title: Quantification of vascular endothelial growth factor, interleukin-8, and basic fibroblast growth factor in plasma of cancer patients and healthy volunteers - comparison of ELISA and microsphere-based multiplexed immunoassay.
abstract: BACKGROUND
  Vascular endothelial growth factor (VEGF), interleukin-8 (IL-8) and basic fibroblast growth factor (basic FGF) are angiogenic growth factors which may be useful as biomarkers in drug development, where they could give early information on the antiangiogenic activity of novel anticancer compounds.
  
  
  METHODS
  We compared two commercially available assays, enzyme linked immunosorbent assay (ELISA) and a multiplexed bead-based immunoassay (xMAP), for the quantification of these factors in plasma samples from more than 100 cancer patients and healthy individuals.
  
  
  RESULTS
  For VEGF and IL-8, but not for basic FGF, xMAP was more sensitive than the respective ELISA. This was true for healthy subjects as well as for cancer patients. Intraassay precision was comparable between both assay formats. Linear regression analysis of VEGF concentrations demonstrated a good correlation between ELISA and xMAP. Bland-Altman analysis showed a systematic difference between both assays, with ELISA giving higher concentration values. VEGF levels were higher in female volunteers, and both assays were able to detect this difference.
  
  
  CONCLUSIONS
  Multiplexed microsphere-based immunoassays have the potential to substitute ELISA for the detection of proangiogenic growth factors in clinical studies. Their shorter assay times and their ability to quantify multiple analytes in a small sample volume are advantageous.
authors.affiliation: Bayer HealthCare, Wuppertal, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Kornacker
authors.forename: Angelika
authors.initials: A
authors.lastname: Roth
authors.forename: Olaf
authors.initials: O
authors.lastname: Christensen
authors.forename: Jörn
authors.initials: J
authors.lastname: Krätzschmar
authors.forename: Georg
authors.initials: G
authors.lastname: Wensing
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D016222:Fibroblast Growth Factor 2 / Q000097:blood*; D006262:Health; D006801:Humans; D007118:Immunoassay; D016209:Interleukin-8 / Q000097:blood*; D016014:Linear Models; D008297:Male; D008863:Microspheres; D008875:Middle Aged; D009369:Neoplasms / Q000097:blood*; D012015:Reference Standards; D012680:Sensitivity and Specificity; D012727:Sex Characteristics; D042461:Vascular Endothelial Growth Factor A / Q000097:blood*
chemical_list: D016209:Interleukin-8; D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2