Scientists have worked out a way of predicting how long a prostate cancer patient will continue to respond to the PARP inhibitor drug olaparib, according to new research published in the journal Cancer Cell . A team from The Institute of Cancer Research, London, used a simple blood test to detect the presence of genomic changes that affect how well the drug can act on cancer. They saw a clear link between the number of certain DNA changes—called reversion mutations—a patient had and how long they survived.

The researchers also discovered that for patients with cancers missing the BRCA2 gene—who initially responded well to treatment—the cancer developed resistance to olaparib by regaining copies of this gene. Results will pave the way to new treatments PARP inhibitors such as olaparib have transformed treatment for advanced prostate cancer in recent years, but the length of time that patients respond to the medicine varies widely. The drug will eventually stop working for all patients and their cancers will continue to grow.

Being able to predict when and how patients will stop responding to a particular drug helps doctors to personalize treatment as it means they can switch patients to a different regimen. The researchers also hope the results will pave the way for the development of new drugs that target these genetic changes, preventing advanced prostate cancers from becoming resistant to treatment. The researchers analyzed multiple blood samples from 25 patients wi.