Samarium-153, a radioisotope produced by the research reactor at the Australian Nuclear Science and Technology Organisation (ANSTO), is a focus of attention for researchers seeking ways to combat cancers that have spread throughout the body. Because of its ability to deliver gamma rays to cancer cells, scientists are endeavouring to link samarium-153 with agents which seek out tumours, sometimes referred to as a "magic bullets".
Scientists are now trying to discover the best ways to attach these magic bullets to Samarium, so that the radioisotope can destroy the tumours that have been targetted.
With the help of a grant from the Australian Institute of Nuclear Science and Engineering, Professors John Webb and Robin Giles of Murdoch University in Perth are currently working on projects to overcome difficulties in delivering the isotope effectively to the sites in the body where it is required. Already, the team has made significant strides in finding chemical agents to team up with the radioisotope. The Murdoch team has identified two methods for bonding other agents to the samarium-153 and is currently evaluating which is most stable inside living organisms.
Professor Webb said that by delivering radiation to cancer cells only, doctors would be able to apply relatively high doses to tumours without harming healthy cells and causing major side effects in cancer patients. However, there are a number of hurdles that need to be overcome to reach this stage.
"A great deal happens to the samarium in the time that it takes to travel to the tumour from the syringe. Our task is to try and find a way to effectively deliver the gamma rays from the samarium to the tumour, without losing its effectiveness along the way," Professor Webb said.
Samarium is already used in a treatment produced by ANSTO called Quadramet®. With a single injection, Quadramet® can provide up to three or four months of pain relief for people with breast or prostate cancer that has spread to bone.