Regulation and Function of the PD-L1 Checkpoint

Cancer-Associated Fibroblasts as the "Architect" of the Lung Cancer Immune Microenvironment: Multidimensional Roles and Synergistic Regulation with Radiotherapy

Cancer-associated fibroblasts (CAFs), as the "architect" of the immune microenvironment in lung cancer, play a multidimensional role in tumor progression and immune regulation. In this review, we summarize the heterogeneity of the origin and the molecular phenotype of CAFs in lung cancer, and explore the complex interactions between CAFs and multiple components of the tumor microenvironment, including the regulatory relationships with innate immune cells (e.g., tumor-associated macrophages, tumor-associated neutrophils), adaptive immune cells (e.g., T cells), and extracellular matrix (ECM). CAFs significantly influence tumor progression and immunomodulation through the secretion of cytokines, remodeling of the ECM, and the regulation of immune cell function significantly affects the immune escape and treatment resistance of tumors. In addition, this review also deeply explored the synergistic regulatory relationship between CAF and radiotherapy, revealing the key role of CAF in radiotherapy-induced remodeling of the immune microenvironment, which provides a new perspective for optimizing the comprehensive treatment strategy of lung cancer. By comprehensively analyzing the multidimensional roles of CAF and its interaction with radiotherapy, this review aims to provide a theoretical basis for the precise regulation of the immune microenvironment and clinical treatment of lung cancer.

Simvastatin inhibits PD-L1 via ILF3 to induce ferroptosis in gastric cancer cells

The treatment of gastric cancer remains challenging, with immunotherapy serving as a critical component of the holistic approach to its treatment. The results of this study indicated that statins could decrease the serum levels of interleukin-enhancing binding factor 3 (ILF3) and programmed cell death ligand 1(PD-L1) in GC patients and improve their prognosis. Functional experiments demonstrated that simvastatin induced ferroptosis by inhibiting ILF3 in GC cells and enhanced the killing effect of activated CD8+ T cells on GC cells. The CUT&Tag assay revealed that, mechanistically, simvastatin inhibited ILF3 expression by reducing the acetylation level at residue site H3K14 in ILF3. Next-generation sequencing and Kyoto Encyclopedia of Genes and Genomes analysis revealed that ILF3 regulated PD-L1 expression through the DEPTOR/mTOR signaling pathway. Overall, simvastatin induced ferroptosis in GC cells by inhibiting ILF3 expression while promoting the activation of CD8+ T cells to augment antitumor immune responses, thereby facilitating synergistic immunotherapy.

Orlistat facilitates immunotherapy via AKT-FOXO3a-FOXM1-mediated PD-L1 suppression

BACKGROUND

The immunotherapy targeting cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) and programmed cell death ligand-1 (PD-L1) has achieved significant breakthroughs, but further improvements are still needed in cancer treatment.

METHODS

We investigated orlistat, a drug approved by the Food and Drug Administration for the treatment of obesity and found that it can enhance the efficacy of CTLA-4 blockade immunotherapy. We conducted both in vivo and in vitro experiments to explore the mechanism by which orlistat increased antitumor immunity.

RESULTS

Orlistat enhances the efficacy of anti-CTLA-4 immunotherapy by suppressing tumor cell PD-L1 protein expression and boosting the transcription of interferon-stimulated genes (ISGs) and MHC-I. Mechanistically, orlistat inhibits AKT activity and subsequent phosphorylation of forkhead box O3a (FOXO3a) at its threonine (T) 32, serine (S) 253, thereby downregulating Forkhead box M1 (FOXM1) expression, which ultimately suppresses PD-L1 transcription. Specifically, inhibition of FOXM1 leads to FOXO3a accumulation through impaired AKT activity. FOXM1 activates protein kinase B (AKT) via acting as a scaffold to facilitate 3-phosphoinositide-dependent protein kinase 1 (PDK1) and AKT and interaction. In addition, orlistat enhances phosphorylated signal transducer and activator of transcription 1 (p-STAT1) at tyrosine (Y) 701, resulting in upregulation of ISGs and MHC-I.

CONCLUSIONS

Orlistat plays a crucial role in modulating the immune response and supporting the combination with CTLA-4 blockade to promote antitumor immunotherapy.

Recent Research on Role of p53 Family in Small-Cell Lung Cancer

Small-cell lung cancer (SCLC) is a highly aggressive malignancy characterized by rapid proliferation, early metastasis, and frequent recurrence, which contribute to a poor prognosis. SCLC is defined by the near-universal inactivation of key tumor suppressor genes, notably TP53 and RB1, which play central roles in its pathogenesis and resistance to therapy. The p53 family of proteins, including p53, p63, and p73, is essential to maintaining cellular homeostasis and tumor suppression. TP53 mutations are almost ubiquitous in SCLC, leading to dysregulated apoptosis and cell cycle control. Moreover, p73 shows potential as a compensatory mechanism for p53 loss, while p63 has a minimal role in this cancer type. In this review, we explore the molecular and functional interplay of the p53 family in SCLC, emphasizing its members' distinct yet interconnected roles in tumor suppression, immune modulation, and therapy resistance. We highlight emerging therapeutic strategies targeting these pathways, including reactivating mutant p53, exploiting synthetic lethality, and addressing immune evasion mechanisms. Furthermore, this review underscores the urgent need for novel, isoform-specific interventions to enhance treatment efficacy and improve patient outcomes in this challenging disease.

Apelin/APJ: Another Player in the Cancer Biology Network

The apelinergic system exerts multiple biological activities in human pathologies, including cancer. Overactivation of apelin/APJ, which has been detected in many malignant tumors, and the strong correlation with progression-free and overall survival, suggested the role of an oncogene for the apelin gene. Emerging evidence sheds new light on the effects of apelin on cellular functions and homeostasis in cancer cells and supports a direct role for this pathway on different hallmarks of cancer: "sustaining proliferative signaling", "resisting cell death", "activating invasion and metastasis", "inducing/accessing vasculature", "reprogramming cellular metabolism", "avoiding immune destruction" and "tumor-promoting inflammation", and "enabling replicative immortality". This article reviews the currently available literature on the intracellular processes regulated by apelin/APJ, focusing on those pathways correlated with tumor development and progression. Furthermore, the association between the activity of the apelinergic axis and the resistance of cancer cells to oncologic treatments (chemotherapy, immunotherapy, radiation) suggests apelin/APJ as a possible target to potentiate traditional therapies, as well as to develop diagnostic and prognostic applications. This issue will be also covered in the review.

CXCR2P1 enhances the response of gastric cancer to PD-1 inhibitors through increasing the immune infiltration of tumors

Background

Recent years, immunotherapy has emerged as a pivotal approach in cancer treatment. However, the response of gastric cancer to immunotherapy exhibits significant heterogeneity. Therefore, the early identification of gastric cancer patients who are likely to benefit from immunotherapy and the discovery of novel therapeutic targets are of critical importance.

Materials and methods

We collected data from European Nucleotide Archive (ENA) and Gene Expression Omnibus (GEO) databases. In project PRJEB25780, we performed WGCNA analysis and Lasso regression and chose CXCR2P1 for the subsequent analysis. Then, we compared the expression difference of CXCR2P1 among different groups. Kaplan-Meier curve was used to analyze the prognostic value of CXCR2P1, which was validated by project IMvigor210 and GEO datasets. ESTIMATE and CIBERSORT algorithm were used to evaluate the reshaping effect of CXCR2P1 to immune microenvironment of tumor. Differentially expressed genes (DEG) analysis, enrichGO analysis, Gene Set Enrichment Analysis (GSEA) and co-expression analysis were used to explore the cell biological function and signaling pathway involved in CXCR2P1.

Results

WGCNA identified CXCR2P1 as a hub gene significantly associated with immune response to PD-1 inhibitors in gastric cancer. CXCR2P1 expression was elevated in responders and correlated with better prognosis. Functional analysis revealed its role in reshaping the tumor immune microenvironment by promoting immune cell infiltration, including M1 macrophages, activated CD4+ T cells, and follicular helper T cells. CXCR2P1 enhanced antigen presentation via the MHC-II complex, influenced key immune pathways, such as Toll-like receptor signaling and T-cell activation, which led to the up-regulation of expression of PD-L1. GSEA showed CXCR2P1 were correlated with microRNAs. Through DEG analysis and expression analysis, MIR215 was identified as a potential direct target of CXCR2P1.

Conclusion

High expression of CXCR2P1 is correlated with better response to PD-1 inhibitor. It reshapes the immune microenvironment by increasing immune infiltration and changing the fraction of immune cells. In tumor immune microenvironment, CXCR2P1 can promote inflammation, enhance antigen presentation and activate the PD-1/PD-L1-related signaling pathway, which might be achieved by CXCR2P1-MIR215 axis.

Massively parallel interrogation of human functional variants modulating cancer immunosurveillance

Anti-PD-1/PD-L1 immune checkpoint blockade (ICB) therapy has revolutionized clinical cancer treatment, while abnormal PD-L1 or HLA-I expression in patients can significantly impact the therapeutic efficacy. Somatic mutations in cancer cells that modulate these critical regulators are closely associated with tumor progression and ICB response. However, a systematic interpretation of cancer immune-related mutations is still lacking. Here, we harnessed the ABEmax system to establish a large-scale sgRNA library encompassing approximately 820,000 sgRNAs that target all feasible serine/threonine/tyrosine residues across the human genome, which systematically unveiled thousands of novel mutations that decrease or augment PD-L1 or HLA-I expression. Beyond residues associated with phosphorylation events, our screens also identified functional mutations that affect mRNA or protein stability, DNA binding capacity, protein-protein interactions, and enzymatic catalytic activity, leading to either gene inactivation or activation. Notably, we uncovered certain mutations that concurrently modulate PD-L1 and HLA-I expression, represented by the clinically relevant mutation SETD2_Y1666. We demonstrated that this mutation induces consistent phenotypic effects across multiple cancer cell lines and enhances the efficacy of immunotherapy in different tumor models. Our findings provide an unprecedented resource of functional residues that regulate cancer immunosurveillance, offering valuable guidance for clinical diagnosis, ICB therapy, and the development of innovative drugs for cancer treatment.

Bioinformatics and experimental approach reveal potential prognostic and immunological roles of key mitochondrial metabolism-related genes in cervical cancer

Background

Metabolic remodeling is the hallmark of cancer. In recent years, mitochondrial metabolism (MM) has been considered essential in tumorigenesis and cancer progression. Understanding the role of MM in cervical cancer (CC) can provide insights into disease progression and potential therapeutic targets.

Methods

Clinical data of CC patients was downloaded from the UCSC Xena dataset, and differentially expressed genes (DEGs) were identified between tumor and normal samples. MM-related genes (MMRGs) were screened from the MSigDB database. DEGs and MMRGs were then intersected to identify differentially expressed MMRGs. A prognostic risk model was constructed based on these intersecting genes through Cox regression analysis, and its association with the tumor microenvironment and immune checkpoint-related genes was evaluated. Hub genes' expression was evaluated in cells through qRT-PCR. Additionally, drug sensitivity analysis was conducted to explore potential therapeutic drugs.

Results

We identified 259 overlapping genes between DEGs and MMRGs, with 55 being prognosis-related. Two molecular clusters were revealed, with C1 exhibiting poorer prognosis. A prognostic risk model comprising five genes (BDH1, MIR210, MSMO1, POLA1, and STARD3NL) was established, showing significant associations with survival outcomes of CC patients. Functional enrichment analysis revealed that DEGs between high- and low-risk groups were tightly associated with the immune system. Analysis of the immune microenvironment showed significant differences between different risk groups, with higher immune and ESTIMATE scores observed in the low-risk group. Additionally, expression levels of immune checkpoint-related genes were significantly correlated with the risk score. Drug sensitivity analysis identified potential therapeutic agents correlated with the expression of the five prognostic genes.

Conclusion

Our findings underscore the importance of MM in CC progression and provide potential therapeutic targets for CC.

The application of emerging immunotherapy in the treatment of prostate cancer: progress, dilemma and promise

In recent years, there has been a growing trend towards the utilization of immunotherapy techniques for the treatment of cancer. Some malignancies have acquired significant progress with the use of cancer vaccines, immune checkpoint inhibitors, and adoptive cells therapy. Scholars are exploring the aforementioned methods as potential treatments for advanced prostate cancer (PCa) due to the absence of effective adjuvant therapy to improve the prognosis of metastatic castration-resistant prostate cancer (mCRPC). Immunotherapy strategies have yet to achieve significant advancements in the treatment of PCa, largely attributed to the inhibitory tumor microenvironment and low mutation load characteristic of this malignancy. Hence, researchers endeavor to address these challenges by optimizing the design and efficacy of immunotherapy approaches, as well as integrating them with other therapeutic modalities. To date, studies have also shown potential clinical benefits. This comprehensive review analyzed the utilization of immunotherapy techniques in the treatment of PCa, assessing their advantages and obstacles, with the aim of providing healthcare professionals and scholars with a comprehensive understanding of the progress in this field.

Targeting tumor monocyte-intrinsic PD-L1 by rewiring STING signaling and enhancing STING agonist therapy

STING is an important DNA sensing machinery in initiating immune response, yet therapies targeting STING have shown poor outcomes in clinical trials. Here, we reveal that STING signaling induces PD-L1hi tumor monocytes (Tu.Mons) that dominate the resistance against STING agonist therapy. Cell-intrinsic PD-L1, induced by the STING-IRF3-IFN-I axis, is identified as the driving factor for protumoral PD-L1hi Tu.Mons. Notably, TLR2-activated Tu.Mons resist STING-induced upregulation of cell-intrinsic PD-L1 and the associated protumoral functions. Mechanistically, TLR2 stimulation remodels STING signaling by facilitating STING and TRAF6 interaction, which suppresses the IRF3-IFN-I response and enhances NF-κB activation. Moreover, we demonstrate that combining STING agonists with TLR2 agonist pretreatment significantly improves antitumor efficacy in murine syngeneic and humanized models. Our findings uncover a protumoral aspect of STING activation mediated by cell-intrinsic PD-L1 and propose a promising strategy to boost antitumor immunity by fine-tuning STING signaling outputs.

Co-delivery of axitinib and PD-L1 siRNA for the synergism of vascular normalization and immune checkpoint inhibition to boost anticancer immunity

Immune checkpoint inhibition (ICI) has become the mainstay of immunotherapy for the treatment of renal cell carcinoma (RCC). However, only a small portion of patients exhibit a positive response to PD-1/PD-L1 blockade therapy and the key reason is that RCC belongs to a vascular-rich tumor for promoting immunosuppression. Specifically, the dysfunctional tumor vasculature hinders effector T cell infiltration and induces immunosuppressive tumor microenvironment via the release of cytokine, which attenuates the therapeutic efficacy of ICI. Therefore, regulating abnormal tumor vasculature may be a promising strategy to overcome the immunosuppressive microenvironment and enhance ICI therapy. Here, we propose an NGR peptide-modified actively targeted liposome (Axi/siRNAPD-L1@NGR-Lipo) to encapsulate the anti-angiogenic agents Axitinib and PD-L1 siRNA to promote tumor vasculature normalization and relieve immune evasion for enhanced anti-tumor immunotherapy. With NGR-mediated tumor homing and active targeting, Axi/siRNAPD-L1@NGR-Lipo could act on tumor vascular endothelial cells to inhibit neo-angiogenesis, increase pericyte coverage and vascular perfusion, and normalize the structure and function of tumor blood vessels. Meanwhile, it also enhanced immune effector T cells and NK cells infiltration and reduced the proportion of immunosuppressive T cells including MDSC cells and Tregs, thus improving the tumor immunosuppressive microenvironment. Moreover, Axi/siRNAPD-L1@NGR-Lipo reduced the expression of PD-L1 protein in tumor cells, restored the recognition and killing ability of cytotoxic T cells, and relieved immune evasion. As expected, Axi/siRNAPD-L1@NGR-Lipo displayed superior anti-tumor and anti-metastatic efficacy in mice bearing RCC. Overall, this study demonstrated the important potential of regulating abnormal tumor vasculature to reshape the immunosuppressive microenvironment and boost ICI therapy, which represents a promising avenue for the synergistic anti-tumor with cancer immunotherapy.

PRMT3 drives PD-L1-mediated immune escape through activating PDHK1-regulated glycolysis in hepatocellular carcinoma

Aberrant expression of programmed death ligand-1 (PD-L1) facilitates tumor immune evasion. Protein arginine methyltransferase 3 (PRMT3), a member of type I PRMT family, mediates asymmetric dimethylarginine (ADMA) modification of various substrate proteins. This study investigates the role of PRMT3 in PD-L1-associated tumor immunosuppression in hepatocellular carcinoma (HCC). Hepatocyte-specific knockout of Prmt3 significantly suppressed HCC progression in DEN-CCL4-treated mice. Knockout of Prmt3 in HCC cells markedly increased CD8+ T cell infiltration, and reduced lactate production in tumors. PRMT3 interacted with pyruvate dehydrogenase kinase 1 (PDHK1), asymmetric dimethylation of PDHK1 at arginine 363 and 368 residues and increased its kinase activity. The R363/368 K mutant or inhibition of PDHK1 by JX06 blocked the effect of PRMT3 on lactate production. JX06 treatment also attenuated the tumor-promoting role of PRMT3 in HCC in vitro and in vivo. Furthermore, RNA-seq analysis revealed that knockout of PRMT3 downregulates the tumor-associated immune checkpoint, PD-L1, in tumor tissues. Chromatin immunoprecipitation (ChIP) assay demonstrated that PRMT3 promotes lactate-induced PD-L1 expression by enhancing the direct binding of histone H3 lysine 18 lactylation (H3K18la) to the PD-L1 promoter. Tissue microarray analysis showed a positive correlation between PRMT3 and PD-L1 expression in HCC patients. Anti-PD-L1 treatment reversed PRMT3-induced tumor growth and restored CD8+ T cell infiltration. Our research links PRMT3-mediated metabolic reprogramming and immune evasion, revealing that the PRMT3-PDHK1-lactate-PD-L1 axis may be a potential target for improving the efficacy of immunotherapy in HCC.

A disproportionality analysis of real-world events from the FDA Adverse Event Reporting System (FAERS) for Atezolizumab

BACKGROUND

An increasing number of clinical studies have highlighted the use of atezolizumab in tumor immunotherapy. However, There is still a lack of comprehensive research on its associated adverse events (AEs). To improve our understanding of its toxicological profile and to provide valuable clinical insights regarding into the effectiveness of immunotherapy, this study utilized data from the US Food and Drug Administration Adverse Event Reporting System (FAERS) to conduct a retrospective analysis of AEs linked to atezolizumab.

METHODS

We extracted the reports of AEs related to atezolizumab from the FAERS database from the first quarter of 2004 to the first quarter of 2024. We quantified them using the reporting odds ratio (ROR) and proportional reporting ratio (PRR), along with chi-square value (χ²), and conducted systematic classification of the AE signal mining results through SAS 9.4 software.

RESULTS

A total of 19,563 valid reports were incorporated, involving 20 distinct system organ class categories. The AEs related to atezolizumab, reported at the preferred term level, mainly encompassed anemia [ROR 2.33, 95% confidence interval (CI) lower limit 2.09, PRR 2.31, χ² 255.977], febrile neutropenia (ROR 2.81, 95% CI lower limit 2.50, PRR 2.79, χ² 333.586), neutrophil count decreased (ROR 2.14, 95% CI lower limit 1.89, PRR 2.13, χ² 150.688), white blood cell count decreased (ROR 2.35, 95% CI lower limit 2.03, PRR 2.34, χ² 136.673), sepsis (ROR 2.21, 95% CI lower limit 1.91, PRR 2.20, χ² 117.741), alanine aminotransferase increased (ALT) (ROR 2.86, 95% CI lower limit 2.44, PRR 2.85, χ² 180.031), and aspartate aminotransferase increased (AST) (ROR 2.79, 95% CI lower limit 2.38, PRR 2.78, χ² 170.955).

CONCLUSIONS

Apart from various degrees of hepatotoxicity, such as increased ALT and AST, the immune-related hematological toxicity of atezolizumab should also be noted. In clinical practice, healthcare providers should always be vigilant for the occurrence of such medication-related AEs and take measures to enhance the safety of clinical medication use.

NSUN2/ALYREF axis-driven m5C methylation enhances PD-L1 expression and facilitates immune evasion in non-small-cell lung cancer

Non-small-cell lung cancer (NSCLC) represents a highly prevalent form of malignancy. 5-methylcytosine (m5C) methylation functions as a key post-transcriptional regulatory mechanism linked to cancer progression. The persistent expression of PD-L1 in tumor cells plays a pivotal role in facilitating immune evasion and promoting T-cell exhaustion. However, the involvement of m5C in NSCLC immune evasion remains inadequately understood. This study seeks to explore the function of the m5C methyltransferase NSUN2 in modulating PD-L1 expression and facilitating immune evasion in NSCLC. Our findings indicate elevated levels of NSUN2 and ALYREF in NSCLC, and both promote the growth of NSCLC cells and the progression of lung cancer. Moreover, the expression of PD-L1 in NSCLC tissues positively correlates with NSUN2 and ALYREF expression. We then discovered that PD-L1 acts as a downstream target of NSUN2-mediated m5C modification in NSCLC cells. Knocking down NSUN2 significantly reduces m5C modification of PD-L1 mRNA, thereby decreasing its stability via the m5C reader ALYREF-dependent manner. Furthermore, inhibiting NSUN2 enhanced CD8+ T-cell activation and infiltration mediated by PD-L1, thereby boosting antitumor immunity, as confirmed in both in vitro and in vivo experiments. Collectively, these results suggested that NSUN2/ALYREF/PD-L1 axis plays a critical role in promoting NSCLC progression and tumor cell immune suppression, highlighting its potential as a novel therapeutic strategy for NSCLC immunotherapy.

Deciphering the Role of CD14 in Helicobacter Pylori-associated Gastritis and Gastric Cancer: Combing Bioinformatics Analysis and Experiments

Background: Gastric cancer (GC) is the third leading cause of cancer-related death and is associated with high mortality and morbidity. Helicobacter pylori (HP) infection is the most important cause of GC. We aimed to identify the core genes of HP caused GC and further elucidate the underlying mechanisms. Methods: GC and HP associated gastritis (HPAG) gene expression data were sourced from Gene Expression Omnibus. Key genes affecting GC prognosis were identified using Cytoscape software. Patient groups were formed based on key gene expression, and the immune analyses were performed with R. MNU, derived from nitrite by HP, was given to GC mice (240ppm) for histology and fluorescence assays. For in vitro experiments, cells received MNU (20 μM) stimulation for 24 hours. Results: CD14 was the only key gene identified. A total of 412 GC patients were divided into CD14-high and CD14-low groups. The two groups showed significant differences in immune cell populations and immune checkpoints. In particular, there was a notable increase in M2 macrophages in GC patients with high CD14 expression (P <0.001). GC Patients with high CD14 expression exhibited a more pronounced immune response than those with low CD14 expression, and elevated CD14 expression positively correlated with the efficacy of CTLA4 therapy (P <0.05). These results indicated that CD14 expression was strongly correlated with the GC immune response. A noticeable increase in CD14 levels was observed in MNU-induced GC animals, cell models, and GC patients. In addition, the number of M2 macrophages was increased in MNU-induced GC mice. Conclusion: Reducing CD14 expression may increase the survival rate of GC patients through the modulation of immune responses. The complex mechanism of CD14's influence on prognosis deserves further investigation.

Peptide‑based therapeutic strategies for glioma: Current state and prospects

Glioma is a prevalent form of primary malignant central nervous system tumor, characterized by its cellular invasiveness, rapid growth, and the presence of the blood-brain barrier (BBB)/blood-brain tumor barrier (BBTB). Current therapeutic approaches, such as chemotherapy and radiotherapy, have shown limited efficacy in achieving significant antitumor effects. Therefore, there is an urgent demand for new treatments. Therapeutic peptides represent an innovative class of pharmaceutical agents with lower immunogenicity and toxicity. They are easily modifiable via chemical means and possess deep tissue penetration capabilities which reduce side effects and drug resistance. These unique pharmacokinetic characteristics make peptides a rapidly growing class of new therapeutics that have demonstrated significant progress in glioma treatment. This review outlines the efforts and accomplishments in peptide-based therapeutic strategies for glioma. These therapeutic peptides can be classified into four types based on their anti-tumor function: tumor-homing peptides, inhibitor/antagonist peptides targeting cell surface receptors, interference peptides, and peptide vaccines. Furthermore, we briefly summarize the results from clinical trials of therapeutic peptides in glioma, which shows that peptide-based therapeutic strategies exhibit great potential as multifunctional players in glioma therapy.

Suppressing, stimulating and/or inhibiting: The evolving management of HCC patient after liver transplantation

Liver transplantation (LT) is a curative strategy for hepatocellular carcinoma (HCC), but the risk of HCC recurrence remains a challenging problem. In patients with HCC recurrence after LT (HCC-R_LT), the locoregional and surgical approaches are complex, and the guidelines do not report evidence-based strategies for the management of immunosuppression. In recent years, immunotherapy has become an effective option for patients with advanced HCC in pre-transplant settings. However, due to the risk of potentially fatal allograft rejection, the use of immunotherapy is avoided in post-transplant settings. Combining immunosuppressants with immunotherapy in transplant patients is also challenging due to the complex tumor microenvironment and immunoreactivity. The fear of acute liver rejection and the lack of predictive factors hinder the successful clinical application of immunotherapy for post-liver transplantation HCC recurrence. This review aims to comprehensively summarize the risk of HCC-R_LT, the available evidence for the efficacy of immunotherapy in patients with HCC-R_LT, and the clinical issues regarding the innovative management of this patient population.

Exploring the mediating role of immune cells in the pathogenesis of IgA nephropathy through the inflammatory axis of gut microbiota from a genomic perspective

IgA nephropathy (IgAN) is a chronic glomerular disease characterized by the deposition of IgA antibodies in the kidney's mesangium. Its pathogenesis involves genetic, immune, and environmental factors, particularly within the mucosal immune system and gut microbiota. Immune cells play a central role in mediating these processes, which this study investigates using Mendelian Randomization (MR) to explore causal relationships among gut microbiota, inflammatory markers, blood cells, and immune cells in IgAN pathogenesis. We conducted a two-sample MR analysis using Genome-Wide Association Study (GWAS) summary data to assess the causal effects of gut microbiota, inflammatory markers, and blood cell traits on IgAN. Data sources included the FinnGen dataset for IgAN and relevant GWAS datasets for immune traits, blood cells, and inflammatory markers. Inverse variance weighting (IVW) was the primary MR method, supported by sensitivity analyses. We particularly examined the mediation effect of immune cells on these exposures' influence on IgAN. Significant associations were found between several factors and IgAN. Gut microbiota traits, such as Firmicutes E and Sporomusales, increased IgAN risk, while Citrobacter A and Herbinix reduced it. Inflammatory markers, including Interleukin-10 and Fibroblast Growth Factor 23, promoted IgAN onset. Blood cell traits like red blood cell perturbation response increased risk, while monocyte perturbation response was protective. Immune traits played a key mediating role, with Transitional %B cells reducing IgAN risk and CD28- CD25 +  + CD8br %T cells increasing it. This study highlights the pivotal mediating role of immune cells in the interactions between gut microbiota, inflammatory markers, and IgAN risk. These findings identify potential biomarkers and therapeutic targets, providing new insights into the immune mechanisms underlying IgAN and opportunities for intervention.

Immunohistochemical Expression of Programmed Death-Ligand 1 and Cytotoxic T-Lymphocyte Antigen-4 in Canine Cutaneous Mast Cell Tumours

Mast cell tumours (MCTs) are the most frequent cutaneous neoplasia of the dog, and they have very variable biological behaviour and survival times. Surgery is still the best treatment, and despite the several adjuvant therapies described, many cases are very aggressive and resistant to these treatments making it urgent to find new therapeutic targets. Nowadays, immunotherapy targeting immune checkpoints has been described as a complementary treatment for several human cancers, but it is still very scarcely studied in veterinary medicine. Therefore, this study aimed to investigate the expression of the checkpoint proteins programmed death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte antigen-4 (CTLA-4) to evaluate their potential as therapeutic targets for MCT. Through immunohistochemical study, it was analysed the expression of PD-L1 and CTLA-4 in 74 MCT cases from the archive of the Veterinary Pathology Laboratory of the University of Porto (LabPatVet). Tumour size, histological grade, ki-67 proliferation index, mitotic count and presence of metastatic disease were also assessed. Most of the cases expressed both immune checkpoints in neoplastic cells. There was a statistically significant inverse association between the expression of CTLA-4 and MCT grade (p < 0,001) and mitotic count (p < 0.001). PD-L1 was significantly and negatively related to HG (p = 0.004), and tumour size (р = 0.014). Tumour size, histological grade and mitotic count were positively associated with metastatic disease. Additionally, it was observed that the expression of PD-L1 and CTLA-4 was interrelated (p < 0.001). This study demonstrated that MCT cells express both PD-L1 and CTLA-4 and that their expression was associated with MCT prognostic factors.

Structural investigation of an RNA device that regulates PD-1 expression in mammalian cells

Synthetic RNA devices are engineered to control gene expression and offer great potential in both biotechnology and clinical applications. Here, we present multidisciplinary structural and biochemical data for a tetracycline (Tc)-responsive RNA device (D43) in both ligand-free and bound states, providing a structure-dynamical basis for signal transmission. Activation of self-cleavage is achieved via ligand-induced conformational and dynamical changes that stabilize the elongated bridging helix harboring the communication module, which drives proper coordination of the catalytic residues. We then show the utility of CRISPR-integrated D43 in EL4 lymphocytes to regulate programmed cell death protein 1 (PD-1), a key receptor of immune checkpoints. Treatment of these cells with Tc showed a dose-dependent reduction in PD-1 by immunostaining and a decrease in messenger RNA levels by quantitative PCR as compared with wild type. PD-1 expression was recoverable upon removal of Tc. These results provide mechanistic insight into RNA devices with potential for cancer immunotherapy or other applications.

E-twenty-six-specific sequence variant 5 (ETV5) facilitates hepatocellular carcinoma progression and metastasis through enhancing polymorphonuclear myeloid-derived suppressor cell (PMN-MDSC)-mediated immunosuppression

BACKGROUND

Despite the success of immune checkpoint blockade, a lack of understanding of the hepatocellular carcinoma (HCC) immune microenvironment impedes its development.

OBJECTIVE

We aim to elucidate the essential function of E-twenty-six-specific sequence variant 5 (ETV5) in regulating the immune microenvironment in HCC.

DESIGN

Humanised mouse models, murine orthotopic models and diethylnitrosamine/carbon tetrachloride (DEN/CCl4)-induced HCC models were used to examine the function of ETV5. The downstream targets of ETV5 were screened using chromatin immunoprecipitation sequencing, CUT&Tag and RNA sequencing. Immune cells were examined using flow cytometry and immunofluorescence. S100 calcium-binding protein A9 (S100A9) was targeted by neutralising antibodies.

RESULTS

Overexpression of ETV5 in HCC cells facilitated HCC metastasis and immune escape by recruiting and enhancing the immunosuppressive capabilities of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs). Mechanistically, ETV5 transactivated programmed death ligand 1 (PD-L1) and S100A9 expression. Inhibition of S100A9 or myeloid-specific knockout of toll-like receptor 4 (TLR4)/receptor for advanced glycation endproducts (RAGE), the receptors of S100A9, impeded ETV5-induced PMN-MDSC recruitment. Meanwhile, S100A9 within the tumour microenvironment elevated ETV5 expression via the extracellular signal-regulated kinase (ERK)/nuclear factor-kappa B pathway. Additionally, ETV5 transcriptionally upregulated PD-L1 in MDSCs as well, thereby augmenting their immunosuppressive functions. Myeloid-specific Etv5 knockout attenuated HCC progression. We developed monoclonal neutralising-S100A9 antibodies that effectively inhibited ETV5-mediated PMN-MDSC infiltration. Synergistic application of anti-S100A9 or TLR4/RAGE inhibitors with anti-PD-L1 therapy significantly suppressed ETV5-mediated HCC progression.

CONCLUSION

ETV5 facilitates HCC progression and metastasis by promoting the recruitment, infiltration and activation of PMN-MDSCs. Synergistic application of anti-S100A9 or TLR4/RAGE inhibitors with anti-PD-L1 therapy holds great promise as an effective combinational treatment strategy for ETV5-positive HCC.

Enhanced thrombopoiesis supplies PD-L1 to circulating immune cells via the generation of PD-L1-expressing platelets in patients with lung cancer

BACKGROUND

The increased expression of programmed cell death ligand 1 (PD-L1) on a subset of immune cells in the peripheral blood has been frequently observed in patients with cancer, suggesting a relationship with PD-L1 expression in tumor tissues. In this study, we investigated the mechanisms underlying PD-L1 expression on various types of immune cells in the peripheral blood of patients with cancer.

METHODS

PD-L1 expression on various immune cell populations was analyzed in peripheral blood mononuclear cells of 112 patients with non-small cell lung cancer (NSCLC) using flow cytometry. A mouse model of X-ray-induced acute thrombocytopenia was used to investigate the relationship between thrombopoiesis and PD-L1-expressing platelet generation. The clinical significance of PD-L1-expressing platelets was analyzed in a cohort of patients with stage IV NSCLC who received a combination of anti-programmed cell death 1 (PD-1) therapy and chemotherapy.

RESULTS

All immune cell populations, including monocytes, T cells, B cells, and NK cells, showed higher PD-L1 expression in patients with cancer than in healthy controls. However, this increased frequency of PD-L1-expressing cells was not attributed to the expression of the cells themselves. Instead, it was entirely dependent on the direct interaction of the cells with PD-L1-expressing platelets. Notably, the platelet-dependent acquisition of PD-L1 on circulating immune cells of patients with lung cancer was observed in various other cancer types and was mechanistically associated with a surge in thrombopoiesis, resulting in the increased production of PD-L1-expressing reticulated platelets. Clinically, patients with enhanced thrombopoiesis and concurrently high PD-L1-expressing platelets exhibited a better response to anti-PD-1 therapy.

CONCLUSIONS

These findings highlight the role of tumor-associated thrombopoiesis in generating PD-L1-expressing platelets that may serve as a resource for PD-L1-positive cells in the circulation and act as a predictive biomarker for anti-PD-1/PD-L1 therapy.

ENTPD8 overexpression enhances anti-PD-L1 therapy in hepatocellular carcinoma via miR-214-5p inhibition

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related deaths globally, with poor prognosis due to late diagnosis and limited treatment options. In this study, we evaluated the expression of ectonucleoside triphosphate diphosphohydrolase 8 (ENTPD8) in HCC tissues and its clinical significance. Immunohistochemistry, The Cancer Genome Atlas (TCGA) data, and single-cell expression analysis revealed reduced ENTPD8 levels in liver cancer compared to adjacent tissues, with ENTPD8 primarily expressed in tumor cells within the tumor tissue. In vitro assays demonstrated that ENTPD8 inhibits HCC cell proliferation, invasion, and migration. Mechanistically, ENTPD8 regulates programmed death-ligand 1 (PD-L1) expression through miR-214-5p modulation. In vivo, ENTPD8 overexpression combined with anti-PD-L1 treatment enhanced therapeutic efficacy in HCC mouse models. These findings suggest that ENTPD8 may serve as a prognostic marker and therapeutic target for HCC, offering potential strategies for improving treatment outcomes.

Wnt-Activated Immunoregulatory Myeloid Cells Prevent Relapse in Experimental Autoimmune Encephalomyelitis and Offer a Potential Therapeutic Strategy for Multiple Sclerosis

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) characterized by recurrent inflammatory relapses and neurodegeneration. Myeloid cells play a critical role in shaping the inflammatory environment and influencing disease progression. Here, we demonstrate that activation of the Wnt signaling pathway reprograms myeloid cells into an immunoregulatory phenotype, leading to reduced neuroinflammation and disease severity. Using both experimental autoimmune encephalomyelitis (EAE) and human-derived myeloid cells, we show that Wnt agonist treatment promotes the expression of inhibitory molecules such as PD-L1 and PD-L2, suppressing pro-inflammatory responses. In the chronic and relapsing-remitting EAE models, Wnt activation significantly reduced disease severity, immune cell infiltration into the CNS, and pathogenic T cell responses. Notably, in relapsing-remitting EAE, Wnt treatment prevented new relapses in a PD-L1-dependent manner, highlighting the crucial role of myeloid cell-mediated immune regulation. These findings reveal a previously unrecognized role for Wnt signaling in myeloid cell immunoregulation and suggest that targeting this pathway could provide a novel therapeutic strategy for MS and other autoimmune diseases.

Small molecule-mediated inhibition of the oxidoreductase ERO1A restrains aggressive breast cancer by impairing VEGF and PD-L1 in the tumor microenvironment

Cancer cells adapt to harsh environmental conditions by inducing the Unfolded Protein Response (UPR), of which ERO1A is a mediator. ERO1A aids protein folding by acting as a protein disulfide oxidase, and under cancer-related hypoxia conditions, it favors the folding of angiogenic VEGFA, leading tumor cells to thrive and spread. The upregulation of ERO1A in cancer cells, oppositely to the dispensability of ERO1A activity in healthy cells, renders ERO1A a perfect target for cancer therapy. Here, we report the upregulation of ERO1A in a cohort of aggressive triple-negative breast cancer (TNBC) patients in which ERO1A levels correlate with a higher risk of breast tumor recurrence and metastatic spread. For ERO1A target validation and therapy in TNBC, we designed new ERO1A inhibitors in a structure-activity campaign of the prototype EN460. Cell-based screenings showed that the presence of the Micheal acceptor in the compound is necessary to engage the cysteine 397 of ERO1A but not sufficient to set out the inhibitory effect on ERO1A. Indeed, the ERO1 inhibitor must adopt a non-coplanar rearrangement within the ERO1A binding site. I2 and I3, two new EN460 analogs with different phenyl-substituted moieties, efficiently inhibited ERO1A, blunting VEGFA secretion. Accordingly, in vitro assays to measure ERO1A engagement and inhibition confirmed that I2 and I3 bind ERO1A and restrain its activity with a IC50 in a low micromolar range. EN460, I2 and I3 triggered breast cancer cytotoxicity while specifically inhibiting ERO1A in a dose-dependent manner. I2 more efficiently impaired cancer-relevant features such as VEGFA secretion and related cell migration. I2 also acted on the tumor microenvironment and viability of xenografts and syngeneic TNBC. Thus, small molecule-mediated ERO1A pharmacological inhibition is feasible and promises to lead to effective therapy for the still incurable TNBC.

Molecular biology of the novel anticancer medications: a focus on kinases inhibitors, biologics and CAR T-cell therapy

INTRODUCTION

Cancer treatment underwent significant changes in the last few years with the introduction of novel treatments targeting the immune system.

OBJECTIVES

The objective of this review is to discuss novel anticancer drugs including kinase inhibitors, biologics and cellular therapy with CAR-T cells.

METHODS

Most recent research articles were extracted from PubMed using keywords such as "kinases inhibitors", "CAR-T cell therapy".

RESULTS AND DISCUSSION

The number of kinase inhibitors is significantly increasing due to their demonstrated effectiveness in combination with biologics. CAR-T represented a major breakthrough in the field. Also, it focused on their mechanisms of action and the rational of their use either alone or in combination in relation to their modes of action.

Simultaneous Induction of Immunogenic Pyroptosis and PD-L1 Downregulation by One Single Photosensitizer for Synergistic Cancer Photoimmunotherapy

Pyroptosis, an excellent form of immunogenic cell death that can effectively activate antitumor immune responses, is attracting considerable interest as a promising approach for cancer immunotherapy. Immunogenic pyroptosis can recruit and stimulate dendritic cells to provoke further activation and tumor infiltration of T cells by releasing danger-associated molecular patterns, thus improving the tumor response to PD-1/PD-L1 checkpoint blockade immunotherapy. Here, we report the discovery of a bifunctional photosensitizer Nile Violet that can simultaneously trigger caspase-3/GSDME-mediated immunogenic pyroptosis and PD-L1 downregulation for cancer photoimmunotherapy. It was shown that this synergistic therapeutic strategy significantly inhibited tumor growth by triggering a systemic antitumor immune response. This work highlights the potential of inducing immunogenic pyroptosis and PD-L1 downregulation for synergistic tumor ablation via a single agent.

Human cytomegalovirus tegument protein UL23 promotes gastric cancer immune evasion by facilitating PD-L1 transcription

Immune checkpoint therapy targeting PD-1/PD-L1 has shown promise in treating tumors, however, its clinical benefits are limited to a subset of gastric cancer (GC) patients. Recent research has highlighted a the correlation between PD-L1 expression and the clinical efficacy of anti-PD-1/PD-L1 therapies. Human cytomegalovirus (HCMV) has been implicated in GC, but its specific role in modulating this disease remains elusive. In this study, we analyzed clinical tissue samples using bioinformatics and real-time quantitative polymerase chain reaction (RT-qPCR). We found that GC tissues infected with HCMV presented higher PD-L1 expression compared to those without virus. Furthermore, we demonstrated that HCMV infection enhances PD-L1 expression in GC cells. Cytotoxicity assays revealed that HCMV modulates cancer immune responses via the PD-1/PD-L1 pathway. Mechanistically, we showed that HCMV activates the PI3K-Akt signaling cascade and modulates PD-L1 expression through its tegument protein UL23. Functionally, increased UL23 expression leads to elevated PD-L1 levels, which diminishes tumor cell sensitivity to T-cell-mediated cytotoxicity and triggers T-cell apoptosis. Additionally, in vivo experiments revealed that UL23-induced PD-L1 upregulation inhibits CD8+ T-cell infiltration and reduces the expression of inflammatory factors in tumor microenvironment, ultimately weakening antitumor immunity. Our findings reveal a novel mechanism whereby HCMV and its tegument protein UL23 contribute to cancer immunosuppression through the regulation of PD-L1 expression. This discovery may serve as a potential therapeutic target for enhancing the efficacy of cancer immunotherapy.

Apatinib Degrades PD-L1 and Reconstitutes Colon Cancer Microenvironment via the Regulation of Myoferlin

BACKGROUND

For most colorectal cancer (CRC) patients, expanding the benefits of immunotherapy, particularly through blocking programmed cell death-1 (PD-1) and its ligand (PD-L1), is crucial, especially in cases with limited response to neoadjuvant therapy. This study investigates the role of Myoferlin (MYOF) as a novel target in CRC immunotherapy.

METHODS

Human CRC cell lines (RKO, HCT116), normal intestinal epithelial cells (HIEC-6), and the murine CRC cell line MC38 were used to study the effects of apatinib and MYOF in CRC cells. RNA sequencing, the CPTAC and TCGA databases, and other molecular and cellular methods were applied to disclose the mechanisms involved. A series of mouse models were established to assess the effects of apatinib and MYOF knockdown on tumor progression, immune cell infiltration, and immune checkpoint protein response.

RESULTS

We found that MYOF is overexpressed in CRC and linked to immune cell infiltration and checkpoint expression. Suppression of MYOF expression significantly inhibited CRC cell proliferation and migration, as well as reduced PD-L1 protein levels. Integrative analysis showed that apatinib modulates MYOF expression via VEGFR2, resulting in decreased PD-L1 expression, increased CD8+ T cell infiltration, and reduced pro-tumor M2 macrophages. Animal experiments further revealed that apatinib treatment or MYOF knockdown enhanced the efficacy of immune checkpoint blockade (ICB) in CRC.

CONCLUSIONS

These findings highlight novel antitumor mechanisms of MYOF and suggest that combining apatinib with ICB therapy may improve CRC treatment outcomes, offering a promising strategy to enhance immune responses.

Pre-injection of exosomes can significantly suppress ovarian cancer growth by activating the immune system in mice

As a type of "cold tumor" with limited immune cell infiltration, ovarian cancer has historically shown limited efficacy in immunotherapy. In this study, we report that exosomes from ovarian cancer can specifically target omentum which is the predilection site for ovarian cancer to metastasize and combat subsequently implanted tumor. Furthermore, we found a substantial increase in the proportion of CD3 + T cells, particularly CD8 + T cells, within the omental tissue where exosomes homed. This increase was accompanied by a significant enhancement in granzyme B levels within CD8 + T cells. Additionally, there was a notable elevation in the concentration of interferon-gamma (IFN-γ) in peripheral blood. In vitro results indicated that exosomes could be internalized by dendritic cells (DCs), promote DC differentiation, and subsequently induce the production of granzyme B and IFN-γ in T cells. Surprisingly, we also observed high expression of programmed death ligand 1 (PD-L1) in the omentum. Therefore, we discovered whether combining PD-L1 blockade led to further tumor regression. However, although the combination group showed complete tumor regression, this difference did not reach statistical significance. But in general, we emphasize that in the case of pre-injection, exosomes have great potential to combat the famous "cold tumor", ovarian cancer, via targeting omentum and activating anti-tumor immunity, offering a novel avenue for overcoming ovarian cancer.

Natural products targeting RAS by multiple mechanisms and its therapeutic potential in cancer: An update since 2020

RAS proteins, as pivotal signal transduction molecules, are frequently mutated and hyperactivated in various human cancers, closely associated with tumor cell proliferation, survival, and metastasis. Despite extensive research on RAS targeted therapies, developing effective RAS inhibitors remains a significant challenge. Natural products, endowed with unique chemical structures and diverse biological activities through long-term natural selection, have emerged as a vital resource for discovering novel RAS-targeted therapeutic drugs. This review focuses on the latest advancements in targeting RAS with natural products and categorizes these natural products based on their mechanisms of action. Additionally, we discuss the challenges faced by these natural products during clinical translation, including issues related to pharmacokinetics. Strategies such as combination therapy, structural optimization, and drug delivery systems are anticipated to enhance efficacy and overcome these challenges.

RBM15 Drives Breast Cancer Cell Progression and Immune Escape via m6A-Dependent Stabilization of KPNA2 mRNA

BACKGROUND

Breast cancer is the most frequently diagnosed cancer among women worldwide with high morbidity and mortality. Previous studies have indicated that RNA-binding motif protein-15 (RBM15), an N6-methyladenosine (m6A) writer, is implicated in the growth of breast cancer cells. Herein, we aimed to explore the function and detailed mechanism of RBM15 in breast cancer.

METHODS

In this research, UALCAN databases were applied to analyze the expression of RBM15 or Karyopherin-2 alpha (KPNA2) in BRCA. RBM15 and KPNA2 mRNA levels were determined using real-time quantitative polymerase chain reaction (RT-qPCR) assay. RBM15, KPNA2, and Programmed cell death ligand 1 (PD-L1) protein levels were measured using western blot. Cell proliferation, migration, and invasion were assessed using 5-ethynyl-2'-deoxyuridine (EdU) and Transwell assays. The biological role of RBM15 on breast cancer tumor growth was verified using the xenograft tumor model in vivo. Effects of breast cancer cells on the proliferation and apoptosis of CD8+ T cells were analyzed using flow cytometry. Interaction between RBM15 and KPNA2 was validated using methylated RNA immunoprecipitation (MeRIP) and dual-luciferase reporter assays.

RESULTS

RBM15 and KPNA2 were highly expressed in breast cancer tissues and cell lines. Furthermore, RBM15 silencing might suppress breast cancer cell proliferation, migration, invasion, and lymphocyte immunity in vitro, as well as block tumor growth in vivo. At the molecular level, RBM15 might improve the stability and expression of KPNA2 mRNA via m6A methylation.

CONCLUSION

RBM15 might contribute to the malignant progression and immune escape of breast cancer cells partly by modulating the stability of KPNA2 mRNA, providing a promising therapeutic target for breast cancer.

Preclinical evaluation of bozepinib in bladder cancer cell lines: modulation of the NPP1 enzyme

Bladder cancer (BC) is the most common cancer of the urinary tract. Bozepinib (BZP), a purine-derived molecule, is a potential compound for the treatment of cancer. Purinergic signaling consists of the activity of nucleosides and nucleotides present in the extracellular environment, modulating a variety of biological actions. In cancer, this signaling is mainly controlled by the enzymatic cascade involving the NTPDase/E-NPP family and ecto-5'-nucleotidase/CD73, which hydrolyze extracellular adenosine triphosphate (ATP) to adenosine (ADO). The aim of this work is to evaluate the activity of BZP in the purinergic system in BC cell lines and to compare its in vitro antitumor activity with cisplatin, a chemotherapeutic drug widely used in the treatment of BC. In this study, two different BC cell lines, grade 1 RT4 and the more aggressive grade 3 T24, were used along with a human fibroblast cell line MRC-5, a cell used to predict the selectivity index (SI). BZP shows strong antitumor activity, with notable IC50 values (8.7 ± 0.9 µM for RT4; 6.7 ± 0.7 µM for T24), far from the SI for cisplatin (SI for BZP: 19.7 and 25.7 for RT4 and T24, respectively; SI for cisplatin: 1.7 for T24). BZP arrests T24 cells in the G2/M phase of the cell cycle, inducing early apoptosis. Moreover, BZP increases ATP and ADP hydrolysis and gene/protein expression of the NPP1 enzyme in the T24 cell line. In conclusion, BZP shows superior activity compared to cisplatin against BC cell lines in vitro.

A new enhancer for anti-PD-1/PD-L1 immunotherapy: PCSK9 inhibition

Anti-programmed cell death protein 1 (PD-1)/PD-1 ligand 1 (PD-L1) immunotherapy has shown promising results in cancer treatment, improving clinical outcomes and prolonging patient survival. However, most patients exhibit low response rates to PD-1/PD-L1 blockade, highlighting the urgent need for new enhancers. Increasing data now demonstrate that inhibiting proprotein convertase subtilisin/kexin type 9 (PCSK9), a serine proteinase, can enhance the antitumor efficacy of anti-PD-1/PD-L1 immunotherapy.

Elevated Neutrophil-to-Lymphocyte Ratio Correlates With Liver Metastases and Poor Immunotherapy Response in Stage IV Melanoma

BACKGROUND AND OBJECTIVES

Immune checkpoint inhibition (ICI) has revolutionized treatment for metastasized melanoma, but many patients remain unresponsive. Concerning potential adverse events, reliable biomarkers to predict ICI response are needed. In this context, neutrophil-to-lymphocyte ratio (NLR) and derived NLR (dNLR) have emerged. Liver metastases also limit ICI efficacy, correlating with diminished overall survival (OS) and progression-free survival (PFS) and may siphon activated T cells from the systemic circulation, creating an 'immune desert state'. We evaluated the predictive role of NLR and dNLR for ICI response and the impact of liver metastases on systemic immunity and treatment efficacy.

PATIENTS AND METHODS

In this single-center retrospective study, we included 141 stage IV melanoma patients undergoing ICI. NLR and dNLR were calculated from absolute neutrophil count, absolute lymphocyte count, and white blood cell count.

RESULTS

Elevated NLR and dNLR were associated with poor response to ICI and inferior PFS. Patients with liver metastases exhibited higher NLR and dNLR levels and showed diminished response to ICI.

CONCLUSIONS

Elevated baseline NLR and dNLR predict poor response to ICI and PFS in stage IV melanoma. Liver metastases are negative predictors for ICI response, with associated higher NLR and dNLR levels potentially contributing to therapy resistance.

Co-Delivery of aPD-L1 and CD73 Inhibitor Using Calcium Phosphate Nanoparticles for Enhanced Melanoma Immunotherapy with Reduced Toxicity

Melanoma, a malignant skin tumor, presents significant treatment challenges, particularly in unresectable and metastatic cases. While immune checkpoint inhibitors (ICIs) targeting PD-1/PD-L1 have brought new hope, their efficacy is limited by low response rates and significant immune-mediated adverse events (irAEs). Through multi-omics data analysis, it is discovered that the spatial co-localization of CD73 and PD-L1 in melanoma correlates with improved progression-free survival (PFS), suggesting a synergistic potential of their inhibitors. Building on these insights, a novel therapeutic strategy using calcium phosphate (CaP) nanoparticles is developed for the co-delivery of aPD-L1 and APCP, a CD73 inhibitor. These nanoparticles, constructed via a biomineralization method, exhibit high drug-loading capacity and pH-responsive drug release. Compared to free aPD-L1, the CaP-delivered aPD-L1 effectively avoids systemic side effects while significantly enhancing anti-tumor efficacy, surpassing even a 20-fold dose of free aPD-L1. Furthermore, the co-delivery of aPD-L1 and APCP via CaP nanoparticles demonstrates a synergistic anti-tumor effect, with substantial immune activation and prevention of tumor recurrence through immune memory effects. These findings suggest that the co-delivery of aPD-L1 and APCP using CaP nanoparticles is a promising approach for improving melanoma immunotherapy, achieving enhanced efficacy and reduced toxicity.

PD-1 blockade treatment in melanoma: Mechanism of response and tumor-intrinsic resistance

Malignant melanoma is characterized by high immunogenicity, genetic heterogeneity, and diverse pathological manifestations, affecting both skin and mucosa over the body. Pembrolizumab and nivolumab, both anti-PD-1 monoclonal antibodies, were approved by the US FDA for unresectable or metastatic melanoma in 2011 and 2014, respectively, with enduring and transformative outcomes. Despite marked clinical achievements, only a subset of patients manifested a complete response. Approximately 55% of melanoma patients exhibited primary resistance to PD-1 antibodies, with nearly 25% developing secondary resistance within 2 years of treatment. Thus, there is a critical need to comprehensively elucidate the mechanisms underlying the efficacy and resistance to PD-1 blockade. This review discusses the fundamental mechanisms of PD-1 blockade, encompassing insights from T cells and B cells, and presents resistance to anti-PD-1 with a particular focus on tumoral-intrinsic mechanisms in melanoma.

Tumor-Targeted Catalytic Immunotherapy

Cancer immunotherapy holds significant promise for improving cancer treatment efficacy; however, the low response rate remains a considerable challenge. To overcome this limitation, advanced catalytic materials offer potential in augmenting catalytic immunotherapy by modulating the immunosuppressive tumor microenvironment (TME) through precise biochemical reactions. Achieving optimal targeting precision and therapeutic efficacy necessitates a thorough understanding of the properties and underlying mechanisms of tumor-targeted catalytic materials. This review provides a comprehensive and systematic overview of recent advancements in tumor-targeted catalytic materials and their critical role in enhancing catalytic immunotherapy. It highlights the types of catalytic reactions, the construction strategies of catalytic materials, and their fundamental mechanisms for tumor targeting, including passive, bioactive, stimuli-responsive, and biomimetic targeting approaches. Furthermore, this review outlines various tumor-specific targeting strategies, encompassing tumor tissue, tumor cell, exogenous stimuli-responsive, TME-responsive, and cellular TME targeting strategies. Finally, the discussion addresses the challenges and future perspectives for transitioning catalytic materials into clinical applications, offering insights that pave the way for next-generation cancer therapies and provide substantial benefits to patients in clinical settings.

Epstein-Barr virus-infected nasopharyngeal carcinoma therapeutics: oncoprotein targets and clinical implications

Nasopharyngeal carcinoma (NPC) is a distinctive epithelial cancer closely associated with Epstein-Barr Virus (EBV) infection, posing significant challenges in diagnosis and treatment due to its resistance to conventional therapies and high recurrence rates. Current therapies, including radiotherapy and chemotherapy, exhibit limited efficacy, particularly in recurrent or metastatic cases, highlighting the urgent need for novel therapeutic strategies. Targeting EBV oncoproteins, such as Epstein-Barr Virus encoded Nuclear Antigen 1 (EBNA1), Latent Membrane Protein 1 (LMP1), and Latent Membrane Protein 2 (LMP2), presents a promising therapeutic avenue in NPC treatment. This review discusses the latest advancements in drug discovery targeting EBV oncoproteins, emphasizing the identification of inhibitors for specific functional regions of oncoproteins EBNA1, LMP1, and LMP2. Particular attention is given to the molecular mechanisms of these inhibitors and their preclinical or clinical potential in treating EBV-positive NPC. These developments highlight a promising future for targeted therapies in improving outcomes for NPC patients.

Preclinical evaluation and preliminary clinical study of 68Ga-NODAGA-NM-01 for PET imaging of PD-L1 expression

BACKGROUND

Programmed cell death 1/programmed death ligand-1 (PD-L1)-based immune checkpoint blockade is an effective treatment approach for non-small-cell lung cancer (NSCLC). However, immunohistochemistry does not accurately or dynamically reflect PD-L1 expression owing to its spatiotemporal heterogeneity. Herein, we assessed the feasibility of using a 68Ga-labeled anti-PD-L1 nanobody, 68Ga-NODAGA-NM-01, for PET imaging of PD-L1.

METHODS

Micro-PET/CT and biodistribution studies were performed on PD-L1-positive and -negative tumor-bearing mice. Additionally, a preliminary clinical study was performed on two patients with NSCLC. NM-01 was radiolabeled with 68Ga without further purification under mild conditions.

RESULTS

68Ga-NODAGA-NM-01 exhibited radiochemical purity (> 98%), high stability in vitro, and rapid blood clearance in vivo. Specific accumulation of 68Ga-NODAGA-NM-01 was observed in PD-L1-positive tumor-bearing mice, with a good tumor-to-background ratio 0.5h post-injection. Furthermore, 68Ga-NODAGA-NM-01 PET/CT imaging was found to be safe with no adverse events and distinct uptake in primary and metastatic lesions of the PD-L1-positive patient, with a higher maximal standardized uptake value than that in lesions of the PD-L1-negative patient 1h post-injection.

CONCLUSIONS

68Ga-NODAGA-NM-01 can be prepared using a simple method under mild conditions and reflect PD-L1 expression in primary and metastatic lesions. However, our findings need to be confirmed in a large cohort.

TRIAL REGISTRATION

NCT02978196. Registered February 15, 2018.

Brucella abortus impairs T lymphocyte responsiveness by mobilizing IL-1RA-secreting omental neutrophils

Immune evasion strategies of Brucella, the etiologic agent of brucellosis, a global zoonosis, remain partially understood. The omentum, a tertiary lymphoid organ part of visceral adipose tissue, has never been explored as a Brucella reservoir. We report that B. abortus infects and replicates within murine omental macrophages. Throughout the chronic phase of infection, the omentum accumulates macrophages, monocytes and neutrophils. The maintenance of PD-L1+Sca-1+ macrophages, monocytes and neutrophils in the omentum depends on the wadC-encoded determinant of Brucella LPS. We demonstrate that PD-L1+Sca-1+ murine omental neutrophils produce high levels of IL-1RA leading to T cell hyporesponsiveness. These findings corroborate brucellosis patient analysis of whole blood displaying upregulation of PDL1 and Ly6E genes, and of serum exhibiting high levels of IL-1RA. Overall, the omentum, a reservoir for B. abortus, promotes bacterial persistence and causes CD4+ and CD8+ T cell immunosuppression by IL-1RA secreted by PD-L1+Sca-1+ neutrophils.

A risk signature constructed by Tregs-related genes predict the clinical outcomes and immune therapeutic response in kidney cancer

Regulatory T cells (Tregs) have been found to be related to immune therapeutic resistance in kidney cancer. However, the potential Tregs-related genes still need to be explored. Our study found that patients with high Tregs activity show poor prognosis. Through co-expression and differential expression analysis, we screened several Tregs-related genes (KTRGs) in kidney renal clear cell carcinoma. We further conducted the univariate Cox regression analysis and determined the prognosis-related KTRGs. Through the machine learning algorithm-Boruta, the potentially important KTRGs were screened further and submitted to construct a risk model. The risk model could predict the prognosis of RCC patients well, high risk patients show a poorer outcomes than low risk patients. Multivariate Cox regression analysis reveals that risk score is an independent prognostic factor. Then, the nomogram model based on KTRG risk score and other clinical variables was further established, which shows a high predicted accuracy and clinical benefit based on model validation methods. In addition, we found EMT, JAK/STAT3, and immune-related pathways highly enriched in high risk groups, while metabolism-related pathways show a low enrichment. Through analyzing two other external immune therapeutic datasets, we found that the risk score could predict the patient's immune therapeutic response. High-risk groups represent a worse therapeutic response than low-risk groups. In summary, we identified several Tregs-related genes and constructed a risk model to predict prognosis and immune therapeutic response. We hope these organized data can provide a theoretical basis for exploring potential Tregs' targets to synergize the immune therapy for RCC patients.

ArfGAP with the SH3 Domain, Ankyrin Repeat and PH Domain 1 Inversely Regulates Programmed Death-Ligand 1 Through Negative Feedback of Phosphorylated Epithelial Growth Factor Receptor and Activation of Nuclear Factor-Kappa B in Non-Small Cell Lung Cancer

Background

Signaling pathways centered on the G-protein ADP-ribosylation factor 6 (Arf6) and its downstream effector ArfGAP with the SH3 Domain, Ankyrin Repeat and PH Domain 1 (AMAP1) drive cancer invasion, metastasis, and therapy resistance. The Arf6-AMAP1 pathway has been reported to promote receptor recycling leading to programmed cell death-ligand 1 (PD-L1) overexpression in pancreatic ductal carcinoma. Moreover, AMAP1 regulates of nuclear factor-kappa B (NF-κB), which is an important molecule in inflammation and immune activation, including tumor immune interaction through PD-L1 regulation. In this study, we investigated the function of AMAP1 on PD-L1 expression using lung cancer cells.

Methods

We used two non-small cell lung cancer cell lines. Protein expression was evaluated by Western blotting. AMAP1 and NF-kB expression were reduced by conventional siRNA methods, and osimertinib was used as an epithelial growth factor receptor (EGFR) inhibitor. Multiple analysis of receptor tyrosine kinases (RTKs) was conducted using a semi-comprehensive RTKs assay.

Results

We found that AMAP1 inversely regulated PD-L1 expression. Based on these results, we examined the activation levels of RTKs associated with both AMAP1 and PD-L1. Following a semi-comprehensive phosphorylated RTK assay, we observed the upregulation of phosphorylated EGFR (pEGFR) led by the downregulation of AMAP1. The inhibition of pEGFR by osimertinib downregulates PD-L1 expression. We investigated the relationships between AMAP1, NF-κB, and PD-L1 expression. AMAP1 knockdown upregulated the expression of both NF-κB and PD-L1. Subsequently, NF-κB knockdown downregulated PD-L1 levels, while double knockdown of AMAP1 and NF-κB, restored PD-L1 expression.

Conclusion

AMAP1 may inversely regulate PD-L1 through negative feedback of pEGFR and activation of NF-κB in NSCLC cell lines.

Progress and prospects of the combination of BMI1-targeted therapy and immunotherapy in cervical cancer

Cervical cancer is one of the most prevalent gynecologic malignancies, posing a significant threat to women's health and survival. Despite advancements in early screening and diagnosis, which have led to cervical cancer being termed a "preventable" cancer, treatment options for advanced and recurrent cervical cancer remain limited. Consequently, identifying new therapeutic targets and treatments is crucial for advancing the research and management of cervical cancer. In recent years, targeted therapy and immunotherapy have become focal points in oncology research, offering new avenues and directions for the treatment of cancer. Preclinical studies have demonstrated that targeting BMI1 can inhibit cervical cancer progression, while immunotherapy has advanced to phase III clinical trials, showing promising results. To date, there have been no reports on the combination of BMI1-targeted therapy and immunotherapy in cervical cancer. This review, therefore, elucidates the current state of research and explores the potential and perspectives of combining targeted therapy with immunotherapy for cervical cancer.

Mild near-infrared laser-triggered photo-immunotherapy potentiates immune checkpoint blockade via an all-in-one theranostic nanoplatform

One of the primary challenges for immune checkpoint blockade (ICB)-based therapy is the limited infiltration of T lymphocytes (T cells) into tumors, often referred to as immunologically "cold" tumors. A promising strategy to enhance the anti-tumor efficacy of ICB is to increase antigen exposure, thereby enhancing T cell activation and converting "cold" tumors into "hot" ones. Herein, we present an innovative all-in-one therapeutic nanoplatform to realize local mild photothermal- and photodynamic-triggered antigen exposure, thereby improving the anti-tumor efficacy of ICB. This nanoplatform involves conjugating programmed death-ligand 1 antibody (aPD-L1) with gadolinium-doped near-infrared (NIR)-emitting carbon dots (aPD-L1@GdCDs), which displays negligible cytotoxicity in the absence of light. But under controlled NIR laser irradiation, the GdCDs produce combined photothermal and photodynamic effects. This not only results in tumor ablation but also induces immunogenic cell death (ICD), facilitating enhanced infiltration of CD8+ T cells in the tumor area. Importantly, the combination of aPD-L1 with photothermal and photodynamic therapies via aPD-L1@GdCDs significantly boosts CD8+ T cell infiltration, reduces tumor size, and improves anti-metastasis effects compared to either GdCDs-based phototherapy or aPD-L1 alone. In addition, the whole treatment process can be monitored by multi-modal fluorescence/photoacoustic/magnetic resonance imaging (FLI/PAI/MRI). Our study highlights a promising nanoplatform for cancer diagnosis and therapy, as well as paves the way to promote the efficacy of ICB therapy through mild photothermal- and photodynamic-triggered immunotherapy.

Lipid nanoparticles deliver DNA-encoded biologics and induce potent protective immunity

Lipid nanoparticles (LNPs) for mRNA delivery have advanced significantly, but LNP-mediated DNA delivery still faces clinical challenges. This study compared various LNP formulations for delivering DNA-encoded biologics, assessing their expression efficacy and the protective immunity generated by LNP-encapsulated DNA in different models. The LNP formulation used in Moderna's Spikevax mRNA vaccine (LNP-M) demonstrated a stable nanoparticle structure, high expression efficiency, and low toxicity. Notably, a DNA vaccine encoding the spike protein, delivered via LNP-M, induced stronger antigen-specific antibody and T cell immune responses compared to electroporation. Single-cell RNA sequencing (scRNA-seq) analysis revealed that the LNP-M/pSpike vaccine enhanced CD80 activation signaling in CD8+ T cells, NK cells, macrophages, and DCs, while reducing the immunosuppressive signals. The enrichment of TCR and BCR by LNP-M/pSpike suggested an increase in immune response specificity and diversity. Additionally, LNP-M effectively delivered DNA-encoded antigens, such as mouse PD-L1 and p53R172H, or monoclonal antibodies targeting mouse PD1 and human p53R282W. This approach inhibited tumor growth or metastasis in several mouse models. The long-term anti-tumor effects of LNP-M-delivered anti-p53R282W antibody relied on memory CD8+ T cell responses and enhanced MHC-I signaling from APCs to CD8+ T cells. These results highlight LNP-M as a promising and effective platform for delivering DNA-based vaccines and cancer immunotherapies.

AXL: shapers of tumor progression and immunosuppressive microenvironments

As research progresses, our understanding of the tumor microenvironment (TME) has undergone profound changes. The TME evolves with the developmental stages of cancer and the implementation of therapeutic interventions, transitioning from an immune-promoting to an immunosuppressive microenvironment. Consequently, we focus intently on the significant role of the TME in tumor proliferation, metastasis, and the development of drug resistance. AXL is highly associated with tumor progression; however, previous studies on AXL have been limited to its impact on the biological behavior of cancer cells. An increasing body of research now demonstrates that AXL can influence the function and differentiation of immune cells, mediating immune suppression and thereby fostering tumor growth. A comprehensive analysis to identify and overcome the causes of immunosuppressive microenvironments represents a novel approach to conquering cancer. In this review, we focus on elucidating the role of AXL within the immunosuppressive microenvironments, discussing and analyzing the effects of AXL on tumor cells, T cells, macrophages, natural killer (NK) cells, fibroblasts, and other immune-stromal cells. We aim to clarify the contributions of AXL to the progression and drug resistance of cancer from its functional role in the immune microenvironment.

Lovastatin-mediated pharmacological inhibition of Formin protein DIAPH1 suppresses tumor immune escape and boosts immunotherapy response

BACKGROUND

The immunosuppressive tumor microenvironment (TME) is a key characteristic of human cancer. Immunotherapy has emerged as a promising treatment strategy to overcome immune escape and has gained widespread use in recent years. In particular, the blockade of PD-1/PD-L1 interaction holds significant importance in oncotherapy. Combining anti-PD-1/PD-L1 with small molecule inhibitors targeting key pathways represents an emerging trend in therapeutic development.

METHODS

To validate our findings biologically, we employed qRT-PCR or Western blotting and immunofluorescence staining techniques to assess the expression levels of DIAPH1 and PD-L1 in cells. Additionally, CCK8 and clone formation assays were utilized to evaluate cell proliferation ability, while flow assays were conducted to detect apoptosis in T cells.

RESULTS

Knockdown of DIAPH1 restored the tumor-killing capacity of T cells, effectively suppressing tumor immune escape. We observed a highly positive correlation between the expression levels of DIAPH1 and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), which can be competitively inhibited by lovastatin. Through Sybyl analysis followed by confirmation via micro scale thermophoresis, we identified lovastatin as a potential inhibitor targeting DIAPH1. Lovastatin downregulated DIAPH1 expression both in tumor cell lines and xenograft lung cancer tissues within a mouse lung cancer model. Furthermore, we found that lovastatin degraded DIAPH1 through lysosomal degradation pathway. Treatment with lovastatin was strongly associated with improved response rates and prolonged overall survival among patients with lung adenocarcinoma. Finally, overexpression of DIAPH1 reversed the inhibitory effects mediated by lovastatin on tumor development.

CONCLUSIONS

Lovastatin downregulates PD-L1 expression by targeting DIAPH1 and restores the tumor-killing ability of T cells to block tumor immune escape. Lovastatin may become a potential drug for cancer patients to enhance immunotherapy response in the clinic.

Relationship between CTF1 gene expression and prognosis and tumor immune microenvironment in glioma

OBJECTIVE

This study aimed to evaluate CTF1 expression in glioma, its relationship to patient prognosis and the tumor immune microenvironment, and effects on glioma phenotypes to identify a new therapeutic target for treating glioma precisely.

METHODS

We initially assessed the expression of CTF1, a member of the IL-6 family, in glioma, using bioinformatics tools and publicly available databases. Furthermore, we examined the correlation between CTF1 expression and tumor prognosis, DNA methylation patterns, m6A-related genes, potential biological functions, the immune microenvironment, and genes associated with immune checkpoints. We also explored potential associations with drug sensitivity. To assess the impact on glioma cell proliferation and apoptosis, we employed various assays, including the Cell Counting Kit-8, colony formation assay, and flow cytometry.

RESULTS

CTF1 gene and protein expression were significantly elevated in glioma tissues, and correlated with malignancy and poor prognosis. CTF1 was an independent prognostic factor and negatively associated with DNA methylation. The involvement of CTF1 in m6A modifications contributed to glioma progression. Enrichment analysis revealed immune response pathways linked with CTF1 in glioma, including natural killer cell cytotoxicity, NOD-like receptor signaling, Toll-like receptor signaling, antigen processing, chemokine signaling, and cytokine receptor interactions. CTF1 expression correlated positively with pathways related to apoptosis, inflammation, proliferation, and epithelial-mesenchymal transition, and PI3K-AKT-mTOR signaling. Additionally, CTF1 expression was positively associated with macrophage, eosinophil, and neutrophil contents and immune checkpoint-related genes, but negatively associated with sensitivity to 14 drugs. In vitro experiments confirmed that CTF1 knockdown inhibited glioma cell proliferation and promoted apoptosis.

CONCLUSION

This study identifies CTF1 as a significant independent prognostic factor that is closely associated with the tumor immune microenvironment in glioma. Additionally, reduced expression of CTF1 suppresses the proliferation and induces apoptosis of glioma cells in vitro. Consequently, CTF1 is a potentially promising novel therapeutic target for glioma treatment.

Targeted Delivery of BMS-1166 for Enhanced Breast Cancer Immunotherapy

Background

Cancer immunotherapy has achieved great success in breast cancer treatment in recent years. The Programmed Death-1 (PD-1) /Programmed Death-Ligand 1 (PD-L1) immune checkpoint pathway is among the most studied. BMS-1166, a PD-L1 inhibitor, can interfere with PD-1 and PD-L1 interaction. Transferrin Receptor 1 is a transmembrane glycoprotein overexpressed in various cancer cells, including breast cancer, and can specifically interact with the T7 (HAIYPRH) peptide.

Purpose

This study hypothesized that BMS-1166-loaded T7-modified poly(ethylene glycol)-poly(ε-caprolactone) (PEG-PCL) polymeric micelles (BMS-T7) could block PD-L1 interaction with PD-1, serving as a targeted immunotherapy for TfR1-positive breast cancer.

Methods

BMS-1166 was encapsulated in T7-PEG-PCL micelle. Particle size and zeta potential were determined by dynamic light scattering. Particle morphology was studied by transmission electron microscopy. The particles were characterized by Fourier transform infrared, thermogravimetric analysis, and differential scanning calorimetry. Drug encapsulation efficiency, loading degree, and release profile were examined by high-performance liquid chromatography. Human breast cancer MDA-MB-231 was used to test the cytotoxicity. Flow cytometry and immunofluorescence imaging were used to study the PD-L1 inhibition in cell surface and exosomes. MDA-MB-231 and Jurkat co-culture studied T-cell activation and apoptosis.

Results

The particle size of the empty and drug-loaded micelles showed a size distribution with an average diameter of 54.62 ± 2.28 nm and 60.22 ± 2.56 nm, respectively. The encapsulation efficiency of BMS-T7 was 83.89 ± 5.59%. The release half-life of drug-loaded micelles was 48h. The IC50 of BMS-1166 was 28.77 μM in MDA-MB-231 cells. In addition, the BMS-T7 showed a better inhibitory effect on PD-L1 expression in breast cancer cells and exosomes than the naked drug. The formulation significantly restored T-cell function compared to the BMS-1166 treatment.

Conclusion

These results provide preliminary evidence indicating that BMS-T7 may have the potential to deliver drugs to breast cancer cells via active targeting and hold great promise in cancer immunotherapy drug delivery applications.