UK-based scientists have developed a new three-in-one blood test able to identify the patients with advanced prostate cancer most likely to benefit from PARP inhibitors, with the potential to ‘transform’ treatment of the disease.

By testing cancer DNA in the bloodstream, researchers from The Institute of Cancer Research (ICR), London, and The Royal Marsden NHS Foundation Trust, were also able to pick out patients not responding to treatment so that they could be switched to alternative therapy in just four to eight weeks.

The test was also used to monitor a patient’s blood throughout treatment to quickly determine if the cancer was evolving and thus becoming resistance to treatment.

The researchers claim the test is the first developed for a precision prostate cancer therapy targeted at specific genetic mutations with tumours, and believe it could allow the PARP inhibitor olaparib (AstraZeneca’s Lynparza) to become a standard treatment for advanced prostate cancer.

“Our study identifies, for the first time, genetic changes that allow prostate cancer cells to become resistant to the precision medicine olaparib,” said Professor Johann de Bono, Regius Professor of Cancer Research at The ICR and consultant medical oncologist at The Royal Marsden NHS FT.

“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 a PARP inhibitor is 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.”

Dr Matthew Hobbs, deputy director of Research at Prostate Cancer UK, said the results from the 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,” he cautioned.

The study is published in the journal Cancer Discovery, and was funded by the Prostate Cancer Foundation, Prostate Cancer UK, The Movember Foundation, Cancer Research UK and the National Institute for Health Research (NIHR) via the Experimental Cancer Medicine Centre Network, and the NIHR Biomedical Research Centre at The Royal Marsden and the ICR.