A WEED extract that has already shown promise as a treatment for skin cancer might also help treat one kind of leukaemia.
The weed is petty spurge (Euphorbia peplus), which has long been used to treat warts and corns. An extract of petty spurge, ingenol 3-angelate or PEP005, developed in Australia by the Brisbane-based company Peplin, produced impressive results when applied directly to skin cancers in animals. Initial human trials of the compound as a treatment for non-melanoma skin cancers, the most common form of cancer worldwide, are under way.
Lab tests had hinted that PEP005 might also be effective against leukaemia cells, so a team at the University of Birmingham in the UK decided to test it against cancer cells taken from eight patients with acute myeloid leukaemia, a particularly aggressive, difficult-to-treat cancer of bone marrow stem cells. It worked in seven of the eight samples, killing between 56 and 95 per cent of the cancer cells at concentrations of up to a hundredth of those that damage healthy cells (Blood, DOI: 10.1182/blood-2004-10-4117) 鈥淭hat鈥檚 a spectacular result for a drug on its own,鈥� says team member Chris Bunce.
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New treatments for acute myeloid leukaemia are urgently needed. On average, people diagnosed with the cancer live only six months, although around 10 per cent respond well to the drug ATRA, with many surviving more than five years. 鈥淲e plan to do a proof-of-concept study in acute myeloid leukaemia patients in early 2006,鈥� says Peter Welburn, director of drug development at Peplin.
PEP005 activates an enzyme called protein kinase C, the target of several new experimental anti-cancer agents. The drug kills leukaemia cells by triggering controlled cell suicide, in which cells dispose of themselves in a tidy manner, breaking down enzymes that might damage neighbouring cells. In skin cancers it works in a different way, killing the cancer cells by triggering necrosis, in which cells burst open and release their contents. This can damage neighbouring cells and trigger an inflammatory response, a potential advantage when treating a localised cancer.
