Killing Cancer – New Brain Cancer Treatment Targets Tumors


NARRATOR: This year in the United States, nearly 70,000 people will be diagnosed with brain tumors. Of those, nearly 12,000 will be diagnosed with glioblastoma multiforme. DR. MARK DEWHIRST: The problem is that virtually all the patients die. So it’s a death note if you have it. NARRATOR: Glioblastoma multiforme is a particularly deadly brain cancer. It kills more than half its victims within one year, more than 90% within three years. DR. STEFAN BOSSMANN: If you want to beat cancer and especially gliomas, you cannot dangle your feet in the water and say, “In principle, we can do this.” We are in for making a difference. NARRATOR: As a professor of chemistry, Stefan Bossmann may be an unlikely cancer researcher, as is his Kansas State colleague Deryl Troyer, an expert in veterinary medicine, but together, these two are blazing a trail to better the odds of surviving glioblastoma. DR. STEFAN BOSSMANN: Classic chemotherapy delivers about 1% of the drug to the tumor and classic nanotherapy, about 10%. So obviously, that’s not enough. NARRATOR: Bossmann and Troyer are developing a new cell-based therapy that could deliver more than 50% of prescribed anti-cancer drugs to brain tumors. Their method attempts to solve one of brain cancer treatment’s biggest challenges: getting enough anti-cancer medicine past the blood-brain barrier, a protective network of blood vessels and cells that filters foreign substances from flowing to the brain. The problem is the barrier also filters anti-cancer drugs, causing medications meant to be beneficial to instead harm otherwise healthy cells, but Bossmann and Troyer’s plan uses a kind of Trojan horse to slip medications across the blood-brain barrier. DR. DERYL TROYER: So the idea that we are pursuing is to use cells as cargo ships to ferry therapeutic drugs so that they go only to tumors and don’t cause a lot of the side effects that therapy often causes. NARRATOR: Their cargo ship of choice? The patient’s own white blood cells. They move across the blood-brain barrier and target tumors as a natural function of the immune system. DR. DERYL TROYER: The idea is that cells can respond to signals coming from the tumor, travel to the tumor, and then migrate actively into the interior of the tumor. NARRATOR: But for white blood cells to be effective cargo ships, they have to carry the anti-cancer drugs placed within them safely and that’s where Bossmann and Troyer’s research comes in. Funded by a grant from the National Science Foundation, they’re using material science to develop a new class of drug-carrying containers. They’re called protease activatable polymer-caged liposomes that travel inside white blood cells. DR. STEFAN BOSSMANN: So the major problem is to get a drug which is really toxic to the tumor cell and not to any other cells. NARRATOR: Liposomes are artificial bubbles inside a cell that can be used to carry medicine. Bossmann and Troyer are developing self-assembling cages that wrap around these artificial bubbles and keep them safely contained during transport. DR. DERYL TROYER: The cage that surrounds these liposomes is designed so that it can only be released when the cell tells it to open. When the cell reaches the tumor, then the cell activates enzymes or we can make the cell activate enzymes that will open the cage and release the drug. DR. STEFAN BOSSMANN: So this is a typical materials problem and material science will be able to make a lot of anti-cancer drugs very effective, which are not currently used because they are too toxic when you inject them in the patient’s bloodstream. NARRATOR: The team has successfully developed test liposomes and used breast cancer in mice to prove tumors are capable of attracting large numbers of white blood cells. Bossmann and Troyer anticipate human clinical trials in the next few years. DR. MARK DEWHIRST: Brain tumors are extremely difficult to cure and there are many kinds of innovative therapies that have gone into the trash can. So if they can get adequate amount of drug in there to prolong somebody’s life, that’s a win-win in a brain tumor patient. NARRATOR: The goal is for these advanced liposome cages to help brain cancer patients live longer and in the face of an otherwise bleak prognosis, give patients and their doctors a glimmer of hope. ♫MUSIC♫