title: A triple-targeted ultrasound contrast agent provides improved localization to tumor vasculature.
abstract: OBJECTIVE
  Actively targeting ultrasound contrast agents to tumor vasculature improves contrast-enhanced sonography of tumor angiogenesis. This report summarizes an evaluation of multitargeted microbubbles, comparing single-, dual-, and triple-targeted motifs.
  
  
  METHODS
  Microbubbles were avidin-biotin linked to antibodies against mouse α(V)β(3)-integrin, P-selectin, and vascular endothelial growth factor receptor 2. These receptors are constitutively overexpressed in tumor vasculature. Binding comparisons between targeted microbubble groups were evaluated on mouse SVR angiosarcoma endothelial cells. Levels of the targeted receptors were characterized with flow cytometry. Targeted microbubble groups were administered to human MDA-MB-231 breast cancer tumor-bearing mice (n = 3) followed by contrast-enhanced sonography in a microbubble-sensitive harmonic imaging mode implemented on an ultrasound scanner equipped with a linear array transducer (5 MHz transmit and 10 MHz receive) to evaluate differences in microbubble accumulation in the tumor vasculature.
  
  
  RESULTS
  In vitro analysis showed a 50% increase (P < .001) in triple-targeted microbubble binding over dual-targeted microbubble groups in mouse SVR cells. Mice bearing MDA-MB-231 tumors showed a 40% increase in tumor image intensity after dosing with triple-targeted microbubbles compared with single- and dual-targeted microbubbles (P = .006). Histologic staining confirmed the presence of α(V)β(3)-integrin, P-selectin, and vascular endothelial growth factor receptor 2 in the tumors.
  
  
  CONCLUSIONS
  Microbubble accumulation in the tumor vasculature was improved using a triple-targeted microbubble approach.
authors.affiliation: University of Alabama at Birmingham, G082 Volker Hall, 1670 University Blvd, Birmingham, AL 35294 USA.
authors.forename: Jason M
authors.initials: JM
authors.lastname: Warram
authors.forename: Anna G
authors.initials: AG
authors.lastname: Sorace
authors.forename: Reshu
authors.initials: R
authors.lastname: Saini
authors.forename: Heidi R
authors.initials: HR
authors.lastname: Umphrey
authors.forename: Kurt R
authors.initials: KR
authors.lastname: Zinn
authors.forename: Kenneth
authors.initials: K
authors.lastname: Hoyt
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D045744:Cell Line, Tumor; D003287:Contrast Media / Q000378:metabolism*; D005434:Flow Cytometry; D006394:Hemangiosarcoma / Q000000981:diagnostic imaging*; D007124:Immunoenzyme Techniques; D039302:Integrin alphaVbeta3 / Q000378:metabolism*; D008325:Mammary Neoplasms, Experimental / Q000000981:diagnostic imaging*; D051379:Mice; D008819:Mice, Nude; D045423:Microbubbles; D009389:Neovascularization, Pathologic / Q000000981:diagnostic imaging*; D019007:P-Selectin / Q000378:metabolism*; D014463:Ultrasonography; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*
chemical_list: D003287:Contrast Media; D039302:Integrin alphaVbeta3; D019007:P-Selectin; D040301:Vascular Endothelial Growth Factor Receptor-2