In a new study, researchers found that genetic mutations that promote the growth of the most common type of brain tumors can be accurately detected and monitored in blood samples using an enhanced form of liquid biopsy.
Comparing blood samples from patients with gliomas with tumor biopsy tissues from the same patients, the researchers found that a novel digital droplet polymerase chain reaction (ddPCR) blood test they pioneered could accurately detect and monitor overtime two mutations of the gene TERT.
The mutations, labeled C228T and C250T, are known to promote cancer growth and are present in more than 60% of all gliomas, and in 80% of all high-grade gliomas, the most aggressive and life-threatening type.
This finding has the potential to strongly improve the diagnosis and monitoring of gliomas.
The research was conducted by a team at Massachusetts General Hospital (MGH).
Gliomas are tumors of glia, central and peripheral nervous system cells that support and protect neurons, the cells that transmit electrical impulses.
Liquid biopsy is a method for detecting cancer by looking for fragments of tumor DNA that circulate in the blood.
The technique has been shown to be sensitive at detecting the presence of some forms of cancer, but brain tumors have until now posed a formidable barrier.
Liquid biopsy is particularly challenging in brain tumors because mutant DNA is shed into the bloodstream at a much lower level than any other types of tumors.
In the study, the team first tested the performance of the ddPCR assay in tumor tissue and found that the results were in perfect agreement with the results from an independently performed clinical laboratory assessment of TERT mutations in the tumor specimens.
They then looked at samples of blood plasma matched to patient tumors and found that the ddPCR assay could detect TERT mutations both in samples from MGH as well as from similarly matched plasma and tumor samples from collaborators at other institutions.
The ddPCR assay has an overall sensitivity (ability to detect the presence of a glioma) of 62.5%, which is a tenfold improvement over any prior assay for TERT mutations in the blood for brain tumors, compared to the standard of tissue-based detection of TERT mutations.
The test is easy to use, quick, and low cost and could be performed in most laboratories. Importantly, the test can also be used to follow the course of the disease.
The team’s goal is to expand this blood test to be able to differentiate many types of brain tumors.
One author of the study is Leonora Balaj, Ph.D.
The study is published in Clinical Cancer Research.
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