Peptide-Doxorubicin a Potent Anti-Tumor Cocktail in Mice, La Jolla, Jan. 19, 1998
NEW YORK (Reuters) -- Drugs which piggy-back on proteins may be able to destroy cancer cells while causing little harm to healthy tissue, according to research appearing in this week's issue of the journal Science.
Investigators at the Cancer Research Center of The Burnham Institute in La Jolla, California, say their discovery could help doctors minimize the painful side effects of chemotherapy, and "...markedly improve cancer treatment."
The powerful drugs used to combat cancer can also wreak havoc on the function of organs such as the heart, kidney and liver, resulting in side effects such as fatigue, weight loss, and nausea.
But the La Jolla researchers have found a novel means of targeting drugs at tumor cells alone, thus avoiding harm to healthy cells.
They have discovered two types of peptides (protein fragments) that migrate specifically to the endothelial cells lining the blood vessels in cancerous tissue.
The researchers coupled the anti-cancer drug Doxorubicin (commonly known as "dox") to both of the peptides. This allowed the drug to effectively "hitch a ride" to its intended target, the tumor.
In studies on cancer-bearing mice, the authors found that mice treated with the peptide-dox combination outlived mice treated with dox alone by more than six months. And they say that the tumors of mice treated with peptide-dox showed extensive shrinkage, "whereas those signs were not observed in any of the control (dox-only) groups."
The peptide-dox combination was also found to be much less toxic to the livers and hearts of those mice placed on the regimen, compared with the organs of mice treated with dox alone. The investigators believe that the accumulation of the peptide-dox compound within tumor tissue "appeared to have sequestered the... drug, thereby reducing its toxicity to other tissues."
They say the therapy should prove just as effective in humans. Blood vessel cells may, in fact, be a kind of "Achilles' heel" when it comes to tumor destruction: the researchers say "it has been estimated that elimination of a single endothelial cell can inhibit the growth of 100 tumor cells." They add that blood vessel cells are also less likely to undergo genetic mutation, reducing the risk that they might develop resistance against specific cancer-fighting compounds. SOURCE: Science (1998;279:377-380)
** POSTED JANUARY 26, 1998 **