OXFORD, U.K.—An anti-malaria drug could help radiotherapy destroy tumors, according to a Cancer Research UK-funded study published in Nature Communications recently. The study, carried out at the Cancer Research UK Radiation Research Centre in Oxford, looked at the effect of the drug, called atovaquone, on tumors with low oxygen levels in mice to see if it could be repurposed to treat cancer.
As Cancer Research UK explains the rationale behind this effort, radiotherapy works by damaging the DNA in cells. However, a good supply of oxygen reduces the ability of cancer cells to repair broken DNA. So when a tumor has low levels of oxygen, it can repair itself more easily after radiotherapy.
This means that tumors with low oxygen levels are more difficult to treat successfully with radiotherapy. They are also more likely to spread to other parts of the body. The recently published research showed for the first time, Cancer Research UK said, that an anti-malaria drug slows down the rate at which cancer cells use oxygen by targeting the mitochondria, the powerhouses of the cell that make energy, a process that uses oxygen.
By slowing down the use of oxygen, this drug reverses the low-oxygen levels in nearly all of the tumors. The fully oxygenated tumors are then more easily destroyed by radiotherapy.
The drug reportedly was shown to be effective in a wide range of cancers, including lung, bowel, brain and head and neck cancer. This older medicine is no longer patented and is readily and cheaply available from generic medicines manufacturers.
“This is an exciting result. We have now started a clinical trial in Oxford to see if we can show the same results in cancer patients,” said lead author Prof. Gillies McKenna at the Cancer Research UK/Medical Research Council Institute for Radiation Oncology in Oxford. “We hope that this existing low-cost drug will mean that resistant tumors can be re-sensitized to radiotherapy. And we’re using a drug that we already know is safe.”
Dr. Emma Smith, Cancer Research UK’s science information manager, added: “The types of cancer that tend to have oxygen-deprived regions are often more difficult to treat, such as lung, bowel, brain and head and neck cancer. Looking at the cancer-fighting properties of existing medicines is a very important area of research where medical charities can make a big impact and is a priority for Cancer Research UK. Clinical trials will tell us whether this drug could help improve treatment options for patients with these types of tumor.”