The Australian Nuclear Science and Technology Organisation (Ansto) said a new radioactive variation of the element scandium, scandium-47, had been produced in the OPAL reactor.
Scandium-47 has the potential to be used as both a therapeutic drug and diagnostic agent.
It was produced for the first time in Australia by Ansto's Biosciences radioisotope development team, which include Paul Pellegrini, Leena Hogan and Attila Stopic, supported by Mike Izard and Ivan Greguric.
Scandium-47 has similar properties to lutetium-177, which is already being used in clinical trials, but with some key advantages.
“Scandium-47 is a beta-emitting radioisotope useful for targeted cancer therapy. However, unlike lutetium-177, scandium has the potential to be a true theranostic agent,” said Pellegrini.
“The decay emissions of scandium-47 are amenable to both targeted cancer therapy and higher quality SPECT imaging than can be achieved using lutetium-177. In addition the PET imaging radioisotopes scandium-43 and scandium-44 can be produced using a cyclotron,” he added.
Ansto said that the theranostic approach typically involves diagnosis and therapy using the chemically similar radioisotopes gallium-68 and lutetium-177, respectively.
Hogan said that while gallium and lutetium are similar, the chemical differences between the metals means "we cannot guarantee equivalent behaviour in the body."
However, using scandium-based radiopharmaceuticals for both diagnosis and therapy achieves this goal.
"Whether you are talking about scandium-44 for PET imaging or scandium-47 for therapy, the agents are chemically identical. This permits clinicians to better estimate a patient’s dose and allows them to safely maximise the administration of the radiotherapeutic agent,” he added.
Pellegrini added that the advantage of radio-scandium is “that it works very well with the macrocyclic molecules currently employed for gallium-68 and lutetium-177”. In fact, scandium has demonstrated better binding stability. “This means that a higher amount of the radioisotope will stay incorporated in the radiopharmaceutical, leading to better clinical outcomes,” he said.
Scandium can also be easily substituted into existing molecular targeting agents for neuroendocrine tumours or prostate cancers, where the theranostic method has already shown great success.
“In the first step, a calcium carbonate target is irradiated in the OPAL multipurpose reactor to yield calcium-47 which decays to the desired radioisotope scandium-47. A chemical separation process is then undertaken and the scandium-47 is isolated for radiotracer and radiopharmaceutical research,” said Stopic.
The team is now focused on scaling up production of scandium-47 and developing methods for other therapeutic radioisotopes.