FDA Prepares for Nanomedicine Revolution
Atomic-Scale Nanoparticles Promise New Era in Medicine
What Is Nanomedicine? continued...
"We have not been able to answer all of the questions about a lot of important diseases -- grievous diseases such as diabetes, cardiovascular disease, diseases of aging, cancer. All these diseases have some genetic underpinning, but the genetic role is partial," says Marth. "What nanomedicine is able to do is to begin to identify and interrogate those processes which are outside our genetic inheritance."
That's only part of the story. Nanotechnology also offers powerful new tools to treat disease.
The FDA already has approved two cancer drugs based on nanotechnology: Abraxane and Doxil, which package cancer drugs into nanoscale lipid droplets and allow higher chemotherapy doses with fewer side effects.
Second-generation drugs of this type will carry nanoparticles on their surfaces that not only target the drugs to cancer cells, but also allow them to penetrate deep into tumors. The FDA has given the green light to clinical trials of Cornell dots -- nanoscale silicon cages that carry nanoparticles to tumor cells.
Marth says that nanomedicine will speed the discovery of biomarkers that identify diseased cells. Once these biomarkers are found, they can be used to bind therapeutic nanoparticles only to the cells that need them, leaving normal cells alone.
Bao's team is pioneering another approach: using nanoparticles to repair genetic mutations. Their first target will be the mutation that causes sickle cell disease.
"We are trying to develop nanodevices to fix this mutation," Bao says. "We use a nanoscissors -- technically a zinc finger nuclease -- to cut the DNA at a pre-described location. At the same time, we supply a piece of DNA that has no mutation. In repairing the DNA cut, the cell actually uses the template we supply."
Is Nanomedicine Safe?
A major task for the FDA will be to set guidelines for demonstrating that new nanomedicines are safe. But Marth says there are both toxic and nontoxic approaches to nanomedicine.
"We will have to do clinical trials, but we are not adding poisonous materials to the body," he argues. "The way forward is to take natural products, rearrange them in ways that do new things, but allow them to be degraded normally in the body."
Even so, Bao says the FDA guidance will be important, as materials that behave one way on a normal scale can behave quite differently at a nanoscale.
"There might be some unique features of nanoparticles that induce some toxic effects," Bao suggests. "If they could get into the body, stay in the cells, not be cleared, there might be some harmful effects down the road, and we need to understand that. We do not think the particles we use have any intrinsic toxicity, but we need to know this for sure."