HER2-positive gastric cancer with concomitant MET and/or EGFR overexpression: a distinct subset of patients for dual inhibition therapy

Ferroptosis regulating lipid peroxidation metabolism in the occurrence and development of gastric cancer

BACKGROUND

Gastric cancer is one of the most common malignant tumors in the world, and its occurrence and development involve complex biological processes. Iron death, as a new cell death mode, has attracted wide attention in recent years. However, the regulatory mechanism of iron death in gastric cancer and its effect on lipid peroxidation metabolism remain unclear.

AIM

To explore the role of iron death in the development of gastric cancer, reveal its relationship with lipid peroxidation, and provide a new theoretical basis for revealing the molecular mechanism of the occurrence and development of gastric cancer.

METHODS

The process of iron death in gastric cancer cells was simulated by cell culture model, and the occurrence of iron death was detected by fluorescence microscopy and flow cytometry. The changes of gene expression related to iron death and lipid peroxidation metabolism were analyzed by high-throughput sequencing technology. In addition, a mouse model of gastric cancer was established, and the role of iron death in vivo was studied by histology and immunohistochemistry, and the level of lipid peroxidation was detected. These methods comprehensively and deeply reveal the regulatory mechanism of iron death on lipid peroxidation metabolism in the occurrence and development of gastric cancer.

RESULTS

Iron death was significantly activated in gastric cancer cells, and at the same time, associated lipid peroxidation levels increased significantly. Through high-throughput sequencing analysis, it was found that iron death regulated the expression of several genes related to lipid metabolism. In vivo experiments demonstrated that increased iron death in gastric cancer mice was accompanied by a significant increase in lipid peroxidation.

CONCLUSION

This study confirmed the important role of iron death in regulating lipid peroxidation metabolism in the occurrence and development of gastric cancer. The activation of iron death significantly increased lipid peroxidation levels, revealing its regulatory mechanism inside the cell.

HER2-Positive Gastric Cancer and Antibody Treatment: State of the Art and Future Developments

Despite a decreasing incidence in Western countries, gastric cancer is among the most common cancer subtypes globally and is associated with one of the highest tumor-related mortality rates. Biomarkers play an increasing role in the treatment against gastric cancer. HER2 was one of the first biomarkers that found its way into clinical practice. Since the ToGA trial, trastuzumab has been part of first-line palliative chemotherapy in metastatic or unresectable gastric cancer. HER2-targeting agents, such as the tyrosine kinase inhibitor lapatinib, the antibody drug conjugate (ADC) trastuzumab-emtansine or dual HER2 inhibition (pertuzumab and trastuzumab), have been investigated in the second-line setting but led to negative study results. More recently, the ADC trastuzumab-deruxtecan was authorized after the failure of trastuzumab-based treatment. However, further improvements in HER2-directed therapy are required as resistance mechanisms and HER2 heterogeneity limit the existing treatment options. This review aims to give an overview of the current standard-of-care HER2-directed therapy in gastric cancer, as well as its challenges and future developments.

New clinical trial design in precision medicine: discovery, development and direction

In the era of precision medicine, it has been increasingly recognized that individuals with a certain disease are complex and different from each other. Due to the underestimation of the significant heterogeneity across participants in traditional "one-size-fits-all" trials, patient-centered trials that could provide optimal therapy customization to individuals with specific biomarkers were developed including the basket, umbrella, and platform trial designs under the master protocol framework. In recent years, the successive FDA approval of indications based on biomarker-guided master protocol designs has demonstrated that these new clinical trials are ushering in tremendous opportunities. Despite the rapid increase in the number of basket, umbrella, and platform trials, the current clinical and research understanding of these new trial designs, as compared with traditional trial designs, remains limited. The majority of the research focuses on methodologies, and there is a lack of in-depth insight concerning the underlying biological logic of these new clinical trial designs. Therefore, we provide this comprehensive review of the discovery and development of basket, umbrella, and platform trials and their underlying logic from the perspective of precision medicine. Meanwhile, we discuss future directions on the potential development of these new clinical design in view of the "Precision Pro", "Dynamic Precision", and "Intelligent Precision". This review would assist trial-related researchers to enhance the innovation and feasibility of clinical trial designs by expounding the underlying logic, which be essential to accelerate the progression of precision medicine.

Site-specific protein biomarkers in gastric cancer: a comprehensive review of novel biomarkers and clinical applications

INTRODUCTION

Gastric cancer (GC) is the fifth most common cancer and the fourth leading cause of cancer-related death worldwide, thus representing a significant global health burden. Early detection and monitoring of GC are essential to improve patient outcomes. While traditional cancer biomarkers such as carcinoembryonic antigen, carbohydrate antigen (CA) 19-9, and CA 72-4 are widely used, their limited sensitivity and specificity necessitate the exploration of alternative biomarkers.

AREAS COVERED

This review comprehensively analyzes the landscape of GC protein biomarkers identified from 2019 to 2022, with a focus on tissue, blood, urine, saliva, gastric juice, ascites, and exhaled breath as sample sources. We address the potential clinical applications of these biomarkers in early diagnosis, monitoring recurrence, and predicting survival and therapeutic response of GC patients.

EXPERT OPINION

The discovery of novel protein biomarkers holds great promise for improving the clinical management of GC. However, further validation in large, diverse cohorts is needed to establish the clinical utility of these biomarkers. Integrating these biomarkers with existing diagnostic and monitoring approaches will likely lead to improved personalized treatment plans and patient outcomes.

Significance of tumor heterogeneity of p-Smad2 and c-Met in HER2-positive gastric carcinoma with lymph node metastasis

Background

Tumor heterogeneity has frequently been observed in gastric cancer (GC), but the correlation between patients’ clinico-pathologic features and the tumoral heterogeneity of GC-associated molecules is unclear. We investigated the correlation between lymph node metastasis and the intra-tumoral heterogeneity of driver molecules in GC.

Materials and methods

We retrospectively analyzed the cases of 504 patients who underwent a gastrectomy at the Department of Gastroenterological Surgery, Osaka Metropolitan University and 389 cases drawn from The Cancer Genome Atlas (TCGA) data. We performed a clustering analysis based on eight cancer-associated molecules including HER2, c-Met, and p-Smad2 using the protein expression revealed by our immunohistochemical study of the patients’ and TCGA cases. We determined the correlations between HER2 expression and the other molecules based on the degree of lymph node metastasis.

Results

Immunohistochemical staining data showed that a 43 of the 504 patients with GC (8.5%) were HER2-positive. In the HER2-positive cases, the expressions of c-Met and p-Smad2 were increased in accord with the lymph-node metastatic level. The overall survival of the HER2-positive GC patients with both p-Smad2 and c-Met expression was significantly (p = 0.030) poorer than that of the patients with p-Smad2-negative and/or c-Met-negative expression. The results of the TCGA data analysis revealed that 58 of the 389 GC cases (14.9%) were ERBB2-positive. MET expression was more frequent in the N1 metastasis group than the N0 group. In the high lymph-node metastasis (N2 and N3) group, SMAD2 expression was more frequent, as was ERBB2 and MET expression.

Conclusion

p-Smad2 and c-Met signaling might play important roles in lymph node metastasis in HER2-positive GC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09681-3.

The Significance of MET Expression and Strategies of Targeting MET Treatment in Advanced Gastric Cancer

Background

Accurate assessment of predictive biomarker expression is critical in patient selection in clinical trials or clinical practice. However, changes in biomarker expression may occur after treatment. The aim of the present study was to evaluate the effects of chemotherapy on MET expression in gastric cancer (GC).

Methods

MET expression was examined immunohistochemically before and after treatment in 122 patients with unresectable or recurrent GC, and was evaluated according to H-score or the scoring criteria used in the MetMAb trial. MET gene amplification was assessed by chromogenic in situ hybridization (CISH). The antitumor effect of MET targeted therapy was investigated in human gastric cancer cells in vitro and in vivo, and the underlying molecular mechanisms were analyzed by western blot.

Results

MET expression was associated with Lauren classification as well as tumor differentiation by either scoring system. MET amplification was not associated with clinical characteristics. Of the 71 patients who had paired pre- and post-treatment tumor tissues, 28 patients (39%) were initially positive for MET expression, and 43 (61%) were negative. Twenty-five patients (35%) showed significant changes in MET expression after treatment (P=0.007). Additionally, there was a concomitant overexpression of MET and HER2 in a subset of GC patients. MET inhibitor volitinib could significantly inhibit cell proliferation and xenograft growth in vitro and in vivo in MKN45 cells with MET and phosphorylated MET (pMET) high expressions via suppressing downstream PI3K/Akt and MAPK signaling pathways. Furthermore, combination therapy targeting both MET and HER2 demonstrated a synergistic antitumor activity.

Conclusions

MET expression is altered post chemotherapy and MET status should be evaluated in real-time. Both MET and pMET expressions might need to be considered for patients suitable for volitinib treatment.

[Intratumoral heterogeneity of gastric cancer-impact on biomarker evaluation]

BACKGROUND

Gastric carcinomas often measure more than 5 cm at primary diagnosis. Predictive biomarker testing is usually carried out on tissue biopsies, which do not represent the entire tumor biology and intratumoral heterogeneity.

OBJECTIVES

The aim of this study was to explore gastric cancer's intratumoral heterogeneity and its impact on the evaluation of predictive and prognostic biomarkers.

MATERIALS AND METHODS

The study cohort consisted of approximately 500 patients with therapy-naive adenocarcinomas of the stomach or the esophagogastric junction. The following biomarkers were determined: HER2, MET, Ki67, PD-L1/PD‑1, VISTA, EBV-status, and PIK3CA.

RESULTS

All examined biomarkers were influenced by gastric cancer's intratumoral heterogeneity. Tissue biopsies might carry the risk of sampling errors, which may significantly hamper adequate tumor classification in a clinical setting.

CONCLUSIONS

Our findings unravel issues of tumor heterogeneity in gastric cancer. Biomarker diagnostics on tissue biopsies should be carried out on at least five biopsies of different tumor areas. If possible, biomarker diagnostics should be repeated on resection specimens. Tissue microarrays should no longer be used for research studies of gastric cancer.

From Interconnection between Genes and Microenvironment to Novel Immunotherapeutic Approaches in Upper Gastro-Intestinal Cancers-A Multidisciplinary Perspective

Despite the progress during the last decade, patients with advanced gastric and esophageal cancers still have poor prognosis. Finding optimal therapeutic strategies represents an unmet need in this field. Several prognostic and predictive factors have been evaluated and may guide clinicians in choosing a tailored treatment. Data from large studies investigating the role of immunotherapy in gastrointestinal cancers are promising but further investigations are necessary to better select those patients who can mostly benefit from these novel therapies. This review will focus on the treatment of metastatic esophageal and gastric cancer. We will review the standard of care and the role of novel therapies such as immunotherapies and CAR-T. Moreover, we will focus on the analysis of potential predictive biomarkers such as Modify as: Microsatellite Instability (MSI) and PD-L1, which may lead to treatment personalization and improved treatment outcomes. A multidisciplinary point of view is mandatory to generate an integrated approach to properly exploit these novel antiproliferative agents.

Towards precision oncology for HER2 blockade in gastroesophageal adenocarcinoma

Gastroesophageal adenocarcinoma (GEA) represents a very heterogeneous disease and patients in advanced stages have a very poor prognosis. Although several molecular classifications have been proposed, precision medicine for HER2-amplified GEA patients still represents a challenge. Despite improvement in clinical outcomes obtained by adding trastuzumab to first-line platinum-based chemotherapy, no other anti-HER2 agents used first-line or beyond progression have demonstrated any benefit. Several factors contribute to this failure. Among them, variable HER2 amplification assessment, tumour heterogeneity, molecular mechanisms of resistance and microenvironmental factors could limit the effectiveness of anti-HER2 blockade. Identifying the factors responsible for both primary and acquired resistance is a priority for providing an improved, personalised approach. In this review, we examine current treatments for HER2-amplified GEA, their potential mechanisms of resistance and the ways to overcome them, investigating the most relevant translational studies with anti-HER2 agents in GEA, as well as novel agents under development in this field.

Tumor Genomic Profiling Guides Patients with Metastatic Gastric Cancer to Targeted Treatment: The VIKTORY Umbrella Trial

The VIKTORY (targeted agent eValuation In gastric cancer basket KORea) trial was designed to classify patients with metastatic gastric cancer based on clinical sequencing and focused on eight different biomarker groups (RAS aberration, TP53 mutation, PIK3CA mutation/amplification, MET amplification, MET overexpression, all negative, TSC2 deficient, or RICTOR amplification) to assign patients to one of the 10 associated clinical trials in second-line (2L) treatment. Capivasertib (AKT inhibitor), savolitinib (MET inhibitor), selumetinib (MEK inhibitor), adavosertib (WEE1 inhibitor), and vistusertib (TORC inhibitor) were tested with or without chemotherapy. Seven hundred seventy-two patients with gastric cancer were enrolled, and sequencing was successfully achieved in 715 patients (92.6%). When molecular screening was linked to seamless immediate access to parallel matched trials, 14.7% of patients received biomarker-assigned drug treatment. The biomarker-assigned treatment cohort had encouraging response rates and survival when compared with conventional 2L chemotherapy. Circulating tumor (ctDNA) analysis demonstrated good correlation between high MET copy number by ctDNA and response to savolitinib. SIGNIFICANCE: Prospective clinical sequencing revealed that baseline heterogeneity between tumor samples from different patients affected response to biomarker-selected therapies. VIKTORY is the first and largest platform study in gastric cancer and supports both the feasibility of tumor profiling and its clinical utility.This article is highlighted in the In This Issue feature, p. 1325.

Bridging genomics and phenomics of gastric carcinoma

Genetic alterations are the starting point leading to numerous changes in clinical and pathologic features (phenotypes) of individual cancers; however, their inter-relationships in gastric cancers (GC) are unclear. We performed massive parallel sequencing of 381 cancer-related genes and compared the results with clinical and pathologic findings in 330 GC. High tumor mutation burden (TMB) accounted for 11% of GC (n = 37) and all 19 MSI-H GCs were high TMB. High TMB was significantly more frequent in intestinal-type by Lauren, tumor with higher host cellular immune response, earlier AJCC stage and favorable prognosis. The most significantly mutated genes were TP53 (54%), ARID1A (23%), CDH1 (22%), PIK3CA (12%), RNF43 (10%) and KRAS (9%). For receptor tyrosine kinases, amplifications detected by immunohistochemistry were higher than sequencing (HER2, 9.1% vs. 5.8%; EGFR, 11.2% vs. 6.1%; FGFR2, 4.6% vs. 3.9%, c-MET, 3.4% vs. 0.9%). PTEN protein loss (22%) correlated well with underlying PTEN alterations while ATM loss (27%) was not significantly correlated with genetic alterations of ATM. p53 protein expression predicted alterations of TP53 with high sensitivity (97.8%) and low (15.9%) specificity. The poorly cohesive histology/CDH1-mutant GC subgroup showed the worst survival (p < 0.001). PD-L1 expression was significantly associated with MSI-H, MLH1 loss, ATM loss, MET positivity, higher host immune response, and genetic alterations of ARID1A, BRD3, PIK3CA, KRAS, MAP3K13, CDH2, PTEN and ESR1. The merged clinical, pathology and genomics of GC provide a better understanding of GC and new insights into the treatment of GC.

Combination of Docetaxel Plus Savolitinib in Refractory Cancer Patients: A Report on Phase I Trial

MET amplification is a frequently observed genomic aberration in solid tumors. We conducted a phase I trial to evaluate dose-limiting toxicity (DLT) and recommended phase II dose (RP2D) for the combination therapy. The following dose levels were tested in this single-arm phase I study: docetaxel as an intravenous infusion over 1 hour at 60 mg/m² once every 3 weeks of a 21-day schedule plus savolitinib (level 1, 200 mg qd; level 2, 400 mg qd; level 3, 600 mg qd; level 4800 mg qd). In total, there were 17 patients enrolled on to this study [7 gastric cancer (GC) patients, 5 melanoma patients, 3 sarcoma patients, and 2 rectal cancer patients]. Most of the patients (14 of 17) were heavily pretreated (≥third line or greater lines of treatment). For the first 3 cohorts (200 mg savolitinib + docetaxel 60 mg/m², 400 mg savolitinib + docetaxel 60 mg/m², 600 mg savolitinib + docetaxel 60 mg/m²), there were no DLTs. In the fourth dose cohort (800 mg savolitinib + docetaxel 60 mg/m²), one DLT occurred with generalized edema grade 3 that required intensive management. One GC patient with both MET overexpression (3+) and MET amplification (MET/CEP7 ratio, 7.3) achieved a durable partial response for 297 days, and another MET-amplified GC patient (MET/CEP7 ratio, 7.6) achieved stable disease for 86 days. Due to the higher incidence of G4 neutropenia in cohort 4 (800 mg), we recommend savolitinib 600 mg qd in combination with docetaxel 60 mg/m² as the RP2D for phase II trial. The combination therapy demonstrated a very promising antitumor activity with durable responses in MET amplified GC patients.

MET is overexpressed in microsatellite instability-high gastric carcinoma

BACKGROUND

MET is a tyrosine kinase receptor for the hepatocyte growth factor, and its overexpression is a poor prognostic factor in gastric carcinomas. Programmed death-ligand 1 (PD-L1) is an important biomarker of immunotherapy and is frequently positive in microsatellite instability-high (MSI-H) gastric carcinomas. In lung cancers, MET activation up-regulates PD-L1 expression. In this study, we investigated expression of MET and PD-L1 in MSI-H gastric carcinoma and the effects on prognosis.

METHODS

MET and PD-L1 (SP142) immunohistochemistry was performed in 73 gastric carcinomas with MSI-H. In cases with MET overexpression, we performed fluorescent in situ hybridization (FISH). PD-L1 expression was calculated from both tumor cells (2+ and 3+ in > 10% of tumor cells was defined as PD-L1^TC+) and immune cells (positive in >5% immune cells was PD-L1^IC+), and also used a combined positive score (CPS; number of PD-L1 staining cells relative to all viable tumor cells; > 1 was PD-L1⁺).

RESULTS

In 73 MSI-H gastric carcinomas, MET overexpression was observed in 11 cases (15.1%). In all 11 cases with MET overexpression,MET amplification was not found. MET overexpression was not related to any of clinico-pathological variables and PD-L1 expression. However, the PD-L1 CPS tended to be higher in tumors that were MET positive. Although MET overexpression alone was not a prognostic indicator, combined MET overexpression/PD-L1 predictive models showed that patients with MET⁺/PD-L1⁺ showed the best prognosis for overall survival as compared to other groups.

CONCLUSION

MET overexpression was observed in 15% of MSI-H gastric carcinomas and was associated with high level expression of PD-L1.

The association among HER2, MET and FOXP3 expression and tumor regression grading in gastric adenocarcinoma

Although the introduction of the perioperative chemotherapy on the management of gastric cancer has improved patients survival, heterogeneity of clinical outcomes has been evidenced in parallel to different histopathological regression pattern of gastric cancer cells. Thus, this study evaluated the tumor regression grading (TRG) in a series of post-treatment gastric tumors and its associations with HER2, MET, and FOXP3 expression. Material of 54 gastric cancer samples was available for TRG evaluation and immunohistochemistry. We found that total and subtotal pathologic response were significantly associated to the intestinal subtype (p = 0.04) and that well-differentiated tumors were significantly correlated with total or partial response (p = 0.019). Although not associated with the TRG, FOXP3 expression in gastric tumors was associated to poorly differentiated tumors (p = 0.03), to the diffuse and mixed subtypes together (p = 0.04) and to the presence of vascular infiltration (p = 0.04), while HER2 overexpression was associated to better differentiated cases (p = 0.04) and to the absence of vascular infiltration (p = 0.02). MET expression, however, showed no association with the analyzed clinicopathological factors. This study highlights the role of tissue differentiation on pathological response to neoadjuvant chemotherapy in gastric cancer and shows no impact between FOXP3, HER2 and MET expression in terms of TRG.

Genomic Profiling of HER2-Positive Gastric Cancer: PI3K/Akt/mTOR Pathway as Predictor of Outcomes in HER2-Positive Advanced Gastric Cancer Treated with Trastuzumab

BACKGROUND

HER2-positive gastric cancer (GC) affects 7%-34% of patients with GC. Trastuzumab-based first-line treatment has become the standard of care for HER2-positive advanced gastric cancer (AGC). However, there are no clinically validated biomarkers for resistance to HER2-targeted therapies. Upregulation of PI3K pathway and tyrosine kinase receptor (TKR) alterations have been noted as molecular mechanisms of resistance in breast cancer. Our study aimed to perform a molecular characterization of HER2-positive AGC and investigate the role of PI3K/Akt/mTOR signaling pathway activation and TKR gene copy number (GCN) gains as predictive biomarkers in HER2-positive AGC treated with trastuzumab.

PATIENTS AND METHODS

Forty-two HER2-positive GC samples from patients treated with trastuzumab-based first-line chemotherapy were selected. DNA samples were sequenced. PTEN and MET immunohistochemistry were also performed.

RESULTS

Concurrent genetic alterations were detected in 97.1% of HER2-positive AGC. We found activation of PI3K/Akt/mTOR pathway in 52.4% of patients and TKR GCN gains in 38.1%. TKR GCN gains did not correlate with overall survival (OS) or progression-free survival (PFS). Multivariate Cox models showed that PI3K/Akt/mTOR activation negatively affects the effectiveness of trastuzumab-based chemotherapy in terms of OS and PFS.

CONCLUSION

Our results provide for the first time a detailed molecular profile of concurrent genetic alterations in HER2-positive AGC. PI3K pathway activation could be used as a predictive marker of worse outcome in this patient population. In addition, gains in copy number of other TKR genes in this subgroup may also influence the survival benefit obtained with trastuzumab.

IMPLICATIONS FOR PRACTICE

This article reports, for the first time, a detailed molecular profile of genomic alterations in patients with HER2-positive advanced gastric cancer (AGC). PI3K/Akt/mTOR signaling pathway activation seems to have a differentially negative effect on overall survival and progression-free survival in AGC treated with trastuzumab-based chemotherapy. Combining different targeted agents could be a successful therapeutic strategy to improve the prognosis of HER2-positive AGC.

Receptor tyrosine kinase amplified gastric cancer: Clinicopathologic characteristics and proposed screening algorithm

Although targeted therapy for receptor tyrosine kinases (RTKs) of advanced gastric cancers (AGCs) has been in the spotlight, guidelines for the identification of RTK-amplified gastric cancers (RA-GCs) have not been established. In this study, we investigate clinicopathologic characteristics of RA-GCs and propose a screening algorithm for their identification. We performed immunohistochemistry (IHC) for MLH1, MSH2, PMS2, MSH6, key RTKs (EGFR, HER2, MET), and p53, in situ hybridization for Epstein-Barr virus encoding RNA, and silver in situ hybridization (SISH) for EGFR, HER2, and MET using tissue microarrays of 993 AGCs. On IHC, 157 (15.8%) 61, (6.15%), and 85 (8.56%) out of 993 cases scored 2+ or 3+ for EGFR, HER2, and MET, respectively. On SISH, 31.2% (49/157), 80.3% (49/61), and 30.6% (26/85) of 2+ or 3+ cases on IHC showed amplification of the corresponding genes. Of the 993 cases, 104 were classified as RA-GCs. RA-GC status correlated with older age (P < 0.001), differentiated histology (P = 0.001), intestinal or mixed type by Lauren classification (P < 0.001), lymphovascular invasion (P = 0.026), and mutant-pattern of p53 (P < 0.001). The cases were divided into four subgroups using two classification systems, putative molecular classification and histologic-molecular classification, based on Lauren classification, IHC, and SISH results. The histologic-molecular classification showed higher sensitivity for identification of RA-GCs and predicted patient prognosis better than the putative molecular classification. In conclusion, RA-GCs show unique clinicopathologic features. The proposed algorithm based on histologic-molecular classification can be applied to select candidates for genetic examination and targeted therapy.

MET overexpression, gene amplification and relevant clinicopathological features in gastric adenocarcinoma

This study was conducted to investigate the expression of MET in Chinese gastric adenocarcinoma cohort, the correlation between MET overexpression and clinical pathological features, HER2 expression and MET gene amplification. A total of 816 gastric adenocarcinoma patients were included and MET and HER2 immunohistochemical (IHC) staining were performed. IHC and dual-color silver in situ hybridization analysis were performed in the tissue microarrays, constructed from the 240 patients who were randomly selected. MET overexpression (IHC 3+) was observed in 6.0% (49/816) of the cohort. MET overexpression rate was higher in patients with poor prognostic factors, such as clinical stages III/IV (p =0.012) and pathologic stages T3/T4 (p =0.027). The HER2 overexpression (IHC 3+) rate was 8.8% (72/816) and MET overexpression rate was higher in HER2 positive patients (9.7%, 7/72). A high concordance rate (94.6%) between MET overexpression and gene amplification was demonstrated. Therefore, MET overexpression could serve as a prognostic biomarker and a potential therapeutic target for gastric cancer.

Biomarkers of Primary Resistance to Trastuzumab in HER2-Positive Metastatic Gastric Cancer Patients: the AMNESIA Case-Control Study

Purpose: Refining the selection of HER2-positive metastatic gastric cancer patient candidates for trastuzumab is a challenge of precision oncology. Preclinical studies have suggested several genomic mechanisms of primary resistance, leading to activation of tyrosine kinase receptors other than HER2 or downstream signaling pathways.Experimental Design: We carried out this multicenter, prospective, case-control study to demonstrate the negative predictive impact of a panel of candidate genomic alterations (AMNESIA panel), including EGFR/MET/KRAS/PI3K/PTEN mutations and EGFR/MET/KRAS amplifications. Hypothesizing a prevalence of candidate alterations of 30% and 0% in resistant and sensitive HER2-positive patients, respectively, 20 patients per group were needed.Results: AMNESIA panel alterations were significantly more frequent in resistant (11 of 20, 55%) as compared with sensitive (0% of 17) patients (P < 0.001), and in HER2 IHC 2⁺ (7 of 13, 53.8%) than 3⁺ (4 of 24, 16.7%) tumors (P = 0.028). Patients with tumors bearing no candidate alterations had a significantly longer median progression-free [5.2 vs. 2.6 months; HR, 0.34; 95% confidence interval (CI), 0.07-0.48; P = 0.001] and overall survival (16.1 vs. 7.6 months; HR, 0.38; 95% CI, 0.09-0.75; P = 0.015). The predictive accuracy of the AMNESIA panel and HER2 IHC was 76% and 65%, respectively. The predictive accuracy of the combined evaluation of the AMNESIA panel and HER2 IHC was 84%.Conclusions: Our panel of candidate genomic alterations may be clinically useful to predict primary resistance to trastuzumab in patients with HER2-positive metastatic gastric cancer and should be further validated with the aim of molecularly stratifying HER2-addicted cancers for the development of novel treatment strategies. Clin Cancer Res; 24(5); 1082-9. ©2017 AACR.

FOXO1 Suppression is a Determinant of Acquired Lapatinib-Resistance in HER2-Positive Gastric Cancer Cells Through MET Upregulation

Purpose

Lapatinib is a candidate drug for treatment of trastuzumab-resistant, human epidermal growth factor receptor 2 (HER2)–positive gastric cancer (GC). Unfortunately, lapatinib resistance renders this drug ineffective. The present study investigated the implication of forkhead box O1 (FOXO1) signaling in the acquired lapatinib resistance in HER2-positive GC cells.

Materials and Methods

Lapatinib-resistant GC cell lines (SNU-216 LR2-8) were generated in vitro by chronic exposure of lapatinib-sensitive, HER2-positive SNU-216 cells to lapatinib. SNU-216 LR cells with FOXO1 overexpression were generated by stable transfection of a constitutively active FOXO1 mutant (FOXO1A3). HER2 and MET in SNU-216 LR cells were downregulated using RNA interference. The sensitivity of GC cells to lapatinib and/or cisplatin was determined by crystal violet assay. In addition, Western blot analysis, luciferase reporter assay and reverse transcription–polymerase chain reaction were performed.

Results

SNU-216 LR cells showed upregulations of HER2 and MET, but downregulation of FOXO1 compared to parental SNU-216 cells. FOXO1 overexpression in SNU-216 LR cells significantly suppressed resistance to lapatinib and/or cisplatin. In addition, FOXO1 negatively controlled HER2 and MET at the transcriptional level and was negatively controlled by these molecules at the post-transcriptional level. A positive crosstalk was shown between HER2 and MET, each of which increased resistance to lapatinib and/or cisplatin.

Conclusion

FOXO1 serves as an important linker between HER2 and MET signaling pathways through negative crosstalks and is a key regulator of the acquired lapatinib resistance in HER2-positive GC cells. These findings provide a rationale for establishing a novel treatment strategy to overcome lapatinib resistance in a subtype of GC patients.

Clinicopathological Significance and Diagnostic Accuracy of c-MET Expression by Immunohistochemistry in Gastric Cancer: A Meta-Analysis

PURPOSE

The aim of the present study was to elucidate the clinicopathological significance and diagnostic accuracy of immunohistochemistry (IHC) for determining the mesenchymal epidermal transition (c-MET) expression in patients with gastric cancer (GC).

MATERIALS AND METHODS

The present meta-analysis investigated the correlation between c-MET expression as determined by IHC and the clinicopathological parameters in 8,395 GC patients from 37 studies that satisfied the eligibility criteria. In addition, a concordance analysis was performed between c-MET expression as determined by IHC and c-MET amplification, and the diagnostic test accuracy was reviewed.

RESULTS

The estimated rate of c-MET overexpression was 0.403 (95% confidence interval [CI], 0.327~0.484) and it was significantly correlated with male patients, poor differentiation, lymph node metastasis, higher TNM stage, and human epidermal growth factor receptor 2 (HER2) positivity in IHC analysis. There was a significant correlation between c-MET expression and worse overall survival rate (hazard ratio, 1.588; 95% CI, 1.266~1.992). The concordance rates between c-MET expression and c-MET amplification were 0.967 (95% CI, 0.916~0.987) and 0.270 (95% CI, 0.173~0.395) for cases with non-overexpressed and overexpressed c-MET, respectively. In the diagnostic test accuracy review, the pooled sensitivity and specificity were 0.56 (95% CI, 0.50~0.63) and 0.79 (95% CI, 0.77~0.81), respectively.

CONCLUSIONS

The c-MET overexpression as determined by IHC was significantly correlated with aggressive tumor behavior and positive IHC status for HER2 in patients with GC. In addition, the c-MET expression status could be useful in the screening of c-MET amplification in patients with GC.

Proton Pump Inhibition Enhances the Cytotoxicity of Paclitaxel in Cervical Cancer

Purpose

This study was conducted to investigate whether a proton pump inhibitor (PPI) could enhance chemosensitivity via the inhibition of vacuolar-type H⁺ ATPase (V-ATPase) in cervical cancer.

Materials and Methods

The expression of V-ATPase was evaluated in 351 formalin-fixed, paraffin-embedded human cervical cancer tissues using immunohistochemistry and compared with clinicopathologic risk factors for disease prognosis. The influence of cell proliferation and apoptosis following V-ATPase siRNA transfection or esomeprazole pretreatment was assessed in cervical cancer cell lines using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and enzyme-linked immunosorbent assay, respectively.

Results

Immunohistochemical analysis revealed that V-ATPase was expressed in about 60% of cervical cancer tissue samples (211/351), and the expression was predominantly found in adenocarcinoma histology (p=0.016). Among patients with initially bulky cervical cancer (n=89), those with V-ATPase expression had shorter disease-free survival (p=0.005) and overall survival (p=0.023). Co-treatment with V-ATPase siRNA or esomeprazole with paclitaxel significantly decreased the cell proliferation of cervical cancer cell lines, including HeLa and INT407, compared to cell lines treated with paclitaxel alone (p < 0.01). Moreover, V-ATPase siRNA or esomeprazole followed by paclitaxel significantly increased the expression of active caspase-3 in these cells compared to cells treated with paclitaxel alone (both, p < 0.05).

Conclusion

V-ATPase was predominantly expressed in cervical adenocarcinoma, and the expression of V-ATPases was associated with poor prognosis. The inhibition of V-ATPase via siRNA or PPI (esomeprazole) might enhance the chemosensitivity of paclitaxel in cervical cancer cells.

Gastrointestinal malignancies harbor actionable MET exon 14 deletions

Recently, MET exon 14 deletion (METex14del) has been postulated to be one potential mechanism for MET protein overexpression. We screened for the presence of METex14del transcript by multiplexed fusion transcript analysis using nCounter assay followed by confirmation with quantitative reverse transcription PCR with correlation to MET protein expression by immunohistochemistry (IHC) and MET amplification by fluorescence in situ hybridization (FISH). We extracted RNAs from 230 patients enrolled onto the prospective molecular profiling clinical trial (NEXT-1) (NCT02141152) between November 2013 and August 2014. Thirteen METex14del cases were identified including 3 gastric cancer, 4 colon cancer, 5 non-small cell lung cancer, and one adenocarcinoma of unknown primary. Of these 13 METex14del cases, 11 were MET IHC 3+ and 2 were 2+. Only one out of the 13 METex14del cases was MET amplified (MET/CEP ratio > 2.0). Growths of two (gastric, colon) METex14del+ patient tumor derived cell lines were profoundly inhibited by both MET tyrosine kinase inhibitors and a monoclonal antibody targeting MET. In conclusion, METex14del is a unique molecular aberration present in gastrointestinal (GI) malignancies corresponding with overexpression of MET protein but rarely with MET amplification. Substantial growth inhibition of METex14del+ patient tumor derived cell lines by several MET targeting drugs strongly suggests METex14del is a potential actionable driver mutation in GI malignancies.

Patient-derived cell models as preclinical tools for genome-directed targeted therapy

Background

In this study, we established patient-derived tumor cell (PDC) models using tissues collected from patients with metastatic cancer and assessed whether these models could be used as a tool for genome-based cancer treatment.

Methods

PDCs were isolated and cultured from malignant effusions including ascites and pleural fluid. Pathological examination, immunohistochemical analysis, and genomic profiling were performed to compare the histological and genomic features of primary tumors, PDCs. An exploratory gene expression profiling assay was performed to further characterize PDCs.

Results

From January 2012 to May 2013, 176 samples from patients with metastatic cancer were collected. PDC models were successfully established in 130 (73.6%) samples. The median time from specimen collection to passage 1 (P1) was 3 weeks (range, 0.5–4 weeks), while that from P1 to P2 was 2.5 weeks (range, 0.5–5 weeks). Sixteen paired samples of genomic alterations were highly concordant between each primary tumor and progeny PDCs, with an average variant allele frequency (VAF) correlation of 0.878. We compared genomic profiles of the primary tumor (P0), P1 cells, P2 cells, and patient-derived xenografts (PDXs) derived from P2 cells and found that three samples (P0, P1, and P2 cells) were highly correlated (0.99–1.00). Moreover, PDXs showed more than 100 variants, with correlations of only 0.6–0.8 for the other samples. Drug responses of PDCs were reflective of the clinical response to targeted agents in selected patient PDC lines.

Conclusion(s)

Our results provided evidence that our PDC model was a promising model for preclinical experiments and closely resembled the patient tumor genome and clinical response.

Novel strategy for a bispecific antibody: induction of dual target internalization and degradation

Activation of the extensive cross-talk among the receptor tyrosine kinases (RTKs), particularly ErbB family-Met cross-talk, has emerged as a likely source of drug resistance. Notwithstanding brilliant successes were attained while using small-molecule inhibitors or antibody therapeutics against specific RTKs in multiple cancers over recent decades, a high recurrence rate remains unsolved in patients treated with these targeted inhibitors. It is well aligned with multifaceted properties of cancer and cross-talk and convergence of signaling pathways of RTKs. Thereby many therapeutic interventions have been actively developed to overcome inherent or acquired resistance. To date, no bispecific antibody (BsAb) showed complete depletion of dual RTKs from the plasma membrane and efficient dual degradation. In this manuscript, we report the first findings of a target-specific dual internalization and degradation of membrane RTKs induced by designed BsAbs based on the internalizing monoclonal antibodies and the therapeutic values of these BsAbs. Leveraging the anti-Met mAb able to internalize and degrade by a unique mechanism, we generated the BsAbs for Met/epidermal growth factor receptor (EGFR) and Met/HER2 to induce an efficient EGFR or HER2 internalization and degradation in the presence of Met that is frequently overexpressed in the invasive tumors and involved in the resistance against EGFR- or HER2-targeted therapies. We found that Met/EGFR BsAb ME22S induces dissociation of the Met-EGFR complex from Hsp90, followed by significant degradation of Met and EGFR. By employing patient-derived tumor models we demonstrate therapeutic potential of the BsAb-mediated dual degradation in various cancers.

Serum level of hepatocyte growth factor is a novel marker of predicting the outcome and resistance to the treatment with trastuzumab in HER2-positive patients with metastatic gastric cancer

HER2-overexpression in tumor tissue is observed in 6 to 23% of advanced gastric cancer (GC) cases, and trastuzumab is an active molecular drug for these patients. There are no data available on whether serum levels of ligands are associated with the response and resistance to trastuzumab in HER2-positive patients with metastatic GC. HER2 screening of 502 patients with advanced gastric cancer was performed in our institution. Among these patients, 84 patients (16.8%) were diagnosed as HER2-positive, and those who were treated with trastuzumab and met the inclusion criteria were enrolled in the present study. Serum levels of ligands that affect the HER2 signal pathway were measured by an enzyme-linked immunosorbent assay. Forty-six HER2-positive patients were enrolled in this study, and 26 patients (56.5%) achieved a partial response to treatment with trastuzumab. Among several ligands, the serum level of hepatocyte growth factor (HGF) was significantly lower in responders compared with that in non-responders (p = 0.014). Multivariate analyses showed that a high level of serum HGF was a poor prognostic factor for overall survival (OS) compared with low levels of HGF (adjusted HR: 3.857, 95% CI: 1.309-11.361, p = 0.014). Among 25 patients without initial disease progression on the treatment with trastuzumab, the mean value of serum HGF at disease progression was significantly higher than that at pre-treatment (p = 0.041). As novel findings, our study indicated that serum level of HGF was associated with tumor shrinkage and time to progression of trastuzumab in HER2-positive patients with metastatic GC.

The association between EGFR expression and clinical pathology characteristics in gastric cancer

Objective

The aim of this study was to investigate epidermal growth factor receptor (EGFR) expression in the gastric cancer tissues and the association of EGFR expression with clinical pathology characteristics.

Methods

We firstly analyzed the copy number alteration of EGFR gene in gastric cancer by utilizing the online TCGA resources. We then gathered 71 cases of gastric cancer patients from February 2010 to February 2015 in our hospital. The cancer tissues and normal gastric tissues were tested for EGFR expression by immunohistochemical (IHC) staining and western blotting methods. The association of EGFR expression with clinical pathology characteristics and the prognosis value of EGFR expression were evaluated by the statistical software.

Results

The copy number of EGFR gene was found to be increased in gastric cancer patients. Western blotting confirmed that EGFR protein was obviously upregulated in tested gastric cancer tissues. Additionally, our IHC results showed that the positive rates of EGFR expression in gastric carcinoid tumors (CTs) and distant normal gastric tissues were 45.1% (32/71) and 25.0% (9/36), respectively. The former was significantly higher than the latter (P < 0.05). The EGFR-positive expression in CTs was related to tumor size, invasion depth, and lymphatic metastasis. The median survival of the EGFR-positive patients was 15.6 months, which was less than that (23.0 months) of the EGFR-negative patients [HR = 2.12, 95%CI: 1.29-4.10 (P < 0.05)]. Also, online survival analysis showed that high expression of EGFR predicted shorter overall survival of gastric cancer patients.

Conclusion

EGFR was highly expressed in gastric cancer tissues and associated with poor prognosis.

Molecular effects of Lapatinib in the treatment of HER2 overexpressing oesophago-gastric adenocarcinoma

BACKGROUND

Lapatinib, a dual EGFR and HER2 inhibitor has shown disappointing results in clinical trials of metastatic oesophago-gastric adenocarcinomas (OGAs), and in vitro studies suggest that MET, IGFR, and HER3 confer resistance. This trial applied Lapatinib in the curative neoadjuvant setting and investigated the feasibility and utility of additional endoscopy and biopsy for assessment of resistance mechanisms ex vivo and in vivo.

METHODS

Patients with HER2 overexpressing OGA were treated for 10 days with Lapatinib monotherapy, and then in combination with three cycles of Oxaliplatin and Capecitabine before surgery. Endoscopic samples were taken for molecular analysis at: baseline including for ex vivo culture +/- Lapatinib to predict in vivo response, post-Lapatinib monotherapy and at surgery. Immunohistochemistry (IHC) and proteomic analysis was performed to assess cell kinetics and signalling activity.

RESULTS

The trial closed early (n=10) due to an anastomotic leak in two patients for which a causative effect of Lapatinib could not be excluded. The reduction in Phosphorylated-HER2 (P-HER2) and P-EGFR in the ex vivo-treated biopsy demonstrated good correlation with the in vivo response at day 10. Proteomic analysis pre and post-Lapatinib demonstrated target inhibition (P-ERBB2, P-EGFR, P-PI3K, P-AKT, and P-ERK) that persisted until surgery. There was also significant correlation between the activation of MET with the level of P-Erk (P=0.0005) and P-PI3K : T-PI3K (total PI3K) ratio (P=0.0037). There was no significant correlation between the activation status of IGFR and HER3 with downstream signalling molecules.

CONCLUSIONS

Additional endoscopy and biopsy sampling for multiple biomarker endpoints was feasible and confirmed in vitro data that MET is likely to be a significant mechanism of Lapatinib resistance in vivo.

MET in gastric cancer--discarding a 10% cutoff rule

Aims

We aimed to develop a putative predictive biomarker score for future hepatocyte growth factor receptor (MET)‐targeted therapy of gastric cancer (GC).

Methods and results

MET expression and MET amplification were analysed by immunohistochemistry (IHC) and chromogenic in‐situ hybridization (CISH) in 470 GC patients. Immunostaining was documented with the HistoScore. The percentage area of MET‐amplified tumour cell clones was assessed by virtual microscopy. The expression of MET was heterogeneous in primary and metastatic GC. Immunostaining intensity (MET‐IHC 2+/3+) correlated with MET amplification and a positive MET status was defined by a combination of MET‐IHC 2+ or 3+ with MET amplification, or MET‐IHC 3+ without MET amplification. The prognostic significance of the MET status was independent from the percentage area of positive tumour cells (e.g. <10 versus ≥10%). MET‐positive GCs were microsatellite stable and of KRAS/PIK3CA wild‐type. MET‐positive GCs had a very poor prognosis, with a median survival of 5.4 months and a hazard ratio of 2.126.

Conclusions

A combination of immunohistochemistry and CISH is suitable to assess MET status. If MET status is used as a predictive biomarker, prospective studies should pay specific attention to adequate tissue sampling, should ignore cutoff values for tumour areas, may consider the KRAS and PIK3CA genotype as negative predictive markers and should carry out the analysis expeditiously.

The impact of concomitant genomic alterations on treatment outcome for trastuzumab therapy in HER2-positive gastric cancer

Clinical benefit from trastuzumab and other anti-human epidermal growth factor receptor-2 (HER2) therapies in patients with HER2-positive gastric cancer (GC) remains limited by primary or acquired resistance. We aimed to investigate the impact of concomitant molecular alterations to HER2 amplification on the clinical outcome of trastuzumab-treated patients. Using immunohistochemistry (IHC), copy number variations (CNVs), and Ion Ampliseq Cancer Panel, we analyzed the status of concomitant alterations in 50 HER2-positive advanced GC patients treated with trastuzumab in combination with other chemotherapeutic agents. The percentage of tumor samples with at least one concomitant alteration was 40% as assessed by IHC, 16% by CNVs, and 64% by Ampliseq sequencing. Median progression-free survival (PFS) was 8.0 months (95% confidence interval, 4.8-11.3). Patients were divided into two subgroups according to PFS values with a cutoff point of 8 months; results show that concomitant genomic alterations do not correlate with trastuzumab response. However, CNVs of CCNE1 significantly correlated (p < 0.05) with a shorter survival time. Our findings indicate that additional alterations implemented for prediction of clinical benefit from HER2-targeting agents in GC remained unclear. Further studies will be needed to elucidate the role of each specific biomarker and to optimize therapeutic approaches.