Antidiabetes Drug Makes Lung Cancer Susceptible to Radiotherapy

Metformin, an anitdiabetic drug, has been shown to slow the growth of lung cancer cells and makes them more likely to be killed by radiotherapy.

Scientists from McMaster University (Hamilton, ON, Canada) discovered that metformin acted on the defense mechanisms non-small-cell lung tumors—the most typical form of the disease—use to resist radiotherapy. They published their findings April 30, 2013, in the British Journal of Cancer.

Lung cancer cells typically adapt to radiotherapy by activating survival processes that make them resistant to the treatment and even helps them to grow faster. However, by examining lung cancer cells grown in the lab and in mice, the researchers showed that metformin reverses this effect, once again making them sensitive to radiotherapy. Significantly, the researchers utilized “real life” levels of the drug in their experiments, similar to those already used for treating diabetes.

Metformin seems to work by enhancing the damage-detection signals sent within cancer cells in response to radiotherapy, over-riding the cells’ survival mechanisms. These signals blocks cancer cells from producing the new proteins they need to grow rapidly, prevents them from making new cells and eventually encourages them to die.

Dr. Theodoros Tsakiridis, study author and a radiation oncologist at the Juravinski Cancer Center and McMaster University, said, “Our study shows that the diabetes drug metformin can stop lung cancer cells from growing and makes them more sensitive to treatment by radiotherapy. “We’re now working with other institutions to develop a clinical trial that will investigate metformin in lung cancer patients treated with radiotherapy. If we can prove that this works in patients then we could have a potentially powerful weapon in the fight against the disease.”

In spite radiotherapy being an effective treatment for many cancers, it has a limited effect for lung cancer patients. Dr. Kat Arney, science information manager at Cancer Research UK (London, UK), said, “Lung cancer remains one of the most difficult cancers to treat, with less than 10% of people surviving the disease for at least five years. We urgently need new and better ways of treating lung cancer and this research takes us a step towards making radiotherapy a more potent treatment. To improve the chances for lung cancer patients, Cancer Research UK is planning to increase significantly its investment in research into this form of the disease, so that patients can benefit from new and improved treatments sooner.”

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