New laser treatment ups efficiency of brain tumour drugs

New York: A team of US researcher has found that a laser system already in place to kill brain tumours can also be used to disrupt temporarily the blood-brain barrier enabling the crucial chemotherapy drugs to pass into the brain for up to six weeks. The blood-brain barrier refers to the defence system in the brain that filters bacteria and chemicals.

This defence system also block most chemotherapy drugs. The findings showed for the first time that the blood-brain barrier can be temporarily disrupted at tumour sites to provide a precise location and take a longer “window of opportunity” for chemotherapy drugs to enter the tumour and take effect.

“This gives us a very significant window of time to give chemotherapy,” said David Tran, chief of neuro-oncology at University of Florida in the US. The study was published in the journal PLOS ONE. Opening the blood-brain barrier also raises the possibility that immunological techniques can be used more effectively against brain tumours.

A leaky barrier allows the tumour to be recognised more readily by the immune system and provides immune cells better access to the tumour. Combining laser ablation technology with a drug known as a PD-1 inhibitor that prevents tumour cells from evading the immune system could greatly enhance immunotherapy, Tran pointed out.

The temporary “window” raises the possibility that a host of chemotherapy drugs once rendered ineffective by the blood-brain barrier could now be used against glioblastoma — most common and deadliest malignant brain tumour in adults. Researchers discovered that the blood-brain barrier opens soon after a procedure known as MRI-guided laser ablation.

The researchers found that the laser beam creates the perfect temperature around the tumour — just warm enough to disrupt the blood-brain barrier but not so hot for neurons to die. In a pilot trial, 14 brain tumour patients underwent laser ablation and were treated with doxorubicin, a chemotherapy drug that is normally blocked by the blood-brain barrier. Preliminary data suggest there could be a survival benefit to giving chemotherapy during the four to six-week opening in the blood-brain barrier, Tran noted.