Nanotechnology - Not Lung Cancer Specific

[Kel M]

Nanotech delivers cancer treatment

Tuesday, June 21, 2005 Posted: 1137 GMT (1937 HKT)

(CNN) -- Scientists using nanotechnology have devised a way of delivering cancer drugs that could make them up to 10 times more effective in combating the killer disease.

By attaching a chemotherapeutic drug to manmade nanoparticles, the team of researchers at the University of Michigan were able to smuggle it inside cancerous cells, delaying the growth of tumors in mice by up to 30 days -- the equivalent of three years in a human.

Professor of biologic nanotechnology James Baker, who led the research, said that the treatment might eventually turn cancer into a chronic but treatable condition.

The study, which is published in the current edition of the Cancer Research journal, is one of the first successful therapeutic uses of nanotechnology on living animals.

"This is the first study to demonstrate a nanoparticle-targeted drug actually leaving the bloodstream, being concentrated in cancer cells, and having a biological effect on the animal's tumor," said Baker.

"We're very optimistic that nanotechnology can markedly improve cancer therapy."

Baker said that the technique was based on a Trojan Horse principle.

The vehicle delivering the drug is a manmade polymer molecule called a dendrimer that measures less than five nanometers in diameter, or five billionths of a meter, making it small enough to pass through cell membranes.

The dendrimer's tree-like structure allows scientists to attach other molecules to its branches.

Some of these are loaded with the cancer treatment drug methotrexate. But others carry folic acid, which cells -- and particularly cancer cells -- need to replicate.

By baiting them with the folic acid, the cancer cells are tricked into also accepting the methotrexate, which then poisons them.

The dendrimer is then flushed out of the bloodstream via the kidneys.

The nanoparticle-based therapy was 10 times more effective at delaying tumor growth in mice and less toxic to other cells and tissue than conventional treatment.

In chemotherapy, the drug is diffused across a cell membrane before getting inside cancerous cells. That requires a high concentration of drugs, which can damage healthy cells as well.

If the toxicity problem can be overcome, the method may allow for the delivery of other, more powerful chemotherapy drugs and also enable more personalised cancer treatment, tailored for the specific requirements of individual patients.

"Targeting drugs directly to cancer cells reduces the amount that gets to normal cells, increases the drug's anti-cancer effect and reduces its toxicity. By improving the therapeutic index of cancer drugs, we hope to turn cancer into a chronic, manageable disease," said Baker.

Further research is due to be undertaken to determine the maximum therapeutic dose, with the first human clinical trials scheduled to begin within two years.

Emma Knight of the Cancer Research charity told the New Scientist magazine that the results of the study were "very interesting."

"They show that nanotechnology has the potential to increase the effectiveness of modern-day cancer drugs by specifically targeting them to cancer cells," she said.