Next-Generation Sequencing Panel for 1p/19q Codeletion and IDH1-IDH2 Mutational Analysis Uncovers Mistaken Overdiagnoses of 1p/19q Codeletion by FISH

The 1p/19q codeletion is the result of a translocation between chromosome 1 (Chr1p) and chromosome 19 (Chr19q) with the loss of derivative (1;19)(p10;q10) chromosome. The 1p/19q codeletion has predictive and prognostic significance, and it is essential for the classification of gliomas. In routine practice, the fluorescence in situ hybridization (FISH) diagnosis of 1p/19q codeletion is sometimes unexpected. This study aimed to develop a next-generation sequencing panel for the concurrent definition of the 1p/19q codeletion and IDH1/IDH2 mutation status to resolve these equivocal cases. A total of 65 glioma samples were investigated using a 1p/19q-single-nucleotide polymorphism (SNP)-IDH panel. The panel consists of 192 amplicons, including SNPs mapping to Chr1 and Chr19 and amplicons for IDH1/IDH2 analysis. The 1p/19q SNP-IDH panel consistently identified IDH1/IDH2 mutations. In 49 of 60 cases (81.7%), it provided the same 1p/19q results obtained by FISH. In the remaining 11 cases, the 1p/19q SNP-IDH panel uncovered partial chromosome imbalances as a result of interstitial amplification or deletion of the regions where the FISH probes map, leading to a mistaken overdiagnosis of 1p/19q codeletion by FISH. The 1p/19q SNP-IDH next-generation sequencing panel allows reliable analysis of the 1p/19q codeletion and IDH1/IDH2 mutation at the same time. The panel not only allows resolution of difficult cases but also represents a cost-effective alternative to standard molecular diagnostics procedures.

Chromosome X aneusomy and androgen receptor gene copy number aberrations in apocrine carcinoma of the breast

Carcinomas with apocrine differentiation (CAD) of the breast are rare tumours typically presenting high immunohistochemical expression of androgen receptor (AR) which is a target molecule for personalised therapy. To date, no studies have evaluated the genetic changes that are associated with AR immunohistochemical expression in CADs. The present work aims to characterise AR status in CADs. Twenty CAD tumours were studied with immunohistochemistry, in situ fluorescence hybridization and DNA methylation analysis, to evaluate AR expression and its regulator status. All tumours demonstrated high AR immunohistochemical expression, with over 95% of the neoplastic cells showing AR positivity in 19/20 cases. CADs showed AR gene copy loss in a percentage of neoplastic cells ranging from 5 to 84% (mean 48.93%). AR regulator genes, including the MAGE family, UXT and FLNA, presented variable methylation levels, but were mainly hypomethylated and therefore all transcriptionally active. The results of this study indicate that CADs present AR monosomy, paralleled by higher transcriptional activity of the gene with potential to influence response to AR deprivation therapy.

HER2 Overexpression and Amplification in Feline Pulmonary Carcinoma

HER2 is overexpressed, amplified, and mutated in a subset of human lung cancer. The aim of this study was to investigate HER2 protein overexpression and gene amplification in feline pulmonary carcinomas. Thirteen pulmonary carcinomas were selected and TTF-1 and HER2 expression was evaluated by immunohistochemistry. Fluorescence in situ hybridization (FISH) was performed with a HER2 probe and a BAC probe for the feline chromosome E1p1.12-p1.11 region. Twelve adenocarcinomas and 1 squamous cell carcinoma were diagnosed. TTF-1 was positive in 7 carcinomas (58%). HER2 was overexpressed in 2 (15%), equivocal in 5 (38%), and negative in 6 cases (46%). FISH analysis of HER2 was indeterminate in 2 cases. Three pulmonary carcinomas (27%) had HER2 amplification and 8 cases were not amplified (73%). The significant correlation between HER2 protein overexpression and gene amplification are promising preliminary data, but study of additional cases is needed to confirm HER2 as a target for possible innovative treatments.

Postsurgical Approaches in Low-Grade Oligodendroglioma: Is Chemotherapy Alone Still an Option?

BACKGROUND

Patients with low-grade gliomas (LGGs) with isocitrate dehydrogenase (IDH) mutation (mut) and 1p19q codeletion (codel) have a median overall survival of longer than 10 years. The aim of this study is to assess the role of postsurgical treatments.

SUBJECTS, MATERIALS, AND METHODS

We evaluated patients with LGGs with IDH mut and 1p19q codel; IDH1/2 was performed by immunohistochemistry and quantitative polymerase chain reaction. In all wild-type cases, we performed next-generation sequencing. 1p19 codel analysis was performed by fluorescence in situ hybridization.

RESULTS

Among the 679 patients, 93 with LGGs with IDH mutation and 1p19q codel were included. Median follow-up (FU) was 96.1 months. Eighty-four patients (90.3%) were high risk according to Radiation Therapy Oncology Group criteria. After surgery, 50 patients (53.7%) received only FU, 17 (18.3%) chemotherapy (CT), and 26 (30.1%) radiotherapy (RT) with (RT + CT, 8 patients, 8.6%) or without (RT, 18 patients, 19.4%) chemotherapy. Median progression-free survival (mPFS) was 46.3 months, 50.8 months, 103.6 months, and 120.2 months in patients with FU alone, with CT alone, with RT alone, or with RT + CT, respectively. Median PFS was significantly longer in patients who received postsurgical treatment (79.5 months, 95% confidence interval [CI]: 66.4-92.7) than patients who received FU (46.3 months, 95% CI: 36.0-56.5). Moreover, mPFS was longer in patients who received RT (alone or in combination with CT, n = 26, 113.8 months, 95% CI: 57.2-170.5) than those who did not (n = 67, 47.3 months, 95% CI: 36.4-58.2). In particular, temozolomide alone did not improve PFS with respect to FU.

CONCLUSION

RT with or without chemotherapy, but not temozolomide alone, could extend PFS in IDH mut 1p19q codel LGGs.

IMPLICATIONS FOR PRACTICE

Low-grade gliomas with high-risk features, defined according to Radiation Therapy Oncology Group criteria, receive radiotherapy and/or chemotherapy as postsurgical treatments. Radiotherapy, however, has serious long-term effects (cognitive impairment), which are to be taken into account in these young patients. Moreover, low-grade gliomas with isocitrate dehydrogenase mutation and 1p19q codeletion (oligodendrogliomas) have an extremely long survival and a better prognosis. This study suggests that postsurgical treatments prolong the time before tumor progression in patients with good prognosis as well as those with oligodendroglioma. Moreover, temozolomide alone might not be effective in prolonging progression-free survival.

HER2 Amplification Status in Feline Mammary Carcinoma: A Tissue Microarray-Fluorescence In Situ Hydridization-Based Study

Human epidermal growth factor receptor 2 (HER2) is a tyrosine kinase receptor overexpressed in a subset of breast cancer due to HER2 gene amplification. HER2 protein is expressed in feline mammary carcinomas, but little is known about its cytogenetic alterations. The aim of this study was to evaluate HER2 gene amplification status and its correlation with HER2 protein expression in feline mammary carcinomas. Feline mammary carcinomas were retrospectively selected and immunohistochemically (IHC) evaluated for HER2 protein expression. All the HER2 IHC-positive (3+) and equivocal (2+) cases and a subset of negative cases (0/1+) were selected for fluorescence in situ hybridization (FISH). Dual-core tissue microarrays were prepared for FISH. IHC and FISH were evaluated according to the 2013 American Society of Clinical Oncology/College of American Pathologists guidelines. The study included 107 feline mammary carcinomas from 88 queens. HER2 protein expression was positive (3+) in 7 cases (6.5%), equivocal (2+) in 48 cases (45%), and negative (0/1+) in 52 cases (48.5%). HER2 status was indeterminate in 8 feline mammary carcinomas (12%), amplified in 3 (4%), equivocal in 4 (6%), and nonamplified in 53 (78%). HER2 gene amplification and protein expression were significantly positively correlated ( R = 0.283; P < .0001). HER2 gene is amplified in a subset of feline mammary carcinomas despite the HER2 positive or equivocal protein expression, but it remains to be determined if the HER2 amplification is a gene alteration that drives mammary tumor carcinogenesis or only a bystander passenger mutation.

Abstract 216: Functional stability, progression and evolution of targeted drug sensitivity of HER-2-positive breast cancer patient-derived xenografts

Human tumors are dynamic entities that undergo variation, selection and progression within the patient. How well patient-derived xenografts (PDX) recapitulate tumor dynamics? To investigate these aspects we established a collection of breast cancer PDX, representative of the main intrinsic subtypes. From 66 primary breast cancer specimens, we obtained 5 transplantable PDXs (8%). The highest rate of PDX stabilization was obtained for HER2-positive (40%) followed by triple negative (17%) and luminal B (14%) subtypes. In 3/66 cases a human lymphoma developed without any further evidence of breast cancer. Two HER-2-positive and one non-amplified, HER-2++, luminal B PDXs were serially transplanted in mice for 7-25 passages over a period of 2-4 years. Morphological and immunohistochemical (ER, PR, Ki67, p53, HER2, HER1, HER3, IGFR) features were highly stable over serial passages of PDXs, which retained the histology and the expression pattern of the tumor of origin. After the second passage, one HER-2++ amplified PDX, named BO-HAT4, was split in six different sublines, which were then studied separately to analyze random and selective events in long-term evolution. Two sublines progressively acquired a marked acceleration of tumor growth rate, whereas the remaining four did not. Metastatic spread was absent in early passages and appeared sporadically in late passages. In vitro cultures derived from early in vivo passages showed a rapid onset of cell senescence, whereas late in vivo passages gave rise to long-term in vitro cultures. However, we have not yet been able to obtain continuous cell lines from breast cancer PDX. To study the onset of resistance to HER-2 targeted therapies, sequential in vivo passages of BO-HAT4 were treated with trastuzumab, leading to a progressive loss of sensitivity. After one year of treatment BO-HAT4 was completely resistant to trastuzumab. We are currently investigating the molecular changes underlying trastuzumab resistance. Interestingly, both trastuzumab-sensitive and -resistant tumors were highly inhibited by neratinib. In conclusion, the low take rate as PDX prevents the generalized analysis of human breast cancer patients. Individual PDX allow the analysis of target therapy response and onset of resistance, however long-term study of transplantable breast cancer PDX show that tumor progression in these model systems is a late and random event. Supported by grants from the Italian Association for Cancer Research (AIRC) and the University of Bologna, Italy.

Citation Format: Lorena Landuzzi, Marianna L. Ianzano, Claudio Ceccarelli, Enrico Di Oto, Giordano Nicoletti, Veronica Giusti, Roberta Laranga, Tania Balboni, Carla De Giovanni, Massimiliano Dall'Ora, Sofia Asioli, Arianna Palladini, Donatella Santini, Maria Pia Foschini, Mario Taffurelli, Pier-Luigi Lollini, Patrizia Nanni. Functional stability, progression and evolution of targeted drug sensitivity of HER-2-positive breast cancer patient-derived xenografts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 216.

The role of clinical and molecular factors in low-grade gliomas: what is their impact on survival?

AIM

To evaluate relevance of clinical and molecular factors in adult low-grade gliomas (LGG) and to correlate with survival.

METHODS

We reviewed records from adult LGG patients from 1991 to 2015 who received surgery and had sufficient tissue to molecular biomarkers characterization.

RESULTS

213 consecutive LGG patients were included: 17.4% were low-risk, according to Radiation Therapy Oncology Group (RTOG) risk assessment. IDH 1/2 mutation, 1p/19q co-deletion, MGMT methylation were found in 93, 50.8 and 65.3% of patients. Median follow-up was 98.3 months. In univariate analysis, overall survival was influenced by extent of resection (p = 0.011), IDH mutation (p < 0.001), 1p/19q co-deletion (p = 0.015) and MGMT methylation (p = 0.013). In multivariate analysis, RTOG clinical risk (p = 0.006), IDH mutation (p < 0.001) and 1p/19q co-deletion (p = 0.035) correlated with overall survival. RTOG clinical risk (p = 0.006), IDH mutation (p < 0.001) and 1p/19q co-deletion (p = 0.035) correlated with overall survival.

CONCLUSION

Both clinical and molecular factors are essential to determine prognosis and treatment strategies.

Preferential expression of NY-BR-1 and GATA-3 in male breast cancer

BACKGROUND

Male breast cancer is an uncommon disease often discovered in advanced stage; thus, in the setting of metastatic adenocarcinoma, breast origin must be taken to account. Breast markers as NY-BR-1, GATA-3, mammaglobin, and BRST-2 are established tools for labelling primary and metastatic female breast cancer; however, none of them has been sufficiently studied in male breast cancer. The aim of this study was to analyze the expression of these markers in male breast cancer.

MATERIALS AND METHODS

Thirty consecutive cases of male breast cancer and eight loco-regional metastases were re-revaluated, assembled in tissue micro array (TMA), and stained with immunohistochemistry (IHC) for NY-BR-1, GATA-3, mammaglobin, and BRST-2. The IHC stains were scored either positive or negative. In addition, concordant expression patterns of primary tumors and matched metastasis were noted.

RESULTS

30 of 30 (100%) primary tumors and 8 of 8 (100%) metastases were positive for NY-BR-1. 30 of 30 (100%) primary tumors and 6 of 8 (75%) metastases were positive for GATA-3. 22 of 30 (73.3%) primary tumors and 6 of 8 (75%) metastases were positive for Mammaglobin. 18 of 30 (60%) primary tumors and 5 of 8 (62.5%) metastases were positive for BRST-2. Differences in staining percentage were not significant with Fisher's exact test.

CONCLUSION

We found a high sensitivity for all the markers analyzed. Moreover, the expression of NY-BR-1 and GATA-3 seemed the most effective for labelling male breast cancer in primary and metastatic setting.

Low grade glioma patients with IDH mutation and 1p19q codeletion: To treat or not to treat?

2017

Background: Molecular characterization of low grade gliomas (LGG) is essential for diagnosis and treatment of these diseases. LGG patients (pts) with IDH mutation and 1p19q codeletion (codel) are characterized by a median OS (mOS) longer than 10 years. Thus, the role of treatments and side effects should be carefully evaluated. Methods: We evaluated LGG pts from our data warehouse (n=679 pts) who received surgery and had sufficient tissue to assess biomarkers characterization. Pts with gliomatosis were excluded. IDH1/2 assessment was performed on formalin-fixed paraffin-embedded samples by qPCR. In wild type cases we performed NGS. 1p/19 codel analysis was performed by FISH. Results: 93 consecutive LGG with IDH mutation and codel were included. The median follow up (FU) was 96.1 months. Mean age was 40 yrs (range: 25-66); 8 pts (8.6%) underwent biopsy, 61 pts (65.6%) partial resection, 24 pts (25.8%) complete resection. 84 pts (90.3%) were considered high risk using RTOG criteria (>40 years and/or incomplete resection). Fifty pts (53.7%) received only FU, 17 pts (18.3%) received chemotherapy (CT), 18 pts (19.4%) received radiotherapy (RT), 8 pts (8.6%) received RT + CT. Median PFS (mPFS) was 59.6 months (95%CI: 41.8-77.4) and was significantly longer in pts who received postsurgical treatments (79.5 months, 95%CI: 66.4-92.7) than pts who received FU (46.3 months, 95%CI: 36.0-56.5; P=0.001). mPFS was 50.8 months (95%CI: 17.4-84.3), 103.6 months (95%CI: 11.7-195.6) and 120.2 months (95%CI: 40.5-199.8) in pts treated with CT alone, RT alone and RT + CT, respectively. Multivariate analysis showed that receiving a post-surgical treatment (P<0.001), and the extent of resection (P=0.043) were significantly correlated with PFS. Conclusions: Our study evaluated the role of treatments in LGG pts assessed with NGS and FISH. Post-surgical treatments are crucial to extend PFS in pts with IDH mutation and codel. The choice of post-surgical treatments seems to have a role, being CT alone less effective than RT and RT+CT. Longer FU is needed to provide information about OS.

HER2 isoforms co-expression differently tunes mammary tumor phenotypes affecting onset, vasculature and therapeutic response

Full-length HER2 oncoprotein and splice variant Delta16 are co-expressed in human breast cancer. We studied their interaction in hybrid transgenic mice bearing human full-length HER2 and Delta16 (F1 HER2/Delta16) in comparison to parental HER2 and Delta16 transgenic mice. Mammary carcinomas onset was faster in F1 HER2/Delta16 and Delta16 than in HER2 mice, however tumor growth was slower, and metastatic spread was comparable in all transgenic mice. Full-length HER2 tumors contained few large vessels or vascular lacunae, whereas Delta16 tumors presented a more regular vascularization with numerous endothelium-lined small vessels. Delta16-expressing tumors showed a higher accumulation of i.v. injected doxorubicin than tumors expressing full-length HER2. F1 HER2/Delta16 tumors with high full-length HER2 expression made few large vessels, whereas tumors with low full-length HER2 and high Delta16 contained numerous small vessels and expressed higher levels of VEGF and VEGFR2. Trastuzumab strongly inhibited tumor onset in F1 HER2/Delta16 and Delta16 mice, but not in full-length HER2 mice. Addiction of F1 tumors to Delta16 was also shown by long-term stability of Delta16 levels during serial transplants, in contrast full-length HER2 levels underwent wide fluctuations. In conclusion, full-length HER2 leads to a faster tumor growth and to an irregular vascularization, whereas Delta16 leads to a faster tumor onset, with more regular vessels, which in turn could better transport cytotoxic drugs within the tumor, and to a higher sensitivity to targeted therapeutic agents. F1 HER2/Delta16 mice are a new immunocompetent mouse model, complementary to patient-derived xenografts, for studies of mammary carcinoma onset, prevention and therapy.

X chromosome gain in male breast cancer

Male breast cancer (MBC) is an uncommon disease whose molecular profile is not well known. X chromosome gain has been described as a marker of aggressive behavior in female breast cancer. The aim of this study is to investigate the role of the X chromosome in male breast cancer. Twenty cases of male breast invasive ductal carcinoma were retrieved and compared with 10 cases of gynecomastia. Cases were tested by fluorescence in situ hybridization to assess a cytogenetic profile for the X chromosome. The X chromosome status was compared with histopathologic features and stage at presentation. All MBC cases harbored an X chromosome gain (100%) in a variable percentage of neoplastic cells, ranging from 31% to 85% (mean, 59%). On the contrary, all cases of gynecomastia showed wild X chromosome asset. The patients' age at surgery and tumor grading showed a statistically significant correlation (P = .0188-.04), with the percentages of neoplastic cells showing an X chromosome gain. These data suggest that this X chromosome gain plays a role in the neoplastic transformation of male breast epithelial cells.

Transplanted human adipose tissue-derived stem cells engraft and induce regeneration in mice olfactory neuroepithelium in response to dichlobenil subministration

We used immunodeficient mice, whose dorsomedial olfactory region was permanently damaged by dichlobenil inoculation, to test the neuroregenerative properties of transplanted human adipose tissue-derived stem cells after 30 and 60 days. Analysis of polymerase chain reaction bands revealed that stem cells preferentially engrafted in the lesioned olfactory epithelium compared with undamaged mucosa of untreated transplanted mice. Although basal cell proliferation in untransplanted lesioned mice did not give rise to neuronal cells in the olfactory mucosa, we observed clusters of differentiating olfactory cells in transplanted mice. After 30 days, and even more at 60 days, epithelial thickness was partially recovered to normal values, as also the immunohistochemical properties. Functional reactivity to odorant stimulation was also confirmed through electro-olfactogram recording in the dorsomedial epithelium. Furthermore, we demonstrated that engrafted stem cells fused with mouse cells in the olfactory organ, even if heterokaryons detected were too rare to hypothesize they directly repopulated the lesioned epithelium. The data reported prove that the migrating transplanted stem cells were able to induce a neuroregenerative process in a specific lesioned sensory area, enforcing the perspective that they could become an available tool for stem cell therapy.

Increased expression of pro-angiogenic factors and vascularization in thyroid hyperfunctioning adenomas with and without TSH receptor activating mutations

Autonomously functioning thyroid nodules (AFTN) are known to receive an increased blood influx necessary to sustain their high rate of growth and hormone production. Here, we investigated the expression of hematic and lymphatic vases in a series of 20 AFTN compared with the contralateral non-tumor tissues of the same patients, and the transcript levels of proteins involved in the control of vascular proliferation, including the vascular endothelial growth factor (VEGF) and platelet-derived growth factors (PDGF) and their receptors and the endothelial nitric oxide synthase (eNOS). In parallel, the expression of the differentiation markers sodium/iodide symporter (NIS), thyroperoxidase (TPO), thyroglobulin (Tg), and TSH receptor (TSHR) was also investigated. The data were further analyzed comparing subgroups of tumors with or without mutations in the TSHR gene. Analysis by means of CD31 and D2-40 immunostaining showed in AFTN an increased number of hematic, but not lymphatic, vessels in parallel with an enhanced proliferation rate shown by increased Ki67 staining. Quantitative RT-PCR analysis revealed an increase of VEGF, VEGFR1 and 2, PDGF-A, PDGF-B, and eNOS expression in tumor versus normal tissues. Also, higher transcript levels of NIS, TPO, and Tg were detected. Comparison of the two subgroups of samples revealed only few differences in the expression of the genes examined. In conclusion, these data demonstrate an increased expression of angiogenesis-related factors associated with an enhanced proliferation of hematic, but not lymphatic, vessels in AFTNs. In this context, the presence of TSHR mutations may only slightly influence the expression of pro-angiogenic growth factors.

Nogo-A: a useful marker for the diagnosis of oligodendroglioma and for identifying 1p19q codeletion

The differential diagnosis between oligodendrogliomas and other gliomas remains a critical issue. The aim of this study is to verify the diagnostic value of Olig-2, Nogo-A, and synaptophysin and their role in identifying 1p19q codeletion. A total of 168 cases of brain tumors were studied: 24 oligodendrogliomas, 23 anaplastic oligodendrogliomas, 2 oligoastrocytomas, 2 anaplastic oligoastrocytomas, 30 glioblastoma multiforme, 2 diffuse astrocytomas, 4 anaplastic astrocytomas, 10 pilocytic astrocytomas, 9 ependymomas, 12 anaplastic ependymomas, 10 central neurocytomas, 10 meningiomas, 10 choroid plexus papillomas, 10 dysembryoplastic neuroepithelial tumors, and 10 metastases. All cases were immunostained with Olig-2, Nogo-A, and synaptophysin. In 79 cases, the status of 1p/19q had already been assessed by fluorescence in situ hybridization. Thus, in selected cases, fluorescence in situ hybridization was repeated in areas with numerous Nogo-A-positive neoplastic cells. Nogo-A was positive in 18 (75%) of 24 oligodendrogliomas, 8 (80%) of 10 dysembryoplastic neuroepithelial tumors, 6 (20%) of 30 glioblastoma multiforme, and 2 (20%) of 10 pilocytic astrocytomas. Olig-2 stained 22 (91.6%) of 24 oligodendrogliomas and all dysembryoplastic neuroepithelial tumors but also 24 (80%) of 30 glioblastoma multiforme and 8 (80%) of 10 pilocytic astrocytomas. Finally, synaptophysin stained 13 (54.1%) of 24 oligodendrogliomas, 3 (10%) of 30 glioblastoma multiforme, 1 (10%) of 10 pilocytic astrocytomas, and all neurocytomas. Among the 79 tested cases, original fluorescence in situ hybridization showed 1p/19q codeletion in 12 (52.2%) of 23 oligodendrogliomas, 8 (38%) of 21 anaplastic oligodendrogliomas, and 1 (4%) of 25 glioblastoma multiforme. However, after carrying out the Nogo-A-driven fluorescence in situ hybridization, 1p/19q codeletion was observed in 8 additional cases. Nogo-A is more useful and specific than Olig-2 in differentiating oligodendrogliomas from other gliomas. Furthermore, using a Nogo-A-driven fluorescence in situ hybridization analysis, it is possible to identify a larger number of 1p19q codeletions in gliomas.

Genetic activation of the MET pathway and prognosis of patients with high-risk, radically resected gastric cancer

PURPOSE

To investigate whether prognosis of patients with high-risk gastric cancer may depend on MET copy number gain (CNG) or an activating truncation within a deoxyadenosine tract element (DATE) in the promoter region of the MET ligand HGF.

PATIENTS AND METHODS

A single-institution cohort of 230 patients with stage II/III gastric cancer was studied. Formalin-fixed paraffin-embedded tumor specimens were used for DNA extraction. Quantitative polymerase chain reaction (qPCR) for MET CNG and sequencing for HGF DATE truncation (< 25 deoxyadenosines instead of 30) were used. Results were analyzed for association with disease-free survival (DFS) and overall survival (OS). To assess the reliability of the qPCR measurement, a random sample of cases was reanalyzed using an alternative assay (fluorescent in situ hybridization [FISH]) with calculation of the intracorrelation coefficient (ICC).

RESULTS

In 216 assessable patients, MET CNG five or more copies and homozygous HGF-truncated DATE occurred in 21 patients (10%) and 30 patients (13%), respectively. Patients with MET CNG five or more copies (MET-positive) showed significantly worse prognosis with multivariate hazard ratio (HR) of 3.02 (95% CI, 1.71 to 5.33; P < .001) for DFS and multivariate HR of 2.91 (95% CI, 1.65 to 5.11; P < .001) for OS. The agreement between qPCR and FISH was high, with ICC = 0.9% (95% CI, 0.81% to 0.95%; the closer the ICC is to 1, the greater is the agreement). HGF-truncated DATE did not show relevant prognostic effect.

CONCLUSION

In this study, qPCR revealed approximately 10% of white patients with gastric cancer harboring MET CNG of five or more copies. This marker was significantly associated with unfavorable prognosis. This information is relevant to the current clinical development of anti-MET compounds.