New data from the NeoPembrOV/GINECO trial show that in high-grade serous ovarian cancer, testing PD-L1 levels in metastatic tumors predicts response to immunotherapy better than testing the primary tumor. Patients with high PD-L1 in metastatic sites had a 54% lower risk of disease progression when treated with pembrolizumab plus chemotherapy, while primary tumor PD-L1 was not predictive.
Researchers found metastatic tumors are more “immune-enriched,” meaning they have more immune cells that immunotherapy can activate, whereas primary tumors often hide from treatment. The study included women with advanced ovarian cancer receiving pre-surgery chemotherapy with or without pembrolizumab, followed by surgery and maintenance therapy.
Additional findings showed that tumor blood vessel patterns and high levels of certain immune cells (CD3 and CD20) also correlated with longer survival. These results suggest that future testing for immunotherapy eligibility should focus on metastatic lesions rather than the original tumor.