Search-and-destroy drugs attack lethal brain cancer

When diagnosed with glioblastoma, a deadly form of brain cancer that killed U.S. Sen. Ted Kennedy (D-MA) in 2009, doctors and patients have limited options to combat the tumors. They spread widely in the brain tissue and are often too numerous to surgically remove or attack effectively with chemotherapy and radiation. Scientists now report that they've developed a multi-faceted drug that showed great promise in homing in on and destroying the lethal brain tumors in mice.

Their drug is a Swiss army knife of sorts against glioblastoma, with three distinct parts all linked together. It's got a peptide--or short protein--that steers the drug to the tumors and binds specifically to cancer cell surfaces, another peptide that triggers cellular death by attacking the power centers of cells, and a nanoparticle that serves as both an imaging agent to view the tumors with MRI and a cancer killer. When given to one group of mice with glioblastomas, the treated mice survived longer than untreated ones. And in a second group of mice with the brain tumors, the drug cured 9 of 10 mice and extended the survival of the other mouse, according to a release.

Of course, curing cancer in mice often doesn't translate into a breakthrough in human treatment. Yet scientists behind the project, which involved Sanford-Burnham Medical Research Institute (Sanford-Burnham) and the Salk Institute for Biological Studies, pointed out some key characteristics of the new drug that could make it an effective and non-toxic remedy for the brain cancers.

The prognosis for people diagnosed with glioblastoma is often poor and patients often die in less than a year, meaning there's plenty of room to prolong the survival of these patients with new therapies. Kennedy's battle with the cancer lasted for less than two years.

"This is a unique nanosystem for two reasons. First, linking the cell-killing peptide to nanoparticles made it possible for us to deliver it specifically to tumors, virtually eliminating the killer peptide's toxicity to normal tissues. Second, ordinarily researchers and clinicians are happy if they are able to deliver more drugs to a tumor than to normal tissues. We not only accomplished that, but were able to design our nanoparticles to deliver the killer peptide right where it acts-the mitochondria, the cell's energy-generating center," Dr. Erkki Ruoslahti, senior author of the study and a professor in both Sanford-Burnham's NCI-designated Cancer Center in La Jolla and the Center for Nanomedicine, said in a statement.

The study was published this week in the journal Proceedings of the National Academy of Sciences.

- here's the release