The leader in this field is the Galleri test (from GRAIL) which is already in clinical use in some health care networks across the United States. That test uses next-generation sequencing to analyze the arrangement of methyl groups on circulating tumor (or cell-free) DNA (cfDNA) in a blood sample.
The new test, under development by Swedish biotechnology company Elypta AB, has a different premise. It can detect 14 cancer types based on the analysis of glycosaminoglycans, which are a diverse group of polysaccharides that are altered by the presence of tumors. Using plasma and urine samples, the method had a 41.6%-62.3% sensitivity for detecting stage I cancer at 95% specificity.
In comparison, say the authors, other assays have reported 39%-73% sensitivity to stage I cancers, but these estimates are usually limited to 12 cancer types that are considered “high-signal,” and the assays perform poorly in cancers that emit little cfDNA, such as genitourinary and brain malignancies.
“The main advantage of glycosaminoglycans appears to be that they change in the blood and urine at the earliest stages of cancer,” said study author Francesco Gatto, PhD, founder and chief scientific officer at Elypta. “Consequently, this method showed an impressive detection rate in stage I compared to other emerging methods.”
The study was published online in Proceedings of the National Academy of Sciences.
Combine tests?
Dr. Gatto commented that he “could envision that one day we may be able to combine these methods.”
“The same blood specimen could be used to test both glycosaminoglycans and genomic biomarkers,” said Dr. Gatto. “This strategy could hopefully detect even more cancers than with either method alone, and the resulting performance may well be sufficient as a one-stop-shop screening program.”
So how does the new test from Elypta compare with the Galleri test?
“Galleri and similar methods mostly focused on information coming from molecules of DNA naturally floating in the blood,” explained Dr. Gatto. “It makes sense to conduct research there because cancers typically start with events in the DNA.”
He noted that the current study explored a new layer of information, molecules called glycosaminoglycans, that participate in the metabolism of cancer.
“This method detected many cancers that the previous methods missed, and a substantial proportion of these were at stage I,” said Dr. Gatto. “Cancer is a complex disease, so the most layers of information we can probe noninvasively, say with a blood test, the more likely we can catch more cancers at its earliest stage.”
Other platforms typically rely on sequencing and detecting cancer-derived fractions of cfDNA, but these methods have challenges that can interfere with their usage. For example, some cancer types do not shed sufficient cfDNA and it cannot be accurately measured.
“An advantage on focusing on glycosaminoglycans is that the method does not require next-generation sequencing or similarly complex assays because glycosaminoglycans are informative with less than 10 simultaneous measurements as opposed to Galleri that looks at over 1 million DNA methylation sites,” he said.
“This makes the assay behind the test much cheaper and robust – we estimated a 5-10 times lower cost difference,” Dr. Gatto said.