Baited molecule fights cancer

Many teams of researchers are working on ways to use nanotechnology to deliver anticancer drugs directly to cancerous tissue.

Researchers from the University of Michigan have brought the field a step forward. They showed in live mouse trials that it is possible to concentrate anticancer drugs in certain tumors by attaching an anticancer drug and folic acid to tiny bits of polymer and injecting the mix into the bloodstream.

Key to the method is that the nanoparticles are small enough to escape the bloodstream and get into cancer cells. The modified dendritic, or branched, polymers that carry the drugs are less than five nanometers in diameter. In contrast, a red blood cell is 5,000 nanometers in diameter.

In the researchers' experiments, the nanoparticles and cancer drug concentrated in tumors after four days. Delivering the drug to the mice this way increased the antitumor activity of the drug and dramatically decreased the drug's toxicity, according to the researchers.

The nanoparticles concentrate in cancers that have a high affinity for folic acid. Brain, breast, endometrium, head, kidney, lung, myeloid, neck, and ovary cancers all take in a lot of folic acid. Scientists have chemically linked folic acid to anticancer drugs before, but these previous methods did not work well because they reduced the effectiveness of the anticancer drug and reduced the ability of the cancer cells to take up the folic acid, according to the researchers.

The researchers' method could potentially be used to deliver many types of therapeutic drugs to nearly any type of cell, according to the researchers. It could also be used to deliver imaging agents, or substances that allow certain cells to show up better when medical images are taken.

The method could be ready for testing in humans within 18 months, and could be through the trials in five to six years, according to the researchers. The work appeared in the June 15, 2005 issue of Cancer Research (Nanoparticle Targeting of Anticancer Drug Improves Therapeutic Response in Animal Model of Human Epithelial Cancer).