Nanotech News

October 3, 2005

NCI Seminar Highlights Progress in Anticancer Nanomedicines

Though many observers believe that the application of nanotechnology in medicine is a recent phenomenon, "progress in the development of nano-sized hybrid therapeutics and nanosized drug delivery systems over the past decade has been remarkable," said Ruth Duncan, Ph.D., director of the center for polymer therapeutics at Cardiff University in Wales. Speaking at the most recent NCI-sponsored Nanotechnology Seminar Series, Duncan noted that routine clinical use and clinical development of nano-sized drug delivery vectors including liposomes, antibody conjugates, nanoparticles and polymer therapeutics as anticancer treatments is growing rapidly.

"Indeed, there is widespread anticipation that application of such nanotechnologies in medicine will bring the paradigm shift needed to improve both cancer diagnosis and therapy," she told the audience assembled at the Natcher Conference Center on the NIH campus. Dr. Duncan, who gave her guest lecture on Tuesday, September 28, 2005, noted that the NCI has been the worldwide leader in the effort to apply nanotechnology to cancer, and continues to be with its Cancer Nanotechnology Plan.

In her talk, Dr. Duncan reviewed some of the work that her group has done developing nanoscale polymer-drug combinations that can deliver water-soluble anticancer drugs in a targeted manner to tumors. These formulations are taken up into cells and held within tiny intracellular compartments known as lysosomes. There, enzymes break down, or cleave, a chemical linker that holds the drug onto the nanoparticle. Once this linker is cleaved, the drug molecule exits the lysosome and kills the cancer cell. Her group is currently working with doxorubicin and platinum compounds, each of which is already used in cancer therapy but with severe dose-limiting toxic effects. The hope is that delivering these compounds using nanoscale polymer particles could improve the safety profile of these drugs. Early results from human clinical trials with a polymer-doxorubicin formulation have, in fact, shown a five-fold reduction in toxicity compared to free doxorubicin.

Dr. Duncan's group is also working with polymeric nanomaterials to deliver more than one anticancer drug with the same nanoparticle. Early in vitro results of a 30 nanometer diameter nanoparticle combining doxorubicin and a drug known as an aromatase inhibitor have yielded surprising results. "We've seen a very significant increase in activity of the combination of the two drugs when we've tested this formulation on hormone-dependent tumor cells that are resistant to other drugs," she explained. If further preclinical results bear out these initial findings, this two-drug nanoparticle could be tested as a new therapy for women with metastatic breast cancer who are not responding to other forms of therapy.

In wrapping up her presentation, Dr. Duncan noted that nanotechnology is already making an impact in medicine, and the future holds great promise. Nonetheless, she cautioned against promising too much too soon. "I think the time line [for fully realizing the promise of nanotechnology in cancer therapy] will be longer than we expect."

Dr. Duncan's entire presentation can be viewed at the NIH's videocast archive site.
View webcast.