title: Detection of KRAS Mutations in Circulating Tumor DNA by Digital PCR in Early Stages of Pancreatic Cancer.
abstract: BACKGROUND
  Since surgical removal remains the only cure for pancreatic cancer, early detection is of utmost importance. Circulating biomarkers have potential as diagnostic tool for pancreatic cancer, which typically causes clinical symptoms only in advanced stage. Because of their high prevalence in pancreatic cancer, KRAS proto-oncogene, GTPase [KRAS (previous name: Kirsten rat sarcoma viral oncogene homolog)] mutations may be used to identify tumor-derived circulating plasma DNA. Here we tested the diagnostic sensitivity of chip based digital PCR for the detection of KRAS mutations in circulating tumor DNA (ctDNA) in early stage pancreatic cancer.
  
  
  METHODS
  We analyzed matched plasma (2 mL) and tumor samples from 50 patients with pancreatic cancer. Early stages (I and II) were predominant (41/50) in this cohort. DNA was extracted from tumor and plasma samples and tested for the common codon 12 mutations G12D, G12V, and G12C by chip-based digital PCR.
  
  
  RESULTS
  We identified KRAS mutations in 72% of the tumors. 44% of the tumors were positive for G12D, 20% for G12V, and 10% for G12C. One tumor was positive for G12D and G12V. Analysis of the mutations in matched plasma samples revealed detection rates of 36% for G12D, 50% for G12V, and 0% for G12C. The detection appeared to be correlated with total number of tumor cells in the primary tumor. No KRAS mutations were detected in 20 samples of healthy control plasma.
  
  
  CONCLUSIONS
  Our results support further evaluation of tumor specific mutations as early diagnostic biomarkers using plasma samples as liquid biopsy.
authors: Bayer Pharma AG, Biomarker Research, Berlin, Germany.
authors: Nora
authors: N
authors: Brychta
authors: Bayer Pharma AG, Biomarker Research, Berlin, Germany.
authors: Thomas
authors: T
authors: Krahn
authors: Bayer Pharma AG, Biomarker Research, Berlin, Germany. oliver.vonahsen@bayer.com.
authors: Oliver
authors: O
authors: von Ahsen
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood / Q000235:genetics*; D004273:DNA, Neoplasm / Q000097:blood* / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D009154:Mutation; D010190:Pancreatic Neoplasms / Q000097:blood / Q000175:diagnosis / Q000235:genetics*; D016133:Polymerase Chain Reaction; D000090063:Proto-Oncogene Mas; D016283:Proto-Oncogene Proteins p21(ras) / Q000097:blood / Q000235:genetics*
chemical_list: D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; C117307:KRAS protein, human; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D016283:Proto-Oncogene Proteins p21(ras)