Human epidermal growth factor receptor 2 testing in gastric cancer: recommendations of an Asia-Pacific task force

Human epidermal growth factor receptor 2 (HER2) testing in gastric and gastroesophageal junction cancer is an evolving area in clinical practice that has particular relevance to Asia-Pacific countries, which face a high incidence of these diseases. A growing body of evidence demonstrates that HER2-targeted therapy improves survival for patients with HER2-positive advanced disease, and drives the need for high-quality testing procedures to identify patients who will respond to treatment. However, various factors challenge day-to-day testing of gastric specimens in these countries, to a degree greater than that observed for breast specimens. Recommendations for HER2 testing of gastric cancer specimens were published as a result of the Trastuzumab for Gastric Cancer (ToGA) trial. The guidelines proposed in this manuscript build on these recommendations and emphasize local testing environments, particularly in Asia-Pacific countries. A multidisciplinary task force comprising experts from Asia-Pacific who actively work and provide education in the area was convened to assess the applicability of existing recommendations in the Asia-Pacific region. The resulting recommendations reported here highlight and clarify aspects of testing that are of particular relevance to the region, and notably emphasize multidisciplinary collaborations to optimize HER2 testing quality.

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

Growth factor receptors, often carrying tyrosine kinase activities in their cytoplasmic domains, are overexpressed in many cancers. Coactivation of receptor tyrosine kinases (RTKs) plays a critical role in tumor response to targeted therapeutics. We examined concomitant overexpression of EGFR and MET in patients with HER2(+) and HER2(-) gastric cancers (GCs). Tissue microarray samples obtained from 1,589 GC patients who received R0 gastrectomy with extensive node dissection and adjuvant chemoradiationtherapy were analyzed by immunohistochemistry and fluorescence in situ hybridization. HER2(+) was observed in 169 patients (11%). Out of 169 HER2(+) patients, 15 (9%) were EGFR(+) and MET(+) , 29 (17%) were EGFR(+) , 37 (22%) were MET(+) and the remaining 88 patients (52%) were HER2(+) only, without concomitant EGFR or MET overexpression. Greater number of overexpressed RTKs correlated with younger age (p < 0.001), larger tumor size (p = 0.027), intestinal histology (p < 0.001) and shorter overall survival (p = 0.002). The mean overall survival was 113 months for HER2(-) /EGFR(-) /MET(-) and 63 months for HER2(+) /EGFR(+) /MET(+) subgroups. Patients with HER2(+) /EGFR(+) /MET(+) GCs had a substantial risk of death with a hazard ratio of 3.01 (95% CI: 1.54-5.90), compared with HER2(-) /EGFR(-) /MET(-) GC patients. Using patient-derived tumor cell models isolated from pericardial effusion of HER2(+) and MET(+) GC cases, we demonstrated that the combination of HER2-inhibitor (lapatinib) and MET-inhibitor offered a more profound inhibition in the ERK/AKT pathway and cell proliferation than lapatinib alone. Co-overexpression of RTKs was demonstrated in small subsets of GC associated with aggressive behavior and in these cases, combination therapy may be considered as potential treatment options.

Novel roles for β-arrestins in the regulation of pharmacological sequestration to predict agonist-induced desensitization of dopamine D3 receptors

BACKGROUND AND PURPOSE

In addition to typical GPCR kinase (GRK)-/β-arrestin-dependent internalization, dopamine D3 receptor employed an additional GRK-independent sequestration pathway. In this study, we investigated the molecular mechanism of this novel sequestration pathway.

EXPERIMENTAL APPROACH

Radioligand binding, flow cytometry and cell surface biotinylation assay were used to characterize trafficking properties of D2 and D3 receptors. Serine/threonine and N-linked glycosylation mutants of the D3 receptor were utilized to locate receptor regions involved in pharmacological sequestration and desensitization. Various point mutants of the D2 and D3 receptors, whose sequestration and desensitization properties were altered, were combined with knockdown cells of GRKs or β-arrestins to functionally correlate pharmacological sequestration and desensitization.

KEY RESULTS

The D3 receptor, but not the D2 receptor, showed characteristic trafficking behaviour in which receptors were shifted towards the more hydrophobic domains within the plasma membrane without translocation into other intracellular compartments. Among various amino acid residues tested, S145/S146, C147 and N12/19 were involved in pharmacological sequestration and receptor desensitization. Both pharmacological sequestration and desensitization of D3 receptor required β-arrestins, and functional relationship was observed between two processes when it was tested for D3 receptor variants and agonists.

CONCLUSIONS AND IMPLICATIONS

Pharmacological sequestration of D3 receptor accompanies movement of cell surface receptors into a more hydrophobic fraction within the plasma membrane and renders D3 receptor inaccessible to hydrophilic ligands. Pharmacological sequestration is correlated with desensitization of the D3 receptor in a Gβγ- and β-arrestin-dependent manner. This study provides new insights into molecular mechanism governing GPCR trafficking and desensitization.

Upper abdominal gadoxetic acid-enhanced and diffusion-weighted MRI for the detection of gastric cancer: Comparison with two-dimensional multidetector row CT

AIM

To evaluate the diagnostic performance of abdominal magnetic resonance imaging (MRI) for the detection of gastric cancer in comparison with that of two-dimensional (2D) multidetector row computed tomography (CT).

MATERIALS AND METHODS

The study included 189 patients with 170 surgically confirmed gastric cancers and 19 patients without gastric cancer, all of whom underwent gadoxetic acid-enhanced MRI with diffusion-weighted (DW) imaging, and multidetector contrast-enhanced abdominal CT imaging. Two observers independently analysed three sets of images (CT set, conventional MRI set, and combined conventional and DW MRI set). A five-point scale for likelihood of gastric cancer was used. Diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were evaluated. Quantitative [apparent diffusion coefficient (ADC) analyses with Mann-Whitney U-test were conducted for gastric cancers and the nearby normal gastric wall.

RESULTS

The diagnostic accuracy and sensitivity for detection of gastric cancer were significantly higher on combined conventional and DW MRI set (77.8-78.3%; 75.3-75.9%) than the CT imaging set (67.7-71.4%; 64.1-68.2%) or the conventional MRI set (72-73%; 68.8-70%; p < 0.01). In particular, for gastric cancers with pT2 and pT3, the combined conventional and DW MRI set (91.6-92.6%) yielded significantly higher sensitivity for detection of gastric cancer than did the CT imaging set (76.8-81.1%) by both observers (p < 0.01). The mean ADC of gastric cancer lesions (1 ± 0.23 × 10(-3) mm(2)/s) differed significantly from that of normal gastric wall (1.77 ± 0.25 × 10(-3) mm(2)/s; p < 0.01).

CONCLUSION

Abdominal MRI with DW imaging was more sensitive for the detection of gastric cancer than 2D-multidetector row CT or conventional MRI alone.

Distinctive role of 6-month teriparatide treatment on intractable bisphosphonate-related osteonecrosis of the jaw

The administration of teriparatide (TPTD) in conjunction with periodontal care could provide faster and more favorable clinical outcomes in previously refractory bisphosphonate-related osteonecrosis of the jaws (BRONJ) cases compared to conventional dental care, combination of surgery and antimicrobial treatment. We also found that underlying vitamin D levels might influence the response to TPTD treatment.

INTRODUCTION

Treatment of BRONJ is quite challenging and there are no standard treatment modalities. In this retrospective, longitudinal study, we examined whether additional TPTD administration could be beneficial for the resolution of BRONJ lesions compared to conservative management, such as antimicrobial treatment with or without surgery, and also studied the factors influencing the response to TPTD.

METHODS

Twenty-four cases of intractable BRONJ were included: 15 subjects were assigned to the TPTD group and the other 9 subjects, who refused TPTD administration, were assigned to the non-TPTD group. All subjects in both groups continued calcium and vitamin D supplementation and the TPTD group additionally received a daily subcutaneous injection of 20 μg TPTD for 6 months.

RESULTS

While 60.0% of the non-TPTD group showed one stage of improvement in BRONJ, 40.0% of the group did not show any improvement in disease status. In the TPTD group, 62.5% of the treated subjects showed one stage of improvement and the other 37.5% demonstrated a marked improvement, including two stages of improvement or complete healing, and there was not a single case that did not improve. The clinical improvement of BRONJ was statistically better in the TPTD group after the 6-month treatment (p < 0.05). Moreover, patients with higher baseline serum 25(OH)D levels showed better clinical therapeutic outcomes with TPTD.

CONCLUSIONS

We observed the beneficial effects of TPTD on BRONJ, and subjects with optimal serum vitamin D concentrations seemed to reap the maximum therapeutic effects of TPTD. A prospective, randomized, controlled trial should be needed to further evaluate the therapeutic efficacy of TPTD in the resolution of BRONJ.

Management strategy for small duodenal carcinoid tumors: does conservative management with close follow-up represent an alternative to endoscopic treatment?

BACKGROUND/AIMS

Limited data exist regarding the natural history of duodenal carcinoid tumors and the efficacy of endoscopic treatment.

METHODS

A total of 27 patients with duodenal carcinoid tumors were enrolled. All tumors were located outside the periampullary region and were ≤10 mm in size. 11 patients underwent endoscopic mucosal resection (EMR) and argon plasma coagulation (APC). 13 patients did not undergo any specific procedure for tumor removal and were followed clinically.

RESULTS

Of 13 patients not undergoing treatment, tumors disappeared in 5 cases during follow-up with diagnostic forceps biopsy. Endoscopically visible lesions remained in the last follow-up endoscopy in 8 patients (61.5%). No lymph node or distant metastases or tumor-related deaths occurred during a median follow-up of 37 months. Of 11 cases treated with EMR, tumor-free resection margins were achieved in 10 cases and no local recurrence occurred after treatment. Two perforations occurred during EMR. Of the 3 cases treated with APC, local recurrence occurred in 1 case.

CONCLUSIONS

Given the risks associated with EMR and the likely favorable natural history of small duodenal carcinoid tumors, conservative management with close follow-up may represent a viable alternative to endoscopic treatment, especially in patients with a high risk of perioperative complications.

Nanostring-based multigene assay to predict recurrence for gastric cancer patients after surgery

Despite the benefits from adjuvant chemotherapy or chemoradiotherapy, approximately one-third of stage II gastric cancer (GC) patients developed recurrences. The aim of this study was to develop and validate a prognostic algorithm for gastric cancer (GCPS) that can robustly identify high-risk group for recurrence among stage II patients. A multi-step gene expression profiling study was conducted. First, a microarray gene expression profiling of archived paraffin-embedded tumor blocks was used to identify candidate prognostic genes (N=432). Second, a focused gene expression assay including prognostic genes was used to develop a robust clinical assay (GCPS) in stage II patients from the same cohort (N=186). Third, a predefined cut off for the GCPS was validated using an independent stage II cohort (N=216). The GCPS was validated in another set with stage II GC who underwent surgery without adjuvant treatment (N=300). GCPS was developed by summing the product of Cox regression coefficients and normalized expression levels of 8 genes (LAMP5, CDC25B, CDK1, CLIP4, LTB4R2, MATN3, NOX4, TFDP1). A prospectively defined cut-point for GCPS classified 22.7% of validation cohort treated with chemoradiotherapy (N=216) as high-risk group with 5-year recurrence rate of 58.6% compared to 85.4% in the low risk group (hazard ratio for recurrence=3.16, p=0.00004). GCPS also identified high-risk group among stage II patients treated with surgery only (hazard ratio=1.77, p=0.0053).

Poorly differentiated component in gastric pinch biopsies predicts submucosal invasion

Background

Endoscopic resection has become standard therapy for selected patients with early gastric carcinoma (EGC). However, the preoperative diagnostic accuracy for excluding submucosal (SM) invasion is not precise. Moreover, histologic features predicting SM invasion in gastric carcinomas (SMiGC) have not been studied extensively.

Methods

Pre-treatment gastric biopsies from 60 patients with SM invasion who underwent endoscopic resection were reviewed and compared to 58 biopsies of lesions confirmed to be intramucosal carcinomas (IMC). For validation of the results, an independent cohort consisting of 616 gastric biopsies confirmed as EGC were analyzed. For statistical analyses, χ-square test, Fisher’s exact test and multiple logistic progression tests were used.

Results

In the biopsy specimens of patients with SMiGCs, differentiated histology, poorly differentiated component, wisps of muscularis mucosa, tumor cribriforming, papillary architecture, desmoplasia and intraglandular eosinophilic necrotic debris (IEND) were observed in 96.7%, 36.7%, 16.7%, 16.7%, 23.3%, 40%, and 46.7% of cases, respectively, while the same features were observed in 100%, 5.2%, 0%, 1.7%, 5.2%, 19%, and 22.4% of biopsies with IMC. In multivariate analyses, poorly differentiated component [odds ratio (OR), 9.59, p = 0.002], IEND [OR, 6.23, p = 0.012], tumor cribriforming [OR, 4.66, p = 0.03] and papillary architecture [OR, 5.52, p = 0.018] were significantly associated with the detection of SM invasion. In the validation cohort, poorly differentiated component (p = 0.003) and papillary architecture (p = 0.008) remained significant.

Conclusion

Poorly differentiated component and papillary architecture are significant histopathologic predictors of SM invasion in pretreatment gastric biopsies of lesions considered for endoscopic therapy. Additional prospective studies are warranted to confirm our findings.

Virtual slide

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1588557731103084

Epstein-Barr virus-associated lymphoepithelioma-like early gastric carcinomas and endoscopic submucosal dissection: Case series

Epstein-Barr virus (EBV)-associated lymphoepithelioma-like gastric carcinoma (LELC) is characterized by a lower lymph node (LN) metastasis rate and a higher survival rate than other forms of gastric cancer. Although current prognosis for LELC is favorable, the most common approach is radical gastrectomy involving an extensive D2 lymph node dissection. Here, we report four cases of EBV-associated early LELC that were treated by an alternative approach, endoscopic submucosal dissection (ESD). The long-term outcome of this procedure is discussed. All patients were treated by ESD en bloc, and all ESD specimens showed tumor-free lateral resection margins. None of the lesions showed lymphovascular invasion. A pathological examination of ESD specimens revealed submucosal invasion of more than 500 μm in all four cases. One patient underwent additional radical surgery post-ESD; no residual tumor or LN metastasis was noted in the surgical specimen. The other three patients did not undergo additional surgery, either because of severe comorbidity or their refusal to undergo operation, but were subjected to medical follow-up. None of the ESD-treated patients reported local recurrence or distant metastases during the 27-32 mo of follow-up after ESD.

Improved survival of gastric cancer with tumour Epstein-Barr virus positivity: an international pooled analysis

BACKGROUND AND OBJECTIVE

About 9% of gastric carcinomas have Epstein-Barr virus (EBV) in the tumour cells, but it is unclear whether viral presence influences clinical progression. We therefore examined a large multicentre case series for the association of tumour EBV status with survival after gastric cancer diagnosis, accounting for surgical stage and other prognostic factors.

METHODS

We combined individual-level data on 4599 gastric cancer patients diagnosed between 1976 and 2010 from 13 studies in Asia (n=8), Europe (n=3), and Latin America (n=2). EBV positivity of tumours was assessed by in situ hybridisation. Mortality HRs for EBV positivity were estimated by Cox regression models stratified by study, adjusted for distributions of sex (71% male), age (mean 58 years), stage (52% tumour-node-metastasis stages III or IV), tumour histology (49% poorly differentiated, 57% Lauren intestinal-type), anatomic subsite (70% non-cardia) and year of diagnosis. Variations by study and continent were assessed using study-specific HRs for EBV positivity.

RESULTS

During median 3.0 years follow-up, 49% of patients died. Stage was strongly predictive of mortality, with unadjusted HRs (vs stage I) of 3.1 for stage II, 8.1 for stage III and 13.2 for stage IV. Tumour EBV positivity was 8.2% overall and inversely associated with stage (adjusted OR: 0.79 per unit change). Adjusted for stage and other confounders, EBV positivity was associated with lower mortality (HR, 0.72; 95% CI 0.61 to 0.86), with low heterogeneity among the study populations (p=0.2). The association did not significantly vary across patient or tumour characteristics. There was no significant variation among the three continent-specific HRs (p=0.4).

CONCLUSIONS

Our findings suggest that tumour EBV positivity is an additional prognostic indicator in gastric cancer. Further studies are warranted to identify the mechanisms underlying this protective association.

Comparison of mixed venous oxygen saturation after in vitro calibration of pulmonary artery catheter with that of pulmonary arterial blood in patients undergoing living donor liver transplantation

INTRODUCTION

Mixed venous saturation (SvO2) reflects the balance between oxygen delivery and consumption throughout the body. A multifunction pulmonary artery catheter (PAC) can monitor continuous SvO2 after in vitro calibration (CSvO2), obviating the need for in vivo calibration with pulmonary arterial blood. In critically ill patients CSvO2 has shown a good correlation with measured SvO2 of pulmonary arterial blood using co-oximetry (MSvO2). The aim of this study was to compare CSvO2 and MSvO2 in liver transplantation (OLT) recipients.

METHODS

We enrolled 44 OLT recipients for comparison with 24 coronary artery bypass graft (CABG) controls free of end-stage liver disease. After anesthetic induction, the PAC was inserted after in vitro calibration and CSvO2 and MSvO2 simultaneously measured. In OLT recipients, additional measurements of CSvO2 and MSvO2 were performed at anhepatic and postreperfusion phases. Pearson's correlation analysis was used to evaluate the correlation between the 2 measurements. A Bland-Altman analysis was used to determine precision of and bias between the 2 measurements. With ±3% regarded to be interchangeable.

RESULTS

Cardiac output and intrapulmonary shunt in CABG patients were lower than among OLT recipients. OLT recipients, showed a significant correlation between CSvO2 and MSvO2, but the coefficients were different during the three phases of OLT (r = 0.597, 0.753, and 0.756). In addition, bias values between the two measurements were 6.0%, 6.4%, and 2.9% for the preanhepatic, anhepatic, and postreperfusion phases, respectively, with 29.5%, 31.8%, and 50% of them being interchangeable. In contrast CABG patients showed bias in -0.17% with 75% of measurements interchangeable.

CONCLUSION

While in vitro calibration of the PAC can be used in CABG patients, MSvO2 is higher than CSvO2 in OLT recipients. Therefore, in vivo calibration with pulmonary arterial blood is necessary for accurate monitoring of SvO2 in OLT recipients.

Abstract A02: Targeted deep sequencing of second biopsy tissues from patients with acquired resistance (AR) to EGFR tyrosine kinase inhibitors harboring EGFR mutations: Preliminary results

Background: Patients with EGFR activating mutation in non-small cell lung cancer (NSCLC) eventually develop AR to EGFR tyrosine kinase inhibitors (TKI) after durable and high response. Several mechanisms of AR to EGFR TKIs identified include T790M gatekeeper mutation, PIK3CA mutation, C-met amplification, transformation into small cell carcinoma or epithelial-mesenchymal transition (EMT). In the present study, to identify other genetic alterations, we performed targeted deep sequencing for over 700 hotspots in 50 cancer-related genes using next generation sequencing (NGS) technology.

Methods: Genomic DNA was extracted from FFPE tissue or pleural/pericardial fluid or primary culture cells of 57 NSCLC patients who developed AR to EGFR TKIs. Amplicons NGS libraries for 50 oncogenes included in Ion AmpliSeqTM Cancer Hotspot Panel v.2 were generated and sequenced in the Ion PGM Sequencer. Variant caller included in Torrent Suite Software was utilized to identify mutations in the samples, annotation was performed with IonTorrentTM Software.

Results: All 57 patients were treated with EGFR TKIs, gefitinib (n=39), erlotinib (n=17), or afatinib (n=1) as first-line or later line of therapy. 65% were female, 74% never smokers, median age of 58 years (range 25-77) and 98% were adenocarcinoma. 31 patients have exon 19 deletion and 14 with L858R at baseline. The median PFS for EGFR TKIs was 11 months (range 4-63). Targeted deep sequencing of second biopsy identified recurrent coexisting mutations of T790M in 52.6%. Other frequently altered genes include mutation of CTNNB1 (n=9), c-KIT (n=7), c-met (n=7), SMARCB1 (n=5), PDGFRA (n=5), PTEN (n=2), NRAS (n=2), and PIK3CA (n=1). However, in order to investigate whether these recurrent mutations observed in second biopsy represent genes associated with AR or pre-existing genes, targeted deep sequencing of available paired baseline samples will be performed and updated.

Conclusions: We found that NGS technology is feasible in FFPE tissues. Although T790M mutation confers the most common resistant mechanism to EGFR TKI, several detected genetic mutations are novel observations which might provide potential candidates for AR mechanisms. Further validation results will be discussed.

Citation Format: Myung-Ju Ahn, Youngwook Kim, Kyoung-Mee Kim, Yoon-la Choi, Joungho Han, EunHye Jho, Joung-Mu Sun, Jin-Sock Ahn, Keunchil Park. Targeted deep sequencing of second biopsy tissues from patients with acquired resistance (AR) to EGFR tyrosine kinase inhibitors harboring EGFR mutations: Preliminary results. [abstract]. In: Proceedings of the AACR-IASLC Joint Conference on Molecular Origins of Lung Cancer; 2014 Jan 6-9; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2014;20(2Suppl):Abstract nr A02.

Exome sequencing identifies early gastric carcinoma as an early stage of advanced gastric cancer

Gastric carcinoma is one of the major causes of cancer-related mortality worldwide. Early detection and treatment leads to an excellent prognosis in patients with early gastric cancer (EGC), whereas the prognosis of patients with advanced gastric cancer (AGC) remains poor. It is unclear whether EGCs and AGCs are distinct entities or whether EGCs are the beginning stages of AGCs. We performed whole exome sequencing of four samples from patients with EGC and compared the results with those from AGCs. In both EGCs and AGCs, a total of 268 genes were commonly mutated and independent mutations were additionally found in EGCs (516 genes) and AGCs (3104 genes). A higher frequency of C>G transitions was observed in intestinal-type compared to diffuse-type carcinomas (P = 0.010). The DYRK3, GPR116, MCM10, PCDH17, PCDHB1, RDH5 and UNC5C genes are recurrently mutated in EGCs and may be involved in early carcinogenesis.

CD151 overexpression is associated with poor prognosis in patients with pT3 gastric cancer

INTRODUCTION

CD151, a transmembrane protein of the tetraspanin family, is implicated in the regulation of cell-substrate adhesion and cell migration. Overexpression of CD151 has been reported in several cancers and controls MET-dependent neoplastic growth by enhancing receptor signaling. However, association of CD151 overexpression with MET or tumor progression has not been reported in gastric cancer.

MATERIALS AND METHODS

We conducted immunohistochemical analysis of CD151 overexpression in 491 pT3 gastric carcinomas and analyzed the relationship with MET overexpression and prognostic significance.

RESULTS

CD151 was highly expressed in 119 gastric carcinomas (24.2 %) and was significantly associated with higher pN stages. Patients with CD151-positive gastric cancer showed shorter overall (p = 0.003) and disease-free survival (p = 0.001) compared with patients with CD151-negative gastric carcinoma. CD151 overexpression was an independent prognostic factor for overall survival [hazard ration (HR) 1.335; 95 % CI 1.005-1.775; p = 0.046] and disease-free survival (HR 1.903; 95 % CI 1.348-2.685; p < 0.001). Co-overexpression of CD151 and MET was observed in 30 (6.1 %) gastric cancers and was more frequent in advanced pN stages than in other groups. Moreover, co-overexpression of CD151 and MET was a strong independent prognostic factor for overall survival (HR 3.163; 95 % CI 1.958-5.108; p < 0.001) and disease-free survival (HR 3.834; 95 % CI 2.145-6.852; p < 0.001).

CONCLUSION

CD151 overexpression is an independent prognostic factor and could be a potential molecular therapeutic target in patients with advanced gastric cancers. Further studies are needed to establish the biological significance of CD151/MET co-overexpression and the potential of targeting both molecules as a therapeutic strategy.

MET overexpression assessed by new interpretation method predicts gene amplification and poor survival in advanced gastric carcinomas

The establishment of better selection criteria for identifying sub-populations that may benefit from treatment is a key aspect of the development and success of targeted therapy. To investigate methods for assessing MET overexpression in gastric cancer, we conducted immunohistochemistry using a new anti-Total MET monoclonal antibody in a single-institution cohort of 495 patients. As antibody is directed against a membranous and/or cytoplasmic epitope, two interpretation methods were used: (1) membranous and cytoplasmic and (2) membranous alone. In selected 120 cases, copy number gain and mRNA expression levels were measured using quantitative real-time PCR. Further in situ hybridization confirmed the presence of MET gene amplification. Among the 495 gastric cancers, simultaneous membranous and cytoplasmic overexpression of MET was found in 108 cases (21.8%) and membranous alone overexpression was observed in 40 cases (8.1%). The highest correlation was observed in membranous and cytoplasmic staining of MET: MET expression scores correlated significantly with high MET mRNA levels (r=0.465, P<0.0001), increased copy number gain (r=0.393, P=0.000002) and amplification of MET gene. Moreover, patients with MET overexpression showed shorter overall survival (HR, 1.781; 95% CI, 1.324-2.395; P<0.001) and disease-free survival (HR, 1.765; 95% CI, 1.227-2.541; P=0.002) compared with patients without MET overexpression. However, membranous overexpression of MET did not highly correlate with mRNA level (r=0.274, P=0.002), copy number gain or survival (P>0.05). We developed highly correlating interpretation methods of MET immunohistochemistry in gastric carcinomas. MET overexpression is an independent prognostic factor and could be a potential target and predictor of benefit for targeted therapy with MET inhibitors.

GSTT1 copy number gain and ZNF overexpression are predictors of poor response to imatinib in gastrointestinal stromal tumors

Oncogenic mutations in gastrointestinal stromal tumors (GISTs) predict prognosis and therapeutic responses to imatinib. In wild-type GISTs, the tumor-initiating events are still unknown, and wild-type GISTs are resistant to imatinib therapy. We performed an association study between copy number alterations (CNAs) identified from array CGH and gene expression analyses results for four wild-type GISTs and an imatinib-resistant PDGFRA D842V mutant GIST, and compared the results to those obtained from 27 GISTs with KIT mutations. All wild-type GISTs had multiple CNAs, and CNAs in 1p and 22q that harbor the SDHB and GSTT1 genes, respectively, correlated well with expression levels of these genes. mRNA expression levels of all SDH gene subunits were significantly lower (P≤0.041), whereas mRNA expression levels of VEGF (P=0.025), IGF1R (P=0.026), and ZNFs (P<0.05) were significantly higher in GISTs with wild-type/PDGFRA D842V mutations than GISTs with KIT mutations. qRT-PCR validation of the GSTT1 results in this cohort and 11 additional malignant GISTs showed a significant increase in the frequency of GSTT1 CN gain and increased mRNA expression of GSTT1 in wild-type/PDGFRA D842V GISTs than KIT-mutant GISTs (P=0.033). Surprisingly, all four malignant GISTs with KIT exon 11 deletion mutations with primary resistance to imatinib had an increased GSTT1 CN and mRNA expression level of GSTT1. Increased mRNA expression of GSTT1 and ZNF could be predictors of a poor response to imatinib. Our integrative approach reveals that for patients with wild-type (or imatinib-resistant) GISTs, attempts to target VEGFRs and IGF1R may be reasonable options.

Clinical outcomes of radiation therapy for early-stage gastric mucosa-associated lymphoid tissue lymphoma

AIM: To evaluate the clinical outcomes of radiation therapy (RT) for early-stage gastric mucosa-associated lymphoid tissue lymphoma (MALToma).

METHODS: The records of 64 patients treated between 1998 and 2011 were analyzed retrospectively. For Helicobacter pylori (H. pylori)-positive patients (n = 31), chemotherapy or H. pylori eradication therapy was the initial treatment. In patients with failure after H. pylori eradication, RT was performed. For H. pylori-negative patients (n = 33), chemotherapy or RT was the first-line treatment. The median RT dose was 36 Gy. The target volume included the entire stomach and the perigastric lymph node area.

RESULTS: All of the patients completed RT without interruption and showed complete remission on endoscopic biopsy after treatment. Over a median follow-up period of 39 mo, the 5-year local control rate was 89%. Salvage therapy was successful in all relapsed patients. Secondary malignancies developed in three patients. The 5-year overall survival rate was 94%. No patient presented symptoms of moderate-to-severe treatment-related toxicities during or after RT.

CONCLUSION: Radiotherapy results in favorable clinical outcomes in patients with early-stage gastric MALToma who experience failure of H. pylori eradication therapy and those who are H. pylori negative.

Phase II trial of capecitabine and everolimus (RAD001) combination in refractory gastric cancer patients

BACKGROUND

The aim of this study was to assess the efficacy and safety of combination regimen of capecitabine plus everolimus in patients with refractory gastric cancer who have failed to at least two cytotoxic regimens.

METHODS

Patients received capecitabine 650 mg/m(2) twice daily (D1-14) and everolimus 5 mg twice daily (D1-21) every 3 weeks until disease progression or unacceptable toxicity. The primary endpoint of the study was overall response (partial or complete response) and the secondary endpoints were progression-free survival (time between registration and disease progression or death) and overall survival. Pharmacokinetic analysis was also performed. Patients who have failed to at least two cytotoxic regimens were enrolled.

RESULTS

Between March 2010 and June 2012, 47 patients were enrolled. 33 patients (70.2%) had received more than three previous regimens prior to enrolment. Among 43 evaluable patients for treatment response, 5 patients achieved confirmed partial response and 18 patients showed stable disease, resulting in an overall response rate (ORR) of 10.6% (95% C.I.: 1.8-19.4%) and disease control rate of 48.9% (95% C.I.:34.6-63.2%). At a median follow-up of 106 weeks (range, 21-141 weeks), the median progression-free survival and overall survival were 11.0 weeks (95% C.I.: 5.7-16.3 weeks) and 21.0 weeks (95% C.I.: 14.3-27.7 weeks), respectively. Grade 3 nausea, diarrhea and stomatitis occurred in two, three and three patients, respectively. Elevated liver enzyme was observed in 21 patients and no patient had pulmonary fibrosis.

CONCLUSIONS

The combination of capecitabine 650 mg/m(2) twice daily and everolimus 5 mg twice daily was found to be effective in a small subset of GC patients who were heavily pre-treated.

Comparison of Three BRAF Mutation Tests in Formalin-Fixed Paraffin Embedded Clinical Samples

BACKGROUND

Recently, BRAF inhibitors showed dramatic treatment outcomes in BRAF V600 mutant melanoma. Therefore, the accuracy of BRAF mutation test is critical.

METHODS

BRAF mutations were tested by dual-priming oligonucleotide-polymerase chain reaction (DPO-PCR), direct sequencing and subsequently retested with a real-time PCR assay, cobas 4800 V600 mutation test. In total, 64 tumors including 34 malignant melanomas and 16 papillary thyroid carcinomas were analyzed. DNA was extracted from formalin-fixed paraffin embedded tissue samples and the results of cobas test were directly compared with those of DPO-PCR and direct sequencing.

RESULTS

BRAF mutations were found in 23 of 64 (35.9%) tumors. There was 9.4% discordance among 3 methods. Out of 6 discordant cases, 4 cases were melanomas; 3 cases were BRAF V600E detected only by cobas test, but were not detected by DPO-PCR and direct sequencing. One melanoma patient with BRAF mutation detected only by cobas test has been on vemurafenib treatment for 6 months and showed a dramatic response to vemurafenib. DPO-PCR failed to detect V600K mutation in one case identified by both direct sequencing and cobas test.

CONCLUSIONS

In direct comparison of the currently available DPO-PCR, direct sequencing and real-time cobas test for BRAF mutation, real-time PCR assay is the most sensitive method.

High proportion of granzyme B+ intraepithelial lymphocytes contributes to epithelial apoptosis in Helicobacter pylori-associated lymphocytic gastritis

BACKGROUND

Helicobacter pylori infection has been linked to the development of lymphocytic gastritis (LG) characterized by ≥25 intraepithelial lymphocytes (IELs) per 100 epithelial cells. We hypothesize that the changes in the subpopulation and/or cytotoxicity of IELs leading to epithelial cell apoptosis may be involved in the pathogenesis of H. pylori-associated LG.

MATERIALS AND METHODS

We examined IEL subpopulations and the expression of cytotoxic molecules by IELs in biopsy specimens from 36 patients with H. pylori-associated LG by immunostainings for CD3, CD4, CD8, T-cell-restricted intracellular antigen-1 (TIA-1), and granzyme B (GrB) and compared the results with those obtained from 49 patients with H. pylori-associated gastritis (HPG). To investigate whether the IEL-mediated cytotoxicity is related to the increase of epithelial apoptosis, we performed a terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay using ApopTag detection kit.

RESULTS

Between LG and HPG groups, significant differences in the number of CD3+, CD4+, CD8+, TIA-1+ or GrB+ IELs, and ApopTag indices were found. Among the CD3+ IELs, the proportion of CD8+ IELs or TIA-1+ IELs did not differ between two groups. The LG group showed a selective increase in GrB-positive, phenotypically activated IELs, which was paralleled by an increase in ApopTag indices. In contrast, the HPG group showed more heterogeneous IEL subpopulations with more CD4+ IELs and less GrB+ IELs compared with the LG group, and we did not find any significant variable contributing to the epithelial apoptosis in the HPG group.

CONCLUSIONS

This study shows that in addition to the numerical increase in the IELs, there are significant changes in the subpopulations and cytotoxicity of IELs between HPG and H. pylori-associated LG. In particular, enhanced GrB-associated cytotoxicity of the IELs in H. pylori-associated LG contributes to an increase in epithelial apoptosis.