Saturday 31 March 2012
Researchers have found that using the diabetes drug metformin with Avastin (bevacizumab) to treat skin cancer almost doubles its ability to block tumour growth, according to a study in Cancer Discovery*.
When treating aggressive skin cancer in mice with just avastin, tumour growth was blocked by 34 per cent. But when combined with metformin, tumour growth was suppressed by 64 per cent.
Intriguingly, when melanoma cells - the most aggressive form of skin cancer - were treated with just metformin, tumour growth increased. Scientists at The Institute of Cancer Research (ICR) found that metformin was causing melanoma cells with a BRAF mutation to secrete a protein called VEGF-A, which encourages new blood vessels to form in the tumour and increases tumour growth.
But when combined with drugs such as avastin that block VEGF-A, the dual action appeared to overcome this resistance and helped increase the effectiveness of VEGF-A inhibitors.
Professor Richard Marais, lead researcher and now director of Cancer Research UK’s Paterson Institute in Manchester, said: “Our results are surprising because combining metformin with drugs such as avastin has a much greater effect in blocking tumour growth than would be expected when looking at the effect of either drug on its own. If we can now show this effect holds true in patients, it could help overcome the resistance we often see skin cancer patients develop to drugs such as avastin. “We also need to understand the effect that metformin is having on BRAF melanomas and whether prescribing metformin could potentially worsen the disease.”
Recent research has shown that the common diabetes drug metformin has anticancer properties, and the researchers - based at and funded by the ICR, the Association of International Cancer Research and Cancer Research UK - set out to find if these effects were seen in melanoma cells containing two of the most common genetic mutations, BRAF and NRAS.
Each year around 11,800 people are diagnosed with melanoma in the UK and around half have BRAF mutations. Over the last twenty-five years, rates of malignant melanoma have risen faster than any of the most common cancers.
Dr Lesley Walker, director of cancer information at Cancer Research UK, said: “This research points the way to a potentially very effective drug combination to treat the most aggressive form of skin cancer. We now need to see if this combination benefits patients in clinical trials with the hope of making current treatments even more effective.
“Professor Marais’s team, funded by Cancer Research UK, discovered that mutations in BRAF cause around 70 per cent of malignant melanoma cases, and they are now beginning to translate this into discoveries that will benefit patients in the future.”
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Notes to editors:
*Martin, M.J. et al. Metformin accelerates the growth of BRAFV600E- driven melanoma by upregulating VEGF-A Cancer Discovery (2012)
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