Toad Venom May Slow Cancer Progression

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People with cancer will not need to kiss a toad to get possible benefits from this amphibian. Researchers from The University of Texas M.D. Anderson Cancer Center report that huachansu, a Chinese medicine made from dried toad venom, may slow progression of cancer in some patients.

The Phase I clinical trial was a collaborative effort between M.D. Anderson and Fudan University Cancer Hospital in Shanghai, and it was the first clinical trial to evaluate the relationship between huachansu dose and toxicity. The popular Chinese toad venom remedy is used widely throughout China for treatment of patients who have liver, lung, colon, and pancreatic cancer.

In a 2008 study, published in the World Journal of Gastroenterology, researchers found that huachansu along with the drug combination gemcitabine-oxaliplatin resulted in a cancer control rate of 65.2 percent (partial response plus stable disease) in patients with gallbladder cancer. The toad venom medication has also demonstrated a response rate of 10 percent in a study of patients with liver cancer and a 16 percent rate in a lung cancer study. Both studies also involved chemotherapy.

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According to the National Cancer Institute, the traditional Chinese toad venom medicine consists of a water soluble Bufo toad skin extract that contains various cardiac glycosides that have potential antineoplastic (stops tumors) and antiangiogenic (stops tumors from making blood vessels) properties. Although it not yet known how huachansu works, one idea is that it may induce interruption of the cell cycle and cell death by suppressing the activity of certain proteins.

In the new study, the researchers administered doses of the toad venom drug intravenously at doses ranging from 10 milliliters per meter squared of body mass (10 mL/m2) up to 90 mL/m2 to patients who had liver, nonsmall cell lung, or pancreatic cancer. (The typical dose used in China is 15 mL/m2.) The patients received two cycles of therapy with each cycle consisting of 14 days of treatment followed by seven days off.

Although the doses used in the new study were up to eight times greater than the conventional doses used in China, the researchers noted only low toxicities or side effects. Of the 15 patients who completed the treatment, six (40 percent) had no cancer progression for a median of six months. One patient had a 20 percent reduction in tumor mass for more than 11 months. Even though none of the patients in this study achieved partial or complete response (defined as a reduction of disease by 30 percent or more), the achievement of stable disease in some patients and the occurrence of only low toxicities or side effects were sufficient to warrant further clinical trials of the toad venom medication in more cancer patients.

SOURCES:
Hang L. Henan Journal of Oncology 2002; 15
Zhongjie S et al. Zhong Liu Fang Zhi Za Zhi 2002; 29:67-69
MD Anderson Cancer Center news release, September 24, 2009
Meng Z et al. Cancer 2009 Aug 21
Qin TJ et al. World of Gastroenterology 2008; 14(330: 5210-16

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