HER2 Status in Gastric Cancer: Comparison between Primary and Distant Metastatic Disease

Systemic investigation of inetetamab in combination with small molecules to treat HER2-overexpressing breast and gastric cancers

Most patients with metastatic breast cancer or gastric cancer who are treated with trastuzumab, an anti-HER2 monoclonal antibody, become refractory to the drug within a year after the initiation of treatment. Although the combination of trastuzumab with pertuzumab produced synergetic effects in the treatment of HER2-overexpressing cancers, not all patients with HER2 overexpression benefited from the trastuzumab plus pertuzumab combination. To improve the clinical benefits of trastuzumab, we systemically investigated the combination of inetetamab (Cipterbin), an analog of trastuzumab, with a variety of small molecules, including tyrosine kinase inhibitors (TKIs) and chemotherapeutic agents in vivo. We showed that pan-TKIs-induced synergistic antitumor effects with inetetamab in the treatment of these two types of cancers and that adding chemotherapeutic agents to the existing TKI plus anti-HER2 monoclonal antibody combination strategies induced additional inhibitory effects, suggesting that such combination strategies may be choices for the treatment of these two tumors. Thus, combination therapies targeting distinct and broad pathways that are essential for tumor growth and survival can be effective for treating metastatic breast cancers and gastric cancers.

Expression heterogeneity of ABC-transporter family genes and chemosensitivity genes in gastric tumor, carcinomatosis and lymph node metastases

Introduction. Metastatic tumors (particularly gastric cancer) have been found to be characterized by heterogeneity between the primary tumor and metastases. This type of heterogeneity comes to the fore when treating primary-metastatic forms of tumor and is an important reason for the low effectiveness of their treatment. In this regard, comparative analysis of ABC-transporter gene expression and chemosensitivity genes will allow to characterize to a certain extent the resistance and sensitivity of primary tumor, carcinomatosis and metastases to therapy and provide the basis for personalized treatment approach.Aim. To evaluate expression heterogeneity of ABC-transporter genes and chemosensitivity genes in gastric tumor, carcinomatosis and lymph node metastases.Materials and methods. Overall 41 patients with disseminated gastric cancer stage IV with carcinomatosis of peritoneum were included in the investigation. All patients underwent surgery according to Roux palliative gastrectomy. After surgery patients underwent chemotherapy depending on indications. RNA was isolated using RNeasy Plus mini kit (Qiagen, Germany). The expression level of ABC transporter genes (ABCB1, ABCC1, ABCC2, ABCC5, ABCG1, ABCG2) and chemosensitivity genes (BRCA1, RRM1, ERCC1, TOP1, TOP2α, TUBβ3, TYMS, GSTP1) was assessed by reverse transcription polymerase chain reaction (RT-PCR) in primary tumor, carcinomatosis and lymph node metastases.Results. The expression levels of the genes under study were shown to vary widely. For ABC transporter genes, ABCG1 (3.1 ± 1.1; max 32.0), ABCG2 (7.9 ± 2.3; max 54.1), ABCG2 (9.6 ± 3.8; max 101.0) were the most expressed genes in gastric tumor tissue, carcinomatosis and lymph node metastasis, respectively. Hyperexpression among chemosensitivity genes at all three sites was characteristic only of TOP2α (17.2 ± 6.0; max. 161.9; 10.8 ± 4.1; max. 105.1; 35.3 ± 0.8; max. 439.6, respectively). We found that TOP2α and BRCA1 gene expression levels were higher in lymph node metastasis compared with gastric tumor tissue and carcinomatosis (at p = 0.005 and p = 0.001). Whereas ABCC1 gene expression was statistically significantly higher in carcinomatosis (p = 0.03).Conclusion. Thus, a high level of expression heterogeneity is observed in gastric cancer, which affects the expression patterns of various genes in different localizations. The expression profile can be used to determine the level of heterogeneity and approach to personalized therapy tactics.

Current prognostic and predictive biomarkers for gastrointestinal tumors in clinical practice

The pathologist emerged in the personalized medicine era as a central actor in the definition of the most adequate diagnostic and therapeutic algorithms. In the last decade, gastrointestinal oncology has seen a significantly increased clinical request for the integration of novel prognostic and predictive biomarkers in histopathological reports. This request couples with the significant contraction of invasive sampling of the disease, thus conferring to the pathologist the role of governor for both proper pathologic characterization and customized processing of the biospecimens. This overview will focus on the most commonly adopted immunohistochemical and molecular biomarkers in the routine clinical characterization of gastrointestinal neoplasms referring to the most recent published recommendations, guidelines and expert opinions.

CAR-T Cell Therapy-An Overview of Targets in Gastric Cancer

Gastric cancer (GC) is one of the most commonly diagnosed malignancies and, unfortunately, still has a high mortality rate. Recent research points to CAR-T immunotherapy as a promising treatment for this disease. Using genetically engineered T cells designed to target a previously selected antigen, researchers are able to harness the natural anti-tumor activity of T cells. For therapy to be successful, however, it is essential to choose antigens that are present on tumor cells but not on healthy cells. In this review, we present an overview of the most important targets for CAR-T therapy in the context of GC, including their biologic function and therapeutic application. A number of clinical studies point to the following as important markers in GC: human epidermal growth factor receptor 2, carcinoembryonic antigen, mucin 1, epithelial cell adhesion molecule, claudin 18.2, mesothelin, natural-killer receptor group 2 member D, and folate receptor 1. Although these markers have been met with some success, the search for new and improved targets continues. Key among these novel biomarkers are the B7H6 ligand, actin-related protein 2/3 (ARP 2/3), neuropilin-1 (NRP-1), desmocollin 2 (DSC2), anion exchanger 1 (AF1), and cancer-related antigens CA-72-4 and CA-19-9.

Local and Central Evaluation of HER2 Positivity and Clinical Outcome in Advanced Gastric and Gastroesophageal Cancer-Results from the AGMT GASTRIC-5 Registry

Trastuzumab in combination with a platinum and fluorouracil is the treatment of choice for patients with advanced human epidermal growth factor receptor 2 (HER2) positive gastric cancer and gastroesophageal junction (GEJ) cancer. Pathological assessment of the HER2 status in gastric/GEJ cancer, however, still remains difficult. However, it is a crucial prerequisite for optimal treatment. The GASTRIC-5 registry was designed as an observational, multi-center research initiative comparing local and central HER2 testing. HER2 status was assessed by immunohistochemistry (IHC) and in equivocal cases (IHC score 2+) by additional in-situ hybridization. Between May 2011 and August 2018, tumor samples of 183 patients were tested in local and central pathology laboratories, respectively. Central testing revealed HER2 positivity in 38 samples (21%). Discordant HER2 results were found in 12% (22 out of 183) with locally HER2 positive/centrally HER2 negative results (9%, 17 out of 183), exceeding locally HER2 negative/centrally HER2 positive results (3%, 5 out of 183). Centrally confirmed HER2 positive patients receiving trastuzumab-based palliative first-line therapy showed a longer median overall survival compared to centrally HER2 positive patients not receiving trastuzumab (17.7 months (95% CI: 10,870–24,530) vs. 6.9 months (95% CI: 3.980–9.820), p = 0.016). The findings of the GASTRIC-5 registry corroborate the challenge of HER2 testing in gastric/GEJ cancer and highlight the necessity for central quality control to optimize individual treatment options. Centrally HER2 positive patients not receiving trastuzumab had the worst outcome in a Western real-world gastric/GEJ cancer cohort.

Detection of ERBB2 (HER2) Gene Amplification Events in Cell-Free DNA and Response to Anti-HER2 Agents in a Large Asian Cancer Patient Cohort

Background: HER2 antagonists have marked activity and are approved for the treatment of HER2 overexpressing breast and gastric cancers. Recent studies have shown that ERBB2 (HER2) gene amplification and overexpression may also be actionable in other tumor types. Inter- and intratumoral heterogeneity in HER2 status, however, poses a significant challenge in identifying patients that may benefit from HER2-targeted therapies. ERBB2 amplification as identified by circulating cell-free DNA (cfDNA), which circumvents tissue heterogeneity issues, is emerging as a robust biomarker predictive of response to anti-HER2 agents. Here, the prevalence and genomic landscape of ERBB2 alterations detectable by next-generation sequencing (NGS) of cfDNA was evaluated in a large cohort of Asian patients with advanced solid tumors. Methods: Results were queried for consecutive patients (n = 469) tested by a comprehensive 70/73-gene cfDNA NGS assay (Guardant360®) between November 2015 and June 2018. Patients with ERBB2 gene alterations including copy number amplifications (CNAs), single nucleotide variants (SNVs), and insertion-deletions (indels) were identified. Results: ERBB2 alterations were detected in 52 patients (11.1%); ERBB2 SNVs, CNAs, and indels were found in 27 (5.8%), 27 (5.8%), and 10 (2.1%) patients, respectively. ERBB2 amplification was most frequently identified in gastric (21.4%; 6/28), colorectal (11.1%; 5/45), lung (3.9%; 9/231), and breast (3.2%; 1/31) cancer patients. ERBB2 amplification was often mutually exclusive with other oncogenic alterations in gastric (83.3%; 5/6) and colorectal (60%; 3/5) cancer patients. ERBB2 copy number gains were also highest in gastric and colorectal cancers (median 4.8 and 6.6, respectively). We further report two cases of advanced gastric cancer patients, one treatment naïve, and the other having failed four lines of therapy, whose ERBB2 CNAs were identified by cfDNA and derived clinical benefit from HER2-based therapies. Conclusion: Our data indicate that ERBB2 amplification is a common event in solid tumors among Asian cancer patients. High ERBB2 incidence and copy number gains were observed in gastric and colorectal cancer patients, often in the absence of other oncogenic mutations, underscoring its likely role as the driver alteration in those settings. Finally, we show the potential of comprehensive cfDNA testing in identifying patients who are most likely to benefit from HER2-targeted therapies.

Validated clinico-pathologic nomogram in the prediction of HER2 status in gastro-oesophageal cancer

Background

HER2 is the only validated predictive biomarker in gastro-oesophageal carcinoma (GOC). However, several factors, such as heterogeneity in protein expression, shortage of evaluable tumour tissue and need for quick target assessment, underline the usefulness of a pre-screening tool in order to anticipate HER2 status.

Methods

Data from 723 consecutive GOC analysed for HER2 at four Italian Institutions were collected. HER2 positivity was defined as 3+ by immunohistochemistry (IHC) or 2+ with gene amplification by in situ hybridisation (ISH). A multivariate logistic regression model was built using data from 413 cases, whereas 310 patients served as validation cohort. C-index, visual inspection of the calibration plot, Brier score and Spiegelhalter z-test were used to assess the performance of the nomogram.

Results

HER2 positive rate was 17.4%. Four variables were retained after adjustment in the final model: grading, Lauren’s histotype, pathologic material analysed (surgical specimen/biopsy) and site of tissue collection (primary tumour/metastases). Visual inspection of the calibration plot revealed a very good overlap between predicted and observed probabilities, with a Brier score of 0.101 and a non-significant Spiegelhalter z-test (P = 0.319). C-index resulted in 0.827 (95%CI 0.741–0.913).

Conclusion

A simple nomogram based on always-available pathologic information accurately predicts the probability of HER2 positivity in GOC.

Detection of HER2 Amplification in Circulating Tumor Cells of HER2-Negative Gastric Cancer Patients

A key to the successful use of targeted cancer therapy is the ability to preselect patients who are likely to benefit from the treatment according to molecular markers. Assessment for predicting therapy response is mostly done using tumor biopsies. However, these might not truly represent all of the patient's malignant cells because of tumor heterogeneity and/or clonal evolution during disease progression. One potential strategy that can complement primary tumor biopsy is the analysis of circulating tumor cells (CTCs). In this study, we analyzed CTCs of patients with gastric cancer (GC) to find those who were likely to benefit from trastuzumab therapies. We developed an imaging-based method that enabled CTC identification simultaneously with evaluation of HER2 gene amplification (the 3D-IF-FISH method). Then we performed a study enrolling 101 GC patients in whom we analyzed CTCs by both 3D-IF-FISH and an FDA-approved CellSearch system. As compared with the CellSearch system, 3D-IF-FISH methods identified a higher number of patients whose primary tumors were HER2- but who had HER2+ CTCs, suggesting that the 3D-IF-FISH method is effective in preselecting patients for trastuzumab therapies. To demonstrate this, we performed an exploratory clinical study to evaluate the clinical benefits of trastuzumab treatment for advanced GC patients (n = 15) whose primary tumors were HER2-, but whose CTCs showed HER2 amplification. An interim evaluation after the first stage showed that these preselected patients had response rates comparable to those reported in the trastuzumab-plus-chemotherapy arm of the ToGA study. The present study offers a new, non-invasive strategy to select patients who are likely to benefit from trastuzumab-based therapies, despite their primary biopsy being HER2-negative. (UMIN ID: UMIN000008622).

Brain metastasis in gastroesophageal adenocarcinoma and HER2 status

The increased survival of patients with gastroesophageal adenocarcinoma (GAD) following improvements in treatment has been accompanied by a rising incidence of secondary brain metastasis. HER2 amplification/overexpression, which has been associated with an increased risk of brain metastasis in breast cancer, is found in about 20% of patients with GAD. The aim of this study was to evaluate the effect of HER2 status on brain metastasis in GAD. The database of a tertiary cancer center was searched for patients with GAD diagnosed in 2011-2015, and data were collected on clinical characteristics, brain metastasis, HER2 status, and outcome. We identified 404 patients with a confirmed diagnosis of GAD. HER2 results were available for 298: 69 (23.2%) positive and 227 negative. Brain metastasis developed in 15 patients with GAD (3.7%); HER2 results, available in 13, were positive in 6, negative in 6, and equivocal in 1. The brain metastasis rate was significantly higher in HER2-positive than HER2-negative patients with GAD (6/69, 8.7% vs. 6/227, 2.6%; RR = 3.3, 95% CI 1.1-9.9, p = 0.034). Median overall survival from diagnosis of brain metastasis was 2.3 months, with no significant difference by HER2 status. HER2 positive GAD patients may be at increased risk to develop BM. Clinicians should maintain a lower threshold for performing brain imaging in patients with HER2-positive GAD given their increased risk of brain metastasis. The role of anti-HER2 agents in the development and treatment of brain metastasis in GAD warrants further study.