New blood test results reveal potential of liquid biopsies to deliver precision medicine for prostate cancer.
Researchers at the Institute of Cancer Research have created a powerful new three-in-one blood test, which could help doctors monitor whether a treatment is working and how a man’s cancer is responding. We examine the results and find out why it’s another step in the creation of targeted treatments for prostate cancer.
A new blood test has revealed the potential for liquid biopsies to help select patients for treatment and monitor their response for early signs of treatment resistance.
Professor Johann de Bono [pictured above] and his team at the Institute of Cancer Research have unveiled the results of blood sample analysis from men with hormone resistant prostate cancer, who were taking part in a clinical trial of a drug called olaparib. This work, published today in the journal Cancer Discovery and funded in part by Prostate Cancer UK, revealed that changes in the amount of cancer DNA circulating freely in the men’s blood was closely linked to how well the treatment was working for them.
After eight weeks, the total concentration of cancer DNA in the blood had dropped by nearly 50 per cent in men for whom the treatment worked, while it increased by around two per cent in men who did not respond to treatment. This in turn corresponded to the men’s survival time. Those whose levels of circulating tumour DNA dropped after eight weeks survived an average of seven months longer than the men whose levels didn’t fall.
A potentially powerful three-in-one test
What this all suggests is that a blood test – or liquid biopsy – could routinely be used in the future to tell how well a man is responding to treatment much earlier than is currently possible, so he can make a timely switch to a treatment that might work better.
“Our study identifies, for the first time, genetic changes that allow prostate cancer cells to become resistant to the precision medicine olaparib,” says Professor Johann de Bono, who led the research. “From these findings, we were able to develop a powerful, three-in-one test that could, in future, be used to help doctors select treatment, check whether it is working and monitor the cancer in the longer term.
“We think it could be used to make clinical decisions about whether such PARP-inhibitor drugs, like olaparib, are working within as little as four to eight weeks of starting therapy. Not only could the test have a major impact on treatment of prostate cancer, but it could also be adapted to open up the possibility of precision medicine to patients with other types of cancer as well.”
Creating targeted treatments to save more men’s lives
The researchers also did a more detailed analysis of the DNA to look at what had changed at the point that the men’s cancer progressed. They found a number of new genetic changes, including mutations in some cases that directly cancelled out the effect of the drug. This sort of in-depth analysis could not only help tell researchers when the disease stops responding to treatment, but more importantly why it is no longer responding. In turn, the identification of new gene alterations could suggest new treatments that might work better.
“To greatly improve the survival chances of the 47,000 men diagnosed with prostate cancer each year, it’s clear that we need to move away from the current one-size-fits-all approach to much more targeted treatment methods,” says Dr Matthew Hobbs, Deputy Director of Research at Prostate Cancer UK. “The results from this study and others like it are crucial, as they give an important understanding of the factors that drive certain prostate cancers or make them vulnerable to specific treatments.
“However, there is still much more to understand before the potentially huge benefits of widespread precision treatment for prostate cancer will reach men in clinics across the UK. That is why Prostate Cancer UK is investing so heavily in this area, including supporting this research released today. We can only do this, and continue to fund the next steps of research like this, through the hard work and generosity of our supporters.”