Pembrolizumab and Olaparib Trial Results for Ovarian Cancer
Pembrolizumab combined with chemotherapy followed by maintenance pembrolizumab and olaparib significantly prolonged progression-free survival in patients with newly diagnosed advanced BRCA non-mutated ovarian cancer, according to Phase III findings published in the Lancet Oncology. The ENGOT-OV43/GOG-3036/KEYLYNK-001 trial evaluated 1,367 patients with stage III to IV epithelial ovarian, primary peritoneal, or fallopian tube cancer lacking a BRCA1 or BRCA2 mutation. Researchers at 224 gynaecological oncology centres across 22 countries conducted the randomised, double-blind study to determine whether adding the PARP inhibitor olaparib and the immunotherapy drug pembrolizumab to standard chemotherapy could improve clinical outcomes compared to control regimens.
Trial Design and Patient Cohorts
The international trial enrolled female participants with a median age of 61 years. Following a single lead-in cycle of chemotherapy, patients were randomly assigned to one of three treatment arms. The first group received pembrolizumab plus chemotherapy followed by maintenance therapy with both pembrolizumab and olaparib. The second group received pembrolizumab plus chemotherapy followed by maintenance pembrolizumab and a placebo. The third group served as a control, receiving placebo plus chemotherapy followed by placebo maintenance. Investigators also permitted the administration of bevacizumab at their discretion.
Progression-Free Survival Outcomes
At the first interim analysis after a median follow-up of 30.1 months, the pembrolizumab and olaparib combination demonstrated a substantial survival benefit for patients with a PD-L1 combined positive score of at least 10. In this subgroup, the regimen reduced the risk of disease progression or death by 37 percent compared with the control group (hazard ratio [HR], 0.63; 95% confidence interval [CI], 0.49–0.80). Across the broader intention-to-treat population, the risk reduction reached 32 percent (HR, 0.68; 95% CI, 0.58–0.81). These benefits persisted at the final analysis after a median follow-up of 49.6 months, recording an HR of 0.66 for patients with a CPS of 10 or greater and 0.71 across the intention-to-treat population. Meanwhile, pembrolizumab administered without olaparib failed to yield a statistically significant improvement in progression-free survival in the CPS-positive population when compared against the control arm (HR, 0.95; 95% CI, 0.77–1.19; p=0.33).
Adverse Events and Toxicity Profile
Severe toxicities occurred more frequently in the dual-maintenance arm. Grade 3 or worse treatment-related adverse events affected 66 percent of patients receiving pembrolizumab and olaparib, compared to 56 percent in the pembrolizumab-alone group and 51 percent in the control cohort. The most prevalent severe side effects included neutropenia and anaemia. Serious treatment-related adverse events were documented in 24 percent of the combination group, 21 percent of the pembrolizumab group, and 9 percent of the control group. Furthermore, investigators recorded four treatment-related deaths in the pembrolizumab-olaparib arm and one in the pembrolizumab-alone arm. The study authors noted that while the regimen offers a viable first-line option for patients lacking BRCA mutations, clinicians must carefully weigh its clinical benefits against the elevated risk of toxicity.
Frequently Asked Questions
What specific patient population showed the greatest benefit from the trial regimen?
Patients with a PD-L1 combined positive score of 10 or higher experienced the most pronounced reduction in disease progression or death, achieving a 37 percent lower risk compared to the control group during the interim analysis.
How many study centres and countries participated in the trial?
The ENGOT-OV43/GOG-3036/KEYLYNK-001 trial was conducted across 224 gynaecological oncology centres located in 22 different countries.
What were the most common severe side effects associated with the pembrolizumab and olaparib combination?
The most frequent severe adverse events reported in the combination arm were neutropenia and anaemia.
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