Breaking the blood-brain barrier

Scientists from the University of Oxford have broken the blood-brain barrier, allowing cancer drugs to be delivered to life-threatening cancers which have spread to the vital organ.

The study – in mice and tissue cultures – used a protein called TNF, which is able to seek out sites in the brain where the cancer has spread by recognising a marker found only on tumour blood vessels. TNF homes in on these sites and temporarily opens the blood-brain barrier (BBB) allowing drugs to pass from the blood system into the tumour.

The BBB is a protective shield that prevents potentially dangerous particles entering the brain, but also stops cancer drug reaching their target.

“Treatments that work very well against the original site of the cancer lose their effectiveness when the cancer spreads to the brain as these drugs are prevented from getting to the tumour because of the blood-brain barrier,” said Dr Nicola Gibson, from the Department of Oncology.

“A number of attempts have been made to open up the BBB but they’re all struggled because they’re either not specific enough to open up the BBB only at the site of the tumour or not effective enough to allow the drug across to kill the cancer.”

Researchers showed the TNF only broke down the BBB in blood vessels that pass through the tumour, leaving healthy parts of the brain undamaged by potentially toxic drugs.

The research – published in the Journal of the National Cancer Institute – showed that when TNF is injected into the blood stream, breast cancer drug Herceptin was able to reach cancer cells in the brain, which it would not normally have been able to.

“Getting treatments through the blood-brain barrier remains one of the greatest challenges for cancer researchers,” said Dr Kat Arney, science information manager at Cancer Research UK, who funded the work.

“This exciting result points the way to a potentially game-changing moment in finding ways to treat cancers that have spread to the brain. We now need to test this approach in cancer patients to see if it will have the same effect.”

Journal of the National Cancer Institute http://jnci.oxfordjournals.org/