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

Radiomics-based assessment of HER2 status and prognosis in gastric cancer: a retrospective dual-center CT study

PURPOSE

This research investigated the potential of CT-based radiomics analysis for predicting human epidermal growth factor receptor 2 (HER2) status and assessing the prognosis of patients with gastric cancer (GC).

METHODS

431 patients with GC from two medical centers were included in this retrospective study, with patients allocated to a training cohort (n = 221), a testing cohort (n = 94), and an external validation cohort (n = 116). Radiomics features and clinical variables associated with HER2 status were identified, and the radiomics score was subsequently derived. A radiomics model was constructed using the radiomics score, and a nomogram was developed by integrating related variables. The predictive accuracy of models was assessed via receiver operating characteristic curves, with the area under the curve (AUC) being computed. Prognostic significance was assessed by exploring the association between nomogram-predicted HER2 status and overall survival (OS).

RESULTS

The radiomics model yielded AUCs of 0.801, 0.793, and 0.784 for the training, testing, and external validation cohorts, respectively. A nomogram that integrated sex, CA72-4 levels, and radiomics score exhibited enhanced predictive accuracy, achieving AUCs of 0.847, 0.836, and 0.828 across the cohorts. Decision curve analysis highlighted the clinical utility of the nomogram, illustrating its ability to deliver a higher net benefit. In addition, survival analysis indicated that individuals with nomogram-predicted HER2 positivity experienced significantly shorter OS, providing robust risk stratification and prognostic insights.

CONCLUSION

The CT-based radiomics nomogram demonstrated the ability to non-invasively predict preoperative HER2 status and stratify prognostic risk in this GC cohort.

Spatial and Temporal Tumor Heterogeneity in Gastric Cancer: Discordance of Predictive Biomarkers

Gastric cancer (GC) is a highly heterogeneous disease that varies in both histological presentation and genetic characteristics. Recent advances in the treatment of metastatic and unresectable GC have made several biomarker tests essential for patient management. Predictive biomarkers such as human epidermal growth factor receptor 2 (HER2), programmed death-ligand 1 (PD-L1), mismatch-repair (MMR) proteins, claudin 18.2, and fibroblast growth factor receptor 2b (FGFR2b) are commonly evaluated using immunohistochemistry. However, the expression levels of these biomarkers may vary across different tumor areas, and the accuracy of biomarker diagnosis can be affected by sample quantity, sample location, and collection method. Therefore, tumor heterogeneity presents substantial challenges for accurate biomarker-based diagnosis and prediction of therapeutic responses. Tumor heterogeneity can be categorized into spatial heterogeneity, which refers to variations within the primary tumor (intra-tumoral) or between primary and metastatic sites, and temporal heterogeneity, which encompasses changes over time. This review addresses the tumor heterogeneity in predictive biomarker expression in GC, focusing on HER2, PD-L1, MMR, the Epstein-Barr virus, claudin 18.2, and FGFR2b.

HER2-targeted therapies beyond breast cancer - an update

The receptor tyrosine-kinase HER2 (also known as ErbB2) is a well-established therapeutic target in patients with breast or gastric cancer selected on the basis of HER2 overexpression on immunohistochemistry and/or ERBB2 amplification on in situ hybridization. With advances in cancer molecular profiling and increased implementation of precision medicine approaches into oncology practice, actionable HER2 alterations in solid tumours have expanded to include ERBB2 mutations in addition to traditional HER2 overexpression and ERBB2 amplification. These various HER2 alterations can be found in solid tumour types beyond breast and gastric cancer, although few HER2-targeted therapeutic options have been established for the other tumour types. Nevertheless, during the 5 years since our previous Review on this topic was published in this journal, obvious and fruitful progress in the development of HER2-targeted therapies has been made, including new disease indications, innovative drugs with diverse mechanisms of action and novel frameworks for approval by regulatory authorities. These advances have culminated in the recent histology-agnostic approval of the anti-HER2 antibody-drug conjugate trastuzumab deruxtecan for patients with HER2-overexpressing solid tumours. In this new Review, we provide an update on the current development landscape of HER2-targeted therapies beyond breast cancer, as well as anticipated future HER2-directed treatment strategies to overcome resistance and thereby improve efficacy and patient outcomes.

Clinicopathological analysis of CD47 and signal regulatory protein alpha expression in myeloid sarcoma patients: CD47 expression is a favourable prognostic factor

Myeloid sarcoma is a rare extramedullary haematopoietic malignancy. Interaction between CD47 and signal regulatory protein α (SIRPα) inhibits phagocytosis. CD47-positive tumours confer poor prognoses in various malignant tumours, including acute myeloid leukaemia. This study aimed to investigate the clinicopathological effects of CD47 and SIRPα expression in myeloid sarcoma. Immunohistochemistry (IHC) of CD47 and SIRPα was performed in 84 biopsy samples obtained from patients with myeloid sarcoma, some of which were CD47-positive. Patients were categorised into the following two groups based on IHC of SIRPα: those with SIRPα-positive neoplastic cells (nSIRPα) and, SIRPα expression on non-neoplastic stromal cells in tumour microenvironment (miSIRPα). In addition, patients with CD47 positivity had higher lymphocytic infiltration into the tumour microenvironment. Overall, these patients had significantly higher overall survival, however, no significant difference was observed in progression-free survival. No significant prognostic differences were observed between the nSIRPα and miSIRPα groups. This is the first study to demonstrate an association between CD47 expression and improved prognosis in myeloid sarcoma. Nonetheless, it will be necessary to conduct additional research on gene expression and genomic abnormalities to elucidate the corresponding pathogenesis of myeloid sarcoma.

Human epidermal growth factor receptor-2 gene expression positivity determined by silver in situ hybridization/immunohistochemistry methods and associated factors in a cohort of Sri Lankan patients with gastric adenocarcinoma: a prospective study

OBJECTIVE

Positive human epidermal growth factor 2 (HER2) expression and its predictive clinicopathological features remain unclear in Sri Lankan gastric cancer (GC) patients. Here, we aimed to determine GC HER2 status predictors by analyzing associations between clinicopathological features and HER2 expression using immunohistochemistry (IHC) and silver in situ hybridization (SISH).

METHODS

During this 4-year prospective study, clinicopathological data were collected from participants in the National Hospital of Sri Lanka. HER2 IHC and SISH were performed using commercial reagents. Using chi-square tests, associations of HER2-IHC/SISH with clinicopathological features were analyzed.

RESULTS

Overall, 145 GC patients were included, 69 had gastrectomies and 76 had biopsies. Positive HER2 expression by IHC was associated with age <60 years, high T stage (assessed pathologically in resections and radiologically in biopsies), high nuclear grade, tumor necrosis, mitosis >5/high-power field, with additional perineural invasion and lymphovascular invasion in resections. These features, excluding lymphovascular invasion but including male sex, were associated with HER2 expression by SISH.

CONCLUSIONS

Age <60 years, high nuclear grade, tumor necrosis, and perineural invasion are associated factors of HER2 status. These could be used to triage GC patients for HER2 status testing in limited resource settings where IHC/SISH analysis is costly.

Dual block HER2 assessment increased HER2 immunohistochemistry positive rate in resected specimens of gastric cancer: a prospective multicenter clinical trial from China

Background

Former single center studies indicated that HER2 assessment with two primary tumor blocks (dual block HER2 assessment) could be an efficient and practical approach to overcome the adverse impact of heterogeneity and acquire a HER2 positive rate in gastric cancer (GC). This multicenter prospective clinical trial (NCT 02843412) was launched to verify its value and generality.

Methods

A total of 3806 participants with primary GCs have been enrolled from 8 hospitals in China. Two primary tumor blocks were selected and recorded as block 1 and block 2 after histological evaluation. An HER2 (4B5) rabbit monoclonal antibody was used for the immunohistochemistry (IHC) analysis.

Results

In total patients, HER2 IHC positive (3+) rate with dual block assessment (9.4%) was higher than that with single block assessment (block 1: 7.8%, block 2: 7.8%) (P < 0.001). Compared with single-block assessment, dual-block assessment increased the positive rate by approximate 20%. Similarly, HER2 equivocal (2+) rate was increased in dual block assessment (25.8%), which was higher than that in single block assessment (block 1: 20.3%, block 2: 20.9%) (P < 0.001). Conversely, dual block assessment demonstrated a lower HER2 negative (0/1+) rate (64.8%) than single block assessment (block1: 71.9%, block 2: 71.3%) (P < 0.001). These findings were also confirmed in individual hospitals.

Conclusions

Dual block HER2 assessment effectively increased HER2 IHC positive rate in resected specimens of GC. We recommended dual block HER2 assessment be promoted in routine clinical practice in GC.

Trial registration

ClinicalTrials.gov, NCT 02843412. Registered 1 July 2016 - Retrospectively registered.

Caveolin-1 temporal modulation enhances antibody drug efficacy in heterogeneous gastric cancer

Resistance mechanisms and heterogeneity in HER2-positive gastric cancers (GC) limit Trastuzumab benefit in 32% of patients, and other targeted therapies have failed in clinical trials. Using patient samples, patient-derived xenografts (PDXs), partially humanized biological models, and HER2-targeted imaging technologies we demonstrate the role of caveolin-1 (CAV1) as a complementary biomarker in GC selection for Trastuzumab therapy. In retrospective analyses of samples from patients enrolled on Trastuzumab trials, the CAV1-high profile associates with low membrane HER2 density and low patient survival. We show a negative correlation between CAV1 tumoral protein levels – a major protein of cholesterol-rich membrane domains – and Trastuzumab-drug conjugate TDM1 tumor uptake. Finally, CAV1 depletion using knockdown or pharmacologic approaches (statins) increases antibody drug efficacy in tumors with incomplete HER2 membranous reactivity. In support of these findings, background statin use in patients associates with enhanced antibody efficacy. Together, this work provides preclinical justification and clinical evidence that require prospective investigation of antibody drugs combined with statins to delay drug resistance in tumors.

Clinical evidences have demonstrated limited efficacy of HER2-targeted therapies in patients with gastric cancer (GC). Here the authors show that survival benefit to anti-HER2 antibody Trastuzumab is reduced in GC patients with high levels of the caveolin-1 and that, in preclinical cancer models, antibody drug efficacy can be improved by modulating caveolin-1 levels with cholesterol-depleting drugs, statins.

Pre-Clinical Study of the [18F]AlF-Labeled HER2 Affibody for Non-Invasive HER2 Detection in Gastric Cancer

Human epidermal growth factor receptor 2 (HER2) is an important biomarker in gastric cancer (GC) and directly influences the therapeutic effect. Fluorine is firmly bound to Al³⁺ forming [¹⁸F]AlF-1,4,7-triazacyclononanetriacetic acid (NOTA)-HER2 affibody is a promising radiolabeled tracer that can monitor the changes of HER2 expression combining the advantages of simple preparation and the properties of ¹⁸F. The aim of this study was to develop a quick method for the synthesis of [¹⁸F]AlF-NOTA-HER2 affibody and evaluate its utility for HER2+ GC imaging in mouse models. Moreover, ⁶⁸Ga-NOTA-HER2 affibody imaging was also performed to highlight the superiority of [¹⁸F]AlF-NOTA-HER2 affibody imaging in resolution. The HER2 affibody was conjugated with NOTA and labeled using ¹⁸F based on the complexation of [¹⁸F]AlF by NOTA. Its quality control and stability were performed by high-pressure liquid chromatography (HPLC). The molecular specificity and binding affinity of the novel radiotracer were evaluated in the GC cell line with HER2 overexpression (NCI-N87) and negative expression (MKN74). Distribution studies and PET/CT imaging were performed in mouse models. ⁶⁸Ga-NOTA-HER2 affibody PET/CT imaging was also performed. [¹⁸F]AlF-NOTA-HER2 affibody was efficiently prepared within 30 min with a non-decay-corrected maximum yield of 32.69% and a radiochemical purity of more than 98%. [¹⁸F]AlF-NOTA-HER2 affibody was highly stable in incubation medium for 4 h in vitro and in the blood of nude mice at 30 min post-injection (p.i.). In vitro studies revealed specific binding and high binding affinity of the probe in NCI-N87 cells, while no binding was seen in MKN74 cells. PET imaging showed that NCI-N87 xenografts were differentiated from MKN74 xenografts with excellent contrast and low abdominal background, which was confirmed by the distribution results. High-level accumulation of the [¹⁸F]AlF-NOTA-HER2 affibody in HER2+ tumors was blocked by excess unlabeled NOTA-HER2 affibody. [¹⁸F]AlF-NOTA-HER2 affibody has a higher image resolution than that of ⁶⁸Ga-NOTA-HER2 affibody. [¹⁸F]AlF-NOTA-HER2 affibody could be produced facilely with high radiochemical yield and may serve as a novel molecular probe with tremendous clinical potential for the non-invasive whole-body detection of the HER2 status in GC with good image contrast and resolution. This method could provide an in vivo understanding of GC biology that will ultimately guide the accurate diagnosis and treatment of GC.

Extremely well-differentiated adenocarcinoma of the stomach: diagnostic pitfalls in endoscopic biopsy

Background

Extremely well-differentiated adenocarcinoma (EWDA) is a deceptively bland-looking adenocarcinoma of the stomach. It often causes diagnostic problems, especially in endoscopic biopsy samples. To better recognize this deceptively bland lesion, we carefully reviewed a series of EWDAs treated at our institution.

Methods

A total of 55 specimens from 19 patients were obtained. Endoscopic, gross and microscopic features defining EWDA were described and documented. For comparison, hyperplastic polyp specimens were randomly selected and analyzed.

Results

Most cases (18 of 19, 94.7%) were advanced gastric cancer (AGC) and primarily located in the body of the stomach (15 of 19, 79.0%). The majority of AGCs were non-ulcerated (11 of 18, 61.1%) with an undermining growth pattern and a relatively small mucosal involvement. Specific histologic features included an irregular glandular shape, an undulating apical cytoplasmic border, disproportionately large glands, a variably distended mucinous cytoplasm. Classical features, such as small infiltrating glands or desmoplastic reactions, were barely observed. Identification of irregularly spaced nuclei and disruption of the foveolar epithelial structure, along with atypical features described above were helpful in making a diagnosis especially in gastric forceps biopsies.

Conclusions

Awareness of the histomorphologic characteristics described in this report would lead to timely diagnosis and prevent repeated endoscopic procedures.

HER2 promotes epithelial-mesenchymal transition through regulating osteopontin in gastric cancer

AIMS

HER2 and osteopontin (OPN) are both important biomarkers in gastric cancer (GC). The relationships between them remain to be revealed. The purpose of this study is to explore the role of OPN in epithelial-mesenchymal transition (EMT) in HER2 positive GCs.

METHODS

Nanostring analysis was used to compare the mRNA levels of 730 cancer related genes between paired HER2 3+ and non-3+ areas in GC patients. Immunohistochemistry (IHC) staining was performed to analyze the expression levels of OPN, as well as EMT markers including E-cad, N-cad, twist and vimentin in both areas. To further verify the role of OPN in EMT, the expression levels of OPN and EMT markers, tumor invasion/migration were analyzed after down-regulating HER2 and OPN in GC cell lines MKN-45 and N-87.

RESULTS

Nanostring analysis identified 8 differential expression genes between HER2 3+ and non-3+ areas. Among them, the expression level of OPN was positively correlated with that of HER2. In GC specimens, OPN showed higher expression level in HER2 3+ areas where higher E-cad expression levels and lower N-cad and twist levels were also found. After knocking down OPN and HER2 by siRNA, both cell lines show decreased invasion/migration abilities, along with the down-regulation of the EMT phenotype, supporting by the decrease of E-cad, and the increase of N-cad and twist at both mRNA and protein levels. In addition, HER2 knock-down lead to a dramatic decrease of OPN expression.

CONCLUSIONS

These findings indicate that HER2 may promote EMT via the regulation of OPN in GCs.

Genomic and transcriptomic profiling of hepatoid adenocarcinoma of the stomach

Hepatoid adenocarcinoma of the stomach (HAS), a rare subtype of gastric cancer (GC), has a low incidence but a high mortality rate. Little is known about the molecular features of HAS. Here we applied whole-exome sequencing (WES) on 58 tumours and the matched normal controls from 54 HAS patients, transcriptome sequencing on 30 HAS tumours, and single-cell RNA sequencing (scRNA-seq) on one HAS tumour. Our results reveal that the adenocarcinomatous component and hepatocellular-like component of the same HAS tumour originate monoclonally, and HAS is likely to initiate from pluripotent precursor cells. HAS has high stemness and high methionine cycle activity compared to classical GC. Two genes in the methionine cycle, MAT2A, and AHCY are potential targets for HAS treatments. We provide the first integrative genomic profiles of HAS, which may facilitate its diagnosis, prognosis, and treatment.

HER2-targeted therapies in gastric cancer

Molecular targeted therapy of cancer has always been the focus of clinicians. Among those therapeutic targets, the human epidermal growth factor receptor-2 (HER-2) signaling pathway is one of the most popular targets for translational research in cancer. However, unlike prospect in breast cancer, HER-2 inhibitor trastuzumab is the only molecular targeted drug approved by US Food and Drug Administration (FDA) for the first-line treatment of HER-2 positive advanced gastric cancer. On this basis, a variety of novel HER2- targeted drugs for gastric cancer are under development, and related clinical researches are in full swing, including small molecular kinase inhibitors (e.g., afatinib, neratinib, pyrotinib), antibody-drug conjugates (e.g., DS-8201a, RC48-ADC) and other novel therapies (e.g., ZW25, CAR-T, BVAC-B). In this study, we will summarize the recent advances in anti-HER-2 agents, potential mechanisms of resistance to HER2-targeted therapy in HER2-positive gastric cancer. We will also discuss the future prospects of potential strategies to overcome anti-HER-2 resistance and development of novel anti-HER-2 approaches for the treatment of HER2-positive gastric cancer patients.

Dual-Energy CT-Based Nomogram for Decoding HER2 Status in Patients With Gastric Cancer

OBJECTIVE. The purpose of this study was to develop and evaluate a dual-energy CT (DECT)-based nomogram for noninvasive identification of the status of human epidermal growth factor receptor 2 (HER2; also known as ERBB2) expression in gastric cancer (GC). MATERIALS AND METHODS. A total of 206 patients with histologically proven GC who underwent pretreatment DECT were retrospectively recruited and randomly allocated to a training cohort (n = 144) or a test cohort (n = 62). Information on clinical characteristics, qualitative imaging features, and quantitative DECT parameters was collected. Univariate analysis and multivariate logistic regression were implemented to screen independent predictors of HER2 status. An individualized nomogram was built, and its discrimination, calibration, and clinical usefulness were assessed. RESULTS. Tumor location, the iodine concentration of the tumor in the venous phase, and the normalized iodine concentration of the tumor in the venous phase were significant factors predictive of HER2 status (all p < .05). After these three indicators were integrated, the proposed nomogram showed a favorable diagnostic performance, with AUCs of 0.807 (95% CI, 0.718-0.897) in the training cohort and 0.815 (95% CI, 0.661-0.968) in the test cohort. The nomogram showed a preferable fitting (all p > .05 by the Hosmer-Lemeshow test) and would offer more net benefits than simple default strategies within a wide range of threshold probabilities in both cohorts. CONCLUSION. The DECT-based nomogram has great application potential in terms of detecting HER2 status in GC, and can serve as a novel substitute for invasive testing.

PYGB Promoted Tumor Progression by Regulating Wnt/β-Catenin Pathway in Gastric Cancer

Gastric cancer is one of the most common gastrointestinal malignancy with high mortality in East Asia. Investigation of pathogenic mechanisms of gastric cancer is crucial to develop novel therapeutic strategies and identify new therapeutic candidates. Brain-type glycogen phosphorylase is a glycogen phosphorylase involved in glycogen metabolism, which participates in multiple physiological and pathological processes. Overexpression of brain-type glycogen phosphorylase has been reported in various types of cancer, such as colorectal cancer and non-small cell lung cancer, however, the potential role of brain-type glycogen phosphorylase in gastric cancer remains unclear. Herein, we observed brain-type glycogen phosphorylase expression was significantly elevated in human gastric cancer tissues and positively correlated with the clinical-pathological features including tumor size, lymph node involvement, and tumor, node, metastasis stage of patients with gastric cancer. We further reported brain-type glycogen phosphorylase depletion suppressed the growth of gastric cancer, weakened the epithelial–mesenchymal transformation, and reduced the migration and invasion ability in cell models. We further confirmed brain-type glycogen phosphorylase depletion inhibited tumor growth and lung metastasis in mice. Importantly, we found brain-type glycogen phosphorylase regulated the progression of gastric cancer via Wnt/β-catenin pathway, shedding lights on brain-type glycogen phosphorylase as a promising therapeutic target for drug design and development targeting gastric cancer.

DNA-protein biomarkers for immunotherapy in the era of precision oncology

The use of biomarkers to guide patient and therapy selection has gained much attention to increase the scope and complexity of targeted therapy options and immunotherapy. Clinical trials provide a basis for discovery of biomarkers, which can then aid in development of new drugs. To that end, samples from cancer patients, including DNA, RNA, protein, and the metabolome isolated from cancer tissues and blood or urine, are analyzed in various ways to identify relevant biomarkers. In conjunction with nucleotide-based, high-throughput, next-generation sequencing techniques, therapy-guided biomarker assays relying on protein-based immunohistochemistry play a pivotal role in cancer care. In this review, we discuss the current knowledge regarding DNA and protein biomarkers for cancer immunotherapy.

Intratumoral and intertumoral heterogeneity of HER2 immunohistochemical expression in gastric cancer

BACKGROUND

Given the high heterogeneity of tumor tissue in gastric cancer (GC), inaccurate detection of tumor biomarkers will inevitably hamper a precise diagnosis and selection of patients for targeted therapies. Human epidermal growth factor receptor 2 (HER2) has been widely accepted as an underlying treatment biomarker of GC. The objective of this study is to investigate the heterogeneity (both intratumoral and intertumoral) of HER2 expression in GC, and the relationship between heterogeneity and the clinicopathological features.

METHODS

A total of 618 patients with primary gastric adenocarcinoma were recruited, and two formalin-fixed paraffin-embedded (FFPE) tumor-containing blocks of each patient were selected for HER2 immunohistochemical (IHC) assay. Clinicopathological characteristics were recorded, and intratumoral and intertumoral heterogeneity of HER2 IHC expression was determined.

RESULTS

The results indicated that the dual-block assays significantly increased the HER2 overexpression (IHC 2+ and 3+) rate compared with the single paraffin block detection. Approximately 50 % of the cases showed intratumoral HER2 heterogeneity within a single tissue section, and 30.10 % of cases showed intertumoral heterogeneity between a patient's two blocks. Furthermore, intertumoral heterogeneity was associated with tumors of small size (P = 0.029) and distal location (P = 0.032) characters, while the intratumoral heterogeneity was correlated with poorly differentiated carcinomas. Laurén's diffuse type showed a notably higher intratumoral heterogeneity rate, and the mixed type exhibited higher intertumoral HER2 discordance between the dual-block cohorts (P < 0.001). Besides, HER2 heterogenous overexpression was not associated with age, gender, type of resection, lymphatic or venous invasion, perineural invasion or pTNM (P > 0.05) for both cohorts.

CONCLUSION

The research findings in this paper indicate that the intratumoral and intertumoral heterogeneity of HER2 overexpression is common in GC patients, and these variations are associated with certain clinicopathological features. We highly recommend multi-block HER2 assessment for accurate diagnosis of GC.

Impact of 68Ga-NOTA-MAL-MZHER2 PET imaging in advanced gastric cancer patients and therapeutic response monitoring

PURPOSE

Clinical PET imaging of human epidermal growth factor receptor 2 (HER2) can noninvasively detect HER2 overexpression in lesions. A novel ⁶⁸Ga-NOTA-MAL-MZHER2 (⁶⁸Ga-HER2) affibody was developed for clinical PET/CT, and its safety, tissue dosimetry, ability to detect HER2-positive lesions, and utility for HER2-targeted therapy in patients with advanced gastric cancer (AGC) were evaluated.

METHODS

Thirty-four patients with AGC (23 with HER2-positive and 11 with HER2-negative primary lesions) were included and underwent PET/CT after an injection of approximately 3.7 MBq/kg body weight ⁶⁸Ga-HER2 affibody. Thirteen patients (8 HER2-positive and 5 HER2-negative patients) were scanned at 1, 2, and 3 h post-injection to determine the best imaging timepoint, and the remaining patients were scanned at the optimized timepoint. All patients underwent standard ¹⁸F-FDG PET/CT within 7 d to identify viable lesions. The SUV_max of lesions larger than 1.0 cm were analyzed. Five lesion maxima were analyzed for each organ.

RESULTS

(1) The ⁶⁸Ga-HER2 affibody was safe and effective, and optimal image contrast was observed 2 h post-injection; the average effective absorbed dose was 0.0215 mSv/MBq. (2) The HER2-positive group had significantly higher ⁶⁸Ga-HER2 affibody uptake than the HER2-negative group (SUV_max 10.7 ± 12.5 vs 3.8 ± 1.7, p = 0.005). The specificity and sensitivity were 100 and 55.4%, respectively, with a SUV_max cutoff value of 6.6. The SUV_max of the lesions ranged from 1.6 to 73.0, suggesting heterogeneity in HER2 expression. (3) ⁶⁸Ga-HER2 affibody uptake showed an organ-dependent difference in patients with HER2-positive expression. Bone metastases had the highest uptake (SUV_max 40.5 ± 24.9), followed by liver metastases (SUV_max 11.9 ± 3.9) and lymph node metastases (SUV_max 5.6 ± 3.7), while the uptake in other lesions, including in the primary lesion, was relatively lower (SUV_max 7.3 ± 3.7). (4) Patients receiving therapy had a non-significantly lower lesion SUV_max than patients not receiving therapy (SUV_max 8.8 ± 4.9 vs 11.8 ± 15.2) (p = 0.253). Additionally, the ⁶⁸Ga-HER2 affibody detected positive lesions in 1/11 patients with HER2-negative primary gastric cancer, which was confirmed by second generation gene sequencing. (5) Moreover, ten patients underwent baseline PET/CT followed by targeted anti-HER2 therapy. Patients with lesions showing high avidity to the ⁶⁸Ga-HER2 affibody showed longer progression-free survival (PFS) than those with lesions showing low avidity (4-9 m vs 2-3 m).

CONCLUSION

⁶⁸Ga-HER2 affibody PET/CT is a feasible method to noninvasively detect the HER2 status in AGC patients and enable early detection with a low dose. Ongoing anti-HER2 therapy did not influence ⁶⁸Ga-HER2 affibody imaging, which allowed repeated evaluations to monitor the HER2 status after anti-HER2 therapy. This method provides an in vivo understanding of AGC biology that will ultimately help oncologists improve individualized therapy plans.

The age variation of HER2 immunohistochemistry positive rate in biopsy specimens of gastric cancer

AIMS

The aim of this study was to explore HER2 status and characteristics in biopsy specimens of gastric cancer (GC) in Chinese population.

METHODS AND RESULTS

A total of 27,787 biopsy specimens of GC from 103 hospitals were obtained. Immunohistochemistry (IHC) staining of HER2 was performed. Overall HER2 IHC positive rate was 11.2 %. HER2 positive rate elevated with the increase of age in total patients and both genders. The rates were 7.1 %, 8.1 %, 9.0 %, 10.9 %, 11.8 %, 12.6 %, and 12.1 % when patient age was ≤30, 31-40, 41-50, 51-60, 61-70, 71-80, and >80, respectively (P < 0.001). In male, the rates were 6.5 %, 8.4 %, 9.6 %, 11.5 %, 12.4 %, 13.3 %, and 12.1 % (P < 0.001). In female, the rates were 7.4 %, 7.9 %, 8.0 %, 9.0 %, 9.6 %, 10.6 %, and 11.9 % (P = 0.128). The changes in male were more dramatic than in female (P < 0.001). Furthermore, the proportion of the intestinal type GCs increased with age in total patients and both genders (P < 0.001), and in male the changes were more dramatic (P < 0.001). While the proportion of the diffuse type showed the opposite tendency to that of the intestinal type (P < 0.001). HER2 IHC positive rate showed a positive correlation with the proportion of the intestinal type (r=0.986, P < 0.001), and a negative correlation with the proportion of the diffuse type (r=0.984, P < 0.001).

CONCLUSIONS

The HER2 IHC positive rate showed age variation in biopsy specimens of GC. In male the variation was more dramatic than in female. The variation of HER2 positive rate can be attributed to the age variation of the Lauren subtypes.

Late stage gastric cancer patients with extra gained HER2 positivity by dual block assessment may not show compromised efficacy to trastuzumab treatment

Dual block HER2 assessment can effectively increase the HER2 positive rate in resected specimens of gastric cancer (GC). The aim of this study is to explore whether GC patients with extra gained HER2 positivity by dual block assessment can benefit from trastuzumab therapy. Twenty-eight GC patients receiving gastrectomy prior to trastuzumab treatment were retrospectively analyzed. All the cases routinely accepted dual block HER2 assessment. The cases were divided into 2 cohorts based on HER2 status: cohort A with concordant HER2 results and cohort B with discordant HER2 results between the two blocks (cases with extra gained HER2 positivity). Response rate (RR), progress free survival (PFS) and overall survival (OS) were compared between the two cohorts. The results showed that no significant differences were found between the two cohorts in main clinicopathologic characteristics. No statistical difference was found in response rate (47.6% vs 57.1%) (P=1.0), either. The two cohorts did not demonstrate statistical differences in the PFS (10.5 months (95%CI 6.4-14.6) vs 8.0 months (95%CI 3.2-12.8), P=0.686) and the OS (23.3 months (95%CI 12.1-34.5) vs 20.0 months (95%CI 10.1-29.9), P=0.776). In conclusion, our study suggests that patients with extra gained HER2 positivity may not show compromised efficacy to trastuzumab treatment.

HER2-targeted therapies - a role beyond breast cancer

HER2 is an established therapeutic target in a large subset of women with breast cancer; a variety of agents including trastuzumab, pertuzumab, lapatinib, neratinib and trastuzumab emtansine (T-DM1) have been approved for the treatment of HER2-positive breast cancer. HER2 is also overexpressed in subsets of patients with other solid tumours. Notably, the addition of trastuzumab to first-line chemotherapy has improved the overall survival of patients with HER2-positive gastric cancer, and has become the standard-of-care treatment for this group of patients. However, trials involving pertuzumab, lapatinib and T-DM1 have failed to provide significant improvements in the outcomes of patients with HER2-positive gastric cancer. HER2-targeted therapies are also being tested in patients with other solid tumours harbouring HER2 overexpression, and/or amplifications or other mutations of the gene encoding HER2 (ERBB2), including biliary tract, colorectal, non-small-cell lung and bladder cancers. The experience with gastric cancer suggests that the successes observed in HER2-positive breast cancer might not be replicated in these other tumour types, owing to differences in the level of HER2 overexpression and other aspects of disease biology. In this Review, we describe the current role of HER2-targeted therapies beyond breast cancer and also highlight the potential of novel HER2-targeted agents that are currently in clinical development.

A survival guide to HER2 testing in gastric/gastroesophageal junction carcinoma

Human epidermal growth factor receptor 2 (HER2) status determines gastric/gastroesophageal junction (GEJ) adenocarcinomas that benefit from targeted therapy; hence, HER2 testing has become a routine practice. Accurate HER2 testing is fundamental to select eligible patients who will benefit from HER2-targeted treatment. The reported HER2-positive rate in gastric/GEJ cancers ranges from 4.4% to 53.4%, and HER2-positive tumors are considered to have more-aggressive biologic behavior and tumor recurrence. Main modalities of HER2 testing in clinical practice include immunohistochemistry (IHC) for protein expression and in situ hybridization (ISH) for gene amplification. Many technical pitfalls affect the accuracy of HER2 result. Additionally, several issues in HER2 testing are related to the tumor biology, sample selection, interpretation of IHC and ISH results, and confirming HER2 status. Therefore, gastric/GEJ adenocarcinoma-specific HER2 testing protocols have been developed and standardized to minimize the impact of these preanalytical and analytical factors and to enhance reproducibility of HER2 testing results. This review provides up-to-date practical guidance to clinicians on accurate HER2 testing and interpretation of results in gastric/GEJ adenocarcinoma.

The Chinese Society of Clinical Oncology (CSCO): clinical guidelines for the diagnosis and treatment of gastric cancer

China is one of the countries with the highest incidence of gastric cancer. There are differences in epidemiological characteristics, clinicopathological features, tumor biological characteristics, treatment patterns, and drug selection between gastric cancer patients from the Eastern and Western countries. Non-Chinese guidelines cannot specifically reflect the diagnosis and treatment characteristics for the Chinese gastric cancer patients. The Chinese Society of Clinical Oncology (CSCO) arranged for a panel of senior experts specializing in all sub-specialties of gastric cancer to compile, discuss, and revise the guidelines on the diagnosis and treatment of gastric cancer based on the findings of evidence-based medicine in China and abroad. By referring to the opinions of industry experts, taking into account of regional differences, giving full consideration to the accessibility of diagnosis and treatment resources, these experts have conducted experts' consensus judgement on relevant evidence and made various grades of recommendations for the clinical diagnosis and treatment of gastric cancer to reflect the value of cancer treatment and meeting health economic indexes. This guideline uses tables and is complemented by explanatory and descriptive notes covering the diagnosis, comprehensive treatment, and follow-up visits for gastric cancer.

HER2 as a limited predictor of the therapeutic response to neoadjuvant therapy in locally advanced rectal cancer

Human epidermal growth factor 2 (HER2) is a candidate therapeutic and prognostic marker for rectal cancer treated with neoadjuvant chemoradiotherapy. The specific frequency and prognostic role of HER2 protein expression and HER2 gene amplification in those rectal cancers has not been fully investigated. Pretreatment biopsied and surgically resected formalin-fixed paraffin-embedded tissues from 74 patients were retrospectively evaluated for HER2 protein expression and HER2 gene copy number using immunohistochemistry (IHC) and silver in situ hybridization (SISH), respectively. The tumor response to chemoradiation was evaluated with TNM staging and tumor regression grading (TRG) systems. Good response to chemoradiation therapy (TRG3), poor response (22 TRG1 and 19 TRG2), and TNM downstaging achieved in 33 (44.6%), 41 (55.4%), and 42 (56.8%) patients, respectively. The frequency of HER2 positivity is 17.6%, all of which were low-level HER2 gene amplification with 2.2 of median gene copy number ratio, detected in IHC0 (3/39), IHC1+ (2/18), IHC2+ (5/14) and IHC3+ (2/3). There was no association of HER2 positivity with clinicopathological parameters or survival. However, older age (≥61 years) and HER2 positivity were the independent predictive factors for non-down staging, while poorly differentiation and the papillary pattern were predictors for poor response. In multivariate analysis, good response proved as an only independent favorable prognostic factor affecting survivals. In conclusion, HER2 positivity may be predictive for a high-risk therapeutic resistance in rectal cancers. The discrepancy between IHC and gene amplification may result from the low-level amplification, which may explain lack of prognostic impact of HER2 positivity.

Associations between CA19-9 and CA125 levels and human epidermal growth factor receptor 2 overexpression in patients with gastric cancer

The aim of the present study was to investigate the association between serum carbohydrate antigen (CA)19-9 and CA125 levels, and human epidermal growth factor receptor 2 (HER2) expression in patients with gastric cancer, as well as to identify any correlation between them and the risk of recurrence and metastasis. A total of 256 patients were enrolled in the present study, and 219 patients were followed-up to investigate recurrence and metastasis of gastric cancer. Immunohistochemistry was used to detect HER-2 in gastric adenocarcinoma and paracancerous tissues. The positive rate of CA19-9 and CA125 in stages III/IV was higher compared with that in stages I/II. The positive rate of HER2 in distinct stages of gastric cancer was not statistically different. Serum CA19-9 and CA125 were not associated with the positive expression of HER2. The recurrence and metastasis of CA19-9, CA125 and HER2-positive gastric cancer were increased compared with those experienced by CA19-9, CA125 and HER2-negative patients. Age, stage and preoperative tumor markers were associated with 3-year prognosis of gastric cancer. HER2 [odds ratio (OR)=2.55] and CA19-9 (OR=1.22) were independent prognostic factors in patients with gastric cancer. CA19-9, CA125 and HER2 may be used to predict the recurrence or metastasis of gastric cancer. The combined detection may be able to improve the sensitivity and efficiency of predicting the recurrence or metastasis of gastric cancer. Preoperative positive serum for CA19-9 and CA125 were associated with poor prognosis in patients with gastric cancer. CA19-9 and HER2 were independent prognostic factors of gastric cancer.

Poor efficacy response to trastuzumab therapy in advanced gastric cancer with homogeneous HER2 positive and non-intestinal type

Introduction

Factors affecting trastuzumab efficacy in advanced gastric cancer (GC) are largely unknown. Heterogeneity is a notable feature of HER2 in GC. Whether the heterogeneity influences trastuzumab efficacy is still unknown.

Results

The HER2^homogeneous group and HER2^{heterogeneous} group showed no statistical difference in RR (46.4% vs 55.0%, P = 0.558), PFS (5.80 vs 6.30 months, P = 0.804) and OS (16.00 vs 16.00 months, P = 0.787). The Lauren^intestinal group and Lauren^{non-intestinal} group demonstrated no discrepancy in PFS (6.00 vs 6.00 months, P = 0.912) and OS (16.50 vs 14.00 months, P = 0.227). However, by combining HER2 heterogeneity and Lauren classification, PFS and OS of HER2^homogeneous/Lauren^{non-intestinal} subgroup was the shortest among the 4 subgroups (P = 0.012 and P = 0.037), which was much shorter than the other patients (PFS:3.00 vs 6.30 months, P = 0.003; OS: 4.50 vs 16.50 months, P = 0.004). Univariate and multivariate analysis showed that HER2 heterogeneity combined with Lauren classification was an independent prognostic factor in both PFS (P = 0.031 and P = 0.002) and OS (P = 0.039 and P = 0.013).

Materials and Methods

48 patients with HER2 positive advanced GCs accepting trastuzumab treatment were retrospectively analyzed. Based on HER2 heterogeneity, the patients were divided into a HER2^homogeneous group and a HER2^{heterogeneous} group. Response rate (RR), progression free survival (PFS), and overall survival (OS) were compared. Main clinicopathological factors including Lauren classification were subjected to subgroup analysis.

Conclusions

HER2 heterogeneity alone may not correlate with trastuzumab efficacy in HER2 positive advanced GCs. HER2 heterogeneity combined with Lauren classification may help to identify a subgroup with poor response to trastuzumab which is homogeneous HER2 positive and non-intestinal type.

Improving accuracy of breast cancer biomarker testing in India

There is a global mandate even in countries with low resources to improve the accuracy of testing biomarkers in breast cancer viz. oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2neu) given their critical impact in the management of patients. The steps taken include compulsory participation in an external quality assurance (EQA) programme, centralized testing, and regular performance audits for laboratories. This review addresses the status of ER/PR and HER2neu testing in India and possible reasons for the delay in development of guidelines and mandate for testing in the country. The chief cause of erroneous ER and PR testing in India continues to be easily correctable issues such as fixation and antigen retrieval, while for HER2neu testing, it is the use of low-cost non-validated antibodies and interpretative errors. These deficiencies can however, be rectified by (i) distributing the accountability and responsibility to surgeons and oncologist, (ii) certification of centres for testing in oncology, and (iii) initiation of a national EQA system (EQAS) programme that will help with economical solutions and identifying the centres of excellence and instill a system for reprimand of poorly performing laboratories.

HER2 testing in advanced gastric and gastro-oesophageal cancer: analysis of an Australia-wide testing program

This Australian human epidermal growth factor receptor 2 (HER2) testing program aimed to analyse >800 cases tested in a coordinated setting to further evaluate the criteria to establish HER2 status in advanced gastric and gastro-oesophageal junction (GOJ) cancer. Heterogeneity, and minimum number of biopsy fragments for reliable HER2 assessment were also examined in a subset of samples. Five laboratories tested 891 samples referred to determine HER2 status for potential anti-HER2 treatment. Cancer site, specimen type (endoscopic biopsy/resection/metastases), immunohistochemistry (IHC) score, HER2 gene and CEP17 copy number (CN) and HER2:CEP17 ratios were recorded. Samples were derived from stomach (53.1%), GOJ (28.2%) or metastases (18.5%). IHC for HER2 and dual probe HER2:CEP17 in situ hybridisation (ISH) were performed in parallel. A stringent definition (SD) of HER2 positivity was used (IHC2+/3+ plus CN>6 and ratio>2) and compared with other published criteria. HER2 positive rate was 13.9% (114/820) by SD, and 12.9-16.0% using other definitions. There was higher concordance between IHC and HER2 CN by ISH than with ratio. The HER2 positive rate was significantly higher in GOJ samples than others (p = 0.03) and in endoscopic biopsies than resections (p = 0.047). In a subset of 98 positive cases, 39 (39.8%) showed heterogeneity, and in 282 endoscopic biopsies positivity rate plateaued at five tumour fragments, suggesting this is the minimum number of biopsies that should be examined.

Development of mesenchymal subtype gene signature for clinical application in gastric cancer

Previously, in the Asian Cancer Research Group (ACRG) project, we defined four distinct molecular subtypes in gastric cancer (GC). Mesenchymal (microsatellite stable with epithelial-to-mesenchymal transition phenotype, MSS/EMT) tumors showed the worst prognosis among all the subtypes. To develop a gene signature for predicting mesenchymal subtype GC, we conducted gene expression profiling using a NanoString assay in 70 ACRG specimens. The gene signature was validated in an independent set obtained from the prospective Adjuvant chemoRadioTherapy In Stomach Tumor (ARTIST) trial. The association between the mesenchymal subtype and survival was investigated. After cross-platform concordance test performed in 70 ACRG specimens, a 71-gene MSS/EMT signature was obtained. In the validation set, the gene signature predicted that 20 of 73 (27%) patients had mesenchymal tumors. Patients with mesenchymal subtype had diffuse GC, poorly-differentiated or signet ring cell carcinoma, and were microsatellite stable. The estimated hazard ratio for survival in patients with mesenchymal GC compared to those with non-mesenchymal tumors was 2.262 (95% confidence interval, 1.410 to 3.636; P=0.001). The survival difference remained significant when the subtypes were analyzed according to clinical prognostic parameters. This study suggested that the NanoString-based 71-gene signature for mesenchymal subtype is a strong predictor of the outcome in patients with GC.

A nCounter CNV Assay to Detect HER2 Amplification: A Correlation Study with Immunohistochemistry and In Situ Hybridization in Advanced Gastric Cancer

AIM

Screening amplified genes for targeted therapy with high-throughput technology is very important. The NanoString nCounter system allows multiplexed digital quantification of target molecules through the use of color-coded barcodes with the great advantage that formalin-fixed, paraffin-embedded (FFPE) tissue can be utilized.

METHODS

We tested nCounter custom copy number variation (CNV) panels in 220 gastric cancer samples and evaluated the utility of this method as a screening tool for the detection of CNV using HER2. For the validation of results, we compared the nCounter results with immunohistochemistry (IHC), and we further performed in situ hybridization (ISH) in discrepant cases.

RESULTS

The average HER2 gene copy numbers (CNs) by nCounter were 17.25, 2.0 and 2.61 for the HER2 IHC positive (3+), equivocal (2+), and negative cases, respectively. Out of the 16 IHC 3+ cases, 13 (81.3 %) were reported as HER2 CN gain (≥4). Gastric cancers with homogeneous HER2 overexpression or high tumor purity showed HER2 CN ≥10. Among the 192 cases with HER2 IHC negative and without HER2 gene amplification, 29 showed a HER2 CN ≥4 with the nCounter assay. The nCounter assay had a concordance rate of 83.4 % (kappa value, 0.35), a sensitivity of 66.7 %, a specificity of 85.2 %, a negative predictive value of 96 %, and a positive predictive value of 32.6 % compared with HER2 IHC/ISH results. Fresh frozen (FF) samples revealed a higher concordance rate (91.5 %, kappa value, 0.59) than FFPE samples (78.5 %, kappa value 0.27) and showed a high specificity (97.2 %).

CONCLUSION

The nCounter CNV assay is a reliable and practical method to detect high CN variations. Given the intra-tumoral HER2 heterogeneity and normal cell contamination, additional IHC and/or FISH is necessary and needs caution in interpretation, especially in FFPE tissue samples.

Tumor containing fragment number influences immunohistochemistry positive rate of HER2 in biopsy specimens of gastric cancer

Background

HER2 assessment in biopsy specimens of gastric cancer (GC) is challenging because of the intratumoral heterogeneity. False negative results may be get because of limited biopsy material. The aim of this study is to explore how tumor-containing fragment number and biopsy specimen number affect HER2 immunohistochemistry (IHC) positive rate.

Methods

Eight hundred and ninety biopsy specimens and 459 paired resected specimens were collected. IHC staining of HER2 was performed. HER2 IHC positive (scored 3+) rate was compared based on tumor-containing fragment number, biopsy specimen number, average size and tumor tissue proportion of tumor-containing fragments. The positive predictability of biopsy specimens to resected specimens was analyzed based on tumor fragment number.

Results

HER2 IHC positive rates were 2.0, 3.5, 7.0, 13.2, 17.1, and 15.9% when tumor fragment numbers were 1, 2, 3, 4, 5 and 6 respectively. The rate rose with the increase of tumor fragment number (P = 0.004). ROC curve analysis showed that biopsy specimens exhibited positive predictability when tumor fragment number reached 3, but showed better performance when the number was ≥4 (P < 0.05). After fragment number reached 4, no statistic differences were reached in either HER2 IHC positive rate or positive predictability with further increase of the number (P > 0.05). HER2 IHC positive rate was not associated with biopsy number (P = 0.127), average size of tumor fragments (P = 0.397), and tumor tissue proportion of tumor fragments (P = 0.825) directly.

Conclusions

The number of tumor-containing fragments influences HER2 IHC positive (scored 3+) rate. Greater than or equal to 4 (≥4) tumor fragments give better results in the positive rate as well as positive predictability. We recommend the number of tumor containing fragments be described in the HER2 IHC pathology reports for clinical reference in endoscopic biopsy specimens of GC.

Molecular Testing for Gastrointestinal Cancer

With recent advances in molecular diagnostic methods and targeted cancer therapies, several molecular tests have been recommended for gastric cancer (GC) and colorectal cancer (CRC). Microsatellite instability analysis of gastrointestinal cancers is performed to screen for Lynch syndrome, predict favorable prognosis, and screen patients for immunotherapy. The epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor has been approved in metastatic CRCs with wildtype RAS (KRAS and NRAS exon 2-4). A BRAF mutation is required for predicting poor prognosis. Additionally, amplification of human epidermal growth factor receptor 2 (HER2) and MET is also associated with resistance to EGFR inhibitor in metastatic CRC patients. The BRAF V600E mutation is found in sporadic microsatellite unstable CRCs, and thus is helpful for ruling out Lynch syndrome. In addition, the KRAS mutation is a prognostic biomarker and the PIK3CA mutation is a molecular biomarker predicting response to phosphoinositide 3-kinase/AKT/mammalian target of rapamycin inhibitors and response to aspirin therapy in CRC patients. Additionally, HER2 testing should be performed in all recurrent or metastatic GCs. If the results of HER2 immunohistochemistry are equivocal, HER2 silver or fluorescence in situ hybridization testing are essential for confirmative determination of HER2 status. Epstein-Barr virus-positive GCs have distinct characteristics, including heavy lymphoid stroma, hypermethylation phenotype, and high expression of immune modulators. Recent advances in next-generation sequencing technologies enable us to examine various genetic alterations using a single test. Pathologists play a crucial role in ensuring reliable molecular testing and they should also take an integral role between molecular laboratories and clinicians.

HER2 Amplification and Cetuximab Efficacy in Patients With Metastatic Colorectal Cancer Harboring Wild-type RAS and BRAF

BACKGROUND

Cetuximab has shown clinical benefit in patients with metastatic colorectal cancer (mCRC) harboring wild-type RAS. Human epidermal growth factor receptor 2 (HER2) amplification may be a mechanism of cetuximab resistance. We evaluated the association between HER2 amplification and cetuximab efficacy in patients with mCRC harboring wild-type RAS and BRAF.

PATIENTS AND METHODS

Between December 2003 and June 2013, we identified 142 patients with mCRC whose tumors harbored both wild-type exons 2, 3, and 4 in KRAS and NRAS, and wild-type exon 15 in BRAF using high throughput sequencing (OncoMap version 4.0). All patients received cetuximab after oxaliplatin, irinotecan, and fluoropyrimidine failure. HER2 status was determined using immunohistochemistry and silver in situ hybridization (SISH) and correlated with cetuximab efficacy.

RESULTS

Of 142 RAS and BRAF wild-type tumors, we observed 7 cases (4.9%) of HER2 amplification by SISH. After a median follow-up of 13.2 months (range, 1.4-78.1 months), median progression-free survival (PFS) was significantly different according to HER2 status: 3.1 months in patients with HER2 amplification compared with 5.6 months in those with non-amplified HER2 (hazard ratio, 2.73; 95% confidence interval, 1.18-6.31; P = .019). Overall survival (OS) was not significantly different between groups, although there was a tendency towards shorter OS in patients with HER2-amplified tumors (hazard ratio, 1.31; 95% confidence interval, 0.61-2.82; 10.1 vs. 13.5 months; P = .488).

CONCLUSIONS

HER2 amplification is predictive of shorter PFS after cetuximab treatment in patients with mCRC harboring wild-type RAS and BRAF. Further study is warranted for this patient population.

Ideal number of biopsy tumor fragments for predicting HER2 status in gastric carcinoma resection specimens

Intratumoral heterogeneity of HER2 expression is common in gastric cancers and pose a challenge for identifying patients who would benefit from anti-HER2 therapy. The aim of this study is to compare HER2 expression in biopsy and resection specimens of gastric carcinoma by immunohistochemistry (IHC) and to find the ideal number of biopsy tumor fragments that can accurately predict HER2 overexpression in the corresponding surgically resected specimen. The HER2 IHC results of 702 paired biopsy and resection specimens of gastric cancer were compared.The mean number of biopsy fragments among all cases was 4.3 (range 1-11). HER2 was positive in 130 (18.5%) endoscopic biopsies and in 102 (14.5%) gastrectomy specimens. Intratumoral heterogeneity of HER2 was found in 80 (61.5%) biopsies and 70 (68.6%) resection specimens. Out of the 70 surgical specimens with intratumoral heterogeneity, 24 (34.3%) of the corresponding biopsies were categorized as negative (positive conversion). In the 86 (12.3%) discrepant cases, negative conversion was observed in 57 (66.3%) cases and positive conversion in 29 (33.7%). The fragment numbers were significantly correlated with the discrepancy of results and positive predictability (P = 0.0315 and P = 0.0052). ROC curve analysis and positive predictability showed that 4 fragments should be obtained to minimize the differences in HER2 scores between biopsy and resection specimen.In gastric carcinomas with discrepant HER2 results between biopsy and surgical resection specimens, intratumoral heterogeneity is common with most of them showing positive conversion. To predict HER2 status precisely, at least 4 biopsy fragments containing tumor cells are required.

Concordance of HER2 expression in paired primary and metastatic sites of gastric and gastro-oesophageal junction cancers

HER2 is amplified/overexpressed in a subset of gastric and gastro-oesophageal junction cancers. Addition of anti-HER2 therapy has been shown to provide survival benefit in this setting. However, there are limited data assessing the concordance of HER2 status between primary and metastatic sites.A total of 113 samples from 43 paired primary and metastatic tumours were tested for HER2 status, by immunohistochemistry (IHC) for protein expression and silver in situ hybridisation (SISH) for gene amplification.Primary sites tested included endoscopic biopsies (n = 30) and resections (n = 24). Metastatic samples included lymph nodes (n = 29), peritoneal effusions (n = 21) and miscellaneous sites (n = 9). The overall HER2+ rate was 11%. Of 41 (95%; 95% CI 88.5-100%) concordant cases, 38 were HER2- and three were HER2+. There were two (5%) discordant cases, one of which showed heterogeneity of HER2 expression.This series confirms a high concordance rate of 95%, supporting that testing of primary tumours and metastases is equally valid and providing clinical rationale for the addition of anti-HER2 therapy in HER2+ disseminated disease.

Companion diagnostics for the targeted therapy of gastric cancer

Gastric cancer is the fourth most common type of cancer and represents a major cause of cancer-related deaths worldwide. With recent biomedical advances in our understanding of the molecular characteristics of gastric cancer, many genetic alterations have been identified as potential targets for its treatment. Multiple novel agents are currently under development as the demand for active agents that improve the survival of gastric cancer patients constantly increases. Based on lessons from previous trials of targeted agents, it is now widely accepted that the establishment of an optimal diagnostic test to select molecularly defined patients is of equal importance to the development of active agents against targetable genetic alterations. Herein, we highlight the current status and future perspectives of companion diagnostics in the treatment of gastric cancer.

A Retrospective Analysis for Patients with HER2-Positive Gastric Cancer Who Were Treated with Trastuzumab-Based Chemotherapy: In the Perspectives of Ethnicity and Histology

PURPOSE

While the Trastuzumab for Gastric Cancer (ToGA) trial demonstrated the efficacy and safety of trastuzumab-based chemotherapy in HER2-positive metastatic gastric cancer, the overall survival (OS) benefit was not found in Asian and diffuse-type cancer patients. The aim of the study is to investigate predictive markers for trastuzumab-based chemotherapy.

MATERIALS AND METHODS

Data of patients with HER2-positive gastric cancer treated with trastuzumab-based chemotherapy were analyzed retrospectively.

RESULTS

A total of 168 Asian patients were included. The median age was 60 years (range, 27 to 85 years) and the male:female ratio was 118 (70.2%):50 (29.8%). Fourteen (8.3%), 63 (37.5%), 75 (44.6%), and 11 (6.5%) patients had well, moderately, poorly-differentiated tubular adenocarcinoma and signet ring cell carcinoma, respectively. With 14 complete responses and 73 partial responses, the response rate was 50.6%. The median progression-free survival (PFS) was 10.2 months (95% confidence interval [CI], 8.7 to 11.7), and the median OS was 18.5 months (95% CI, 16.4 to 50.6). Next, we investigated the effect of poorly-differentiated histology (PDH, poorly-differentiated tubular adenocarcinoma+signet ring cell carcinoma) on clinical outcomes. The median PFS (8.9 months vs. 11.5 months, p=0.16) was slightly inferior in PDH patients, and the median OS was significantly shorter in PDH patients (14.6 months vs. 19.0 months, p=0.025).

CONCLUSION

While subset analysis of the ToGA trial demonstrated that trastuzumab-based chemotherapy may not be beneficial for Asians and patients with PDH, our data may suggest that even in Asian patients and patients with PDH, trastuzumab-based chemotherapy could be associated with improved clinical outcomes in patients with HER2-positive gastric cancer.