Clinical outcome and molecular landscape of patients with ARID1A-loss gastric cancer.

Chromatin remodelers are commonly altered in human cancer. The mutation of AT-rich interactive domain 1A (ARID1A) in gastric cancer (GC), a component of the SWI/SNF chromatin remodeling complex, was proven associated with treatment response in our previous study. However, ARID1A loss of function was caused not only by mutations but also copy number deletions. The clinicopathologic, genomic, and immunophenotypic correlates of ARID1A loss is largely uncharacterized in GC. Here, 819 patients with clinicopathological information and sequencing data or formalin-fixed paraffin-embedded tissues from four cohorts, Zhongshan Hospital (ZSHS) cohort (n = 375), The Cancer Genome Atlas (TCGA) cohort (n = 371), Samsung Medical Center (SMC) cohort (n = 53), and ZSHS immunotherapy cohort (n = 20), were enrolled. ARID1A loss was defined by genome sequencing or deficient ARID1A expression by immunohistochemistry. We found that ARID1A mutation and copy number deletion were enriched in GC with microsatellite instability (MSI) and chromosomal-instability (CIN), respectively. In the TCGA and ZSHS cohorts, only CIN GC with ARID1A loss could benefit from fluorouracil-based adjuvant chemotherapy. In the SMC and ZSHS immunotherapy cohorts, ARID1A loss exhibited a tendency of superior responsiveness and indicated favorable overall survival after anti-PD-1 immunotherapy. ARID1A-loss tumors demonstrated elevated mutation burden, neoantigen load, and interferon gamma pathway activation. Moreover, in CIN GC, ARID1A loss was correlated with higher homologous recombination deficiency. ARID1A loss defines a distinct subtype of GC characterized by high levels of genome instability, neoantigen formation, and immune activation. These tumors show sensitivity to both chemotherapy and anti-PD-1 immunotherapy. This study provides valuable insights for precision treatment strategies in GC.

Complement receptor C5aR1 blockade reprograms tumor-associated macrophages and synergizes with anti-PD-1 therapy in gastric cancer.

In gastric cancer (GC), the therapeutic response of immune checkpoint blockade (ICB) remains suboptimal. Targeting myeloid cell checkpoints might be feasible as adjuvant to current ICB regimens. We sought to evaluate the crucial role of C5aR1+ TAMs in regulating antitumor immunity and the efficacy of combinatorial treatment with antiprogrammed cell death protein-1 (PD-1) and C5aR1 blockade. Here, we found that C5aR1 was predominantly expressed on macrophages and high level of C5aR1+ TAMs infiltration could predict poor prognosis and inferior chemotherapeutic response. The flow cytometry (FCM) and single-cell RNA-seq (scRNA-seq) data revealed that C5aR1+ TAMs exhibited immunosuppressive property which might contribute to CD8+ T cell dysfunction. Blockade of C5aR1 could diminish the immunosuppressive function of TAMs and led to reinvigorated CD8+ T cells mediated antitumor immunity. Moreover, using in vitro intervention experiment based on fresh GC surgical specimens, we discovered that C5aR1 blockade exert a synergistic effect when combined with PD-1 inhibitor for tumor clearance. Our study demonstrated that C5aR1 is a critical myeloid checkpoint and plays a crucial role in regulating the immunosuppressive property of TAMs and CD8+ T cell immune tolerance. C5aR1 blockade reprograms TAMs and reinvigorated the cytotoxicity of CD8+ T cells, thus improving the efficacy of anti-PD-1 therapy for tumor eradication in GC.

C-type lectin receptor Dectin-1 blockade on tumour-associated macrophages improves anti-PD-1 efficacy in gastric cancer.

BACKGROUND: This study aimed to investigate the expression and clinical significance of Dendritic cell-associated C-type lectin-1 (Dectin-1) in gastric cancer (GC), and to explore the mechanism of Dectin-1 regulating tumour-associated macrophage (TAM)-mediated immune evasion in GC. METHODS: The association of Dectin-1+ cells with clinical outcomes was inspected by immunohistochemistry on tumour microarrays. Flow cytometry and RNA sequencing were applied to detect characteristics of T cells, phenotypic and transcriptional features of Dectin-1+ TAMs. The effect of Dectin-1 blockade was evaluated using an in vitro intervention experiment based on fresh GC tissues. RESULTS: High infiltration of intratumoral Dectin-1+ cells predicted poor prognosis in GC patients. Dectin-1+ cells were mainly composed of TAMs, and the accumulation of Dectin-1+ TAMs was associated with T-cell dysfunction. Notably, Dectin-1+ TAMs exhibited an immunosuppressive phenotype. Furthermore, blockade of Dectin-1 could reprogramme Dectin-1+ TAMs and reactivate anti-tumour effects of T cells, as well as enhanced PD-1 inhibitor-mediated cytotoxicity of CD8+ T cells against tumour cells. CONCLUSIONS: Dectin-1 could affect T-cell anti-tumour immune response by regulating the immunosuppressive function of TAMs, leading to poor prognosis and immune evasion in GC patients. Blockade of Dectin-1 can be used alone or in combination with current therapeutic strategies in GC.

Somatic ARID1A mutation stratifies patients with gastric cancer to PD-1 blockade and adjuvant chemotherapy.

BACKGROUND: AT-rich interaction domain 1A (ARID1A) encodes a vital component of switch/sucrose non-fermentable chromatin-remodeling complex. Given its association with genomic instability, we conducted this study to determine whether ARID1A mutation status had an impact on therapeutic responsiveness in gastric cancer (GC), especially combinatory chemo-immunotherapy. METHODS: We retrospectively enrolled a total of 1162 patients from five independent cohorts. ZSHS Cohort and TCGA Cohort were designed to inform chemotherapeutic relevance and immunobiology of ARID1A-mutant GC based on tissue samples and sequencing data, respectively. MSKCC Cohort, mGC Cohort, and Melanoma Cohort were utilized to interrogate the predictive efficacy of ARID1A mutation to programmed cell death protein 1 (PD-1) blockade. RESULTS: ARID1A mutation was enriched in EBV-positive, hypermutated-single nucleotide variant and microsatellite-unstable subtype GC, and was predictive of responsiveness to both fluorouracil-based chemotherapy and PD-1 blockade. Specifically, ARID1A mutation score was a highly sensitive indicator (91%) of response to pembrolizumab. Mechanistically, ARID1A mutation correlated with extensive DNA damage repair deficiency and immunogenic tumor microenvironment (TME) featured by elevated activated subsets of CD8+ T cells, CD4+ T cells, and NK cells. Type 17T helper cells were typically abundant in ARID1A-mutant GC and might be a precondition for chemosensitivity conferred by ARID1A mutation. Furthermore, ARID1A mutation indicated elevated expression of VEGFA and CLDN18, as well as over-representation of ERBB2 and FGFR2 signaling pathway. CONCLUSIONS: ARID1A-mutant GC displayed immunogenic TME and might be a candidate for both monotherapy and the combination of frontline chemotherapy and PD-1 blockade.

Impact of intratumoural CD96 expression on clinical outcome and therapeutic benefit in gastric cancer.

CD96 was identified as a novel immune checkpoint. However, the role of CD96 in the gastric cancer (GC) microenvironment remains fragmentary. This study aimed to probe the clinical significance of CD96 to predict prognosis and therapeutic responsiveness, and to reveal the immune contexture and genomic features correlated to CD96 in GC patients. We enrolled 496 tumor microarray specimens of GC patients from Zhongshan Hospital (ZSHS) for immunohistochemical analyses. Four hundred and twelve GC patients from the Cancer Genome Atlas (TCGA) and 61 GC patients treated with pembrolizumab from ERP107734 published in the European Nucleotide Archive (ENA) were gathered for further analysis of the association between CD96+ cell infiltration and immune contexture, molecular characteristics, and genomic features by CIBERSORT and gene set enrichment analysis. Clinical outcomes were analyzed by Kaplan-Meier curves, the Cox model, interaction testing, and receiver operating characteristic analysis. High CD96+ cell infiltration predicted poor prognosis and inferior survival benefits from fluorouracil-based adjuvant chemotherapy in the ZSHS cohort whereas superior therapeutic responsiveness to pembrolizumab was shown in the ENA cohort. CD96-enriched tumors showed an immunosuppressive tumor microenvironment featured by exhausted CD8+ T-cell infiltration in both the ZSHS and TCGA cohorts. Moreover, in silico analysis for the TCGA cohort revealed that several biomarker-targeted pathways displayed significantly elevated enrichment levels in the CD96 high subgroup. This study elucidated that CD96 might drive an immunosuppressive contexture with CD8+ T-cell exhaustion and represent an independent adverse prognosticator in GC. CD96 could potentially be a novel biomarker for precision medicine of adjuvant chemotherapy, immunotherapy, and targeted therapies in GC.

TIM3+ cells in gastric cancer: clinical correlates and association with immune context.

BACKGROUND: T cell immunoglobulin and mucin domain-containing protein 3 (TIM3) is a crucial immune checkpoint and is considered as an emerging target for cancer treatment. However, the clinical significance and immune-related role of TIM3+ cells in gastric cancer remain unknown. This study aimed to investigate the clinical significance of tumour-infiltrating TIM3+ cells and their association with immune contexture in gastric cancer. METHODS: This study enrolled three cohorts, including 436 tumour tissue microarray specimens and 58 fresh tumour tissues of gastric cancer patients from Zhongshan Hospital, and 330 transcriptional data from The Cancer Genome Atlas. TIM3+ cells and their association with CD8+ T cells were evaluated by immunohistochemistry and flow cytometry analyses. Kaplan-Meier curves, Cox model and interaction test were performed to assess clinical outcomes. RESULTS: Tumour-infiltrating TIM3+ cells' high subgroups experienced poorer overall survival and disease-free survival and predicted inferior therapeutic responsiveness to fluorouracil-based adjuvant chemotherapy. TIM3 indicated CD8+ T cell dysfunction, which impeded chemotherapeutic responsiveness. Besides, HAVCR2 messenger RNA expression was associated with specific molecular characteristics. CONCLUSIONS: The abundance of tumour-infiltrating TIM3+ cells could identify an immunoevasive subtype gastric cancer with CD8+ T cell dysfunction, suggesting that TIM3 might serve as a promising target for immunotherapy in gastric cancer.

Intratumoral PD-1+CD8+ T cells associate poor clinical outcomes and adjuvant chemotherapeutic benefit in gastric cancer.

BACKGROUND: Although PD-1 has been reported to be a marker of T-cell exhaustion in several malignancies, the biological role of PD-1+CD8+ T cells in gastric cancer (GC) remains unclear. Herein, we aimed to investigate the role of PD-1+CD8+ T cells in the tumour microenvironment and its clinical significance in GC. DESIGNS: This study included 441 tumour microarray specimens and 60 Flow cytometry specimens of GC patients from Zhongshan Hospital, and 250 GC patients from the Asian Cancer Research Group. RESULTS: Here, we demonstrated that PD-1+CD8+ T cells functioned as an independent adverse prognosticator in GC. In addition, an abundance of intratumoral PD-1+CD8+ T cells indicated worse chemotherapeutic responsiveness to fluorouracil in Stage III GC patients. Mechanistically, PD-1+CD8+ T cell high infiltration indicated an exhausted phenotype of global CD8+ T cells in GC tissues, which was characterised by elevated immune checkpoint expression including CTLA-4 and TIM-3, whereas decreased expression of perforin. Furthermore, PD-1+CD8+ T cell high-infiltration patients with Stage III GC held elevated activity of several therapeutic signal pathways. CONCLUSIONS: Our study highlighted that PD-1+CD8+ T cell abundance predicts inferior prognosis in GC, and may serve as a novel predictive biomarker to guide therapeutic option.

Latency-associated Peptide Identifies Immunoevasive Subtype Gastric Cancer With Poor Prognosis and Inferior Chemotherapeutic Responsiveness.

OBJECTIVE: To examine the clinical significance of LAP to predict survival outcomes and chemotherapeutic responsiveness in gastric cancer. BACKGROUND: LAP has been shown to possess significant immunoregulatory roles in several malignancies. However, the role and clinical significance of LAP in gastric cancer still remains unknown. METHODS: Four hundred and fifty-six tumor tissue microarray specimens, 80 fresh tumor tissue samples of gastric cancer patients from Zhongshan Hospital, Fudan University and transcriptomic and clinical data of 328 gastric cancer patients from the Cancer Genome Atlas were analyzed. LAP expression and immune contexture were examined by immunohistochemistry, CIBERSORT, and flow cytometry. Clinical outcomes of patient subgroups were compared by Kaplan-Meier curves, Cox model and interaction test. RESULTS: High LAP expression predicted poor overall survival (P < 0.001, P < 0.001, and P = 0.022) and inferior therapeutic responsiveness to fluorouracil-based adjuvant chemotherapy (P = 0.008 for interaction) in gastric cancer. LAP was associated with immunoevasive tumor microenvironment featured by dysfunctional CD8+ T cells infiltration (P < 0.001). The LAP-associated dysfunctional CD8+ T cells had an exhausted phenotype with decreased effector molecules such as interferon-γ, granzyme B, and perforin, but also elevated programmed cell death protein-1, which resulted in poor prognosis and inferior therapeutic responsiveness. CONCLUSIONS: This study revealed that LAP could identify immunoevasive subtype gastric cancer, indicating LAP might be a potential immunotherapeutic target and facilitate patient counseling on individualized adjuvant therapy and follow-up scheduling in gastric cancer.

Poor Clinical Outcomes and Immunoevasive Contexture in Intratumoral IL-10-Producing Macrophages Enriched Gastric Cancer Patients.

OBJECTIVE: To investigate the clinical significance of IL-10+ tumor-associated macrophages (TAMs) in gastric cancer. BACKGROUND: Due to the plasticity and diversity of TAMs, it is necessary to phenotypically and functionally classify subsets of TAMs to better understand the critical role of TAMs in cancer progression. TAMs expressing interleukin-10 (IL-10) have been found to facilitate immune evasion in many malignancies, but the role of IL-10+ TAMs in gastric cancer remains obscure. METHODS: Four hundred and sixty-eight tumor tissue microarray specimens, 52 fresh tumor tissue samples of gastric cancer patients from Zhongshan Hospital, and data of 298 gastric cancer patients from the Cancer Genome Atlas (TCGA) were analyzed. IL-10+ TAM level and immune contexture were examined by CIBERSORT, immunohistochemistry, and flow cytometry. Clinical outcomes were analyzed by Kaplan-Meier curves and Cox model. RESULTS: Gastric cancer patients with high IL-10+ TAM infiltration exhibited poor prognosis and inferior therapeutic responsiveness to fluorouracil-based adjuvant chemotherapy. IL-10+ TAM infiltration yielded an immunoevasive tumor microenvironment featured by regulatory T cell infiltration and CD8+ T cell dysfunction. The combinational analysis of IL-10+ TAM and CD8+ T cell infiltration stratified patients into distinct risk groups with different clinical outcomes. Moreover, IL-10+ TAM infiltration was correlated with tumor-intrinsic characteristics including EBV status, PD-L1 expression, and genome stability in gastric cancer. CONCLUSIONS: This study revealed that IL-10+ TAMs might drive an immunoevasive microenvironment and determine poor prognosis and inferior therapeutic responsiveness to fluorouracil-based adjuvant chemotherapy, indicating IL-10+ TAMs could be applied as a potential target for immunotherapeutic approach in gastric cancer.

Intratumoral Foxp3+RORγt+ T cell infiltration determines poor prognosis and immunoevasive contexture in gastric cancer patients.

BACKGROUND: Foxp3+RORγt+ T cells possess both characteristics of regulatory T cells and T helper 17 cells and show significant immunoregulatory functions in autoimmune diseases. However, the role and clinical significance of Foxp3+RORγt+ T cells in gastric cancer remains unclear. METHODS: We enrolled 452 gastric cancer tissue microarray samples and 60 fresh tumor tissue samples from Zhongshan Hospital. The infiltration of Foxp3+RORγt+ T cells and immune contexture were examined by immunohistochemistry and flow cytometry. Survival analyses of patient subgroups were conducted by Kaplan-Meier curves, log-rank test and Cox proportional model. RESULTS: High infiltration of Foxp3+RORγt+ T cells predicted poor overall survival (P = 0.0222 and 0.0110) and inferior therapeutic response (P = 0.003 for interaction) in gastric cancer. Foxp3+RORγt+ T cells were associated with impaired effective function of CD8+ T cells featured by decreased interferon-γ, granzyme B and CD107a expression. Co-evaluation of Foxp3+RORγt+ T cells and CD8+ T cells could predict survival outcomes and chemotherapeutic responsiveness more precisely. CONCLUSIONS: We found that Foxp3+RORγt+ T cells could potentially attenuate effective functions of CD8+ T cells and led to adverse survival outcomes and inferior chemotherapeutic responsiveness. Moreover, the novel co-evaluation system might be useful for prognosis prediction for appropriate treatment in gastric cancer. NOVELTY AND IMPACT STATEMENTS: Clinical significance of Foxp3+RORγts+ T cells has not been studied in gastric cancer. Herein, we investigated the prognostic value of Foxp3+RORγt+ T cells in 452 patients. We demonstrated that intratumoral Foxp3+RORγt+ T cell infiltration was a prognostic biomarker for overall survival and the identification of patients might benefit from post-gastrectomy 5-fluorouracil. These findings allow a more precise stratification upon the co-evaluation with CD8+ T cells to better clinical management for patients who would benefit from 5-fluorouracil.

Clinical Outcomes and Immune Metrics in Intratumoral Basophil-Enriched Gastric Cancer Patients.

BACKGROUND: Accumulation of basophils has been reported in several malignancies. In gastric cancer, the relation between tumor-infiltrating basophils and patient overall survival and chemotherapeutic responsiveness still remains obscure. OBJECTIVE: We aimed to investigate the postoperative prognostic and predictive significance of basophils to survival outcomes and chemotherapeutic responsiveness in resectable gastric cancer. METHODS: The study enrolled two independent patient data sets with 448 gastric cancer patients overall. Basophils were evaluated with the use of immunohistochemistry (IHC) staining, and the correlation with clinicopathological characteristics, survival outcomes, and responsiveness to fluorouracil-based adjuvant chemotherapy (ACT) were investigated. Additionally, IHC was applied to characterize immune contexture in gastric cancer. RESULTS: In either the discovery or validation data sets, accumulated basophils indicated poorer prognosis, and tumor-infiltrating basophils were identified as an independent adverse prognostic factor by multivariate analysis. Furthermore, tumor-infiltrating basophils determined significantly inferior therapeutic responsiveness to fluorouracil-based ACT in patients with stage III tumors. In addition, the abundance of basophils was correlated with an immunoevasive contexture characterized by M2-polarized macrophage infiltration. Moreover, our findings indicated elevated interleukin-4 expression but decreased interferon-γ expression in the high-basophils subgroup. CONCLUSIONS: Tumor-infiltrating basophils in gastric cancer were identified as an independent adverse prognosticator, and also predicted inferior chemotherapeutic responsiveness, which identified those patients in need of much more individualized postoperative adjuvant therapy and more stringent follow-up. Furthermore, the infiltration of basophils was associated with immunoevasive tumor microenvironment, which might be a potential immunotherapeutic target for gastric cancer.

Identification and validation of an immunogenic subtype of gastric cancer with abundant intratumoural CD103+CD8+ T cells conferring favourable prognosis.

BACKGROUND: Intratumoural CD103+CD8+ T cells have been linked to prolonged survival in several malignancies. However, the clinical significance of CD103+CD8+ T cells in gastric cancer remains unexplored. METHODS: Gastric cancer tissues from Zhongshan Hospital and data from Gene Expression Omnibus were obtained and analysed. Immunohistochemistry and flow cytometry were performed to detect the number and phenotypical characteristics of CD103+CD8+ T cells. The effect of programmed cell death protein-1 (PD-1) blockade on CD103+CD8+ T cells was evaluated with the use of an in vitro study based on fresh tumour tissues. RESULTS: CD103+CD8+ T cells predicted superior overall survival and provided better prognostic power than total CD8+ T cells in gastric cancer. Patients with high CD103+CD8+ T cell infiltration also gained more benefit from adjuvant chemotherapy. Flow cytometry analysis showed that CD103+CD8+ T cells exerted superior anti-tumour effects with stronger retention capacity and cytotoxicity. Moreover, an in vitro study showed that CD103+CD8+ T cells were more functionally restored after PD-1 blockade than CD103-CD8+ T cells. CONCLUSIONS: CD103+CD8+ T cells might be a useful marker to predict prognosis and therapeutic efficacy for gastric cancer patients. Efforts to increase intratumoural CD103+CD8+ T cell frequency might be a novel therapeutic strategy in gastric cancer.

Lauren classification identifies distinct prognostic value and functional status of intratumoral CD8+ T cells in gastric cancer.

With dichotomous etiology and pathogenesis, intestinal type and diffuse type gastric cancers vary in their clinical and molecular features to the point of representing distinct entities. However, the differences of tumor-infiltrating immune cells within the two types of gastric cancer have not been well researched. This study was aimed to evaluate the functional impact of Lauren classification on immune contexture in gastric cancer patients. Tumor tissues of gastric cancer patients from Zhongshan Hospital and gastric cancer data from The Cancer Genome Atlas (TCGA) cohort were analyzed. By immunohistochemistry and flow cytometry, we found that intratumoral CD8+ T cells were more abundant but less functional in diffuse type as compared with those in intestinal type tumor tissues. Survival analysis indicated that CD8+ T cells yielded favorable prognosis only in intestinal type patients other than diffuse type cancer patients. Moreover, such diffuse type-associated CD8+ T cell dysfunction was featured by elevated expression of immunosuppressive factors including interleukin-10 (IL-10), transforming growth factor-ß1 (TGF-ß1) and indoleamine 2,3-dioxygenase 1 (IDO1). In summary, we found that the density, prognostic significance and functional status of intratumoral CD8+ T cells varied with Lauren subtypes in gastric cancer. These results further indicated Lauren classification might be a potential therapeutic marker, and should be considered in therapeutic decisions, especially immunotherapeutic eligibility.

CXCL13 expression is prognostic and predictive for postoperative adjuvant chemotherapy benefit in patients with gastric cancer.

BACKGROUND: Chemokine (C-X-C motif) ligand 13 (CXCL13/BLC/BCA-1) is a cytokine from C-X-C chemokine family, which is selectively chemotactic for B cells. Previous research has demonstrated that high CXCL13 expression is correlated to poor prognosis in various cancers. However, the association between CXCL13 expression and gastric cancer is still unclear. METHODS: Intratumoral CXCL13 expression was evaluated by immunohistochemistry using a semi-quantitative method (modified H-score) in a testing set of 214 and a validation set of 227 randomly selected gastric cancer patients resected in 2008 in one institution. The median value was used as the cut-off point. We performed correlative analysis of CXCL-13 expression with clinicopathological variables, Kaplan-Meier analysis for association with overall survival (OS), and multivariate modeling. RESULTS: High CXCL13 expression was associated with larger tumor diameter and shorter OS. By multivariate analysis, CXCL13 expression was associated with OS independently from clinicopathological factors. Within the T2-4 stage patients group, low CXCL13 expression was associated with longer survival, especially in the subgroup of patients (57.6%) who received adjuvant chemotherapy. CONCLUSIONS: Intratumoral CXCL13 expression appears as an independent prognostic marker for patients after gastric cancer resection. In addition, CXCL13 expression may serve as a predictive biomarker of response to postoperative adjuvant chemotherapy in these patients.

Targeting myeloid checkpoint Siglec-10 reactivates antitumor immunity and improves anti-programmed cell death 1 efficacy in gastric cancer.

OBJECTIVE: Immunotherapy has not yielded satisfactory therapeutic responses in gastric cancer (GC). However, targeting myeloid checkpoints holds promise for expanding the potential of immunotherapy. This study aims to evaluate the critical role of Siglec-10+ tumor-associated macrophages (TAMs) in regulating antitumor immunity and to explore the potential of the myeloid checkpoint Siglec-10 as an interventional target. DESIGN: Siglec-10+ TAMs were assessed based on immunohistochemistry on tumor microarrays and RNA-sequencing data. Flow cytometry, RNA sequencing, and single-cell RNA-sequencing analysis were employed to characterize the phenotypic and transcriptional features of Siglec-10+ TAMs and their impact on CD8+ T cell-mediated antitumor immunity. The effectiveness of Siglec-10 blockade, either alone or in combination with anti-programmed cell death 1 (PD-1), was evaluated using an ex vivo GC tumor fragment platform based on fresh tumor tissues. RESULTS: Siglec-10 was predominantly expressed on TAMs in GC, and associated with tumor progression. In Zhongshan Hospital cohort, Siglec-10+ TAMs predicted unfavorable prognosis (n=446, p<0.001) and resistance to adjuvant chemotherapy (n=331, p<0.001), which were further validated in exogenous cohorts. In the Samsung Medical Center cohort, Siglec-10+ TAMs demonstrated inferior response to pembrolizumab in GC (n=45, p=0.008). Furthermore, Siglec-10+ TAMs exhibited an immunosuppressive phenotype and hindered T cell-mediated antitumor immune response. Finally, blocking Siglec-10 reinvigorated the antitumor immune response and synergistically enhances anti-PD-1 immunotherapy in an ex vivo GC tumor fragment platform. CONCLUSIONS: In GC, the myeloid checkpoint Siglec-10 contributes to the regulation of immunosuppressive property of TAMs and promotes the depletion of CD8+ T cells, ultimately facilitating immune evasion. Targeting Siglec-10 represents a potential strategy for immunotherapy in GC.

Intratumoral IL-1R1 expression delineates a distinctive molecular subset with therapeutic resistance in patients with gastric cancer.

BACKGROUND: With the essential role of interleukin-1 signaling in cancer-related inflammation, IL-1R1, the main receptor for both IL-1α and IL-1ß, demonstrated therapeutic potential in several types of cancer, which has been put into clinical trials. However, the expression profile and critical role of IL-1R1 in gastric cancer (GC) remain obscure. This study aimed to investigate the prognostic significance of IL-1R1 expression and its predictive value for chemotherapy and immunotherapy in GC. METHODS: The study enrolled three cohorts, consisting of 409 tumor microarray specimens of GC patients from Zhongshan Hospital, 341 transcriptional data from The Cancer Genome Atlas, and 45 transcriptional data from patients treated with pembrolizumab. IL-1R1 mRNA expression was directly acquired from public datasets, and we also detected IL-1R1 protein expression on tumor microarray by immunohistochemistry. Finally, the associations of IL-1R1 expression with clinical outcomes, immune contexture, and genomic features were analyzed. RESULTS: High IL-1R1 expression predicted poor prognosis and inferior responsiveness to both 5-fluorouracil-based adjuvant chemotherapy (ACT) and immune checkpoint blockade (ICB). IL-1R1 fostered an immunosuppressive microenvironment characterized by upregulated M2 macrophages and exhausted CD8+ T cells infiltration. Moreover, the expression of IL-1R1 was intrinsically linked to genomic alterations associated with targeted therapies in GC. CONCLUSIONS: IL-1R1 served as an independent prognosticator and predictive biomarker for ACT and ICB in GC. Furthermore, IL-1R1 antagonists could be a novel agent alone or combined with current therapeutic strategies in GC.

Intratumoral CXCR5+CD8+T associates with favorable clinical outcomes and immunogenic contexture in gastric cancer.

Studies that examined an association between CD8+T and prognosis in gastric cancer are inconsistent, and a distinct population of CXCR5+CD8+T associated with better overall survival has been reported among various malignancies. Here, we show that the abundance of intratumoral CXCR5+CD8+T cells is associated with better overall survival in patients with gastric cancer. Patients with TNM II + III gastric cancer with higher intratumoral CXCR5+CD8+T cell infiltration are more likely to benefit from adjuvant chemotherapy. Microsatellite-unstable and Epstein-Barr virus positive tumors are enriched with CXCR5+CD8+T cells. Gastric cancer infiltrating CXCR5+CD8+T cells represent a specific subtype of stem-like CD8+T with effector memory feature. Identification of the clinical significance and phenotype of gastric cancer infiltrating CXCR5+CD8+T provides a roadmap for patient stratification and trials of targeted therapies.

Impact of intratumoural CD73 expression on prognosis and therapeutic response in patients with gastric cancer.

AIM: CD73 overexpression has been reported in several malignancies and is considered to be a novel immune checkpoint. However, the role and significance of CD73 in gastric cancer (GC) still remain obscure. We aim to investigate the role of CD73 expression in predicting prognosis, shaping immune contexture and guiding therapeutic strategy in GC. METHODS: The study enrolled four independent cohorts with a total of 902 patients with GC. CD73 expression and immune contexture were examined by immunohistochemistry, single-sample gene set enrichment analysis and flow cytometry. Clinical outcomes of patient subgroups were evaluated using the Kaplan-Meier curves and Cox proportional hazard analysis. All statistical tests were two-sided. RESULTS: CD73 was identified as an independent adverse prognostic factor for survival in GC. CD73high tumours showed a specific microenvironment with more CD8+ T cell infiltration, but these CD8+ T cells displayed a dysfunctional phenotype. Furthermore, the CD73 (NT5E) mRNA level was associated with the Cancer Genome Atlas molecular subtypes, and NT5E high tumours showed significant fibroblast growth factor receptor 2 activation and vascular endothelial growth factor and receptor enrichment. In addition, CD73high tumours indicated better chemotherapeutic responsiveness to fluorouracil yet a worse objective response rate to pembrolizumab in GC. CONCLUSIONS: High CD73 expression indicated an immunoevasive contexture with CD8+ T cell dysfunction and represented an independent predictor for adverse clinical outcomes. As a potential immunotherapeutic target, CD73 could potentially be a novel biomarker for adjuvant chemotherapy, targeted therapies and immunotherapy. The crucial role of CD73 in the therapeutic landscape of GC needs further validation retrospectively and prospectively.

Immune inactivation by APOBEC3B enrichment predicts response to chemotherapy and survival in gastric cancer.

Apolipoprotein B mRNA editing enzyme catalytic polypeptide 3B (APOBEC3B) plays an important role in tumor mutagenesis. However, its clinical significance in gastric cancer (GC) remains largely unknown. We enrolled a total of 482 GC patients from Zhongshan Hospital, Fudan University for immunohistochemistry (IHC) staining to evaluate the prognostic and predictive values of APOBEC3B. Genomic and phenotypic datasets from the Cancer Genome Atlas (TCGA) and Asian Cancer Research Group (ACRG) cohort were downloaded for external validation and complementary bioinformatic analysis. Fresh specimens of additional 60 patients from Zhongshan Hospital, Fudan University were collected to detect CD8+ T cell phenotype with flow cytometry (FCM). The high expression of APOBEC3B indicated inferior overall survival (OS, P < .001 and P = .003) and disease-free survival (DFS, P < .001 and P < .001), yet superior therapeutic responsiveness to fluorouracil-based adjuvant chemotherapy (ACT) in TNM stage II patients. The tumor microenvironment (TME) of APOBEC3B-enriched tumors was characterized by reduced infiltration of tumor reactive CD8+ T cells expressing both effector molecules and immune checkpoints. APOBEC3B high CD8+ T cell high GC patients were most likely to benefit from ACT and PD-1 blockade. Our study demonstrates that APOBEC3B was an independent prognostic and predictive factor in GC. The potential interplay between APOBEC3B and CD8+ T cells merited further investigations.