3541 POSTER HER2-positive advanced gastric cancer: similar HER2-positivity levels to breast cancer

Collagen Family and Other Matrix Remodeling Proteins Identified by Bioinformatics Analysis as Hub Genes Involved in Gastric Cancer Progression and Prognosis

Gastric cancer has remained in the top five cancers for over ten years, both in terms of incidence and mortality due to the shortage of biomarkers for disease follow-up and effective therapies. Aiming to fill this gap, we performed a bioinformatics assessment on our data and two additional GEO microarray profiles, followed by a deep analysis of the 40 differentially expressed genes identified. PPI network analysis and MCODE plug-in pointed out nine upregulated hub genes coding for proteins from the collagen family (COL12A1, COL5A2, and COL10A1) or involved in the assembly (BGN) or degradation of collagens (CTHRC1), and also associated with cell adhesion (THBS2 and SPP1) and extracellular matrix degradation (FAP, SULF1). Those genes were highly upregulated at the mRNA and protein level, the increase being correlated with pathological T stages. The high expression of BGN (p = 8 × 10⁻¹²), THBS2 (p = 1.2 × 10⁻⁶), CTHRC1 (p = 1.1 × 10⁻⁴), SULF1 (p = 3.8 × 10⁻⁴), COL5A1 (p = 1.3 × 10⁻⁴), COL10A1 (p = 5.7 × 10⁻⁴), COL12A1 (p = 2 × 10⁻³) correlated with poor overall survival and an immune infiltrate based especially on immunosuppressive M2 macrophages (p-value range 4.82 × 10⁻⁷–1.63 × 10⁻¹³). Our results emphasize that these genes could be candidate biomarkers for GC progression and prognosis and new therapeutic targets.

Prognostic significance of performing universal HER2 testing in cases of advanced gastric cancer

BACKGROUND

Trastuzumab significantly improves overall survival (OS) when added to cisplatin and fluoropyrimidine as a treatment for HER2-positive advanced gastric cancers (AGC). The aim of this study was to evaluate the impact of the gradual implementation of HER2 testing on patient prognosis in a national registry of AGC.

METHODS

This Spanish National Cancer Registry includes cases who were consecutively recruited at 28 centers from January 2008 to January 2016. The effect of missing HER2 status was assessed using stratified Cox proportional hazards (PH) regression.

RESULTS

The rate of HER2 testing increased steadily over time, from 58.3 % in 2008 to 92.9 % in 2016. HER2 was positive in 194 tumors (21.3 %). In the stratified Cox PH regression, each 1 % increase in patients who were not tested for HER2 at the institutions was associated with an approximately 0.3 % increase in the risk of death: hazard ratio, 1.0035 (CI 95 %, 1.001-1.005), P = 0.0019. Median OS was significantly lower at institutions with the highest proportions of patients who were not tested for HER2.

CONCLUSION

Patients treated at centers that took longer to implement HER2 testing exhibited worse clinical outcomes. The speed of implementation behaves as a quality-of-care indicator. Reviewed guidelines on HER2 testing should be used to achieve this goal in a timely manner.

Effects of combining erlotinib and RNA-interfered downregulation of focal adhesion kinase expression on gastric cancer

Objective

To investigate the synergistic effects of combining erlotinib and RNA-interference downregulation of focal adhesion kinase (FAK) expression on the proliferation, apoptosis, invasion and migration of the human gastric adenocarcinoma cell line AGS.

Methods

Cells were divided into five experimental groups: Group A, nontransfected control; Group B, transfected with empty vector; Group C, transfected with FAK-shRNA; Group D, erlotinib treatment; Group E, combination erlotinib treatment and transfected with FAK-shRNA. FAK protein levels were confirmed via Western blotting. Cell proliferation (CCK-8 assay, apoptosis (flow cytometry), cell invasion (transwell assay) and migration (scratch assay) were evaluated.

Results

RNA interference significantly decreased FAK protein levels. Cell proliferation, invasion and migration were significantly lower in Groups C, D and E compared with Group A, and significantly lower in Group E than in Groups C and D.

Conclusions

RNA interference effectively silences FAK expression and inhibits malignant cell proliferation and invasion in gastric cancer cells. The effect of FAK inhibition is increased by co-treatment with erlotinib.

Heterogeneity of amplification of HER2, EGFR, CCND1 and MYC in gastric cancer

BACKGROUND

Intra-tumor heterogeneity is a potential cause for failure of targeted therapy in gastric cancer, but the extent of heterogeneity of established (HER2) or potential (EGFR, CCND1) target genes and prognostic gene alterations (MYC) had not been systematically studied.

METHODS

To study heterogeneity of these genes in a large patient cohort, a heterogeneity tissue microarray was constructed containing 0.6 mm tissue cores from 9 different areas of the primary gastric cancers of 113 patients and matched lymph node metastases from 61 of these patients. Dual color fluorescence in-situ hybridization was performed to assess amplification of HER2, EGFR, CCND1 and MYC using established thresholds (ratio ≥ 2.0). Her2 immunohistochemistry (IHC) was performed in addition.

RESULTS

Amplification was found in 17.4% of 109 interpretable cases for HER2, 6.4% for EGFR, 17.4% for CCND1, and 24.8% for MYC. HER2 amplification was strongly linked to protein overexpression by IHC in a spot-by-spot analysis (p < 0.0001). Intra-tumor heterogeneity was found in the primary tumors of 9 of 19 (47.3%) cancers with HER2, 8 of 17 (47.0%) cancers with CCND1, 5 of 7 (71.4%) cancers with EGFR, and 23 of 27 (85.2%) cancers with MYC amplification. Amplification heterogeneity was particularly frequent in case of low-level amplification (<10 gene copies). While the amplification status was often different between metastases, unequivocal intra-tumor heterogeneity was not found in individual metastases.

CONCLUSION

The data of our study demonstrate that heterogeneity is common for biomarkers in gastric cancer. Given that both TMA tissue cores and clinical tumor biopsies analyze only a small fraction of the tumor bulk, it can be concluded that such heterogeneity may potentially limit treatment decisions based on the analysis of a single clinical cancer biopsy.

A phase IIa dose-finding and safety study of first-line pertuzumab in combination with trastuzumab, capecitabine and cisplatin in patients with HER2-positive advanced gastric cancer

BACKGROUND

Pertuzumab plus trastuzumab provides a more comprehensive blockade of HER2 signalling than trastuzumab alone. Therefore, we conducted a phase IIa study of the pharmacokinetics and safety of pertuzumab plus trastuzumab and chemotherapy in advanced gastric cancer (aGC).

METHODS

Patients received pertuzumab 840 mg for cycle 1 and 420 mg q3w for cycles 2-6 (Arm A) or pertuzumab 840 mg q3w for six cycles (Arm B). Trastuzumab, cisplatin and capecitabine were also given for six cycles, then trastuzumab q3w until disease progression or unmanageable toxicity. The co-primary endpoints were day 43 pertuzumab serum trough concentration (Cmin) and safety.

RESULTS

Thirty patients were randomised. Mean pertuzumab Cmin at day 43 was 40.0 μg ml(-1) (s.d.: 17.3) in Arm A and 62.7 μg ml(-1) (29.1) in Arm B. Mean day 43 Cmin in Arm A was ~37% lower than that seen in metastatic breast cancer. The safety profiles were similar between arms and treatment was well tolerated. Partial responses were achieved by 86% and 55% of patients in Arms A and B, respectively.

CONCLUSIONS

On the basis of the pharmacokinetic and safety data, the 840 mg q3w pertuzumab dose has been selected for a phase III study of pertuzumab, trastuzumab and chemotherapy in HER2-positive aGC.

Molecular targeted agents for gastric and gastroesophageal junction cancer

Despite recent improvements in surgical techniques and chemotherapy, advanced cancers of the stomach and gastroesophageal junction (GEJ) continue to have poor clinical outcomes. However, molecules intimately related to cancer cell proliferation, invasion, and metastasis have been studied as candidates for molecular targeted agents. Target molecules, such as the epidermal growth factor receptor, vascular endothelial growth factor receptor, and P13k/Akt/mTor pathway, as well as the insulin-like growth factor receptor, c-Met pathways, fibroblast growth factor receptor, and other pathways are considered to be promising candidates for molecular targeted therapy for gastric and GEJ cancer. In this review we focus on the recent developments in targeting relevant pathways in these types of cancer.

Novel investigational drugs for gastric cancer

BACKGROUND

Gastric cancer still represents a leading cause of death worldwide. Several cytotoxic agents have demonstrated activity and combination regimens improve progression-free survival, overall survival and quality of life. Nevertheless, now there is no standard therapy for advanced gastric cancer patients.

OBJECTIVE

To evaluate the role of new investigational agents.

METHODS

We analysed Phase I, II and III studies that evaluated tailored drugs directed against the epidermal growth factor receptor (EGFR), the c-erbB2, the vascular endothelial growth factor (VEGF), the vascular endothelial growth factor receptor (VEGFR), the matrix metalloproteinases (MMP) and the mammalian target of rapamycin (mTOR).

CONCLUSION

Data from Phase II trials indicate the potential of improved efficacy of chemotherapy when administered in combination with bevacizumab and cetuximab. Trastuzumab results are ongoing, while marimastat has not obtained clinical developments even if it has demonstrated to be an active drug in this setting of patients.

Recommendations on current approach to gastric cancer

The management of gastric cancer has been updated by the Grupo Español de Tratamiento de Tumores Digestivos (TTD). A multidisciplinary approach is essential in these patients including a precise diagnosis and staging and correct nutritional evaluation. For resectable disease, surgical resection remains the treatment mainstay and both perioperatory chemotherapy and postoperatory chemo-radiotherapy are considered standard complementary treatments. In advanced disease chemotherapy should always be considered. There are different reference schemes (TCF, XC, ECF, EXC) and the therapeutic option has to be individualised. Recently a phase III trial has shown a significant improvement in overall survival when trastuzumab is added to cisplatin-capecitabine or cisplatin-5-fluorouracil in patients with HER2+ advanced gastric cancer. Currently, there are several ongoing clinical trials evaluating the role of other new drugs against cellular targets. It would be desirable to incorporate biomarker studies in these trials in order to identify the best treatment for each patient.

Comparative study on overexpression of HER2/neu and HER3 in gastric cancer

BACKGROUND

Owing to the special importance of the HER family in tumorigenesis, the downstream signaling pathways and effectors have become the key molecules in the strategy of carcinoma-targeted therapy. Recent evidence that HER3 is responsible for tumor resistance to therapeutic agents targeting EGFR or HER2/neu, along with the new findings that HER3 is involved in the process of dedifferentiation of gastric cancer (GC) have highlighted the critical role of HER3 in cancer research. HER3 is becoming a new targeted molecule in cancer treatment. Here, we comparatively investigated the expression of HER2/neu and HER3 in gastric cancer of two pathologic types (intestinal type and diffuse type) using immunohistochemistry (IHC) and analyzed the correlation between overexpression of HER2 and HER3 and clinicopathologic parameters.

METHODS

An IHC study for HER2 and HER3 was performed on 102 formalin-fixed, paraffin-embedded specimens of GC-60 intestinal and 42 diffuse types. The correlation between overexpression of HER2 and HER3 and clinicopathologic parameters was statistically analyzed.

RESULTS

In the GC group, overexpression of HER2 and HER3 was detected in 19 (18.6%) and 14 (13.7%) of 102 GC patients, respectively. In a nontumorous group of 102 specimens, 5 were HER2-positive (4.9%) (18.6% vs. 4.9%, p < 0.01), and 2 were HER3-positive (2.0%) (13.7% vs. 2.0%, p < 0.01). No co-overexpression of HER2 and HER3 was observed. The intestinal type of GC exhibited a higher rate of HER2 overexpression than did the diffuse type (26.7% vs. 7.1%, p < 0.05), whereas the diffuse type of GC exhibited a significantly higher rate of HER3 overexpression than did the intestinal type (26.2% vs. 5.0%, p < 0.01). The overexpression rates of HER2 and HER3 in phase III-IV (TNM stage) disease were significantly higher than that in phase I-II disease (24.0% vs. 7.7%, p < 0.05 and 22.0% vs. 5.8%, p < 0.05, respectively). HER2 and HER3 overexpression was also correlated with a significantly worse survival (p = 0.046 and 0.024, respectively).

CONCLUSIONS

The selective overexpression of HER2 and HER3 in the two histologic types of gastric cancer is strongly associated with a poor prognosis. Being an important member of the HER family, HER3 may become another candidate for molecular-targeted therapy in gastric cancer, especially for the diffuse histologic type.