title: Targeted vaccination against the bevacizumab binding site on VEGF using 3D-structured peptides elicits efficient antitumor activity.
abstract: Therapeutic targeting of the VEGF signaling axis by the VEGF-neutralizing monoclonal antibody bevacizumab has clearly demonstrated clinical benefit in cancer patients. To improve this strategy using a polyclonal approach, we developed a vaccine targeting VEGF using 3D-structured peptides that mimic the bevacizumab binding site. An in-depth study on peptide optimization showed that the antigen's 3D structure is essential to achieve neutralizing antibody responses. Peptide 1 adopts a clear secondary, native-like structure, including the typical cysteine-knot fold, as evidenced by CD spectroscopy. Binding and competition studies with bevacizumab in ELISA and surface plasmon resonance analysis revealed that peptide 1 represents the complete bevacizumab binding site, including the hairpin loop (β5-turn-β6) and the structure-supporting β2-α2-β3 loop. Vaccination with peptide 1 elicited high titers of cross-reactive antibodies to VEGF, with potent neutralizing activity. Moreover, vaccination-induced antisera displayed strong angiostatic and tumor-growth-inhibiting properties in a preclinical mouse model for colorectal carcinoma, whereas antibodies raised with peptides exclusively encompassing the β5-turn-β6 loop (peptides 15 and 20) did not. Immunization with peptide 1 or 7 (murine analog of 1) in combination with the potent adjuvant raffinose fatty acid sulfate ester (RFASE) showed significant inhibition of tumor growth in the B16F10 murine melanoma model. Based on these data, we conclude that this vaccination technology, which is currently being investigated in a phase I clinical trial (NCT02237638), can potentially outperform currently applied anti-VEGF therapeutics.
authors: Angiogenesis Laboratory, Department of Medical Oncology, Vrije Universiteit Medical Center, 1081 HZ Amsterdam, The Netherlands.
authors: Madelon Q
authors: 0000-0002-2592-298X
authors: MQ
authors: Wentink
authors: Department of Biochemistry, Maastricht University Medical Center, 6229 HX Maastricht, The Netherlands.
authors: Tilman M
authors: TM
authors: Hackeng
authors: Angiogenesis Laboratory, Department of Medical Oncology, Vrije Universiteit Medical Center, 1081 HZ Amsterdam, The Netherlands.
authors: Sebastien P
authors: SP
authors: Tabruyn
authors: Pepscan Therapeutics B.V., 8243 RC Lelystad, The Netherlands.
authors: Wouter C
authors: WC
authors: Puijk
authors: Pepscan Therapeutics B.V., 8243 RC Lelystad, The Netherlands.
authors: Klaus
authors: K
authors: Schwamborn
authors: Equipe labellisée Ligue 2015, UMR 7242, Université de Strasbourg, CNRS, École Supérieure de Biotechnologie de Strasbourg, 67412 Illkirch, France.
authors: Daniele
authors: D
authors: Altschuh
authors: Pepscan Therapeutics B.V., 8243 RC Lelystad, The Netherlands.
authors: Rob H
authors: RH
authors: Meloen
authors: Animal Sciences Group, Wageningen University and Research, 6708 WD Wageningen, Lelystad, The Netherlands.
authors: Teun
authors: T
authors: Schuurman
authors: Angiogenesis Laboratory, Department of Medical Oncology, Vrije Universiteit Medical Center, 1081 HZ Amsterdam, The Netherlands; p.timmerman@pepscan.com aw.griffioen@vumc.nl.
authors: Arjan W
authors: AW
authors: Griffioen
authors: Pepscan Therapeutics B.V., 8243 RC Lelystad, The Netherlands; p.timmerman@pepscan.com aw.griffioen@vumc.nl.|Van't Hoff Institute of Molecular Sciences, University of Amsterdam, 1098 HX Amsterdam, The Netherlands.
authors: Peter
authors: P
authors: Timmerman
mesh_terms: D000595:Amino Acid Sequence; D020533:Angiogenesis Inhibitors / Q000276:immunology / Q000627:therapeutic use; D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology; D000068258:Bevacizumab / Q000276:immunology / Q000627:therapeutic use*; D001665:Binding Sites / Q000276:immunology; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000276:immunology; D003429:Cross Reactions / Q000276:immunology; D006801:Humans; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D058990:Molecular Targeted Therapy / Q000379:methods; D010455:Peptides / Q000737:chemistry / Q000276:immunology / Q000627:therapeutic use*; D017208:Rats, Wistar; D014611:Vaccination / Q000379:methods*; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors* / Q000276:immunology; D023041:Xenograft Model Antitumor Assays
chemical_list: D020533:Angiogenesis Inhibitors; D057134:Antibodies, Neutralizing; D010455:Peptides; D042461:Vascular Endothelial Growth Factor A; D000068258:Bevacizumab
keywords: VEGF; angiogenesis; immunization; peptide vaccines; protein mimicry