title: Oncogenic HER2 fusions in gastric cancer.
abstract: BACKGROUND
  Genetic amplification of HER2 drives tumorigenesis and cancer progression in a subset of patients with gastric cancer (GC), and treatment with trastuzumab, a humanized HER2-neutralizing antibody, improves the overall survival rate of HER2-positive patients. However, a considerable portion of the patients does not respond to trastuzumab and the molecular mechanisms underlying the intrinsic resistance to anti-HER2 therapy in GC is not fully understood.
  
  
  METHODS
  We performed whole-transcriptome sequencing on 21 HER2-positive tumor specimens from Chinese GC patients. Whole genome sequencing was performed on the three samples with HER2 fusion to discover the DNA integration structure. A multicolor FISH assay for HER2 split screening was conducted to confirm HER2 fusion and IHC (HercepTest™) was used to detect the membranous expression of HER2. Fusion cDNA were transfected into NIH/3T3 cells and generate stable cell line by lentivirus. The expression of exogenous HER2 fusion proteins and pHER2 were examined by western blot analysis. In vitro efficacy studies were also conducted by PD assay and softagar assay in cell line expression wild type and fusion HER2. T-DM1 was used to assess its binding to NIH/3T3 cells ectopically expressing wild-type and fusion HER2. Finally, the anti-tumor efficacy of trastuzumab was tested in NIH/3 T3 xenografts expressing the HER2 fusion variants.
  
  
  RESULTS
  We identified three new HER2 fusions with ZNF207, MDK, or NOS2 in 21 HER2-amplified GC samples (14%; 3/21). Two of the fusions, ZNF207-HER2, and MDK-HER2, which are oncogenic, lead to aberrant activation of HER2 kinase. Treatment with trastuzumab inhibited tumor growth significantly in xenografts expressing MDK-HER2 fusion. In contrast, trastuzumab had no effect on the growth of xenografts expressing ZNF207-HER2 fusion, due to its inability to bind to trastuzumab.
  
  
  CONCLUSIONS
  Our results provide the molecular basis of a novel resistance mechanism to trastuzumab-based anti-HER2 therapy, supporting additional molecule stratification within HER2-positive GC patients for more effective therapy options.
authors.affiliation: Innovation Center China, Asia & Emerging Market iMed, AstraZeneca Innovation Medicines and Early Development, 199 Liangjing Road, Zhangjiang Hi-Tech Park, Shanghai, 201203, China. yudehua@yahoo.com.
authors.forename: De-Hua
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authors.lastname: Yu
authors.affiliation: Innovation Center China, Asia & Emerging Market iMed, AstraZeneca Innovation Medicines and Early Development, 199 Liangjing Road, Zhangjiang Hi-Tech Park, Shanghai, 201203, China. lily.tang@astrazeneca.com.
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authors.affiliation: Innovation Center China, Asia & Emerging Market iMed, AstraZeneca Innovation Medicines and Early Development, 199 Liangjing Road, Zhangjiang Hi-Tech Park, Shanghai, 201203, China. hua.dong@astrazeneca.com.
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authors.affiliation: Innovation Center China, Asia & Emerging Market iMed, AstraZeneca Innovation Medicines and Early Development, 199 Liangjing Road, Zhangjiang Hi-Tech Park, Shanghai, 201203, China. harvey.dong@astrazeneca.com.
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authors.affiliation: Key laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Surgery, Peking University Cancer Hospital and Institute, Beijing, China. zlhzlh@hotmail.com.
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authors.affiliation: Innovation Center China, Asia & Emerging Market iMed, AstraZeneca Innovation Medicines and Early Development, 199 Liangjing Road, Zhangjiang Hi-Tech Park, Shanghai, 201203, China. jiangang.fu@astrazeneca.com.
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authors.affiliation: Innovation Center China, Asia & Emerging Market iMed, AstraZeneca Innovation Medicines and Early Development, 199 Liangjing Road, Zhangjiang Hi-Tech Park, Shanghai, 201203, China. xinying.su@astrazeneca.com.
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authors.affiliation: Innovation Center China, Asia & Emerging Market iMed, AstraZeneca Innovation Medicines and Early Development, 199 Liangjing Road, Zhangjiang Hi-Tech Park, Shanghai, 201203, China. tianwei.zhang@astrazeneca.com.
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authors.affiliation: Innovation Center China, Asia & Emerging Market iMed, AstraZeneca Innovation Medicines and Early Development, 199 Liangjing Road, Zhangjiang Hi-Tech Park, Shanghai, 201203, China. haihua.fu@astrazeneca.com.
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authors.affiliation: Innovation Center China, Asia & Emerging Market iMed, AstraZeneca Innovation Medicines and Early Development, 199 Liangjing Road, Zhangjiang Hi-Tech Park, Shanghai, 201203, China. luna.han@astrazeneca.com.
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authors.affiliation: Innovation Center China, Asia & Emerging Market iMed, AstraZeneca Innovation Medicines and Early Development, 199 Liangjing Road, Zhangjiang Hi-Tech Park, Shanghai, 201203, China. xieliang_02@yahoo.com.
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authors.affiliation: Department of General Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China. hyschen@163.com.
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authors.affiliation: Innovation Center China, Asia & Emerging Market iMed, AstraZeneca Innovation Medicines and Early Development, 199 Liangjing Road, Zhangjiang Hi-Tech Park, Shanghai, 201203, China. zl_qian@aliyun.com.
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authors.affiliation: Innovation Center China, Asia & Emerging Market iMed, AstraZeneca Innovation Medicines and Early Development, 199 Liangjing Road, Zhangjiang Hi-Tech Park, Shanghai, 201203, China. guanshan_zhu@hotmail.com.
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authors.affiliation: Innovation Center China, Asia & Emerging Market iMed, AstraZeneca Innovation Medicines and Early Development, 199 Liangjing Road, Zhangjiang Hi-Tech Park, Shanghai, 201203, China. jia.wang@astrazeneca.com.
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authors.affiliation: Innovation Center China, Asia & Emerging Market iMed, AstraZeneca Innovation Medicines and Early Development, 199 Liangjing Road, Zhangjiang Hi-Tech Park, Shanghai, 201203, China. jingchuanzhang@yahoo.com.
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authors.affiliation: Innovation Center China, Asia & Emerging Market iMed, AstraZeneca Innovation Medicines and Early Development, 199 Liangjing Road, Zhangjiang Hi-Tech Park, Shanghai, 201203, China. lucy.yin@astrazeneca.com.
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authors.affiliation: Innovation Center China, Asia & Emerging Market iMed, AstraZeneca Innovation Medicines and Early Development, 199 Liangjing Road, Zhangjiang Hi-Tech Park, Shanghai, 201203, China. xiaolin.zhang@astrazeneca.com.
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authors.affiliation: Innovation Center China, Asia & Emerging Market iMed, AstraZeneca Innovation Medicines and Early Development, 199 Liangjing Road, Zhangjiang Hi-Tech Park, Shanghai, 201203, China. qsji18@yahoo.com.|Current mailing address: WuXi AppTec, 288 Fute Zhong Road, Waigaoqiao, China (Shanghai) Pilot Free Trade Zone, Shanghai, 200131, China. qsji18@yahoo.com.
authors.forename: Qunsheng
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mesh_terms: D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D050939:Gene Fusion; D018734:Genes, erbB-2; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D051379:Mice; D041681:NIH 3T3 Cells; D009857:Oncogenes; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000235:genetics*
chemical_list: D017931:DNA Primers