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Guide for Liquid Biopsy in Individual Glioblastoma Patients

Study by the University of Pennsylvania demonstrates the benefits of imaging to identify suitability of liquid biopsy of glioblastoma patients.

About 12,000 Americans are diagnosed with glioblastoma (GBM) each year, it is the most common malignant primary brain tumour in adults. With a five-year survival rate between five and 10 percent, it is also the deadliest. Formation of the tumour is a result of multiple genetic mutations which makes it difficult to track over time especially when collecting a new tissue sample would require repeat brain surgery. For GBM almost all patients experience a recurrence with a vastly different genetic makeup.

An alternative to monitor such cancers would be through liquid biopsy, which can provide crucial information for treatment and clinical care of the patient, unfortunately it is not feasible in all cases of GBM. Research by the Perelman School of Medicine at the University of Pennsylvania and Penn’s Abramson Cancer Centre demonstrates how brain imaging may be able to predict when a blood test would or would not provide clinically actionable information for doctors to more efficiently guide treatment plans for patients.

The study published on the journal Neuro-Oncology Advances found that the key was the ability to image two things – the blood brain barrier and a type of immune cell called macrophages – which correlate with the amount of circulating DNA in the blood stream.

A liquid biopsy allows doctors to measure the among of circulating DNA (cfDNA) and circulating tumour DNA (ctDNA) in the blood which are release by cancer cells. The researchers show that through an MRI a picture of the state of the blood brain barrier will determine the levels of cfDNA and ctDNA likely to be in a patient’s blood. Additionally, they also found a correlation between the amount of cfDNA and the density of macrophages in a GBM. This represents a major stumbling block to the immune system fighting the tumour.

“By better understanding the macrophage makeup in a given patient’s tumour, researchers may be able to identify which patients are the best candidates for treatments targeted against macrophages, or for immunotherapy in general,” said the study’s lead author Seyed Ali Nabavizadeh, MD, an assistant professor of Radiology at Penn.

“The more information we have about a tumour, the better. The combination of being able to measure the integrity of the blood brain barrier, understanding the density of macrophages, and tracking the tumour through liquid biopsy may be able to help us tailor our treatment decisions so that each patient is getting precision therapy that gives them the best chance of seeing a benefit,” said the study’s senior author Stephen Bagley, MD, MSCE, an assistant professor of Haematology-Oncology.

The researchers were not only able to show how imaging may predict the feasibility of liquid biopsy in the GBM patient but also paves the way for what this combination can discover. They mention that further research is needed to understand the use of this information for treatment outcome and disease progression. [APBN]