Green tea extract appears to keep cancer in check in majority of CLL patients
Mayo Clinic has conducted the first clinical studies of tea extract in cancer patients
CHICAGO -- An extract of green tea appears to have clinical activity with low toxicity in chronic lymphocytic leukemia (CLL) patients who used it in a phase II clinical trial, say researchers at Mayo Clinic.
The findings, to be presented Monday, June 7, during the annual meeting of the American Society of Clinical Oncology (ASCO), are the latest in a series of Mayo studies to show promise for use of the chemical epigallocatechin gallate (EGCG) -- the major component of green tea -- in reducing the number of leukemia cells in patients with CLL. Mayo first tested EGCG in a variety of laboratory assays about eight years ago, and it was found to reduce the survival of CLL leukemic cells. This laboratory finding was followed by a successful phase I clinical trial -- the first time green tea extract had been studied in CLL patients.
"Although only a comparative phase III trial can determine whether EGCG can delay progression of CLL, the benefits we have seen in most CLL patients who use the chemical suggest that it has modest clinical activity and may be useful for stabilizing this form of leukemia, potentially slowing it down," says Tait Shanafelt, M.D. , a Mayo Clinic hematologist and lead author of the study.
"These studies advance the notion that a nutraceutical like EGCG can and should be studied as cancer preventives," says Neil Kay, M.D. , a hematology researcher whose laboratory first tested the green tea extract in leukemic blood cells from CLL patients. "Using nontoxic chemicals to push back cancer growth to delay the need for toxic therapies is a worthy goal in oncology research -- particularly for forms of cancer initially managed by observation such as CLL."
Drs. Shanafelt and Kay caution that EGCG is not a substitute for chemotherapy. All of the patients Mayo tested with EGCG were early stage, asymptomatic CLL patients who would not otherwise be treated until their disease progressed. The extract was supplied by the National Cancer Institute (NCI) and Polyphenon E International for these initial clinical trials.
CLL is a blood cancer that is a hybrid between leukemia and lymphoma. Progression of the disease is measured by the quantity of leukemia cells in the blood and bone marrow as well as enlargement of lymph nodes due to infiltration by the leukemia cells. In the phase I study, published in May 2009 in the Journal of Clinical Oncology, researchers found that the blood lymphocyte (leukemia cell) count was reduced in one-third of participants, and that the majority of patients who entered the study with enlarged lymph nodes due to involvement by CLL saw a 50 percent or greater reduction in their lymph node size.
Article continues: http://www.eurekalert.org/pub_releases/2010-06/mc-gte060410.php
Link to published article in ASCO