Prof hopes tiny packages will have big impact in treating ill
Tiny packages carrying a chemotherapy drug and designed to attach themselves and deliver the treatment directly to tumor cells have shown promising results in mice implanted with human prostate cancer.
Jianjun Cheng, a University of Illinois professor who was part of the team that developed the technique, hopes to be able to use something like it to deliver gene-related therapies as well.
That could take the form of delivering replacement DNA for a repair job where a breakdown in the basic genetic material has led to cancer and other diseases.
It also might include delivering small interfering RNA, a recently discovered type of catalyst in gene deactivation, to turn off, in effect, overactive genes that are making a patient sick.
In the mouse and prostate cancer study, the researchers mixed a chemotherapy drug, a polymer and a nucleic acid that naturally binds to cancer cell receptor proteins to create a three-part, nano-scale treatment delivery system. The treatment eliminated the human prostate cancer implanted in the mice.
The results attracted attention from cancer specialists at the European Cancer Conference in Paris last month, where they were reported by Omid Farokhzad, a Harvard Medical School professor.
Cheng, a materials science and engineering professor, developed the technique with Farokhzad and MIT scientists Benjamin Teply and Robert Langer before joining the UI faculty this fall.
He also has worked as a senior scientist at Insert Therapeutics, a biopharmaceutical company, but was attracted by the UI's highly rated materials science program and the opportunity to set up his own academic research lab and to teach.
Cheng said the polymer nanoparticles – polymers are small molecules conjoined to create a larger, long molecule chain – act as a delivery vehicle for the chemotherapy drug and also as a slow-release container. The polymer eventually degrades completely and is absorbed or excreted by the body.
"It's (a Food and Drug Administration)-approved polymer, so it's very safe to use in humans," said Cheng, whose expertise is materials chemistry, particularly biomaterials.
The nano-scale packages – a nanometer is a billionth of a meter – were designed to be injected through the tail vein, in the case of mice, travel to and enter tumor cells by attaching to the receptor protein, and slowly release chemotherapy drug molecules in the cancer cells to kill them. Cheng said an injection can keep working for 100 days.
Since the package attaches specifically to tumor cells and releases the drug in a controlled fashion, it does less damage to surrounding tissue as well, he said.
Cheng stopped short of saying the development means targeted tumor treatment, a long-standing goal, is about to become a reality. But the technique has promise, he said.
"We're on the way," Cheng said. "But I think it's too early to tell if we're getting close. We see some hope based on our data."
The mice are a good model for humans in this kind of study, Cheng said. He cautioned that the comparison isn't absolute, however.
At the UI, Cheng and colleagues are working on different types of delivery vehicles for DNA and RNA therapy.
Cheng said they also want to develop packages capable of responding to cell signals like changes in pH balance, a cell's acidity or alkalinity. The idea is that such a system might remain dormant under some cellular conditions, detect changes in the environment and release a drug if needed in response.
In addition, they're working on the proper chemistry to promote self-assembly of such packages, which are too tiny to manipulate and assemble by hand.