Researchers from the Walter and Eliza Hall Institute (WEHI)in Australia have found a new way to predict a subset of patients who are likely to become resistant to PARP inhibitors (PARPi), a key therapy used to treat ovarian and breast cancers in Australia. Using patient blood samples, the research team has been able to detect, for the first time, a specific process that can make ovarian cancer cells resistant to PARPi treatment—a significant finding that could enable the early detection of patients who won't respond well to the therapy. The paper is published in the journal Molecular Cancer .

Medical researchers can immediately start to look for this form of resistance using tests that are currently being used in research settings, and soon clinicians will be able to order these tests. The breakthrough will improve patient care and potentially lead to clinical trials focused on overcoming drug resistance . It is anticipated that testing for this type of resistance, using a straightforward blood test, will eventually become standard practice in both clinical and research environments.

More than 1,700 women are diagnosed with ovarian cancer and over 20,000 people are diagnosed with breast cancer in Australia every year. PARPi therapy has been a breakthrough for treating ovarian and breast cancers. In high-income countries , most patients with a DNA repair deficiency known as HRD—which can be caused by BRCA1 or BRCA2 mutations—are now receiving this treatment.

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