Blood-based biomarkers for brain tumours identified

New Delhi: A study by researchers at the Indian Institute of Science (IISc), along with collaborators, has identified potential blood-based biomarkers to predict disease progression and survival times in those with late-stage brain tumours.

The team included researchers from the Centre for BioSystems Science and Engineering (BSSE) at IISc, the Mazumdar Shaw Centre for Translational Research and Mazumdar Shaw Medical Foundation.

They analysed tumour and blood samples from individuals with gliomas – tumours that occur in the brain – to identify surface proteins on immune cells in the blood whose levels were closely linked to tumour progression.

“Our pilot study suggests that we can potentially use two blood-based biomarkers present on immune cells to identify patients who might not perform well with particular treatment strategies,” says Siddharth Jhunjhunwala, Assistant Professor in BSSE, and senior author of the study.

Conventional cancer treatments like chemotherapy are often ineffective in treating these tumours. This has prompted a shift to newer techniques like immunotherapy, which involves provoking the immune system of the patient to attack the tumour cells. However, attempts to use some of the standard immunotherapies to treat gliomas have met with limited success. The scientists were trying to address this gap by understanding the immune profile in the tumour microenvironment.

The team collected blood and tumour samples from patients with grade three and grade four gliomas and compared the numbers of specific immune cells called monocytes and neutrophils in these samples.

The team also looked for differences in the composition of surface proteins on these cells across the two grades of tumours. They found that a certain type of monocytes — the M2 monocytes — were present in larger numbers in the samples from grade four tumours. Previous studies have shown that high numbers of M2 monocytes are associated with a suppression of immune responses, and the new finding could help develop new treatment strategies. “Future studies could focus on developing therapies that reduce the numbers of M2 monocytes in the tumour microenvironment or alter their functionality,” says Jhunjhunwala.

The researchers also found that levels of two surface proteins on neutrophils and monocytes, CD86 and CD63, were closely related in both the blood and tumour samples. The presence of high levels of these proteins on immune cells in other tumours has previously been associated with poor prognosis or low chances of survival. “What our study showed is that you do not need to look at these markers only in the tumours, you might be able to look at these just from the blood, and the clinician can make an assessment,” he says.

Jhunjhunwala said that further testing and validation is, however, needed on a larger scale before this can be taken from the lab to the clinic. “We would like to expand our cohort and test for only these two markers now, in individuals with stage three and stage four brain tumours and follow their survival times.”

A report on the study has been published in OncoImmunology.