Tumor microenvironment immune types in gastric cancer are associated with mismatch repair however, not HER2 status

Association between Helicobacter pylori infection, mismatch repair, HER2 and tumor-infiltrating lymphocytes in gastric cancer

BACKGROUND

The influence of Helicobacter-pylori (H. pylori) infection and the characteristics of gastric cancer (GC) on tumor-infiltrating lymphocyte (TIL) levels has not been extensively studied. Analysis of infiltrating-immune-cell subtypes as well as survival is necessary to obtain comprehensive information.

AIM

To determine the rates of deficient mismatch-repair (dMMR), HER2-status and H. pylori infection and their association with TIL levels in GC.

METHODS

Samples from 503 resected GC tumors were included and TIL levels were evaluated following the international-TILs-working-group recommendations with assessment of the intratumoral (IT), stromal (ST) and invasive-border (IB) compartments. The density of CD3, CD8 and CD163 immune cells, and dMMR and HER2-status were determined by immunohistochemistry (IHC). H. pylori infection was evaluated by routine histology and quantitative PCR (qPCR) in a subset of samples.

RESULTS

dMMR was found in 34.4%, HER2+ in 5% and H. pylori-positive in 55.7% of samples. High IT-TIL was associated with grade-3 (P = 0.038), while ST-TIL with grade-1 (P < 0.001), intestinal-histology (P < 0.001) and no-recurrence (P = 0.003). dMMR was associated with high TIL levels in the ST (P = 0.019) and IB (P = 0.01) compartments, and ST-CD3 (P = 0.049) and ST-CD8 (P = 0.05) densities. HER2- was associated with high IT-CD8 (P = 0.009). H. pylori-negative was associated with high IT-TIL levels (P = 0.009) when assessed by routine-histology, and with high TIL levels in the 3 compartments (P = 0.002-0.047) and CD8 density in the IT and ST compartments (P = 0.001) when assessed by qPCR. A longer overall survival was associated with low IT-CD163 (P = 0.003) and CD8/CD3 (P = 0.001 in IT and P = 0.002 in ST) and high IT-CD3 (P = 0.021), ST-CD3 (P = 0.003) and CD3/CD163 (P = 0.002).

CONCLUSION

TIL levels were related to dMMR and H. pylori-negativity. Low CD8/CD3 and high CD163/CD3 were associated with lower recurrence and longer survival.

Association between Helicobacter pylori infection, mismatch repair, HER2 and tumor-infiltrating lymphocytes in gastric cancer

BACKGROUND

The influence of Helicobacter-pylori (H. pylori) infection and the characteristics of gastric cancer (GC) on tumor-infiltrating lymphocyte (TIL) levels has not been extensively studied. Analysis of infiltrating-immune-cell subtypes as well as survival is necessary to obtain comprehensive information.

AIM

To determine the rates of deficient mismatch-repair (dMMR), HER2-status and H. pylori infection and their association with TIL levels in GC.

METHODS

Samples from 503 resected GC tumors were included and TIL levels were evaluated following the international-TILs-working-group recommendations with assessment of the intratumoral (IT), stromal (ST) and invasive-border (IB) compartments. The density of CD3, CD8 and CD163 immune cells, and dMMR and HER2-status were determined by immunohistochemistry (IHC). H. pylori infection was evaluated by routine histology and quantitative PCR (qPCR) in a subset of samples.

RESULTS

dMMR was found in 34.4%, HER2+ in 5% and H. pylori-positive in 55.7% of samples. High IT-TIL was associated with grade-3 (P = 0.038), while ST-TIL with grade-1 (P < 0.001), intestinal-histology (P < 0.001) and no-recurrence (P = 0.003). dMMR was associated with high TIL levels in the ST (P = 0.019) and IB (P = 0.01) compartments, and ST-CD3 (P = 0.049) and ST-CD8 (P = 0.05) densities. HER2- was associated with high IT-CD8 (P = 0.009). H. pylori-negative was associated with high IT-TIL levels (P = 0.009) when assessed by routine-histology, and with high TIL levels in the 3 compartments (P = 0.002-0.047) and CD8 density in the IT and ST compartments (P = 0.001) when assessed by qPCR. A longer overall survival was associated with low IT-CD163 (P = 0.003) and CD8/CD3 (P = 0.001 in IT and P = 0.002 in ST) and high IT-CD3 (P = 0.021), ST-CD3 (P = 0.003) and CD3/CD163 (P = 0.002).

CONCLUSION

TIL levels were related to dMMR and H. pylori-negativity. Low CD8/CD3 and high CD163/CD3 were associated with lower recurrence and longer survival.

Down-regulation of stimulator of interferon genes (STING) expression and CD8+ T-cell infiltration depending on HER2 heterogeneity in HER2-positive gastric cancer

BACKGROUND

HER2 signaling might be involved in the regulation of immune cell activation in the tumor microenvironment (TME) of gastric cancer (GC). However, the relationship between HER2 status and immune cell condition in the HER2-positive GC TME is not clearly understood.

METHODS

To investigate the effect of HER2 signaling on the activation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, which contributes to immune cell activation in the GC TME, we evaluated the associations among the expressions of HER2, cGAS-STING, and the number of CD8+ tumor-infiltrating lymphocytes (TIL) by considering HER2 heterogeneity in HER2-positive GC tissues. We also examined the effect of HER2 signaling on the activation of STING signaling in vitro using human HER2-positive GC cell lines.

RESULTS

The expression of HER2 is highly heterogeneous in HER2-positive GC tissues, and we found that the number of CD8+ TIL in HER2 high areas was significantly lower than that in HER2 low areas in HER2-positive GC tissues. Intriguingly, the tumor cell-intrinsic expression of STING, but not cGAS, was also significantly lower in the HER2 high areas than the HER2 low areas in HER2-positive GC tissues. Moreover, in vitro experiments, we demonstrated that the blockade of HER2 signaling increased the expression of STING and its target genes, including IFNB1, CXCL9/10/11, and CCL5, in HER2-positive GC cell lines.

CONCLUSIONS

Our results suggest that HER2 signaling might suppress immune cell activation in the GC TME by inhibiting STING signaling in tumor cells in HER2-positive GC.

Interspatial Distribution of Tumor and Immune Cells in Correlation with PD-L1 in Molecular Subtypes of Gastric Cancers

(1) Background: EBV-positive and mismatch repair-deficient (MMRd) gastric cancers (GCs) show higher levels of tumor-infiltrating lymphocytes (TILs) and PD-L1 expression and thus a more profound response to immunotherapy. However, the majority of GCs are EBV-negative (EBV−) and MMR proficient (MMRp). We analyzed PD-L1 expression and TILs in EBV-MMRpGCs in comparison to EBV-positive (EBV+) and MMRdGCs to identify an immunogenic phenotype susceptible to immunotherapy. (2) Methods: A next-generation tissue microarray of 409 primary resected GCs was analyzed by Epstein-Barr encoding region (EBER) in situ hybridization for MSH1, PMS2, MSH2, MSH6, PD-L1, and CD8 immunohistochemistry. PD-L1 positivity was defined as a combined positive score (CPS) of ≥1. CD8+ TILs and their proximity to cancer cells were digitally analyzed on the HALO™ image analysis platform. (3) Results: Eleven cases were EBV+, 49 cases MMRd, and 349 cases EBV-MMRpGCs. The highest rate of PD-L1 positivity was seen in EBV+GCs, followed by MMRdGCs and EBV-MMRpGCs (81.8%, 73.5%, and 27.8%, respectively). EBV+ and MMRdGCs also demonstrated increased numbers and proximity of CD8+ TILs to tumor cells compared to EBV-MMRpGCs (p < 0.001 each). PD-L1 status positively correlated with the total numbers of CD8+ TILs and their proximity to tumor cells in all subtypes, including EBV-MMRpGCs (p < 0.001 each). A total of 28.4% of EBV-MMRpGCs showed high CD8+ TILs independent of PD-L1. (4) Conclusions: PD-L1 and CD8 immunohistochemistry, supplemented by digital image analysis, may identify EBV-MMRpGCs with high immunoreactivity indices, indicating susceptibility to immunotherapy.

PD-L1 expression in EBV associated gastric cancer: a systematic review and meta-analysis

OBJECTIVES

The aim of this systematic review and meta-analysis is to the summarize the evidence on programmed cell death protein ligand 1 (PD-L1) in Epstein-Barr virus associated gastric cancer (EBVaGC) and to estimate the expression rate of PD-L1 among this subtype of Gastric Cancer (GC).

MATERIALS AND METHODS

For this study, PubMed^®, EMBASE^® and Web of Science^® databases were searched for articles published until 1st November 2021. A total of 43 eligible publications with a total of 11,327 patients were included analysis based on inclusion and exclusion criteria. A total of 41 publications present data for proportion estimation and 33 for comparison of PD-L1 between EBV positive and negative GC. DerSimonian-Laird random-effects model was used for meta-analysis.

RESULTS

The analysis showed that in EBVaGC the pooled positivity rate for PD-L1 was 54.6% (p < 0.001), with a high heterogeneity between the included studies, which was associated with variation on positivity criteria for PD-L1 expression. Overall, the study reveals an increased association between PD-L1 and EBVaGC (OR = 6.36, 95% CI 3.91-10.3, p < 0.001). Furthermore, the study revealed that GC with lymphoid stroma (GCLS) is highly associated with EBV (OR = 17.4, 95% CI 6.83-44.1, p < 0.001), with a pooled EBV positivity rate of 52.9% (p < 0.001).

CONCLUSIONS

Patients with EBVaGC tend to show higher PD-L1 expression, which enhances EBV positivity as a promising marker for patient selection for immunotherapy targeted agents. A uniform criteria for PD-L1 positivity in tumor cells is needed, as well as further prospective studies to validate our findings and their prognostic significance.

Clinicopathological Significance of EBV-Infected Gastric Carcinomas: A Meta-Analysis

Background and objectives: The present study aims to elucidate the clinicopathologic significance of Epstein-Barr virus (EBV) infection in gastric carcinomas (GCs) through a meta-analysis. Materials and Methods: Sixty-one eligible studies were included in the present meta-analysis. The included patients, with and without EBV infection, were 2063 and 17,684, respectively. We investigated the clinicopathologic characteristics and various biomarkers, including programmed death-ligand 1 (PD-L1) expression and tumor-infiltrating lymphocytes (TILs). Results: The estimated EBV-infected rate of GCs was 0.113 (95% confidence interval (CI): 0.088-0.143). The EBV infection rates in GC cells were 0.138 (95% CI: 0.096-0.194), 0.103 (95% CI: 0.077-0.137), 0.080 (95% CI: 0.061-0.106), and 0.042 (95% CI: 0.016-0.106) in the population of Asia, America, Europe, and Africa, respectively. There was a significant difference between EBV-infected and noninfected GCs in the male: female ratio, but not other clinicopathological characteristics. EBV infection rates were higher in GC with lymphoid stroma (0.573, 95% CI: 0.428-0.706) than other histologic types of GCs. There were significant differences in high AT-rich interactive domain-containing protein 1A (ARID1A) and PD-L1 expressions, and high CD8+ TILs between EBV-infected and noninfected GCs. Conclusions: Our results showed that EBV infection of GCs was frequently found in male patients and GCs with lymphoid stroma. EBV infection was significantly correlated with ARID1A and PD-L1 expressions and CD8+ TILs in GCs.

Global updates in the treatment of gastric cancer: a systematic review. Part 1: staging, classification and surgical treatment

Gastric cancer (GC) is the fifth malignancy and the third cause of cancer death worldwide, according to the global cancer statistics presented in 2018. Its definition and staging have been revised in the eight edition of the AJCC/TNM classification, which took effect in 2018. Novel molecular classifications for GC have been recently established and the process of translating these classifications into clinical practice is ongoing. The cornerstone of GC treatment is surgical, in a context of multimodal therapy. Surgical treatment is being standardized, and is evolving according to new anatomical concepts and to the recent technological developments. This is leading to a massive improvement in the use of mini-invasive techniques. Mini-invasive techniques aim to be equivalent to open surgery from an oncologic point of view, with better short-term outcomes. The persecution of better short-term outcomes also includes the optimization of the perioperative management, which is being implemented on large scale according to the enhanced recovery after surgery principles. In the era of precision medicine, multimodal treatment is also evolving. The long-time-awaited results of many trials investigating the role for preoperative and postoperative management have been published, changing the clinical practice. Novel investigations focused both on traditional chemotherapeutic regimens and targeted therapies are currently ongoing. Modern platforms increase the possibility for further standardization of the different treatments, promote the use of big data, and open new possibilities for surgical learning. This systematic review in two parts assesses all the current updates in GC treatment.