title: (89)Zr-trastuzumab PET visualises HER2 downregulation by the HSP90 inhibitor NVP-AUY922 in a human tumour xenograft.
abstract: NVP-AUY922, a potent heat shock protein (HSP) 90 inhibitor, downregulates the expression of many oncogenic proteins, including the human epidermal growth factor receptor-2 (HER2). Because HER2 downregulation is a potential biomarker for early response to HSP90-targeted therapies, we used the (89)Zr-labelled HER2 antibody trastuzumab to quantify the alterations in HER2 expression after NVP-AUY922 treatment with HER2 positron emission tomography (PET) imaging. The HER2 overexpressing human SKOV-3 ovarian tumour cell line was used for in vitro experiments and as xenograft model in nude athymic mice. In vitro HER2 membrane expression was assessed by flow cytometry and a radio-immuno assay with (89)Zr-trastuzumab. For in vivo evaluation, mice received 50mg/kg NVP-AUY922 intraperitoneally every other day. (89)Zr-trastuzumab was injected intravenously 6d before NVP-AUY922 treatment and after 3 NVP-AUY922 doses. MicroPET imaging was performed at 24, 72 and 144h post tracer injection followed by ex-vivo biodistribution and immunohistochemical staining. After 24h NVP-AUY922 treatment HER2 membrane expression showed profound reduction with flow cytometry (80%) and radio-immuno assay (75%). PET tumour quantification, showed a mean reduction of 41% (p=0.0001) in (89)Zr-trastuzumab uptake at 144h post tracer injection after NVP-AUY922 treatment. PET results were confirmed by ex-vivo (89)Zr-trastuzumab biodistribution and HER2 immunohistochemical staining. NVP-AUY922 effectively downregulates HER2, which can be monitored and quantified in vivo non-invasively with (89)Zr-trastuzumab PET. This technique is currently under clinical evaluation and might serve as an early biomarker for HSP90 inhibition in HER2 positive metastatic breast cancer patients.
authors.affiliation: Department of Medical Oncology, University of Groningen and University Medical Centre Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.
authors.forename: Thijs H
authors.initials: TH
authors.lastname: Oude Munnink
authors.forename: Maarten A de
authors.initials: MA
authors.lastname: Korte
authors.forename: Wouter B
authors.initials: WB
authors.lastname: Nagengast
authors.forename: Hetty
authors.initials: H
authors.lastname: Timmer-Bosscha
authors.forename: Carolina P
authors.initials: CP
authors.lastname: Schröder
authors.forename: Johan R de
authors.initials: JR
authors.lastname: Jong
authors.forename: Guus A M S van
authors.initials: GA
authors.lastname: Dongen
authors.forename: Michael Rugaard
authors.initials: MR
authors.lastname: Jensen
authors.forename: Cornelia
authors.initials: C
authors.lastname: Quadt
authors.forename: Marjolijn N Lub-de
authors.initials: MN
authors.lastname: Hooge
authors.forename: Elisabeth G E de
authors.initials: EG
authors.lastname: Vries
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D014408:Biomarkers, Tumor / Q000096:biosynthesis*; D015536:Down-Regulation / Q000187:drug effects; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors*; D006801:Humans; D007555:Isoxazoles / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008819:Mice, Nude; D010051:Ovarian Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D049268:Positron-Emission Tomography / Q000379:methods; D011868:Radioisotopes; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000096:biosynthesis*; D012118:Resorcinols / Q000494:pharmacology*; D000068878:Trastuzumab; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays; D015040:Zirconium
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D014408:Biomarkers, Tumor; D018841:HSP90 Heat-Shock Proteins; D007555:Isoxazoles; D011868:Radioisotopes; D018719:Erb-b2 Receptor Tyrosine Kinases; D012118:Resorcinols; D000068878:Trastuzumab; D015040:Zirconium; C528044:5-(2,4-dihydroxy-5-isopropylphenyl)-4-(4-morpholin-4-ylmethylphenyl)isoxazole-3-carboxylic acid ethylamide; C508053:ERBB2 protein, human