Glioblastoma is an aggressive form of brain cancer that kills most patients within two years of diagnosis. In tests on mice last year, a team at the University of North Carolina at Chapel Hill showed that adult skin cells could be transformed into stem cells and used to hunt down the tumors. Building on that, they've now found that the process works with human cells, and can be administered quickly enough to beat the ticking time-bombs.
Treatments for glioblastoma include the usual options of surgery, radiation therapy and chemotherapy, but none of them are particularly effective. The tumors are capable of spreading tendrils out into the brain and it can grow back in a matter of months after being removed. As a result, the median survival rate of sufferers is under 18 months, and there's only a 30 percent chance of living more than two years.
"We desperately need something better," says Shawn Hingtgen, the lead researcher on the study.
To find that something better, last year the scientists took fibroblasts – a type of skin cell that generates collagen and connective tissue – from mice and reprogrammed them into neural stem cells. These stem cells seek out and latch onto cancer cells in the brain, but alone are powerless to fight the tumor. To give them that ability, the scientists engineered them to express a particular cancer-killing protein. The result was mice that lived between 160 and 220 percent longer.
The next step was to test the process with human cells, and in the year since, the team has found that the results are just as promising. The technique differs slightly when scaled up to humans. The patient would be administered with a substance called a prodrug, which by itself does nothing, until it's triggered. The stem cells are engineered to carry a protein that acts as that trigger, activating the prodrug only in a small halo around itself instead of affecting the entire body. That allows the drug to target only a small desired area, ideally reducing the ill side effects that treatments like chemotherapy can induce.
Importantly, the technique can be administered quickly, to give the patients the best chance at survival.
"Speed is essential," says Hingtgen. "It used to take weeks to convert human skin cells to stem cells. But brain cancer patients don't have weeks and months to wait for us to generate these therapies. The new process we developed to create these stem cells is fast enough and simple enough to be used to treat a patient."
The treatment is an important step, but there's still a long way to go.
"We're one to two years away from clinical trials, but for the first time, we showed that our strategy for treating glioblastoma works with human stem cells and human cancers," says Hingtgen. "This is a big step toward a real treatment – and making a real difference."
The research was published in the journal Science Translational Medicine.
