DNA map offers hope on cancer treatments
Published 29/01/2013 | 10:48
CANCER will become a manageable disease rather than a death sentence thanks to a revolutionary treatment which will be available within five years, British specialists predict.
All patients will soon have their tumour’s DNA, its genetic code, sequenced, enabling doctors to ensure they give exactly the right drugs to keep the disease at bay.
Doctors hope it will be an important step towards transforming some types of cancer into a chronic rather than fatal disease.
The technique could enable terminally ill patients, who can currently expect to live only months, to carry on for a decade or more in relatively good health, according to specialists at the Institute of Cancer Research in London.
“We should be aspiring to cure cancer, but for people with advanced disease, it will be a question of managing them better so they survive for much longer – for many years,” said Prof Alan Ashworth, chief executive of the institute.
“Cancer often appears in people who are old, and if we can keep them alive long enough for them to die of something else, then we are turning cancer into a chronic disease.”
Prof Ashworth said that understanding of how different cancers were caused by different genetic triggers was building “incredibly rapidly”.
Genetic profiling of tumours is already used to some extent, but current methods only look for a few genes. Women with advanced breast cancer are tested to see if their tumours have a particular variant of the HER2 gene, which causes a fifth of cases. Those with it are given Herceptin, but the same drug would do no good for those without the gene variant.
Advanced melanoma patients with a particular gene mutation are prescribed Vemurafenib, a pill that has been shown to increase survival, on average, from 9.6 to 13.2 months, and help patients feel much more energetic.
But average survival times hide massive variations. One patient at the Royal Marsden in Chelsea, where the institute is based, has survived 10 years so far with advanced breast cancer on Herceptin.
Prof Ashworth said that such cases were the exception.
But he added: “We would hope that they will become the norm. By actively profiling patients who respond well, and sequencing their genomes, we can find the genes that are responsible for that.”
The institute wants to build a DNA database to identify lots of genes responsible for cancers. It is launching a three-year, £3?million project called the Tumour Profiling Unit to advance knowledge of the genetic profile of cancer.
Prof Ashworth said: “None of this is science fiction. One would think in five or 10 years this will be absolutely routine practice for every cancer patient.”
He thought the method would have “a big impact” on a range of cancers within a decade, but added: “Over the next two to three years, there will be individual patients who receive substantial benefits from these technologies.”
He also thought genetic profiling would make developing new drugs quicker and less expensive.
But tumours can sometimes develop resistance to drugs in months.
Scientists hope to counter this by monitoring tumour DNA. Currently, this requires repeated biopsies, which are invasive. Scientists at the institute are developing a blood test to examine free-floating DNA from tumours instead.
Prof Ashworth admitted that personalised cancer medicine was in its “early days”. Resistance to drugs was a major obstacle, he said. “People have described this as a game of whack-a-mole – you knock one on the head and another comes up,” he said.
“But this isn’t black magic. The knowledge is accumulating incredibly rapidly. Despite the setbacks, most people are optimistic.”
One implication is the use of drugs designed for one cancer on a different type, if they share the same genetic cause.
Charlotte Beardmore, of the Society and College of Radiographers, described personalised cancer drugs as a “fantastic” development.
But she cautioned: “We will still need other treatments too, we won’t replace them.”
Prof Jane Maher, chief medical officer at Macmillan Cancer Support, said: “The concept in principle is a really exciting one. But technologically there are real challenges in knowing how quickly this will happen.”
She said that tumours were often genetic mosaics and very good at developing resistance.
By Stephen Adams, Telegraph.co.uk