Clinical trials show that patients with glioblastoma multiforme, a particularly aggressive brain cancer, survived longer if they were treated with a vaccine followed by chemotherapy than did those patients treated with either the vaccine or chemotherapy alone. The finding continues recent progress in immune treatments for brain tumors (see “Brain Tumor Researchers Let Slip the Immune Cells of War,” May-June 2005 BrainWork).
The vaccine appears to kill off chemotherapy-resistant cells, leaving behind a population of cells that can be treated with chemotherapy, report John S. Yu, co-director of the Comprehensive Brain Tumor Program at Cedars-Sinai Medical Center in Los Angeles, and colleagues in the August issue of Oncogene.
To make the vaccine, dendritic cells were harvested from each patient’s blood, grown in a dish that contained proteins from glioblastoma tumors, and then injected back into the patient’s bloodstream. The process generates dendritic cells that display proteins to immune cells, instructing them to kill other cells that have those proteins on their surfaces, including tumor cells.
“What we show now is that one of the antigens being targeted by the vaccine is TRP-2 [tyrosinase-related protein-2],” Yu says. “When treated with the vaccine, patients had much less antigen in their subsequent tumor than they did before treatment.” Tumors that had less TRP-2 were more sensitive to chemotherapy than tumors with lots of TRP-2. The results suggest that targeting TRP-2 is important in treating glioblastomas.