18th February 2020
Only 15% of people with a cancerous brain tumour will survive for 5 years or more after diagnosis.
Medulloblastoma is a type of brain tumour that accounts for 15-20% of all childhood brain tumours – and there are currently no targeted treatments available for patients.
Surgery can be challenging, or even impossible to perform, while drugs struggle to get into the brain because of a natural protective barrier, called the blood-brain barrier, that exists around it.
Unfortunately, that means that people with brain tumours such as medulloblastoma have limited options – which means that around 35% of children will sadly pass away within 5 years of diagnosis.
The blood-brain barrier exists primarily to protect the brain from bacteria and viruses that may be circulating in the blood. It is a selective barrier, which means that important cells and molecules that are crucial for the brain to function can pass through, while harmful things are kept outside.
But unfortunately, this protective barrier also creates a problem for the treatment of brain cancer, as many cancer drugs can’t cross the barrier into the brain. This contributes to the low survival rates for medulloblastoma and other types of brain cancer – currently only 15 out of every 100 people with a cancerous brain tumour will survive for 5 years or more after being diagnosed.
The more we uncover about the biology of these tumours, the more we learn what makes them different to healthy brain tissue. It's this knowledge that will lead to the development of new targeted therapies.
Researchers in Toronto, part-funded by Worldwide Cancer Research, have recently discovered a flaw in the genetic code of medulloblastoma.
Our genetic code, wrapped up in our DNA, is a long string of code made up of 4 letters. Written out, your genetic code would fill 5,000 books. And those books would contain the essential recipes that make all the working parts of your body. Amazingly, all these recipes only make up around 2% of the code – approximately 100 of those 5,000 books. The remaining 98% is a mystery.
Our researchers found an alteration to the genetic code in the ‘mystery 98%’ portion in DNA from brain tumours. And this discovery opens up a whole new approach for treating these tumours
The alteration was shown to be involved in the progression of several types of cancer. The researchers also found that it disrupts specific biological processes within cells.
In fact, drugs are already in development that target some of these processes. And some drugs are already used to treat people with other conditions.
This means it may be possible to re-purpose existing drugs for cancers with this genetic alteration. This would bypass early drug development stages, meaning drugs could be used to treat patients sooner.
Dr Michael Taylor, Paediatric Neurosurgeon and researcher at The Hospital for Sick Children in Toronto, said in a statement:
“Our unexpected discovery uncovered an entirely new way to target these cancers that are tremendously difficult to treat and have high mortality rates.
“We've found that with one 'typo' in the DNA code, the resultant cancers have hundreds of mutant proteins that we might be able to target using currently available immunotherapies.”