Myeloid-Derived Suppressor Cells as a Therapeutic Target for Cancer

Advances in research on flavonoids in tumor immunotherapy (Review)

Cancer immunotherapy is an approach used in anti‑tumor treatment; however, its efficacy is limited to specific tumor types that are inherently sensitive to immune system modulation. Expanding the scope of indications and enhancing the efficacy of cancer immunotherapy are key goals for continued advancement. Flavonoids modulate the tumor‑immunosuppressive microenvironment. Integrating flavonoids with immunotherapeutic modalities, including cancer vaccines, immune checkpoint inhibitors and adoptive immune‑cell therapy, has potential in terms of augmenting the therapeutic efficacy of immunotherapy. The present review aimed to summarize flavonoids that enhance cancer immunotherapy, focusing on their underlying mechanisms and the application of nanotechnology to overcome inherent limitations such as poor solubility, low bioavailability, rapid metabolism, and instability under physiological conditions, thereby highlighting the potential of flavonoids in advancing cancer immunotherapy.

Glucocorticoid Receptor-Targeted Nanoliposome for STAT3 Inhibition-Led Myeloid-Derived Suppressor Cell Modulation and Efficient Colon Cancer Treatment

STAT3 is an important protein responsible for cellular proliferation, motility, and immune tolerance and is hyperactive in colorectal cancer, instigating metastasis, cellular proliferation, migration, as well as inhibition. It helps in proliferation of myeloid-derived suppressor cells (MDSCs), which within the tumor microenvironment (TME) suppress T cells to encourage tumor growth, metastasis, and resistance to immunotherapy, besides playing dynamic role in regulating macrophages within the tumor. Thus, MDSC is a potential target to augment immune surveillance within the TME. Herein, we report targeting both colorectal cancer and MDSCs using a glucocorticoid receptor (GR)-targeted nanoliposomal formulation carrying GR-ligand, dexamethasone (Dex), and a STAT3 inhibitor, niclosamide (N). Our main objective was to selectively inhibit STAT3, the key immunomodulatory factor in most TME-associated cells including MDSCs, and also repurpose the use of this antihelminthic, low-cost drug N for cancer treatment. The resultant formulation D1XN exhibited better tumor regression and survivability compared to GR nontargeted formulation. Further, bone marrow cell-derived MDSCs were engineered by D1XN treatment ex vivo and were inoculated back to tumor-bearing mice. Significant tumor growth inhibition with enhanced antiproliferative immune cell signatures, such as T cell infiltration, decrease in Treg cells, and increased M1/M2 macrophage ratio within the TME were observed. This reveals the effectiveness of engineered MDSCs to modulate tumor surveillance besides reversing the aggressiveness of the tumor. Therefore, D1XN and D1XN-mediated engineered MDSCs alone or in combination can be considered as potent selective chemo-immunotherapeutic nanoliposomal agent(s) against colorectal cancer.

Contemporary understanding of myeloid-derived suppressor cells in the acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) tumor microenvironment

INTRODUCTION

Myeloid-derived suppressor cells (MDSCs) are a key immunosuppressive component in the tumor microenvironment, contributing to immune evasion and disease progression in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS).

AREAS COVERED

We searched PubMed for literature that evaluated the effect of MDSCs in myeloid diseases. MDSCs impact outcomes by facilitating leukemic stem cell survival, impairing immune checkpoint efficacy, and modulating the bone marrow niche. While these immunosuppressive properties can mitigate graft-versus-host disease post-transplantation, sustained MDSC-mediated immunosuppression can also increase the risk of leukemia relapse.We review MDSC development and function, including metabolic reprogramming, epigenetic modifications, and cytokine-mediated pathways. Therapeutic strategies targeting MDSCs, such as depletion, functional reprogramming, and inhibition of key metabolic and immune pathways, show promising data in preclinical models. However, clinical translation remains hindered by challenges in MDSC quantification and standardization of functional assays. This review underscores the potential of combining MDSC-targeted therapies with conventional and novel treatments to improve patient outcomes in AML and MDS.

EXPERT OPINION

Future studies should focus on standardizing MDSC assessment, elucidate their dynamic roles in therapy, and optimize combination approaches for clinical application.

The immunosuppressive role of MDSCs in HCC: mechanisms and therapeutic opportunities

Hepatocellular carcinoma (HCC) is a prevalent malignancy with a significant global burden. Despite substantial advancements in HCC treatment in recent years, therapeutic efficacy remains constrained by immune evasion mechanisms within the tumor microenvironment (TME). Myeloid-derived suppressor cells (MDSCs), as critical immunosuppressive elements of the TME, have garnered increasing attention for their role in tumor progression. Recent studies emphasize their central involvement in promoting immune evasion, tolerance, and immunosuppression in HCC. This review examines the contributions of MDSCs to HCC pathogenesis, elucidates their underlying mechanisms, and discusses ongoing clinical trials, emphasizing their potential as therapeutic targets for improving clinical outcomes.

Targeting the disrupted Hippo signaling to prevent neoplastic renal epithelial cell immune evasion

Large-scale cancer genetic/genomic studies demonstrated that papillary renal cell carcinoma (pRCC) is featured with a frequent shallow deletion of the upstream tumor suppressors of the Hippo/YAP signaling pathway, suggesting that this signaling pathway may play a role in pRCC development. Here we develop a transgenic mouse model with a renal epithelial cell-specific hyperactivation of YAP1 and find that hyperactivation of YAP1 can induce dedifferentiation and transformation of renal tubular epithelial cells leading to the development of pRCC. We analyze at the single-cell resolution the cellular landscape alterations during cancer initiation and progression. Our data indicate that the hyperactivated YAP1, via manipulating multiple signaling pathways, induces epithelial cell transformation, MDSC (Myeloid-derived suppressor cells) accumulation, and pRCC development. Interestingly, we find that depletion of MDSC blocks YAP1-induced kidney overgrowth and tumorigenesis. Inhibiting YAP1 activity with MGH-CP1, a recently developed TEAD inhibitor, impedes MDSC accumulation and suppresses tumor development. Our results identify the disrupted Hippo/YAP signaling as a major contributor to pRCC and suggest that targeting the disrupted Hippo pathway represents a plausible strategy to prevent and treat pRCC.

Synergistic Strategies for Lung Cancer Immunotherapy: Combining Phytochemicals and Immune-Checkpoint Inhibitors

Lung cancer remains one of the most widespread and deadliest malignant tumors globally, with a particularly high mortality rate among all cancers. Recently, immunotherapy, particularly immune checkpoint inhibitors (ICIs), has emerged as a crucial treatment strategy for lung cancer patients, following surgical intervention, radiotherapy, chemotherapy, and targeted drug therapies. However, the therapeutic limitations are caused owing to their low response rate and undesirable side effects such as immune-related pneumonitis. Therefore, developing new strategies to improve the efficacy of ICIs while minimizing immune-related adverse events will be crucial for cancer immunotherapy. The tumor immune microenvironment plays a significant role in the success of lung cancer immunotherapy, and the immunosuppressive characteristics of the immune microenvironment are one of the major obstacles to the poor immunotherapeutic effect. Phytochemicals, naturally occurring compounds in plants, have shown promise in enhancing cancer immunotherapy by remodeling the immunosuppressive microenvironment, offering the potential to increase the efficacy of ICIs. Therefore, this review summarizes the associated mechanisms of phytochemicals remodeling the immunosuppressive microenvironment in lung cancer. Additionally, the review will focus on the synergistic effects of combining phytochemicals with ICIs, aiming to improve anticancer efficacy and reduce side effects, which may hopefully offer novel strategies to overcome current limitations in immunotherapy.

Myeloid-Derived Suppressor Cells: Implications in Cancer Immunology and Immunotherapy

Myeloid-derived suppressor cells (MDSCs) are believed to be key promoters of tumor development and are recognized as a hallmark of cancer cells' ability to evade the immune system evasion. MDSC levels often increase in peripheral blood and the tumor microenvironment (TME). These cells exert immunosuppressive functions, weakening the anticancer immune surveillance system, in part by repressing T-cell immunity. Moreover, MDSCs may promote tumor progression and interact with cancer cells, increasing MDSC expansion and favoring an immunotolerant TME. This review analyzes the primary roles of MDSCs in cancer and T-cell immunity, discusses the urgent need to develop effective MDSC-targeted therapies, and highlights the potential synergistic combination of MDSC targeting with chimeric antigen receptors and immune checkpoint inhibitors.

Applications of mRNA Delivery in Cancer Immunotherapy

Cancer treatment is continually advancing, with immunotherapy gaining prominence as a standard modality that has markedly improved the management of various malignancies. Despite these advancements, the efficacy of immunotherapy remains variable, with certain cancers exhibiting limited response and patient outcomes differing considerably. Thus, enhancing the effectiveness of immunotherapy is imperative. A promising avenue is mRNA delivery, employing carriers such as liposomes, peptide nanoparticles, inorganic nanoparticles, and exosomes to introduce mRNA cargos encoding tumor antigens, immune-stimulatory, or immune-modulatory molecules into the tumor immune microenvironment (TIME). This method aims to activate the immune system to target and eradicate tumor cells. In this review, we introduce the characteristics and limitations of these carriers and summarize the application and mechanisms of currently prevalent cargos in mRNA-based tumor treatment. Additionally, given the significant clinical application of immune checkpoint inhibitors (ICIs) and chimeric antigen receptor (CAR)-based cell therapies in solid tumors (including melanoma, non-small-cell lung cancer, head and neck squamous cell carcinoma, triple-negative breast cancer, gastric cancer) and leukemia, which have become first-line treatments, we highlight and discuss recent progress in combining mRNA delivery with ICIs, CAR-T, CAR-NK, and CAR-macrophage therapies. This combination enhances the targeting capabilities and efficacy of ICIs and CAR-cell-based therapies, while also mitigating the long-term off-target toxicities associated with conventional methods. Finally, we analyze the limitations of current mRNA delivery systems, such as nuclease-induced mRNA instability, immunogenicity risks, complex carrier production, and knowledge gaps concerning dosing and safety. Addressing these challenges is crucial for unlocking the potential of mRNA in cancer immunotherapy. Overall, exploring mRNA delivery enriches our comprehension of cancer immunotherapy and holds promise for developing personalized and effective treatment strategies, potentially enhancing the immune responses of cancer patients and extending their survival time.

Cancer immunotherapy by silencing transcription factor c-Rel using peptide-based nanoparticles

Background

Cancer immunotherapy has shown promising results in the clinic, but it faces great challenges such as low response rates and low efficacy in solid tumors. c-Rel, a member of the nuclear factor (NF)-κB family, is a newly described immune checkpoint for myeloid-derived suppressor cells (MDSCs), which contribute to the formation of immune-suppressive tumor microenvironment and resistance to cancer immunotherapy. How to selectively target myeloid c-Rel for the treatment of cancer is not well established. In this study, we investigated the feasibility and efficacy of knocking down myeloid c-Rel with siRNA-loaded peptide-based nanoparticles as a new cancer immunotherapy strategy.

Methods

The knockdown of c-Rel gene by the siRNA-loaded peptide nanoparticles was confirmed on MDSCs in vitro and in vivo. The effects of c-Rel silencing on cell number and immune suppressive function of the murine bone marrow-derived MDSCs were then investigated. To evaluate the anti-tumor efficacy of the c-Rel siRNA loaded nanoparticles, female C57BL/6 mice with subcutaneous B16 tumor were treated with PBS, c-Rel siRNA loaded nanoparticles, control siRNA loaded nanoparticles or empty nanoparticles. The tumor growth and body weight of mice were monitored, and the numbers and immune activities of tumor infiltrated immune cells in different groups were analyzed at the end of the experiment. The immune function of MDSCs isolated from tumor bearing mice received different treatments were further investigated ex vivo by T cell proliferation assays.

Results

The c-Rel siRNA nanoparticles significantly reduced c-Rel expression in MDSCs, diminished both the number and immune suppressive function of MDSCs, and enhanced intratumor CD8+ T cell responses. Significantly reduced tumor growth was observed in mice treated with the c-Rel siRNA nanoparticles compared to control mice.

Conclusion

Our data indicates that peptide-based nanoparticles can be successfully utilized to target the myeloid immune checkpoint c-Rel for the treatment of cancer.

Growth Hormone Action as a Target in Cancer: Significance, Mechanisms, and Possible Therapies

Growth hormone (GH) is a pituitary-derived endocrine hormone required for normal postnatal growth and development. Hypo- or hypersecretion of endocrine GH results in 2 pathologic conditions, namely GH deficiency (GHD) and acromegaly. Additionally, GH is also produced in nonpituitary and tumoral tissues, where it acts rather as a cellular growth factor with an autocrine/paracrine mode of action. An increasingly persuasive and large body of evidence over the last 70 years concurs that GH action is implicit in escalating several cancer-associated events, locally and systemically. This pleiotropy of GH's effects is puzzling, but the association with cancer risk automatically raises a concern for patients with acromegaly and for individuals treated with GH. By careful assessment of the available knowledge on the fundamental concepts of cancer, suggestions from epidemiological and clinical studies, and the evidence from specific reports, in this review we aimed to help clarify the distinction of endocrine vs autocrine/paracrine GH in promoting cancer and to reconcile the discrepancies between experimental and clinical data. Along this discourse, we critically weigh the targetability of GH action in cancer-first by detailing the molecular mechanisms which posit GH as a critical node in tumor circuitry; and second, by enumerating the currently available therapeutic options targeting GH action. On the basis of our discussion, we infer that a targeted intervention on GH action in the appropriate patient population can benefit a sizable subset of current cancer prognoses.

Complement regulators as novel targets for anti-cancer therapy: A comprehensive review

Cancer remains a formidable global health challenge requiring the continued exploration of innovative therapeutic approaches. While traditional treatment strategies including surgery, chemotherapy, and radiation therapy have had some success, primarily in early-stage disease, the quest for more targeted, personalized, safer, and effective therapies remains an ongoing pursuit. Over the past decade, significant advances in the field of tumor immunology have dramatically shifted a focus towards immunotherapy, although the ability to harness and coopt the immune system to treat cancer is still just beginning to be realized. One important area that has yet to be fully explored is the complement system, an integral part of innate immunity that has gathered attention recently as a source of potential targets for anti-cancer therapy. The complement system has a complex and context dependent role in cancer biology in that it not only contributes to immune surveillance but also may promote tumor progression. Complement regulators, including CD46, CD55, CD59, and complement factor H, exercise defined control over complement activation, and have also been acknowledged for their role in the tumor microenvironment. This review explores the intricate role of complement regulators in cancer development and progression, examining their potential as therapeutic targets, current strategies, challenges, and the evolving landscape of clinical research.

TLR Agonist Nano Immune Therapy Clears Peritoneal and Systemic Ovarian Cancer

Intraperitoneal (IP) administration of immunogenic mesoporous silica nanoparticles (iMSN) in a mouse model of metastatic ovarian cancer promotes the development of tumor-specific CD8+ T cells and protective immunity. IP delivery of iMSN functionalized with the Toll-like receptor (TLR) agonists polyethyleneimine (PEI), CpG oligonucleotide, and monophosphoryl lipid A (MPLA) stimulated rapid uptake by all peritoneal myeloid subsets. Myeloid cells quickly transported iMSN to milky spots and fat-associated lymphoid clusters (FALCs) present in tumor-burdened adipose tissues, leading to a reduction in suppressive T cells and an increase in activated memory T cells. Two doses of iMSN cleared or reduced ovarian and colorectal cancer and protected against future tumor engraftment. In contrast, subcutaneous (SC) and intravenous (IV) delivery of iMSN were without therapeutic effect in mice with peritoneal metastases, supporting the need for activation of regional immune cells. Remarkably, intraperitoneal delivery of iMSN cleared subcutaneously implanted ovarian cancer, supporting homing of antigen specific T cells to extraperitoneal tumor sites.

Targeting myeloid-derived suppressor cells in the tumor microenvironment: potential therapeutic approaches for osteosarcoma

Osteosarcoma is a bone malignancy characterized by strong invasiveness and rapid disease progression. The tumor microenvironment of osteosarcoma contains various types of immune cells, including myeloid-derived suppressor cells, macrophages, T cells, and B cells. Imbalances of these immune cells can promote the proliferation and metastasis of osteosarcoma. Recent studies have indicated a substantial increase in the levels of myeloid-derived suppressor cells, an immune cell associated with immunosuppressive and pro-cancer effects, in the peripheral blood of patients with osteosarcoma. Moreover, the levels of the pro-inflammatory cytokine interleukin 18 are positively correlated with those of myeloid-derived suppressor cells in the peripheral blood of animal models of osteosarcoma. In this review, we explore the function of myeloid-derived suppressor cells in osteosarcoma based on the clinical diagnoses of patients with osteosarcoma and discuss future therapeutic approaches for targeting osteosarcoma. Targeting myeloid-derived suppressor cells represents a promising approach to improving the prognosis and survival rates of patients with osteosarcoma.

Research trends in glioma chemoradiotherapy resistance: a bibliometric analysis (2003-2023)

Background

Glioma is the most aggressive primary malignant tumor of the central nervous system, characterized by high recurrence rates and resistance to chemoradiotherapy, making therapeutic resistance a major challenge in neuro-oncology. Recent research emphasizes the role of the tumor microenvironment (TME) and immune modulation in glioma progression and resistance. Despite these advances, a comprehensive bibliometric analysis of research trends in glioma chemoradiotherapy resistance over the past two decades is lacking. This study aims to systematically evaluate the research landscape, identify emerging hotspots, and provide guidance for future investigations.

Methods

Articles on glioma chemoradiotherapy resistance published between 2003 and 2023 were retrieved from the Web of Science Core Collection, resulting in 4,528 publications. Bibliometric tools, including VOSviewer, CiteSpace, and R packages such as bibliometrix and ggplot2, were used to analyze co-authorship networks, keyword evolution, and citation bursts to identify collaboration patterns, thematic developments, and influential contributions.

Results

Publication output increased significantly between 2013 and 2022, peaking at 650 articles in 2022. Over 1,000 institutions from 88 countries contributed to this research. The United States, Switzerland, and Germany showed the highest citation impact, while China led in publication volume but demonstrated relatively lower citation influence. The research focus has shifted from traditional topics such as the "MGMT gene" to emerging areas including the "tumor microenvironment," "immune infiltration," and "nanoparticles." The androgen receptor was identified as a promising but underexplored therapeutic target.

Conclusions

Research on glioma chemoradiotherapy resistance has seen substantial growth, with increasing emphasis on immune modulation, the tumor microenvironment, and novel therapeutic targets such as the androgen receptor. This study represents the first comprehensive bibliometric analysis of this field, providing a detailed overview of research trends and potential directions for future studies. The findings highlight the need for strengthened international collaboration and multidisciplinary approaches to address the challenges of therapeutic resistance in glioma.

Immunotherapy in gastric cancer-A systematic review

Background

Gastric Cancer (GC) is the 5th most prevalent and 4th most deadly neoplasm globally. Immunotherapy has emerged as a promising treatment approach in GC, potentially improving positive clinical outcomes while addressing the limitations of conventional therapies. GC immunotherapy modalities consist of adoptive cell therapy (ACT), cancer vaccines, and immune checkpoint inhibitors (ICI).

Objectives

This systematic review aims to provide an overview of the advances in immune-based therapeutic approaches in GC, highlighting the potential of this therapy as a strategy for GC treatment.

Methods

Key studies investigating several immunotherapeutic agents and combination therapies were searched in PUBMED and included in this study. Specific cancer outcomes related to disease progression or survival were analyzed.

Results

After screening 236 studies, the results revealed that immunotherapy, particularly the ICI pembrolizumab, demonstrated promising efficacy in the treatment of GC, as several studies reported improved OS, PFS, and objective response rate with the use of pembrolizumab alone or in combination with other treatment modalities.

Conclusion

Safety analysis showed that immunotherapy was mostly well-tolerated, with manageable adverse events and relatively good safety profiles. Nonetheless, further research is required to understand the mechanisms of tumor resistance better and identify predictive biomarkers that can direct treatment optimization.

Harnessing the tumor microenvironment: targeted cancer therapies through modulation of epithelial-mesenchymal transition

The tumor microenvironment (TME) is integral to cancer progression, impacting metastasis and treatment response. It consists of diverse cell types, extracellular matrix components, and signaling molecules that interact to promote tumor growth and therapeutic resistance. Elucidating the intricate interactions between cancer cells and the TME is crucial in understanding cancer progression and therapeutic challenges. A critical process induced by TME signaling is the epithelial-mesenchymal transition (EMT), wherein epithelial cells acquire mesenchymal traits, which enhance their motility and invasiveness and promote metastasis and cancer progression. By targeting various components of the TME, novel investigational strategies aim to disrupt the TME's contribution to the EMT, thereby improving treatment efficacy, addressing therapeutic resistance, and offering a nuanced approach to cancer therapy. This review scrutinizes the key players in the TME and the TME's contribution to the EMT, emphasizing avenues to therapeutically disrupt the interactions between the various TME components. Moreover, the article discusses the TME's implications for resistance mechanisms and highlights the current therapeutic strategies toward TME modulation along with potential caveats.

Myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment and their targeting in cancer therapy

The advent of immunotherapy represents a significant breakthrough in cancer treatment, with immune checkpoint inhibitors (ICIs) targeting PD-1 and CTLA-4 demonstrating remarkable therapeutic efficacy. However, patient responses to immunotherapy vary significantly, with immunosuppression within the tumor microenvironment (TME) being a critical factor influencing this variability. Immunosuppression plays a pivotal role in regulating cancer progression, metastasis, and reducing the success rates of immunotherapy. Myeloid-derived suppressor cells (MDSCs), due to their potent immunosuppressive capabilities, emerged as major negative regulators within the TME, facilitating tumor immune evasion by modulating various immune cells. In addition to their immunosuppressive functions, MDSCs also promote tumor growth and metastasis through non-immunological mechanisms, such as angiogenesis and the formation of pre-metastatic niches. Consequently, MDSCs in the TME are key regulators of cancer immune responses and potential therapeutic targets in cancer treatment. This review describes the origins and phenotypes of MDSCs, their biological roles in tumor progression, and regulatory mechanisms, with a focus on current therapeutic approaches targeting tumor-associated MDSCs. Furthermore, the synergistic effects of targeting MDSCs in combination with immunotherapy are explored, aiming to provide new insights and directions for cancer therapy.

Biochemistry, pharmacology, and in vivo function of arginases

The enzyme arginase catalyzes the hydrolysis of l-arginine into l-ornithine and urea. The 2 existing isoforms Arg1 and Arg2 exhibit different cellular localizations and metabolic functions. Arginase activity is crucial for nitrogen detoxification in the urea cycle, synthesis of polyamines, and control of l-arginine bioavailability and nitric oxide (NO) production. Despite significant progress in the understanding of the biochemistry and function of arginases, several open questions remain. Recent studies have revealed that the regulation and function of Arg1 and Arg2 are cell type-specific, species-specific, and profoundly different in mice and humans. The main differences are in the distribution and function of Arg1 and Arg2 in immune and erythroid cells. Contrary to what was previously thought, Arg1 activity appears to be only partially related to vascular NO signaling under homeostatic conditions in the vascular wall, but its expression is increased under disease conditions and may be targeted by treatment with arginase inhibitors. Arg2 appears to be mainly a catabolic enzyme involved in the synthesis of l-ornithine, polyamine, and l-proline but may play a putative role in blood pressure control, at least in mice. The immunosuppressive role of arginase-mediated arginine depletion is a promising target for cancer treatment. This review critically revises and discusses the biochemistry, pharmacology, and in vivo function of arginases, focusing on the insights gained from the analysis of cell-specific Arg1 and Arg2 knockout mice and human studies using arginase inhibitors or pegylated recombinant arginase. SIGNIFICANCE STATEMENT: Further basic and translational research is needed to deepen our understanding of the regulation of Arg1 and Arg2 in different cell types in consideration of their localization, species-specificity, and multiple biochemical and physiological roles. This will lead to better pharmacological strategies to target arginase activity in liver, cardiovascular, hematological, immune/infectious diseases, and cancer.

Anti-PD-1 antibody (Tislelizumab) combined with gemcitabine and oxaliplatin for extranodal NK/T-cell lymphoma failing asparaginase: A multicenter phase II trial

BACKGROUND

Extranodal natural killer/T-cell lymphoma (ENKTCL) is almost always fatal after the failure of asparaginase. This phase II study aimed to investigate the efficacy and safety of tislelizumab combined with gemcitabine and oxaliplatin (Tisle-GemOx) in patients with ENKTCL failing asparaginase.

METHODS

Eligible patients received Tisle-GemOx as initial induction for 6-8 cycles at 21-day intervals. Responders continued tislelizumab maintenance every two months for two years. The primary endpoint was the best complete response rate (CRR).

RESULTS

As of September 2023, 32 patients were enrolled in our study. Among the 30 efficacy-evaluable patients, the best CRR was 60 %, meeting the primary efficacy endpoint. With a median follow-up of 22.6 months, the median progression-free survival (PFS) was 7.4 months and the 1-year PFS rate was 46.4 %. Subgroup analyses showed that shorter PFS was associated with previous lines of chemotherapy ≥ 2 (P = 0.034) and concomitant hemophagocytic lymphohistiocytosis (P = 0.040). Pseudo-progression was observed in three patients (10 %). The most common grade ≥ 3 toxicities were lymphopenia (25 %) and anemia (15.6 %).

CONCLUSIONS

Tisle-GemOx exhibits promising anti-tumor activity and manageable toxicities as a salvage therapy for ENKTCL failing asparaginase. Further long-term follow-up is necessary to evaluate the durability of the response with tislelizumab maintenance in this patient population.

The interplay between the tumor microenvironment and tumor-derived small extracellular vesicles in cancer development and therapeutic response

The tumor microenvironment (TME) plays an essential role in tumor cell survival by profoundly influencing their proliferation, metastasis, immune evasion, and resistance to treatment. Extracellular vesicles (EVs) are small particles released by all cell types and often reflect the state of their parental cells and modulate other cells' functions through the various cargo they transport. Tumor-derived small EVs (TDSEVs) can transport specific proteins, nucleic acids and lipids tailored to propagate tumor signals and establish a favorable TME. Thus, the TME's biological characteristics can affect TDSEV heterogeneity, and this interplay can amplify tumor growth, dissemination, and resistance to therapy. This review discusses the interplay between TME and TDSEVs based on their biological characteristics and summarizes strategies for targeting cancer cells. Additionally, it reviews the current issues and challenges in this field to offer fresh insights into comprehending tumor development mechanisms and exploring innovative clinical applications.

Association of immunosuppressive CD45+CD33+CD14- CD10-HLA-DR-/low neutrophils with poor prognosis in patients with lymphoma and their expansion and activation through STAT3/arginase-1 pathway in vitro

Objective

This study aimed to explore the clinical significance of CD45+CD33+CD14-CD10-HLA-DR-/low neutrophils (Cluster of Differentiation 10 [CD10-] neutrophils) in B-cell non-Hodgkin's lymphoma (B-NHL). An amplification system of CD10- neutrophils in vitro was constructed using cytokines, and the mechanisms underlying the cytokine-induced expansion and activation of the CD10- neutrophil subpopulation were investigated.

Material and Methods

We identified a novel suppressive cell population known as CD10- neutrophils in the peripheral blood of patients with B-NHL in different statuses by flow cytometry and found it to be correlated with interleukin-6 levels, T cell counts, and plasma arginase-1 (Arg-1) levels. We then verified the effect of CD10- neutrophil expression on the prognosis of patients with B-NHL. Furthermore, we described a clinically compatible method for generating granulocyte populations rich in CD10- neutrophils using cultures of peripheral blood-isolated neutrophils supplemented with cytokines in vitro. Arg-1 expression was detected in neutrophils before and after induction by cytokines through reverse-transcription polymerase chain reaction, enzyme-linked immunosorbent assay, and flow cytometry. T-cell proliferation and apoptosis were measured by carboxyfluorescein succinimidyl ester assay and Annexin V-Propidium Iodide stains, and induced cells were exposed to Arg-1 inhibitor and ruxolitinib. signal transducer and activator of transcription 3 (STAT3)/Arg-1 signaling was studied mainly by western blot and chromatin immunoprecipitation experiments.

Results

We established a correlation between high CD10- neutrophil levels and poorer survival outcomes in patients with B-NHL. Moreover, CD10- neutrophils were positively correlated with interleukin (IL)-6, T-reg cells, and plasma Arg-1 levels and negatively correlated with the absolute number of total T cells. Granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor, and IL-6 could all induce the expansion of CD10- neutrophil phenotype cells in vitro, which exhibit typical immature cellular morphology, and the combination of IL-6 and GM-CSF was the most effective. We confirmed that the STAT3/Arg-1 signaling pathway could be a critical mechanism regulating CD10- neutrophil-mediated immunosuppression in vitro.

Conclusion

CD10- neutrophils exhibited basic characteristics similar to conventional myeloid-derived suppressor cells. Our observations provide a promising STAT3 or Arg-1 targeting strategy for B-NHL and an important method for generating remarkably amounts of inhibitory granulocyte populations rich in CD10- neutrophils for immunotherapy.

Role of myeloid-derived suppressor and Th17/Treg cells in post-COVID-19 Rhino-Orbital mucormycosis cases

Background: Rhino-Orbital-Cerebral Mucormycosis (ROCM) cases increased sharply in India during the second COVID-19 wave. Due to uncontrolled hyperglycemia, prolonged steroid use, and high ferritin levels, the immune system was dysregulated throughout this surge.

Methods: Our study examined post-COVID-19 ROCM patients' T regulatory cell (Treg), T helper 17 cell (Th17) and Myeloid derived suppressor cell (MDSC) levels before and after three months of treatment. T cell activation and MDSC profile were measured in peripheral blood from 20 post-COVID-19 mucormycosis patients and 20 age-matched controls.

Results: Compared to controls, cases had significantly greater Th17 cells (CD4+IL-23R+) before and after treatment (p < 0.05), with no significant change between pre- and post-treatment. In pretreatment cases, Treg cells (CD4+CD25+FoxP3+) were lower than controls, but dramatically increased (p < 0.05) following treatment. Further, these patients had significantly higher rates of monocytic (m) MDSCs (CD14+HLA-DRlow/-) compared to healthy persons (p < 0.05). Interestingly, after three months of treatment, mMDSC levels dropped to levels similar to healthy controls. Similarly, ROCM patients had higher levels of granulocytic (g) MDSCs (HLA-DRlow/-CD33+CD11b+CD66+) than healthy controls, although these levels normalized after three months. Patients had considerably greater expression levels of RORγt, TGF-β, and IL-10 mRNA before therapy compared to healthy controls. FoxP3 and Arg-1 mRNA expression was lower in pretreatment patients than in healthy people. After treatment, these individuals' IL-10, FoxP3, and Arg-1 mRNA expression increased.

Conclusion: MDSCs may play a role in mucormycosis immunological dysregulation, suggesting that restoring balance may improve patient outcomes.

Myeloid-derived suppressor cells in cancer: Current knowledge and future perspectives

MDSCs (myeloid-derived suppressor cells) are crucial for immune system evasion in cancer. They accumulate in peripheral blood and tumor microenvironment, suppressing immune cells like T-cells, natural killer cells and dendritic cells. They promote tumor angiogenesis and metastasis by secreting cytokines and growth factors and contribute to a tumor-promoting environment. The accumulation of MDSCs in cancer patients has been linked to poor prognosis and resistance to various cancer therapies. Targeting MDSCs and their immunosuppressive mechanisms may improve treatment outcomes and enhance immune surveillance by developing drugs that inhibit MDSC function, by preventing their accumulation and by disrupting the tumor-promoting environment. This review presents a detailed overview of the MDSC research in cancer with regulation of their development and function. The relevance of MDSC as a prognostic and predictive biomarker in different types of cancers, along with recent advancements on the therapeutic approaches to target MDSCs are discussed in detail.

Host ANGPTL2 establishes an immunosuppressive tumor microenvironment and resistance to immune checkpoint therapy

Use of immune checkpoint inhibitors (ICIs) as cancer immunotherapy has advanced rapidly in the clinic; however, mechanisms underlying resistance to ICI therapy, including impaired T cell infiltration, low immunogenicity, and tumor "immunophenotypes" governed by the host, remain unclear. We previously reported that in some cancer contexts, tumor cell-derived angiopoietin-like protein 2 (ANGPTL2) has tumor-promoting functions. Here, we asked whether ANGPTL2 deficiency could enhance antitumor ICI activity in two inflammatory contexts: a murine syngeneic model of colorectal cancer and a mouse model of high-fat diet (HFD)-induced obesity. Systemic ANGPTL2 deficiency potentiated ICI efficacy in the syngeneic model, supporting an immunosuppressive role for host ANGPTL2. Relevant to the mechanism, we found that ANGPTL2 induces pro-inflammatory cytokine production in adipose tissues, driving generation of myeloid-derived suppressor cells (MDSCs) in bone marrow and contributing to an immunosuppressive tumor microenvironment and resistance to ICI therapy. Moreover, HFD-induced obese mice showed impaired responsiveness to ICI treatment, suggesting that obesity-induced chronic inflammation facilitated by high ANGPTL2 expression blocks ICI antitumor effects. Our findings overall provide novel insight into protumor ANGPTL2 functions and illustrate the essential role of the host system in ICI responsiveness.

Estimate the relationship between CXCR4-SDF-1 axis and inhibitory molecules (CTLA4 and PD-1) in patients with colon cancer

Colon neoplasia is one of the major malignancies in industrialized countries due to their Western-style food habits. It accounts for more than 50% of the population developing adenomatous polyps by the age of 70 years, but 10% of cancers in developed countries. The aim of this study was to evaluate the pathological role of the C-X-C chemokine receptor type 4/stromal-derived factor 1 axis (CXCR4-SDF-1 axis), and the inhibitory molecules PD-1 and cytotoxic T-lymphocyte associated protein 4 (CTLA-4) in postoperative colon cancer patients undergoing treatment with chemotherapy (oxaliplatin and capecitabine) and estimate the correlation between these studied factors to deeply understand the basic mechanisms and potential diagnostic or therapeutic effects. The study involved 90 patients, including 50 colon cancer patients (male and female, aged 35-65) diagnosed by oncologists at Al-Ramadi Hospital, Ramadi, Iraq. All patients underwent surgical resection and received four cycles of chemotherapy with oxaliplatin (85 mg every 21 days) and capecitabine (6 grams daily for 21 days). Additionally, 40 age- and sex-matched individuals served as the control group. For each participant, CXCR4 and SDF-1 levels were measured using ELISA and the gene expression of CTLA-4 and PD-1 were measured using RT-PCR. The colon cancer patient group showed significantly lower levels of CXCR4 and SDF-1 compared to control groups (0.163±0.012 vs 0.376±0.025 pg/mL and 0.376±0.025 vs 0.699±0.110 pg/mL, respectively, both had p=0.001). Moreover, the colon cancer patient group had significantly lower expression of PD-1 and CTLA4 compared to control group (0.102±0.029-fold vs 1.199±0.391-fold, p=0.02; and 0.302±0.140-fold vs 1.441±0.334-fold, p=0.008, respectively). In conclusion, the results suggest that CXCR4 and SDF-1 appear promising as diagnostic markers for distinguishing colon cancer patients from healthy conditions.

Blood based immune biomarkers associated with clinical frailty scale in older patients with melanoma receiving checkpoint inhibitor immunotherapy

INTRODUCTION

Immunotherapy with checkpoint inhibition (ICI) is increasingly prescribed to older patients with cancer. High age, especially in combination with frailty, has been associated to immune senescence, which is the age-related decline in immune function, thereby possibly hindering ICI effectiveness. This cross-sectional study aimed to assess whether blood cell immune senescence markers are associated with age, frailty and response to anti-PD-1 treatment in older patients with metastatic melanoma.

METHODS

In a prospective observational study, sixty patients with stage IIIC or IV melanoma undergoing anti-PD1 treatment were categorized into young (< 65 years; n = 22), old (> 65 years) without frailty (n = 19), and old with frailty (n = 19). In-depth immune cell phenotyping was performed in baseline blood samples (prior to treatment) using multispectral flow cytometry and compared between groups and with immunotherapy treatment response. Antigen-presenting cell capacity was evaluated using mixed lymphocyte reaction and T cell proliferative potential was assessed using PHA proliferation assay.

RESULTS

No significant differences in treatment response rates were observed across age groups. Older patients, irrespective of frailty, showed lower levels of naïve CD8 + T cells, with the old and frail group also exhibiting reduced tissue-resident effector memory CD8 + T cells and CD8 + mucosal associated invariant T (MAIT) cells. These differences were not associated with treatment outcomes. T cell proliferation and antigen-presenting cell capacities did not differ across groups.

CONCLUSION

Several ageing and frailty associated changes were detected among circulating immune cells in blood but were not associated with response to immunotherapy in our study. While these findings suggest that the level of frailty and ageing may not necessarily preclude the efficacy of ICI therapy, further investigation is needed to fully understand the impact of frailty and ageing on immunotherapy.

Leukocyte immunoglobulin-like receptor B4 (LILRB4) in acute myeloid leukemia: From prognostic biomarker to immunotherapeutic target

ABSTRACT

Leukocyte immunoglobulin-like receptor (LILR) B4 (also known as ILT3/CD85k) is an immune checkpoint protein that is highly expressed in solid tumors and hematological malignancies and plays a significant role in the pathophysiology of cancer. LILRB4 is highly expressed in acute myeloid leukemia (AML), and this phenotype is associated with adverse patient outcomes. Its differential expression in tumors compared to normal tissues, its presence in tumor stem cells, and its multifaceted roles in tumorigenesis position it as a promising therapeutic target in AML. Currently, several immunotherapies targeting LILRB4 are undergoing clinical trials. This review summarizes advancements made in the study of LILRB4 in AML, focusing on its structure, ligands, expression, and significance in normal tissues and AML; its protumorigenic effects and mechanisms in AML; and the application of LILRB4-targeted therapies in AML. These insights highlight the potential advantages of LILRB4 as an immunotherapeutic target in the context of AML.

The role of hypoxic microenvironment in autoimmune diseases

The hypoxic microenvironment, characterized by significantly reduced oxygen levels within tissues, has emerged as a critical factor in the pathogenesis and progression of various autoimmune diseases (AIDs). Central to this process is the hypoxia-inducible factor-1 (HIF-1), which orchestrates a wide array of cellular responses under low oxygen conditions. This review delves into the multifaceted roles of the hypoxic microenvironment in modulating immune cell function, particularly highlighting its impact on immune activation, metabolic reprogramming, and angiogenesis. Specific focus is given to the mechanisms by which hypoxia contributes to the development and exacerbation of diseases such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), multiple sclerosis (MS), and dermatomyositis (DM). In these conditions, the hypoxic microenvironment not only disrupts immune tolerance but also enhances inflammatory responses and promotes tissue damage. The review also discusses emerging therapeutic strategies aimed at targeting the hypoxic pathways, including the application of HIF-1α inhibitors, mTOR inhibitors, and other modulators of the hypoxic response. By providing a comprehensive overview of the interplay between hypoxia and immune dysfunction in AIDs, this review offers new perspectives on the underlying mechanisms of these diseases and highlights potential avenues for therapeutic intervention.

Targeted modulation of myeloid-derived suppressor cells in the tumor microenvironment: Implications for cancer therapy

Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population of immature myeloid cells originating from the bone marrow, known for their potent immunosuppressive functions that contribute to tumor immune evasion and progression. This paper provides a comprehensive analysis of the multifaceted interactions between MDSCs and tumors, exploring their distinct phenotypes and immunosuppressive mechanisms. Key roles of MDSCs in tumor biology are discussed, including their involvement in the formation of the pre-metastatic niche, facilitation of angiogenesis, enhancement of vascular permeability, suppression of tumor cell apoptosis, and promotion of resistance to cancer therapies. Additionally, the review highlights recent advances in the development of MDSC-targeting therapies, with a focus on their potential to enhance anti-tumor immunity. The therapeutic potential of Traditional Chinese Medicine (TCM) in modulating MDSC quantity and function is also explored, suggesting a novel approach to cancer treatment by integrating traditional and modern therapeutic strategies.

Integrated analysis of bulk and single-cell RNA sequencing reveals the impact of nicotinamide and tryptophan metabolism on glioma prognosis and immunotherapy sensitivity

BACKGROUND

Nicotinamide and tryptophan metabolism play important roles in regulating tumor synthesis metabolism and signal transduction functions. However, their comprehensive impact on the prognosis and the tumor immune microenvironment of glioma is still unclear. The purpose of this study was to investigate the association of nicotinamide and tryptophan metabolism with prognosis and immune status of gliomas and to develop relevant models for predicting prognosis and sensitivity to immunotherapy in gliomas.

METHODS

Bulk and single-cell transcriptome data from TCGA, CGGA and GSE159416 were obtained for this study. Gliomas were classified based on nicotinamide and tryptophan metabolism, and PPI network associated with differentially expressed genes was established. The core genes were identified and the risk model was established by machine learning techniques, including univariate Cox regression and LASSO regression. Then the risk model was validated with data from the CGGA. Finally, the effects of genes in the risk model on the biological behavior of gliomas were verified by in vitro experiments.

RESULTS

The high nicotinamide and tryptophan metabolism is associated with poor prognosis and high levels of immune cell infiltration in glioma. Seven of the core genes related to nicotinamide and tryptophan metabolism were used to construct a risk model, and the model has good predictive ability for prognosis, immune microenvironment, and response to immune checkpoint therapy of glioma. We also confirmed that high expression of TGFBI can lead to an increased level of migration, invasion, and EMT of glioma cells, and the aforementioned effect of TGFBI can be reduced by FAK inhibitor PF-573,228.

CONCLUSIONS

Our study evaluated the effects of nicotinamide and tryptophan metabolism on the prognosis and tumor immune microenvironment of glioma, which can help predict the prognosis and sensitivity to immunotherapy of glioma.

Myeloid-Derived Suppressor Cells in Bladder Cancer: An Emerging Target

Bladder cancer remains a prevalent and challenging malignancy. Myeloid-derived suppressor cells (MDSCs) have emerged as key contributors to the immunosuppressive tumor microenvironment, facilitating tumor progression, immune evasion, and resistance to therapies. This review explores the role of MDSC in bladder cancer, highlighting their involvement in immune regulation; tumor progression; and resistance to therapies such as bacillus Calmette-Guérin (BCG) therapy, chemotherapy, and immune checkpoint inhibitors (ICIs). We also discuss their potential as biomarkers and therapeutic targets, with current evidence suggesting that targeting MDSCs, either alone or in combination with existing treatments such as BCG and ICIs, may enhance anti-tumor immunity and improve clinical outcomes. However,, challenges remain, particularly regarding the identification and therapeutic modulation of MDSC subpopulations. Further research is warranted to fully elucidate their role in bladder cancer and to optimize MDSC-targeted therapies.

Tumour Immunotherapy and Applications of Immunological Products: A Review of Literature

Malignant tumors, characterized by uncontrolled cell proliferation, are a leading global health challenge, responsible for over 9.7 million deaths in 2022, with new cases expected to rise to 35 million annually by 2050. Immunotherapy is preferred to other cancer therapies, offering precise targeting of malignant cells while simultaneously strengthening the immune system's complex responses. Advances in this novel field of science have been closely linked to a deeper knowledge of tumor biology, particularly the intricate interplay between tumor cells, the immune system, and the tumor microenvironment (TME), which are central to cancer progression and immune evasion. This review offers a comprehensive analysis of the molecular mechanisms that govern these interactions, emphasizing their critical role in the development of effective immunotherapeutic products. We critically evaluate the current immunotherapy approaches, including cancer vaccines, adoptive T cell therapies, and cytokine-based treatments, highlighting their efficacy and safety. We also explore the latest advancements in combination therapies, which synergistically integrate multiple immunotherapeutic strategies to overcome resistance and enhance therapeutic outcomes. This review offers key insights into the future of cancer immunotherapy with a focus on advancing more effective and personalized treatment strategies.

Cancer Vaccines: Recent Insights and Future Directions

The field of cancer immunotherapy has seen incredible advancements in the past decades. mRNA-based cancer vaccines generating de novo T cell responses, particularly against tumor-specific antigens (TSAs), have demonstrated promising clinical outcomes and overcome diverse challenges. Despite the high potential of neoantigens to provide personalized immunotherapies through their tumor specificity and immunogenicity, challenges related to the scarcity of immunogenic neoepitopes have prompted continuous research towards finding new tumor-associated antigens (TAAs) and broader therapeutic frameworks, which may now learn from the genuine successes obtained with neoantigens. As an example, human endogenous retroviruses (HERVs) have emerged as potential alternatives to tumor neoantigens due to their high tumoral expression and ability to elicit both T cell reactivity and B cell responses associated with the efficacy of existing immunotherapies. This review aims to assess the status and limitations of TSA-directed mRNA cancer vaccines and the lessons that can be derived from these and checkpoint inhibitor studies to guide TAA vaccine development. We expect that shared B cell, CD4 and CD8 T cell antigen presentation will be key to stimulate continuous T cell expansion and efficacy for tumors that do not contain pre-existing tertiary lymphoid structures. When these structures are present in highly mutated tumors, the current checkpoint-based immunotherapies show efficacy even in immune privileged sites, and vaccines may hold the key to broaden efficacy to more tumor types and stages.

Multi-stage mechanisms of tumor metastasis and therapeutic strategies

The cascade of metastasis in tumor cells, exhibiting organ-specific tendencies, may occur at numerous phases of the disease and progress under intense evolutionary pressures. Organ-specific metastasis relies on the formation of pre-metastatic niche (PMN), with diverse cell types and complex cell interactions contributing to this concept, adding a new dimension to the traditional metastasis cascade. Prior to metastatic dissemination, as orchestrators of PMN formation, primary tumor-derived extracellular vesicles prepare a fertile microenvironment for the settlement and colonization of circulating tumor cells at distant secondary sites, significantly impacting cancer progression and outcomes. Obviously, solely intervening in cancer metastatic sites passively after macrometastasis is often insufficient. Early prediction of metastasis and holistic, macro-level control represent the future directions in cancer therapy. This review emphasizes the dynamic and intricate systematic alterations that occur as cancer progresses, illustrates the immunological landscape of organ-specific PMN creation, and deepens understanding of treatment modalities pertinent to metastasis, thereby identifying some prognostic and predictive biomarkers favorable to early predict the occurrence of metastasis and design appropriate treatment combinations.

Spatial multiplexed immunofluorescence analysis reveals coordinated cellular networks associated with overall survival in metastatic osteosarcoma

Patients diagnosed with advanced osteosarcoma, often in the form of lung metastases, have abysmal five-year overall survival rates. The complexity of the osteosarcoma immune tumor microenvironment has been implicated in clinical trial failures of various immunotherapies. The purpose of this exploratory study was to spatially characterize the immune tumor microenvironment of metastatic osteosarcoma lung specimens. Knowledge of the coordinating cellular networks within these tissues could then lead to improved outcomes when utilizing immunotherapy for treatment of this disease. Importantly, various cell types, interactions, and cellular neighborhoods were associated with five-year survival status. Of note, increases in cellular interactions between T lymphocytes, positive for programmed cell death protein 1, and myeloid-derived suppressor cells were observed in the 5-year deceased cohort. Additionally, cellular neighborhood analysis identified an Immune-Cold Parenchyma cellular neighborhood, also associated with worse 5-year survival. Finally, the Osteosarcoma Spatial Score, which approximates effector immune activity in the immune tumor microenvironment through the spatial proximity of immune and tumor cells, was increased within 5-year survivors, suggesting improved effector signaling in this patient cohort. Ultimately, these data represent a robust spatial multiplexed immunofluorescence analysis of the metastatic osteosarcoma immune tumor microenvironment. Various communication networks, and their association with survival, were described. In the future, identification of these networks may suggest the use of specific, combinatory immunotherapeutic strategies for improved anti-tumor immune responses and outcomes in osteosarcoma.

Re-Assessing the Role of Platelet Activating Factor and Its Inflammatory Signaling and Inhibitors in Cancer and Anti-Cancer Strategies

Since 2000s, we have outlined the multifaceted role of inflammation in several aspects of cancer, via specific inflammatory mediators, including the platelet activating factor (PAF) and PAF-receptor (PAFR) related signaling, which affect important inflammatory junctions and cellular interactions that are associated with tumor-related inflammatory manifestations. It is now well established that disease-related unresolved chronic inflammatory responses can promote carcinogenesis. At the same time, tumors themselves are able to promote their progression and metastasis, by triggering an inflammation-related vicious cycle, in which PAF and its signaling play crucial role(s), which usually conclude in tumor growth and angiogenesis. In parallel, new evidence suggests that PAF and its signaling also interact with several inflammation-related cancer treatments by inducing an antitumor immune response or, conversely, promoting tumor recurrence. Within this review article, the current knowledge and future perspectives of the implication of PAF and its signaling in all these important aspects of cancer are thoroughly re-assessed. The potential beneficial role of PAF-inhibitors and natural or synthetic modulators of PAF-metabolism against tumors, tumor progression and metastasis are evaluated. Emphasis is given to natural and synthetic molecules with dual anti-PAF and anti-cancer activities (Bio-DAPAC-tives), with proven evidence of their antitumor potency through clinical trials, as well as on metal-based anti-inflammatory mediators that constitute a new class of potent inhibitors. The way these compounds may promote anti-tumor effects and modulate the inflammatory cellular actions and immune responses is also discussed. Limitations and future perspectives on targeting of PAF, its metabolism and receptor, including PAF-related inflammatory signaling, as part(s) of anti-tumor strategies that involve inflammation and immune response(s) for an improved outcome, are also evaluated.

Pre-metastatic niche: formation, characteristics and therapeutic implication

Distant metastasis is a primary cause of mortality and contributes to poor surgical outcomes in cancer patients. Before the development of organ-specific metastasis, the formation of a pre-metastatic niche is pivotal in promoting the spread of cancer cells. This review delves into the intricate landscape of the pre-metastatic niche, focusing on the roles of tumor-derived secreted factors, extracellular vesicles, and circulating tumor cells in shaping the metastatic niche. The discussion encompasses cellular elements such as macrophages, neutrophils, bone marrow-derived suppressive cells, and T/B cells, in addition to molecular factors like secreted substances from tumors and extracellular vesicles, within the framework of pre-metastatic niche formation. Insights into the temporal mechanisms of pre-metastatic niche formation such as epithelial-mesenchymal transition, immunosuppression, extracellular matrix remodeling, metabolic reprogramming, vascular permeability and angiogenesis are provided. Furthermore, the landscape of pre-metastatic niche in different metastatic organs like lymph nodes, lungs, liver, brain, and bones is elucidated. Therapeutic approaches targeting the cellular and molecular components of pre-metastatic niche, as well as interventions targeting signaling pathways such as the TGF-β, VEGF, and MET pathways, are highlighted. This review aims to enhance our understanding of pre-metastatic niche dynamics and provide insights for developing effective therapeutic strategies to combat tumor metastasis.

Unlocking the tumor-immune microenvironment in osteosarcoma: insights into the immune landscape and mechanisms

Osteosarcoma has a unique tumor microenvironment (TME), which is characterized as a complex microenvironment comprising of bone cells, immune cells, stromal cells, and heterogeneous vascular structures. These elements are intricately embedded in a mineralized extracellular matrix, setting it apart from other primary TMEs. In a state of normal physiological function, these cell types collaborate in a coordinated manner to maintain the homeostasis of the bone and hematopoietic systems. However, in the pathological condition, i.e., neoplastic malignancies, the tumor-immune microenvironment (TIME) has been shown to promote cancer cells proliferation, migration, apoptosis and drug resistance, as well as immune escape. The intricate and dynamic system of the TIME in osteosarcoma involves crucial roles played by various infiltrating cells, the complement system, and exosomes. This complexity is closely associated with tumor cells evading immune surveillance, experiencing uncontrolled proliferation, and facilitating metastasis. In this review, we elucidate the intricate interplay between diverse cell populations in the osteosarcoma TIME, each contributing uniquely to tumor progression. From chondroblastic and osteoblastic osteosarcoma cells to osteoclasts, stromal cells, and various myeloid and lymphoid cell subsets, the comprehensive single-cell analysis provides a detailed roadmap of the complex osteosarcoma ecosystem. Furthermore, we summarize the mutations, epigenetic mechanisms, and extracellular vesicles that dictate the immunologic landscape and modulate the TIME of osteosarcoma. The perspectives of the clinical implementation of immunotherapy and therapeutic approaches for targeting immune cells are also intensively discussed.

Eliminating a barrier: Aiming at VISTA, reversing MDSC-mediated T cell suppression in the tumor microenvironment

Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment by producing remarkable clinical outcomes for patients with various cancer types. However, only a subset of patients benefits from immunotherapeutic interventions due to the primary and acquired resistance to ICIs. Myeloid-derived suppressor cells (MDSCs) play a crucial role in creating an immunosuppressive tumor microenvironment (TME) and contribute to resistance to immunotherapy. V-domain Ig suppressor of T cell activation (VISTA), a negative immune checkpoint protein highly expressed on MDSCs, presents a promising target for overcoming resistance to current ICIs. This article provides an overview of the evidence supporting VISTA's role in regulating MDSCs in shaping the TME, thus offering insights into how to overcome immunotherapy resistance.

Myeloid‑derived suppressor cells: Key immunosuppressive regulators and therapeutic targets in colorectal cancer (Review)

Globally, colorectal cancer (CRC) is the third most common type of cancer. CRC has no apparent symptoms in the early stages of disease, and most patients receive a confirmed diagnosis in the middle or late disease stages. The incidence of CRC continues to increase, and the affected population tends to be younger. Therefore, determining how to achieve an early CRC diagnosis and treatment has become a top priority for prolonging patient survival. Myeloid‑derived suppressor cells (MDSCs) are a group of bone marrow‑derived immuno‑negative regulatory cells that are divided into two subpopulations, polymorphonuclear‑MDSCs and monocytic‑MDSCs, based on their phenotypic similarities to neutrophils and monocytes, respectively. These cells can inhibit the immune response and promote cancer cell metastasis in the tumour microenvironment (TME). A large aggregation of MDSCs in the TME is often a marker of cancer and a poor prognosis in inflammatory diseases of the intestine (such as colonic adenoma and ulcerative colitis). In the present review, the phenotypic classification of MDSCs in the CRC microenvironment are first discussed. Then, the amplification, role and metastatic mechanism of MDSCs in the CRC TME are described, focusing on genes, gene modifications, proteins and the intestinal microenvironment. Finally, the progress in CRC‑targeted therapies that aim to modulate the quantity, function and structure of MDSCs are summarized in the hope of identifying potential screening markers for CRC and improving CRC prognosis and therapeutic options.

Exploring potential roles of long non-coding RNAs in cancer immunotherapy: a comprehensive review

Cancer treatment has long been fraught with challenges, including drug resistance, metastasis, and recurrence, making it one of the most difficult diseases to treat effectively. Traditional therapeutic approaches often fall short due to their inability to target cancer stem cells and the complex genetic and epigenetic landscape of tumors. In recent years, cancer immunotherapy has revolutionized the field, offering new hope and viable alternatives to conventional treatments. A particularly promising area of research focuses on non-coding RNAs (ncRNAs), especially long non-coding RNAs (lncRNAs), and their role in cancer resistance and the modulation of signaling pathways. To address these challenges, we performed a comprehensive review of recent studies on lncRNAs and their impact on cancer immunotherapy. Our review highlights the crucial roles that lncRNAs play in affecting both innate and adaptive immunity, thereby influencing the outcomes of cancer treatments. Key observations from our review indicate that lncRNAs can modify the tumor immune microenvironment, enhance immune cell infiltration, and regulate cytokine production, all of which contribute to tumor growth and resistance to therapies. These insights suggest that lncRNAs could serve as potential targets for precision medicine, opening up new avenues for developing more effective cancer immunotherapies. By compiling recent research on lncRNAs across various cancers, this review aims to shed light on their mechanisms within the tumor immune microenvironment.

Insights of immune cell heterogeneity, tumor-initiated subtype transformation, drug resistance, treatment and detecting technologies in glioma microenvironment

BACKGROUND

With the gradual understanding of glioma development and the immune microenvironment, many immune cells have been discovered. Despite the growing comprehension of immune cell functions and the clinical application of immunotherapy, the precise roles and characteristics of immune cell subtypes, how glioma induces subtype transformation of immune cells and its impact on glioma progression have yet to be understood.

AIM OF THE REVIEW

In this review, we comprehensively center on the four major immune cells within the glioma microenvironment, particularly neutrophils, macrophages, lymphocytes, myeloid-derived suppressor cells (MDSCs), and other significant immune cells. We discuss (1) immune cell subtype markers, (2) glioma-induced immune cell subtype transformation, (3) the mechanisms of each subtype influencing chemotherapy resistance, (4) therapies targeting immune cells, and (5) immune cell-associated single-cell sequencing. Eventually, we identified the characteristics of immune cell subtypes in glioma, comprehensively summarized the exact mechanism of glioma-induced immune cell subtype transformation, and concluded the progress of single-cell sequencing in exploring immune cell subtypes in glioma.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In conclusion, we have analyzed the mechanism of chemotherapy resistance detailly, and have discovered prospective immunotherapy targets, excavating the potential of novel immunotherapies approach that synergistically combines radiotherapy, chemotherapy, and surgery, thereby paving the way for improved immunotherapeutic strategies against glioma and enhanced patient outcomes.

Impact of obesity‑associated myeloid‑derived suppressor cells on cancer risk and progression (Review)

Obesity is a chronic disease caused by the accumulation of excessive adipose tissue. This disorder is characterized by chronic low‑grade inflammation, which promotes the release of proinflammatory mediators, including cytokines, chemokines and leptin. Simultaneously, chronic inflammation can predispose to cancer development, progression and metastasis. Proinflammatory molecules are involved in the recruitment of specific cell populations in the tumor microenvironment. These cell populations include myeloid‑derived suppressor cells (MDSCs), a heterogeneous, immature myeloid population with immunosuppressive abilities. Obesity‑associated MDSCs have been linked with tumor dissemination, progression and poor clinical outcomes. A comprehensive literature review was conducted to assess the impact of obesity‑associated MDSCs on cancer in both preclinical models and oncological patients with obesity. A secondary objective was to examine the key role that leptin, the most important proinflammatory mediator released by adipocytes, plays in MDSC‑driven immunosuppression Finally, an overview is provided of the different therapeutic approaches available to target MDSCs in the context of obesity‑related cancer.

Cross-talk between leukemic and immune cells at the tumor microenvironment in chronic lymphocytic leukemia: An update review

Chronic lymphocytic leukemia (CLL) is a mature-type B cell malignancy correlated with significant changes and defects in both the innate and adaptive arms of the immune system, together with a high dependency on the tumor microenvironment. Overall, the tumor microenvironment (TME) in CLL provides a supportive niche for leukemic cells to grow and survive, and interactions between CLL cells and the TME can contribute to disease progression and treatment resistance. Therefore, the increasing knowledge of the complicated interaction between immune cells and tumor cells, which is responsible for immune evasion and cancer progression, has provided an opportunity for the development of new therapeutic approaches. In this review, we outline tumor microenvironment-driven contributions to the licensing of immune escape mechanisms in CLL patients.

Dual roles of myeloid-derived suppressor cells in various diseases: a review

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of cells that originate from bone marrow stem cells. In pathological conditions, such as autoimmune disorders, allergies, infections, and cancer, normal myelopoiesis is altered to facilitate the formation of MDSCs. MDSCs were first shown to promote cancer initiation and progression by immunosuppression with the assistance of various chemokines and cytokines. Recently, various studies have demonstrated that MDSCs play two distinct roles depending on the physiological and pathological conditions. MDSCs have protective roles in autoimmune disorders (such as uveoretinitis, multiple sclerosis, rheumatoid arthritis, ankylosing spondylitis, type 1 diabetes, autoimmune hepatitis, inflammatory bowel disease, alopecia areata, and systemic lupus erythematosus), allergies, and organ transplantation. However, they play negative roles in infections and various cancers. Several immunosuppressive functions and mechanisms of MDSCs have been determined in different disease conditions. This review comprehensively discusses the associations between MDSCs and various pathological conditions and briefly describes therapeutic approaches.

IDO1 Inhibitor RY103 Suppresses Trp-GCN2-Mediated Angiogenesis and Counters Immunosuppression in Glioblastoma

Glioma is characterized by strong immunosuppression and excessive angiogenesis. Based on existing reports, it can be speculated that the resistance to anti-angiogenic drug vascular endothelial growth factor A (VEGFA) antibody correlates to the induction of novel immune checkpoint indoleamine 2,3-dioxygenase 1 (IDO1), while IDO1 has also been suggested to be related to tumor angiogenesis. Herein, we aim to clarify the potential role of IDO1 in glioma angiogenesis and the mechanism behind it. Bioinformatic analyses showed that the expressions of IDO1 and angiogenesis markers VEGFA and CD34 were positively correlated and increased with pathological grade in glioma. IDO1-overexpression-derived-tryptophan depletion activated the general control nonderepressible 2 (GCN2) pathway and upregulated VEGFA in glioma cells. The tube formation ability of angiogenesis model cells could be inhibited by IDO1 inhibitors and influenced by the activity and expression of IDO1 in condition medium. A significant increase in serum VEGFA concentration and tumor CD34 expression was observed in IDO1-overexpressing GL261 subcutaneous glioma-bearing mice. IDO1 inhibitor RY103 showed positive anti-tumor efficacy, including the anti-angiogenesis effect and upregulation of natural killer cells in GL261 glioma-bearing mice. As expected, the combination of RY103 and anti-angiogenesis agent sunitinib was proved to be a better therapeutic strategy than either monotherapy.

JAK inhibition enhances checkpoint blockade immunotherapy in patients with Hodgkin lymphoma

Unleashing antitumor T cell activity by checkpoint inhibitor immunotherapy is effective in cancer patients, but clinical responses are limited. Cytokine signaling through the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway correlates with checkpoint immunotherapy resistance. We report a phase I clinical trial of the JAK inhibitor ruxolitinib with anti-PD-1 antibody nivolumab in Hodgkin lymphoma patients relapsed or refractory following checkpoint inhibitor immunotherapy. The combination yielded a best overall response rate of 53% (10/19). Ruxolitinib significantly reduced neutrophil-to-lymphocyte ratios and percentages of myeloid suppressor cells but increased numbers of cytokine-producing T cells. Ruxolitinib rescued the function of exhausted T cells and enhanced the efficacy of immune checkpoint blockade in preclinical solid tumor and lymphoma models. This synergy was characterized by a switch from suppressive to immunostimulatory myeloid cells, which enhanced T cell division.

Engineered CD147-Deficient THP-1 Impairs Monocytic Myeloid-Derived Suppressor Cell Differentiation but Maintains Antibody-Dependent Cellular Phagocytosis Function for Jurkat T-ALL Cells with Humanized Anti-CD147 Antibody

CD147 is upregulated in cancers, including aggressive T-ALL. Traditional treatments for T-ALL often entail severe side effects and the risk of relapse, highlighting the need for more efficacious therapies. ADCP contributes to the antitumor response by enhancing the ability of phagocytic cells to engulf cancer cells upon antibody binding. We aimed to engineer CD147KO THP-1 cells and evaluated their differentiation properties compared to the wild type. A humanized anti-CD147 antibody, HuM6-1B9, was also constructed for investing the phagocytic function of CD147KO THP-1 cells mediated by HuM6-1B9 in the phagocytosis of Jurkat T cells. The CD147KO THP-1 was generated by CRISPR/Cas9 and maintained polarization profiles. HuM6-1B9 was produced in CHO-K1 cells and effectively bound to CD147 with high binding affinity (KD: 2.05 ± 0.30 × 10-9 M). Additionally, HuM6-1B9 enhanced the phagocytosis of Jurkat T cells by CD147KO THP-1-derived LPS-activated macrophages (M-LPS), without self-ADCP. The formation of THP-1-derived mMDSC was limited in CD147KO THP-1 cells, highlighting the significant impact of CD147 deletion. Maintaining expression markers and phagocytic function in CD147KO THP-1 macrophages supports future engineering and the application of induced pluripotent stem cell-derived macrophages. The combination of HuM6-1B9 and CD147KO monocyte-derived macrophages holds promise as an alternative strategy for T-ALL.

RNAi mediated silencing of STAT3/PD-L1 in tumor-associated immune cells induces robust anti-tumor effects in immunotherapy resistant tumors

Malignant tumors are often associated with an immunosuppressive tumor microenvironment (TME), rendering most of them resistant to standard-of-care immune checkpoint inhibitors (CPIs). Signal transducer and activator of transcription 3 (STAT3), a ubiquitously expressed transcription factor, has well-defined immunosuppressive functions in several leukocyte populations within the TME. Since the STAT3 protein has been challenging to target using conventional pharmaceutical modalities, we investigated the feasibility of applying systemically delivered RNA interference (RNAi) agents to silence its mRNA directly in tumor-associated immune cells. In preclinical rodent tumor models, chemically stabilized acylated small interfering RNAs (siRNAs) selectively silenced Stat3 mRNA in multiple relevant cell types, reduced STAT3 protein levels, and increased cytotoxic T cell infiltration. In a murine model of CPI-resistant pancreatic cancer, RNAi-mediated Stat3 silencing resulted in tumor growth inhibition, which was further enhanced in combination with CPIs. To further exemplify the utility of RNAi for cancer immunotherapy, this technology was used to silence Cd274, the gene encoding the immune checkpoint protein programmed death-ligand 1 (PD-L1). Interestingly, silencing of Cd274 was effective in tumor models that are resistant to PD-L1 antibody therapy. These data represent the first demonstration of systemic delivery of RNAi agents to the TME and suggest applying this technology for immuno-oncology applications.