The study, titled “Application of sequencing, liquid biopsies and patient-derived xenografts for personalized medicine in melanoma,” was led by scientists from the Cancer Research UK Manchester Institute in England and analyzed circulating tumor DNA – the DNA traces left by tumors in patients’ bloodstream – in blood samples of seven patients with advanced melanoma at The Christie NHS Foundation Trust.
The team found they could identify whether a patient was relapsing by tracking circulating tumor DNA levels. And they found new mutations in the genes NRAS and PI3K, which could be one of the causes for relapse, enabling the tumor to become increasingly resistant to treatment.
Nearly half of all melanoma patients have a faulty BRAF gene and are usually treated with the drugs dabrafenib or vemurafenib. But even though most patients start by responding well to treatment, their cancer usually becomes resistant to therapies within a year. They can then be treated with the immunotherapy drugs pembrolizumab, nivolumab, and ipilimumab, but only detecting the tumor at an early stage can improve this situation definitively.
Testing patients through blood samples will hopefully enable doctors to use circulating tumor DNA to personalize treatment for individual patients.
“Being able to spot the first signs of relapse, so we can rapidly decide the best treatment strategy, is an important area for research,” Prof. Richard Marais, the study’s main author and a Cancer Research UK’s skin cancer expert, said in a press release. “Using our technique we hope that one day we will be able to spot when a patient’s disease is coming back at the earliest point and start treatment against this much sooner, hopefully giving patients more time with their loved ones.
“Our work has identified a way for us to do this but we still need to test the approach in further clinical trials before it reaches patients in the clinic,” Marais said.
“One of the sinister things about melanoma is that it can lay dormant for years and then suddenly re-emerge, probably as it escapes from the control of the body’s immune system,” said Prof. Peter Johnson, chief clinician for Cancer Research UK. “Being able to track cancers in real time as they evolve following treatment has huge potential for the way we monitor cancers and intervene to stop them growing back. There’s still some time until we see this in the clinic, but we hope that in the future, blood tests like these will help us to stay one step ahead in treating cancer.”