title: Metronomic treatment of malignant glioma xenografts with irinotecan (CPT-11) inhibits angiogenesis and tumor growth.
abstract: Irinotecan (CPT-11) has shown emerging promise in the treatment of malignant gliomas. It is believed the mechanism of action of irinotecan is to sensitize glioma cells to the cytotoxic action of radiation therapy and alkylating agents. However, clinical trials using weekly or three-weekly doses of CPT-11 have demonstrated imaging responses in only 10-15% of patients. In this study, we evaluated another mechanism of action, angiosuppression by CPT-11 of ACNU-resistant gliomas, using a metronomic administration schedule. Two different types of treatment, (1) conventional and (2) metronomic, were applied to the subcutaneous U87 model. We found that metronomic administration of CPT-11 significantly inhibited malignant glioma growth by inhibiting angiogenesis; this treatment procedure reduced the number of tumor vessels and the area of hypoxic lesions and reduced expression of VEGF and HIF-1alpha, the most important angiogenic factors in gliomas. Metronomic treatment was superior to conventional treatment with regard to the severe systemic side effect of body weight loss. The growth inhibitory effect was very similar for both low and high doses of CPT-11. These angiosuppressive effects of CPT-11 show promise for another use of CPT-11 in metronomic and scheduled angiosuppressive chemotherapy with low dose and long-term administration for malignant gliomas without systemic side effects.
authors.affiliation: Department of Neurosurgery, Institute of Clinical Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba city, Ibaraki 305-8575, Japan. shingo4@md.tsukuba.ac.jp
authors.forename: Shingo
authors.initials: S
authors.lastname: Takano
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kamiyama
authors.forename: Ryota
authors.initials: R
authors.lastname: Mashiko
authors.forename: Satoru
authors.initials: S
authors.lastname: Osuka
authors.forename: Eiichi
authors.initials: E
authors.lastname: Ishikawa
authors.forename: Akira
authors.initials: A
authors.lastname: Matsumura
mesh_terms: D020533:Angiogenesis Inhibitors / Q000627:therapeutic use; D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000627:therapeutic use*; D001932:Brain Neoplasms / Q000098:blood supply / Q000473:pathology / Q000517:prevention & control*; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000627:therapeutic use; D049109:Cell Proliferation / Q000187:drug effects*; D005910:Glioma / Q000098:blood supply / Q000473:pathology / Q000517:prevention & control*; D000860:Hypoxia / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D007124:Immunoenzyme Techniques; D000077146:Irinotecan; D008297:Male; D051379:Mice; D016513:Mice, SCID; D009389:Neovascularization, Pathologic / Q000517:prevention & control*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015996:Survival Rate; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
chemical_list: D020533:Angiogenesis Inhibitors; D000972:Antineoplastic Agents, Phytogenic; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D000077146:Irinotecan; D002166:Camptothecin