The study in mice, led by Bernard Gallez, Ph.D., professor of pharmacy at the Université de Louvain in Brussels, Belgium, found that by injecting Botulinum neurotoxin type A into two types of mouse tumors, the tumors' cellular vasculature opened, allowing for more effective destruction of previously resistant cancer cells. The study is the first to test the idea of using Botox against cancer and explores the possibility of its use as an adjuvant, assisting the effective delivery of chemotherapies and radiation.

The findings mark a relatively new area of cancer research, which focuses on briefly opening blood vessels that feed tumor cells in order to better deliver therapeutic agents. Until recently, much cancer research has focused on the opposite: reduction of blood vessel growth, which starves tumor cells of nutrients.

While chemotherapy and radiation treatments have remained the standard of care, tumor cells of most cancer types have shown increasing resistance to therapies. This phenomenon has resulted in more toxic dosages of chemotherapy and radiation, and increased efforts to develop more drugs to which tumors don't show resistance. To increase the efficacy of anti-cancer treatments, the new study examined strategies that transiently opened the tumor vascular bed to alleviate tumor hypoxia.

"Hypoxia is a source of resistance to radiotherapy, and is a determining factor in the poor prognosis of tumors to cytotoxic treatments," said Gallez. "Botulinum toxin could lead to inhibition of contractions of tumor vessels, improve tumor perfusion and oxygenation, and enhance the response of tumors to radio- and chemotherapy."; Source: American Association for Cancer Research