PC-SPES - 'hopeless' case or timely warning?

Just under two weeks ago, a study​ was published in the prestigious Journal of the National Cancer Institute​ which confirmed that a widely used 'natural' treatment for prostate cancer was in fact contaminated with synthetic drugs.

The dietary supplement PC-SPES ('PC' for prostate cancer, and 'spes', the Latin word for hope) is a mixture of seven medicinal herbs and saw palmetto but researchers in California seeking to identify its successful components discovered that the compound contained warfarin, diethylstilbestrol and indomethacin. Both diethylstilbestrol and indomethacin have known anti-cancer properties.

One of the study leaders, Professor Milos Sovak of the Medical School at University of California, San Diego​, told NutraIngredients.com that while the results of his research came as a blow, they merely emphasised the need for 'this kind of policing work' in the booming nutritional supplements industry.

"There are people who were obviously harmed by PC-SPES, either by its lack of efficacy or side-effects from the synthetic components of the supplement. And if the consumer loses confidence in supplements and becomes more vigilant, well, this is why we wrote the article."​

Since publication of the research, the researchers have been inundated with responses, most complimentary. The evidence is likely to lead to lawsuits but Sovak also hopes supplement producers will immediately put safeguards in place.

"This should be the responsibility of every producer and marketer in the industry. I don't think we want to see the government stepping in - the obligation rests with the producers. And whether it is the FDA or European lawmakers, both have almost identical legislation which requires the producer to stand scientifically and legally behind its product."​

For Sovak, the issue of safety and efficacy is of fundamental importance to the industry as a whole.

"It is absolutely unavoidable that we should have laws for standardisation. If any of these products are going to be used with a degree of reasonable safety and efficacy, they have to be standardised and produced under strict GMP conditions. If manufacturers abide by GMP rules, they have passed all the tests."​

He added: "Maybe it is up to the public to decide for itself whether a supplement is effective, but no-one has the practical means of assessing safety apart from the producers. We should hold them responsible - after all, they are the ones making money from this."​

There is, however, some doubt about the abilities, both financial and scientific, of many manufacturers to carry out the safety tests required.

"Companies have to invest in labs, know where their raw materials come from, certify their products and carry everything out under GMP - the crucial documentation. I think it is 'do-able', but don't forget that large pharmaceutical companies [with the means to produce nutraceuticals] don't want to get involved as many natural substances can't be patented."​

This is not the first time science has called the bluff of herbal supplements. Only recently a Chinese company was caught selling herbal extracts contaminated with steroids to treat skin conditions. It begs the question - how does the public still have so much faith in herbal supplements when they often make completely unfounded claims? Perhaps the debate needs to be linked to the wider picture.

"There is a certain loss of confidence in the medical system in recent times. Whether people have problems paying for it, as in the US, or whether they are theoretically entitled to medical care yet don't receive it for various reasons, as in Europe, the public is looking for alternatives,"​ claimed Sovak.

"And the public is becoming aware that about half of all pharmacopoeias are originally derived from plants so there is this return to traditional supplements. But these have to stand up to reasonable scientific scrutiny."​

The loss of confidence can also be blamed in part on the pharmaceutical industry, maintained Sovak. There is an increasing sense that the industry is not out for the best interests of the public. But can the small, new nutraceutical companies compete in a market which is seeing increasing consolidation? Sovak has his doubts.

"I am not sure if safe natural supplements can be developed by companies who are not powered by profit. Nutraceutical companies not only lack financial means but also the mechanisms to set the development process in motion."​

He sees one logical, but perhaps far-off, solution - the possibility of orphan drugs, like the system established by the pharmaceutical industry to encourage production of medicines seen as unprofitable. Orphan drugs based on nutraceutical extracts would allow for a return of profit not often seen in the current supplement market. Until this happens, however, supplement manufacturers face a continuing battle to establish the safety and efficacy of products which remain in the grey area between food and drug legislation.

"I am not sure where this issue can go. But the answer should not be the typical European one, to opt for ever-tighter regulation. That will be the kiss of death for the industry,"​ argued Sovak.

Meanwhile, the recent study has had some positive results. "I set out to identify in a solid scientific way the active agents in this compound and finding that they were, in all likelihood, synthetic drugs was 'innocence lost',"​ said Sovak, who had observed very encouraging results in patients taking the supplement.

"However, I would not exclude the possibility that there may be some synergy between the herbal extracts and the synthetic drugs. This is what we are currently studying."​

Sovak and colleagues are continuing their research on the effects of substances derived from PC-SPES and other natural compounds on prostate cancer cells. There is also a project underway to test a paclitaxel derivative. And as in many clinical trials, there have been some unexpected outcomes - there is renewed interest in DES (in the synthetic substances found in PC-SPES ) as a much cheaper alternative to current prostate cancer treatments and one which may be safe when used in low dosages.

The case of PC-SPES suggests that the science is the easy part. It is the surrounding political and ethical questions which cause the controversy. Can we rely on producers to stick by the rules or should the government become involved in consumer protection. something which Sovak is clearly against? Whatever the answer, the words of Dr Jeffrey White of the National Cancer Institute, who wrote an accompanying editorial to the study, seem like good advice:"The loss of a product that symbolised hope to some should not occur without leading to an ultimate gain for all cancer patients."​