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, presented Monday, June 7, during the annual meeting of the American Society of Clinical Oncology (http://www.asco.org/) (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.