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How our researchers are using gold to ‘super charge’ cancer therapies

New data published  by Dr Flavio Curnis  and his colleagues in Milan show that tiny gold particles could potentially boost the effectiveness of their prototype cancer therapy even more. This is brilliant news. But why did they use gold? And isn’t it a bit expensive to start adding to medicines (as well as medals)?

So what’s nanomedicine, and why gold?

In cancer, nanomedicine researchers try to find ways to exploit the properties of very, very, small particles to help improve treatment and diagnosis of tumours. These tiny particles can be made of just about anything, from fat, to carbon, to metals, all with different characteristics, and all with different behaviours in the body. The researchers select the type of particle they want to develop, depending on what they want it to do.

Several reasons make gold an especially attractive option for use in new nanomedicines. Perhaps most importantly, it seems to do practically nothing. The ability to ‘do nothing’ might be not exactly what you expect for a cutting-edge new cancer therapy, but the impressively unreactive nature of gold compared to other substances actually makes it a great material for using relatively safely in the body, with minimal risk of unwanted reactions.

Gold particles are also pretty easy to manipulate in size and shape, they can easily be chemically altered to attach to drugs or other nanomaterials, and have special properties which can make them especially good to see in the body using scans and other imaging techniques.

These characteristics coupled with recent biotechnological progress have fuelled a boom in gold-based nanotechnology research. A 2012 study found that the number of gold nanoparticle research papers has mushroomed over the last 20 years, from practically none in 1995 to around 5000 in 2009. That’s a lot of research- and it’s now starting to bear fruit for patients.

Gold as a drug carrier

Much hullaballoo currently surrounds the use of gold-based particles as ‘carriers’ of new cancer drugs and therapeutics, meaning the gold particle is attached to a drug to improve its targeting to the tumour. This is how Dr Curnis and his team used nanogold particles in their recent study. But how does gold help target drugs to tumours?

The idea goes like this. Tumour blood vessels tend to be ‘leaky’, with large holes in their walls which gold particles can fit through. Any gold particles in the blood stream will therefore easily escape through these holes and collect in and around the tumour. More gold-attached drug at the tumour site means more drug available to attack the tumour, and less drug wreaking havoc elsewhere in the body. If more drug is getting to the tumour then it also means less drug is needed overall, and smaller doses mean fewer side-effects. It’s an exciting idea and the first ever gold-particle based drug therapy to treat cancer reached early-stage clinical trials  in 2005, with more clinical trials currently underway.

Gold for light and heat therapies

This tendency for nanogold particles to accumulate in and around tumours also makes them an attractive option for improving the accuracy of cancer therapies which use heat and light energy to destroy cancer cells, such as the laser-based photodynamic therapy Worldwide Cancer Research funding helped to develop a few years ago.

Photodynamic therapies have promise, but they are still limited in their use against cancer. This is because they can also damage healthy tissue surrounding the tumour, and cannot be used for tumours deep within the body. Researchers think gold nanoparticles will help to ‘soak up’ and focus the energy on the tumour cells, with minimal damage to the surrounding healthy cells. Tiny gold particles in the shape of rods, spheres, and even cages and lattices are all being investigated for their ability to enhance heat, light, radiation and drug-based therapies. One of the first clinical trials of its sort using infra-red laser activation of gold shell-shaped nanoparticles to treat lung cancer is currently underway in the US, with expected completion soon.

Gold in cancer diagnosis and monitoring

The special characteristics of gold, along with its penchant for gathering around tumour blood vessels when injected into the body, make it a potentially a very handy ‘contrast agent’ for picking out tiny tumours during diagnostic scans , or highlighting particular features of larger tumours during treatment.

Researchers are currently investigating how best to exploit gold for cancer diagnostics and monitoring not just using scans and imaging, but in a number of different ways- including how gold nanoparticles could help detect cancer in the blood, or even on a person’s breath .

So what now?

Watch this space. As more and more clinical trials investigating the uses of gold in nanomedicine get underway, expect to hear a lot more about it in the news in the coming years. ‘Second generation’ nanomedicines such as the one developed by the Dr Curnis and the team in Milan, which combine gold particles with other forms of nanotechnology and therapies are already on the horizon.

But there’s still one more question to answer- isn’t gold a bit too expensive to be adding to cancer medicines? If it helps save patients’ lives, then it’s well worth the cost. And anyway, a quick internet search reveals you can buy 80 mg of gold nanoparticles online for just $372  (that’s roughly £260).

Gold nanoparticle medal anyone?

Other nanomedicine projects funded by Worldwide Cancer Research

Read how Dr Paola Allavena in Italy is finding ways to combine chemotherapy, immunotherapy and nanotechnology to treat cancer.

Read about Dr Maria Soengas’s project in Spain, and how she is disrupting melanoma skin cancer cells with nanoparticles.

Read how Dr Khuloud Al-Jamal in London is using nanocapsules to improve the efficiency of radiotherapy.

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