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Rural Industries Research & Development Corporation
Growing Milkweed a plant with prospective anticancer properties: A review of the medicinal potential of members of the Euphorbiaceae family. by Dr Craig Davis and Dr Peter Parsons
January 2002RIRDC Publication No 02/00 RIRDC Project No DAQ-281A
Peplin Biotech has discovered a novel class of natural compounds, purified from Euphorbia, which show great potential in the laboratory as a potent treatment for a wide range of human cancers including breast and prostate cancer, leukaemia, melanoma and other skin cancers, as well as lung, colorectal and cervical cancer.
An early clinical trial on thick and thin non-melanoma skin cancers has confirmed that the compounds are very effective in producing long-term (possibly permanent) responses in human patients without any evident systemic toxicity when applied topically. This is highly significant because current topical methods of drug treatment require long periods of application without being fully effective, and physical methods (e.g. surgery) are expensive and difficult to apply to the large areas affected, especially in older people.
Topical treatment of non-melanoma skin cancer - basal cell carcinomas (BCC) and squamous cell carcinomas (SCC) - will be the first medical application of the E.peplus product. These are the most common human cancers, and most Australians will develop one or more BCC or SCC in their lifetimes. Mortality from melanoma is about 50% in the state of Queensland and morbidity is high.
The treatment of non-melanoma skin cancer costs over $200 million dollars in Australia, making it the most expensive cancer. The rate of increase in skin cancer has slowed, presumably due to education in prevention measures but the incidence continues to be high and may increase with the ageing of the population. Western countries with less UV flux than Australia also have high incidences of non-melanoma skin cancer, due to sun-seeking lifestyles. In the US, the annual cost of non-melanoma skin cancer has been estimated at US$3.5 billion. There is therefore a need for a simple, reliable method of treating skin cancer on a large scale.
Over 70% of current pharmaceuticals are natural products or have been developed from a natural product lead. E.peplus is one of a number of plants in the Euphorbiaceae family that has attracted attention as a home remedy for skin cancer because of its milky sap. However, a survey by Peplin Biotech of over 200 species of the Euphorbiaceae family has shown that only E.peplus has the desired attributes of anti-cancer efficacy in vitro and in vivo. In addition, E.peplus is not a noxious weed, it grows rapidly, produces harvestable seed and it is potentially suitable for large-scale agricultural production. Thought to originate from Europe, E.peplus is now widespread throughout the world and can be found in most gardens.
Methods have been developed by Peplin Biotech for the extraction and purification of compounds from E.peplus in the laboratory, and these are currently being scaled-up for commercial production.
It is anticipated that the overall cost of producing the active ingredient in pure form will result in a commercially viable treatment, provided the cost of agricultural production can be kept low.
The limiting factor in capturing commercial value from these discoveries is therefore the availability of plant feedstock for extraction of the active compounds. Developing large-scale agricultural production can solve this problem. Currently, the plant is sown by hand and tended in plots of 10-100 sq m. Harvesting of seed and plant is also carried out by hand. Sufficient information has now been obtained to show that there is no inherent difficulty in large-scale production in a variety of locations and environments in Australia.
We plan to evaluate methods for complete mechanisation of E.peplus cultivation and sap production.
This will include methods of seed production, since the current supply of seed will need to be greatly expanded. The requirements for large-scale agriculture will be ascertained, using the expertise and equipment pooled from the wide variety of specialists in the DPI. The next critical step is to develop methods suitable for broad-acre, mechanised production.
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