activated memory-like phenotype associated with massive TNF-α production.DiscussionThese data suggest that fatal COVID-19 infection is driven by an uncoordinated inflammatory response in part mediated by a specific subset of activated NK cells.

Introduction: Methimazole (MMI) represents the conventional therapeutic agent for Graves' disease (GD) hyperthyroidism, but MMI efficacy is limited since it marginally affects the underlying autoimmune process. In a previous study, we randomly assigned 42 newly diagnosed GD patients with insufficient vitamin D (VitD) and selenium (Se) levels to treatment with MMI alone (standard) or combined with selenomethionine and cholecalciferol (intervention) and observed a prompter resolution of hyperthyroidism in the intervention group. Methods: In the present study, we aimed to explore changes in peripheral T regulatory (Treg) and circulating natural killer (NK) cell frequency, circulating NK cell subset distribution and function, during treatment. Results: At baseline, circulating total CD3-CD56+NK cells and CD56bright NK cells were significantly higher in GD patients than in healthy controls (HC) (15.7 ± 9.6% vs 9.9 ± 5.6%, p=0.001; 12.2 ± 10.3% vs 7.3 ± 4.1%, p=0.02, respectively); no differences emerged in Treg cell frequency. Frequencies of total NK cells and CD56bright NK cells expressing the activation marker CD69 were significantly higher in GD patients than in HC, while total NK cells and CD56dim NK cells expressing CD161 (inhibitory receptor) were significantly lower. When cocultured with the K562 target cell, NK cells from GD patients had a significantly lower degranulation ability compared to HC (p<0.001). Following 6 months of treatment, NK cells decreased in both the intervention and MMI-alone groups, but significantly more in the intervention group (total NK: -10.3%, CI 95% -15.8; -4.8% vs -3.6%, CI 95% -9; 1.8%, p=0.09 and CD56bright NK cells: -6.5%, CI 95% -10.1; -3 vs -0.9%, CI 95% -4.4; 2%, p=0.03). Compared to baseline, CD69+ NK cells significantly decreased, while degranulation ability slightly improved, although no differences emerged between the two treatment groups. Compared to baseline, Treg cell frequency increased exclusively in the intervention group (+1.1%, CI 95% 0.4; 1.7%). Discussion: This pilot study suggested that VitD and Se supplementation, in GD patients receiving MMI treatment, modulates Treg and NK cell frequency, favoring a more pronounced reduction of NK cells and the increase of Treg cells, compared to MMI alone. Even if further studies are needed, it is possible to speculate that this immunomodulatory action might have facilitated the prompter and better control of hyperthyroidism in the supplemented group observed in the previous study. [ABSTRACT FROM AUTHOR]

IntroductionMethimazole (MMI) represents the conventional therapeutic agent for Graves’ disease (GD) hyperthyroidism, but MMI efficacy is limited since it marginally affects the underlying autoimmune process. In a previous study, we randomly assigned 42 newly diagnosed GD patients with insufficient vitamin D (VitD) and selenium (Se) levels to treatment with MMI alone (standard) or combined with selenomethionine and cholecalciferol (intervention) and observed a prompter resolution of hyperthyroidism in the intervention group.MethodsIn the present study, we aimed to explore changes in peripheral T regulatory (Treg) and circulating natural killer (NK) cell frequency, circulating NK cell subset distribution and function, during treatment.ResultsAt baseline, circulating total CD3-CD56+NK cells and CD56bright NK cells were significantly higher in GD patients than in healthy controls (HC) (15.7 ± 9.6% vs 9.9 ± 5.6%, p=0.001; 12.2 ± 10.3% vs 7.3 ± 4.1%, p=0.02, respectively); no differences emerged in Treg cell frequency. Frequencies of total NK cells and CD56bright NK cells expressing the activation marker CD69 were significantly higher in GD patients than in HC, while total NK cells and CD56dim NK cells expressing CD161 (inhibitory receptor) were significantly lower. When co-cultured with the K562 target cell, NK cells from GD patients had a significantly lower degranulation ability compared to HC (p

Natural killer (NK) cells have emerged as key mediators of obesity-related adipose tissue inflammation. However, the phenotype of NK cell subsets residing in human adipose tissue are poorly defined, preventing a detailed understanding of their role in metabolic disorders. In this study, we applied multicolor flow cytometry to characterize CD56bright and CD56dim NK cells in blood and adipose tissue depots in individuals with obesity and identified surface proteins enriched on adipose tissue-resident CD56bright NK cells. Particularly, we found that adipose tissue harbored clusters of tissue-resident CD56bright NK cells signatured by the expression of CD26, CCR5 and CD63, possibly reflecting an adaptation to the microenvironment. Together, our findings provide broad insights into the identity of NK cells in blood and adipose tissue in relation to obesity.

Natural killer (NK) cells have emerged as a major target for cancer immunotherapies, particularly as cellular therapy modalities because they have relatively less toxicity than T lymphocytes. However, NK cell-based therapy suffers from many challenges, including problems with its activation, resistance to genetic engineering, and large-scale expansion needed for therapeutic purposes. Recently, nanobiomaterials have emerged as a promising solution to control the challenges associated with NK cells. This focused review summarises the recent advances in the field and highlights current and future perspectives of using nanobiomaterials to maximise anticancer responses of NK cells for safe and effective immunotherapy. Finally, we provide our opinion on the role of smart materials in activating NK cells as a potential cellular therapy of the future. Natural killer (NK) cells have the potential to directly lyse cancer cells, resulting in enhanced immunoprotection against tumour cells. The therapeutic potential of NK cells against tumour cells can be augmented using different activating signalling pathways on NK cells. However, to achieve translation goals, the poor expansion and proliferation of NK cells should be addressed. Emerging materials with their multifaceted properties and biocompatibility have demonstrated promising results to augment NK cell functions such as their expansion, activation, and migration toward tumour sites, showing a promising future for nanobiomaterials in the field of cancer immunotherapy. [ABSTRACT FROM AUTHOR]

Introduction: Studies of NK cells in tumors have primarily focused on their direct actions towards tumor cells. We evaluated the impact of NK cells on expression of homing receptor ligands on tumor vasculature, intratumoral T cell number and function, and T cell activation in tumor draining lymph node. Methods: Using an implantable mouse model of melanoma, T cell responses and homing receptor ligand expression on the vasculature were evaluated with and without NK cells present during the early stages of the tumor response by flow cytometry. Results: NK cells in early-stage tumors are one source of IFNg that augments homing receptor ligand expression. More significantly, NK cell depletion resulted in increased numbers of intratumoral T cells with an anergic phenotype. Anergic T cell development in tumor draining lymph node was associated with increased T-cell receptor signaling but decreased proliferation and effector cell activity, and an incomplete maturation phenotype of antigen presenting cells. These effects of NK depletion were similar to those of blocking CD40L stimulation. Discussion: We conclude that an important function of NK cells is to drive proper APC maturation via CD40L during responses to early-stage tumors, reducing development of anergic T cells. The reduced development of anergic T cells resulting in improved tumor control and T cell responses when NK cells were present. [ABSTRACT FROM AUTHOR]

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Objective: Small cell lung cancer (SCLC) is commonly recognized as the most fatal lung cancer type. Despite substantial advances in immune checkpoint blockade therapies for treating solid cancers, their benefits are limited to a minority of patients with SCLC. In the present study, novel indicators for predicting the outcomes and molecular targets for SCLC treatment were elucidated., Methods: We conducted bioinformatics analysis to identify the key genes associated with tumor-infiltrating lymphocytes in SCLC. The functional role of the key gene identified in SCLC was determined both in vitro and in vivo ., Results: A significant correlation was observed between patient survival and CD56dim natural killer (NK) cell proportion. Furthermore, we noted that the hub gene ubiquitin-specific protease 1 (USP1) is closely correlated with both CD56dim NK cells and overall survival in SCLC. Bioinformatics analysis revealed that USP1 is upregulated in SCLC. In addition, gene set enrichment analysis revealed that USP1 overexpression hinders NK cell-mediated immune responses. By co-cultivating NK-92 cells with SCLC cells, we demonstrated that NK cell cytotoxicity against SCLC could be improved either via USP1 knock-down or pharmacological inhibition. Furthermore, using a nude-mice xenograft tumor model, we noted that USP1 inhibition effectively suppressed tumor proliferation and increased the expression of NK cell-associated markers., Conclusions: Our study findings highlight the importance of NK cells in regulating SCLC. USP1 overexpression can inhibit NK cell-mediated immunity; therefore, USP1 may serve not only as a prognostic biomarker but also as a potential molecular target of SCLC therapy., Competing Interests: The authors declare no conflicts of interest to report regarding the present study., (© 2025 The Authors.)

IntroductionStudies of NK cells in tumors have primarily focused on their direct actions towards tumor cells. We evaluated the impact of NK cells on expression of homing receptor ligands on tumor vasculature, intratumoral T cell number and function, and T cell activation in tumor draining lymph node.MethodsUsing an implantable mouse model of melanoma, T cell responses and homing receptor ligand expression on the vasculature were evaluated with and without NK cells present during the early stages of the tumor response by flow cytometry.ResultsNK cells in early-stage tumors are one source of IFNγ that augments homing receptor ligand expression. More significantly, NK cell depletion resulted in increased numbers of intratumoral T cells with an anergic phenotype. Anergic T cell development in tumor draining lymph node was associated with increased T-cell receptor signaling but decreased proliferation and effector cell activity, and an incomplete maturation phenotype of antigen presenting cells. These effects of NK depletion were similar to those of blocking CD40L stimulation.DiscussionWe conclude that an important function of NK cells is to drive proper APC maturation via CD40L during responses to early-stage tumors, reducing development of anergic T cells. The reduced development of anergic T cells resulting in improved tumor control and T cell responses when NK cells were present.

Natural killer (NK) cells are an important component of the innate immune system, and have a key role in host defense against infection and in tumor surveillance. Tumors and viruses employ remarkably similar strategies to avoid recognition and killing by NK cells and so much can be learnt by comparing NK cells in these disparate diseases. The lung is a unique tissue environment and immune cells in this organ, including NK cells, exist in a hypofunctional state to prevent activation against innocuous stimuli. Upon infection, rapid NK cell infiltration into the lung occurs, the amplitude of which is determined by the extent of inflammation and damage. Activated NK cells kill infected cells and produce proinflammatory cytokines and chemokines to recruit cells of the adaptive immune system. More recent evidence has shown that NK cells also play an additional role in resolution of inflammation. In lung cancer however, NK cell recruitment is impaired and those that are present have reduced functionality. The majority of lung NK cells are circulatory, however recently a small population of tissue-resident lung NK cells has been described. The specific role of this subset is yet to be determined, but they show similarity to resident memory T cell subsets. Whether resident or recruited, NK cells are important in the control of pulmonary infections, but equally, can drive excessive inflammation if not regulated. In this review we discuss how NK cells are recruited, controlled and retained in the specific environment of the lung in health and disease. Understanding these mechanisms in the context of infection may provide opportunities to promote NK cell recruitment and function in the lung tumor setting. [ABSTRACT FROM AUTHOR]

Natural killer (NK) cells play an important role in recognizing and killing pathogen-infected or malignant cells. Changes in their numbers or activation can contribute to several diseases and pathologies including systemic sclerosis (SSc), an autoimmune disease characterized by inflammation and tissue remodeling. In these patients, increased expression of the AP-1 transcription factor, Fra-2 was reported. In mice ectopic overexpression of Fra-2 (TG) leads to SSc with strong pulmonary fibrosis, pulmonary hypertension, and inflammation. Analysis of the underlying immune cell profile in the lungs of young TG mice, which do not yet show any signs of lung disease, revealed increased numbers of eosinophils and T cells but strongly reduced NK numbers. Therefore, we aimed to identify the cause of the absence of NK cells in the lungs of these mice and to determine the potential role of Fra-2 in NK development. Examination of inflammatory cell distribution in TG mice revealed similar NK deficiencies in the spleen, blood, and bone marrow. Deeper analysis of the WT and TG bone marrow revealed a potential NK cell developmental defect beginning at the preNKP stage. To determine whether this defect was cell-intrinsic or extrinsic, mixed bone marrow chimera and in vitro differentiation experiments were performed. Both experiments showed that the defect caused by Fra-2 was primarily cell-intrinsic and minimally dependent on the environment. Closer examination of surface markers and transcription factors required for NK development, revealed the expected receptor distribution but changes in transcription factor expression. We found a significant reduction in Nfil3, which is essential for the transition of common lymphoid cells to NK committed precursor cells and an AP-1 binding site in the promotor of this gene. In Summary, our data demonstrates that regulation of Fra-2 is essential for NK development and maturation, and suggests that the early NK dysfunction plays an important role in the pathogenesis of systemic sclerosis. [ABSTRACT FROM AUTHOR]

Background: To explore the feasibility and safety of natural killer (NK) cell therapy in HCC, we performed a prospective, open-label, phase I trial to evaluate the synergistic effect of locoregional high-dose autologous NK cell therapy in combination with hepatic arterial infusion chemotherapy (HAIC). Methods: Patients with locally advanced HCC who were refractory to the standard treatment were eligible for this study. Patients received expanded and activated NK cells for 5 consecutive days in a dose-escalating manner (dose 2.5×108, 5×108, 10×108 NK cells/injection) through hepatic arterial infusion following 4 cycles of HAIC with 5-fluorouracil (750 mg/m2) and cisplatin (25 mg/m2). The primary endpoint was the safety of NK cell-based immunotherapy, and the secondary endpoints were objective response rate (ORR), progression-free survival (PFS), overall survival (OS), and immunologic responses. Results: Of the 11 patients enrolled, the confirmed ORR was 63.6% (complete response [CR]: 36.4%, confirmed partial response [PR]: 27.3%). Stable disease (SD) and progressive disease (PD) were observed in two patients (18.2%) each, resulting in a disease control rate (DCR) of 81.8%. The median PFS and OS were 10.3 and 41.6 months, respectively. There were no incidences of decompensation or severe adverse events during HAIC, and no adverse events related to NK cell infusion were noted. Conclusion: The combination of HAIC and locoregional high-dose NK cell therapy is a safe and effective treatment for locally advanced HCC patients who were refractory to the standard treatment. This result warrants further development of this novel treatment to establish its efficacy in HCC. [ABSTRACT FROM AUTHOR]

The development of BCR-ABL1 tyrosine kinase inhibitors (TKIs) markedly improved the prognosis of patients with chronic myeloid leukemia (CML). Approximately 50% of patients who achieve deep molecular response (DMR) remain in treatment-free remission (TFR) even after discontinuation of TKIs. Although TKIs may achieve clinical “cure” after TKI treatment for specific periods, there are no reliable biomarkers for predicting the response to TKIs and the probability of TFR in CML. An increase in natural killer (NK) cells in the peripheral blood of TKI-treated CML patients is correlated with better outcomes, suggesting that TKIs induce antitumor NK cell immunity against CML cells. Killer immunoglobulin-like receptors (KIRs) are highly polymorphic NK cell receptors that play important roles in the regulation of immune responses. The identification of allelic polymorphisms of KIRs by next-generation sequencing uncovered novel aspects of KIRs. Here we summarize the current knowledge of the genetic and immunological aspects of KIRs and discuss the association between allelic polymorphisms of KIRs and TKI-treated CML.

Natural killer (NK) cells are an important component of the innate immune system, and have a key role in host defense against infection and in tumor surveillance. Tumors and viruses employ remarkably similar strategies to avoid recognition and killing by NK cells and so much can be learnt by comparing NK cells in these disparate diseases. The lung is a unique tissue environment and immune cells in this organ, including NK cells, exist in a hypofunctional state to prevent activation against innocuous stimuli. Upon infection, rapid NK cell infiltration into the lung occurs, the amplitude of which is determined by the extent of inflammation and damage. Activated NK cells kill infected cells and produce pro-inflammatory cytokines and chemokines to recruit cells of the adaptive immune system. More recent evidence has shown that NK cells also play an additional role in resolution of inflammation. In lung cancer however, NK cell recruitment is impaired and those that are present have reduced functionality. The majority of lung NK cells are circulatory, however recently a small population of tissue-resident lung NK cells has been described. The specific role of this subset is yet to be determined, but they show similarity to resident memory T cell subsets. Whether resident or recruited, NK cells are important in the control of pulmonary infections, but equally, can drive excessive inflammation if not regulated. In this review we discuss how NK cells are recruited, controlled and retained in the specific environment of the lung in health and disease. Understanding these mechanisms in the context of infection may provide opportunities to promote NK cell recruitment and function in the lung tumor setting.

Natural killer (NK) cells play an important role in recognizing and killing pathogen-infected or malignant cells. Changes in their numbers or activation can contribute to several diseases and pathologies including systemic sclerosis (SSc), an autoimmune disease characterized by inflammation and tissue remodeling. In these patients, increased expression of the AP-1 transcription factor, Fra-2 was reported. In mice ectopic overexpression of Fra-2 (TG) leads to SSc with strong pulmonary fibrosis, pulmonary hypertension, and inflammation. Analysis of the underlying immune cell profile in the lungs of young TG mice, which do not yet show any signs of lung disease, revealed increased numbers of eosinophils and T cells but strongly reduced NK numbers. Therefore, we aimed to identify the cause of the absence of NK cells in the lungs of these mice and to determine the potential role of Fra-2 in NK development. Examination of inflammatory cell distribution in TG mice revealed similar NK deficiencies in the spleen, blood, and bone marrow. Deeper analysis of the WT and TG bone marrow revealed a potential NK cell developmental defect beginning at the preNKP stage. To determine whether this defect was cell-intrinsic or extrinsic, mixed bone marrow chimera and in vitro differentiation experiments were performed. Both experiments showed that the defect caused by Fra-2 was primarily cell-intrinsic and minimally dependent on the environment. Closer examination of surface markers and transcription factors required for NK development, revealed the expected receptor distribution but changes in transcription factor expression. We found a significant reduction in Nfil3, which is essential for the transition of common lymphoid cells to NK committed precursor cells and an AP-1 binding site in the promotor of this gene. In Summary, our data demonstrates that regulation of Fra-2 is essential for NK development and maturation, and suggests that the early NK dysfunction plays an important role in the pathogenesis of systemic sclerosis.

Natural killer cells constitute a part of the innate immune system that mediates an effective immune response towards virus-infected and malignant cells. In recent years, research has focused on exploring and advancing NK cells as an active immunotherapy platform. Despite major advances, there are several key challenges that need to be addressed for the effective translation of NK cell research to clinical applications. This review highlights some of these challenges and the innovative strategies being developed to overcome them, including in vitro expansion, in vivo persistence, infiltration to the tumor site, and prevention of exhaustion. [ABSTRACT FROM AUTHOR]

The versatility of natural killer cells has ignited growing interest in their therapeutic use for cancer and other immunotherapy treatments. However, NK cells compose a small portion of peripheral blood mononuclear cells (5%–20% of PBMCs) and clinical doses require billions of cells. Manufacturing suitable doses of NK cells remains a major challenge for NK immunotherapy. The current standard for expanding NK cells relies on feeder cells and fetal bovine serum to achieve large expansion, but both encounter regulatory concerns. We developed NK Cloudz, a dissolvable polymer-based microsphere platform, as an alternative to a feeder cell approach to expand NK cells. We demonstrated that a combination of NK Cloudz, a G-Rex6M culture vessel, and GMP Human Platelet Lysate expanded NK cells 387 ± 100-fold in 10 days from a PBMC starting population. The NK purity, viability, and cytotoxicity were similar to both a feeder cell protocol and an FBS-based protocol. Additionally, we found no significant differences between FBS and GMP Human Platelet Lysate and concluded that platelet lysate is a good xeno-free alternative to FBS for NK expansion. Overall, we demonstrated a feeder-cell-free and FBS-free protocol that leverages NK Cloudz as a promising step toward a commercial GMP manufacturing method to expand NK cells for therapeutic use. [ABSTRACT FROM AUTHOR]

The versatility of natural killer cells has ignited growing interest in their therapeutic use for cancer and other immunotherapy treatments. However, NK cells compose a small portion of peripheral blood mononuclear cells (5%–20% of PBMCs) and clinical doses require billions of cells. Manufacturing suitable doses of NK cells remains a major challenge for NK immunotherapy. The current standard for expanding NK cells relies on feeder cells and fetal bovine serum to achieve large expansion, but both encounter regulatory concerns. We developed NK Cloudz, a dissolvable polymer-based microsphere platform, as an alternative to a feeder cell approach to expand NK cells. We demonstrated that a combination of NK Cloudz, a G-Rex6M culture vessel, and GMP Human Platelet Lysate expanded NK cells 387 ± 100-fold in 10 days from a PBMC starting population. The NK purity, viability, and cytotoxicity were similar to both a feeder cell protocol and an FBS-based protocol. Additionally, we found no significant differences between FBS and GMP Human Platelet Lysate and concluded that platelet lysate is a good xeno-free alternative to FBS for NK expansion. Overall, we demonstrated a feeder-cell-free and FBS-free protocol that leverages NK Cloudz as a promising step toward a commercial GMP manufacturing method to expand NK cells for therapeutic use.