Low Cost, Highly Sensitive Blood Test for Cancer Makes Regular Monitoring Affordable

Current methods of testing for cancers can suffer from a lack of sensitivity or from being too expensive to be used for regular screening. The DNA in our blood, the genetic information that tells our cells how to synthesize proteins and other important biological building blocks, is produced by different organs in our body. Cancer cells also release DNA into the bloodstream that can be detected by analyzing blood samples, known as liquid biopsies. However, sifting through all the genetic material in a sample – a method called whole-genome sequencing – can be expensive and labor intensive. Some clinicians instead target cancer-specific signatures in cell-free DNA, almost like hunting for specific faces in a large crowd of people instead of inspecting every single individual. Yet, even such methods can be imperfect. Scientists have now discovered a novel low-cost method of testing for cancers. Called the Heatrich-BS assay, the new test sequences clinical samples that have been heated in order to isolate cancer-specific signatures found in a patient’s blood.

Scientists from the National University of Singapore (NUS, Singapore) discovered a way to discard the non-informative sections in a patient’s DNA to target where most cancer-specific biomarkers are concentrated. Our DNA is made up of molecules known as nucleotides: adenine (A), thymine (T), guanine (G) and cytosine (C). Cancer-specific signatures tend to be concentrated in areas of the genome that have high repetitions of C and G nucleotides, known as CpG islands, that make up only around 1% of our genome. The team accidentally discovered that heat destroyed non-informative sections of the genome, but left CpG island largely intact. This allowed them to sequence the remaining genome and detect the presence of cancers for a minute fraction of the average market price. It costs around S$50 from start to finish, compared to other sequencing methods that can cost up to S$1,000 to conduct.

The Heatrich-BS assay has been trialed at the National Cancer Centre in Singapore, monitoring patients with colorectal cancer. By comparing the results of their blood analysis with CT scans that imaged the size of patients’ tumours, the team found that there was a high correlation between how much cancer-specific DNA was detected in a patient’s blood sample and the size of their tumours over time. The new method also provides a promising non-invasive alternative to tissue biopsies. The method has the potential to work universally across all types of cancer since they all demonstrate the property of enriching CpG islands with cancer-specific biomarkers. The assay may also help accelerate future academic research, helping scientists study different subtypes of cancer for a low cost and therefore improving the development of future cancer diagnoses and therapies. The research team is now exploring ways to commercialize the assay by partnering with pharmaceutical and biotechnology companies that can help bring the Heatrich-BS assay to market.

“When you have a S$50 test, it opens up a lot of avenues because it is affordable, so you can do the test quite regularly,” said Assistant Professor Cheow Lih Feng, pointing to the potential for their assay to be used in regular cancer monitoring. “We are getting a much more sensitive assay at almost the same costs as compared to simple protein biomarker tests. Our method really concentrates on sequencing these regions that matter the most.”

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