2:25 PM
 | 
Dec 05, 2018
 |  BC Extra  |  Tools & Techniques

Cell-free DNA assay can detect cancer in 10 minutes

University of Queensland researchers have developed a 10-minute, cell-free DNA (cfDNA) diagnostic assay that can detect multiple cancers by exploiting epigenetically programmed methylation patterns in cancer DNA that increases binding to gold nanoparticles.

In a paper published in Nature Communications, the scientists said that genomic DNA from normal cells and cancer cells have different methylation patterns. Normal cell DNA has methylcytosines dispersed throughout the genome, whereas cancer cell DNA is hypomethylated and contains methylcytosine clusters. The methylation clusters appeared to change DNA conformation in aqueous solution and increase binding to gold surfaces.

To detect cancer based on the methylation landscape differences, the team developed a method to measure the higher adsorption of cancer DNA to gold nanoparticles compared with normal DNA.

Using DNA extracted from tissue samples from healthy individuals and breast, prostate and lymphoma cancer patients, electrochemical measurement of DNA-gold affinity showed high specificity and sensitivity for cancer detection (area under the ROC curve = 0.909).

The technique could be used to detect cancer in 10 minutes using plasma-derived cfDNA samples from healthy individuals and breast and colorectal cancer patients (AUC = 0.887). By adding salt to the assay, the affinity of the plasma-derived cfDNA to the gold nanoparticles could be visually observed via color change with an AUC of 0.785.

The authors said the technique can only detect the presence of the disease, and not the cancer type, stage or disease recurrence.

In June, Grail Inc. (Menlo Park, Calif.) reported data from its Circulating Cell-Free Genome Atlas (CCGA) study which used three prototype sequencing assays to detect plasma cfDNA mutations and other genomic changes. Grail showed its method could detect early and late-stage cancer as well as differentiate between types of cancer, including 90% of ovarian cancer and 80% of pancreatic cancer at 95% specificity (see "Grail Reports First Data from CCGA Study").

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