title: Dual targeting of Angiopoetin-2 and VEGF potentiates effective vascular normalisation without inducing empty basement membrane sleeves in xenograft tumours.
abstract: BACKGROUND
  Effective vascular normalisation following vascular endothelial growth factor (VEGF) inhibition is associated with endothelial cell regression leaving empty basement membrane sleeves (BMS). These long-lived BMS permit the rapid regrowth of tumour vasculature upon treatment cessation and promote resistance to VEGF-targeting drugs. Previous attempts at removing BMS have failed. Angiopoietin-2 (Ang2) is a vascular destabilizing factor that antagonises normalisation. We hypothesised that Ang2 inhibition could permit vascular normalisation at significantly reduced doses of VEGF inhibition, avoiding excessive vessel regression and the formation of empty BMS.
  
  
  METHODS
  Mice xenografted with human colorectal cancer cells (LS174T) were treated with low (0.5 mg kg(-1)) or high (5 mg kg(-1)) doses of the VEGF-targeting antibody bevacizumab with or without an Ang2 blocking peptibody L1-10. Tumour growth, BMS formation and normalisation parameters were examined including vessel density, pericyte coverage, adherence junctions, leakiness, perfusion, hypoxia and proliferation.
  
  
  RESULTS
  Dual targeting of VEGF and Ang2 achieved effective normalisation at only one-tenth of the dose required with bevacizumab alone. Pericyte coverage, vascular integrity, adherence junctions and perfusion as prerequisites for improved access of chemotherapy were improved without inducing empty BMS that facilitate rapid vascular regrowth.
  
  
  CONCLUSIONS
  Dual targeting of VEGF and Ang2 can potentiate the effectiveness of VEGF inhibitors and avoid the formation of empty BMS.
authors.affiliation: Department I for Internal Medicine, University of Cologne, Kerpener Strasse 62, 50924 Cologne, Germany.
authors.forename: O
authors.initials: O
authors.lastname: Coutelle
authors.affiliation: Department I for Internal Medicine, University of Cologne, Kerpener Strasse 62, 50924 Cologne, Germany.
authors.forename: L M
authors.initials: LM
authors.lastname: Schiffmann
authors.affiliation: Department I for Internal Medicine, University of Cologne, Kerpener Strasse 62, 50924 Cologne, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Liwschitz
authors.affiliation: Department I for Internal Medicine, University of Cologne, Kerpener Strasse 62, 50924 Cologne, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Brunold
authors.affiliation: 1] Department I for Internal Medicine, University of Cologne, Kerpener Strasse 62, 50924 Cologne, Germany [2] Deptartment for Geriatric Care, St Marien Hospital, Kunibertskloster 11-13, 50668 Cologne, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Goede
authors.affiliation: Department I for Internal Medicine, University of Cologne, Kerpener Strasse 62, 50924 Cologne, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Hallek
authors.affiliation: 1] Institute for Medical Microbiology, Immunology and Hygiene, Medical Faculty, University of Cologne, Goldenfelsstraße 19-21, 50935 Cologne, Germany [2] Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Medical Faculty, University of Cologne, Robert-Koch-Straße 39, 50931 Cologne, Germany [3] Center for Molecular Medicine Cologne (CMMC), Robert-Koch-Straße 39, 50931 Cologne, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Kashkar
authors.affiliation: 1] Department I for Internal Medicine, University of Cologne, Kerpener Strasse 62, 50924 Cologne, Germany [2] University Cancer Center Leipzig, Liebigstraße 20, 04103 Leipzig, Germany.
authors.forename: U T
authors.initials: UT
authors.lastname: Hacker
mesh_terms: D042702:Angiopoietin-2 / Q000037:antagonists & inhibitors*; D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000008:administration & dosage; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D001485:Basement Membrane / Q000187:drug effects* / Q000473:pathology; D000068258:Bevacizumab; D001808:Blood Vessels / Q000187:drug effects / Q000473:pathology; D003110:Colonic Neoplasms / Q000098:blood supply / Q000188:drug therapy* / Q000473:pathology; D004357:Drug Synergism; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D058990:Molecular Targeted Therapy / Q000379:methods; D009389:Neovascularization, Pathologic / Q000517:prevention & control*; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors*; D023041:Xenograft Model Antitumor Assays
chemical_list: D042702:Angiopoietin-2; D061067:Antibodies, Monoclonal, Humanized; D011993:Recombinant Fusion Proteins; D042461:Vascular Endothelial Growth Factor A; C539318:peptibody A; D000068258:Bevacizumab