NK Cell-Based Immunotherapy in Cancer Metastasis

Natural killer cells: the immune frontline against circulating tumor cells

Natural killer (NK) play a key role in controlling tumor dissemination by mediating cytotoxicity towards cancer cells without the need of education. These cells are pivotal in eliminating circulating tumor cells (CTCs) from the bloodstream, thus limiting cancer spread and metastasis. However, aggressive CTCs can evade NK cell surveillance, facilitating tumor growth at distant sites. In this review, we first discuss the biology of NK cells, focusing on their functions within the tumor microenvironment (TME), the lymphatic system, and circulation. We then examine the immune evasion mechanisms employed by cancer cells to inhibit NK cell activity, including the upregulation of inhibitory receptors. Finally, we explore the clinical implications of monitoring circulating biomarkers, such as NK cells and CTCs, for therapeutic decision-making and emphasize the need to enhance NK cell-based therapies by overcoming immune escape mechanisms.

Advances and potentials in platelet-circulating tumor cell crosstalk

Tumor metastasis leads to circulating tumor cells (CTCs) that separate from primary malignant tumors and enter blood circulation. CTCs survive and engage with other cells to cope with obstacles, including shear stress, disease, immune attacks, and drugs. Platelets are the best partners for CTCs. Platelets provide a good protective layer for CTCs to ensure that are not monitored and cleared by the native immune system, and protected from shear stress and survive better. Here, we review current reports on platelet-CTC interaction and the clinical relevance of their combination and summarize new techniques for CTC capture and treatment based on platelet-CTC interaction. We discuss current data, identify its shortcomings, and suggest future developments.

CD56bright cytokine-induced memory-like NK cells and NK-cell engagers synergize against non-small cell lung cancer cancer-stem cells

BACKGROUND

Due to their enhanced responsiveness and persistence, cytokine-induced memory-like (CIML)-natural killer (NK) cells have emerged as new immunotherapeutic tools against malignancies. However, their effects on tumor-cell spread and metastases in solid tumors remain poorly investigated. Moreover, a clear identification of the most effective CIML-NK subsets, especially in controlling cancer stem cells (CSC), is still lacking.

METHODS

We performed combined phenotypical and functional analyses of CIML-NK cell subsets, either selected by flow-cytometry gating, or generated from sorted CD56bright/CD56dim NK cells.By co-culture experiments, we analyzed the effect of CIML-NK cells on non-small cell lung cancer (NSCLC) cell spheroids, or patient-derived xenografts (PDX), assessing changes in their CSC content, tumorigenicity, and/or tumor disseminating capability in vivo. CIML-NK cells were also infused in PDX-bearing mice to validate their effect on the CSC dissemination from the PDX to the lungs.Finally, we generated and functionally analyzed CIML-NK cells from patients with stages I/III NSCLC (n=6).

RESULTS

We show that CIML-NK cells exert antitumor activity mostly through their CD56bright cell subset, which greatly expands during CIML differentiation. Compared with NK cells conventionally activated with interleukin-2, CIML-NK cells express lower levels of check-point receptors, TIGIT and TIM3, and higher effector functions against NSCLC cells from PDX, and against in vitro-generated tumor spheroids. Remarkably, CIML-NK cells also significantly reduce the CSC-containing CD133+ cell subpopulation within spheroids and PDX, and limit tumor cell tumorigenicity and ability to disseminate CSCs from primary tumors to distant sites. Sorting experiments on CIML or tumor cell subsets reveal that CD56bright cells drive most of this anti-CSC activity, and suggest that such functional advantage could be related to increased expression of LFA-1 and ICAM-1 on CD56bright cells and CSCs, respectively. We also show that the tri-specific killer cell engager (TriKE) 1615133 significantly enhances CIML-NK cell activity against CSCs. Finally, we demonstrate that CIML-NK cells, capable of killing autologous tumor cells and responding to the 1615133 TriKE, could be induced from patients with NSCLC.

CONCLUSIONS

Our study discloses for the first time the therapeutic potential of CIML-NK cells in controlling CSCs and metastatic spread, highlighting the role of the CD56bright subset expansion and 1615133 TriKE for optimizing CIML-NK-based therapies against metastatic tumors.

Profiling Breast Tumor Heterogeneity and Identifying Breast Cancer Subtypes Through Tumor-Associated Immune Cell Signatures and Immuno Nano Sensors

Breast cancer is a complex and heterogeneous disease with varying cellular, genetic, epigenetic, and molecular expressions. The detection of intratumor heterogeneity in breast cancer poses significant challenges due to its complex multifaceted characteristics, yet its identification is crucial for guiding effective treatment decisions and understanding the disease progression. Currently, there exists no method capable of capturing the full extent of breast tumor heterogeneity. In this study, the aim is to identify and characterize metabolic heterogeneity in breast tumors using immune cells and an ultrafast laser-fabricated Immuno Nano Sensor. Combining spectral markers from both Natural Killer (NK) and T cells, a machine-learning approach is implemented to distinguish cancer from healthy samples, identify primary versus metastatic tumors, and determine estrogen receptor (ER)/progesterone receptor (PR) status at the single-cell level. The platform successfully distinguished heterogeneous breast cancer samples from healthy individuals, achieving 97.8% sensitivity and 92.2% specificity, and accurately identified primary tumors from metastatic tumors. Characteristic spectral signatures allow for discrimination between ER/PR-positive and negative tumors with 97.5% sensitivity. This study demonstrates the potential of immune cell-based metabolic profiling in providing a comprehensive assessment of breast tumor heterogeneity and paving the way for minimally invasive liquid biopsy approaches in breast cancer diagnosis and management.

Lymphocyte subsets in pediatric acute lymphoblastic leukemia and their prognostic value

To study the changes of lymphocyte subsets in children with acute lymphoblastic leukemia (ALL) at initial diagnosis and compare them with those of healthy children and patients who have achieved complete remission (CR). Furthermore, we aim to analyze the prognostic significance of lymphocyte subsets in these patients. From May 2011 to December 2015, 405 children with ALL were enrolled in this study. Peripheral blood was collected at the time of diagnosis, and lymphocyte subsets were detected by flow cytometry. Then, the percentages of lymphocyte subsets in each group were compared. In addition, survival and prognostic factor analyses were performed to determine the prognostic value of lymphocyte subsets. Lymphocyte subsets in children with ALL were dramatically different from those in healthy children and patients achieving CR. Additionally, lymphocyte subsets were correlated with different minimal residual disease and risk parameters. Furthermore, percentages of CD3+ T cells and CD4+ T cells and the ratio of CD4/CD8 were associated with different clinical outcomes. Multivariate analysis demonstrated the percentage of CD4+ T cell as an independent predictor for clinical prognosis. Lymphocyte subsets in pediatric ALL undergo dramatic changes and were related to prognosis, especially CD4+ T cells.

Anti-PD-L1 chimeric antigen receptor natural killer cell: Characterization and functional analysis

Like their natural counterparts, chimeric antigen receptor-engineered cells are prone to suppression by inhibitory signals, such as PD-L1, expressed by tumors or suppressor cells in the tumor microenvironment. Consequently, they become impaired, resulting in immune cell exhaustion, tumor progression, and resistance to other therapies. In this study, we developed an anti-PD-L1-CAR NK cell with efficient activity and a notable PD-L1-specific response toward tumor cell lines. The degranulation assay demonstrated that CD107a frequencies between the PD-L1med and PD-L1high groups and between Herceptin-treated and non-treated groups were not statistically different. Further investigation into NK cell characterization, considering different markers such as CD57, KIR2D, and CD25, revealed that the majority of the population are activated expanding NK cells. At the same time, immune checkpoint inhibitors, including PD-1, PD-L1, and LAG-3, showed increased levels following activation and expansion. Regarding the efficient functional activity of PD-L1-CAR NK cells and the instinctive receptor balance-based response of NK cells, this observation could point to the inhibition of NK cell overactivation or even higher cytotoxicity and cytokine production rather than exhaustion, especially in the case of healthy NK cells. These findings can contribute to a better understanding of the potential and challenges of using primary NK cells for CAR-NK cell therapy.

Paradoxical cell targeting of calreticulin-empowered, protein-only nanoparticles

Surface-exposed calreticulin (CRT) serves as a crucial cell damage-associated molecular pattern for immunogenic apoptosis, by generating an "eat me" signal to macrophages. Aiming at precision immunotherapies we intended to artificially label tumoral cells in vivo with a recombinant CRT, in a targeted way. For that, we have constructed a CRT fusion protein intended to surface attach CXCR4+ cancer cells, to stimulate their immunological destruction. As a targeting ligand of the CRT construct and to drive its specific cell adhesion, we used the peptide V1, a derivative of the vMIP-II cytokine and an antagonist of CXCR4. The modular protein tends to self-assemble as regular 16 nm nanoparticles, assisted by ionic Zn. Through both in vivo and in vitro experiments, we have determined that CRT itself confers cell targeting capabilities to the construct overcoming those of V1, that are only moderate. In particular, CRT binds HeLa cells in absence of further internalization, by a route fully independent of CXCR4. Furthermore, by cytometry in THP-1 cells, we observed that the binding of the protein is preferential for dead cells over live cells, a fact that cannot be associated to a mere artefactual adsorption. These data are discussed in the context of the oligomerizing properties of CRT and the potential clinical applicability of proteins and protein materials functionalized with this novel cell surface ligand.

Sijunzi decoction enhances sensitivity of colon cancer cells to NK cell destruction by modulating P53 expression

ETHNOPHARMACOLOGICAL RELEVANCE

Sijunzi Decoction (SJZD), a traditional Chinese herbal remedy, is frequently employed in the treatment of various cancers, including colon cancer. Previous research suggests that SJZD plays a pivotal role in modulating the immune system and enhancing immunity against tumors. However, the precise role of SJZD in combating colon cancer and its potential molecular functions in regulating natural killer cells remain elusive.

AIMS OF THE STUDY

To elucidate the potential mechanism underlying the anticolon cancer effects of SJZD in synergy with natural killer (NK) cells through both in vivo and in vitro experiments.

MATERIALS AND METHODS

In vivo experiments: A subcutaneous tumor mouse model of colon cancer and in vivo NK cell depletion experiments were conducted to observe the anticolon cancer effects of SJZD. Flow cytometry assessed immune cell depletion in mouse spleens, while immunohistochemical (IHC) staining detected the expression of apoptotic genes in tumor tissues. In vitro experiments: The mechanism by which SJZD regulates the sensitization of colon cancer cells to NK cells was investigated using real-time polymerase chain reaction (RT-PCR), western blotting (WB), and co-culture experiments with NK cells.

RESULTS

Sijunzi Decoction (SJZD) significantly impeded tumor growth in mice; however, NK cell depletion markedly attenuated the tumor-suppressive effect of SJZD. Immunohistochemical (IHC) results indicated that SJZD increased the expression of P53, death receptor 4 (DR4), and death receptor 5 (DR5) in tumor tissues. In vitro experiments, 24 h SJZD-pretreated colon cancer cells showed a substantial elevation in P53, DR4, and DR5 levels, and the activity of colon cancer cells significantly diminished after co-culture with NK cells. These effects of SJZD were reversed with the addition of the P53 inhibitor pifithrin-α (PFT-α), resulting in reduced inhibition of colon cancer cells by NK cells.

CONCLUSION

SJZD enhances the levels of DR4 and DR5 through the modulation of P53 expression, consequently increasing the sensitivity of colon cancer cells to NK cell-mediated killing. These findings provide a theoretical foundation for the clinical application of SJZD in patients with colon cancer. In this study, we first investigated the effect of SJZD on subcutaneous tumor growth in mice with colon cancer using in vivo assays and assessed the impact of NK cells on the anticolon cancer effect of SJZD in vivo through NK cell depletion. In vitro experiments were conducted to explore the potential mechanism of action of SJZD in NK cell-mediated anticolon cancer effects.

Hybrid epithelial-mesenchymal status of lung cancer dictates metastatic success through differential interaction with NK cells

BACKGROUND

Epithelial to mesenchymal transition (EMT) endows cancer cells with pro-metastatic properties, which appear most effective when cells enter an intermediate hybrid (H) state, characterized by integrated mesenchymal (M) and epithelial (E) traits. The reasons for this advantage are poorly known and, especially, it is totally unexplored whether the interplay between H-cells and NK cells could have a role. Here we characterize the pro-metastatic mechanics of non-small cell lung cancer (NSCLC) H-cells and their subset of cancer-initiating cells (CICs), dissecting crucial interactions with NK cells.

METHODS

Human lung cancer cell lines and sublines representative of E, M, or H states, assessed by proteomics, were analyzed in vivo for their tumor-forming and disseminating capabilities. Interactions with NK cells were investigated in vitro using migration assays, cytotoxic degranulation assays, and evaluation of CD133+ CICs modulation after coculture, and validated in vivo through NK cell neutralization assays. Correlation between EMT status, NK cell infiltration, and survival data, was evaluated in a cohort of surgically resected NSCLC cases (n=79).

RESULTS

We demonstrated that H-cells, have limited dissemination capability but show the highest potential to initiate metastases in vivo. This property was related to their ability to escape NK cell surveillance. Mechanistically, H-cells expressed low levels of NK-attracting chemokines (CXCL1 and CXCL8), generating poorly infiltrated metastases. Accordingly, proteomics and GO enrichment analysis of E, H, M cell lines showed that the related secretory processes could change during EMT.Furthermore, H-CICs uniquely expressed high levels of the inhibitory ligand B7-H3, which protected H-CIC from NK cell-mediated clearance. In vivo neutralization assays confirmed that, indeed, the pro-metastatic properties of H-cells are poorly controlled by NK cells.Finally, the analysis of patients revealed that detection of hybrid phenotypes associated with low NK infiltration in NSCLC clinical specimens could identify a subset of patients with poor prognosis.

CONCLUSIONS

Our study demonstrates that H-cells play a central role in the metastatic spread in NSCLC. Such pro-metastatic advantage of H-cells is supported by their altered interaction with NK cells and by the critical role of B7-H3 in preserving their H-CIC component, indicating B7-H3 as a potential target in combined NK-based therapies.

Metastasis Models: Thermodynamics and Complexity

The thermodynamic formalism of nonequilibrium systems together with the theory of complex systems and systems biology offer an appropriate theoretical framework to explain the complexity observed at the macroscopic level in physiological phenomena. In turn, they allow the establishment of an appropriate conceptual and operational framework to address the study of phenomena such as the emergence and evolution of cancer.This chapter is organized as follows: In Subheading 1, an integrated vision of these disciplines is offered for the characterization of the emergence and evolution of cancer, seen as a nonlinear dynamic system, temporally and spatially self-organized out of thermodynamic equilibrium. The development of the various mathematical models and different techniques and approaches used in the characterization of cancer metastasis is presented in Subheading 2. Subheading 3 is devoted to the time course of cancer metastasis, with particular emphasis on the epithelial-mesenchymal transition (EMT henceforth) as well as chronotherapeutic treatments. In Subheading 4, models of the spatial evolution of cancer metastasis are presented. Finally, in Subheading 5, some conclusions and remarks are presented.

Uncovering novel therapeutic targets in glucose, nucleotides and lipids metabolism during cancer and neurological diseases

BACKGROUND

Cell metabolism functions without a stop in normal and pathological cells. Different metabolic changes occur in the disease. Cell metabolism influences biochemical and metabolic processes, signaling pathways, and gene regulation. Knowledge regarding disease metabolism is limited.

OBJECTIVE

The review examines the cell metabolism of glucose, nucleotides, and lipids during homeostatic and pathological conditions of neurotoxicity, neuroimmunological disease, Parkinson's disease, thymoma in myasthenia gravis, and colorectal cancer.

METHODS

Data collection includes electronic databases, the National Center for Biotechnology Information, and Google Scholar, with several inclusion criteria: cell metabolism, glucose metabolism, nucleotide metabolism, and lipid metabolism in health and disease patients suffering from neurotoxicity, neuroinflammation, Parkinson's disease, thymoma in myasthenia gravis. The initial number of collected and analyzed papers is 250. The final analysis included 150 studies out of 94 selected papers. After the selection process, 62.67% remains useful.

RESULTS AND CONCLUSION

A literature search shows that signaling molecules are involved in metabolic changes in cells. Differences between cancer and neuroimmunological diseases are present in the result section. Our finding enables insight into novel therapeutic targets and the development of scientific approaches for cancer and neurological disease onset, outcome, progression, and treatment, highlighting the importance of metabolic dysregulation. Current understanding, emerging research technologies and potential therapeutic interventions in metabolic programming is disucussed and highlighted.

Cellular-Membrane-Derived Vesicles for Cancer Immunotherapy

The medical community is constantly searching for new and innovative ways to treat cancer, and cellular-membrane-derived artificial vesicles are emerging as a promising avenue for cancer immunotherapy. These vesicles, which are derived from mammal and bacteria cell membranes, offer a range of benefits, including compatibility with living organisms, minimal immune response, and prolonged circulation. By modifying their surface, manipulating their genes, combining them with other substances, stimulating them externally, and even enclosing drugs within them, cellular vesicles have the potential to be a powerful tool in fighting cancer. The ability to merge drugs with diverse compositions and functionalities in a localized area is particularly exciting, as it offers a way to combine different immunotherapy treatments for maximum impact. This review contains information on the various sources of these vesicles and discusses some recent developments in cancer immunotherapy using this promising technology. While there are still obstacles to overcome, the possibilities for cellular vesicles in cancer treatment are truly exciting.

CAR NK Cell Therapy for the Treatment of Metastatic Melanoma: Potential & Prospects

Melanoma is among the most lethal forms of cancer, accounting for 80% of deaths despite comprising just 5% of skin cancer cases. Treatment options remain limited due to the genetic and epigenetic mechanisms associated with melanoma heterogeneity that underlie the rapid development of secondary drug resistance. For this reason, the development of novel treatments remains paramount to the improvement of patient outcomes. Although the advent of chimeric antigen receptor-expressing T (CAR-T) cell immunotherapies has led to many clinical successes for hematological malignancies, these treatments are limited in their utility by their immune-induced side effects and a high risk of systemic toxicities. CAR natural killer (CAR-NK) cell immunotherapies are a particularly promising alternative to CAR-T cell immunotherapies, as they offer a more favorable safety profile and have the capacity for fine-tuned cytotoxic activity. In this review, the discussion of the prospects and potential of CAR-NK cell immunotherapies touches upon the clinical contexts of melanoma, the immunobiology of NK cells, the immunosuppressive barriers preventing endogenous immune cells from eliminating tumors, and the structure and design of chimeric antigen receptors, then finishes with a series of proposed design innovations that could improve the efficacy CAR-NK cell immunotherapies in future studies.

Advances in novel strategies for isolation, characterization, and analysis of CTCs and ctDNA

Over the past decade, the detection and analysis of liquid biopsy biomarkers such as circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) have advanced significantly. They have received recognition for their clinical usefulness in detecting cancer at an early stage, monitoring disease, and evaluating treatment response. The emergence of liquid biopsy has been a helpful development, as it offers a minimally invasive, rapid, real-time monitoring, and possible alternative to traditional tissue biopsies. In resource-limited settings, the ideal platform for liquid biopsy should not only extract more CTCs or ctDNA from a minimal sample volume but also accurately represent the molecular heterogeneity of the patient's disease. This review covers novel strategies and advancements in CTC and ctDNA-based liquid biopsy platforms, including microfluidic applications and comprehensive analysis of molecular complexity. We discuss these systems' operational principles and performance efficiencies, as well as future opportunities and challenges for their implementation in clinical settings. In addition, we emphasize the importance of integrated platforms that incorporate machine learning and artificial intelligence in accurate liquid biopsy detection systems, which can greatly improve cancer management and enable precision diagnostics.

mAb14, a Monoclonal Antibody against Cell Surface PCNA: A Potential Tool for Sezary Syndrome Diagnosis and Targeted Immunotherapy

Mycosis fungoides (MF) and Sézary syndrome (SS) are the most common types of primary cutaneous T-cell lymphoma (CTCL). Proliferating cell nuclear antigen (PCNA) is expressed on the cell surface of cancer cells (csPCNA), but not on normal cells. It functions as an immune checkpoint ligand by interacting with natural killer (NK) cells through the NK inhibitory receptor NKp44, leading to the inhibition of NK cytotoxicity. A monoclonal antibody (mAb14) was established to detect csPCNA on cancer cells and block their interaction with NKp44. In this study, three CTCL cell lines and peripheral blood mononuclear cells (PBMCs) from patients with SS and healthy donors were analyzed for csPCNA using mAb14, compared to monoclonal antibody PC10, against nuclear PCNA (nPCNA). The following assays were used: immunostaining, imaging flow cytometry, flow cytometry, cell sorting, cell cycle analysis, ELISA, and the NK-cell cytotoxic assay. mAb14 successfully detected PCNA on the membrane and in the cytoplasm of viable CTCL cell lines associated with the G2/M phase. In the Sézary PBMCs, csPCNA was expressed on lymphoma cells that had an atypical morphology and not on normal cells. Furthermore, it was not expressed on PBMCs from healthy donors. In the co-culture of peripheral blood NK (pNK) cells with CTCL lines, mAb14 increased the secretion of IFN-γ, indicating the reactivation of pNK activity. However, mAb14 did not enhance the cytotoxic activity of pNK cells against CTCL cell lines. The unique expression of csPCNA detected by mAb14 suggests that csPCNA and mAb14 may serve as a potential biomarker and tool, respectively, for detecting malignant cells in SS and possibly other CTCL variants.

Advancing Immunotherapies for HPV-Related Cancers: Exploring Novel Vaccine Strategies and the Influence of Tumor Microenvironment

The understanding of the relationship between immunological responses and cancers, especially those related to HPV, has allowed for the study and development of therapeutic vaccines against these neoplasias. There is a growing number of studies about the composition and influence of the tumor microenvironment (TME) in the progression or establishment of the most varied types of cancer. Hence, it has been possible to structure immunotherapy approaches based on therapeutic vaccines that are even more specific and directed to components of TME and the immune response associated with tumors. Among these components are dendritic cells (DCs), which are the main professional antigen-presenting cells (APCs) already studied in therapy strategies for HPV-related cancers. On the other hand, tumor-associated macrophages are also potential targets since the profile present in tumor infiltrates, M1 or M2, influences the prognosis of some types of cancer. These two cell types can be targets for therapy or immunomodulation. In this context, our review aims to provide an overview of immunotherapy strategies for HPV-positive tumors, such as cervical and head and neck cancers, pointing to TME immune cells as promising targets for these approaches. This review also explores the potential of immunotherapy in cancer treatment, including checkpoint inhibitors, cytokine immunotherapies, immunotherapy vaccines, and cell therapies. Furthermore, it highlights the importance of understanding the TME and its effect on the design and achievement of immunotherapeutic methods.

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

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

Radiation combined with ultrasound and microbubbles: A potential novel strategy for cancer treatment

Cancer is one of the leading causes of death worldwide. Several emerging technologies are helping to battle cancer. Cancer therapies have been effective at killing cancer cells, but a large portion of patients still die to this disease every year. As such, more aggressive treatments of primary cancers are employed and have been shown to be capable of saving a greater number of lives. Recent research advances the field of cancer therapy by employing the use of physical methods to alter tumor biology. It uses microbubbles to enhance radiation effect by damaging tumor vasculature followed by tumor cell death. The technique can specifically target tumor volumes by conforming ultrasound fields capable of microbubbles stimulation and localizing it to avoid vascular damage in surrounding tissues. Thus, this new application of ultrasound-stimulated microbubbles (USMB) can be utilized as a novel approach to cancer therapy by inducing vascular disruption resulting in tumor cell death. Using USMB alongside radiation has showed to augment the anti-vascular effect of radiation, resulting in enhanced tumor response. Recent work with nanobubbles has shown vascular permeation into intracellular space, extending the use of this new treatment method to potentially further improve the therapeutic effect of the ultrasound-based therapy. The significant enhancement of localized tumor cell kill means that radiation-based treatments can be made more potent with lower doses of radiation. This technique can manifest a greater impact on radiation oncology practice by increasing treatment effectiveness significantly while reducing normal tissue toxicity. This review article summarizes the past and recent advances in USMB enhancement of radiation treatments. The review mainly focuses on preclinical findings but also highlights some clinical findings that use USMB as a therapeutic modality in cancer therapy.

Slow Cooling and Controlled Ice Nucleation Enabling the Cryopreservation of Human T Lymphocytes with Low-Concentration Extracellular Trehalose

Cryopreservation of human T lymphocytes has become a key strategy for supporting cell-based immunotherapy. However, the effects of ice seeding on the cryopreservation of cells under relatively slow cooling have not been well researched. The cryopreservation strategy with a nontoxic, single-ingredient, and injectable cryoprotective solution remains to be developed. We conducted ice seeding for the cells in a solution of normal saline with 1% (v/v) dimethyl sulfoxide (Me2SO), 0.1 M trehalose, and 4% (w/v) human serum albumin (HSA) under different slow cooling rates. With the positive results, we further applied seeding in the solution of 0.2 M trehalose and 4% (w/v) HSA under the same cooling rates. The optimal concentration of trehalose in the Me2SO-free solutions was then investigated under the optimized cooling rate with seeding, with control groups without seeding, and in a freezing container. In vitro toxicity of the cryoprotective solutions to the cells was also tested. We found that the relative viability of cells (1% [v/v] Me2SO, 0.1 M trehalose and 4% [w/v] HSA) was improved significantly from 88.6% to 94.1% with ice seeding, compared with that without seeding (p < 0.05). The relative viability of cells (0.2 M trehalose and 4% [w/v] HSA) with seeding was significantly higher than that without seeding, 96.3% and 92.0%, respectively (p < 0.05). With no significant difference in relative viability between the solutions of 0.2 M trehalose or 0.3 M trehalose with 4% (w/v) HSA (92.4% and 94.6%, respectively, p > 0.05), the solution of 0.2 M trehalose and 4% (w/v) HSA was selected as the optimized Me2SO-free solution. This strategy could cryopreserve human T lymphocytes without any toxic cryoprotectant and boost the application of cell products in humans by intravenous injection, with the osmolality of the low-concentration cryoprotective solution close to that of human plasma.

Type 2 Dendritic Cells Orchestrate a Local Immune Circuit to Confer Antimetastatic Immunity

The progression of transformed primary tumors to metastatic colonization is a lethal determinant of disease outcome. Although circulating adaptive and innate lymphocyte effector responses are required for effective antimetastatic immunity, whether tissue-resident immune circuits confer initial immunity at sites of metastatic dissemination remains ill defined. Here we examine the nature of local immune cell responses during early metastatic seeding in the lung using intracardiac injection to mimic monodispersed metastatic spread. Using syngeneic murine melanoma and colon cancer models, we demonstrate that lung-resident conventional type 2 dendritic cells (DC2) orchestrate a local immune circuit to confer host antimetastatic immunity. Tissue-specific ablation of lung DC2, and not peripheral DC populations, led to increased metastatic burden in the presence of an intact T cell and NK cell compartment. We demonstrate that DC nucleic acid sensing and transcription factors IRF3 and IRF7 signaling are required for early metastatic control and that DC2 serve as a robust source of proinflammatory cytokines in the lung. Critically, DC2 direct the local production of IFN-γ by lung-resident NK cells, which limits the initial metastatic burden. Collectively, our results highlight, to our knowledge, a novel DC2-NK cell axis that colocalizes around pioneering metastatic cells to orchestrate an early innate immune response program to limit initial metastatic burden in the lung.

The Emerging Role of NK Cells in Immune Checkpoint Blockade

Natural killer (NK) cells are innate cytotoxic immune cells that play a fundamental role in anti-tumor immunity, particularly in hematological cancers, disseminated cancers, and metastasis [...].

HDAC7 inhibits cell proliferation via NudCD1/GGH axis in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most malignant subtype of breast cancer. In the absence of effective molecular markers for TNBC, there is an urgent clinical need for promising therapeutic target for TNBC. Histone deacetylases (HDACs), key regulators for chromatin remodeling and gene expression, have been suggested to play critical roles in cancer development. However, little is known ~the functions and implications of HDACs in TNBC treatment in the future. By analyzing the expression and prognostic significance of HDAC family members in TNBC through TCGA and METABRIC databases, HDAC7 was found to be downregulated in TNBC samples and the survival of patients with lower expression of HDAC7 was shorter. Furthermore, HDAC7 was negatively associated with NudC domain containing 1 (NudCD1) and γ-glutamyl hydrolase (GGH). Loss of NudCD1 or GGH predicted improved overall survival time (OS) of patients with TNBC. In vitro experiments showed that silencing of HDAC7 enhanced TNBC cell proliferation, while overexpression HDAC7 inhibited TNBC cell proliferation. The results of functional experiments confirmed that HDAC7 negatively modulated GGH and NudCD1 expression. Furthermore, decrease of NudCD1 or GGH inhibited cell proliferation. Notably, the HDAC7-NudCD1/GGH axis was found to be associated with NK cell infiltration. Overall, the present study revealed a novel role of HDAC7-NudCD1/GGH axis in TNBC, which might provide a promising treatment strategy for patients with TNBC.

Interdependence of sequential cytotoxic T lymphocyte and natural killer cell cytotoxicity against melanoma cells

Cytotoxic T lymphocytes (CTL) and natural killer (NK) cells recognize and eliminate cancer cells. However, immune evasion, downregulation of immune function by the tumour microenvironment and resistance of cancer cells are major problems. Although CTL and NK cells are both important to eliminate cancer, most studies address them individually. We quantified sequential primary human CTL and NK cell cytotoxicity against the melanoma cell line SK-Mel-5. At high effector-to-target ratios, NK cells or melan-A (MART-1)-specific CTL eliminated all SK-Mel-5 cells within 24 h, indicating that SK-Mel-5 cells are not resistant initially. However, at lower effector-to-target ratios, which resemble numbers of the immune contexture in human cancer, a substantial number of SK-Mel-5 cells survived. Pre-exposure to CTL induced resistance in surviving SK-Mel-5 cells to subsequent CTL or NK cell cytotoxicity, and pre-exposure to NK cells induced resistance in surviving SK-Mel-5 cells to NK cells. Higher human leucocyte antigen class I expression or interleukin-6 levels were correlated with resistance to NK cells, whereas reduction in MART-1 antigen expression was correlated with reduced CTL cytotoxicity. The CTL cytotoxicity was rescued beyond control levels by exogenous MART-1 antigen. In contrast to the other three combinations, CTL cytotoxicity against SK-Mel-5 cells was enhanced following NK cell pre-exposure. Our assay allows quantification of sequential CTL and NK cell cytotoxicity and might guide strategies for efficient CTL-NK cell anti-melanoma therapies. KEY POINTS: Cytotoxic T lymphocytes (CTL) and natural killer (NK) cells eliminate cancer cells. Both CTL and NK cells attack the same targets, but most studies address them individually. In a sequential cytotoxicity model, the interdependence of antigen-specific CTL and NK cell cytotoxicity against melanoma is quantified. High numbers of antigen-specific CTL and NK cells eliminate all melanoma cells. However, lower numbers induce resistance if secondary CTL or NK cell exposure follows initial CTL exposure or if secondary NK cell exposure follows initial NK cell exposure. On the contrary, if secondary CTL exposure follows initial NK cell exposure, cytotoxicity is enhanced. Alterations in human leucocyte antigen class I expression and interleukin-6 levels are correlated with resistance to NK cells, whereas a reduction in antigen expression is correlated with reduced CTL cytotoxicity; CTL cytotoxicity is rescued beyond control levels by exogenous antigen. This assay and the results on interdependencies will help us to understand and optimize immune therapies against cancer.

Harnessing NK Cells to Control Metastasis

In recent years, tumor immunotherapy has produced remarkable results in tumor treatment. Nevertheless, its effects are severely limited in patients with low or absent pre-existing T cell immunity. Accordingly, metastasis remains the major cause of tumor-associated death. On the other hand, natural killer (NK) cells have the unique ability to recognize and rapidly act against tumor cells and surveil tumor cell dissemination. The role of NK cells in metastasis prevention is undisputable as an increase in the number of these cells mostly leads to a favorable prognosis. Hence, it is reasonable to consider that successful metastasis involves evasion of NK-cell-mediated immunosurveillance. Therefore, harnessing NK cells to control metastasis is promising. Circulating tumor cells (CTCs) are the seeds for distant metastasis, and the number of CTCs detected in the blood of patients with tumor is associated with a worse prognosis, whereas NK cells can eliminate highly motile CTCs especially in the blood. Here, we review the role of NK cells during metastasis, particularly the specific interactions of NK cells with CTCs, which may provide essential clues on how to harness the power of NK cells against tumor metastasis. As a result, a new way to prevent or treat metastatic tumor may be developed.

Evaluating Antibody Pharmacokinetics as Prerequisite for Determining True Efficacy as Shown by Dual Targeting of PD-1 and CD96

One important prerequisite for developing a therapeutic monoclonal antibody is to evaluate its in vivo efficacy. We tested the therapeutic potential of an anti-CD96 antibody alone or in combination with an anti-PD-1 antibody in a mouse colon cancer model. Early anti-PD-1 treatment significantly decreased tumor growth and the combination with anti-CD96 further increased the therapeutic benefit, while anti-CD96 treatment alone had no effect. In late therapeutic settings, the treatment combination resulted in enhanced CD8⁺ T cell infiltration of tumors and an increased CD8/Treg ratio. Measured anti-PD-1 concentrations were as expected in animals treated with anti-PD-1 alone, but lower at later time points in animals receiving combination treatment. Moreover, anti-CD96 concentrations dropped dramatically after 10 days and were undetectable thereafter in most animals due to the occurrence of anti-drug antibodies that were increasing antibody clearance. Comparison of the anti-PD-1 concentrations with tumor growth showed that higher antibody concentrations in plasma correlated with better therapeutic efficacy. The therapeutic effect of anti-CD96 treatment could not be evaluated, because plasma concentrations were too low. Our findings strongly support the notion of measuring both plasma concentration and anti-drug antibody formation throughout in vivo studies, in order to interpret pharmacodynamic data correctly.

Circulating tumor cell-blood cell crosstalk: Biology and clinical relevance

Circulating tumor cells (CTCs) are the seeds of distant metastasis, and the number of CTCs detected in the blood of cancer patients is associated with a worse prognosis. CTCs face critical challenges for their survival in circulation, such as anoikis, shearing forces, and immune surveillance. Thus, understanding the mechanisms and interactions of CTCs within the blood microenvironment is crucial for better understanding of metastatic progression and the development of novel treatment strategies. CTCs interact with different hematopoietic cells, such as platelets, red blood cells, neutrophils, macrophages, natural killer (NK) cells, lymphocytes, endothelial cells, and cancer-associated fibroblasts, which can affect CTC survival in blood. This interaction may take place either via direct cell-cell contact or through secreted molecules. Here, we review interactions of CTCs with blood cells and discuss the potential clinical relevance of these interactions as biomarkers or as targets for anti-metastatic therapies.

ELK3 modulates the antitumor efficacy of natural killer cells against triple negative breast cancer by regulating mitochondrial dynamics

Background

Triple negative breast cancer (TNBC) is the most lethal subtype of breast cancer due to its aggressive behavior and frequent development of resistance to chemotherapy. Although natural killer (NK) cell-based immunotherapy is a promising strategy for overcoming barriers to cancer treatment, the therapeutic efficacy of NK cells against TNBC is below expectations. E26 transformation-specific transcription factor ELK3 (ELK3) is highly expressed in TNBCs and functions as a master regulator of the epithelial-mesenchymal transition.

Methods

Two representative human TNBC cell lines, MDA-MB231 and Hs578T, were exposed to ELK3-targeting shRNA or an ELK3-expressing plasmid to modulate ELK3 expression. The downstream target genes of ELK3 were identified using a combined approach comprising gene expression profiling and molecular analysis. The role of ELK3 in determining the immunosensitivity of TNBC to NK cells was investigated in terms of mitochondrial fission–fusion transition and reactive oxygen species concentration both in vitro and in vivo.

Results

ELK3-dependent mitochondrial fission–fusion status was linked to the mitochondrial superoxide concentration in TNBCs and was a main determinant of NK cell-mediated immune responses. We identified mitochondrial dynamics proteins of 51 (Mid51), a major mediator of mitochondrial fission, as a direct downstream target of ELK3 in TNBCs. Also, we demonstrated that expression of ELK3 correlated inversely with that of Mid51, and that the ELK3-Mid51 axis is associated directly with the status of mitochondrial dynamics. METABRIC analysis revealed that the ELK3-Mid51 axis has a direct effect on the immune score and survival of patients with TNBC.

Conclusions

Taken together, the data suggest that NK cell responses to TNBC are linked directly to ELK3 expression levels, shedding new light on strategies to improve the efficacy of NK cell-based immunotherapy of TNBC.

CAR T Cells Targeting Membrane-Bound Hsp70 on Tumor Cells Mimic Hsp70-Primed NK Cells

Strategies to boost anti-tumor immunity are urgently needed to treat therapy-resistant late-stage cancers, including colorectal cancers (CRCs). Cytokine stimulation and genetic modifications with chimeric antigen receptors (CAR) represent promising strategies to more specifically redirect anti-tumor activities of effector cells like natural killer (NK) and T cells. However, these approaches are critically dependent on tumor-specific antigens while circumventing the suppressive power of the solid tumor microenvironment and avoiding off-tumor toxicities. Previously, we have shown that the stress-inducible heat shock protein 70 (Hsp70) is frequently and specifically expressed on the cell surface of many different, highly aggressive tumors but not normal tissues. We could take advantage of tumors expressing Hsp70 on their membrane (‘mHsp70’) to attract and engage NK cells after in vitro stimulation with the 14-mer Hsp70 peptide TKDNNLLGRFELSG (TKD) plus low dose interleukin (IL)-2. However, a potential limitation of activated primary NK cells after adoptive transfer is their comparably short life span. T cells are typically long-lived but do not recognize mHsp70 on tumor cells, even after stimulation with TKD/IL-2. To combine the advantages of mHsp70-specificity with longevity, we constructed a CAR having specificity for mHsp70 and retrovirally transduced it into primary T cells. Co-culture of anti-Hsp70 CAR-transduced T cells with mHsp70-positive tumor cells stimulates their functional responsiveness. Herein, we demonstrated that human CRCs with a high mHsp70 expression similarly attract TKD/IL-2 stimulated NK cells and anti-Hsp70 CAR T cells, triggering the release of their lytic effector protein granzyme B (GrB) and the pro-inflammatory cytokine interferon (IFN)-γ, after 4 and 24 hours, respectively. In sum, stimulated NK cells and anti-Hsp70 CAR T cells demonstrated comparable anti-tumor effects, albeit with somewhat differing kinetics. These findings, together with the fact that mHsp70 is expressed on a large variety of different cancer entities, highlight the potential of TKD/IL-2 pre-stimulated NK, as well as anti-Hsp70 CAR T cells to provide a promising direction in the field of targeted, cell-based immunotherapies which can address significant unmet clinical needs in a wide range of cancer settings.

Tissue-Resident Innate Immune Cell-Based Therapy: A Cornerstone of Immunotherapy Strategies for Cancer Treatment

Cancer immunotherapy has led to impressive advances in cancer treatment. Unfortunately, in a high percentage of patients is difficult to consistently restore immune responses to eradicate established tumors. It is well accepted that adaptive immune cells, such as B lymphocytes, CD4⁺ helper T lymphocytes, and CD8⁺ cytotoxic T-lymphocytes (CTLs), are the most effective cells able to eliminate tumors. However, it has been recently reported that innate immune cells, including natural killer cells (NK), dendritic cells (DC), macrophages, myeloid-derived suppressor cells (MDSCs), and innate lymphoid cells (ILCs), represent important contributors to modulating the tumor microenvironment and shaping the adaptive tumor response. In fact, their role as a bridge to adaptive immunity, make them an attractive therapeutic target for cancer treatment. Here, we provide a comprehensive overview of the pleiotropic role of tissue-resident innate immune cells in different tumor contexts. In addition, we discuss how current and future therapeutic approaches targeting innate immune cells sustain the adaptive immune system in order to improve the efficacy of current tumor immunotherapies.

Metastasis prevention: targeting causes and roots

The spread of tumor cells from the primary focus, metastasis, is the main cause of cancer mortality. Therefore, anticancer therapy should be focused on the prevention of metastatic disease. Key targets can be conditions in the primary tumor that are favorable for the appearance of metastatic cells and the first steps of the metastatic cascade. Here, we discuss different approaches for targeting metastasis causes (hypoxia, metabolism changes, and tumor microenvironment) and roots (angiogenesis, epithelial-mesenchymal transition, migration, and invasion). Also, we emphasize the challenges of the existing approaches for metastasis prevention and suggest opportunities to overcome them. In conclusion, we highlight the importance of clinical evaluation of the agents showing antimetastatic effects in vivo, especially in patients with early-stage cancers, the identification of metastatic seeds, and the development of therapeutics for their eradication.

Assessing the Future of Solid Tumor Immunotherapy

With the advent of cancer immunotherapy, there has been a major improvement in patient’s quality of life and survival. The growth of cancer immunotherapy has dramatically changed our understanding of the basics of cancer biology and has altered the standards of care (surgery, radiotherapy, and chemotherapy) for patients. Cancer immunotherapy has generated significant excitement with the success of chimeric antigen receptor (CAR) T cell therapy in particular. Clinical results using CAR-T for hematological malignancies have led to the approval of four CD19-targeted and one B-cell maturation antigen (BCMA)-targeted cell therapy products by the US Food and Drug Administration (FDA). Also, immune checkpoint inhibitors such as antibodies against Programmed Cell Death-1 (PD-1), Programmed Cell Death Ligand-1 (PD-L1), and Cytotoxic T-Lymphocyte-Associated Antigen 4 (CTLA-4) have shown promising therapeutic outcomes and long-lasting clinical effect in several tumor types and patients who are refractory to other treatments. Despite these promising results, the success of cancer immunotherapy in solid tumors has been limited due to several barriers, which include immunosuppressive tumor microenvironment (TME), inefficient trafficking, and heterogeneity of tumor antigens. This is further compounded by the high intra-tumoral pressure of solid tumors, which presents an additional challenge to successfully delivering treatments to solid tumors. In this review, we will outline and propose specific approaches that may overcome these immunological and physical barriers to improve the outcomes in solid tumor patients receiving immunotherapies.

C3aR Signaling Inhibits NK-cell Infiltration into the Tumor Microenvironment in Mouse Models

Many solid tumors have low levels of cytotoxic CD56dim natural killer (NK) cells, suggesting that CD56dim NK-cell exclusion from the tumor microenvironment (TME) contributes to the decreased response rate of immunotherapy. Complement component 3a (C3a) is known for its tumor-promoting and immunosuppressive roles in solid tumors. Previous reports have implicated the involvement of the C3a receptor (C3aR) in immune cell trafficking into the TME. C3aR is predominantly expressed on the surface of activated cytotoxic NK cells, but a specific role for C3aR in NK-cell biology has not been investigated. Because solid tumors generate elevated C3a and have decreased NK-cell infiltration, we hypothesized that C3aR might play a role in cytotoxic NK-cell recruitment into the TME. Our results indicate that blocking C3aR signaling in NK cells increased NK-cell infiltration into the TME in mouse models and led to tumor regression. Because the critical lymphocyte trafficking integrin LFA-1 orchestrates the migration of activated NK cells, we wanted to gain insight into the interaction between C3aR signaling and LFA-1. Our results demonstrated that direct interaction between C3aR and LFA-1, which led to a high-affinity LFA-1 conformation, decreased NK-cell infiltration into the TME. We propose that approaches to enhance cytotoxic NK-cell infiltration into the TME, through either disrupting C3a and C3aR interaction or inhibiting the formation of high-affinity LFA-1, represent a new strategy to improve the efficiency of immunotherapy for cancer treatment.

Cross-Talk Between Tumor Cells Undergoing Epithelial to Mesenchymal Transition and Natural Killer Cells in Tumor Microenvironment in Colorectal Cancer

Tumor cells undergoing epithelial to mesenchymal transition (EMT) and immune cells in tumor microenvironment (TME) reciprocally influence each other. Immune cells, by supplying TME with bioactive molecules including cytokines, chemokines, enzymes, metabolites, and by physical interactions with tumor cells via their receptors, represent an important factor that affects EMT. Chronical inflammation in TME favorizes tumor growth and invasiveness and stimulates synthesis of EMT promoting transcription factors. Natural killer (NK) cells, owing to their unique ability to exert cytotoxic function independent of major histocompatibility (MHC)-mediated antigen presentation, play a significant role in the control of metastasis in colorectal cancer (CRC). Although, the cross-talk between immune cells and tumor cells in general favors the induction of EMT and inhibition of antitumor immune responses, there are some changes in the immunogenicity of tumor cells during EMT of CRC cells that increase their susceptibility to NK cell cytotoxic lysis. However, suppressive TME downmodulates the expression of activating NK cell receptors, decreases the expression of activating and increases the expression of inhibitory NK cell ligands on tumor cells, and impairs NK cell metabolism that altogether negatively affects the overall NK cell function. Furthermore, process of EMT is often associated with increased expression of programmed cell death ligand (PD-L) and expression of immune checkpoint molecules PD-1, TIGIT, and TIM3 on functionally exhausted NK cells in TME in CRC. In this review we discuss modalities of cross-talk between tumor cells and NK cells, with regard of EMT-driven changes.

Nanotechnology-enhanced immunotherapy for metastatic cancer

A vast majority of cancer deaths occur as a result of metastasis. Unfortunately, effective treatments for metastases are currently lacking due to the difficulty of selectively targeting these small, delocalized tumors distributed across a variety of organs. However, nanotechnology holds tremendous promise for improving immunotherapeutic outcomes in patients with metastatic cancer. In contrast to conventional cancer immunotherapies, rationally designed nanomaterials can trigger specific tumoricidal effects, thereby improving immune cell access to major sites of metastasis such as bone, lungs, and lymph nodes, optimizing antigen presentation, and inducing a persistent immune response. This paper reviews the cutting-edge trends in nano-immunoengineering for metastatic cancers with an emphasis on different nano-immunotherapeutic strategies. Specifically, it discusses directly reversing the immunological status of the primary tumor, harnessing the potential of peripheral immune cells, preventing the formation of a pre-metastatic niche, and inhibiting the tumor recurrence through postoperative immunotherapy. Finally, we describe the challenges facing the integration of nanoscale immunomodulators and provide a forward-looking perspective on the innovative nanotechnology-based tools that may ultimately prove effective at eradicating metastatic diseases.

Cell Membrane-Coated Mimics: A Methodological Approach for Fabrication, Characterization for Therapeutic Applications, and Challenges for Clinical Translation

Cell membrane-coated (CMC) mimics are micro/nanosystems that combine an isolated cell membrane and a template of choice to mimic the functions of a cell. The design exploits its physicochemical and biological properties for therapeutic applications. The mimics demonstrate excellent biological compatibility, enhanced biointerfacing capabilities, physical, chemical, and biological tunability, ability to retain cellular properties, immune escape, prolonged circulation time, and protect the encapsulated drug from degradation and active targeting. These properties and the ease of adapting them for personalized clinical medicine have generated a significant research interest over the past decade. This review presents a detailed overview of the recent advances in the development of cell membrane-coated (CMC) mimics. The primary focus is to collate and discuss components, fabrication methodologies, and the significance of physiochemical and biological characterization techniques for validating a CMC mimic. We present a critical analysis of the two main components of CMC mimics: the template and the cell membrane and mapped their use in therapeutic scenarios. In addition, we have emphasized on the challenges associated with CMC mimics in their clinical translation. Overall, this review is an up to date toolbox that researchers can benefit from while designing and characterizing CMC mimics.

Key Activating and Inhibitory Ligands Involved in the Mobilization of Natural Killer Cells for Cancer Immunotherapies

Natural killer (NK) cells are the most potent arm of the innate immune system and play an important role in immunity, alloimmunity, autoimmunity, and cancer. NK cells recognize “altered-self” cells due to oncogenic transformation or stress due to viral infection and target to kill them. The effector functions of NK cells depend on the interaction of the activating and inhibitory receptors on their surface with their cognate ligand expressed on the target cells. These activating and inhibitory receptors interact with major histocompatibility complex I (MHC I) expressed on the target cells and make decisions to mount an immune response. NK cell immune response includes cytolytic activity and secretion of cytokines to help with the ongoing immune response. The advancement of our knowledge on the expression of inhibitory and activating molecules led us to exploit these molecules in the treatment of cancer. This review discusses the importance of activating and inhibitory receptors on NK cells and their clinical importance in cancer immunotherapy.

Platelet-mediated tumor metastasis mechanism and the role of cell adhesion molecules

Mounting evidence suggests that platelets play an essential role in cancer metastasis. The interactions between platelets and circulating tumor cells (CTCs) promote cancer metastasis. CTCs induce platelet activation and aggregation, and activated platelets gather and protect CTCs from shear stress and natural killer cells. Finally, platelets stimulate CTC anoikis resistance, epithelial-to-mesenchymal transition, angiogenesis, extravasation, and eventually, metastasis. Cell adhesion molecules (CAMs) have been identified as active players during the interaction of CTCs with platelets, but the specific mechanism underlying the contribution of platelet-associated CAMs to CTC metastasis remains unclear. In this review, we introduce the mechanism of platelet-related tumor metastasis and particularly focus on the role of CAMs in it.

Purification and Conformational Characterization of a Novel Interleukin-2 Mutein

Toxicity of high-dose IL-2-based therapies have motivated the development of the IL-2 mutein, which has low expansion properties for regulatory T lymphocytes. The development of two variants (A and B) for the IL-2 mutein purification as well as a conformational comparative study by Circular dichroism (CD) and fluorescence spectroscopy of these products were evaluated. For the first time, in our center, were used of DTT and 2% SDS in the solubilization step to decrease the aggregates on intermediate product, which favors that disulfide bridges are correctly formed during re-folding. A molecular weight of 18 kDa to the monomeric form and of 25-37 kDa to the oligomeric species were estimated by SDS-PAGE. IL-2 mutein showed similar far-UV CD spectral characteristic typical of cytokines with 41% of α-helix content. Batches obtained by Process B showed similar conformational features according near-UV CD and FS studies. However, those obtained by Process A differed in their folding. IL-2 mutein showed that conformational features by near-UV CD were affected by 2% SDS, no variations on secondary structure were observed. Melting temperature values by far-UV CD were higher than 95 °C, indicating a high thermal stability. Finally, the drug product obtained by Process B showed similar conformational characteristics by near-UV CD and FS, and higher biological activity values (7.0 × 10³ ng/mL) in the cell proliferation assay with respect to Process A. Also, the recovery was 15% higher than in the Process A and exhibited a 78.48% of purity. Indeed, Process B was selected for the purification.

TIMP1 and TIMP2 Downregulate TGFβ Induced Decidual-like Phenotype in Natural Killer Cells

Simple Summary

Cancer patients are characterized by NK cells with altered surface markers, such as CD56 brightness, CD9, CD49a (pro-angiogenic) and PD-1, and TIM-3 (exhaustion), that favor immune escape. Transforming growth factor-beta (TGFβ) is a major tumor-derived cytokine that favors cancer growth and supports pro-angiogenic activities in NK cells by inducing pro-angiogenic molecules. TIMP-1 and TIMP-2 play a crucial role in extracellular matrix (ECM) regulation, wound healing, pregnancy and cancer, and there is increasing evidence that they are immune-modulatory. We found that recombinant TIMP-1 and -2 can partially contrast the induction of pro-tumor/pro-angiogenic decidual-like polarization of NK cells by TGFβ.

Abstract

Natural Killer (NK) cells have been found to be anergic, exhausted and pro-angiogenic in cancers. NK cell from healthy donors, exposed to TGFβ, acquire the CD56^brightCD9⁺CD49a⁺ decidual-like-phenotype, together with decreased levels of NKG2D activation marker, increased levels of TIM-3 exhaustion marker, similar to cancer-associated NK cells. Tissue inhibitors of metalloproteases (TIMPs) exert dual roles in cancer. The role of TIMPs in modulating immune cells is a very novel concept, and the present is the first report studying their ability to contrast TGFβ action on NK cells. Here, we investigated the effects of TIMP1 and TIMP2 recombinant proteins in hindering decidual-like markers in NK cells, generated by polarizing cytolytic NK cells with TGFβ. The effects of TIMP1 or TIMP2 on NK cell surface antigens were determined by multicolor flow cytometry. We found that TIMP1 and TIMP2 were effective in interfering with TGFβ induced NK cell polarization towards a decidual-like-phenotype. TIMP1 and TIMP2 counteracted the effect of TGFβ in increasing the percentage of CD56^bright, CD16⁻, CD9⁺ and CD49a⁺, and restoring normal levels for TIMP 1 and 2 also inhibited decrease levels of the activation marker NKG2D induced by TGFβ and decreased the TGFβ upregulated exhaustion marker TIM-3. NK cell degranulation capabilities against K562 cells were also decreased by TGFβ and not by TIMP1 or TIMP2. TIMP1 treatment could partially restore degranulation marker CD107a expression. Treatment with recombinant TIMP-1 or TIMP-2 showed a trend, although not statistically significant, to decrease CD49a⁺ and TIM-3+ expression and increase NKG2D in peripheral blood NK cells exposed to conditioned media from colon cancer cell lines. Our results suggest a potential role of TIMPs in controlling the tumor-associated cytokine TGFβ-induced NK cell polarization. Given the heterogeneity of released factors within the TME, it is clear that TGFβ stimulation represents a model to prove TIMP’s new properties, but it cannot be envisaged as a soloist NK cell polarizing agent. Therefore, further studies from the scientific community will help defining TIMPs immunomodulatory activities of NK cells in cancer, and their possible future diagnostic–therapeutic roles.

Temperature-Feedback Nanoplatform for NIR-II Penta-Modal Imaging-Guided Synergistic Photothermal Therapy and CAR-NK Immunotherapy of Lung Cancer

In this study, to visually acquire all-round structural and functional information of lung cancer while performing synergistic photothermal therapy (PTT) and tumor-targeting immunotherapy, a theranostic nanoplatform that introduced upconversion nanoparticles (UCNPs) and IR-1048 dye into the lipid-aptamer nanostructrure (UCILA) is constructed. Interestingly, the IR-1048 dye grafted into the lipid bilayer can serve as the theranostic agent for photoacoustic imaging, optical coherence tomography angiography, photothermal imaging, and PTT in the second near infrared (NIR-II) window. In addition, loaded in the inner part of UCILA, UCNPs possess the superior luminescence property and high X-ray attenuation coefficient, which can act as contrast agents for computed tomography (CT) and thermo-sensitive up-conversion luminescence (UCL) imaging, enabling real-time tracking of metabolic activity of tumor and temperature-feedback PTT. Furthermore, under the complementary guidance of penta-modal imaging and an accurate monitoring of in situ temperature change during PTT, UCILA exhibits its excellent capability for ablating the lung tumor with minimal side effects. Meanwhile, synergistic CAR-NK immunotherapy is carried out specifically to eradicate any possible residual tumor cells after PTT. Therefore, the UCILA nanoplatform is demonstrated as a multifunctional theranostic agent for both penta-modal imaging and temperature-feedback PTT while conducting targeting immunotherapy of lung cancer.

Modulation of the tumor microenvironment (TME) by melatonin

The tumor microenvironment (TME) includes a number of non-cancerous cells that affect cancer cell survival. Although CD8+ T lymphocytes and natural killer (NK) cells suppress tumor growth through induction of cell death in cancer cells, there are various immunosuppressive cells such as regulatory T cells (Tregs), tumor-associated macrophages (TAMs), cancer-associated fibroblasts (CAFs), myeloid-derived suppressor cells (MDSCs), etc., which drive cancer cell proliferation. These cells may also support tumor growth and metastasis by stimulating angiogenesis, epithelial-mesenchymal transition (EMT), and resistance to apoptosis. Interactions between cancer cells and other cells, as well as molecules released into EMT, play a key role in tumor growth and suppression of antitumoral immunity. Melatonin is a natural hormone that may be found in certain foods and is also available as a drug. Melatonin has been demonstrated to modulate cell activity and the release of cytokines and growth factors in TME. The purpose of this review is to explain the cellular and molecular mechanisms of cancer cell resistance as a result of interactions with TME. Next, we explain how melatonin affects cells and interactions within the TME.

Iron oxide nanoparticles for immune cell labeling and cancer immunotherapy

Cancer immunotherapy is a novel approach to cancer treatment that leverages components of the immune system as opposed to chemotherapeutics or radiation. Cell migration is an integral process in a therapeutic immune response, and the ability to track and image the migration of immune cells in vivo allows for better characterization of the disease and monitoring of the therapeutic outcomes. Iron oxide nanoparticles (IONPs) are promising candidates for use in immunotherapy as they are biocompatible, have flexible surface chemistry, and display magnetic properties that may be used in contrast-enhanced magnetic resonance imaging (MRI). In this review, advances in application of IONPs in cell tracking and cancer immunotherapy are presented. Following a brief overview of the cancer immunity cycle, developments in labeling and tracking various immune cells using IONPs are highlighted. We also discuss factors that influence the effectiveness of IONPs as MRI contrast agents. Finally, we outline different approaches for cancer immunotherapy and highlight current efforts that utilize IONPs to stimulate immune cells to enhance their activity and response to cancer.

High-grade serous ovarian tumor cells modulate NK cell function to create an immune-tolerant microenvironment

Tubo-ovarian high-grade serous carcinoma (HGSC) is unresponsive to immune checkpoint blockade despite significant frequencies of exhausted T cells. Here we apply mass cytometry and uncover decidual-like natural killer (dl-NK) cell subpopulations (CD56+CD9+CXCR3+KIR+CD3-CD16-) in newly diagnosed HGSC samples that correlate with both tumor and transitioning epithelial-mesenchymal cell abundance. We show different combinatorial expression patterns of ligands for activating and inhibitory NK receptors within three HGSC tumor compartments: epithelial (E), transitioning epithelial-mesenchymal (EV), and mesenchymal (vimentin expressing [V]), with a more inhibitory ligand phenotype in V cells. In cocultures, NK-92 natural killer cells acquire CD9 from HGSC tumor cells by trogocytosis, resulting in reduced anti-tumor cytokine production and cytotoxicity. Cytotoxicity in these cocultures is restored with a CD9-blocking antibody or CD9 CRISPR knockout, thereby identifying mechanisms of immune suppression in HGSC. CD9 is widely expressed in HGSC tumors and so represents an important new therapeutic target with immediate relevance for NK immunotherapy.

The Role of Natural Killer Cells in Soft Tissue Sarcoma: Prospects for Immunotherapy

Simple Summary

Soft-tissue sarcomas (STS) represent about 80% of sarcomas, and are a heterogeneous group of rare and malignant tumors. Morphological evaluation has been the standard model for the diagnosis of sarcomas, and even in samples with similar characteristics, they present genetic differences, which further increases the diversity of sarcomas. This variety is one of the main challenges for the classification and understanding of STS patterns, as well as for the respective treatments, which further decreases patient survival (<5 years). Natural Killer (NK) cells have a fundamental role in the control and immune surveillance of cancer development, progression and metastases. Notwithstanding the scarcity of studies to characterize NK cells in STS, it is noteworthy that the progression of these malignancies is associated with altered NK cells. These findings support the additional need to explore NK cell-based immunotherapy in STS; some clinical trials, although very tentatively, are already underway.

Abstract

Soft-tissue sarcomas (STS) represent about 80% of sarcomas, and are a heterogeneous group of rare and malignant tumors. STS arise from mesenchymal tissues and can grow into structures such as adipose tissue, muscles, nervous tissue and blood vessels. Morphological evaluation has been the standard model for the diagnosis of sarcomas, and even in samples with similar characteristics, they present a diversity in cytogenetic and genetic sequence alterations, which further increases the diversity of sarcomas. This variety is one of the main challenges for the classification and understanding of STS patterns, as well as for their respective treatments, which further decreases patient survival (<5 years). Despite some studies, little is known about the immunological profile of STS. As for the immunological profile of STS in relation to NK cells, there is also a shortage of studies. Observations made in solid tumors show that the infiltration of NK cells in tumors is associated with a good prognosis of the disease. Notwithstanding the scarcity of studies to characterize NK cells, their receptors, and ligands in STS, it is noteworthy that the progression of these malignancies is associated with altered NK phenotypes. Despite the scarcity of information on the function of NK cells, their phenotypes and their regulatory pathways in STS, the findings of this study support the additional need to explore NK cell-based immunotherapy in STS further. Some clinical trials, very tentatively, are already underway. STS clinical trials are still the basis for adoptive NK-cell and cytokine-based therapy.

Natural Killer Cells in Cancer and Cancer Immunotherapy

The detection and killing of neoplastic cells require coordination of a variety of antitumor effector cells. Natural killer (NK) cells of the innate immune system are at the forefront of the body's defense systems and evidence suggests that the infiltration and cytotoxicity of NK cells in the cancer tissue influence treatment efficacy and survival. As powerful effectors in the anticancer immune response, NK cells rapidly recognize and kill transformed cells with little reactivity against healthy self-tissues, which highlights their potential role in cancer immunotherapy. Modern immunotherapeutic approaches include immune checkpoint inhibitors to revitalize dysfunctional T cells and adoptive cell transfer using CD8⁺ T cells with chimeric antigen receptors to enhance their functionality. However, treatment responses may be short-lived and risk of discontinuation due to adverse effects necessitates the development of safer immuno-oncologic therapies with improved outcomes. To this end, novel combinatorial interventions using T cells and NK cells and strategies for overcoming associated challenges are currently being investigated. This review summarizes the advances in the research on NK cells in cancer and cancer immunotherapy and discusses the possible implications for future cancer treatment.

Immune Circuits to Shape Natural Killer Cells in Cancer

Simple Summary

Natural killer (NK) cells are circulating innate lymphocytes endowed with antitumoral functions. NK cells are the innate counterpart of effector T cells and among the first cells responding to infections and tumors. In this review, the immune circuits regulating the NK cell antitumoral functions and the possible strategies to shape natural killing in cancer will be discussed.

Abstract

Natural killer (NK) cells are innate lymphoid cells playing an important role in anti-cancer immunity. NK cells are efficient in controlling the spreading of metastasis but are not very powerful in fighting against primary tumors. The NK cell capability to infiltrate and persist in the tumor microenvironment and to exert their antitumoral functions is often limited by tumor escape mechanisms. These tumor-mediated strategies not only induce NK cell tolerance but also interfere with the NK cell-dependent immune networking. This review will provide an overview of the tumor escape mechanisms impacting NK cells, identify the immune circuits regulating the NK cell-dependent antitumor immunity and revise the emerging therapeutic approaches to unleash NK cells in cancer.

Tumor infiltrating NK cell (TINK) subsets and functional molecules in patients with breast cancer

INTRODUCTION

NK cells have been introduced as the main innate arm of immunity against malignancies. Recent advances introduced new subsets of, and new effector molecules on NK cells suggesting new paradigms for NK cell functions in tumor immunity. Considering these new paradigms, in the current research we investigated the frequency of tumor infiltrating NK cell (TINK) subsets and their functional molecules in breast tumor tissues by flowcytometry method.

METHODS

Breast tumor tissues were obtained from 32 untreated patients with breast cancer. The tissues were then minced mechanically to acquire a single cell suspension and surface-stained with monoclonal antibodies against CD3, CD56, CD11b, CD27, NKG2A, NKG2D and CXCR3. For intracellular staining (ICS), the surface-stained cells were then fixed, permeabilized and stained with anti-Perforin and anti-Granzyme B antibodies. The samples were run and the data were acquired on a four-color flowcytometer.

RESULTS

The cell suspension derived from tumor tissue encompassed 3.10 ± 0.52 % CD3^-CD56^{+(bright/dim)} total NK cells. Based on the conventional classification the percentages of cytotoxic (CD3^- CD56^dim) and regulatory (CD3^- CD56^bright) NK cells were respectively 1.74 ± 0.24 % and 1.36 ± 0.48 %. According to the new classification the percentages of cytotoxic (CD3- CD56⁺ CD11b⁺ CD27^-), regulatory (CD3^-CD56⁺ CD11b^+/- CD27⁺) and tolerant (CD3^-CD56⁺ CD27- CD11b^-) NK cells were respectively 0.48 ± 0.07, 1.55 ± 0.34 and 1.15 ± 0.51. A significant higher frequency of total NK cells (CD3^-CD56^{+ (bright/dim)}) in the breast tumor tissues of the patients whose tumor draining lymph nodes (TDLNs) has not been yet involved by tumor cells (LN^- patients) compared with the ones with lymph nodes involvement (LN⁺) (5.91 ± 1.79 % Vs. 2.20 ± 0.20 %, P < 0.004). Furthermore, NK cells with overexpressed activating receptor; NKGD2 (CD3- CD56^{+(bright/dim)} NKG2D⁺ NK cells) was observed to be elevated in LN^- patients compared with the LN⁺ ones (70.01 ± 7.96 Vs. 42.5 ± 4.81, P < 0.011). Correlation analysis revealed the percentages of conventional regulatory NK cells (CD3- CD56^bright) in breast tumor tissue to be in positive correlation with the tumor size (R = 0.380, P < 0.04). The mean percentage of this cell subset was also observed to be higher in patients with T3 tumor size compared with smaller T1 tumor size (1.61 ± 0.20 % vs. 0.75 ± 0.15 %, P < 0.023.

CONCLUSION

Our observations suggest that accumulation of NK cells as well as the expression of activating NKG2D receptor by TINKs may play roles in breast tumor regression especially in the LN^- patients. As the tumor growths and the size of tumor increases the accumulation of regulatory NK cells may facilitate the tumor improvement. These observations may have implications in cancer NK cell-based immunotherapy.

Stresses in the metastatic cascade: molecular mechanisms and therapeutic opportunities

In this review, Shen and Kang provide an overview of the tumor-intrinsic and microenvironment- and treatment-induced stresses that tumor cells encounter in the metastatic cascade and the molecular pathways they develop to relieve these stresses.

Metastasis is the ultimate “survival of the fittest” test for cancer cells, as only a small fraction of disseminated tumor cells can overcome the numerous hurdles they encounter during the transition from the site of origin to a distinctly different distant organ in the face of immune and therapeutic attacks and various other stresses. During cancer progression, tumor cells develop a variety of mechanisms to cope with the stresses they encounter, and acquire the ability to form metastases. Restraining these stress-releasing pathways could serve as potentially effective strategies to prevent or reduce metastasis and improve the survival of cancer patients. Here, we provide an overview of the tumor-intrinsic, microenvironment- and treatment-induced stresses that tumor cells encounter in the metastatic cascade and the molecular pathways they develop to relieve these stresses. We also summarize the preclinical and clinical studies that evaluate the potential therapeutic benefit of targeting these stress-relieving pathways.

LAG-3 Blockade with Relatlimab (BMS-986016) Restores Anti-Leukemic Responses in Chronic Lymphocytic Leukemia

The inclusion of monoclonal antibodies targeting immune checkpoints such PD-1/PD-L1 or CTLA-4 has revolutionized the landscape of anti-cancer therapy. However, PD-1 and CTLA-4 blockade failed to achieve clinical benefit in CLL, thus attention has been focused on emerging checkpoints in this malignancy. LAG-3 is an immune checkpoint receptor that negatively regulates T cell-mediated responses by inducing an hyporesponsive state, thus promoting tumor escape. Patients with chronic lymphocytic leukemia (CLL) develop a profound immune suppression that leads to lessened immunosurveillance and increased risk of developing a secondary neoplasia. In the study herein, we report the profound dysregulation of LAG-3 on leukemic cells in CLL. Likewise, natural killer (NK) and T cells showed increased LAG-3 expression, hence suggesting a role for this checkpoint in CLL-associated immunosuppression. High LAG-3 expression, as well as high levels of soluble LAG-3 (sLAG-3), correlated with adverse cytogenetics and poor outcome in patients with CLL, highlighting the clinical relevance of this immune checkpoint. Treatment of peripheral blood mononuclear cells (PBMCs) from patients with CLL with relatlimab, a new anti-LAG-3 blocking antibody currently evaluated in numerous clinical trials, depleted leukemic cells and restored NK cell- and T cell-mediated responses. Moreover, combination of LAG-3 with the immunomodulatory drug (IMiD) lenalidomide significantly increased IL-2 production by T cells and antibody-dependent cytotoxicity (ADCC) mediated by NK cells. Altogether, these data provide new insights into the potential anti-leukemic effects of relatlimab, currently in clinical trials in CLL, and provides the rationale to further investigate its combination with IMiDs for the management of hematological malignancies.