Modified polio vaccine helps fight deadly brain tumors
A modified version of the polio vaccine, infused straight into aggressive brain tumours, helped some patients live for years longer than they normally would have, doctors reported yesterday.
It's no miracle cure - only about 20 per cent of patients with gliomas were helped - but some are alive six years later, the team reported.
It's a hopeful enough finding to move forward and test the vaccine in more people, the team at the Duke University School of Medicine said.
"It's very unusual, almost unprecedented to get this kind of long-term survival," neurologist Dr Darell Bigner, who led the study team, said.
The Duke team tested 61 glioma patients over five years. They all had grade IV gliomas, a group of brain tumours that includes glioblastoma.
These patients have a "dismal" diagnosis, the Duke team wrote in the New England Journal of Medicine. "There is currently no effective therapy."
Standard treatment of brain tumours includes surgery if the tumour is somewhere reachable; chemotherapy; and radiation. But if the tumour is aggressive, it's usually fatal.
"These are people who failed everything," Bigner said. "Virtually all patients, no matter what you treat them with, are dead within in two years."
Average Survival Rate
About a third of all brain tumours are gliomas, according to the National Brain Tumor Society. About 80,000 people a year are diagnosed with a brain tumour, and about 24,000 of those are malignant. "The average survival rate for all malignant brain tumour patients is only 34.7 per cent," the group says.
But there's evidence that some viruses can home in on tumours and kill them. It's not clear why, but viruses can also make tumours more visible to the immune system.
The team at Duke worked with the National Cancer Institute to design and manufacture a modified version of polio vaccine virus.
Polio viruses are attracted to nerve cells - that's why they cause paralysis.
The medical team used polio viruses already weakened and altered for use in polio vaccines, and genetically engineered them to carry parts of a common cold virus, called a rhinovirus, known to be attracted to glioma cells.
"We inject the virus directly into brain tumours and it kills all the tumour cells it comes in contact with," Bigner said. "The most important thing is, it sets up a secondary immune response and really destroys the distant tumour cells."