Mutual exclusivity and co-occurrence patterns of immune checkpoints indicate NKG2A relates to anti-PD-1 resistance in gastric cancer

Tumor immune microenvironment remodeling after neoadjuvant therapy in gastric cancer: Update and new challenges

Gastric cancer (GC) is a malignant tumor with one of the highest morbidity and death rates in the world. Neoadjuvant therapy, including neoadjuvant chemotherapy (NAC) and NAC combined with immunotherapy, can improve the resection and long-term survival rates. However, not all patients respond well to neoadjuvant therapy. It has been confirmed that immune cells in the tumor immune microenvironment, including T cells, B cells, and natural killer cells, can affect the efficacy of neoadjuvant therapy. This paper summarizes current preclinical and clinical evidence to more fully describe the effects of neoadjuvant therapy on the immune microenvironment of GC, to provide the impetus to identify biomarkers to predict the potency of neoadjuvant therapy, and to identify the mechanisms of drug resistance, which should promote the development of individualized and accurate treatments for GC patients.

Regulation of the CD8⁺ T cell and PDL1/PD1 axis in gastric cancer: Unraveling the molecular landscape

Gastric cancer (GC) remains a significant global health burden, mainly due to immune evasion mechanisms within its complex tumor microenvironment (TME). The interaction between CD8⁺ T cells and the PD1/PDL1 axis is central to these mechanisms. CD8⁺ T cells, key players in antitumor immunity, often exhibit impaired functionality in the GC TME, primarily due to PD1-mediated inhibitory signaling induced by PDL1 expressed on tumor and immune cells. Recent findings have elucidated intricate molecular interactions governing PD1 expression on CD8⁺ T cells and the modulation of PDL1 on tumor cells and immune cells by diverse signals such as cytokines, metabolic factors, and noncoding RNAs. While high PD1 expression typically indicates CD8⁺ T cell exhaustion and poor clinical outcomes, recent studies highlight scenarios where elevated PD1 levels correlate with preserved or enhanced T cell cytotoxic activity, suggesting nuanced regulatory pathways. Therapeutic strategies that disrupt PD1/PDL1 interactions, through checkpoint inhibitors or pharmacological modulation, have demonstrated potential in reactivating antitumor responses. However, resistance mechanisms, including altered antigen presentation, metabolic reprogramming, and immunosuppressive cell infiltration, continue to limit efficacy. Emerging combination therapies, biomarker-driven patient stratification, and novel targets like noncoding RNAs and exosomal PDL1 represent promising avenues to enhance treatment effectiveness. This review synthesizes current insights into the molecular regulation of CD8⁺ T cell functionality and the PD1/PDL1 axis, highlighting potential therapeutic strategies to restore antitumor immunity and improve patient outcomes in gastric cancer.

Integrative analysis of single-cell and bulk RNA sequencing reveals the oncogenic role of ANXA5 in gastric cancer and its association with drug resistance

Background

Gastric cancer (GC) remains a leading cause of cancer-related mortality, with over one million new cases and 769,000 deaths reported in 2020. Despite advancements in chemotherapy, surgery, and targeted therapies, delayed diagnosis due to overlooked early symptoms leads to poor prognosis.

Methods

We integrated bulk RNA sequencing and single-cell RNA sequencing datasets from TCGA, GEO, and OMIX001073, employing normalization, batch effect correction, and dimensionality reduction methods to identify key cell populations associated with GC invasion and epithelial-mesenchymal transition (EMT), as well as analyze the tumor immune microenvironment.

Results

Our analysis identified the MUC5AC+ malignant epithelial cell cluster as a significant player in GC invasion and EMT. Cluster 1, representing this cell population, exhibited higher invasion and EMT scores compared to other clusters. Survival analysis showed that high abundance in cluster 0 correlated with improved survival rates (P=0.012), whereas cluster 1 was associated with poorer outcomes (P=0.045). A prognostic model highlighted ANXA5 and GABARAPL2 as two critical genes upregulated in GC tumors. High-risk patients demonstrated increased immune cell infiltration and worse prognosic. Analysis of tumor mutation burden (TMB) indicated that patients with low TMB in the high-risk group had the worst prognosis. Wet-lab validation experiments confirmed the oncogenic role of ANXA5, showing its facilitation of cell proliferation, invasion, and migration while suppressing apoptosis.

Conclusion

This study offers novel insights into the subpopulations of malignant epithelial cells in GC and their roles in tumor progression. It provides a prognostic model and potential therapeutic targets to combat GC, contributing crucial understanding to the fundamental mechanisms of drug resistance in gastrointestinal cancers.

Overcoming immunotherapy resistance in gastric cancer: insights into mechanisms and emerging strategies

Gastric cancer (GC) remains a leading cause of cancer-related mortality worldwide, with limited treatment options in advanced stages. Immunotherapy, particularly immune checkpoint inhibitors (ICIs) targeting PD1/PD-L1, has emerged as a promising therapeutic approach. However, a significant proportion of patients exhibit primary or acquired resistance, limiting the overall efficacy of immunotherapy. This review provides a comprehensive analysis of the mechanisms underlying immunotherapy resistance in GC, including the role of the tumor immune microenvironment, dynamic PD-L1 expression, compensatory activation of other immune checkpoints, and tumor genomic instability. Furthermore, the review explores GC-specific factors such as molecular subtypes, unique immune evasion mechanisms, and the impact of Helicobacter pylori infection. We also discuss emerging strategies to overcome resistance, including combination therapies, novel immunotherapeutic approaches, and personalized treatment strategies based on tumor genomics and the immune microenvironment. By highlighting these key areas, this review aims to inform future research directions and clinical practice, ultimately improving outcomes for GC patients undergoing immunotherapy.

SMR-guided molecular subtyping and machine learning model reveals novel prognostic biomarkers and therapeutic targets in non-small cell lung adenocarcinoma

Non-small cell lung adenocarcinoma (LUAD) is a markedly heterogeneous disease, with its underlying molecular mechanisms and prognosis prediction presenting ongoing challenges. In this study, we integrated data from multiple public datasets, including TCGA, GSE31210, and GSE13213, encompassing a total of 867 tumor samples. By employing Mendelian randomization (MR) analysis, machine learning techniques, and comprehensive bioinformatics approaches, we conducted an in-depth investigation into the molecular characteristics, prognostic markers, and potential therapeutic targets of LUAD. Our analysis identified 321 genes significantly associated with LUAD, with CENP-A, MCM7, and DLGAP5 emerging as highly connected nodes in network analyses. By performing correlation analysis and Cox regression analysis, we identified 26 prognostic genes and classified LUAD samples into two molecular subtypes with significantly distinct survival outcomes. The Random Survival Forest (RSF) model exhibited robust prognostic predictive capabilities across multiple independent cohorts (AUC > 0.75). Beyond merely predicting patient outcomes, this model also captures key features of the tumor immune microenvironment and potential therapeutic responses. Functional enrichment analysis revealed the complex interplay of cell cycle regulation, DNA repair, immune response, and metabolic reprogramming in the progression of LUAD. Furthermore, we observed a strong correlation between risk scores and the expression of specific cytokines, such as CCL17, CCR2, and CCL20, suggesting novel avenues for developing cytokine network-based therapeutic strategies. This study offers fresh insights into the molecular subtyping, prognostic prediction, and personalized therapeutic decision-making in LUAD, laying a critical foundation for future clinical applications and targeted therapy research.

A New Medical Evaluation for Gastric Cancer Patients to Increase the Success Rate of Immunotherapy: A 2024 Update

Researchers have performed numerous studies on immunotherapy because of the high death rate associated with gastric cancer (GC). GC immunotherapy research has made tremendous progress, and we wanted to provide an update on this topic. On the basis of this update, we suggest performing a new medical evaluation before initiating immunotherapy in patients with GC to increase the success rate of immunotherapies. We propose that before patients start GC immunotherapy, they should be evaluated and given a score of one to two points for the following factors: immunopathological features, molecular and genomic features, potential consequences for bacterial pathogens, potential immunotherapeutic resistance and hyperprogressive illness, and the potential to use biomarkers to gauge their prognosis and immunotherapy responses to optimize immunotherapy following surgery. The proposed scoring system could also help in the diagnosis of GC. With all the advances in genetics, immunology, and microbiology, the diagnosis of GC could be improved, not changed. Currently, patients diagnosed with GC undergo surgical resection as the only permanent solution. Patients who meet the maximum score from the presented proposal could be eligible immediately after diagnosis for immunotherapy. Therefore, immunotherapy could be a first-line option for clinicians.