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PC-SPES (PDQ®): Complementary and alternative medicine - Health Professional Information [NCI] - History

In 1997, the herbal formula for PC-SPES was patented in the United States.[1] A company, BotanicLab (Brea, California), was formed to produce, distribute, and sell the product. PC-SPES was sold through the BotanicLab Web site (the Web site was taken down after PC-SPES was recalled) and through selected distributors. Anecdotal information about the product and its positive effects was widely circulated on the Internet through Web sites that informed prostate cancer patients about new developments in treatment. At the same time, the published papers were being read by the scientific community, and the findings were presented at various conferences. As a result, clinicians and researchers began looking at PC-SPES as one of the first viable treatments to come out of the alternative medicine community.

The manufacturing process for PC-SPES has been described by the manufacturer as follows: extracts of raw plant material were obtained from the specified plants, which were grown in particular geographic regions in China and harvested at certain times of the year to reduce the natural variation inherent in any biological product. The extracts were shipped to the United States, where high-performance liquid chromatography (HPLC) was used to monitor the key active compounds—which are believed to be directly related to the clinical effects—for batch-to-batch reproducibility. Activity-related biomarkers were kept in a constant concentration from lot to lot. A commercial testing laboratory (Truesdail Laboratory; Tustin, California) was used to guarantee that each batch was free from contamination with heavy metals, pesticides, microorganisms and products, and prescription drugs. Each lot was standardized by an anticancer bioassay for an effective dose of 50% in vitro inhibition of cell growth using human LNCaP cells for androgen-dependent (AD) prostate cancer and DU-145 cells for androgen-independent (AI) prostate cancer. The powder was then encapsulated, bottled, labeled, and sterilized at the BotanicLab facility.[2]

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In 2001, allegations that PC-SPES contained the synthetic estrogen diethylstilbestrol (DES) started to appear on e-mail listservs used by prostate cancer patients and in online newsletters. Prostate cancer patients who were taking PC-SPES noticed that their recent medication was not as effective as the previous batches.[3] A sample of PC-SPES submitted to a testing laboratory by BotanicLab in August 2001 found no DES. BotanicLab posted the letter from the laboratory on their Web site, claiming that PC-SPES contained no DES. However, in other tests of six different lots of PC-SPES received from two different sources in August 2001, Rocky Mountain Instrumental Laboratory found varying amounts of DES in three lots. More tests done by the California Department of Health Services in February 2002 did not find DES but did find warfarin, a prescription drug used as a blood thinner.[4]

The presence of a synthetic estrogen such as DES was suspected early in the clinical use of PC-SPES after reports in the literature discussed the mixture's estrogen-like ability to lower prostate-specific antigen (PSA) levels in AD prostate cancer patients. In addition, the side effects of treatment were similar to those of estrogen therapy. [5,6,7] In one study, patients who showed the most response to PC-SPES were also those who were the most responsive to DES. Reviewed in [8,9] The same study also attempted to find out whether DES or similar compounds were present in PC-SPES. Transcriptional activation assays in yeast strain PL3 Saccharomyces cerevisiae using an ethanolic extract of PC-SPES showed estrogenic activity similar to 1nM estradiol. In addition, ovariectomized CD-1 mice showed substantially increased uterine weights. HPLC, gas chromatography, and mass spectrometry did not reveal the presence of DES but rather that of a compound with similar chemical characteristics. The authors of the report concluded that PC-SPES contains estrogenic compounds that are distinct from DES or other synthetic estrogens.[9]

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