A possible prostate cancer therapy from a natural product?


A newly published paper in the journal Antioxidants & Redox Signaling suggests the possibility that a natural product known as nimbolide may be effective in the treatment of prostate cancer.

Now, it would be nice to think that such naturally derived products would be both effective and very safe in the treatment of prostate cancer (or other forms of cancer too). Drugs have often been derived from all sorts of natural products in the past, but — in truth — few of them are as safe as one might really want them to be (although they can be extremely effective — several antibiotics are particular cases in point; docetaxel or Taxotere is also a naturally derived product, from the bark of yew trees).

The paper by Jingwen et al. (also discussed in a commentary on the ScienceDaily web site which may be rather easier to follow) addresses the derivation of nimbolide from a medicinal plant called the neem plant (Azadirachta indica, a member of the mahogany tree family) that is native to India and the Indian sub-continent. Neem has been a component of traditional Asian medicine for centuries and is typically used in Indian Ayurvedic medicine. Neem leaves and bark and their extracts are commonly used in the manufacture of many Asian personal care products, including soaps, toothpaste, skin care products and some dietary supplements.

However, what the authors have done is extract nimbolide from the neem plant and then test its activity in cell lines and in laboratory mice. This means that they may have used doses of the nimbolide that could not be converted into safe dose levels in humans. In addition, we have no idea whether nimbolide given to mice in this manner would exhibit similar effects in humans. Indeed, the vast majority of products that have ever shown activity against prostate cancer in cell lines and mouse models have never been able to demonstrate the same effects in humans with prostate cancer.

In writing this commentary up, we do not in tend to be negative about this opportunity, but we do intend to be realistic. If nimbolide is to become a useful drug for the treatment of prostate cancer, it will need to go through the same standard set of processes as any other product, including:

  • The type of careful pre-clinical testing described by Jingwen et al.
  • Phase I clinical trials to establish what the appropriate dose level might be to give safely to men with prostate cancer
  • Phase II studies to confirm that the drug has appropriate activity and is actually safe in a small to medium-sized group of patients
  • Phase III clinical trials to actually prove that the drug is as good as or better than the current standard of care with an appropriate level of safety

About 1 in 5,000 drugs of any type make it through this rigorous process … and the fact that they are derived from natural products actually has very little impact on the likelihood that they may do so. So …

Jingwen et al. have described a possible new agent that may be worth testing in man as a candidate for the treatment of prostate cancer … and that’s a good thing. Whether nimbolide can actually be shown to be as (or more) effective and safe than other products already available to us is going to take a lot more time to establish … and a lot of money would need to be invested to demonstrate this.

Last but not least, anyone who is going to make such a financial investment will need to be sure that they can gain appropriate patents on nimbolide (or some derivative thereof) as a drug for the treatment of prostate cancer. That may come with some other challenges.

5 Responses

  1. You’ve got it the wrong way round. Mice are actually running complex experiments on us. This was clearly explained in The Hitchhiker’s Guide to the Galaxy.

  2. Indeed … and of course this may well be true, like everything else documented in such detail by the estimable and highly respectable Mr. Adam’s.

    How Wikipedia can describe HG2G as “comedy science fiction” is utterly beyond me! Furthermore, I am proud to be able to inform you that in 1978 I listened to every single episode of the original on Radio 4 (without any of the distractions of the Internet!).

  3. PubMed lists quite a number of other studies regarding cancer and nimbolide.

  4. Just curious. Obviously, nobody is going to expend funds on these trials unless he can get a patent. But I assume one can’t patent a natural product. So, is it a patent on the process that leads to the product derived from the natural ingredient?

  5. Cliff:

    There are all sorts of things one might be able to get the patent on: the product extraction process; the use of the product for a particular form of treatment; the product refinement and purification process; you name it. I’m no patent expert.

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