Circulating tumor DNA and tumor-derived exosomes are becoming popular as non-invasive cancer diagnostic tools, termed “liquid” biopsy. Standard next-generation sequencing (NGS) DNA processing approaches enable broad identification of both known and unknown tumor-associated variants, including single nucleotide variants. However, even with the highest fidelity sequencing platforms, errors introduced at >0.1% limit identification of disease associated variants that occur at <1% frequency. This increases the risk of over-representation of false variants and diminishes the clinical relevance of such tests.
University of Utah researchers have developed a droplet digital PCR (ddPCR) approach for enhancing detection sensitivity. This ddPCR approach has the following proprietary intervening steps to enrich circulating tumor DNA: (1) high-throughput automated gel extraction to isolate subfractions of the mononucleosomal peak, and (2) specific adapter sequences or molecular identifiers that allow grouping of PCR duplicates into “family sizes.”