PTEN deficiency as a predictive biomarker of resistance to HER2-targeted therapy in advanced gastric cancer

Resistance to Anti-HER2 Therapies in Gastrointestinal Malignancies

Human epidermal growth factor 2 (HER2) is a tyrosine kinase receptor that interacts with multiple signaling pathways related to cellular growth and proliferation. Overexpression or amplification of HER2 is linked to various malignancies, and there have been decades of research dedicated to targeting HER2. Despite the landmark ToGA trial, progress in HER2-positive gastrointestinal malignancies has been hampered by drug resistance. This review examines current HER2 expression patterns and therapies for gastroesophageal, colorectal, biliary tract, and small bowel cancers, while dissecting potential resistance mechanisms that limit treatment effectiveness.

Targeting HER2/HER3 co-mutations in metastatic breast cancer: Case reports of exceptional responders to trastuzumab and pertuzumab therapy

BACKGROUND

Overexpression of HER2 plays an important role in cancer progression and is the target of multiple therapies in HER2-positive breast cancer. Recent studies have also highlighted the presence of activating mutations in HER2, and HER3 that are predicted to enhance HER2 downstream pathway activation in a HER2-dependent manner.

METHODS

In this report, we present two exceptional responses in hormone receptor-positive, HER2-nonamplified, HER2/HER3 co-mutated metastatic breast cancer patients who were treated with the anti-HER2-directed monoclonal antibodies, trastuzumab and pertuzumab.

RESULTS

Both patients acheived exceptional responses to treatment, suggesting that combined trastuzumab, pertuzumab, and endocrine therapy could be a highly effective therapy for these patients and our observations could help prioritize trastuzumab deruxtecan as an early therapeutic choice for patients whose cancers have activating mutations in HER2.

Clinical Implication of HER2 Aberration in Patients With Metastatic Cancer Using Next-Generation Sequencing: A Pan-Tumor Analysis

PURPOSE

Human epidermal growth factor receptor 2 (HER2) protein expression or gene amplification is a significant predictive biomarker for identifying patients with cancer, who may benefit from HER2-targeted therapy. The aim of this study was to survey the proportion of patients who had HER2 aberration and to investigate the correlation between HER2 amplification and HER2 overexpression in immunohistochemistry (IHC) as a real-world data.

METHODS

We surveyed the incidence of HER2 aberration including mutation (single-nucleotide variant [SNV]), amplification (copy-number variation), and fusion by next-generation sequencing (NGS) in 2,119 patients with cancer from Samsung Medical Center in South Korea.

RESULTS

Of 2,119 patients with cancer, 189 patients (8.9%) had HER2 aberration in their tumor specimen. Of 189 patients, 113 (5.3%) patients had HER2 amplification, 82 (3.9%) patients had HER2 mutations, and 11 (0.5%) patients had HER2 fusion. Of note, 10 patients (0.5%) had concurrent HER2 amplification and HER2 fusion. In addition, we identified that HER2 protein overexpression was strongly related to HER2 amplification by NGS. Of 74 patients with HER2 amplification only by NGS test, 64 patients (86.5%) had HER2 overexpression by IHC. Of 10 patients with concurrent HER2 amplification and fusion, 80% patients were HER2 overexpression. Among 51 patients with only HER2 mutation (SNV), 9 patients (17.6%) were HER2 (+). Interestingly, almost all patients with colorectal cancer (11 of 12) with HER2 amplification had very strong HER2 overexpression (3+) in their tumor specimen.

CONCLUSION

In conclusion, we showed that when patients with metastatic cancer receive NGS test, approximately 8.9% have HER2 aberrations in their tumor specimen. Most patients have HER2 amplification, and a small percentage of patients have HER2 fusion. A great majority of patients with HER2 amplification and/or HER2 fusion had HER2 (+) tumor by IHC.

PTEN is a predictive biomarker of trastuzumab resistance and prognostic factor in HER2-overexpressing gastroesophageal adenocarcinoma

Poor trastuzumab (Tmab) response of patients with human epidermal growth factor receptor 2-overexpressing gastric or gastroesophageal junction adenocarcinoma (HER2-GEA) is associated with the inhibition of phosphatase and tensin homolog (PTEN) expression. In this multicenter, retrospective observational study, pathological samples of patients with HER2-GEA receiving Tmab-combined chemotherapy were immunohistochemically analyzed for PTEN expression. The primary endpoints were disease control rate (DCR), progression-free survival (PFS), and overall survival (OS). We assessed the effect of conventional chemotherapy and Tmab alone or combined with PI3K pathway inhibitors in vitro in HER2-GEA cells with or without PTEN expression. Twenty-nine and 116 patients were in the PTEN-loss and PTEN-positive groups, respectively. In patients with the target region, DCR was significantly lower in PTEN-loss patients than in PTEN-positive patients (67% and 87%, respectively, p = 0.049). The multivariate analysis demonstrated that PTEN loss was significantly associated with shorter PFS (HR = 1.63, p = 0.035) and OS (HR = 1.83, p = 0.022). PTEN knockdown did not affect the cytostatic effect of 5-FU and cisplatin, whereas Tmab combined with the PI3K/mTOR inhibitor NPV-BEZ235 suppressed PTEN-knockdown cell proliferation. In patients with HER2-GEA, PTEN loss is a predictive biomarker of Tmab resistance and prognostic factor. Molecular-targeted therapy with a PI3K/mTOR inhibitor would be effective for HER2-GEA with PTEN loss.

PTEN and AKT1 Variations in Childhood T-Cell Acute Lymphoblastic Leukemia

Objective:

PTEN/AKT pathway deregulations have been reported to be associated with treatment response in acute leukemia. This study examined pediatric T-cell acute lymphoblastic leukemia (T-ALL) samples for PTEN and AKT1 gene variations and evaluated the clinical findings.

Materials and Methods:

Fifty diagnostic bone marrow samples of childhood T-ALL cases were investigated for the hotspot regions of the PTEN and AKT1 genes by targeted next-generation sequencing.

Results:

A total of five PTEN variations were found in three of the 50 T-ALL cases (6%). Three of the PTEN variations were first reported in this study. Furthermore, one patient clearly had two different mutant clones for PTEN. Two intronic single-nucleotide variations were found in AKT1 and none of the patients carried pathogenic AKT1 variations.

Conclusion:

Targeted deep sequencing allowed us to detect both low-level variations and clonal diversity. Low-level PTEN/AKT1 variation frequency makes it harder to investigate the clinical associations of the variants. On the other hand, characterization of the PTEN/AKT signaling members is important for improving case-specific therapeutic strategies.

Durable Clinical Response to Pyrotinib After Resistance to Prior Anti-HER2 Therapy for HER2-Positive Advanced Gastric Cancer: A Case Report

Background: Patients with advanced gastric cancer, especially the HER2-positive type, have a poor prognosis; there is a paucity of effective anti-HER2 drug therapies in patients who develop resistance to trastuzumab. Case presentation: We report the case of a 36-year-old male with HER2-positive gastric cancer with lung and liver metastases. The patient responded after treatment with trastuzumab combined with chemotherapy and attained a progression-free survival (PFS) of 17 months. Subsequently, the patient received apatinib that selectively inhibits the VEGFR2 and obtained an evident tumor response and a PFS of 8 months. When the disease progressed again, the regimen containing lapatinib failed. Then, the patient received treatment with nivolumab. However, he presented with hyper-progressive disease (HPD). Finally, he received a combination of capecitabine and pyrotinib, an irreversible dual TKI, acting on HER2 and EGFR. The tumor shrank markedly with this combination therapy. The mechanism of both HPD due to immunotherapy and the resistance to trastuzumab and lapatinib were investigated in this case. Loss of phosphatase and tensin homolog (PTEN) and new mutations of BRCA1 and KRAS were detected after resistance to trastuzumab and lapatinib. Conclusions: For patients with HER2-positive advanced gastric cancer who have developed resistance to trastuzumab, pyrotinib is a promising new agent, which can be used as salvage therapy.

Novel Biomarkers for Prediction of Response to Preoperative Systemic Therapies in Gastric Cancer

Preoperative chemo- and radiotherapeutic strategies followed by surgery are currently a standard approach for treating locally advanced gastric and esophagogastric junction cancer in Western countries. However, in a large number of cases, the tumor is extremely resistant to these treatments and the patients are exposed to unnecessary toxicity and delayed surgical therapy. The current clinical trials evaluating the combination of preoperative systemic therapies with modern targeted and immunotherapeutic agents represent a unique opportunity for identifying predictive biomarkers of response to select patients that would benefit the most from these treatments. However, it is of utmost importance that these potential biomarkers are corroborated by extensive preclinical and translational research. The aim of this review article is to present the most promising biomarkers of response to classic chemotherapeutic, anti-HER2, antiangiogenic, and immunotherapeutic agents that can be potentially useful for personalized preoperative systemic therapies in gastric cancer patients.

Comparison of Three Real-Time PCR Assays for the Detection of PIK3CA Somatic Mutations in Formalin-Fixed Paraffin Embedded Tissues of Patients with Breast Carcinomas

Breast cancer is the leading cause of cancer-related death in women worldwide. Mutations of the PIK3CA gene are found in approximately 25% of breast carcinomas and are reported as activators of the PI3K/AKT/mTOR pathway. This study aims to compare three assays for the somatic mutation detection of PIK3CA gene in FFPE tissues of patients with breast cancer. We compared Cobas® PIK3CA Mutation Test (Roche Diagnostics, Meylan, France), PCR amplification-refractory mutation system Scorpions® (ARMS) and High-Resolution Melting PCR assay (HRM) for the detection of PIK3CA mutations. Discrepant samples were assessed using Next Generation Sequencing (NGS). 46 FFPE breast carcinomas samples of patients treated for breast cancer have been assessed for PIK3CA mutations using the three PCR assays. Among the 46 samples, 17 (37.8%), 13 (28.36%) and 19 (41.3%) had a PIK3CA mutation, with Cobas®, ARMS and HRM assays respectively. Three different mutations of PIK3CA have been detected for one sample. Calculated kappa were 0.95[0.86;1] between Cobas® and HRM, 0.75[0.55;0.95] between Cobas® and ARMS and 0.72[0.51;0.92] between HRM and ARMS. Five samples were found with discrepant results. Our study shows that the Cobas® assay is suitable for PIK3CA mutation assessment in patients with breast cancer. HRM assay is also suitable for PIK3CA mutation assessment but requires a mutation characterization with a specific assay.

Long non‑coding RNA Fer‑1‑like family member 4 suppresses hepatocellular carcinoma cell proliferation by regulating PTEN in vitro and in vivo

The aim of the present study was to investigate the potential role of long non‑coding RNA Fer‑1‑like family member 4 (FER1L4) in the proliferation of hepatocellular carcinoma (HCC) through the regulation of phosphatase and tensin homolog (PTEN) expression. Reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) was used to detect the expression levels of FER1L4 and PTEN mRNA in HCC tissues, and western blotting was performed to measure the protein expression level of PTEN; MTT and colony formation assays were performed to detect the cell proliferative ability. Furthermore, nude mice were injected with transfected HCC cells and the tumor volume and weight were measured. The results indicated that FER1L4 was expressed at a low level in human HCC tissues compared with adjacent normal tissues. Functional studies indicated that FER1L4 may inhibit the proliferative ability of HCC cells. In addition, PTEN was highly expressed in HCC tissues compared with normal adjacent tissues and was positively associated with FER1L4. In addition, it was demonstrated that FER1L4 inhibited the proliferative ability of HCC cells in vitro, and silencing FER1L4 expression by small interfering RNAs promoted the growth of HCC tumors in vivo. Therefore, FER1L4 may be a potent therapeutic target for HCC.

Genomic markers of resistance to targeted treatments in gastric cancer: potential new treatment strategies

Gastric cancer is a highly heterogeneous disease, displaying a complex genomic landscape and an unfavorable outcome with standard therapies. Based on distinctive genomic alterations, novel targeted agents have been developed with the aim of personalizing treatments and improving patient outcome. However, a subgroup of patients is primarily treatment-resistant, and even in the initially sensitive population, secondary resistance emerges, thus limiting therapeutic benefit. In this review, we summarize the clinical data about standard targeted agents in gastric cancer, specifically anti-HER2 treatments and antivascular therapies. We also illustrate the available evidence regarding molecular mechanisms of resistance to these agents and we discuss potential strategies for new targeted treatments that could overcome such resistance.

Efficacy prediction of targeted therapy for gastric cancer: The current status (Review)

Despite significant progress in the treatment of gastric cancer (GC), the prognosis remains poor and the mortality is high. Targeted drugs have been incorporated into routine treatment to improve treatment efficacy. However, the therapy response is still below 50%. Therefore, there is a need to identify predictive factors for patient response to a specific drug in order to improve the efficacy of drug therapy. The present article reviewed the predictive factors for target therapy in GC, including epidermal growth factor receptor, human epidermal receptor 2, vascular endothelial growth factor family, molecules in the mesenchymal‑epithelial transition pathway and the mammalian target of rapamycin. Additionally, the present review described the interactions between these molecules and signaling pathways.

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.

Comprehensive expression profiles of gastric cancer molecular subtypes by immunohistochemistry: implications for individualized therapy

Gastric cancer (GC) is a leading cause of death. We aim to establish a clinically relevant assay that encompasses recent molecular classifications and provides useful clinical information in a large cohort of GC patients. A consecutive series of 438 GC patients that underwent palliative chemotherapy between 2014 and 2015 were assessed using 10 GC panels: EBER in-situ hybridization, immunohistochemistry for mismatch repair (MMR) proteins (MLH1, PMS2, MSH2, and MSH6), receptor tyrosine kinases (RTKs; HER2, EGFR, and MET), PTEN, and p53 protein. With a median of one aberration, 3.3 % of samples analyzed were Epstein-Barr virus (EBV)-positive; 4.8%, MMR-deficient. RTKs were overexpressed in 218 patients; EGFR was most commonly overexpressed (39.9%), followed by HER2 (13.5%) and MET (12.1%). Furthermore, 2.5 % and 10.7 % of cases had simultaneous overexpression of three and two RTKs, respectively. p53 overexpression/null tumors were identified in 259 patients (59.1%), and PTEN loss was identified in 89 patients (20.3%). EBV-positivity was mutually exclusive with MMR-deficiency, predominantly identified in male patients, and these tumors were undifferentiated with proximal location. p53 mutant type was significantly found predominantly in the EBV-negative (60.6% vs 14.3%, P=0.001) and HER2-positive (78.0% vs 56.2%, P=0.002) groups. We described a molecular spectrum of distinct GC subtypes using clinically applicable assay. This assay will provide a convenient screening tool and facilitate the development of targeted agents in clinical trials.

The Expression and Prognostic Impact of the PI3K/AKT/mTOR Signaling Pathway in Advanced Esophageal Squamous Cell Carcinoma

The abnormal phosphatase and tensin homolog expression and activated phosphoinositide-3 kinase/Protein kinase B (AKT)/mammalian target of rapamycin signaling pathway are involved in the progression of esophageal squamous cell carcinoma. By assessing the expression pattern of key components in the phosphoinositide-3 kinase/AKT/mammalian target of rapamycin signaling pathway by immunohistochemistry in tumor and nontumor esophageal mucosa from patients with esophageal squamous cell carcinomas, we aimed to carefully explore the relationship between the various protein expressions and clinicopathological factors, as well as patient outcome. A total of 145 tumor and 145 nontumor samples from patients with esophageal squamous cell carcinoma, collected from HuaShan Hospital (Shanghai, China) were evaluated. Clinical characteristics, the targeted protein expressions (including phosphatase and tensin homolog, phosphoinositide-3 kinase, AKT, p-AKT, mammalian target of rapamycin, p-mTOR, p70S6 kinase 1, p-P70S6K1, elongation initiation factor 4E binding protein-1, and p-4E-BP1, and survival rate were analyzed. Among them, phosphoinositide-3 kinase, AKT, p-AKT, mammalian target of rapamycin, p-mTOR, elongation initiation factor 4E binding protein-1, p70S6 kinase 1, and p-P70S6K1 proteins were significantly upregulated in tumor tissue. Conversely, phosphatase and tensin homolog was largely downregulated in tumor tissue, notably in pT3-T4 tumors. Low expression of phosphatase and tensin homolog whereas high expression of mammalian target of rapamycin signaling components in tumors was closely related to the presence of lymph node metastases and advanced TNM stage (all P < .05). Moreover phosphatase and tensin homolog, mammalian target of rapamycin, and p70S6 kinase 1 were correlated with overall survival as well as p-mTOR was correlated with progression-free survival (all P < .05). Overexpression of mammalian target of rapamycin was proved to be an independent adverse prognostic factor for overall survival in esophageal squamous cell carcinomas. Our results suggest that the phosphoinositide-3 kinase/AKT/mammalian target of rapamycin signaling pathway is activated in esophageal squamous cell carcinoma, with the low expression of phosphatase and tensin homolog and the high expression of the mammalian target of rapamycin component proteins (both total and phosphorylated) in tumor tissue. Our result might offer a new strategy for specific targeted therapy and prognostic assessment in esophageal cancer.

PTEN loss and level of HER2 amplification is associated with trastuzumab resistance and prognosis in HER2-positive gastric cancer

Background

Trastuzumab is an active agent against human epidermal growth factor receptor 2 (HER2)-positive gastric cancer (GC). This study aimed to characterize resistance to trastuzumab-based front-line chemotherapy in HER2+ GC patients and to establish factors predictive of this resistance.

Results

Among 129 HER2+ GC patients, 25% displayed rapid disease progression within 4 months from initiation of therapy. These patients showed a higher rate of signet ring cell histology, bone metastasis, poor performance status, frequent loss of PTEN expression, and low HER2 amplification index compared with patients who were progression-free for at least 4 months. In contrast, there was no significant difference in the frequency of the PIK3R1 variant. Multivariate analyses confirmed two independent molecular predictors for trastuzumab resistance: loss of PTEN expression and low HER2 amplification index (<5). Patients with one or both molecular predictors at diagnosis exhibited worse progression-free and overall survival compared to those without risk factors (p < 0.001 and p = 0.001, respectively).

Conclusion

In HER2+ GC patients, loss of PTEN expression and low HER2 AI correlated with resistance to trastuzumab-based therapy and dismal prognosis. Since patients harboring these molecular predictors are unlikely to respond to trastuzumab-based therapy, other novel therapeutic targets needed to be considered.

Methods

HER2+ GC patients who were treated with trastuzumab in combination with either 5-fluorouracil/cisplatin or capecitabine/cisplatin were enrolled. Clinicopathologic features and molecular alterations of HER2, phosphoinositide 3-kinase regulatory subunit 1 (PIK3R1), and phosphatase and tensin homolog (PTEN) were correlated with treatment outcome. Factors predictive of resistance were also explored.

Evolution of anti-HER2 therapies for cancer treatment

The development of HER2-directed monoclonal antibodies and tyrosine kinase inhibitors have provided benefits to cancer patients, as well as produced many insights into the biology of the ErbB receptor family. Current therapies based on ErbB family members have resulted in improved overall survival with associated improvements in quality of life for the cancer patients that respond to treatment. Compared to monotherapy using either two antibodies to block the HER2 receptor blockade or combinatorial approaches with HER2 antibodies and standard therapies has provided additional benefits. Despite the therapeutic success of existing HER2 therapies, personalising treatment and overcoming resistance to these therapies remains a significant challenge. The heterogeneous intra-tumoural HER2 expression and lack of fully predictive and prognostic biomarkers remain significant barriers to improving the use of HER2 antibodies. Imaging modalities using radiolabelled pertuzumab and trastuzumab allow quantitative assessment of intra-tumoural HER2 expression, HER2 antibody saturation and the success of different drug delivery systems to be assessed. Molecular imaging with HER2 antibodies has the potential to be a non-invasive, predictive and prognostic technique capable of influencing therapeutic decisions, predicting response and failure of treatments as well as providing insights into receptor recycling and signalling. Similarly, conjugating HER2 antibodies with novel toxic payloads or combining HER2 antibodies with cellular immunotherapy provide exciting new opportunities for the management of tumours overexpressing HER2. Future research will lead to higher therapeutic responses, lower toxicities and providing insight into the mechanisms of resistance to HER2-targeted treatments.

PTEN loss is associated with a poor response to trastuzumab in HER2-overexpressing gastroesophageal adenocarcinoma

BACKGROUND

Although trastuzumab improves the outcome of patients with human epidermal growth factor receptor 2 (HER2)-overexpressing gastric or gastroesophageal junction adenocarcinoma (collectively referred to as "gastroesophageal adenocarcinoma"; GEA), no clinical response is observed in a substantial population of patients. A predictive biomarker of trastuzumab response is required. The aim of this study was to evaluate whether the hyperactivation of the downstream phosphatidylinositol 3-kinase pathway, due to phosphatase and tensin homolog (PTEN) loss or PIK3CA mutations, could provide trastuzumab resistance in GEA.

METHODS

Expression of HER2 and PTEN, and PIK3CA gene mutations were screened in 264 surgically resected GEA specimens. The effects of PTEN knockdown on the response to trastuzumab on cell viability, HER2 downstream signaling, apoptosis, and cell cycle were evaluated in HER2-overexpressing NCI-N87 gastric adenocarcinoma and OE19 esophageal adenocarcinoma cell lines. Inhibition of xenograft tumor growth by trastuzumab was investigated in OE19 cells with or without PTEN knockdown. The PTEN expression and objective response were analyzed in 23 GEA patients who received trastuzumab-based therapy.

RESULTS

PTEN loss was identified in 34.5 % of HER2-overexpressing GEA patients, whereas PIK3CA mutations were rare (5.6 %). Trastuzumab-mediated growth suppression, apoptosis, and G₁ cell cycle arrest were inhibited by PTEN knockdown through Akt activation in NCI-N87 and OE19 cells. PTEN knockdown impaired the antiproliferative effect of trastuzumab in OE19 xenograft models. A clinical response was observed in 50 % of PTEN-positive tumors (9 of 18) but in no tumors with PTEN loss (none of 5).

CONCLUSIONS

PTEN loss was frequently found in HER2-overexpressing tumors, and was associated with a poor response to trastuzumab-based therapy in patients with GEA.

Immunohistochemical analysis of PTEN, HER2/neu, and ki67 expression in patients with gastric cancer and their association with survival

BACKGROUND

Considering the poor prognosis of patients with gastric cancer, molecular diagnostic and prognostic markers for this cancer should be established. The aims of our study were to assess the correlations between PTEN, HER2/neu, and Ki67 expressions and clinicopathological factors of gastric cancer patients in upper Egypt, as well as their influence on OS and DFS.

PATIENTS AND METHODS

In this descriptive-analytic study, 42 patients with gastric carcinoma treated by postioerative chemoradiation between 2004 and 2014. Pathological review was done. Immunohistochemical staining and evaluation were performed.

RESULTS

All the studied markers were significantly correlated with increased TNM stage. Her2/neu overexpression and positive Ki67 expression were significantly associated with histological grade. High percentage of positive Her2/neu and Ki67expression was found in gastric carcinoma tissue samples which lack PTEN expression. The one-year OS rate for the entire group (n=42) was 77.4%, whereas the DFS rate was 45%. Pathological T stage PTEN status significantly affected both OS (p=0.029 and 0.027 respectively) and DFS (p=0.006 and 0.012 respectively) rates. Multivariate Cox analyses showed that only pathological T stage was an independent prognostic factor affecting OS (P=0. 007, HR: 2.02; 95% CI: 1.2-3.38)and DFS(P<0.0001, HR: 2.69; 95% CI: 1.54-4.69).

CONCLUSION

All the studied molecular markers, was significantly correlated with pathological T stage that significantly affected both OS and DFS rates. These findings indicate that these markers have an important role in gastric cancer growth and dissemination so these markers can be used as a prognostic biomarker. In addition, therapies targeting Her2 and PTEN may help develop novel therapeutics for gastric cancer.

Current situation and trend of research for drug resistance in gastric cancer

Drug resistance of gastric cancer cells is one of the main reasons that lead to failure of chemotherapy in gastric cancer. Gastric cancer cells can be resistant to chemotherapeutic drugs and targeted drugs, which leads to poor therapeutic effects. Although the mechanisms of drug resistance of gastric cancer cells have long been investigated, no effective drug that can reverse the drug resistance of gastric cancer cells has been found. Therefore, it is important to reverse the drug resistance of gastric cancer cells to improve the prognosis of gastric cancer. In this paper, we review the mechanisms of drug resistance of gastric cancer cells to chemotherapeutic drugs and targeted drugs, summarize current situation for research of drug resistance of gastric cancer cells, and discuss the future development direction in this field.

Gastric cancer: somatic genetics as a guide to therapy

Gastric cancer is the leading cause of cancer-related mortality across the world, with poor prognosis and a median overall survival of ≤12 months for advanced stage gastric cancer. Environmental, genetic and other predisposing factors contribute to the development of gastric cancer and a predominant factor was found to be infection of Helicobacter pylori Advances in understanding the deranged signalling pathways that are critical for normal cellular homeostasis helped in the development of novel drugs that target specific proteins and pathways to curtail the growth of gastric cancer. Genetic studies revealed several single nucleotide polymorphisms, chromosomal aberrations and epigenetic alterations that likely play a major role in elevating the susceptibility to develop gastric cancer. Methylation pattern of specific genes may likely prove to be a valid biomarker for early detection of gastric cancer, but much progress is needed to establish specific markers. Important developments have been made in targeting human epidermal growth factor receptor-2 and vascular endothelial growth factor receptor 2 for treating advanced gastro-oesophageal junction cancer, using specific monoclonal antibodies. Lack of efficacy with regard to targeting other signalling pathways including mesenchymal-epithelial transition/hepatocyte growth factor and mammalian target of rapamycin is probably due to suboptimal patient selection for these clinical trials, which is probably due to the lack of appropriate biomarkers, to decide on responsive patient population. Besides the development of antagonists for the cell growth-related signalling pathways, advances are also being made to tackle gastric cancer by immunotherapies, targeting immune check-points, which may hold promise for better treatment options in future.

Predictive biomarkers for targeted and cytotoxic agents in gastric cancer for personalized medicine

Gastric cancer (GC) is the fourth most common cancer and the second leading cause of cancer. The treatment of GC remains challenging as the outcomes achieved with surgery alone or adjuvant or neoadjuvant chemotherapy and radiotherapy are relatively poor. New treatment strategies are emerging and are being tested in solid tumors including GC. Over the past few years, the treatment of metastatic colorectal cancer (CRC) has made great advances, but strategies to manage GC have improved little. Multiple drug resistance is common in GC chemotherapy and targeted therapy; some patients appear to receive treatment that is suboptimal or even inefficacious. Unfortunately, there are few validated predictive biomarkers to guide the tailored treatment of GC. ToGA and AVAGAST are two phase III trials that tested the efficacy and safety of targeted agents in advanced gastric cancer (AGC), and results clearly indicated that patients need to be selected and that targeted agents are the best hope for better results. This review aims to provide an overview of potential predictive biomarkers for cytotoxic and targeted agents in GC.

Application of next-generation sequencing in gastrointestinal and liver tumors

Malignant transformation of normal cells is associated with the evolution of genomic alterations. This concept has led to the development of molecular testing platforms to identify genomic alterations that can be targeted with novel therapies. Next generation sequencing (NGS) has heralded a new era in precision medicine in which tumor genes can be studied efficiently. Recent developments in NGS have allowed investigators to identify genomic predictive makers and hereditary mutations to guide treatment decision. The application of NGS in gastrointestinal cancers is being extensively studied but continues to face substantial challenges. In our review, we discuss various NGS platforms and highlight their role in identifying familial mutations and markers of response or resistance to cancer therapy. We also provide a balanced discussion of the challenges that limit the routine use of NGS in clinical practice.

Individualized molecular targeted therapy for gastric cancer based on human epidermal growth factor receptor 2 gene detection

Compared with traditional chemotherapy drugs, molecular targeted drugs have the advantages of high specificity and fewer side effects. Human epidermal growth factor receptor 2 (HER2) has been a focus of research in recent years, although the relationship between HER2 and prognosis of gastric cancer remains controversial. With the advent of trastuzumab, lapatinib, pertuzumab and other anti-HER2 drugs, many clinical studies have achieved good results; however, there are still some patients with unsatisfactory results due to the occurrence of drug resistance. Finding solutions to overcome drug resistance can increase the efficacy, and individualized molecular targeted therapy can better benefit gastric cancer patients.

Molecular targeted therapy for the treatment of gastric cancer

Despite the global decline in the incidence and mortality of gastric cancer, it remains one of the most common malignant tumors of the digestive system. Although surgical resection is the preferred treatment for gastric cancer, chemotherapy is the preferred treatment for recurrent and advanced gastric cancer patients who are not candidates for reoperation. The short overall survival and lack of a standard chemotherapy regimen make it important to identify novel treatment modalities for gastric cancer. Within the field of tumor biology, molecular targeted therapy has attracted substantial attention to improve the specificity of anti-cancer efficacy and significantly reduce non-selective resistance and toxicity. Multiple clinical studies have confirmed that molecular targeted therapy acts on various mechanisms of gastric cancer, such as the regulation of epidermal growth factor, angiogenesis, immuno-checkpoint blockade, the cell cycle, cell apoptosis, key enzymes, c-Met, mTOR signaling and insulin-like growth factor receptors, to exert a stronger anti-tumor effect. An in-depth understanding of the mechanisms that underlie molecular targeted therapies will provide new insights into gastric cancer treatment.

Competing endogenous RNA networks and gastric cancer

Recent studies have showed that RNAs regulate each other with microRNA (miRNA) response elements (MREs) and this mechanism is known as “competing endogenous RNA (ceRNA)” hypothesis. Long non-coding RNAs (lncRNAs) are supposed to play important roles in cancer. Compelling evidence suggests that lncRNAs can interact with miRNAs and regulate the expression of miRNAs as ceRNAs. Several lncRNAs such as H19, HOTAIR and MEG3 have been found to be associated with miRNAs in gastric cancer (GC), generating regulatory crosstalk across the transcriptome. These MRE sharing elements implicated in the ceRNA networks (ceRNETs) are able to regulate mRNA expression. The ceRNA regulatory networks including mRNAs, miRNAs, lncRNAs and circular RNAs may play critical roles in tumorigenesis, and the perturbations of ceRNETs may contribute to the pathogenesis of GC.

Upfront molecular testing in patients with advanced gastro-esophageal cancer: Is it time yet?

INTRODUCTION

Targeting HER2 has improved outcomes in metastatic GE (mGE) cancer. In this study, we aim to explore the feasibility of molecular profiling in patients with refractory mGE cancer in routine clinical practice.

METHODS

Archival formalin-fixed, paraffin-embedded (FFPE) samples for patients with mGE were analyzed with commercially available targeted next generation sequencing (NGS) and/or FISH for MET amplification. We also reviewed the patients' medical records for concurrent HER 2 testing.

RESULTS

Tumor samples from 99 patients with mGE cancer were analyzed as follows: NGS (N = 56), FISH for MET amplification (N = 65), IHC and/or FISH for HER2 (N = 87). Of patients who underwent NGS, 50/56 (89%) had at least one actionable molecular alteration. The most notable actionable alterations included cell cycle abnormalities (58%), HER2 amplification (30%), PI3KCA mutation (14%), MCL1 amplification (11%), PTEN loss (9%), CDH1 mutation (2%) and MET amplification (5%). Ninety-two percent (12/13) of patients with HER2 amplification by NGS were positive for HER2 by IHC and/or FISH. In contrast, only 12/18 (66%) patients positive for HER2 by IHC and/or FISH demonstrated HER2 amplification by NGS.

CONCLUSION

Comprehensive molecular testing is feasible in clinical practice and provides a platform for screening patients for molecularly guided clinical trials and available targeted therapies.

Monitoring Trastuzumab Resistance and Cardiotoxicity: A Tale of Personalized Medicine

While approval of trastuzumab, a recombinant monoclonal antibody directed against HER2, along with a diagnostic kit to detect breast cancers which are positive for HER2 overexpression, has advanced a new era of stratified and personalized medicine, it also created several challenges to our scientific and clinical practice. These problems include trastuzumab resistance and trastuzumab-induced cardiotoxicity. In this review, we will summarize data from the literature regarding mechanisms of trastuzumab resistance and trastuzumab-induced cardiotoxicity and present some promising model systems that may advance our understanding of these mechanisms. Our discussion will include development of circulating tumor cells and circulating tumor DNA for monitoring tumor burden, of patient-derived xenograft models for preclinical testing of novel therapies, and of novel therapeutic strategies for trastuzumab-resistance and possible integration of these strategies in the design of co-clinical studies for testing in relevant patient subpopulations.