ReviewPC-SPES: herbal formulation for prostate cancer∗ ☆,
Section snippets
In the beginning
The PC-SPES blend is the result of work by Sophie Chen, Ph.D., a Taiwanese-born, American-educated chemist with a background in the U.S. pharmaceutical industry, and her colleague Xuhui Wang, a Chinese physician (M.D.) with expertise in herbal medicine. The two began working together in 1987, their goal to combine Chinese herbal medicine with Western science. According to an article in the Wall Street Journal, Dr. Wang’s great-grandfather developed a rudimentary version of PC-SPES as a court
Clinical efficacy
Recent studies evaluating the clinical activity of PC-SPES have demonstrated that the initial in vitro observations of biologic activity translate into clinical antitumor effects and toxicities.1, 2, 12, 13
PC-SPES: more than estrogen?
The clinical effect of PC-SPES appears to exceed androgen ablation alone, but is not necessarily independent of an estrogen effect. By comparison, the effects of oral diethylstilbestrol (DES) in patients with androgen-independent disease were studied by Smith and colleagues.16 Twenty-one patients with progressive CaP despite surgical castration or luteinizing hormone-releasing hormone analog therapy were treated with 1 mg DES daily. Nine of 21 patients had a greater than 50% decrease in PSA.
Side effects and toxicity profile
PC-SPES has been associated with a variable incidence of breast tenderness or enlargement and a reduction in circulating testosterone levels (Table III). The occurrence of gynecomastia was reported to be universal in 8 patients by DiPaola et al.1 However, Pfeifer et al.13 reported breast tenderness in only 8 of 16 men. Men in China receiving PC-SPES are said not to experience breast tenderness (S. Chen, personal communication). In three recent studies of 23, 69, and 70 men,2, 12, 14 8.7%,
Mechanisms of action
PC-SPES was originally designed to deliver components with cytotoxic activity toward CaP cells, as well as provide an immunomodulatory function.6 Biochemical and clinical studies have indicated that the PC-SPES effects are mediated at least in part through estrogenic activity,1 but the complexity of the herbal preparation, comprising perhaps hundreds of distinct compounds, suggests that other pathways may also be operative. The clinical data raise the possibility that the responses observed
Appropriate clinical use
The clinical use of PC-SPES at this time appears most appropriate in men in whom conventional androgen-deprivation treatment has failed. Untested future applications might include its use in an adjuvant or neoadjuvant setting, in combination with other treatments, or to make intermittent treatment strategies more effective. In the absence of pharmacokinetic data, the dosing might reasonably begin at 3 or 6 capsules daily, depending on the disease status, and advancing as needed, depending on
Acknowledgements
To Howard Soule, Ph.D., Chief Science Officer of CapCURE, who encouraged this review and provided critical evaluation of the manuscript.
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2008, UrologyCitation Excerpt :In both of our present cases, Prostasol therapy appears to have resulted in a reduction of testosterone levels to the range observed in patients taking GnRH analogs, likely through a hypothalamic-pituitary feedback mechanism.6-8 PC-SPES, an herbal mixture previously studied in clinical trials as a possible treatment of prostate cancer, contained phytoestrogens that were thought to be responsible for the gynecomastia and venous thrombosis seen in patients taking it.6,9,10 PC-SPES was removed from the market in 2002, after it was shown to contain contaminants, including diethylstilbestrol.11,12
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We gratefully acknowledge the help of CapCURE, which provided grant support for much of the research presented herein.
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Editor’s Note: Subsequent to the submission and review of this article, the specific product described (PC-SPES) is no longer commercially available.
- 1
Dr. Chen was an initial co-holder of the U.S. patent for PC-SPES (U.S. patent 5,665,393 issued September 9, 1997); royalty fees were paid to her laboratory (NovaSpes Research Lab) by the manufacturer (BotanicLab, Brea, California) until December 31, 2001, when ownership of the patent was transferred to a charitable trust. She remains a stockholder in the company. Dr. Leaders has formerly been a paid consultant for BotanicLab. None of the other authors has any financial involvement with the manufacturer or the product.
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Deceased.