title: Neovascular targeting with cyclic RGD peptide (cRGDf-ACHA) to enhance delivery of radioimmunotherapy.
abstract: Radioimmunotherapy (RIT) has been hampered by delivery of only a small fraction of the administered dose of radiolabeled MAb to tumor. A strategy for creating and controlling tumor vascular permeability would enable more effective RIT. The alpha v beta 3 integrin receptor is an appealing target for strategies designed to enhance permeability of tumor vessels because it is highly and preferentially expressed in most tumors. In human tumor mouse models, apoptosis of neovascular endothelial cells has been demonstrated after treatment with alpha v beta 3 antagonists. Since this apoptotic effect could transiently increase permeability of tumor blood vessels, radiolabeled antibodies (MAb) circulating during this period would have increased access to extravascular tumor. To determine if this hypothesis was correct, a pharmacokinetic study of an immunospecific MAb given after an alpha v beta 3 antagonist was performed in nude mice bearing human breast cancer xenografts. The alpha v beta 3 antagonist, cyclic RGD pentapeptide (c-RGDf-ACHA; cyclo arginine glycine aspartic acid D-phenylalanine -1 amino cyclohexane carboxylic acid), inhibits alpha v beta 3 binding to its vitronectin ligand at nanomolar levels. Cyclic RGD peptide (250 micrograms i.p.) given 1 hour before 111In-ChL6 MAb resulted in a 40-50% increase in tumor uptake (concentration), when compared to the control tumor uptake, of MAb 24 hours after administration. When cyclic RGD peptide was given as a continuous infusion (17.5 micrograms/hr) for 1 or 24 hours before 111In-ChL6, tumor uptake of 111In-ChL6 was increased less, and, these data were not statistically different from the control data. There were no differences for any of the groups in the groups in the concentrations of 111In-ChL6 in normal organs or blood when compared to the control group. The results suggest that cyclic RGD peptide provided a temporary, selective increase in tumor vascular permeability, that allowed a larger fraction of the 111In-ChL6 to accumulate in the tumor.
authors.affiliation: Department of Internal Medicine, University of California Davis Medical Center, Sacramento, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: DeNardo
authors.forename: P A
authors.initials: PA
authors.lastname: Burke
authors.forename: B R
authors.initials: BR
authors.lastname: Leigh
authors.forename: R T
authors.initials: RT
authors.lastname: O'Donnell
authors.forename: L A
authors.initials: LA
authors.lastname: Miers
authors.forename: L A
authors.initials: LA
authors.lastname: Kroger
authors.forename: S L
authors.initials: SL
authors.lastname: Goodman
authors.forename: S
authors.initials: S
authors.lastname: Matzku
authors.forename: A
authors.initials: A
authors.lastname: Jonczyk
authors.forename: K R
authors.initials: KR
authors.lastname: Lamborn
authors.forename: G L
authors.initials: GL
authors.lastname: DeNardo
mesh_terms: D000230:Adenocarcinoma / Q000098:blood supply* / Q000532:radiotherapy*; D020533:Angiogenesis Inhibitors / Q000627:therapeutic use*; D000818:Animals; D001943:Breast Neoplasms / Q000098:blood supply* / Q000532:radiotherapy*; D003131:Combined Modality Therapy; D005260:Female; D006571:Heterocyclic Compounds / Q000138:chemical synthesis / Q000493:pharmacokinetics / Q000627:therapeutic use*; D006801:Humans; D007205:Indium Radioisotopes / Q000493:pharmacokinetics / Q000627:therapeutic use; D008657:Metabolic Clearance Rate; D051379:Mice; D008819:Mice, Nude; D009389:Neovascularization, Pathologic / Q000517:prevention & control*; D009842:Oligopeptides / Q000138:chemical synthesis / Q000493:pharmacokinetics / Q000627:therapeutic use*; D010456:Peptides, Cyclic / Q000627:therapeutic use*; D016499:Radioimmunotherapy; D019275:Radiopharmaceuticals / Q000138:chemical synthesis / Q000493:pharmacokinetics / Q000627:therapeutic use*; D014407:Tumor Cells, Cultured
chemical_list: D020533:Angiogenesis Inhibitors; D006571:Heterocyclic Compounds; D007205:Indium Radioisotopes; D009842:Oligopeptides; D010456:Peptides, Cyclic; D019275:Radiopharmaceuticals; C407039:cyclo(arginyl--glycyl-aspartyl-phenylalanyl-1-aminocyclohexanecarboxylic acid); C407040:indium-111-DOTA-peptide chimeric L6; C047981:arginyl-glycyl-aspartic acid