title: Cancer therapy monitoring in xenografts by quantitative analysis of circulating tumor DNA.
abstract: BACKGROUND
  Circulating tumor DNA (ctDNA) is a promising biomarker in cancer.
  
  
  METHODS
  We generated xenograft models of cancer and detected ctDNA in plasma by qRCR targeting human AluJ sequences.
  
  
  RESULTS
  Our assay reached single cell sensitivity in vitro and a correlation between ctDNA amount and tumor size was observed in vivo. Treatment with a mitogen activated protein kinase kinase (MEK)-inhibitor (BAY 869766) reduced ctDNA levels. Using this assay, we also confirmed that high levels of cell-free DNA are found in cancer patients compared to healthy individuals.
  
  
  CONCLUSIONS
  We show that ctDNA may be useful biomarker for monitoring tumor growth and treatment response.
authors.affiliation: Global Biomarker Research, Bayer Pharma AG, Berlin, Germany.
authors.forename: Tobias M
authors.initials: TM
authors.lastname: Gorges
authors.forename: Johanna
authors.initials: J
authors.lastname: Schiller
authors.forename: Arndt
authors.initials: A
authors.lastname: Schmitz
authors.forename: Daniel
authors.initials: D
authors.lastname: Schuetzmann
authors.forename: Christoph
authors.initials: C
authors.lastname: Schatz
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Zollner
authors.forename: Thomas
authors.initials: T
authors.lastname: Krahn
authors.forename: Oliver
authors.initials: O
authors.lastname: von Ahsen
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage; D014408:Biomarkers, Tumor / Q000097:blood*; D001943:Breast Neoplasms / Q000097:blood* / Q000188:drug therapy / Q000473:pathology; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000097:blood* / Q000188:drug therapy / Q000473:pathology; D004247:DNA / Q000097:blood*; D004159:Diphenylamine / Q000008:administration & dosage / Q000031:analogs & derivatives; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D051379:Mice; D008819:Mice, Nude; D060888:Real-Time Polymerase Chain Reaction / Q000592:standards; D012015:Reference Standards; D013449:Sulfonamides / Q000008:administration & dosage; D047368:Tumor Burden; D023041:Xenograft Model Antitumor Assays / Q000379:methods*
chemical_list: D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; C544830:N-(3,4-difluoro-2-(2-fluoro-4-iodophenylamino)-6-methoxyphenyl)-1-(2,3-dihydroxypropyl)cyclopropane-1-sulfonamide; D013449:Sulfonamides; D004247:DNA; D004159:Diphenylamine