A newly launched companion diagnostic test is now available nationwide to help doctors identify patients with platinum-resistant ovarian cancer who may be eligible for a recently approved immunotherapy combination. The test, called PD-L1 IHC 22C3 pharmDx, is the only FDA-approved companion diagnostic for this purpose and works alongside the drugs KEYTRUDA and KEYTRUDA QLEX, which were approved by the FDA in February for this specific patient population.
Ovarian cancer is one of the most difficult cancers to treat, particularly when it becomes resistant to platinum-based chemotherapy. Approximately 80 percent of patients experience a recurrence after initial therapy, and for those whose disease becomes platinum-resistant, treatment options have historically been limited with poor survival outcomes. The new immunotherapy regimen has been shown in the Phase 3 KEYNOTE-B96 trial to reduce the risk of disease progression and improve overall survival in patients whose tumors express PD-L1, a protein that helps cancer cells evade the immune system.
The companion diagnostic works by detecting PD-L1 expression on tumor tissue samples. Patients whose tumors show a combined positive score of 1 or higher are considered eligible for treatment with KEYTRUDA plus paclitaxel, with or without the drug bevacizumab. Labcorp participated in an early validation program with Agilent Technologies to ensure the test could be rapidly deployed after FDA approval, and the company has now made it available at laboratories across the country.
What This Means for Patients
For the roughly 20,000 women diagnosed with ovarian cancer each year in the United States, the availability of this test and the associated treatments represents a meaningful advance. Platinum-resistant ovarian cancer is considered incurable, and existing therapies often provide only short-lived benefits. The ability to quickly identify which patients are likely to respond to immunotherapy could help avoid ineffective treatments and connect patients with a therapy that offers new hope.
Dr. Marcia Eisenberg, chief scientific officer at Labcorp, noted that this form of ovarian cancer is one of the most challenging to treat and that the new diagnostic tool helps clinicians rapidly identify eligible patients. The test is now available nationwide, and doctors can order it to help guide treatment decisions for patients who have already received one or two prior systemic treatments.
With the test now widely accessible and the immunotherapy regimen approved, more patients with platinum-resistant ovarian cancer may have access to a treatment option that was previously unavailable. Researchers continue to study additional approaches to improve outcomes for this difficult disease, but for now, the combination of a precise diagnostic and a targeted therapy offers a clearer path forward for eligible patients.