Polyvinyl acetate or 'PVA glue' is often associated with school projects and woodcraft activities. A key ingredient in its production might have a hidden medical superpower in cancer treatment, according to a study led by the University of Tokyo in Japan.
Specifically, adding the compound polyvinyl alcohol to a radiation therapy mixture used to treat head and neck cancers improves targeting of tumor cells, leaving healthy ones with less damage.
"We discovered that [polyvinyl alcohol], which is used in liquid glue, dramatically improves the efficacy of a compound called D-BPA, that until now has been removed from drug ingredients because it was considered useless," says the senior author of the study Takahiro Nomoto, a biomedical engineer from the University of Tokyo.
The cancer treatment boron neutron capture therapy (BNCT) requires patients to receive a drug that loads tumor cells with the element boron, which absorb a delivery of neutrons and decay in a radioactive burst, killing the surrounding cells.
While this precise targeting is effective, the low-energy stream of neutrons can only be deployed into cancers close to the skin surface. How well the boron is retained in the tumor cells also has an impact on its effectiveness.
By adding polyvinyl alcohol, the researchers had previously managed to improve the effectiveness of a critical ingredient in the drug called L-BPA.
However, L-BPA can also enter healthy cells in certain scenarios, leading the researchers to turn their attention to a similar substance called D-BPA.
Unlike L-BPA, D-BPA doesn't accumulate in cancer cells, which is why it hadn't previously been used in cancer treatment. Combined with polyvinyl alcohol, however, D-BPA was shown to be even better than L-BPA at amassing boron in tumors and keeping it in place.
"In a subcutaneous tumor model, this system accomplished surprisingly high tumor-selective accumulation that could not be achieved by conventional approaches and induced drastic BNCT effects," write the researchers in their published paper.
"[Polyvinyl alcohol] may be a unique material to unlock potentials of seemingly inert molecules."
More research needs to be done to prove this works in actual therapy treatments, but the lab tests are promising. If there's more boron inside the cancer cells, and it's sticking around for longer, streams of neutrons should trigger the destruction of cancerous tissue at a faster rate, making for shorter treatments that cause less collateral damage.
"There are many demands in the development of drugs for cancer treatment and much recent research and development has focused on complex combinations of expensive molecules," says Nomoto.
"However, we are concerned that such methods, when put into practice, will be so expensive that only a limited number of patients will benefit. In this study, we aimed to develop a drug with a simple structure and high functionality at a low cost."
The research has been published in the Journal of Controlled Release.