Maintenance olaparib rechallenge in patients with platinum-sensitive relapsed ovarian cancer previously treated with a PARP inhibitor (OReO/ENGOT-ov38): a phase IIIb trial

Abstract

•OReO is the first study to show that maintenance olaparib rechallenge provides a PFS benefit in relapsed ovarian cancer.•Statistically significant PFS benefit is seen with olaparib rechallenge over placebo independent of BRCA mutation status.•A proportion of the OReO population was still progression free at 1 year.•No new safety signals were observed with maintenance olaparib rechallenge.•Further investigation may reveal identifiable characteristics of those patients deriving the most clinical benefit. BackgroundPoly(ADP-ribose) polymerase (PARP) inhibitor maintenance therapy is the standard of care for some patients with advanced ovarian cancer. We evaluated the efficacy and safety of PARP inhibitor rechallenge.Patients and methodsThis randomized, double-blind, multicenter trial (NCT03106987) enrolled patients with platinum-sensitive relapsed ovarian cancer who had received one prior PARP inhibitor therapy for ≥18 and ≥12 months in the BRCA-mutated and non-BRCA-mutated cohorts, respectively, following first-line chemotherapy or for ≥12 and ≥6 months, respectively, following a second or subsequent line of chemotherapy. Patients were in response following their last platinum-based chemotherapy regimen and were randomized 2 : 1 to maintenance olaparib tablets 300 mg twice daily or placebo. Investigator-assessed progression-free survival (PFS) was the primary endpoint.ResultsSeventy four patients in the BRCA-mutated cohort were randomized to olaparib and 38 to placebo, and 72 patients in the non-BRCA-mutated cohort were randomized to olaparib and 36 to placebo; >85% of patients in both cohorts had received ≥3 prior lines of chemotherapy. In the BRCA-mutated cohort, the median PFS was 4.3 months with olaparib versus 2.8 months with placebo [hazard ratio (HR) 0.57; 95% confidence interval (CI) 0.37-0.87; P = 0.022]; 1-year PFS rates were 19% versus 0% (Kaplan–Meier estimates). In the non-BRCA-mutated cohort, median PFS was 5.3 months for olaparib versus 2.8 months for placebo (HR 0.43; 95% CI 0.26-0.71; P = 0.0023); 1-year PFS rates were 14% versus 0% (Kaplan–Meier estimates). No new safety signals were identified with olaparib rechallenge.ConclusionsIn ovarian cancer patients previously treated with one prior PARP inhibitor and at least two lines of platinum-based chemotherapy, maintenance olaparib rechallenge provided a statistically significant, albeit modest, PFS improvement over placebo in both the BRCA-mutated and non-BRCA-mutated cohorts, with a proportion of patients in the maintenance olaparib rechallenge arm of both cohorts remaining progression free at 1 year. Poly(ADP-ribose) polymerase (PARP) inhibitor maintenance therapy is the standard of care for some patients with advanced ovarian cancer. We evaluated the efficacy and safety of PARP inhibitor rechallenge. This randomized, double-blind, multicenter trial (NCT03106987) enrolled patients with platinum-sensitive relapsed ovarian cancer who had received one prior PARP inhibitor therapy for ≥18 and ≥12 months in the BRCA-mutated and non-BRCA-mutated cohorts, respectively, following first-line chemotherapy or for ≥12 and ≥6 months, respectively, following a second or subsequent line of chemotherapy. Patients were in response following their last platinum-based chemotherapy regimen and were randomized 2 : 1 to maintenance olaparib tablets 300 mg twice daily or placebo. Investigator-assessed progression-free survival (PFS) was the primary endpoint. Seventy four patients in the BRCA-mutated cohort were randomized to olaparib and 38 to placebo, and 72 patients in the non-BRCA-mutated cohort were randomized to olaparib and 36 to placebo; >85% of patients in both cohorts had received ≥3 prior lines of chemotherapy. In the BRCA-mutated cohort, the median PFS was 4.3 months with olaparib versus 2.8 months with placebo [hazard ratio (HR) 0.57; 95% confidence interval (CI) 0.37-0.87; P = 0.022]; 1-year PFS rates were 19% versus 0% (Kaplan–Meier estimates). In the non-BRCA-mutated cohort, median PFS was 5.3 months for olaparib versus 2.8 months for placebo (HR 0.43; 95% CI 0.26-0.71; P = 0.0023); 1-year PFS rates were 14% versus 0% (Kaplan–Meier estimates). No new safety signals were identified with olaparib rechallenge. In ovarian cancer patients previously treated with one prior PARP inhibitor and at least two lines of platinum-based chemotherapy, maintenance olaparib rechallenge provided a statistically significant, albeit modest, PFS improvement over placebo in both the BRCA-mutated and non-BRCA-mutated cohorts, with a proportion of patients in the maintenance olaparib rechallenge arm of both cohorts remaining progression free at 1 year.