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Keywords: Mutation detection; Cell-free DNA; Cancer; Clinical testing; Methodology

C. Boysen 1; Q. Liu 3; S. Sommer 1,2

1) SomicsMed, Azusa, CA; 2) MedGomics, Azusa, CA; 3) Genetic Tools, Upland, CA

PCR and NGS based technologies are being developed for mutation detection in cfDNA or ctDNA from liquid biopsies. However, they are often not sensitive or specific enough for early detection of cancer and other applications, where a minimum amount of template with specific nucleotide variants, such as single base substitutions, insertions, and deletions, are present in great excess of wildtype genome.
The Pyrophosphorolysis-activated polymerization (PAP) methodology is a more affordable, next-generation nucleic acid amplification technology beyond PCR that possesses ultrahigh sensitivity and selectivity in detection of such mutations without false positives in non-invasive liquid biopsies from patients. The high specificity of PAP derives from the serial coupling of activation of a 3' blocked pyrophosphorolysis-activable oligonucleotide with extension of the unblocked, activated oligonucleotide.
Here we demonstrate the detection of specific cancer mutations in KRAS, EGFR, and BRAF at very low frequencies and down to just one molecule of mutated DNA without detection of false positives.