Abstract
Accumulation of somatic mutations in genomic DNA is nearly exclusive to cancer cells. During proliferation, a fraction of cancer cells die and release genomic DNA fragments. These released genomic DNA fragments, termed circulating tumor DNA (ctDNA), can be found in blood. ctDNA has potential uses in cancer diagnostics, particularly since the emergence of “massively parallel” next generation sequencing (NGS). However, the detection limit of NGSs was recently shown to be far higher than the actual concentration of ctDNA. To quantify ctDNA as a tumor marker, digital PCR (dPCR) is required to detect very low (i.e., <1%) concentrations of somatic mutations. We have designed a dPCR primer/probe library specific for cancer mutations that were selected from public databases containing 12.5 million entries. Our newly developed system using this library, the Off-The-Shelf (OTS)-Assay, can measure as little as 0.01% of ctDNA, which allows highly sensitive post-treatment cancer surveillance for cancer patients. The high sensitivity of the OTS-Assay may change approaches for measurement of residual cancer during and after treatment.
