Blood Test Could Diagnose Brain Cancer, Track Progression and Guide Treatment

Glioblastoma (GBM) is a particularly aggressive type of brain cancer with a five-year survival rate of only 5%. Researchers have now identified a biomarker that could be used in blood tests to diagnose GBM, track its progression and guide treatment. This means non-invasive liquid biopsy for GBM could be a great help for patients, allowing them to receive the care they need more quickly. Such a liquid biopsy test could potentially have enormous value in treating GBM.

Researchers at Penn State College of Medicine (Hershey, PA, USA) studied an antigen receptor, called interleukin-13 receptor α2 (IL13Rα2), which increases in the tumor tissue of over 75% of GBM patients. The team examined the utility of IL13Rα2 as a biomarker for GBM by analyzing the tumor tissue and blood plasma of 79 patients with primary GBM, along with the blood plasma of 23 control patients, from two separate health systems. The control patients had been primarily diagnosed with either spinal stenosis or arteriovenous malformation but did not suffer from any malignancy or chronic inflammation.

In the patients’ plasma, the team specifically examined extracellular vesicles, which are small particles released by cells and carry material from those cells. The researchers found that GBM patients had significantly high IL13Rα2 levels in their blood plasma as compared to control patients and that the IL13Rα2 was mostly concentrated on extracellular vesicles derived from tumor cells. It was also found that these IL13Rα2 levels in blood plasma were correlated with the IL13Rα2 levels in the patients’ tumors.

The finding is significant as IL13Rα2 has been demonstrated to have a patchy distribution in GBM tumors, raising doubts over whether a needle biopsy or small sample of tumor tissue is representative of the tumor as a whole. In addition, the researchers found that elevated levels of IL13Rα2 in both plasma and tumors were a predictor of longer overall survival. In fact, patients with high levels of plasma IL13Rα2 had a 6.5 month longer median overall survival as compared to patients with low levels.

“Patients normally receive imaging, such as MRI or CT scans, to diagnose and track the progression of brain tumors, but it can be difficult for physicians to tell from those scans if the patient is getting better or worse because they don’t provide detail at the cellular or molecular level,” said Vladimir Khristov, graduate and medical student, Penn State. “That is why we need a supplemental diagnostic test to help physicians determine if the tumors are responding to therapy and regressing, or if they are getting worse and need additional treatment.”

“A liquid biopsy may facilitate diagnosis and more importantly provide a better understanding of the tumor’s response to treatment in a way that is lacking with our current technologies,” added Brad Zacharia, associate professor of neurosurgery and of otolaryngology, Penn State.

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