Efficacy of MAGE-A4 long peptide as a universal immunoprevention cancer vaccine.

BACKGROUND: The clinical application of peptide vaccines in tumor immunotherapy holds significant promise. Peptide-based tumor vaccines are currently subject to certain limitations in clinical trials, including the challenge of inducing a sustained response from CD4+ T helper cells and cytotoxic T lymphocytes (CTL), as well as human leukocyte antigen (HLA) restrictions. METHODS: Through the utilization of biological information methodology, a screening process was conducted to identify three potential long peptides that are specifically targeted by the MAGE-A4 antigen. The candidate long peptides were subjected to in vitro testing using human peripheral blood lymphocytes as samples to evaluate their immunogenicity and immune function. The antitumor properties and preliminary mechanism of the long peptide vaccine were investigated through the use of a mouse model designed for the prevention of triple negative breast cancer (TNBC). RESULTS: Three predicted multi-epitope long peptides targeting MAGE-A4 have shown to have a strong immunogenicity, with a total positive rate of 72% across different HLA subtypes in Chinese populations. they can also increase the levels of the costimulatory factor CD137 and tumor necrosis factor-alpha (TNF-α), activate T cells, and boost the cytotoxic activity. Results from an animal study have revealed that the long-peptide vaccine, both on its own and in combination with R848, has displayed impressive anti-tumor and target-specific capabilities. Moreover, it has the ability to increase the expression of effector memory T cells and central memory T cells. CONCLUSIONS: This study was the first to screen three multi-epitope long peptides targeting MAGE-A4 and assess their immunogenicity, immune function, and potential as adjuvant peptides. The results showed that the MAGE-A4 long peptide vaccine can be used as a novel immunoprophylaxis method to prevent TNBC. Moreover, the proposed development model is capable of screening multiple target antigens, which lead to its clinical application.

Prevalence and Associations of Beta2-Microglobulin Mutations in MSI-H/dMMR Cancers.

Microsatellite instability (MSI) has emerged as an important predictor of sensitivity for immunotherapy-based strategies. ß-2-Microglobulin (B2M) contains microsatellites within the coding regions and is prone to somatic changes in MSI/mismatch repair deficiency (MSI/dMMR) tumors. To delineate prevalence and associations of B2M mutations in MSI-H/dMMR cancers, we investigated the mutational profile of B2M and clinical and pathological features in gastric cancer (GC), colorectal cancer (CRC), and endometrial cancer (EC) with a high incidence of microsatellite instability-high (MSI-H)/dMMR. Formalin-fixed paraffin-embedded (FFPE) tumor tissues along with matched normal tissues were collected from 108 MSI/dMMR patients with GC, CRC, and EC. Genomic profiling of tissue and blood samples were assessed next-generation sequencing (NGS). Immunohistochemistry (IHC) was used to examine the presence or absence of B2M protein. Alternations in the exonic microsatellite regions of B2M were observed at various but high frequencies (57.5% in CRC, 23.9% in GC, and 13.6% in EC) and in different forms. NGS assay revealed that genes involved in chromatin regulation, the PI3K pathway, the WNT pathway, and mismatch repair were extensively altered in the MSI-H cohort. Signature 6 and 26, 2 of 4 mutational signatures associated with defective DNA mismatch repair, featured with high numbers of small insertion/deletions (INDEL) dominated in all 3 types of cancer. Alternations in the exonic microsatellite regions of B2M were observed at various but high frequencies (57.5% in CRC, 23.9% in GC, and 13.6% in EC) and in different forms. Tumor mutational burden (TMB) was significantly higher in the patients carrying MSI-H/dMMR tumors with B2M mutation than that in patients with wild-type B2M (P = .026).The frame shift alteration occurring at the exonic microsatellite sties caused loss of function of B2M gene. In addition, a case with CRC carrying indels in B2M gene resisted the ICI treatment was reported. In conclusion, patients carrying MSI-H/dMMR tumors with B2M mutation showed significantly higher TMB. Prescription of ICIs should be thoroughly evaluated for these patients.

FGFR2 alteration as a potential therapeutic target in poorly cohesive gastric carcinoma.

BACKGROUND: Poorly cohesive (PC) is a unique histologic subtype of gastric cancer (GC), with an increasing incidence in recent years. However, the molecular characteristics and therapeutic targets of PC GC are not yet well studied and there are no effective therapies for these patients. METHODS: Formalin fixed paraffin embedded (FFPE) samples of 556 GC patients, including 64 PC GC, were collected for next-generation sequencing (NGS). Clinical characteristics and genomic profiling were analyzed. FGFR2 expression was detected by quantitative real time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC). FGFR2 inhibitors response was studied in vitro. RESULTS: Among 556 GC patients, PC GC patients were younger (P = 0.004), had lower tumor mutation burden (TMB-L) (P = 0.001) than non-PC GC. The top 10 most frequently mutated genes in PC GC were TP53 (48%), CDH1 (31%), ARID1A (14%), FGFR2 (14%), ERBB2 (9%), CDKN2A (9%), FGF3 (8%), LRP1B (9%), FGF19 (8%) and FGF4 (8%). Noticeably, FGFR2 is more frequently mutated than non-PC GC (14% vs. 6%, P = 0.037), including copy number variants (CNVs, 12.5%) and gene rearrangements (3.1%, FGFR2/VTI1A and FGFR2/TACC2). Former studies have confirmed that gain of copy number could increase FGFR2 expression and sensitivity to FGFR2 inhibitors in GC. However, no research has verified the function of FGFR2 rearrangements in GC. Our results showed that cell lines of GC transfected with TACC2-FGFR2 fusion had increased mRNA and protein expression of FGFR2, and were more sensitive to FGFR2 inhibitors. FGFR2 inhibitors might be a new therapeutic target for PC GC. In addition, we found patients of PC GC harboring gene rearrangements (n = 9) had poorer overall survival (OS) in comparison with patients without any gene rearrangement (n = 19) (16.0 months vs 21.0 months, P = 0.043). Gene rearrangement might be an adverse prognostic factor for PC GC patients. CONCLUSIONS: FGFR2 alterations were recurrent in PC GC and FGFR2 inhibitors might be a new therapeutic target for PC GC.

Prognostic Nomograms Based on Three Lymph Node Classification Systems for Resected Gastric Adenocarcinoma: A Large Population-Based Cohort Study and External Validation.

BACKGROUNDS: The optimal lymph node classification system for prognostic assessment in gastric adenocarcinoma (GAC) patients who undergo lymph node dissection remains unclear. Therefore, this study aimed to compare prognostic nomograms based on AJCC N stage, lymph node ratio (LNR), and log odds of metastatic lymph nodes (LODDS) to evaluate the prognosis and differentiate risk subgroups of patients with resected GAC. PATIENTS AND METHODS: We collected 4633 patients with resected stage I-III GAC receiving chemotherapy from the Surveillance, Epidemiology, and End Results (SEER) database between 2004 and 2015. Independent prognostic factors were selected by Cox regression analyses, based on which nomograms were constructed. External validation was performed in 228 cases from Nanjing Drum Tower Hospital. Kaplan-Meier survival analysis was used to evaluate the effect of postoperative radiotherapy (PORT) for different lymph node classifications. RESULTS: Multivariate analysis indicated that age, grade, primary site, T stage, N stage, LNR, LODDS, and radiotherapy were independent predictors. Good discrimination power and high consistency of calibration plots were obtained from the LODDS system nomogram. The LODDS classification could more precisely differentiate risk subgroups and improve the discrimination of the resected GAC prognosis. A user-friendly webserver of LODDS system was built based on the nomogram for convenient clinical application. CONCLUSIONS: The LODDS seems to be the most reliable lymph node classification in predicting the prognosis of patients with resected GAC and should be recommended in clinical prognostic assessment. Incorporating LODDS into the staging system will enable clinicians to more accurately predict prognosis and guide radiotherapy regimen decisions.

MET overexpression and amplification define a distinct molecular subgroup for targeted therapies in gastric cancer.

BACKGROUND: Currently, only trastuzumab, ramucirumab, and apatinib effectively treat gastric cancer. Thus, additional novel targets are required for this disease. METHODS: We investigated the immunohistochemical and fluorescence in situ hybridization expression of MET, ROS1, and ALK in four gastric cell lines and a cohort of 98 gastric cancer patients. Crizotinib response was studied in vitro and in vivo. RESULTS: Crizotinib potently inhibited in vitro cell growth in only one cell line, which also showed MET amplification. A positive correlation between crizotinib sensitivity and MET overexpression was observed (P = 0.045) in the histoculture drug response assay. Meanwhile, patient-derived tumor xenograft mouse models transplanted with tissues with higher MET protein expression displayed a highly selective sensitivity to crizotinib. In the 98 patients, MET overexpression was found in 42 (42.9 %) and MET was amplified in 4 (4.1 %). ROS1 and ALK overexpression were found in 25 (25.5 %) and 0 patients, respectively. However, none of the patients screened harbored ALK or ROS1 rearrangements. No significant association was found between overall survival and MET or ROS1 status. We also observed a stage IV gastric cancer patient with MET amplification who experienced tumor shrinkage and clinical benefit after 3 weeks of crizotinib as fourth-line treatment. CONCLUSIONS: Crizotinib may induce clinically relevant anticancer effects in MET-overexpressed or MET-amplified gastric cancer patients.

Necroptosis Related Genes Predict Prognosis and Therapeutic Potential in Gastric Cancer.

The clinical significance of necroptosis in gastric cancer (GC) has yet to be fully elucidated. The purpose of our study was to identify a necroptosis-relevant gene and to establish a prediction model to estimate the prognosis and therapeutic potential in GC. Here, we explored the expression profile of 76 necroptosis-related genes in TCGA-STAD patients. A six-gene risk score prediction model was established via regression analysis of the least absolute shrinkage and selection operator (LASSO) and validated in a separate cohort. Patients were separated into low- or high-risk groups according to the median risk score. We then compared and analyzed the biological process characteristics of two risk groups. Additionally, cell-to-cell communications and metabolic activity were analyzed in a single-cell solution. The in vitro experiments were conducted to explore the biological functions and drug sensitivity of necroptosis-related genes in gastric cancer. Our results identified that compared with the low-risk group, the high-risk group was associated with a higher clinical stage or grade and a worse prognosis. In addition, the low-risk group had higher levels of immunity and immune cell infiltration. Necroptosis was triggered by the TNF pathway in myeloid cells and the glycolysis pathway was altered. Necroptosis-related genes modulated the cell function, including proliferation and migration in vitro. Furthermore, the potential drugs' sensitivity was higher in the low-risk subgroup. These findings could facilitate a better understanding and improve the treatment potential and prognosis of GC patients.

Antigen-Specific T Cell Immunotherapy Targeting Claudin18.2 in Gastric Cancer.

T cell-based immunotherapy has led to many breakthroughs in the treatment of solid tumors. In this study, we found that membrane protein Claudin18.2 was a promising antigen in T cell-based immunotherapy for gastric cancer (GC). Firstly, we identified five HLA-A*0201- and seven HLA-A*1101-restricted T cell epitopes of Claudin18.2. Peripheral blood mononuclear cells (PBMCs) stimulated by Claudin18.2 peptides showed progressive anti-tumor ability and higher effective cytokine secretion than unstimulated PBMCs in vitro. In total, 81.8% of GC patients were Claudin18.2-positive by immunohistochemical (IHC) detection, and a positive correlation between Claudin18.2 expression and peptide reactivity (p = 0.002) was found. Clinicopathological features analyses demonstrated that Claudin18.2 expression did not correlate with gender, age, stage or Lauren classification. Survival analysis showed that a longer median progression-free survival (mPFS) was not related to peptide reactivity (p = 0.997), but related to a lower Claudin18.2 expression level (p = 0.047). These findings establish a foundation for the clinical application of Claudin18.2 targeted T cell-based immunotherapy in GC.

KRAS gene status in gastric signet-ring cell carcinoma patients and acts as biomarker of MEK inhibitor.

BACKGROUND: Signet-ring cell carcinoma (SRCC) is a specific subtype of stomach cancer with unique epidemiology. Here, we sought to explore the role of KRAS in SRCC. METHODS: KRAS status was studied both in The Cancer Genome Atlas (TCGA) and internal cohorts. Immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) were performed in formalin-fixed and paraffin-embedded (FFPE) samples. We explored patients' survival and clinicopathological characteristics in terms of KRAS mutation and expression. We also explored KRAS status and drug response curve of MEK/mTOR inhibitors in SRCC cell lines. RESULTS: Patients with KRAS mutations and copy number variation (CNV) showed higher mRNA level compared to non-mutant cases (P=0.003 and P<0.001). In internal cohort, 15 samples harbored KRAS mutations. Survival analysis showed that these patients had significantly lower overall survival (OS) (P=0.048). We further analyzed 75 patients with sufficient FFPE samples. Eight patients showed KRAS mutations and one patient showed KRAS amplification. The median OS was 12.5 months for patients with KRAS mutation, and 19.5 months for patients without KRAS mutation (P=0.005). Positive expression of KRAS as shown by IHC was detected in majority of SRCC samples, which was higher than our intestinal cohort (28% vs. 12.6%, P=0.033). We further explored the correlation between KRAS status and drug sensitivity in 4 SRCC cell lines. SNU601 and SNU668, which harbored KRAS mutation, were hypersensitive to MEK and mTOR inhibitors than KRAS wide type cell lines KATO-III and NUGC-4. CONCLUSIONS: Our findings demonstrate that KRAS gene plays an important role in SRCC and reveals therapeutic potential of targeting tumors by inhibiting MEK and mTOR pathways.

Individualized prediction of survival benefits from perioperative chemoradiotherapy for patients with resectable gastric cancer.

BACKGROUND: The survival benefits of perioperative chemoradiotherapy (PCRT) and perioperative chemotherapy (PCT) for resectable gastric cancer (GC) patients remain unclear. This study aimed to compare the effects of PCRT and PCT in patients with resectable GC and develop a nomogram to evaluate the prognosis and disease risk of patients. METHODS: A total of 6890 patients with stage IB-IIIC GC from 2010 to 2015 were retrieved from the Surveillance, Epidemiology and End Results (SEER) database. Univariate Cox proportional hazards regression analyses were performed to evaluate the prognostic value of involved variables. A new nomogram was constructed based on development cohort and validated by an external validation cohort. The clinical practicability and accuracy were assessed by concordance index (C-index), calibration plot, and receiver operating characteristic (ROC) curve. RESULTS: A better prognosis was obtained for patients with stage III GC treated with PCRT compared with those treated with PCT. Additionally, patients with grade III/IV, diffuse type GC, distal gastric cancer (DGC), tumor size >34 millimeters, or positive lymph nodes were more likely to benefit from PCRT. Multivariate analyses indicated that age, grade, tumor size, T stage, N stage, and comprehensive treatment were independent covariates. Excellent agreement of calibration plots and good discrimination power were obtained using the nomogram. The nomogram achieved a better net benefit than the 8th edition AJCC TNM staging. An online version was built based on the nomogram for convenient clinical use. CONCLUSION: The application of perioperative chemoradiotherapy should be determined according to the clinicopathological features of patients. Our nomogram provided a reliable tool for screening patients who were right for PCRT and evaluating individual survival benefits.

Highly expressed Claudin18.2 as a potential therapeutic target in advanced gastric signet-ring cell carcinoma (SRCC).

BACKGROUND: Advanced gastric signet-ring cell carcinoma (SRCC) is a specific type of malignant gastric cancer (GC) with distinct poorer survival. Claudin18.2 (CLDN18.2) is a promising neo-biomarker for the treatment of GC. Clinical trials of CLDN18.2-targeted antibody and T cell-based immunotherapy providing promising prospects for the treatment of GC. The effect of antibody therapy depended on the expression rate of CLDN18.2 has been found in clinical trials. This study aimed to determine the prevalence and the therapeutic value of CLDN18.2 in advanced gastric SRCC. METHODS: Expression of CLDN18.2 in 105 formalin-fixed, paraffin-embedded (FFPE) tumor tissues was detected by immunohistochemistry (IHC) and evaluated according to FAST criteria. Next-generation sequencing (NGS) using 416 pan-cancer genes panel was performed to characterize the genomic landscape in 61 advanced gastric SRCC patients. Fisher's exact test was used to determine gene differences in different CLDN18.2 expression levels. RESULTS: A total number of 105 advanced gastric SRCC samples were analyzed, of which 95.2% (100/105) were positive stained. Moderate-to-strong CLDN18.2 expression was observed in 64.8% (68/105) of all samples. In particularly, 21.0% (22/105) samples had positive staining in more than 90% tumor cells. No significance was found between CLDN18.2 expression and overall survival (OS). NGS results showed that single nucleotide variations (SNVs) could be frequently found in TP53 (26.2%), CDH1 (19.7%), MED12 (18.0%), PKHD1 (18.0%) and ARID1A (11.5%), besides, copy number variations (CNVs) were rich in NOTCH1 (18.0%) and FLT4 (9.8%) in SRCC samples. Moreover, SNVs in GRIN2A was found in 20% of the patients who had CLDN18.2 staining in <40% of tumor cells (P=0.043), indicating CLDN18.2 expression might be related to the aberration of GRIN2A in advanced gastric SRCC. CONCLUSIONS: The highly expressed CLDN18.2 among advanced gastric SRCC patients that we found certified the value of CLDN18.2-targeted therapy in this specific type of GC. In addition, Analyses between CLDN18.2 expression and genetic abnormalities provided novel therapeutic options for advanced gastric SRCC.

High BIM mRNA levels are associated with longer survival in advanced gastric cancer.

Chemotherapy drugs, including 5-fluorouracil (5-FU), oxaliplatin and docetaxel, are commonly used in the treatment of gastric cancer (GC). Apoptosis-relevant genes may be associated with drug resistance. In the present study, the messenger RNA (mRNA) expression levels of B-cell lymphoma 2 interacting mediator of cell death (BIM), astrocyte elevated gene-1 (AEG-1) and AXL receptor tyrosine kinase (AXL) were investigated in 131 advanced GC samples, and the expression levels of these genes were correlated with patients' overall survival (OS). All 131 patients received first-line FOLFOX combination chemotherapy with folinic acid and 5-FU, in which 56 patients were further treated with second-line docetaxel-based chemotherapy. A correlation between the mRNA expression levels of BIM and AEG-1 was observed (rs=0.30; P=0.002). There was no association between the mRNA expression levels of any of the individual genes analyzed and OS in patients only receiving first-line FOLFOX chemotherapy. In a subgroup of patients receiving docetaxel-based second-line chemotherapy, those with high or intermediate levels of BIM exhibited a median OS of 18.2 months [95% confidence interval (CI), 12.8-23.6], compared with 9.6 months (95% CI, 8.9-10.3) in patients with low BIM levels (P=0.008). However, there was no correlation between the mRNA expression levels of AEG-1 or AXL and OS. The risk of mortality was higher in patients with low BIM mRNA levels than in those with high or intermediate BIM mRNA levels (hazard ratio, 2.61; 95% CI, 1.21-5.62; P=0.010). Therefore, BIM may be considered as a biomarker to identify whether patients could benefit from docetaxel-based second-line chemotherapy in GC.

Regional but fatal: Intraperitoneal metastasis in gastric cancer.

Peritoneal carcinomatosis appears to be the most common pattern of metastasis or recurrence and is associated with poor prognosis in gastric cancer patients. Many efforts have been made to improve the survival in patients with peritoneal metastasis. Hyperthermic intraperitoneal chemotherapy remains a widely accepted strategy in the treatment of peritoneal dissemination. Several phase II-III studies confirmed that the combined cytoreducitve surgery and hyperthermic intraperitoneal chemotherapy resulted in longer survival in patients with peritoneal carcinomatosis. In addition, proper selection and effective regional treatment in patients with high risk of peritoneal recurrence after resection will further improve prognosis in local advanced gastric cancer patients.