title: Neoadjuvant treatment of colorectal cancer with bevacizumab: the perioperative angiogenic balance is sensitive to systemic thrombospondin-1 levels.
abstract: OBJECTIVE
  Colorectal cancer patients receiving neoadjuvant treatment with bevacizumab, a monoclonal antibody neutralizing vascular endothelial growth factor (VEGF), may suffer from wound healing complications after surgery as the antibody persists in patient blood. We characterized the systemic angiogenic balance in the perioperative period to evaluate its effect on physiologic angiogenesis.
  
  
  METHODS
  Nineteen patients receiving combination chemotherapy and bevacizumab for six neoadjuvant cycles were compared with 14 patients receiving chemotherapy without bevacizumab. Plasma from perioperative days -1, +1, +7, and +21 was analyzed for VEGF, thrombospondin-1 (TSP-1), and PD-ECGF concentrations. The angiogenic capacity was further tested in an in vitro assay of endothelial cell proliferation and migration.
  
  
  RESULTS
  On day +1, the onset of wound healing was reflected in a change of balance, i.e., an increase of proangiogenic factors VEGF and platelet-derived endothelial cell growth factor compared with low TSP-1 inhibitor levels in both treatment groups. Patients with bevacizumab therapy showed significantly higher blood levels of total VEGF throughout the evaluation period. However, most VEGF molecules were inactive, i.e., complexed with antibody. Nevertheless, the capacity to stimulate endothelial growth was higher for these plasma samples and was reflected in low TSP-1 levels and an altered TSP-1 sensitivity. When purified TSP-1 protein was added, plasma samples of the bevacizumab but not the chemotherapy group showed reduced endothelial growth.
  
  
  CONCLUSIONS
  Feedback mechanisms of bevacizumab therapy are not restricted to VEGF expression but seem to involve additional factors, such as TSP-1, which influences the systemic angiogenic balance and permits endothelial growth.
authors.affiliation: Medical University of Vienna, Department of Surgery, General Hospital, Vienna, Austria. Christine.Brostjan@meduniwien.ac.at
authors.forename: Christine
authors.initials: C
authors.lastname: Brostjan
authors.forename: Kristina
authors.initials: K
authors.lastname: Gebhardt
authors.forename: Birgit
authors.initials: B
authors.lastname: Gruenberger
authors.forename: Verena
authors.initials: V
authors.lastname: Steinrueck
authors.forename: Halina
authors.initials: H
authors.lastname: Zommer
authors.forename: Harald
authors.initials: H
authors.lastname: Freudenthaler
authors.forename: Sebastian
authors.initials: S
authors.lastname: Roka
authors.forename: Thomas
authors.initials: T
authors.lastname: Gruenberger
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D020533:Angiogenesis Inhibitors / Q000627:therapeutic use*; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D000068258:Bevacizumab; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000601:surgery; D042783:Endothelial Cells / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D019700:Thrombospondin 1 / Q000097:blood / Q000187:drug effects*; D013939:Thymidine Phosphorylase / Q000097:blood / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000097:blood / Q000187:drug effects; D014945:Wound Healing / Q000187:drug effects*
chemical_list: D020533:Angiogenesis Inhibitors; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D019700:Thrombospondin 1; D042461:Vascular Endothelial Growth Factor A; D000068258:Bevacizumab; D013939:Thymidine Phosphorylase