Treatment for some aggressive brain cancer patients could be “revolutionised” after scientists found a new way to find out who may benefit from immunotherapy cancer drugs.
Some glioblastoma tumours may respond well to immunotherapy, but there is currently no way to assess this without an invasive brain biopsy – which carries the risk of infection and bleeding.
As a result, biopsies are rarely carried out for glioblastomas prior to surgery to remove the tumour, meaning these patients are missing out on improved treatments.
Now there is hope after researchers developed a new imaging technique which can help spot which patients will benefit from immunotherapy drugs, without the need of a risky biopsy.
The ability to identify those who would benefit from immunotherapy without the need for risky biopsies is a great step forward
Experts hope that the new imaging technique could soon guide personalised treatment for glioblastoma patients, and others have called the finding a “real step forward” for patients.
Glioblastomas are a fast-growing type of brain tumour.
The average survival after a glioblastoma diagnosis is 12 to 18 months.
Only 25% of patients survive more than one year, and only 5% of patients survive more than five years, according to figures from The Brain Tumour Charity.
The main treatments for glioblastomas are surgery, radiotherapy and chemotherapy.
But now, immunotherapy could be used widely thanks to the development of the new “immuno-PET imaging technique” by scientists from The Institute of Cancer Research, London (ICR).
Higher levels of a protein called PD-L1 have been found in rapidly progressing glioblastoma tumours.
The ICR said this protein acts as “the brakes” on the body’s immune system, so blocking the function of this protein could “kick-start” the immune system into fighting the cancer.
Until now, a biopsy has been the only way of assessing the levels of PD-L1 in the brain tumour.
Now scientists have developed a “radiotracer” which binds to PD-L1, enabling medics to measure its levels in glioblastoma patients, the authors wrote in the journal Neuro-Oncology.
The tracer was tested on a small number of patients in Poland.
Eight newly diagnosed glioblastoma patients were given the tracer, followed by scans after 48 and 72 hours.
The scans showed that the tracer successfully binds to PD-L1 positive cells within the tumour and throughout the body.
Five of the patients also received pembrolizumab – a treatment which blocks the function of PD-L1 – before surgery.
The researchers found that these patients had lower levels of the tracer in their tumours – suggesting that the drug is acting on the PD-L1 protein and removing the “brakes” for the immune system so it can fight the cancer.
Three of the five patients have seen their cancer stabilise and not grow any further, the ICR said.
The ongoing clinical trial aims to recruit 36 patients diagnosed with glioblastoma to see whether pembrolizumab given before surgery is effective.
Researchers will also assess whether PET imaging using the radiotracer can be used to monitor progress and adjust treatment as needed.
“This study could revolutionise glioblastoma treatment, as we’ve shown that it is possible to image an immunotherapy target with our radiotracer,” said Dr Gabriela Kramer-Marek, associate professor and group leader in preclinical molecular imaging at The ICR.
“Being able to take a scan of the patient’s body and see the levels of this target means that we can predict the patients’ response, see their immune system responding to the treatment, and alter treatment where necessary – providing a personalised treatment plan based on the unique characteristics of their tumour, all without the need for a pre-surgery biopsy.”
Professor Kristian Helin, chief executive of The ICR, added: “Glioblastoma is a devastating disease, and treatments haven’t significantly changed for decades.
“Although immunotherapies seem like they might be effective, progress has been stalled by not having a biomarker test to show who might benefit from them, or a way to monitor each patient’s response to treatment.
We are pleased to see progress in this area and look forward to following this work as it advances to larger clinical trials
“It’s fantastic to see the advances in technology that mean that innovative imaging techniques could soon guide personalised treatment.”
Commenting, Dr Karen Noble, director of research, policy and innovation at Brain Tumour Research, said: “We are excited about the potential of this new imaging technique to transform the treatment landscape for glioblastoma patients.
“The ability to identify those who would benefit from immunotherapy without the need for risky biopsies is a great step forward.
“Personalised treatment plans improve the chances of a treatment being effective. Therefore, we welcome these promising results and look forward to seeing how this technique can improve the lives of patients with aggressive brain tumours.”
Dr Simon Newman, chief scientific officer at The Brain Tumour Charity, said: “These tumours are notoriously difficult to treat, and research into immunotherapy has had mixed results due to the tumour’s ability to hide from the immune system.
“However, we are encouraged by the findings from this study as there is an urgent need for new approaches to monitor and treat this devastating disease.
“Immunotherapies have shown progress in other cancer types, and we hope to see similar advancements for brain tumours.
“We are pleased to see progress in this area and look forward to following this work as it advances to larger clinical trials.”
