Myeloid-derived suppressor cells in cancer and cancer therapy

Immune-based strategies for the treatment of biofilm infections

Biofilms are bacterial communities surrounded by a polymeric matrix that can form on implanted materials and biotic surfaces, resulting in chronic infection that is recalcitrant to immune- and antibiotic-mediated clearance. Therefore, biofilm infections present a substantial clinical challenge, as treatment often involves additional surgical interventions to remove the biofilm nidus, prolonged antimicrobial therapy to clear residual bacteria, and considerable risk of treatment failure or infection recurrence. These factors, combined with progressive increases in antimicrobial resistance, highlight the need for alternative therapeutic strategies to circumvent undue morbidity, mortality, and resource strain on the healthcare system resulting from biofilm infections. One promising option is reprogramming dysfunctional immune responses elicited by biofilm. Here, we review the literature describing immune responses to biofilm infection with a focus on targets or strategies ripe for clinical translation. This represents a complex and dynamic challenge, with context-dependent host-pathogen interactions that differ across infection models, microenvironments, and individuals. Nevertheless, consistencies among these variables exist, which could facilitate the development of immune-based strategies for the future treatment of biofilm infections.

Multifunctional nanoparticle-mediated targeting of metabolic reprogramming and DNA damage response pathways to treat drug-resistant triple-negative breast cancer

Multi-drug resistance and immunosuppressive triple-negative breast cancer (TNBC) is triggered by the Warburg effect, which promotes homologous recombination repair (HRR) and upregulates expression of P-glycoprotein (P-gp), in turn preventing DNA damage from chemotherapy and creating an immunosuppressive microenvironment. It is therefore of clinical relevance to develop an effective delivery system that targets metabolic reprogramming and DNA damage response pathways for the treatment of drug-resistant TNBC. Herein, a P-gp-inhibiting and GSH-responsive multifunctional drug carrier targeting integrin αvβ3 was synthesised for the delivery of Lonidamine-prodrug (M1, glycolysis inhibitor) and Senaparib (Se, Poly [ADP-ribose] polymerase inhibitor). The nanodrug delivery system (iPR@M1/Se nanoparticles) exhibit effective tumour penetration and P-gp inhibition, effectively inducing DNA damage and apoptosis in Olaparib-resistant TNBC cells in vitro, as well as a higher tumour inhibitory rate compared with that of Se (81.82 % ± 2.31 % vs 43.91 % ± 4.65 %) in vivo. Mechanistically, iPR@M1/Se nanoparticles not only reshaped the immunosuppressive microenvironment resulting from tumour glycolysis, but also downregulated the expression of HRR-related protein, fostering the cytoplasmic accumulation of DNA damage fragments, which induced activation of the cyclic GMP-AMP synthase (cGAS)/stimulator of interferon gene (STING) pathway. Experimental results show that iPR@M1/Se nanoparticles effectively promote dendritic cell maturation and T lymphocyte activation, which elicits long-term immune memory responses, and prevents tumour recurrence and lung metastasis. Therefore, these multifunctional nanoparticles have great potential and provide a clinically relevant and valuable option for Olaparib-resistant TNBC.

Osteopontin promotes tumor microenvironment remodeling and therapy resistance

Osteopontin (OPN) is a multifunctional secretory protein which can be expressed and secreted by a variety of tumor cells and immune cells. Tumor microenvironment remodeling provides favorable conditions for tumor progression, immune escape and therapy resistance. As a bridge molecule in crosstalk between tumor cells and tumor microenvironment, OPN can not only come from tumor cells to regulate the functions of various immune cells, promoting the formation of immunosuppressive environment, but also can be secreted by immune cells to act on tumor cells, leading to tumor progression, thus constructing a positive feedback regulatory network. Here, we summarize the molecular structure, source and receptor of OPN, and clarify the mechanism of OPN on tumor-associated macrophages, dendritic cells, myeloid-derived suppressor cells, tumor progression and therapy resistance to comprehensively understand the great potential of OPN as a tumor biomarker and therapeutic target.

Therapeutic targeting of the p300/CBP bromodomain enhances the efficacy of immune checkpoint blockade therapy

Blockade of immune checkpoints, such as programmed death-ligand 1 (PD-L1), has shown promise in cancer treatment; however, clinical response remains limited in many cancer types. Our previous research demonstrated that p300/CBP mediates the acetylation of the PD-L1 promoter, regulating PD-L1 expression. In this study, we further investigated the role of the p300/CBP bromodomain in regulating PD-L1 expression using CCS1477, a selective bromodomain inhibitor developed by our team. We found that the p300/CBP bromodomain is essential for H3K27 acetylation at PD-L1 enhancers. Inhibiting this modification significantly reduced enhancer activity and PD-L1 transcription, including exosomal PD-L1, which has been implicated as key contributors to resistance against PD-L1 blockade therapy in various cancers. Furthermore, CCS1477 treatment resulted in a marked reduction of myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment (TME) by inhibiting key cytokines such as IL6, CSF1, and CSF2, which are crucial for MDSC differentiation and recruitment. By reducing PD-L1 expression and modulating the immunosuppressive TME, CCS1477 creates a more favorable environment for tumor-infiltrating lymphocytes, significantly enhancing the efficacy of immune checkpoint blockade (ICB) therapy. Notably, these effects were observed in both prostate cancer and melanoma models, underscoring the broad therapeutic potential of p300/CBP bromodomain inhibition in improving ICB outcomes.

Inhibiting glycolysis facilitated checkpoint blockade therapy for triple-negative breast cancer

Cancer cells are characterized by their altered energy metabolism. A hallmark of cancer metabolism is aerobic glycolysis, also called the Warburg effect. Hexokinase 2 (HK2), a crucial glycolytic enzyme converting glucose to glucose-6-phosphate, has been identified as a central player in the Warburg effect. Deletion of HK2 decreases cancer cell proliferation in animal models without explicit side effects, suggesting that targeting HK2 is a promising strategy for cancer therapy. In this study, we discovered a correlation between HK2 and the tumor immune response in triple-negative breast cancer. Inhibition of HK2 led to a reduction in G-CSF expression in 4T1 cells and a decrease in the development of myeloid-derived suppressor cells which, in turn, enhanced T cell immunity and prolonged the survival of 4T1 tumor-bearing mice. Furthermore, the HK2 inhibitor 3-BrPA improved the therapeutic efficacy of anti-PD-L1 therapy in 4T1 tumor-bearing mouse models. This study highlights the potential of glycolysis-targeting interventions as a novel treatment strategy, which can be combined with immunotherapy for the treatment of triple-negative breast cancer.

F-box protein 22: A prognostic biomarker for colon cancer associated with immune infiltration and chemotherapy resistance

BACKGROUND

Colon cancer represents a significant malignant neoplasm within the digestive system, characterized by a high incidence rate and substantial disease burden. The F-box protein 22 (FBXO22) plays a role in forming a specific type of ubiquitin ligase subunit, which is expressed abnormally in various malignant neoplasms and shows a notable relationship with prognosis in patients with cancer. Nevertheless, the function of FBXO22 in the context of colon cancer remains inadequately elucidated.

AIM

To explore the role of FBXO22 in colon cancer by examining FBXO22 expression patterns and analyzing how the protein affects the prognosis in patients who have undergone surgery.

METHODS

Samples of cancerous and nearby normal tissues from patients with colon cancer were gathered, along with pertinent clinical data. Expression levels of the FBXO22 gene in both cancerous and paracancerous tissues were assessed through immunohistochemistry. The median H score served as a criterion for categorizing FBXO22 gene expression into high and low levels in cancerous tissues, and the relationship between these expression levels and various pathologic characteristics of patients, such as age, sex, and clinical stage, was analyzed. Colon cancer cell lines HCT116 and DLD-1 were used and divided into three groups: A blank control group, a negative control group, and a si-FBXO22 group. FBXO22 gene mRNA and protein expression were measured 24 hours post-transfection using real-time fluorescence quantitative polymerase chain reaction and western blotting. The proliferation capabilities of the cells in each group were assessed using the Cell Counting Kit-8 assay and 5-ethynyl-2'-deoxyuridine assay, while cellular migration and invasion abilities were evaluated using scratch healing and Transwell assays. Various online platforms, including the Timer Immune Estimation Resource, were used to analyze pan-cancer expression, promoter methylation levels, and mutation frequencies of the FBXO22 gene in colon cancer patients. Additionally, the correlation between FBXO22 gene expression, patient prognosis, immune cell infiltration, and the expression of immune molecules in the colon cancer microenvironment was investigated. The relationship between FBXO22 gene expression and chemotherapy resistance, along with the potential mechanisms of action of the FBXO22 gene, were analyzed using The Cancer Genome Atlas dataset and the Genomics of Drug Sensitivity in Cancer drug training set via R software.

RESULTS

Compared with normal colonic tissues, the FBXO22 gene was highly expressed in colon cancer tissues. Post-operative patients with colon cancer elevated FBXO22 reduced survival and exhibited resistance to various chemotherapeutic agents. FBXO22 expression suppresses the infiltration of anti-tumor immune cells. In vitro, FBXO22 knockdown inhibited the proliferation and migration of colon cancer cells.

CONCLUSION

The FBXO22 gene is a biomarker of poor prognosis in patients with colon cancer and has potential as a target for immunotherapy and overcoming chemotherapy resistance.

Microneedle-based nanodrugs for tumor immunotherapy

Microneedles have emerged as a promising and effective method for delivering therapeutic drugs and immunobiologics to treat various diseases. It is widely recognized that immune therapy has limited efficacy in solid tumors due to physical barriers and the immunosuppressive tumor microenvironment. Microneedle-based nanodrugs (NDMNs) offer a novel approach to overcome these limitations. These tiny needles are designed to load a variety of inorganic and organic nanoparticles, antigen vaccines, gene drugs, oncolytic viruses, and more. Utilizing microneedle arrays, NDMNs can effectively penetrate the skin barrier, delivering drugs precisely to the tumor site or immunoactive regions within the skin. Additionally, by designing and optimizing the microneedle structure, shape, and functionality, NDMNs enable precise drug release and efficient penetration, thereby enhancing the efficacy of tumor immunotherapy. In this review, we comprehensively discuss the pivotal role of NDMNs in cancer immunotherapy, summarizing innovative microneedle design strategies, mechanisms of immune activation, and delivery strategies of various nanodrugs. Furthermore, we explore the current clinical realities, limitations, and future prospects of NDMNs in tumor immunotherapy.

Targeting myeloid cells for hematological malignancies: the present and future

Hematological malignancies are a diverse group of cancers that originate in the blood and bone marrow and are characterized by the abnormal proliferation and differentiation of hematopoietic cells. Myeloid blasts, which are derived from normal myeloid progenitors, play a central role in these diseases by disrupting hematopoiesis and driving disease progression. In addition, other myeloid cells, including tumor-associated macrophages and myeloid-derived suppressor cells, adapt dynamically to the tumor microenvironment, where they can promote immune evasion and resistance to treatment. This review explores the unique characteristics and pathogenic mechanisms of myeloid blasts, the immunosuppressive roles of myeloid cells, and their complex interactions within the TME. Furthermore, we highlight emerging therapeutic approaches targeting myeloid cells, focusing on strategies to reprogram their functions, inhibit their suppressive effects, or eliminate pathological populations altogether, as well as the latest preclinical and clinical trials advancing these approaches. By integrating insights from these studies, we aim to provide a comprehensive understanding of the roles of myeloid cells in hematological malignancies and their potential as therapeutic targets.

Neural crest-associated gene FOXD1 induces an immunosuppressive microenvironment by regulating myeloid-derived suppressor cells in melanoma

BACKGROUND

Neural crest-associated genes play pivotal roles in tumor initiation, progression, and the intricate dynamics of the tumor microenvironment (TME). Myeloid-derived suppressor cells (MDSC) within the TME are important in dampening T cell activity and contributing to resistance against immunotherapeutic interventions. The neural crest-associated gene Forkhead Box D1 (FOXD1) has been identified as an oncogenic factor that induces melanoma dedifferentiation and progression. However, the underlying mechanisms and the impact of FOXD1 on the antitumor immune response remain unclear.

METHODS

To investigate the impacts of FOXD1 on the melanoma microenvironment, we analyzed publicly available datasets from multiple platforms, including TNMplot, TIMER2.0, etc. In addition, FOXD1 was overexpressed (OE) or knocked down in melanoma cells to identify its biological functions in vitro and in vivo. Flow cytometry and arginase activity assay were used to analyze the phenotype and function of MDSC. Western blot, reverse transcription-PCR, or ELISA assays were employed to analyze the expression of FOXD1 and its downstream effectors. In vivo experiments were conducted to investigate the role of FOXD1 in melanoma progression and the influence on MDSC accumulation within the TME.

RESULTS

We demonstrate that increased FOXD1 levels inversely correlated with melanoma responsiveness to immunotherapy. Ex-vivo analyses unveiled that monocytes, exposed to conditioned medium from FOXD1-OE melanoma cells, effectively suppressed T cell proliferation and upregulated the expression of programmed death-ligand 1 (PD-L1) and other immunosuppressive factors. FOXD1 was identified as a direct regulator of interleukin 6 (IL6) expression, which is pivotal for MDSC induction. Blocking IL6 reversed MDSC-associated immunosuppression. Additionally, miR-581, a potential negative regulator of FOXD1, attenuated the impact of FOXD1 on IL6 expression and MDSC differentiation. In vivo experiments demonstrated that tumors derived from FOXD1 OE melanoma cells contained a significantly higher frequency of PD-L1+ MDSC compared with controls, while FOXD1 knockdown resulted in reduced tumor growth and diminished MDSC accumulation.

CONCLUSION

Our study elucidated a novel function of FOXD1 in melanoma pathogenesis, highlighting its role in orchestrating the immunosuppressive TME by promoting the generation of MDSC via IL6 upregulation.

Targeting DKK3 to remodel tumor immune microenvironment and enhance cancer immunotherapy

Cancer immunotherapy such as immune checkpoint blockade (ICB) therapy has made important breakthroughs in cancer treatment, however, currently only parts of cancer patients benefit from ICB therapy. The suppressive tumor immune microenvironment (TIME) impedes the treatment response of immunotherapy, indicating the necessity to explore new treatment targets. Here, we reported a new potential immunotherapeutic target, Dickkopf-3 (DKK3), for cancer treatment. DKK3 expression is up-regulated in the tumors from multiple cancer types, and high DKK3 expression is associated with worse survival outcome across different cancers. We observed that DKK3 directly inhibits the activation of CD8+ T cells and the Th1 differentiation of CD4+ T cells ex vivo. Also, by establishing four different mouse cancer models, we found that DKK3 blockade triggers effective anti-tumor effects and improve the survival of tumor-bearing mice in vivo. DKK3 blockade also remodels the suppressive TIME of different cancer types, including the increased infiltration of CD8+ T cells, IFN-γ+CD8+ T cells, Th1 cells, and decreased infiltration of M2 macrophages and MDSCs in the TIME. Moreover, we found that combined blockade of DKK3 and PD-1 induces synergistic tumor-control effect in our mouse cancer model. Therefore, our study reveals the impact of DKK3 in the TIME and cancer progression, which suggests that DKK3 is a novel and promising immunotherapeutic target for enhanced cancer immunotherapy.

Gemcitabine: immunomodulatory or immunosuppressive role in the tumor microenvironment

Gemcitabine (GEM), a nucleoside analog chemotherapy agent, has been widely used in the treatment of various cancers. In recent years, there has been growing interest in understanding the immunomodulatory or immunosuppressive effects of GEM. The immunomodulatory roles of GEM could influence the anti-tumor immune responses via several mechanisms, such as modulation of antigen presentation, cytokine production, and immune cell population. Furthermore, there is evidence that GEM enhances the therapeutic efficacy of immunotherapies, including oncolytic viruses, immune checkpoint inhibitors, CAR T-cells, and therapeutic vaccines. On the other hand, accumulating evidence also proposed that GEM may act as an immunosuppressive agent within the tumor microenvironment, resulting in immune evasion of tumor cells and tumor growth. These paradoxical roles of GEM in modifying immune responses highlight the complexity of GEM interaction with immune cells and responses within the tumor microenvironment. This review aims to provide an overview of the immunomodulatory and immunosuppressive effects of GEM within the tumor microenvironment and how GEM affects the efficacy of cancer immunotherapy.

Mapping immunotherapy potential: spatial transcriptomics in the unraveling of tumor-immune microenvironments in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) often exhibits poor response rates to immune checkpoint inhibitor (ICI) therapies, largely owing to the intricate composition and spatial organization of immune cells within the tumor-immune microenvironment (TIME). The diversity of immune cell populations, their spatial relationships, and dynamic interactions significantly influence the immunosuppressive nature of the TIME, thereby limiting the efficacy of immunotherapy. To address these challenges and enhance the therapeutic potential of ICIs in HNSCC, a comprehensive analysis of the TIME is essential. Spatial transcriptomics (ST), a cutting-edge technology, enables high-resolution mapping of gene expression within the spatial context of the tumor, providing critical insights into the functional roles and interactions of immune cells in the TIME. This review highlights the importance of ST in uncovering the complexities of the TIME in HNSCC and proposes strategies for leveraging these insights to develop more effective immunotherapeutic approaches. By integrating spatial and molecular information, this review aims to pave the way for personalized and precision-based treatments in HNSCC, ultimately improving patient outcomes.

Where lung cancer and tuberculosis intersect: recent advances

Lung cancer (LC) and tuberculosis (TB) represent two major global public health issues. Prior evidence has suggested a link between TB infection and an increased risk of LC. As advancements in LC treatment have led to extended survival rates for LC patients, the co-occurrence of TB and LC has grown more prevalent and poses novel clinical challenges. The intricate molecular mechanisms connecting TB and LC are closely intertwined and many issues remain to be addressed. This review focuses on resemblance between the immunosuppression in tumor and granuloma microenvironments, exploring immunometabolism, cell plasticity, inflammatory signaling pathways, microbiomics, and up-to-date information derived from spatial multi-omics between TB and LC. Furthermore, we outline immunization-related molecular mechanisms underlying these two diseases and propose future research directions. By discussing recent advances and potential targets, this review aims to establish a foundation for developing future therapeutic strategies targeting LC with concurrent TB infection.

The role of the tumor microenvironment in HNSCC resistance and targeted therapy

The prognosis for head and neck squamous cell carcinoma (HNSCC) remains unfavorable, primarily due to significant therapeutic resistance and the absence effective interventions. A major obstacle in cancer treatment is the persistent resistance of cancer cells to a variety of therapeutic modalities. The tumor microenvironment (TME) which includes encompasses all non-malignant components and their metabolites within the tumor tissue, plays a crucial role in this context. The distinct characteristics of the HNSCC TME facilitate tumor growth, invasion, metastasis, and resistance to treatment. This review provides a comprehensive overview of the HNSCC TME components, with a particular focus on tumor-associated macrophages (TAMs), regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSCs), cancer-associated fibroblasts (CAFs), the extracellular matrix, reprogrammed metabolic processes, and metabolic products. It elucidates their contributions to modulating resistance to chemotherapy, radiotherapy, targeted therapy, and immunotherapy in HNSCC, and explores novel therapeutic strategies targeting the TME for HNSCC management.

Evaluation of ImmunoPET in the efficacy and prognosis of immunotherapy for lung cancer

Advances in immune oncology have established immunotherapy as the first-line standard treatment for lung cancer; however, its efficacy remains limited to a subset of patients. Developing predictive biomarkers within the tumor microenvironment (TME) to assess the efficacy and prognosis of immunotherapy can enhance drug development and treatment strategies. Immuno-positron emission tomography (ImmunoPET) non-invasively visualizes the biological distribution of key targets in the TME using highly specific, radiolabeled tracers. PET imaging of the TME can serve as a reliable biomarker for predicting and monitoring responses to immune therapy, complementing existing immunohistochemical techniques. This review will focus on the development of ImmunoPET biomarkers, as well as the application of corresponding tracers and radionuclides in lung cancer. We will focus on available clinical tracers and those under development, outlining each TME target and its clinical validation for tumor immunotherapy efficacy and prognosis, while discussing the latest advances that may enhance ImmunoPET in future.

Heterogeneity of modulatory immune microenvironment in bladder cancer

Urinary bladder cancer (UBC) is the ninth most common cancer worldwide. The intra-tumor heterogeneity of the UBC microenvironment explains the variances in response to therapy among patients. Tumor immune microenvironment (TIME) is based on the balance between anti-tumor and pro-tumorigenic immunity that eventually determines the tumor fate. This review addresses the recent insights of the cytokines, immune checkpoints, receptors, enzymes, proteins, RNAs, cancer stem cells (CSCs), tissue-resident cells, growth factors, epithelial-mesenchymal transition, microbiological cofactor, and paracrine action of cancer cells that mutually cross-talk within the TIME. In-depth balance and alteration of these factors influence the TIME and the overall tumor progression. This, in turn, highlights the prospects of the new era of manipulating these co-factors for improving the diagnosis, prognosis, and treatment of UBC. CONCLUSION: The heterogenic architecture of the TIME orchestrates the fate of the tumor. Nevertheless, recognizing the mutual cross-talk between these key players seems useful in prognostic and therapeutic approaches.

Recent developments in myeloid immune modulation in cancer therapy

Myeloid cells play a crucial dual role in cancer progression and response to therapy, promoting tumor growth, enabling immune suppression, and contributing to metastatic spread. The ability of these cells to modulate the immune system has made them attractive targets for therapeutic strategies aimed at shifting their function from tumor promotion to fostering antitumor immunity. Therapeutic approaches targeting myeloid cells focus on modifying their numbers, genetics, metabolism, and interactions within the tumor microenvironment. These strategies aim to reverse their suppressive functions and redirect them to support antitumor immune responses by inhibiting immunosuppressive pathways, targeting specific receptors, and promoting their differentiation into less immunosuppressive phenotypes. Here, we discuss recent approaches to clinically target tumor myeloid cells, focusing on reprogramming myeloid cells to promote antitumor immunity.

Key immune cells and their crosstalk in the tumor microenvironment of bladder cancer: insights for innovative therapies

Bladder cancer (BC) is a heterogeneous disease associated with high mortality if not diagnosed early. BC is classified into non-muscle-invasive BC (NMIBC) and muscle-invasive BC (MIBC), with MIBC linked to poor systemic therapy response and high recurrence rates. Current treatments include transurethral resection with Bacillus Calmette-Guérin (BCG) therapy for NMIBC and radical cystectomy with chemotherapy and/or immunotherapy for MIBC. The tumor microenvironment (TME) plays a critical role in cancer progression, metastasis, and therapeutic efficacy. A comprehensive understanding of the TME's complex interactions holds substantial translational significance for developing innovative treatments. The TME can contribute to therapeutic resistance, particularly in immune checkpoint inhibitor (ICI) therapies, where resistance arises from tumor-intrinsic changes or extrinsic TME factors. Recent advancements in immunotherapy highlight the importance of translational research to address these challenges. Strategies to overcome resistance focus on remodeling the TME to transform immunologically "cold" tumors, which lack immune cell infiltration, into "hot" tumors that respond better to immunotherapy. These strategies involve disrupting cancer-microenvironment interactions, inhibiting angiogenesis, and modulating immune components to enhance anti-tumor responses. Key mechanisms include cytokine involvement [e.g., interleukin-6 (IL-6)], phenotypic alterations in macrophages and natural killer (NK) cells, and the plasticity of cancer-associated fibroblasts (CAFs). Identifying potential therapeutic targets within the TME can improve outcomes for MIBC patients. This review emphasizes the TME's complexity and its impact on guiding novel therapeutic approaches, offering hope for better survival in MIBC.

Overcoming immunotherapy resistance in glioblastoma: challenges and emerging strategies

Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults, characterized by rapid proliferation, extensive infiltration, and significant intratumoral heterogeneity. Despite advancements in conventional treatments, including surgery, radiotherapy, and chemotherapy, the prognosis for GBM patients remains poor, with a median survival of approximately 15 months. Immunotherapy has emerged as a promising alternative; however, the unique biological and immunological features, including its immunosuppressive tumor microenvironment (TME) and low mutational burden, render it resistant to many immunotherapeutic strategies. This review explores the key challenges in GBM immunotherapy, focusing on immune evasion mechanisms, the blood-brain barrier (BBB), and the TME. Immune checkpoint inhibitors and CAR-T cells have shown promise in preclinical models but have limited clinical success due to antigen heterogeneity, immune cell exhaustion, and impaired trafficking across the BBB. Emerging strategies, including dual-targeting CAR-T cells, engineered immune cells secreting therapeutic molecules, and advanced delivery systems to overcome the BBB, show potential for enhancing treatment efficacy. Addressing these challenges is crucial for improving GBM immunotherapy outcomes.

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.

Multiomic analysis identifies suppressive myeloid cell populations in human TB granulomas

Tuberculosis (TB) remains a major global health challenge, particularly in the context of multidrug-resistant (MDR) Mycobacterium tuberculosis (Mtb). Host-directed therapies (HDTs) have been proposed as adjunctive therapy to enhance immune control of infection. Recently, one such HDT, pharmacologic modulation of myeloid-derived suppressor cells (MDSCs), has been proposed to treat MDR-TB. While MDSCs have been well characterized in cancer, their role in TB pathogenesis remains unclear. To investigate whether MDSCs or other myeloid suppressor populations contribute to TB granuloma microenvironments (GME), we performed spatial transcriptional profiling and single-cell immunophenotyping on eighty-four granulomas in lung specimens from three individuals with active disease. Granulomas were histologically classified based on H&E staining, and transcriptional signatures were compared across regions of interest (ROIs) at different states of granuloma maturation. Our analysis revealed that immune suppression within granuloma was not primarily driven by classical MDSCs but rather by multiple myeloid cell subsets, including dendritic cells expressing indoleamine 2,3 dioxygenase-1 expressing (IDO1+ DCs). IDO1+ DCs were the most frequently observed suppressive myeloid cells, particularly in cellular regions, and their spatial proximity to activated T cells suggested localized immunosuppression. Importantly, granulomas at different stages contained distinct proportions of suppressor myeloid cells, with necrotic and cellular regions showing different myeloid phenotypes that may influence granuloma progression. Gene set enrichment analysis (GSEA) further indicated that elevated IDO1 expression was associated with a complex immune response that balanced suppressive signaling, immune activation, and cellular metabolism. These findings suggest that classical MDSCs, as defined in tumor microenvironments, likely play a minor role in TB, whereas IDO1+ DCs may be key regulators of immune suppression in granulomas influencing local Mtb control in infected lung. A deeper understanding of the role of IDO1+ suppressive myeloid cells in TB granulomas is essential to assessing their potential as therapeutic targets in TB treatment.

Selinexor's Immunomodulatory Impact in Advancing Multiple Myeloma Treatment

Despite the major advancements in the repertoire for multiple myeloma (MM) treatment, this disease remains a chronically progressive plasma cell malignancy. Drug resistance and high relapse rates complicate the extended treatment strategies. However, the tumor microenvironment (TME) in MM is decisive for the success of a therapy or relapse. Aiming to improve the outcome of relapsed and refractory MM patients, Selinexor has entered the drug arsenal of myeloma therapy through the implementation of a novel therapeutic approach by selectively inhibiting the nuclear export receptor Exportin-1 (XPO1). Selinexor leads to the inactivation of cancer-related proteins and induces apoptosis by disrupting the nucleocytoplasmic flow in myeloma cells. While this drug is selectively cytotoxic to neoplastic cells, Selinexor's immunomodulatory impact on the TME is currently being investigated. The aim of this review was to elucidate Selinexor's capacity to influence the cell interaction network of the TME from an immunological perspective. Deciphering the complex interplay of highly plastic immune cells provides a contribution to the molecular-biological exploration of disease initiation and progression in MM. Unraveling the novel therapeutic targets of the immunological TME and evaluating the advanced immunotherapeutic regimens implementing Selinexor will shape the future directions of immune-oncotherapy in MM.

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.

Digging Through the Complexities of Immunological Approaches in Emerging Osteosarcoma Therapeutics: A Comprehensive Narrative Review with Updated Clinical Trials

Osteosarcoma (OS) is the predominant mesenchymal primary malignant bone tumor in oncology and pathology, impacting a wide age range from adolescents to older adults. It frequently advances to lung metastasis, ultimately resulting in the mortality of OS patients. The precise pathological pathways responsible for OS progression and dissemination are not fully understood due to its heterogeneity. The integration of surgery with neoadjuvant and postoperative chemotherapy has significantly increased the 5-year survival rate to more than 70% for patients with localized OS tumors. However, about 30% of patients experience local recurrence and/or metastasis. Hence, there is a requirement for innovative therapeutic approaches to address the limitations of traditional treatments. Immunotherapy has garnered increasing attention as a promising avenue for tumors resistant to standard therapies, including OS, despite the underlying mechanisms of disease progression and dissemination remaining not well elucidated. Immunotherapy may not have been suitable for use in patients with OS because of the tumor's immunosuppressive microenvironment and limited immunogenicity. Nevertheless, there are immune-based treatments now being developed for clinical use, such as bispecific antibodies, chimeric antigen receptor T cells, and immune checkpoint inhibitors. Also, additional immunotherapy techniques including cytokines, vaccines, and modified-Natural Killer (NK) cells/macrophages are in the early phases of research but will certainly be popular subjects in the nearest future. Our goal in writing this review was to spark new lines of inquiry into OS immunotherapy by summarizing the findings from both preclinical and current clinical studies examining different approaches.

Harnessing myeloid cells in cancer

Cancer-associated myeloid cells due to their plasticity play dual roles in both promoting and inhibiting tumor progression. Myeloid cells with immunosuppressive properties play a critical role in anti-cancer immune regulation. Cells of different origin, such as tumor associated macrophages (TAMs), tumor associated neutrophils (TANs), myeloid derived suppressor cells (also called MDSCs) and eosinophils are often expanded in cancer patients and significantly influence their survival, but also the outcome of anti-cancer therapies. For this reason, the variety of preclinical and clinical studies to modulate the activity of these cells have been conducted, however without successful outcome to date. In this review, pro-tumor activity of myeloid cells, myeloid cell-specific therapeutic targets, in vivo studies on myeloid cell re-polarization and the impact of myeloid cells on immunotherapies/genetic engineering are addressed. This paper also summarizes ongoing clinical trials and the concept of chimeric antigen receptor macrophage (CAR-M) therapies, and suggests future research perspectives, offering new opportunities in the development of novel clinical treatment strategies.

Cell-intrinsic PD-L1 signaling drives immunosuppression by myeloid-derived suppressor cells through IL-6/Jak/Stat3 in PD-L1-high lung cancer

BACKGROUND

Some patients with non-small-cell lung cancer (NSCLC) benefit from immune checkpoint inhibitors (ICIs) despite programmed death-ligand 1 (PD-L1) expression. To address the mechanism of ICI resistance in PD-L1-positive NSCLC, we investigated the role of tumor-cell-intrinsic function of PD-L1 in interleukin (IL)-6-mediated immunosuppression.

METHODS

Cohorts of NSCLC patients treated with ICI and public datasets were analyzed. PD-L1-overexpressing and PD-L1-knockdown NSCLC cells were submitted to RNA-seq, in vitro analyses, chromatin immunoprecipitation-qPCR, CUT&Tag, and biochemical assays. Human myeloid-derived suppressor cells (MDSCs) sorted from peripheral blood mononuclear cells were co-cultured with NSCLC cells and then assessed for their immunosuppressive activity on T-cells. Mouse Lewis lung carcinoma (LLC) cells with PD-L1 overexpression or knockdown were subcutaneously injected into wild-type or PD-1-knockout C57BL/6 mice in the presence of IL-6 and/or PD-1 blockade.

RESULTS

In the ICI cohort with RNA-seq data, the IL-6/Jak/Stat3 pathway was enriched, and IL-6 expression was higher in patients with PD-L1-high NSCLCs who did not respond to ICIs. In another cohort, a higher baseline serum IL-6 level was associated with poor clinical outcomes after ICI therapy. IL-6 expression and the IL-6/Jak/Stat3 pathway were enhanced in PD-L1-high NSCLCs in the ICI cohorts and The Cancer Genome Atlas analysis. IL-6 expression correlated positively with tumor-infiltrating MDSCs in NSCLCs. In NSCLC cells, PD-L1 activated Jak2/Stat3 signaling by binding to and inhibiting protein tyrosine phosphatase 1B. PD-L1 also bound to p-Stat3 in the nucleus, thus promoting the activity of p-Stat3 in the transcription of several cytokines (IL-6, TGF-β, TNF-α, IL-1β) and chemokines. PD-L1-overexpressing NSCLC cells enhanced the migration and immunosuppressive activity of human MDSCs in vitro, mediated by IL-6 and CXCL1. In both wild-type and PD-1-knockout mice, PD-L1-overexpressing LLC tumors were infiltrated by increased MDSCs with high immunosuppressive function, increased Tregs, and decreased granzyme B+ or IFNγ+ CD8 T-cells. These responses were mediated by IL-6 secreted from PD-L1-overexpressing tumor cells. Combined blockade of PD-1 and IL-6 was effective in tumor control and decreased MDSCs while increasing granzyme B+ or IFNγ+ CD8 T-cells.

CONCLUSIONS

The tumor-cell-intrinsic function of PD-L1 drives immunosuppression and tumor progression through the PD-L1/Jak/Stat3/IL-6/MDSC axis. This pathway represents a potential therapeutic target to improve ICI efficacy in PD-L1-high NSCLC.

Tumor-derived extracellular vesicles: key drivers of immunomodulation in breast cancer

Breast cancer (BC) remains a significant global health challenge characterized by its heterogeneity and treatment complexities. Extracellular vesicles (EVs) are small membranous particles released by cells, facilitating intercellular communication by transporting bioactive molecules such as proteins, lipids, and nucleic acids. Tumor-derived EVs have emerged as pivotal regulators in the tumor microenvironment (TME) and drivers of BC progression. These EVs carry diverse cargoes of bioactive molecules, influencing critical processes such as immune modulation, angiogenesis, and metastasis. By altering the behaviors of immune cells including macrophages, dendritic cells, and T cells, tumor-derived EVs contribute to immune evasion and tumor growth. Furthermore, Tumor-derived EVs play a role in mediating drug resistance, impacting the effectiveness of therapeutic interventions. Understanding the multifaceted roles of BC tumor-derived EVs is essential for the development of innovative therapeutic strategies. Targeting pathways mediated by EVs holds promise for enhancing the efficacy of cancer treatments and improving patient outcomes. This comprehensive review provides insights into the intricate interactions of tumor-derived EVs in immune modulation and BC progression, highlighting potential therapeutic targets and avenues for novel cancer therapies.

Effect of Extracellular Vesicles Derived From Tumor Cells on Immune Evasion

The crosstalk between immunity and cancer in the regulation of tumor growth is considered a hallmark of cancer. Antitumor immunity refers to the innate and adaptive immune responses that regulate cancer development and proliferation. Tumor immune evasion represents a major hindrance to effective anticancer treatment. Extracellular vesicles (EVs) are nano-sized and lipid-bilayer-enclosed particles that are secreted to the extracellular space by all cell types. They are critically involved in numerous biological functions including intercellular communication. Tumor-derived extracellular vesicles (TEVs) can transport a variety of cargo to modulate immune cells in the tumor microenvironment (TME). This review provides the latest update about how tumor cells evade immune surveillance by exploiting TEVs. First, the biogenesis of EVs and the cargo-sorting machinery are discussed. Second, how tumor cells modulate immune cell differentiation, activation, and function via TEVs to evade immune surveillance is illustrated. Last but not least, the novel antitumor strategies that can reverse immune escape are summarized.

Fibrinogen: A new player and target on the formation of pre-metastatic niche in tumor metastasis

Tumor metastasis involves a series of complex and coordinated processes, which is the main cause of patient death and still a significant challenge in cancer treatment. Pre-metastatic niches (PMN), a specialized microenvironment that develops in distant organs prior to the arrival of metastatic cancer cells, plays a crucial role in driving tumor metastasis. The development of PMN depends on a complex series of cellular and molecular components including tumor-derived factors, bone marrow-derived cells, resident immune cells, and extracellular matrix. Fibrinogen, a key factor in the typical blood clotting process, is related to tumor metastasis and prognosis, according to a growing body of evidence in recent years. Fibrinogen has emerged as an important factor in mediating the formation of tumor microenvironment. Nevertheless, a clear and detailed mechanism by which fibrinogen promotes tumor metastasis remains unknown. In this review, we first explore the roles of fibrinogen in the development of PMN from four perspectives: immunosuppression, inflammation, angiogenesis, and extracellular matrix remodeling. We highlight the significance of fibrinogen in shaping PMN and discuss its potential therapeutic values, opening new avenues for targeting fibrinogen to prevent or treat metastasis.

Myeloid-derived suppressor cells in metabolic and cardiovascular disorders

Dysregulation of immune homeostasis can precipitate chronic inflammation, thus significantly contributing to the onset and progression of metabolic and cardiovascular diseases. Myeloid-derived suppressor cells (MDSCs) constitute a heterogeneous population of immature myeloid cells that are mobilized in response to biological stressors such as tissue damage and inflammation. Although MDSCs have been extensively characterized in the contexts of cancer and infectious diseases, emerging evidence highlights their pivotal roles in the pathophysiology of metabolic and cardiovascular disorders. We discuss growing evidence for the involvement of MDSCs in the progression of metabolic and cardiovascular diseases, with the aim of deepening our understanding of MDSCs in cardiometabolic physiology and identifying the necessary steps for the development of innovative MDSC-targeted therapeutic strategies.

Identification of EXO1 as a potential biomarker associated with prognosis and tumor immune microenvironment for specific human cancers

Exonuclease 1 (EXO1) is an evolutionarily conserved exonuclease, which have function on maintaining genomic stability. Elevated expression of EXO1 has been reported in certain cancers. However, a comprehensive pan-cancer analysis of EXO1 is still lacking and its role in human cancer development remains poorly understood. This study aims to investigate the genetic alterations and expression perturbations of EXO1 and evaluate its potential clinical relevance in different cancer types. By employing powerful bioinformatics tools and utilizing data sourced from The Cancer Genome Atlas and the Genotype-Tissue Expression datasets, a comprehensive pan-cancer analysis of EXO1 was conducted, including an examination of gene expression, alterations in genetics, DNA methylation patterns, survival outcomes, clinical traits, immune features, and functional enrichment analysis. EXO1 was found to be highly expressed across 20 tumor types, including lung adenocarcinoma, lung squamous cell carcinoma, and breast invasive carcinoma. The expression levels of EXO1 are frequently associated with later clinical stages and unfavorable outcomes. Genetic alterations in EXO1 were predominantly found to be amplified in a pan-cancer context. A total of 131 missense mutations, 24 truncation mutations, 1 in-frame mutation, 6 splice site mutations, and 1 fusion mutation were identified. Interestingly, a significant co-occurrence of alterations in EXO1 with other ten gene alterations were identified. The expression of EXO1 in multiple tumors showed a significant correlation with tumor mutational burden, microsatellite instability, and genes related to immunological checkpoints. In most types of cancer, a strong correlation exists between the expression of EXO1 and the infiltration of CD4+ Th2 cells, memory CD4+ T cells, myeloid-derived suppressor cells, and common lymphoid progenitors. Analysis of 150 genes related to EXO1 demonstrate an enrichment in processes such as cell cycle regulation, DNA damage repair, and relevant signaling pathways, suggesting a possible mechanism through which EXO1 may facilitate tumor development. This study offers a deep insight into the role of EXO1 in different types of human cancers, indicating that EXO1 could act as an important prognostic biomarker and a therapeutic target for certain types of cancer.

Resistance to immunotherapy in non-small cell lung cancer: Unraveling causes, developing effective strategies, and exploring potential breakthroughs

Over the last two decades, advancements in deciphering the intricate interactions between oncology and immunity have fueled a meteoric rise in immunotherapy for non-small cell lung cancer, typified by an explosive growth of immune checkpoint inhibitors. However, resistance to immunotherapy remains inevitable. Herein we unravel the labyrinthine mechanisms of resistance to immunotherapy, characterized by their involvement of nearly all types of cells within the body, beyond the extrinsic cancer cells, and importantly, such cells are not only (inhibitory or excitatory, or both) signal recipients but also producers, acting in a context-dependent manner. At the molecular level, these mechanisms underlie genetic and epigenetic aberrations, which are regulated by or regulate various protein kinases, growth factors, and cytokines with inherently dynamic and spatially heterogeneous properties. Additionally, macroscopic factors such as nutrition, comorbidities, and the microbiome within and around organs or tumor cells are involved. Therefore, developing therapeutic strategies combined with distinct action informed by preclinical, clinical, and real-world evidence, such as radiotherapy, chemotherapy, targeted therapy, antibody-drug conjugates, oncolytic viruses, and cell-based therapies, may stand as a judicious reality, although the ideality is to overcome resistance point-by-point through a novel drug. Notably, we highlight a realignment of treatment aims, moving the primary focus from eliminating cancer cells -- such as through chemotherapy and radiotherapy -- to promoting immune modulation and underscore the value of regulating various components within the host macro- or micro-environment, as their effects, even if seemingly minimal, can cumulatively contribute to visible clinical benefit when applied in combination with ICIs. Lastly, this review also emphasizes the current hurdles scattered throughout preclinical and clinical studies, and explores evolving directions in the landscape of immunotherapy for NSCLC.

The m6A revolution: transforming tumor immunity and enhancing immunotherapy outcomes

N6-methyladenosine (m6A), the most prevalent RNA modification in eukaryotes, plays a critical role in the development and progression of various diseases, including cancer, through its regulation of RNA degradation, stabilization, splicing, and cap-independent translation. Emerging evidence underscores the significant role of m6A modifications in both pro-tumorigenic and anti-tumorigenic immune responses. In this review, we provide a comprehensive overview of m6A modifications and examine the relationship between m6A regulators and cancer immune responses. Additionally, we summarize recent advances in understanding how m6A modifications influence tumor immune responses by directly modulating immune cells (e.g., dendritic cells, tumor-associated macrophages, and T cells) and indirectly affecting cancer cells via mechanisms such as cytokine and chemokine regulation, modulation of cell surface molecules, and metabolic reprogramming. Furthermore, we explore the potential synergistic effects of targeting m6A regulators in combination with immune checkpoint inhibitor (ICI) therapies. Together, this review consolidates current knowledge on the role of m6A-mediated regulation in tumor immunity, offering insights into how a deeper understanding of these modifications may identify patients who are most likely to benefit from immunotherapies.

Monocytic myeloid-derived suppressor cells contribute to the exacerbation of bone destruction in periodontitis

BACKGROUND

Periodontitis (PD) is a chronic infectious and inflammatory disease characterized by alveolar bone loss. The distinctive activity of immune cells critically exacerbates bone resorption in PD. Myeloid-derived suppressor cells (MDSCs) are known to contribute to various chronic inflammatory conditions, but their role in the pathogenesis and progression of PD remains poorly understood.

METHODS

We used single-cell transcriptomic analysis with human gingival samples and animal models of experimental periodontitis to examine the role of M-MDSCs in PD. We also explored the therapeutic effect of depleting MDSCs on PD in vivo. Additionally, the mechanisms of long non-coding RNA Neat1 and the pathway of NF-κB-dependent "canonical NLRP3 inflammasome activation" in MDSCs were investigated in PD.

RESULTS

In this study, we revealed that monocytic (M)-MDSCs were significantly increased in inflamed gingiva of PD patients compared to healthy individuals. Expansion of M-MDSCs was also observed in the mouse model of ligature-induced periodontitis, and depletion of MDSCs in PD mice could ameliorate alveolar bone loss and reduce periodontal inflammation. Mechanistically, we found that long non-coding RNA Neat1 was significantly upregulated in M-MDSCs, which achieved this proinflammatory effect by activating NF-κB signaling in PD. Furthermore, the pathway of NF-κB-dependent "canonical NLRP3 inflammasome activation" was confirmed in the PD mouse model, accompanied by increased secretion of proinflammatory cytokines that drive alveolar bone loss, including IL-1β, IL-6 and TNF-α.

CONCLUSIONS

In conclusion, this study highlights the pivotal proinflammatory role of M-MDSCs in PD and suggests that targeting these cells may represent a novel immunotherapeutic approach. Future research could focus on strategies to specifically target MDSCs for the treatment of periodontitis.

Unravelling the role of ubiquitin-specific proteases in breast carcinoma: insights into tumour progression and immune microenvironment modulation

Breast cancer is a prevalent malignancy worldwide, and its treatment has increasingly shifted towards precision medicine, with immunotherapy emerging as a key therapeutic strategy. Deubiquitination, an essential epigenetic modification, is regulated by deubiquitinating enzymes (DUBs) and plays a critical role in immune function and tumor progression. Ubiquitin-specific proteases (USPs), a prominent subgroup of DUBs, are involved in regulating immune cell functions, antigen processing, and T cell development in the context of breast cancer. Certain USPs also modulate the differentiation of immune cells, such as myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs), within the breast cancer immune microenvironment. Furthermore, several USPs influence the expression of PD-L1, thus affecting the efficacy of immune checkpoint inhibitors. The overexpression of USPs may promote immune evasion, contributing to the development of treatment resistance. This review elucidates the role of USPs in modulating the immune microenvironment and immune responses in breast cancer. Additionally, it discusses effective strategies for combining USP inhibitors with other therapeutic agents to enhance treatment outcomes. Therefore, targeting USPs presents the potential to enhance the efficacy of immunotherapy and overcome drug resistance, offering a more effective treatment strategy for breast cancer patients.

Cancer vaccines: current status and future directions

Cancer continues to be a major global health burden, with high morbidity and mortality. Building on the success of immune checkpoint inhibitors and adoptive cellular therapy, cancer vaccines have garnered significant interest, but their clinical success remains modest. Benefiting from advancements in technology, many meticulously designed cancer vaccines have shown promise, warranting further investigations to reach their full potential. Cancer vaccines hold unique benefits, particularly for patients resistant to other therapies, and they offer the ability to initiate broad and durable T cell responses. In this review, we highlight the antigen selection for cancer vaccines, introduce the immune responses induced by vaccines, and propose strategies to enhance vaccine immunogenicity. Furthermore, we summarize key features and notable clinical advances of various vaccine platforms. Lastly, we delve into the mechanisms of tumor resistance and explore the potential benefits of combining cancer vaccines with standard treatments and other immunomodulatory approaches to improve vaccine efficacy.

Advances in Antibody-Based Immune-Stimulating Drugs: Driving Innovation in Cancer Therapy

Antibody-based immune-stimulating drugs (ABIs) represent a transformative frontier in cancer immunotherapy, designed to reshape the tumor microenvironment and overcome immune suppression. This study highlighted recent advances in ABIs, including immune-stimulating antibody conjugates (ISACs), bispecific antibodies (BsAbs), and checkpoint blockade enhancers, with a focus on their mechanisms of action, clinical advancements, and challenges. Preclinical findings revealed that ISACs effectively boost overall anti-cancer immunity by reprogramming tumor-associated macrophages, enhancing T cell activation, and engaging other immune pathways. Similarly, BsAbs effectively redirect immune cells to tumors, achieving significant tumor regression. Additionally, artificial intelligence (AI) is revolutionizing the development of ABIs by optimizing drug design, identifying novel targets, and accelerating preclinical validation, enabling personalized therapeutic strategies. Despite these advancements, significant challenges remain, including immune resistance and off-target effects. Future research should prioritize next-generation multifunctional antibodies, AI-driven innovations, and combination therapies to enhance efficacy and expand therapeutic applications. Connecting these gaps could unlock the full potential of ABIs, upgrading cancer treatment and improving outcomes for patients with refractory or resistant tumors.

Reinforcing cancer immunotherapy with engineered porous hollow mycobacterium tuberculosis loaded with tumor neoantigens

BACKGROUND

Enhancing antigen cross-presentation is essential for the development of a tumor neoantigen vaccine. One approach is to stimulate antigen-presenting cells (APCs) to uptake neoantigens. Mycobacterium tuberculosis (MTb) contains pathogen-associated molecular patterns (PAMPs) recognized by APCs and adhesion molecules that facilitate MTb invasion of APCs. Therefore, we suggest using MTb as a carrier to enhance APC phagocytosis of neoantigens, thereby promoting antigen cross-presentation.

METHODS

The successful preparation of the MTb carrier (phMTb) was confirmed through electron and confocal microscopy. Fluorescence microscopy was used to detect PAMPs and adhesion molecules on phMTb as well as to observe its role in aiding dendritic cells (DCs) in antigen uptake into endosomes or lysosomes. Flow cytometry was used to assess the retention of PAMPs and adhesion molecules on phMTb, investigate antigen uptake by DCs, evaluate their activation and maturation status, examine the presentation of tumor neoantigens, and analyze immune cells in draining lymph nodes and tumor tissues. The efficacy of phMTb vaccine formulations in combination with anti-programmed cell death protein 1 (PD-1) antibody therapy was assessed using the MC38 mouse tumor models. Adverse effects were evaluated through H&E staining of major organs, assessment of reproductive capability and detection of biochemical indices.

RESULTS

The engineered porous hollow phMTb carrier successfully encapsulated model tumor neoantigens, with or without the adjuvant CpG. The phMTb retained PAMPs and adhesion molecules on its surface, similar to the parental MTb, thereby enhancing DC uptake of phMTb and its formulations containing tumor neoantigens and CpG. Vaccines formulated with phMTb facilitated DC maturation, activation, cross-presentation of tumor neoantigens, and promoted migration of phMTb-laden DCs to lymph nodes, enhancing effector and memory CD8+ T lymphocyte function. In murine tumor models, immunization with phMTb-formulated neoantigen vaccines elicited a robust tumor-specific cytotoxic T lymphocyte immune response with minimal adverse effects. Additionally, vaccination with phMTb-formulated neoantigen vaccines effectively reversed the tumor's immune-suppressive microenvironment. Concurrent administration of the PD-1 antibody with the phMTb-formulated neoantigen vaccine exhibited significant synergistic therapeutic effects.

CONCLUSIONS

The results of our study highlight the potential clinical translation of personalized tumor neoantigen vaccines using the phMTb carrier.

Phase I/II Study of the Aurora Kinase A Inhibitor Alisertib and Pembrolizumab in Refractory, Rb-Deficient Head and Neck Squamous Cell Carcinomas

PURPOSE

Effective therapy for recurrent head and neck squamous cell carcinoma (HNSCC) that is refractory to chemotherapy and immunotherapy is a considerable need. Aurora kinase A inhibition leads to apoptosis and immunogenic cell death in preclinical models of human papilloma virus (HPV)-driven cancers.

PATIENTS AND METHODS

Alisertib was administered orally twice daily on days 1-7 and pembrolizumab on day 1 of a 21-day cycle to adults with advanced solid tumors (phase I) or with immunotherapy- and platinum-resistant, HPV-positive HNSCC (phase II).

RESULTS

The recommended phase II alisertib dose was 40 mg, which had only the expected toxicity including cytopenia that led to dose reductions in two phase II patients at cycles 13 and 16. We saw no objective responses, but the combination led to prolonged stable disease (SD) in several patients, including two of 10 phase I patients (8 and 27 months). Eight of the 15 HPV-positive patients had SD, of which four (heavily pretreated) had ≥6 months, with median overall and progression-free survival durations of 16.8 and 1.4 months, respectively. In circulating immune cells and plasma, patients with SD had markedly higher levels of HLA de novo resistance-expressing NK cells than did progressive disease patients who demonstrated a more immunosuppressive and inflammatory profile. Pharmacokinetics did not indicate any significant drug-drug interactions between pembrolizumab and alisertib.

CONCLUSIONS

The combination of alisertib and pembrolizumab was well tolerated and led to prolonged SD in some immunotherapy-resistant patients, supporting our hypothesis that Aurora kinase A inhibition can reverse immunotherapy resistance of retinoblastoma protein-deficient HNSCC.

IGF2-IGF1R signaling inhibition delays the growth of IGF2-high colorectal cancer by modulating MDSCs

Approximately 22 % of human colorectal cancers (CRC) are characterized by IGF2 overexpression, and the tumor-promoting role of IGF2 has been widely reported. Despite promising preclinical results, IGF2 signaling inhibition therapy has exhibited limited efficacy in treating unselected patients with CRC. Recent evidence suggests that IGF2-high CRC are more sensitive to IGF2 signaling blockade therapy in immune-deficient mice, suggesting that IGF2-high CRC can benefit from IGF2 signaling blockade therapy. However, T cells are absent in immunodeficient mice, and the effect of blocking IGF2 signaling on T cell-mediated antitumor immunity remains unknown. Herein, using an implanted mouse tumor model in immunocompetent hosts, we report that PQ401, an IGF2-IGF1R inhibitor, significantly inhibited the growth of IGF2-high CRC cells. PQ401 treatment increased the infiltration and function of tumor-infiltrating CD4+ and CD8+ T cells in a T cell-extrinsic manner. Our findings suggest that myeloid-derived suppressor cells (MDSCs) highly express the IGF2 receptor IGF1R. Moreover, PQ401 treatment inhibits the suppressive function and recruitment of MDSCs, thereby promoting the anti-tumor activity of T cells. These results provide a potential therapeutic regimen for patients with IGF2-high CRC.

HDAC1-3 inhibition triggers NEDD4-mediated CCR2 downregulation and attenuates immunosuppression in myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSCs) play a critical role in cancer progression and resistance, thus representing promising targets for immunotherapy. Despite the established role of histone deacetylases (HDACs) in epigenetic regulation of cell fate and function, their specific impact on MDSCs remains elusive. We sought to investigate the effects and underlying mechanisms of HDAC on MDSCs using various HDAC inhibitors. Our results indicate that HDAC1-3 inhibitors reduce CCR2 expression, a chemokine receptor that mediates the migration of monocytic (M-)MDSCs to tumors and attenuated the immunosuppressive activity of MDSCs. In an orthotropic hepatocellular carcinoma (HCC) murine model, HDAC1-3 inhibitors reduced the infiltration of M-MDSCs, increased the number of natural killer cells in tumors, and suppressed tumor growth. Our results also suggest that HDAC1-3 inhibitors potentiate the antitumor effects of anti-programmed cell death protein 1 antibodies. ATAC-seq and RNA-seq analyses revealed 115 genes epigenetically upregulated by HDAC1-3 inhibitors, primarily linked to transcriptional regulation and ubiquitination. We further elucidated that HDAC1-3 inhibitors facilitate CCR2 protein degradation through ubiquitination-mediated by NEDD4 E3 ligase. Our findings reveal a novel mechanism of action of HDAC1-3 inhibitors in MDSCs and suggest a potential synergistic immunotherapy strategy for clinical benefit in HCC.

Current status and future prospects of molecular imaging in targeting the tumor immune microenvironment

Molecular imaging technologies have significantly transformed cancer research and clinical practice, offering valuable tools for visualizing and understanding the complex tumor immune microenvironment. These technologies allow for the non-invasive examination of key components within the tumor immune microenvironment, including immune cells, cytokines, and stromal cells, providing crucial insights into tumor biology and treatment responses. This paper reviews the latest advancements in molecular imaging, with a focus on its applications in assessing interactions within the tumor immune microenvironment. Additionally, the challenges faced by molecular imaging technologies are discussed, such as the need for highly sensitive and specific imaging agents, issues with data integration, and difficulties in clinical translation. The future outlook emphasizes the potential of molecular imaging to enhance personalized cancer treatment through the integration of artificial intelligence and the development of novel imaging probes. Addressing these challenges is essential to fully realizing the potential of molecular imaging in improving cancer diagnosis, treatment, and patient outcomes.

Reprogramming the melanoma and immunosuppressive myeloid cells with esomeprazole-loaded PLGA nanoparticles

Proton pump inhibitors have been explored for potentiating cancer therapies via reverting the tumor acidity and promoting the activation of anti-tumor immune responses. To regulate the intracellular pH of melanoma and immunosuppressive myeloid cells, we developed poly(L-lactide-co-glycolide) nanoparticles loaded with esomeprazole (ESO-NPs). The effect of ESO-NPs on melanoma cells was observed as alkalinization and reduction of melanin content accompanied by a decrease of microphthalmia-associated transcription factor (MITF), poliovirus receptor (PVR), and programmed death ligand 1 (PD-L1) immune checkpoint expression. ESO-NP treatment of melanoma-patient-derived and in vitro-induced myeloid-derived suppressor cells (MDSCs) reduced the expression of immunosuppression-associated molecules PD-L1, CD206, and CD163 on patient-derived myeloid cells while inducing the expression of co-stimulatory molecule CD86 and HLA-DR in the in vitro model. Our findings suggest that reprogramming the intracellular pH of melanoma and immune-suppression-associated myeloid cells with ESO-NPs can modulate the expression of proteins involved in resistance to cancer therapy and immunosuppression, thus potentially improving the response to immunotherapies.

Targeting lipid metabolism: novel insights and therapeutic advances in pancreatic cancer treatment

Lipid metabolism in cancer is characterized by dysregulated lipid regulation and utilization, critical for promoting tumor growth, survival, and resistance to therapy. Pancreatic cancer (PC) is a highly aggressive malignancy of the gastrointestinal tract that has a dismal 5-year survival rate of less than 10%. Given the essential function of the pancreas in digestion, cancer progression severely disrupts its function. Standard treatments for PC such as surgical resection, chemotherapy, and radiotherapy. However, these therapies often face significant challenges, including biochemical recurrence and drug resistance.Given these limitations, new therapeutic approaches are being developed to target tumor metabolism. Dysregulation of cholesterol biosynthesis and alterations in fatty acids (FAs), such as palmitate, stearate, omega-3, and omega-6, have been observed in pancreatic cancer. These lipids serve as energy sources, signaling molecules, and essential components of cell membranes. Their accumulation fosters an immunosuppressive tumor microenvironment that supports cancer cell proliferation and metastasis.Moreover, lipid metabolism dysregulation within immune cells, particularly T cells, impairs immune surveillance and weakens the body's defenses against cancer. Abnormal lipid metabolism also contributes to drug resistance in PC. Despite these challenges, targeting lipid metabolism may offer a promising therapeutic strategy. By enhancing lipid peroxidation, the induction of ferroptosis-a form of regulated cell death-could impair the survival of PC cells and hinder disease progression.

Hyperactivity of the IL-33-ILC2s-IL-13-M-MDSCs axis promotes cervical cancer progression

The interleukin-33(IL-33) - group 2 innate lymphoid cells (ILC2s) - interleukin-13(IL-13) - monocytic myeloid-derived suppressor cells (M-MDSCs) axis plays a critical role in promoting immune evasion in tumors; however, its specific function in cervical cancer remains poorly understood. In this study, we observed that the proportion of IL-33-ILC2s-IL-13-M-MDSCs were significantly elevated in both cervical cancer patients and the subcutaneous U14 cervical cancer mouse model, compared to normal controls. Our results suggest that IL-33 stimulates ILC2s to secrete IL-13, which, in turn, regulates M-MDSCs to enhance their immune evasion capabilities. Notably, in vitro blockade of IL-33 and IL-13 partially restored the levels and functions of both ILC2s and M-MDSCs. In conclusion, these findings imply that the overactivation of the IL-33-ILC2s-IL-13-M-MDSCs axis may contribute to cervical cancer progression. However, further in vivo blockade studies are required to fully elucidate the precise mechanisms underlying this interaction and to assess its potential therapeutic implications for cervical cancer.

Unveiling immune resistance mechanisms in nasopharyngeal carcinoma and emerging targets for antitumor immune response: tertiary lymphoid structures

Nasopharyngeal carcinoma (NPC) is a prevalent malignancy in China, commonly associated with undifferentiated cell types and Epstein-Barr virus (EBV) infection. The presence of intense lymphocytic infiltration and elevated expression of programmed cell death ligand 1(PD-L1) in NPC highlights its potential for immunotherapy, yet current treatment outcomes remain suboptimal. In this review, we explore the tumor microenvironment of NPC to better understand the mechanisms of resistance to immunotherapy, evaluate current therapeutic strategies, and pinpoint emerging targets, such as tertiary lymphoid structures (TLSs), that could enhance treatment outcomes and prognostic accuracy. TLSs have demonstrated positive prognostic value in NPC, making them a promising target for future therapies. This review summarizes the key characteristics of TLSs and latest research in the context of NPC. We are optimistic that targeting TLSs could improve immunotherapy outcomes for NPC patients, ultimately leading to more effective treatment strategies and better patient survival.

Epigenetic Regulation of Stromal and Immune Cells and Therapeutic Targets in the Tumor Microenvironment

The tumor microenvironment (TME) plays a pivotal role in neoplastic initiation and progression. Epigenetic machinery, governing the expression of core oncogenes and tumor suppressor genes in transformed cells, significantly contributes to tumor development at both primary and distant sites. Recent studies have illuminated how epigenetic mechanisms integrate external cues and downstream signals, altering the phenotype of stromal cells and immune cells. This remolds the area surrounding tumor cells, ultimately fostering an immunosuppressive microenvironment. Therefore, correcting the TME by targeting the epigenetic modifications holds substantial promise for cancer treatment. This review synthesizes recent research that elucidates the impact of specific epigenetic regulations-ranging from DNA methylation to histone modifications and chromatin remodeling-on stromal and immune cells within the TME. Notably, we highlight their functional roles in either promoting or restricting tumor progression. We also discuss the potential applications of epigenetic agents for cancer treatment, envisaging their ability to normalize the ecosystem. This review aims to assist researchers in understanding the dynamic interplay between epigenetics and the TME, paving the way for better epigenetic therapy.