A blood test may be able to provide early warning that patients with advanced melanoma skin cancer are relapsing, according to a study published recently in Cancer Discovery(Girotti MR, Gremel G, Lee R et al. Application of sequencing, liquid biopsies and patient-derived xenografts for personalized medicine in melanoma.Cancer Discov 2015 Dec 29. Pii: CD-15-1336 [Epub ahead of print]).
Scientists from the Cancer Research UK Manchester Institute studied the DNA shed by tumours into the bloodstream (circulating tumour DNA) in blood samples from seven advanced melanoma patients at The Christie NHS Foundation Trust. In this early work, they found they could see whether a patient was relapsing by tracking levels of circulating tumour DNA, and they found that new mutations in genes such as NRAS and PI3K appeared, possibly causing the relapse by allowing the tumour to become resistant to treatment.
Most melanoma patients respond to treatment at first, but their cancer can become resistant within a year. It is hoped that the new approach will allow clinicians to use circulating tumour DNA to tailor treatment for individual patients in order to achieve the best result.
Around 40–50% of melanoma patients have a faulty BRAF gene, and they can be treated with the targeted drugs vemurafenib or dabrafenib. However, many of these patients do not respond to the treatment or their tumours develop resistance after a relatively short time. When this happens, these patients can be offered immunotherapy drugs including pembrolizumab, nivolumab and ipilimumab. Detecting this situation early could be key to improving their care and chances of survival.
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