Step into a Japanese restaurant and the odds are you will be offered a cup of green tea to accompany your meal. More than just a popular drink, green tea contains a compound known as epigallocatechin-3-O-gallate (EGCG), which can be used as a nanocarrier for anticancer drugs.
Administered on their own, many small molecule inhibitor drugs used in cancer treatment cause side effects because they are readily taken up by both healthy and cancer cells. Hence, researchers led by Motoichi Kurisawa, a Principal Research Scientist at A*STAR’s Institute of Bioengineering and Nanotechnology (IBN), decided to encapsulate the anticancer drug sunitinib in EGCG and test if they could improve the efficacy of cancer treatment while reducing the off-target toxicity of sunitinib administered on its own.
The encapsulation process involved chemically linking EGCG to the biologically compatible material poly(ethylene glycol), resulting in PEG-EGCG. The researchers then mixed sunitinib with PEG-EGCG, reporting that the compounds self-assembled into nanocomplexes comprising a sunitinib core and a PEG-EGCG shell. The amount of sunitinib within the core, and the size of the nanocomplexes, could be varied by controlling the temperature of the self-assembly reaction.
“We proceeded to evaluate the efficacy of nanocomplexes using appropriate mice models for liver cancer, breast cancer and kidney cancer,” said Kurisawa.
For example, testing their nanocomplexes in mouse models of kidney cancer, the researchers showed that the treatment effectively inhibited cancer cell proliferation, induced cancer cell death and blocked blood vessel formation in tumors. The researchers noted that the tumor growth inhibition by their nanocomplexes was significantly higher (75.4%) than sunitinib administered on its own (0.9%).
Furthermore, the nanocomplexes accumulated more readily in the tumors compared to other organs. Hence, 21.3-fold lower doses of sunitinib (encapsulated in the nanocomplexes) were required to achieve anticancer effects, and this corresponded with fewer toxicity symptoms. According to Kurisawa, the findings from this study lay the foundation for developing safer and more effective drug delivery complexes to improve cancer treatment.
“We are interested in evaluating our nanocomplex in large animals and in humans. Moving forward, we hope to develop our green tea-based nanocomplexes for commercialization,” he concluded.
The A*STAR-affiliated researchers contributing to this research are from the Institute of Bioengineering and Nanotechnology (IBN).
