Contact: Meghan Lewit
University of Southern California
USC study finds that green tea blocks benefits of cancer drug
The widely used supplement renders a specific drug
used to treat multiple myeloma and mantle cell lymphoma ineffective in
Contrary to popular assumptions about the
health benefits of green tea, researchers at the University of Southern
California (USC) have found that the widely used supplement renders a
cancer drug used to treat multiple myeloma and mantle cell lymphoma
completely ineffective in treating cancer.
The study, which
found that a component of green tea extract (GTE) called EGCG destroys
any anticancer activity of the drug Velcade in tumor-bearing mice, will
be published in a future print edition of the journal,
Blood. It is now available online at the journal's pre-publication First Edition website.
finding that GTE or EGCG blocked the therapeutic action of Velcade was
completely unexpected," says lead author Axel H. Schönthal, PhD,
associate professor in the Department of Microbiology and Immunology at
the Keck School of Medicine of USC. "Our hypothesis was that GTE or
EGCG would enhance the anti-tumor effects of Velcade, and that a
combination of GTE with Velcade (or EGCG with Velcade) would turn out
to be a superior cancer treatment as compared to treatment with Velcade
Herbal remedies, including green tea, have become a
popular remedy for cancer patients dealing with side effects of
chemotherapy. However, these supplements are unregulated and, for most,
their beneficial and/or detrimental effects have not been qualified
Using preclinical models and tumor-bearing
mice, the researchers found that the unusually effective blockage of
Velcade's therapeutic activity was based on the chemical interaction
between molecules. The EGCG molecule and the Velcade molecule were able
to form chemical bonds, meaning that the Velcade molecule could no
longer bind to its intended target inside the tumor cells.
trials to verify these results in humans would be highly unethical to
conduct, because of the predictably unfavorable outcome. Nevertheless,
the researchers expect the results of the study to be applicable to
"The most immediate conclusion from our
study is the strong advice that patients undergoing cancer therapy with
Velcade must avoid green tea, and in particular all of its concentrated
products that are freely available from health food stores," says
Schönthal. "It is important to spread this message to health care
providers who administer Velcade to patients."
points out that for patients on Velcade, supplementing with green tea
products should reduce the burden of harsh side effects—which might be
attractive to the patient, but comes at a high cost.
in addition to not being able to attack tumor cells, Velcade would be
unable to cause side effects either," he says. "As a result, the
patient would feel a lot better and conclude that the consumption of
GTE helped cope with side effects—while in reality, Velcade simply
wasn't active in the first place."
The research findings are
part of a larger project run by the team called "Yin-Yang Properties of
Green Tea Extract in Combination Cancer Chemotherapy: From
Encouragingly Beneficial to Dangerously Detrimental."
the combination of GTE or EGCG with Velcade is an example of
'dangerously detrimental,' "Schönthal says. "But we are also studying
another well-established chemotherapeutic drug, where the inclusion of
EGCG appears to yield an 'encouragingly beneficial' outcome, which is
more in line with our original expectation that GTE should be
beneficial, not detrimental."
The study was funded by the Multiple Myeloma Research Foundation.
B. Golden, Philip Y. Lam, Adel Kardosh, Kevin J. Gaffney, Enrique
Cadenas, Stan G. Louise, Nicos A. Petasis, Thomas C. Chen, Axel H.
Schönthal. "Green Tea Polyphenols Block The Anticancer Effects of
Bortezomib And Other Boronic Acid-Based Proteasome Inhibitors."