A new treatment, which could significantly improve outcomes for men with locally advanced prostate cancer, has been developed by researchers at Queen’s University Belfast.

The new treatment is used in combination with radiotherapy, which is already extensively used to treat a range of localised cancers, including prostate cancer. However, radiotherapy fails to work in almost one-third of prostate cancer patients.

The treatment can make cancerous cells up to 30% more receptive to radiotherapy, while simultaneously reducing adverse side-effects that can affect quality of life.

The researchers have developed a new nanomedicine comprised of tiny gold particles, coated in a small peptide called RALA. If these nanoparticles are present in tumour cells when treated with radiotherapy, they increase the cell-killing potential of this conventional treatment, helping to reduce the risk of disease relapse.

In the absence of radiation, the gold nanoparticles are not directly toxic, meaning that the risk of treatment-related toxicity is low.

While various researchers worldwide have reported that gold nanoparticles, or other high-atomic number elements, hold the potential to sensitise tumour cells to radiation treatment, one key challenge has been delivering these particles in sufficient levels to the right regions within the tumour cells.

Combining the gold particles with RALA increases the efficiency of nanoparticle uptake, while also enabling the gold particles to be delivered to regions within the cells that are more sensitive to the effects of radiation damage. 

The researchers found that with this new formulation, prostate cancer cells were rendered up to 30% more sensitive to the cell-killing effects of the same radiotherapy used to treat patients.

Furthermore, in experiments investigating the magnitude of effect in small three dimensional models of prostate tumors called tumourspheres, the combination of radiation and RALA-gold nanoparticles completely suppressed tumoursphere growth.

“The peptide enables the gold nanoparticles to be delivered more efficiently to the tumour cells. The gold then interacts with the radiotherapy, increasing the cell-killing effect in a highly localised manner,” explained Prof Helen McCarthy of Queen’s University Belfast.

The researchers noted that the gold particles are up to three times more visible on standard medical imaging equipment. This means that if the nanoparticles are located within the tumour, they should help to improve the accuracy of radiotherapy delivery, reducing the risk of off-target damage to neighboring normal tissue, such as the bladder or bowel. 

“Our research has shown that ultra-low concentrations of the RALA-gold nanoparticles effectively sensitise prostate tumour cells to radiotherapy. Now we want to build on this work to address the second major challenge - consistently delivering sufficient nanoparticles to the tumour throughout a patients’ radiotherapy,” said Dr Jonathan Coulter of Queen’s University Belfast.

The researchers are proposing to develop a biodegradable implant designed to provide sustained release of the gold nanoparticles.

“Following insertion into the main tumour lesion, the biodegradable implant will consistently release the nanoparticles over time. This is opposed to current approaches that involve daily injections. Following consultation with a local prostate cancer patient focus group, we learned that a one off implant would be better tolerated by patients than regular injections to the tumour,” Dr Coulter explained.

Details of this research are published in the Journal of Nanobiotechnology and can be viewed here.