A new clinical study has discovered a blood test that may help doctors predict which women with ovarian cancer are more likely to respond to a common treatment called PARP inhibitor therapy.
This important finding, published in the journal Nature Communications, could help doctors offer more personalized and effective care to thousands of women around the world.
Every year, more than 300,000 women are diagnosed with ovarian cancer worldwide, including around 1,700 in Australia. Ovarian cancer is often called the “silent killer” because its symptoms are vague and easy to miss, such as bloating or abdominal discomfort.
Many women are not diagnosed until the cancer has already spread, making treatment more difficult. The new blood test could change that by helping doctors identify the right patients for the right treatment earlier.
The study, known as SOLACE2, took place over four years and involved 15 hospitals across Australia. It was co-led by scientists from the University of Sydney’s NHMRC Clinical Trials Centre, RMIT University, and WEHI, and coordinated by the Australia New Zealand Gynaecological Oncology Group (ANZGOG).
The researchers tested ways to “prime” the immune system to make PARP inhibitor therapy work better. During the study, they discovered that a simple blood test could help identify which patients would likely benefit from the treatment.
PARP inhibitors are drugs that stop cancer cells from repairing their own damaged DNA. When this repair system is blocked, the cancer cells eventually die. These drugs are usually given to patients whose tumors have a specific DNA repair defect known as homologous recombination deficiency, or HRD.
However, not all women with HRD respond to the therapy, and some women without HRD still benefit from it. This has puzzled doctors for years, as it meant the existing HRD test wasn’t always reliable in predicting who would respond.
According to Distinguished Professor Magdalena Plebanski from RMIT University, the new test could solve this problem. Her team developed a way to measure immune system activity in the blood, focusing on how immune cells move toward and attack cancer cells.
The test looks for certain “biomarkers”—molecules in the blood that reveal how the immune system is reacting to the cancer. This simple test, which can be done with a regular blood sample, might be a better guide than the current DNA-based HRD test, which requires tumor tissue and complex analysis.
“Our test focuses on the immune system’s real-time response rather than the cancer’s DNA repair ability, which can change over time,” said Professor Plebanski. “This means we can more accurately predict which women will respond well to PARP inhibitors.”
Professor Clare Scott from WEHI, another senior author of the study, said that one of the most exciting discoveries was how immune cells inside the tumor—particularly a type called effector T cells—affect whether the treatment works.
The researchers found that when these T cells are able to move into the tumor and attack the cancer, patients respond better to treatment. In the future, doctors might be able to improve therapy by helping more of these immune cells reach the tumor.
Although the blood test is not yet available to patients, researchers are working to confirm the results in larger studies before it can be approved for clinical use. The team believes that with further testing, this approach could be used worldwide to help doctors personalize ovarian cancer treatment and improve survival rates.
The SOLACE2 clinical trial also tested a treatment strategy that used a short period of immune “priming” before starting PARP inhibitors and immunotherapy.
According to Professor Chee Khoon Lee from the University of Sydney, this approach appeared to delay cancer recurrence. However, the trial was too small to provide final proof, and more research will be needed to confirm the benefit.
Overall, the findings offer real hope for women living with ovarian cancer. The discovery of this new blood test could help doctors better match treatments to patients, avoiding unnecessary side effects and improving outcomes. If future studies confirm these results, this test could become a simple, low-cost tool to guide ovarian cancer treatment worldwide.
In reviewing the results, experts highlight both the promise and the challenges ahead. While the new test performed better than the current HRD method in predicting who benefits from PARP therapy, larger clinical trials are still needed to validate its accuracy.
The study also reinforces the growing importance of the immune system in cancer treatment and opens the door for more research into how immune responses can be measured and enhanced. If successful, this blood test could mark a major step toward more personalized and effective care for women with ovarian cancer.
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The study is published in Nature Communications.
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