With our new grants for research into the uses of liquid biopsies, Dr Sophie Lutter explains why they allow scientists to read clues about how a prostate cancer responds to treatment, and how they could revolutionise the way men are diagnosed and monitored with the disease.
At the moment, precision medicine – that is finding the right drug for the right man at the right time – is the watch-word of the day. It’s what experts around the world are predicting to become the new gold standard for prostate cancer care.
But what actually needs to happen to find out which changes in a man’s tumour DNA are driving his cancer and could be targeted with treatment?
The truth is that prostate cancers have always sent out clues to their molecular weaknesses, but it’s taken years of research to reach the point where we can not only see those clues, but also start to unravel their meaning. It’s just like a 'cold case' crime scene. The clues were always there, but until we understood how to use a fingerprint – or later on, a trace of DNA evidence – we didn’t know that these were clues, or understand how they could help us identify the criminal.
Liquid biopsies could predict how serious a man’s cancer might be, work out which treatment will work best for him, and monitor how well he responds
It’s very similar with cancer, except we’re not quite at the 'solving cold cases' stage yet. Scientists have known that cancers shed cells and genetic material into the bloodstream for a while. But the technology to be able to isolate the tumour cells and DNA from normal cells and DNA in the blood, and then to 'read' and interpret what it means, is only really coming into its own now.
This technology is called a liquid biopsy. It’s still being developed, and it represents the real cutting edge of prostate cancer therapeutics. Liquid biopsies could potentially be used to predict how serious a man’s cancer might be, work out which treatment will work best for him, and monitor how well he’s responding to treatment. If the treatment isn’t working, a liquid biopsy can help doctors understand why.
This just isn’t possible with a traditional biopsy. While some genetic changes may be present in the tumour from the time a man is first diagnosed (and has his first prostate biopsy taken), most cancers will evolve during the course of the disease. They acquire more and more mutations that can affect how the cancer responds to treatment.
On top of this, not all cells are the same. Some cells in the same tumour may have a different genetic make-up to other cells. And finally, if the cancer grows and spreads outside the prostate and forms secondary tumours elsewhere in the body, the genetic changes in those tumours may well be different to those in the main prostate cancer.
This means that it’s quite possible that a traditional biopsy, even of the secondary tumours, could miss the cells – or even the tumours – that have the key mutations we need to find. It would be like looking for a needle in a haystack.
Not only that, but once a man is already receiving treatment, if doctors want to monitor how well he’s doing, a series of traditional biopsies – especially of secondary tumours – just isn’t practical. Not only would this be physically demanding and incredibly invasive for a man who may well be feeling increasingly poorly anyway, but it would also be very expensive and time consuming.
The demands on the patient from a liquid biopsy are very slight – it’s just a blood test
On the other hand, the demands on the patient from a liquid biopsy are very slight – it’s just a blood test. This can be done every time the man comes in to see his doctor. And because the tumour cells or DNA circulating in the blood are likely to come from all parts of all tumours, there’s a higher chance that this will reveal the clues to which new treatment will work best, how well a current treatment is treating a man’s cancer, or why a treatment may not be working as well as expected.
Repeated testing also allows for quick action. Right now, if a drug stops working, it's only when the man’s PSA levels start to rise and/or imaging shows his tumours are starting to grow again that a new treatment option might be given. But what if we didn’t have to wait for these physiological changes? What if we could track the moment the cancer’s DNA changes to make it resistant to treatment?
With liquid biopsies, that may well be the reality and a man could save precious time, and possibly increase his quality of life, by not continuing to take a treatment that is no longer working for him with all the side effects that entails.
Developing, refining and validating this new technology to get it into the clinic as soon as possible is going to play a big part in cancer research over the next few years, and cancer treatment in the years after that. It’s important that prostate cancer doesn’t get left behind.
That’s why we’re already using funds from the Movember Foundation to support projects that will use liquid biopsies to deliver precision medicine to men with prostate cancer. You can read more about these projects in our news story and on our funded research pages.