Patients with a particularly aggressive type of brain cancer typically don't have many treatment options. But a new technique tested in mice and rats might provide a tool to combat the lethal tumors, known as glioblastomas. The strategy is to deliver growth-suppressing drugs directly and sustainedly to the tumor. If it works in humans, the technique could prolong the lives of some brain cancer patients, and it might be applicable to other types of cancer as well.
Glioblastomal tumors make up about one-quarter of the cases of brain cancer, and most patients survive for no more than 18 months past diagnosis. But the cancer's fast growth makes it a good candidate for tumor-shrinking compounds called angiogenesis inhibitors. These proteins, such as endostatin, inhibit the growth of blood vessels that the tumors need to grow and spread (ScienceNOW, 23 January 1997 ). Getting angiogenesis inhibitors into brain tumors and keeping them there, however, has been a problem.
In the January issue of Nature Biotechnology, two research teams report a solution. The basic approach is to implant a polymer matrix filled with genetically altered kidney cells that build antiangiogenesis proteins. The matrix helps prevent the immune system from rejecting the kidney cells. The group, led by neurologist Rona Carroll of Harvard Medical School in Boston, found that injecting the capsules underneath the skin of mice reduced the weight of tumors by 72% in 3 weeks. A team led by biologist Tracy-Ann Read of the University of Bergen, Norway, found that rats with brain tumors who received the capsules in their brains survived 84% longer than control rats.
If this type of treatment proved equally effective in humans, Read says, it could allow patients with glioblastomas to survive at least another year. "I would never proclaim it to be a cure," she cautions. Angiogenesis-inhibitor researcher Judah Folkman of Harvard Medical School says doctors might not have to operate at all if they could inject the capsules near the tumor. "It establishes a whole new approach to brain tumor treatment," Folkman says.