Scientists unravel cause of second cancer arising from targeted treatment
ICR scientists have shown how to prevent new cancers which can occur when malignant melanoma patients are treated with drugs known as BRAF inhibitors.
Professor Richard Marais and his collaborators from around the world examined squamous cell carcinoma tissue taken from 21 malignant melanoma patients who had been treated with vemurafenib in a clinical trial. Sixty per cent of the samples harboured cancer-causing mutations in either the HRAS or KRAS genes.
Further testing demonstrated that the BRAF inhibitors accelerate the development of existing cancerous changes to the skin that were not yet showing symptoms. It was also discovered that another type of drug – called a MEK inhibitor – could block the development of these second tumours even in the presence of the BRAF drugs.
Professor Marais said: “Around half of all patients with malignant melanoma have a mutation in their BRAF gene, and can be treated with BRAF-inhibiting drugs. However, between 15 and 30 per cent of the treated patients develop other skin tumours. By determining the mechanism by which these develop, we have been able to devise a strategy to prevent the second tumours without blocking the beneficial effects of the BRAF drugs. This may allow many more patients to benefit from these important drugs.”
