A pan-cancer single-cell transcriptional atlas of tumor infiltrating myeloid cells.

Tumor-infiltrating myeloid cells (TIMs) are key regulators in tumor progression, but the similarity and distinction of their fundamental properties across different tumors remain elusive. Here, by performing a pan-cancer analysis of single myeloid cells from 210 patients across 15 human cancer types, we identified distinct features of TIMs across cancer types. Mast cells in nasopharyngeal cancer were found to be associated with better prognosis and exhibited an anti-tumor phenotype with a high ratio of TNF+/VEGFA+ cells. Systematic comparison between cDC1- and cDC2-derived LAMP3+ cDCs revealed their differences in transcription factors and external stimulus. Additionally, pro-angiogenic tumor-associated macrophages (TAMs) were characterized with diverse markers across different cancer types, and the composition of TIMs appeared to be associated with certain features of somatic mutations and gene expressions. Our results provide a systematic view of the highly heterogeneous TIMs and suggest future avenues for rational, targeted immunotherapies.

The phosphatase PAC1 acts as a T cell suppressor and attenuates host antitumor immunity.

Cancer cells subvert immune surveillance through inhibition of T cell effector function. Elucidation of the mechanism of T cell dysfunction is therefore central to cancer immunotherapy. Here, we report that dual specificity phosphatase 2 (DUSP2; also known as phosphatase of activated cells 1, PAC1) acts as an immune checkpoint in T cell antitumor immunity. PAC1 is selectively upregulated in exhausted tumor-infiltrating lymphocytes and is associated with poor prognosis of patients with cancer. PAC1hi effector T cells lose their proliferative and effector capacities and convert into exhausted T cells. Deletion of PAC1 enhances immune responses and reduces cancer susceptibility in mice. Through activation of EGR1, excessive reactive oxygen species in the tumor microenvironment induce expression of PAC1, which recruits the Mi-2ß nucleosome-remodeling and histone-deacetylase complex, eventually leading to chromatin remodeling of effector T cells. Our study demonstrates that PAC1 is an epigenetic immune regulator and highlights the importance of targeting PAC1 in cancer immunotherapy.

ReProMSig: an integrative platform for development and application of reproducible multivariable models for cancer prognosis supporting guideline-based transparent reporting.

Adequate reporting is essential for evaluating the performance and clinical utility of a prognostic prediction model. Previous studies indicated a prevalence of incomplete or suboptimal reporting in translational and clinical studies involving development of multivariable prediction models for prognosis, which limited the potential applications of these models. While reporting templates introduced by the established guidelines provide an invaluable framework for reporting prognostic studies uniformly, there is a widespread lack of qualified adherence, which may be due to miscellaneous challenges in manual reporting of extensive model details, especially in the era of precision medicine. Here, we present ReProMSig (Reproducible Prognosis Molecular Signature), a web-based integrative platform providing the analysis framework for development, validation and application of a multivariable prediction model for cancer prognosis, using clinicopathological features and/or molecular profiles. ReProMSig platform supports transparent reporting by presenting both methodology details and analysis results in a strictly structured reporting file, following the guideline checklist with minimal manual input needed. The generated reporting file can be published together with a developed prediction model, to allow thorough interrogation and external validation, as well as online application for prospective cases. We demonstrated the utilities of ReProMSig by development of prognostic molecular signatures for stage II and III colorectal cancer respectively, in comparison with a published signature reproduced by ReProMSig. Together, ReProMSig provides an integrated framework for development, evaluation and application of prognostic/predictive biomarkers for cancer in a more transparent and reproducible way, which would be a useful resource for health care professionals and biomedical researchers.

Multi-regional sequencing reveals the genetic and immune heterogeneity of non-cancerous tissues in gastric cancer.

Gastric cancer (GC) is one of the most heterogeneous tumors. However, research on normal tissue adjacent to the tumor (NAT) is very limited. We performed multi-regional omics sequencing on 150 samples to assess the genetic basis and immune microenvironment in NAT and matched primary tumor or lymph node metastases. NATs demonstrated different mutated genes compared with GC, and NAT genomes underwent independent evolution with low variant allele frequency. Mutation profiles were predominated by aging and smoking-associated signatures in NAT instead of signatures associated with genetic instability. Although the immune microenvironment within NATs shows substantial intra-patient heterogeneity, the proportion of shared TCR clones among NATs is five times higher than that of tumor regions. These findings support the notion that subclonal expansion is not pronounced in NATs. We also demonstrated remarkable intra-patient heterogeneity of GCs and revealed heterogeneity of focal amplification of CD274 (encoding PD-L1) that leads to differential expression. Finally, we identified that monoclonal seeding is predominant in GC, which is followed by metastasis-to-metastasis dissemination in individual lymph nodes. These results provide novel insights into GC carcinogenesis. © 2024 The Pathological Society of Great Britain and Ireland.

Dual roles of ß-arrestin 1 in mediating cell metabolism and proliferation in gastric cancer.

ß-Arrestin 1 (ARRB1) has been recognized as a multifunctional adaptor protein in the last decade, beyond its original role in desensitizing G protein-coupled receptor signaling. Here, we identify that ARRB1 plays essential roles in mediating gastric cancer (GC) cell metabolism and proliferation, by combining cohort analysis and functional investigation using patient-derived preclinical models. Overexpression of ARRB1 was associated with poor outcome of GC patients and knockdown of ARRB1 impaired cell proliferation both ex vivo and in vivo. Intriguingly, ARRB1 depicted diverse subcellular localizations during a passage of organoid cultures (7 d) to exert dual functions. Further analysis revealed that nuclear ARRB1 binds with transcription factor E2F1 triggering up-regulation of proliferative genes, while cytoplasmic ARRB1 modulates metabolic flux by binding with the pyruvate kinase M2 isoform (PKM2) and hindering PKM2 tetramerization, which reduces pyruvate kinase activity and leads to cellular metabolism shifts from oxidative phosphorylation to aerobic glycolysis. As ARRB1 localization was shown mostly in the cytoplasm in human GC samples, therapeutic potential of the ARRB1-PKM2 axis was tested, and we found tumor proliferation could be attenuated by the PKM2 activator DASA-58, especially in ARRB1high organoids. Together, the data in our study highlight a spatiotemporally dependent role of ARRB1 in mediating GC cell metabolism and proliferation and implies reactivating PKM2 may be a promising therapeutic strategy in a subset of GC patients.

Tumor-infiltrating immune cell profiles and changes associate with additional trastuzumab in preoperative chemotherapy for patients with HER2-positive gastric cancer.

BACKGROUND: HER2(+) gastric cancer (GC) can benefit from trastuzumab. However, the impact of additional trastuzumab in preoperative treatment on immune cells remains largely unknown. METHODS: In cohort I, immune cells were detected by immunohistochemistry in 1321 patients. Then 88 HER2(+) patients received preoperative therapy were collected as cohort II. Immune cell profiles and changes were analyzed in paired pre- and post-operative specimens using multiple immunohistochemistry staining. RESULTS: In the treatment-naive GC patients (n = 1002), CD3+ and CD8+ T cell infiltration was significantly lower in the HER2(+) GC patients together with higher FoxP3+ T cells compared with HER2(-). However, FoxP3+ T and CD20+ B cell infiltration was significantly higher in HER2(+) GC after neoadjuvant chemotherapy (n = 319). The trastuzumab-exposed group had higher CD8+ T and lower FoxP3+ T cell infiltration and CD8+ T cell was even more significant in responders. Additionally, tertiary lymphoid structure (TLS) density increased in invasion margin of residual tumors. Patients with lower TLS in the tumor core or lower FoxP3+ T cells had better overall survival in the trastuzumab-exposed group. CONCLUSION: Addition of trastuzumab modulates the immune microenvironment, suggesting the potential mechanism of the favorable outcome of anti-HER2 therapy and providing a theoretical rationale for the combinational immunotherapy in resectable HER2(+) GC patients.

Pre- and Post-treatment Double-Sequential-Point Dynamic Radiomic Model in the Response Prediction of Gastric Cancer to Neoadjuvant Chemotherapy: 3-Year Survival Analysis.

BACKGROUND: Prognosis prediction of patients with gastric cancer after neoadjuvant chemotherapy is suboptimal. This study aims to develop and validate a dynamic radiomic model for prognosis prediction of patients with gastric cancer on the basis of baseline and posttreatment features. PATIENTS AND METHODS: This single-center cohort study included patients with gastric adenocarcinoma treated with neoadjuvant chemotherapy from June 2009 to July 2015 in the Gastrointestinal Cancer Center of Peking University Cancer Hospital. Their clinicopathological data, pre-treatment and post-treatment computed tomography (CT) images, and pathological reports were retrieved and analyzed. Four prediction models were developed and validated using tenfold cross-validation, with death within 3 years as the outcome. Model discrimination was compared by the area under the curve (AUC). The final radiomic model was evaluated for calibration and clinical utility using Hosmer-Lemeshow tests and decision curve analysis. RESULTS: The study included 205 patients with gastric adenocarcinoma [166 (81%) male; mean age 59.9 (SD 10.3) years], with 71 (34.6%) deaths occurring within 3 years. The radiomic model alone demonstrated better discrimination than the pathological T stage (ypT) stage model alone (cross-validated AUC 0.598 versus 0.516, P = 0.009). The final radiomic model, which incorporated both radiomic and clinicopathological characteristics, had a significantly higher cross-validated AUC (0.769) than the ypT stage model (0.516), the radiomics alone model (0.598), and the ypT plus other clinicopathological characteristics model (0.738; all P < 0.05). Decision curve analysis confirmed the clinical utility of the final radiomic model. CONCLUSIONS: The developed radiomic model had good accuracy and could be used as a decision aid tool in clinical practice to differentiate prognosis of patients with gastric cancer.

Long-term outcomes of laparoscopic versus open total gastrectomy in patients with advanced gastric cancer after neoadjuvant chemotherapy: a retrospective cohort study.

BACKGROUND: This study was conducted to investigate the long-term outcomes of laparoscopic total gastrectomy (LTG) versus open total gastrectomy (OTG) in patients with advanced gastric cancer (AGC) after neoadjuvant chemotherapy (NACT). METHODS: Patients with AGC who received NACT before surgery were enrolled in either the LTG or OTG group. Propensity score matching (PSM) (1:2) was performed between the two groups based on the propensity score using a 0.15 calliper width. Three-year overall survival (OS) and disease-free survival (DFS) were compared between these two groups before and after PSM. OS and DFS rates were calculated by the Kaplan‒Meier method, and any differences in survival were evaluated with a log-rank test. Univariate and multivariate Cox proportional hazards analyses were used to estimate the simultaneous effects of prognostic factors on survival and the hazard ratio (HR) between LTG and OTG patients. RESULTS: A total of 144 patients completed the follow-up, with 24 patients in the LTG group and 120 patients in the OTG group. After a mean follow-up of 64.40 months, there were no significant differences in the 3-year OS or DFS rates between the two groups before (P = 0.453 and P = 0.362, respectively) or after PSM (P = 0.972 and P = 0.884, respectively). Multivariate Cox proportional hazards analysis indicated that ypN stage was an independent risk factor for worse OS (P = 0.013). CONCLUSIONS: This study showed that LTG with D2 lymphadenectomy performed by an experienced surgical team resulted in comparable 3-year OS and DFS compared with OTG in patients with AGC after NACT. TRIAL REGISTRATION: This study is not registered.

Safety and short-term outcomes of a modified valvuloplastic esophagogastrostomy versus gastric tube anastomosis after laparoscopy-assisted proximal gastrectomy: a retrospective cohort study.

BACKGROUND: There is no optimal reconstruction method after proximal gastrectomy. The valvuloplastic esophagogastrostomy can reduce postoperative reflux esophagitis, but it is technically complex with a long operation time. The gastric tube anastomosis is technically simple, but the incidences of reflux esophagitis and anastomotic stricture are higher. METHODS: We have devised a modified valvuloplastic esophagogastrostomy after laparoscopy-assisted proximal gastrectomy (LAPG), the arch-bridge anastomosis. After reviewing our prospectively maintained gastric cancer database, 43 patients who underwent LAPG from November 2021 to April 2023 were included in this cohort study, with 25 patients received the arch-bridge anastomosis and 18 patients received gastric tube anastomosis. The short-term outcomes were compared between the two groups to evaluate the efficacy of the arch-bridge anastomosis. Reporting was consistent with the STROCSS 2021 guideline. RESULTS: The median operation time was 180 min in the arch-bridge group, significantly shorter than the gastric tube group (p = 0.003). In the arch-bridge group, none of the 25 patients experienced anastomotic leakage, while one patient (4%) experienced anastomotic stricture requiring endoscopic balloon dilation. The postoperative length of stay was shorter in the arch-bridge group (9 vs. 11, p = 0.034). None of the patients in the arch-bridge group experienced gastroesophageal reflux and used proton pump inhibitor (PPI), while four (22.2%) patients in the gastric tube group used PPI (p = 0.025). The incidence of reflux esophagitis (Los Angeles grade B or more severe) by endoscopy was lower in the arch-bridge group (0% vs. 25.0%). CONCLUSION: The arch-bridge anastomosis is a safe, time-saving, and feasible reconstruction method. It can reduce postoperative reflux and anastomotic stricture incidences in a selected cohort of patients undergoing laparoscopy-assisted proximal gastrectomy.

In-Depth Comparison of Matrigel Dissolving Methods on Proteomic Profiling of Organoids.

Patient-derived organoids recently emerged as promising ex vivo 3D culture models recapitulating histological and molecular characteristics of original tissues, thus proteomic profiling of organoids could be valuable for function investigation and clinical translation. However, organoids are usually cultured in murine Matrigel (served as scaffolds and matrix), which brings an issue to separate organoids from Matrigel. Because of the complex compositions of Matrigel and thousands of identical peptides shared between Matrigel and organoids, insufficiently dissolved Matrigel could influence proteomic analysis of organoids in multiple ways. Thus, how to dissolve Matrigel matrix and recovery organoid cells efficiently is vital for sample preparation. Here, we comprehensively compared three popular Matrigel dissolving methods (cell recovery solution, dispase, and PBS-EDTA buffer) and investigated the effect of undissolved Matrigel proteins on proteomic profiles of organoids. By integrative analysis of label-free proteomes of Matrigel and stable isotope labeling by amino acids in cell culture proteomes of organoids collected by three methods, respectively, we found that dispase showed an optimal efficiency, with the highest peptide yield and the highest incorporation ratio of stable isotope labeling by amino acids in cell culture labels (97.1%), as well as with the least potential Matrigel contaminants. To help analysis of proteomic profiles of organoids collected by the other two methods, we identified 312 high-confidence Matrigel contaminants, which could be filtered out to attenuate Matrigel interference with minimal loss of biological information. Together, our study identifies bioinformatics and experimental approaches to eliminate interference of Matrigel contaminants efficiently, which will be valuable for basic and translational proteomic research using organoid models.

Genomic characterization of peritoneal lavage cytology-positive gastric cancer.

Objective: Positive peritoneal lavege cytology (CY1) gastric cancer is featured by dismal prognosis, with high risks of peritoneal metastasis. However, there is a lack of evidence on pathogenic mechanism and signature of CY1 and there is a continuous debate on CY1 therapy. Therefore, exploring the mechanism of CY1 is crucial for treatment strategies and targets for CY1 gastric cancer. Methods: In order to figure out specific driver genes and marker genes of CY1 gastric cancer, and ultimately offer clues for potential marker and risk assessment of CY1, 17 cytology-positive gastric cancer patients and 31 matched cytology-negative gastric cancer patients were enrolled in this study. The enrollment criteria were based on the results of diagnostic laparoscopy staging and cytology inspection of exfoliated cells. Whole exome sequencing was then performed on tumor samples to evaluate genomic characterization of cytology-positive gastric cancer. Results: Least absolute shrinkage and selection operator (LASSO) algorithm identified 43 cytology-positive marker genes, while MutSigCV identified 42 cytology-positive specific driver genes. CD3G and CDKL2 were both driver and marker genes of CY1. Regarding mutational signatures, driver gene mutation and tumor subclone architecture, no significant differences were observed between CY1 and negative peritoneal lavege cytology (CY0). Conclusions: There might not be distinct differences between CY1 and CY0, and CY1 might represent the progression of CY0 gastric cancer rather than constituting an independent subtype. This genomic analysis will thus provide key molecular insights into CY1, which may have a direct effect on treatment recommendations for CY1 and CY0 patients, and provides opportunities for genome-guided clinical trials and drug development.

Transcriptome profiling of patient-derived tumor xenografts suggests novel extracellular matrix-related signatures for gastric cancer prognosis prediction.

BACKGROUND: A major obstacle to the development of personalized therapies for gastric cancer (GC) is the prevalent heterogeneity at the intra-tumor, intra-patient, and inter-patient levels. Although the pathological stage and histological subtype diagnosis can approximately predict prognosis, GC heterogeneity is rarely considered. The extracellular matrix (ECM), a major component of the tumor microenvironment (TME), extensively interacts with tumor and immune cells, providing a possible proxy to investigate GC heterogeneity. However, ECM consists of numerous protein components, and there are no suitable models to screen ECM-related genes contributing to tumor growth and prognosis. We constructed patient-derived tumor xenograft (PDTX) models to obtain robust ECM-related transcriptomic signatures to improve GC prognosis prediction and therapy design. METHODS: One hundred twenty two primary GC tumor tissues were collected to construct PDTX models. The tumorigenesis rate and its relationship with GC prognosis were investigated. Transcriptome profiling was performed for PDTX-originating tumors, and least absolute shrinkage and selection operator (LASSO) Cox regression analysis was applied to extract prognostic ECM signatures and establish PDTX tumorigenicity-related gene (PTG) scores. The predictive ability of the PTG score was validated using two independent cohorts. Finally, we combined PTG score, age, and pathological stage information to establish a robust nomogram for GC prognosis prediction. RESULTS: We found that PDTX tumorigenicity indicated a poor prognosis in patients with GC, even at the same pathological stage. Transcriptome profiling of PDTX-originating GC tissues and corresponding normal controls identified 383 differentially expressed genes, with enrichment of ECM-related genes. A robust prognosis prediction model using the PTG score showed robust performance in two validation cohorts. A high PTG score was associated with elevated M2 polarized macrophage and cancer-associated fibroblast infiltration. Finally, combining the PTG score with age and TNM stage resulted in a more effective prognostic model than age or TNM stage alone. CONCLUSIONS: We found that ECM-related signatures may contribute to PDTX tumorigenesis and indicate a poor prognosis in GC. A feasible survival prediction model was built based on the PTG score, which was associated with immune cell infiltration. Together with patient ages and pathological TNM stages, PTG score could be a new approach for GC prognosis prediction.

PINA 3.0: mining cancer interactome.

Protein-protein interactions (PPIs) are crucial to mediate biological functions, and understanding PPIs in cancer type-specific context could help decipher the underlying molecular mechanisms of tumorigenesis and identify potential therapeutic options. Therefore, we update the Protein Interaction Network Analysis (PINA) platform to version 3.0, to integrate the unified human interactome with RNA-seq transcriptomes and mass spectrometry-based proteomes across tens of cancer types. A number of new analytical utilities were developed to help characterize the cancer context for a PPI network, which includes inferring proteins with expression specificity and identifying candidate prognosis biomarkers, putative cancer drivers, and therapeutic targets for a specific cancer type; as well as identifying pairs of co-expressing interacting proteins across cancer types. Furthermore, a brand-new web interface has been designed to integrate these new utilities within an interactive network visualization environment, which allows users to quickly and comprehensively investigate the roles of human interacting proteins in a cancer type-specific context. PINA is freely available at https://omics.bjcancer.org/pina/.

Performance of different colorectal cancer screening strategies: a long-term passive follow-up population-based screening program in Beijing, China.

BACKGROUND: We aimed to assess the performance of the risk assessment questionnaire and fecal immunochemical test (FIT) in a population-based colorectal cancer (CRC) screening program to provide timely evidence for tailored screening strategies in China. METHODS: This analysis was conducted using data from Beijing Cancer Screening Prospective Cohort Study (BCSPCS). A risk assessment questionnaire and FIT were selected as the primary screening methods, and participants with any positive results were referred to undergo a diagnostic colonoscopy. RESULTS: From 2015 to 2020, 148,636 Beijing residents aged 40-69 years were invited from designated communities, with 147,807 finishing the risk assessment questionnaire and 115,606 (78.2%) completing the FIT. Among the 42,969 (29.1%) high-risk CRC participants, 23,824 (55.4%) underwent colonoscopy. One year after enrollment, all subjects were linked to the Beijing Cancer Registry (BCR) database and 241 cases of CRC were confirmed. The CRC incidence rate was 58.2/100,000 for the low-risk arm and 418.9/100,000 for the high-risk arm. For participants who underwent colonoscopy, 91 CRC cases were detected, with a detection rate of 91.9% and 63.7% of them were early-stage cases. Furthermore, the sensitivities of utilizing the risk assessment questionnaire alone, FIT alone, combined risk assessment questionnaire and FIT were 75.7%, 50.1%, and 95.1%, and the specificities were 75.3%, 87.3%, and 70.7%, respectively. CONCLUSION: The Beijing CRC screening program can effectively detect early-onset CRC; however, the compliance with colonoscopy still needs to be improved.

Efficacy of chemotherapy versus surgery as initial treatment for gastric cancer with positive peritoneal cytology.

BACKGROUND: The prognosis of gastric cancer (GC) patients with positive peritoneal cytology (CY1) without other distant metastasis is poor, and there are no standard treatment strategies. Our study aimed to compare the survival outcomes of CY1 GC patients receiving chemotherapy or surgery as initial treatment. METHODS: From February 2017 to January 2020, clinical and pathological data of patients diagnosed with CY1 GC without other distant metastasis in the Peking University Cancer Hospital was reviewed. Patients were divided into two groups: chemotherapy-initial group and surgery-initial group. In chemotherapy-initial group, patients received preoperative chemotherapy initially. According to the treatment response, the patients were divided into three subgroups: conversion gastrectomy group, palliative gastrectomy group, and further systematic chemotherapy group. In surgery-initial group, patients underwent gastrectomy followed by postoperative chemotherapy. RESULTS: A total of 96 CY1 GC patients were included with 48 patients in each group. In chemotherapy-initial group, preoperative chemotherapy yielded an objective response rate of 20.8% and disease control rate of 87.5%. Conversion to CY0 after preoperative chemotherapy was obtained in 24 (50%) patients. The median overall survival was 36.1 months in chemotherapy-initial group and 29.7 months in surgery-initial group (p = 0.367). The median progression-free survival was 18.1 months in chemotherapy-initial group and 16.1 months in surgery-initial group (p = 0.861). The 3-year overall survival rates were 50.0% and 47.9%, respectively. In chemotherapy-initial group, twenty-four patients who converted to CY0 by preoperative chemotherapy and received surgery obtained a significantly better prognosis. The median overall survival was still not reached in these patients. CONCLUSION: There was no significant difference in survival outcomes between chemotherapy-initial group and surgery-initial group. CY1 GC patients who converted to CY0 by preoperative chemotherapy and received radical surgery could obtain a favorable long-term prognosis. Further investigation should focus on preoperative chemotherapy to eliminate peritoneal cancer cell. TRIAL REGISTRATION: This study is retrospectively registered.

Activated Leukocyte Cell Adhesion Molecule (ALCAM), a Potential 'Seed' and 'Soil' Receptor in the Peritoneal Metastasis of Gastrointestinal Cancers.

Activated Leukocyte Cell Adhesion Molecule (ALCAM/CD166) is a cell-cell adhesion protein conferring heterotypic and homotypic interactions between cells of the same type and different types. It is aberrantly expressed in various cancer types and has been shown to be a regulator of cancer metastasis. In the present study, we investigated potential roles of ALCAM in the peritoneal transcoelomic metastasis in gastrointestinal cancers, a metastatic type commonly occurred in gastro-intestinal and gynaecological malignancies and resulting in poor clinical outcomes. Specifically, we studied whether ALCAM acts as both a 'seed' receptor in these tumour cells and a 'soil' receptor in peritoneal mesothelial cells during cancer metastasis. Gastric cancer and pancreatic cancer tissues with or without peritoneal metastasis were compared for their levels of ALCAM expression. The impact of ALCAM expression in these tumours was also correlated to the patients' clinical outcomes, namely peritoneal metastasis-free survival. In addition, cancer cells of gastric and pancreatic origins were used to create cell models with decreased or increased levels of ALCAM expression by genetic knocking down or overexpression, respectively. Human peritoneal mesothelial cells were also genetically transfected to generate cell models with different profiles of ALCAM expression. These cell models were used in the tumour-mesothelial interaction assay to assess if and how the interaction was influenced by ALCAM. Both gastric and pancreatic tumour tissues from patients who developed peritoneal metastases had higher levels of ALCAM transcript than those without. Patients who had tumours with high levels of ALCAM had a much shorter peritoneal metastasis free survival compared with those who had low ALCAM expression (p = 0.006). ALCAM knockdown of the mesothelial cell line MET5A rendered the cells with reduced interaction with both gastric cancer cells and pancreatic cancer cells. Likewise, levels of ALCAM in both human gastric and pancreatic cancer cells were also a determining factor for their adhesiveness to mesothelial cells, a process that was likely to be triggered the phosphorylation of the SRC kinase. A soluble ALCAM (sALCAM) was found to be able to inhibit the adhesiveness between cancer cells and mesothelial cells, mechanistically behaving like a SRC kinase inhibitor. ALCAM is an indicator of peritoneal metastasis in both gastric and pancreatic cancer patients. It acts as not only a potential peritoneal 'soil' receptor of tumour seeding but also a 'soil' receptor in peritoneal mesothelial cells during cancer metastasis. These findings have an important therapeutic implication for treating peritoneal transcoelomic metastases.

PTPRD/PTPRT mutation correlates to treatment outcomes of immunotherapy and immune landscape in pan-cancers.

Objective: PTPRD and PTPRT are phosphatases of the JAK-STAT pathway related to immunotherapy. However, the role and mechanism of PTPRD and PTPRT mutations in multiple cancers remains unclear. Methods: Clinical data and PTPRD/PTPRT mutation information from 12 cohorts were collected and classified as a discovery cohort and three validation cohorts. The association between PTPRD/PTPRT mutations and immunotherapeutic efficacy was analyzed. Then, the association between PTPRD/PTPRT mutation and immune profiles was analyzed using The Cancer Genome Atlas (TCGA) cohort. Results: A total of 2,392 patients across 20 cancer types were included in this study. Our results showed that patients harboring PTPRD/PTPRT mutation, especially co-mutations, had a significantly elevated response rate to immunotherapy in multiple cancers. Patients with PTPRD/PTPRT mutation had a higher objective response rate (ORR) (P=0.002), longer overall survival (OS) (P=0.005) and progression-free survival (PFS) (P=0.038). Importantly, the above findings were further verified in validation cohorts. In addition, we found that the PTPRD/PTPRT co-mutations (co-mut) subgroup exhibited an immune-activated phenotype, the wild-type subgroup tended to have an immune-desert phenotype, and the uni-mutation (uni-mut) subgroup might have an immune-mixed phenotype. Our further analyses suggested that combining programmed cell death ligand 1 (PD-L1) expression and PTPRD/PTPRT mutation can be used to screen patients who may benefit from immunotherapy. Conclusions: PTPRD/PTPRT mutation could serve as a potential predictive biomarker for cancer immunotherapy.

Exploration and optimization of surgical techniques for laparoscopic transhiatal lower mediastinal lymph node dissection for adenocarcinoma of esophagogastric junction: A prospective IDEAL 2a study with qualitative design.

Objective: To explore the change and feasibility of surgical techniques of laparoscopic transhiatal (TH)-lower mediastinal lymph node dissection (LMLND) for adenocarcinoma of the esophagogastric junction (AEG) according to Idea, Development, Exploration, Assessment, and Long-term follow-up (IDEAL) 2a standards. Methods: Patients diagnosed with AEG who underwent laparoscopic TH-LMLND were prospectively included from April 14, 2020, to March 26, 2021. Clinical and pathological information as well as surgical outcomes were quantitatively analyzed. Semistructured interviews with the surgeon after each operation were qualitatively analyzed. Results: Thirty-five patients were included. There were no cases of transition to open surgery, but three cases involved combination with transthoracic surgery. In qualitative analysis, 108 items under three main themes were detected: explosion, dissection, and reconstruction. Revised instruction was subsequently designed according to the change in surgical technique and the cognitive process behind it. Three patients had anastomotic leaks postoperatively, with one classified as Clavien-Dindo IIIa. Conclusions: The surgical technique of laparoscopic TH-LMLND is stable and feasible; further IDEAL 2b research is warranted.

Double-tract reconstruction is superior to esophagogastrostomy in controlling reflux esophagitis and enhancing quality of life after proximal gastrectomy: Results from a prospective randomized controlled clinical trial in China.

Objective: The aim of this study was to prospectively compare double-tract reconstruction (DTR) and esophagogastrostomy (EG) after proximal gastrectomy (PG) regarding the incidence of reflux esophagitis, quality of life (QOL), nutritional status and surgical safety. Methods: This study was a randomized controlled trial. Patients eligible for PG were enrolled and randomly assigned to the EG group and DTR group. The characteristics of patients, parameters for surgical safety, incidence of reflux esophagitis, nutrition status and QOL were collected and compared between the two groups. Univariate analysis and multivariate analysis were performed to determine the significant factors affecting the incidence of reflux esophagitis after PG. Results: Thirty-seven patients of the EG group and 36 patients of the DTR group were enrolled. The incidence of reflux esophagitis was significantly lower in the DTR group than in the EG group (8.3% vs. 32.4%, P=0.019). The DTR group demonstrated a more favorable QOL than the EG group after PG. The nutritional status was balanced within the EG group and the DTR group. The operation time was longer in the DTR group than in the EG group (191 min vs. 221 min, P=0.001), while surgical safety was similar in the two groups. Conclusions: Our research demonstrated that DTR is superior to EG after PG in terms of the incidence of reflux esophagitis and provides a more satisfactory QOL without increasing surgical complications or sacrificing nutritional status.

Interpretable tumor differentiation grade and microsatellite instability recognition in gastric cancer using deep learning.

Gastric cancer possesses great histological and molecular diversity, which creates obstacles for rapid and efficient diagnoses. Classic diagnoses either depend on the pathologist's judgment, which relies heavily on subjective experience, or time-consuming molecular assays for subtype diagnosis. Here, we present a deep learning (DL) system to achieve interpretable tumor differentiation grade and microsatellite instability (MSI) recognition in gastric cancer directly using hematoxylin-eosin (HE) staining whole-slide images (WSIs). WSIs from 467 patients were divided into three cohorts: the training cohort with 348 annotated WSIs, the testing cohort with 88 annotated WSIs, and the integration testing cohort with 31 original WSIs without tumor contour annotation. First, the DL models comprehensibly achieved tumor differentiation recognition with an F1 values of 0.8615 and 0.8977 for poorly differentiated adenocarcinoma (PDA) and well-differentiated adenocarcinoma (WDA) classes. Its ability to extract pathological features about the glandular structure formation, which is the key to distinguishing between PDA and WDA, increased the interpretability of the DL models. Second, the DL models achieved MSI status recognition with a patient-level accuracy of 86.36% directly from HE-stained WSIs in the testing cohort. Finally, the integrated end-to-end system achieved patient-level MSI recognition from original HE staining WSIs with an accuracy of 83.87% in the integration testing cohort with no tumor contour annotation. The proposed system, therefore, demonstrated high accuracy and interpretability, which can potentially promote the implementation of artificial intelligence healthcare.