ESMO 2025 Adding immunotherapy improves survival in platinum-resistant ovarian cancer

MedNet.nl: After several unsuccessful studies with immune checkpoint inhibitors for ovarian cancer, there is now a positive study. In the phase 3 ENGOT-ov65/KEYNOTE-B96 study, adding pembrolizumab to weekly paclitaxel with or without bevacizumab resulted in improved progression-free survival (PFS) and overall survival (OS) in patients with recurrent platinum-resistant ovarian cancer.

The study included patients with epithelial ovarian cancer who had received one or two prior treatments, at least one of which was platinum-based chemotherapy. All patients showed radiological progression within 6 months of the last treatment with platinum-based chemotherapy. A total of 643 patients were randomized to pembrolizumab plus paclitaxel with or without bevacizumab (n=322) and to paclitaxel with or without bevacizumab (n=321). Approximately 73% of patients in both groups ultimately received bevacizumab. Approximately 73% in both groups also had a PD-L1 combined positive score (CPS) of ≥1.

After a median follow-up of 16 months, the median PFS in the PD-L1-positive group was 8.3 months versus 7.2 months in the control arm (HR=0.72, p=0.0014). In the intention-to-treat (ITT) population, the median PFS was 8.3 versus 6.4 months (HR=0.70). OS also improved with the addition of pembrolizumab: from 14.0 to 18.2 months (HR=0.76). Survival at 12 and 18 months was 69.1% versus 59.3% and 51.5% versus 38.9%, respectively. The objective response rates were 53.0% versus 46.6% in the PD-L1-positive group and 50.4% versus 40.8% in the ITT population.

Grade ≥3 adverse events occurred in 67.5% versus 55.3%. Immune-related adverse events also occurred more frequently (39.0 vs 19.0%), but these were mostly mild.

The data support the use of pembrolizumab plus paclitaxel with or without bevacizumab as the new standard treatment for patients with recurrent platinum-resistant ovarian cancer, according to the researchers.

Colombo N, et al. Pembrolizumab vs placebo plus weekly paclitaxel ± bevacizumab in platinum-resistant recurrent ovarian cancer: results from the randomized double-blind phase III ENGOT-ov65/KEYNOTE-B96 study. ESMO 2025, abstract LBA3.

This article was originally published in Dutch on MedNet.nl