A blood test that measures the amount of cfDNA in the blood – also known as a liquid biopsy – has been correlated with how patients will progress following a glioblastoma diagnosis.
Within the study, which has been published in Clinical Cancer Research, researchers from the Abramson Cancer Center of the University of Pennsylvania (PA, USA) have demonstrated that individuals with a higher concentration of cfDNA have shorter progression-free survival than patients with less cfDNA.
Additionally, the team also noted that cfDNA spikes in patients either at the time of, or just before, their disease progresses. They also revealed that when comparing genetic sequencing of solid tissue biopsies with liquid biopsies, it was observed that while both biopsies could detect genetic mutations in more than half of patients, none of those mutations overlapped. This finding suggests that liquid biopsy may provide complementary information regarding the molecular or genetic makeup of each tumor.
“Doctors have begun using liquid biopsies more frequently to monitor certain cancers – particularly lung cancer – in recent years as research has shown their effectiveness in other disease sites. But until now, there has been little focus on the clinical utility of liquid biopsy in brain tumors,” commented senior author of the study, Erica Carpenter (Liquid Biopsy Laboratory, University of Pennsylvania).
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The current study included 42 participants who were diagnosed with newly diagnosed glioblastoma. Each individual had blood tests taken at the time of diagnosis, before surgery and at regular intervals throughout their standard of care chemotherapy and radiation. In 28 participants, a lower concentration of cfDNA was observed pre-surgery and these individuals had almost double the progression-free survival (median 4.9 months).
A sub-analysis of 20 participants revealed that liquid biopsy detected at least one mutation in 11 patients and all of those mutations were different than what was detected in their solid tumor biopsy analysis. According to the investigators, the detection of additional mutations is particularly exciting as an effective therapy for glioblastoma will ultimately require combination therapies due to the heterogeneity of the tumor.
“If liquid biopsy can give us a more comprehensive view of the molecular profile of the tumor, we can potentially pick more effective combinations for each patient,” concluded lead author, Stephen Bagley (Perelman School of Medicine, University of Pennsylvania).
The team have noted that their work is more hypothesis-generating than practice-changing but are hoping to continue with enrolment of patients. The researchers also plan to perform a larger data analysis of their results and hope to carry out tumor DNA sequencing on multiple different samples of the resected tumors from each patient, in order to discover the full molecular profile of each.