A research team led by Assistant Professor Cheow Lih Feng (Department of Biomedical Enigneering, CDE) have discovered a novel low-cost method of testing for cancers, providing a promising non-invasive alternative to tissue biopsies.
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.
The new method costs around S$50 from start to finish, compared to other sequencing tests that can cost up to S$1,000 to conduct. The team comprising researchers from the Department of Biomedical Engineering as well as the NUS Institute for Health Innovation & Technology, is now exploring industry partnerships to bring their technology 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 Asst Prof Cheow, pointing to the potential for their assay to be used in regular cancer monitoring.
Liquid biopsies for cancer
Current methods of testing for cancers can suffer from a lack of sensitivity or from being too expensive to be used for regular screening.
DNA in blood, the genetic information that tells cells how to synthesise proteins and other important biological building blocks, is produced by different organs in the body. Cancer cells also release DNA into the bloodstream that can be detected by analysing 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 labour-intensive.
Some clinicians instead target cancer-specific signatures in cell-free DNA - similar to hunting for specific faces in a large crowd instead of inspecting every individual. Yet, even such methods can be imperfect.
"Some patients may have cancer signatures that look slightly different and allow them to slip through the screening process," Asst Prof Cheow said.
A more sensitive test at a small fraction of the price
The team has discovered a way to discard the non-informative sections in a patient's DNA to target where most cancer-specific biomarkers are concentrated.
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 one per cent of the genome.
"We were performing some unrelated experiments, and one of our researchers heated a sample," Asst Prof Cheow said, recounting the team's accidental discovery that heat destroyed non-informative sections of the genome, but left CpG island largely intact.
This allowed the team to sequence the remaining genome and detect the presence of cancers for a minute fraction of the average market price.
"We are getting a much more sensitive assay at almost the same costs as compared to simple protein biomarker tests," Asst Prof Cheow said. "Our method really concentrates on sequencing these regions that matter the most."
The NUS team recently published their findings in the scientific journal Science Advances, and a patent has also been filed for their discovery.
| Benefitting patients, doctors and scientists
The Heatrich-BS assay has been trialled 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. "This way, doctors can monitor patients for their response to treatment and tailor their therapy regimes," Asst Prof Cheow said. He added that the test is also a "one-size-fits-all" method with 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. Asst Prof Cheow and his team are now exploring ways to commercialise their assay by partnering with pharmaceutical and biotechnology companies that can help bring the Heatrich-BS assay to market. "We are excited about our results and licensing discussions are underway," he said. |
