Drugs that Deliver
Chemotherapy often falls short of achieving its full impact because the drugs diffuse in and out of tumors too rapidly. That's because the small size of current chemotherapy drugs -- which typically have a molecular weight in the 300 to 600 range -- allow them to be readily excreted through the kidneys before their anti-cancer effects are fully achieved.
If you balance the ability of drug to penetrate tumors with its staying power once inside, you can get optimal drug concentration.
Biomedical engineering professor Ashutosh Chilkoti and colleagues at Duke Medical Center have devised a blueprint for increasing anti-cancer drugs' effectiveness and lowering their toxicity by attaching the equivalent of a lead sinker onto the drugs. Drugs boosted to an optimal macromolecular weight between 40,000 and 70,000 penetrate and accumulate inside tumors more effectively, they reported last year in the Journal of the National Cancer Institute.
The National Institute of Biomedical Imaging and Bioengineering-funded work could also reduce chemotherapy's toxicity to healthy tissue because the large molecules cannot easily permeate normal blood vessels, but do so readily through the leaky blood vessels typically found in tumors. As a result, normal tissue receives less of the drug than does the tumor.