Multiplex Enrichment and Detection of Rare KRAS Mutations in Liquid Biopsy Samples using Digital Droplet Pre-Amplification.

Abstract

Oncology research is increasingly incorporating molecular detection of circulating tumor DNA (ctDNA) as a tool for cancer surveillance and early detection. However, noninvasive monitoring of conditions with low tumor burden remains challenging, as the diagnostic sensitivity of most ctDNA assays is inversely correlated with total DNA concentration and ctDNA abundance. Here we present the Multiplex Enrichment using Droplet Pre-Amplification (MED-Amp) method, which combines single-molecule emulsification and short-round polymerase chain reaction (PCR) preamplification with digital droplet PCR detection of mutant DNA template. The MED-Amp assay increased mutant signal by over 50-fold with minimal distortion in allelic frequency. We demonstrate detection of as few as three mutant copies in wild-type DNA concentrations ranging from 5 to 50 ng. The MED-Amp assay successfully detected KRAS mutant ctDNA in 86% plasma samples obtained from patients with metastatic pancreatic ductal adenocarcinoma. This assay for high-sensitivity rare variant detection is appropriate for liquid biopsy samples or other limited clinical biospecimens.

• Authors: Erica D Pratt, Robert W Cowan, Sara L Manning, Edmund Qiao, Heather Cameron, Kara Schradle, Diane M Simeone, David B Zhen
• Journal: Analytical chemistry (Anal Chem) Vol. 91 Issue 12 Pg. 7516-7523 (06 18 2019) ISSN: 1520-6882 [Electronic] United States
• PMID: 31072097 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Circulating Tumor DNA
• Fluorescent Dyes
• Proto-Oncogene Proteins p21(ras)

Topics

• Aged
• Aged, 80 and over
• Case-Control Studies
• Circulating Tumor DNA (blood)
• Female
• Fluorescent Dyes (chemistry)
• Gene Frequency
• Humans
• Limit of Detection
• Lipid Droplets (chemistry)
• Liquid Biopsy
• Male
• Middle Aged
• Mutation
• Pancreatic Neoplasms (genetics, pathology)
• Polymerase Chain Reaction
• Proto-Oncogene Proteins p21(ras) (genetics)