Gold nanoparticle cancer treatment in dogs has no observed side effects

We have witnessed the devastating side effects of current cancer therapies for far too many years -- we might be able to shrink or destroy cancerous masses or cells, but the effects of blasting an individual with localised radiation or injecting toxic chemicals into their bloodstream are, in themselves, deadly. We're due to wait until till as long as 2030 to see graphene become a drug delivery tool that targets only cancerous cells, but now, a collaborative team at the University of Missouri has proven that radioactive gold nanoparticles are an effective and side effect-free cancer treatment -- at least, that is, in dogs with aggressive prostate cancer.

"Dogs represent such a good model because they develop the disease naturally," explains Sandra Axiak-Bechtel, an assistant professor of oncology at the University of Missouri (MU) College of Veterinary Medicine. "It's a disease that normally we don't have a particularly good treatment for so it offers us as veterinarians the opportunity to better and more aggressively treat the disease while preserving their quality of life, and in the future hopefully it will give us a better way of treating men with prostate cancer more aggressively as well."

Previous research by Stanford University had revealed the potential for gold nanoparticles to "tag" cancerous cells. The nanoparticles were coated in imaging reagents before being introduced to brain tumour patients. "We hypothesised that these particles, injected intravenously, would preferentially home in on tumours but not healthy brain tissue," said lead radiologist on the case Sam Gambhir. This, he added, is down to the fact that, "the tiny blood vessels that feed a brain tumour are leaky, so we hoped that the spheres would bleed out of these vessels and lodge in nearby tumour material." They did just that. Using MRI, photoacoustic and Raman imaging, the coated particles could be picked out and act as a map of the brain tumours. All that was left to do was activate the gold nanoparticles so that they could go from passive mapping tools to weapons.

And this is exactly what the MU team has done.

The treatment involves introducing radioactive gold nanoparticles directly to a prostate tumour, causing it to shrink. Thus far, it has produced no side effects in the dogs taking part and has also been successful in shrinking tumours in mice. The doses required are thousands of times smaller than those used in chemotherapy, and it can also be introduced directly to the tumour, rather than passing into disease-free tissue and organs.

The results are a huge step forward in the advancement of nanotechnology in healing and curing cancer. Until now, therapy using gold nanoparticles to attack cancer cells has been purely lab-based. For instance, pancreatic cancer cells have already been destroyed using gold nanoparticles shattered by radiowaves, and breast cancer cells were destroyed in experiments using a targeted 42C laser. How safe these procedures would be in human subjects still remains to be seen, but the side effect-free dogs -- the only other mammal to naturally develop prostate cancer -- sets an exciting precedent.

According to Cancer Research UK, prostate cancer is the fourth most common form of the disease in this country, with 40,841 new cases in 2009. If it is not picked up at its early stages, it becomes very aggressive and spreads rapidly. At that point, high doses of chemotherapy are the main course of treatment but are largely ineffectual in delivering a cure. It's another reason why dogs were the ideal candidates for the study. Not only is it naturally occurring in them, suggesting the results would also be mirrored in humans, says Axiak-Bechtel, but it usually goes undiagnosed for too long: "Because dogs can't tell us how they feel, many times they are diagnosed with the disease too late, but this treatment gives us some hope that we can still combat aggressive tumours".

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Gold nanoparticle cancer treatment in dogs has no observed side effects