Roughly half of all cancer patients receive radiotherapy resulting in $5.8 billion spent on such treatments per year. However, the average 5-year survival rates are still too low for many cancers. The high doses of radiotherapy often needed to destroy a tumor can cause significant localized damage to nearby healthy tissue. The use of an adjuvant that increases radiation absorption selectively in tumors could allow lower doses of radiotherapy to have a good therapeutic effect with less harm to healthy tissue.
Gold strongly enhances the absorption of radiation. In the past, gold nanoparticles have been developed that specifically target tumors, enhance radiation absorption, and have an excellent therapeutic effect. However, these gold nanoparticles are large and cannot be excreted, leading to accumulation of gold in sensitive organs such as the kidneys and to potential long-term toxicity. Small gold nanoparticles that are easily excreted do not accumulate in the tumor long enough for a good therapeutic effect. PolyAurum utilizes the best of both and encapsulates small gold nanoparticles in a biodegradable polymer, allowing enough gold to accumulate in the tumor for a good therapeutic effect, but also allowing easy excretion in the urine as the polymer degrades. PolyAurum’s BGNPs can also be used as contrast agents for diagnostic imaging techniques such as computed tomography or photoacoustics.