PC SPES, Herbal Compound, Lowers PSA in Men With Advanced Prostate Cancer, UCSF Study Finds

UPDATE FEB 2 2001: PC SPES Trial Closed, Prostate Cancer Herbal Product Contains DES

October 28, 2000 -- A mixture of herbs popular with some prostate cancer patients has been found to significantly reduce prostate specific antigen (PSA) levels -- a protein in the blood that often indicates prostate cancer -- in men with advanced disease, according to a University of California, San Francisco study.

The study, one of a series in the past two or three years to subject the PC-SPES mixture to scientific scrutiny, will be published November 1 in the Journal of Clinical Oncology.

The PC- SPES formula comes from Taiwan, named by herbalists to appeal to Westerners -- "PC" for prostate cancer; "SPES," Latin for hope. The formula consists of extracts from eight Chinese herbs. PC SPES is sold at some health food stores, by phone and mail order and over the Internet.

"My belief is people approach complementary medicine in two ways. They either accept it without critical thought simply because it's alternative, or they reject it without critical thought because it's alternative," said Eric Small, MD, study lead author and UCSF associate clinical professor of medicine. "Either way, it's all opinion. We wanted to study PC-SPES and hold it to the same standard as we would any other new drug." This trial, he said, is an attempt "to study this herb in a scientifically methodical way."

Testosterone, the male hormone, fuels prostate cancer growth. Lowering testosterone levels can cause tumors to shrink or slow their growth. As a result, PSA levels fall. So long as tumors remain hormone dependent, they respond to withdrawal or blockade of the male hormone testosterone. This is done by means of various drugs that affect hormones, from Lupron or Zoladex and Casodex to the female hormone, estrogen. Estrogen, used as an alternative or adjunct to surgical castration (orchiectomy) in the post-world-war II period, has been abandoned generally because of its tendency to cause blood clots.

Prostate cancer tumors can eventually become resistant, or refractory, to hormonal therapy. Hormone independent disease is defined by cancer progression despite low testosterone levels. Among patients with advanced prostate cancer there is a great deal of interest in whether PC SPES can help men with hormone independent disease.

The phase II study of PC SPES evaluated 70 men divided into two groups: those with hormone dependent disease (33 patients) and those with hormone independent disease (37 patients).

All of the men in the hormone dependent arm of the study had a PSA drop of greater than 80 percent, with a median duration of that decline lasting 57 or more weeks. Only one patient had disease progression while taking the herb. About 97 percent of these patients had steep declines in their testosterone also, an indication that PC-SPES may work like standard hormonal therapy, Small said. "We think PC-SPES is estrogen-like," he said.

In the men with hormone independent disease, 19 men, or about 50 percent, had PSA declines of greater than 50 percent. Median time before PSA increased was 16 weeks. But several men in this group have not had any disease progression in more than a year of taking the herb.

The finding that PC-SPES can lower PSA levels in men with hormone independent disease is significant, Small said, because it represents another line of defense for patients when standard hormonal therapy fails to slow the disease.

"In this group of patients we can use another hormone, but beyond that, short of chemotherapy, there is not much more we can do," Small said. "PC-SPES can be used as a second or third line hormone. We don't know what kind of impact it will have on survival, but it clearly offers a clinical benefit. It provides us with another treatment we can use before chemotherapy."

In addition, some men in both groups saw shrinkage of their tumors. Side effects included impotency, lowered sex drive and breast tenderness. Overall, PC-SPES was well tolerated. The men were enrolled in the trial for two years and were given a dose of nine capsules daily.

While PC-SPES appears to be mimicking estrogen in men with hormone dependent disease, Small and colleagues believe there may be other active anti-cancer ingredients in the supplement because it lowered PSA levels in men with hormone independent disease whose testosterone was already low.

"We have proven that this has some activity," Small said. "The next step is to sort out if this is any different from estrogen," he said.

To that end, Small and colleagues at Dana Farber Cancer Institute in Boston, MA are enrolling 100 men with hormone independent disease for a trial to test which agent, estrogen or PC-SPES, works better to slow the disease. Once one therapy stops producing PSA declines, the patient will be switched to the other agent. Patients will be enrolled for a year.

"The importance of that study is it will help us get to the mechanism of PC-SPES," Small said.

Typical side effects of PC SPES, according to UCSF, are:

• Nipple tenderness
• breast enlargement
• loss of libido (decrease in desire to have sex)
• decrease in erections (in men not previously on testosterone-blocking therapy)
• "Frequent loose bowel movements or diarrhea -- usually mild, in about 1/3 of patients"
• Leg cramps or muscle cramps -- about 1/3 of patients
• Changes in urine flow
• Fatigue
• Blood clots in legs or lungs
• Allergic reactions. "A few patients have developed either face swelling, tongue swelling, difficulty swallowing, or possibly difficulty with breathing. In most cases, we think this is probably an allergic reaction to PC-SPES. There is nothing special that you need to do except to be aware of this, and should you develop any of these symptoms, please make sure that you get to an emergency room immediately. We would also recommend that you carry Benadryl (25 mg) with you at all times."

Other authors on the paper include Mark Frohlich, MD, UCSF assistant professor of medicine; Robert Bok, MD, PhD, UCSF assistant clinical professor of medicine; Katsuto Shinohara, MD, UCSF assistant professor of urology; Gary Grossfeld, MD, UCSF assistant professor of urology; Zinovi Rozenblat, UCSF clinical research associate; William Kevin Kelly, DO, Memorial Sloan-Kettering Cancer Center; Michele Corry, NP, UCSF; David Reese, MD, UCSF assistant clinical professor of medicine.

The study was supported by the Association for the Cure of Cancer of the Prostate (CaP CURE).
edited by J. Strax at PSA Rising.

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UCSF PC SPES "Medical Care & Info" page for patients on study.

PC-SPES Effects on Patients With Androgen Dependent Prostate Cancer Fox-Chase March 1, 2000.

PC-SPES UPDATE: Early Results of UCSF Phase II TriaL: Herbal Therapy Lowers PSA in Men With Advanced Prostate Cancer, Study Shows May 6-July 9, 1999

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