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May 27, 2009

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Green tea extract reported to show promise against leukemia

May 27, 2009
Courtesy Mayo Clinic
and World Science staff

Sci­en­tists are re­port­ing pos­i­tive re­sults in early leu­ke­mia clin­i­cal tri­als us­ing the chem­i­cal epi­gal­lo­cat­echin gal­late, a sub­stance in green tea. 

“The ma­jor­ity of in­di­vid­u­als who en­tered the study with en­larged lymph nodes saw a 50 per­­cent or great­er de­cline in their lymph node size,” said Tait Shan­a­felt, a hema­tolo­g­ist at the May­o Clin­ic in Roch­es­ter, Minn., and lead au­thor of the stu­dy. More­o­ver, “pa­tients tol­er­ated the green tea ex­tract at very high dos­es.” 

Sci­en­tists are re­port­ing pos­i­tive re­sults in early leu­ke­mia clin­i­cal tri­als us­ing the chem­i­cal epi­gal­lo­cat­echin gal­late, a sub­stance in green tea. (Image cour­tesy A. Rad­dia)

The find­ings ap­peared on­line May 26 in the Jour­nal of Clin­ical On­col­o­gy.

The find­ings tested the chem­i­cal’s ef­fect on pa­tients with chron­ic lym­pho­cyt­ic leu­ke­mia, the most com­mon type of leu­ke­mia in the Un­ited States. Cur­rently it has no cure.

The ill­ness starts with a muta­t­ion in a sin­gle blood cell called a lym­pho­cyte. Over time, the al­tered cells mul­ti­ply and re­place nor­mal lym­pho­cytes in the bone mar­row and lymph nodes, or­gans that are found all over the body and act as fil­ters or traps for for­eign par­t­i­cles. The lymph nodes be­come en­larged as a re­sult.

About half of pa­tients with early stage dis­eases have an ag­gres­sive form of the dis­ease that leads to early death, re­search­ers said. They hope the green tea ex­tract can sta­bi­lize early-stage pa­tients or per­­haps work in com­bina­t­ion with oth­er ther­a­pies to im­prove their ef­fectiveness.

Green tea is made with the leaves of Ca­mel­lia sine­sis, a shrub na­tive to Asia.

In the tri­al, 33 pa­tients re­ceived varia­t­ions of eight dif­fer­ent oral doses of Polyphe­non E, a pro­pri­e­tary com­pound whose pri­ma­ry ac­tive in­gre­di­ent is epi­gal­lo­cat­echin gal­late. Doses ranged from 400 to 2,000 mil­ligrams twice a day. Re­search­ers de­ter­mined that they had not reached a max­i­mum tol­er­ated dose, even at 2,000 mg twice per day.

The re­search has moved to the sec­ond phase of clin­i­cal test­ing in a fol­low-up tri­al, al­ready fully en­rolled, in­volv­ing roughly the same num­ber of pa­tients. All will re­ceive the high­est dose ad­min­is­tered from the pre­vi­ous tri­al.

The stud­ies are part of a mul­ti­year proj­ect that be­gan with tests of the green tea ex­tract on can­cer cells in the lab­o­r­a­to­ry of May­o hema­tolo­g­ist Neil Kay, a co-au­thor of the stu­dy. Af­ter the re­search showed dra­mat­ic ef­fectiveness in kill­ing leu­ke­mia cells, sci­en­tists said, the find­ings were ap­plied to stud­ies on an­i­mal tis­sues and then on hu­man cells in the lab.

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Scientists are reporting positive results in early leukemia clinical trials using the chemical epigallocatechin gallate, a substance in green tea. “The majority of individuals who entered the study with enlarged lymph nodes saw a 50 percent or greater decline in their lymph node size,” said Tait Shanafelt, hematologist at the Mayo Clinic in Rochester, Minn., and lead author of the study. Moreover, “patients tolerated the green tea extract at very high doses.” The findings appear today online in the Journal of Clinical Oncology. The findings tested the chemical’s effect on patients with chronic lymphocytic leukemia, the most common type of leukemia in the United States. Currently it has no cure. The illness starts with a mutation in a single blood cell called a lymphocyte. Over time, the altered cells multiply and replace normal lymphocytes in the bone marrow and lymph nodes, organs that are found all over the body and act as filters or traps for foreign particles. The lymph nodes become enlarged as a result. About half of patients with early stage diseases have an aggressive form of the disease that leads to early death, researchers said. They hope the green tea extract can stabilize early-stage patients or perhaps work in combination with other therapies to improve their effectiveness. Green tea is made with the leaves of Camellia sinesis, a shrub native to Asia. In the trial, 33 patients received variations of eight different oral doses of Polyphenon E, a proprietary compound whose primary active ingredient is epigallocatechin gallate. Doses ranged from 400 to 2,000 milligrams twice a day. Researchers determined that they had not reached a maximum tolerated dose, even at 2,000 mg twice per day. The research has moved to the second phase of clinical testing in a follow-up trial, already fully enrolled, involving roughly the same number of patients. All will receive the highest dose administered from the previous trial. The studies are part of a multiyear project that began with tests of the green tea extract on cancer cells in the laboratory of Mayo hematologist Neil Kay, a co-author of the study. After the research showed dramatic effectiveness in killing leukemia cells, scientists said, the findings were applied to studies on animal tissues and then on human cells in the lab.