title: Increased antitumor activity of bevacizumab in combination with hypoxia inducible factor-1 inhibition.
abstract: Inhibition of hypoxia inducible factor-1 (HIF-1) is an attractive therapeutic strategy to target the tumor microenvironment. However, HIF-1 inhibitors may have limited activity as single agents and combination therapies may be required. We tested the hypothesis that HIF-1 inhibition in a hypoxic-stressed tumor microenvironment, which could be generated by administration of antiangiogenic agents, may result in a more pronounced therapeutic effect. The activity of bevacizumab, either alone or in combination with the HIF-1alpha inhibitor topotecan, was evaluated in U251-HRE xenografts. Tumor tissue was collected at the end of treatment and changes in tumor oxygenation, angiogenesis, proliferation, apoptosis, HIF-1alpha levels, HIF-1 target genes, and DNA damage were evaluated. Bevacizumab decreased microvessel-density and increased intratumor-hypoxia, but did not induce apoptosis. Moreover, bevacizumab alone caused a significant increase of HIF-1-dependent gene expression in tumor tissue. Addition of a low dose of daily topotecan to bevacizumab significantly inhibited tumor growth, relative to mice treated with topotecan or bevacizumab alone (P < 0.01). The addition of topotecan to bevacizumab was also associated with profound inhibition of HIF-1 transcriptional activity, significant inhibition of proliferation, and induction of apoptosis. Importantly, DNA damage induced by topotecan alone was not augmented by addition of bevacizumab, suggesting that increased cytotoxic activity did not account for the increased antitumor effects observed. These results strongly suggest that combination of anti-vascular endothelial growth factor antibodies with HIF-1 inhibitors is an attractive therapeutic strategy targeting in the hypoxic tumor microenvironment.
authors: SAIC-Frederick Inc, National Cancer Institue at Frederick, Frederick, MD 21702, USA.
authors: Annamaria
authors: A
authors: Rapisarda
authors: Melinda
authors: M
authors: Hollingshead
authors: Badarch
authors: B
authors: Uranchimeg
authors: Carrie A
authors: CA
authors: Bonomi
authors: Suzanne D
authors: SD
authors: Borgel
authors: John P
authors: JP
authors: Carter
authors: Bradley
authors: B
authors: Gehrs
authors: Mark
authors: M
authors: Raffeld
authors: Robert J
authors: RJ
authors: Kinders
authors: Ralph
authors: R
authors: Parchment
authors: Miriam R
authors: MR
authors: Anver
authors: Robert H
authors: RH
authors: Shoemaker
authors: Giovanni
authors: G
authors: Melillo
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D061067:Antibodies, Monoclonal, Humanized; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D000068258:Bevacizumab; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000469:parasitology / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects; D004249:DNA Damage / Q000187:drug effects; D004357:Drug Synergism; D005260:Female; D005910:Glioma / Q000098:blood supply / Q000188:drug therapy* / Q000473:pathology; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors*; D007124:Immunoenzyme Techniques; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D009389:Neovascularization, Pathologic / Q000517:prevention & control; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019772:Topotecan / Q000008:administration & dosage; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D014408:Biomarkers, Tumor; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; D000068258:Bevacizumab; D019772:Topotecan; D008156:Luciferases