Blood Test Guides More Effective Ovarian Cancer Treatment

Ovarian cancer affects hundreds of thousands of women worldwide each year, yet only some respond to PARP inhibitor therapy, which targets tumors with defective DNA repair. Clinicians have long observed that response patterns do not align neatly with current testing methods, leaving many women over- or undertreated. Now, a four-year clinical trial has uncovered a potential blood-based solution that may more accurately predict who will benefit from this therapy.

In the SOLACE2 Phase II trial conducted across 15 Australian hospitals, researchers at the University of Sydney NHMRC Clinical Trials Centre (Sydney, NSW, Australia), RMIT University (Melbourne, VIC, Australia), and WEHI (Melbourne, VIC, Australia), tested strategies to prime the immune system before administering PARP inhibitors. In addition to focusing on therapeutic combinations that block the PARP enzyme and prevent cancer cells from repairing damaged DNA, the team also evaluated a new companion blood test for women with ovarian cancer that showed promising results.

Image: RMIT’s Distinguished Professor Magdalena Plebanski and WEHI’s Professor Clare Scott AM in the lab (Photo courtesy of WEHI)

The blood-based immune test could improve treatment selection by measuring changes in immune biomarkers that show the movement of cancer-destroying immune cells toward hidden tumor sites, along with inflammatory markers linked to growth and resistance. This approach aims to capture a real-time biological “signature” that reflects how susceptible a patient’s cancer may be to PARP inhibition.

During the trial, the immune-based test identified women more likely to respond to PARP inhibitors regardless of whether their tumors were classified as HRD positive or HRD negative. The results, reported in Nature Communications, showed that the patented biomarker panel outperformed the current HRD test in predicting benefit. Because the HRD test requires adequate tumor tissue and complex DNA repair analysis, it often misses dynamic changes in tumor behavior that evolve over a period of time.

Investigators also found that immune cell movement—especially migration of effector T cells into tumors—was a key factor influencing therapeutic response. The trial further showed that three months of immune priming delayed recurrence when followed by PARP inhibitor therapy and immunotherapy, although this result requires further validation.

The findings demonstrate that a simple blood draw may offer a more accurate and accessible method for selecting women who will benefit from PARP inhibitor treatment. By focusing on the body’s current immune response rather than older DNA repair markers, the test may enable more personalized, effective care. Researchers also note that understanding immune-cell migration could help refine combination therapies in the future.

The test is not yet available clinically and requires additional validation before regulatory approval. Ongoing collaborations among trial partners aim to refine the assay, confirm its predictive accuracy in larger studies, and integrate immune-guided personalized treatment approaches into ovarian cancer care.

“In SOLACE2, we demonstrated that a new immune test could better indicate which women will respond to PARP inhibitors,” said RMIT lead researcher and co-senior author, Distinguished Professor Magdalena Plebanski. “We expect this promising new test will enable more effective screening and identification of eligible patients for PARP inhibitors, allowing us to provide this leading treatment to the women most likely to benefit.”

Related Links:
University of Sydney NHMRC Clinical Trials Centre
RMIT University
WEHI