News Story Bloomberg Press, June 9, 2004
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Scientists Discover More Effective Chemotherapy
Delivery
2004-06-09 13:02 (New York)
By Geraldine Ryerson-Cruz
June 9 (Bloomberg) -- Cancer researchers have found a way to
deliver chemotherapy drugs right to tumors without injuring
healthy tissue, by targeting a certain protein in malignant
growths, according to a study of rats.
Researchers discovered the annexinA1 protein in the walls of
blood vessels that supply tumors and cloned antibodies that bind
only to that protein. Attaching the antibodies to chemotherapy
drugs or radioactive isotopes might deliver more medicine or
radiation to tumors, according to research to appear in the June
10 Nature journal.
The findings may lead to more-powerful cancer therapies with
fewer side effects, researchers led by Jan E. Schnitzer at Sidney
Kimmel Cancer Center in San Diego said. While drug developers
have made compounds that target specific cancer types
effectively, getting enough medicine into them is difficult.
``What we've done is adjust the bull's-eye from the tumor
surface to the part of the tumor we know has access to anything
you put in the blood,'' or the proteins lining blood vessels,
Schnitzer said in a telephone interview. The findings probably
would apply to humans, he added.
Chemotherapy generally kills fast-growing cells, both
healthy and cancerous. Attacking healthy cells in the skin,
mouth, intestines and bone marrow, leads to debilitating side
effects.
About 34 percent of the radioactive treatment plus the
cloned antibodies that was injected in rats accumulated in tumors
within two hours. A treatment using another kind of antibody that
attaches to a receptor for ``vascular endothelial growth
factor,'' led to 6.4 percent accumulation in tumors.
Possibility of Remission
Eighty percent of the rats treated with a single injection
using the new technique survived eight days or longer, compared
with as much as seven days for untreated rats in the study. One
of the rats is still alive, signaling that the annexinA1 antibody
injections might cause remission of advanced cancer, the
researchers said.
The researchers plan to study whether the technique would be
effective in humans.
In the next step, ``we have to decide what toxic warhead to
put on this delivery system,'' Schnitzer said.
There are more than a million proteins in the human body,
and the research team's new method for scanning them can be used
to winnow out less-promising candidates and speed the discovery
process, the scientists said in the publication.
The research was funded by donors including the National
Institutes of Health, the National Cancer Institute and the
California Breast Cancer Research Program. The study was
published on Nature's Web site today.
--Editor: Barry.
To contact the reporter on this story:
Geraldine Ryerson-Cruz in New York at (1) (212) 318-2394 or
gryerson@bloomberg.net.
To contact the editor responsible for this story:
Robert Simison at (1) (202) 624-1812 or rsimison@bloomberg.net.
