Attacking Brain Cancer At Tumor Site Extends Survival
Brain Cancer Treatment
John Sampson, M.D., inserts four catheters into Meredith Hanson's skull and prepares to infuse an experimental drug into the cavity where her deadly brain tumor once sat. Just a few errant cancer cells lurking amidst her healthy brain tissue could quickly re-grow the tumor which he recently removed.
Over the next four days, Hansen chats with family and walks the hospital halls as a small pump slowly pushes the drug concoction directly into her brain. The new drug and its targeted attack provide the best possible chance of subduing Hansen's glioblastoma multiforme, a deadly brain cancer that claims its patients within a year of diagnosis.
Already, the experimental therapy has nearly doubled the expected median survival time for 24 patients enrolled in phase I and III clinical trials at the Duke Comprehensive Cancer Center's Brain Tumor Center.
Reaching the tumor is no small feat, given how glioblastoma wraps itself around normal cells just beyond the primary tumor mass. The catheters bypass healthy brain tissue and deliver the drug precisely to the sites of any remaining cancer cells that have been illuminated by magnetic resonance imaging. A forceful current sweeps the drug into the tumor space using computer generated imagery that directs the surgeon's placement of each catheter.
Once in place, the drugs target only those brain cells that express the IL13 receptor, a docking site on the surface of glioblastoma cells. Normal cells have no IL13 receptor so the drug is not allowed inside, sparing healthy tissue the toxic side effects of the drug.
Such extraordinary measures ensure that the drugs reach their intended target and bypass healthy brain cells. Traditional chemotherapy, delivered intravenously, must cross several barriers that limit its entry into the brain.
"Drugs that shrink tumors in other parts of the body often fail when we apply them to brain cancer, in part because so little of the drug permeates the blood-brain barrier and in part because the drugs indiscriminately attack healthy and cancerous cells, so we're limited to lower doses," said Sampson, a neurosurgeon at the Duke Brain Tumor Center. "Directly infusing drugs into the tumor cavity allows us to blanket the area with much higher concentrations of the drug