UCSF doctors use viruses to attack brain tumors


For a man about to undergo brain surgery, John Toner is about as feisty as they come, "My diagnosis? I'm a crazy old man. And I have GBM, glioblastoma multiform."

It's a brain tumor that's returned twice after previous surgeries. UCSF neurosurgeon, Dr. Manish Aghi, says that this time doctors will use investigational technique to help kill the cancerous cells, "We are injecting a virus into the tumor. It is a replicating retrovirus that spreads throughout the tumor but itself causes no harm until we deliver a pro-drug."

The cancer drug that Toner will receive will only be activated when it combines with agents carried into the tumor cells by the virus. But according to Aghi, the challenge is to make sure that viral cocktail reaches the entire tumor. To do that, his team will peer into Toner's brain during the procedure with an MRI, "The MRI allows for visualization to confirm that the virus has been delivered throughout the tumor."

He says the first MRI images are combined with special software and used to place a guidance system called ClearPoint onto the skull. It will ultimately help the surgeons to drill through and reach the tumor while sparing vital brain matter.

"So what they've done is they've made an image of the patient's head with this grid on the surface and they've explored the different ways that they can travel through the brain and they've decided the best place to enter the brain is in this location," said UCSF physicist Dr. Alistaire Martin.

Martin provides updated images as surgeons guide a cannula through the brain and into the tumor. Once it's in place, the team will use a new, experimental technique to slowly force the liquid into the tumor under pressure, known as convection.

With the cannula placed, Aghi's team anxiously watches the images from the MRI. As pressure from the convection system builds, a contrast agent included with the virus should produce a white dot as it enters the tumor.

"We've demonstrated the ability to convect this therapeutic virus into the patient's brain tumor," said Aghi. "Over the next three hours we're going to watch that delivery unfold."

For Toner, the operating room success means that he will have far better odds of containing the tumor with the second stage of drug therapy, giving him the freedom to pursue the modest goals he's set up for himself as he fights the cancer, "So what do I want out of this? I want to be 32 years old again!"

ABC 7 has checked with the doctors. They tell us Toner is doing well and is beginning his drug regimen. Another note, the technology used to plot the surgery was also pioneered at UCSF.

by Tim Didion

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