Frontline maintenance olaparib therapy for BRCA/HRD-positive advanced epithelial ovarian cancer: real-world data analysis in matched population

Backgroundintroduction of the poly(ADP-ribose) polymerase (PARP) inhibitors to clinical practice remarkably improved outcomes for advanced epithelial ovarian cancer (EOC) patients. We conducted this study to evaluate efficacy of frontline maintenance olaparib therapy in BRCA-mutated and/or HRD-positive EOC patients in real-world practice setting. Patients and methodswe enrolled patients with FIGO stage III-IV high-grade serous or endometrioid EOC with BRCA1/2 mutations and/or HRD-positive status with complete or partial response to frontline therapy, who were treated in 2014-2024. Main objective of this trial was to compare progression-free survival (PFS) of HRD+/BRCA-mutant advanced EOC patients treated with or without maintenance olaparib in well-balanced treatment arms. Cardinality matching was considered to ensure balancing of the study arms with 1:1 ratio of patients in trial arms. The groups were balanced according to the presence of residual tumor after initial treatment, platinum-free interval duration after frontline therapy, secondary local therapy for recurrent disease, treatment with platinum drugs for relapse and subsequent bevacizumab. The primary endpoint of the study was PFS. Resultscardinality matching with 1:1 ratio resulted in 282 matched patients for the analysis. Groups were well balanced in all baseline characteristics. Median age in both treatment arms was 50 years with no differences in patients age, surgical outcomes, prevalence of BRCA-mutated or HRD-positive disease and response to initial platinum-based therapy. With a median follow up of 37.2 mo. median PFS was 38.0 in the olaparib arm and 13.7 mo. in the control arm, respectively (HR 0.32; 95% CI 0.23-0.43; p<0.001). Estimated 3-year PFS was 50.9% and 11.5%, respectively. Median PFS2 was 49.5 mo. in the olaparib arm compared to 34.3 mo. in the control arm (HR 0.58; 95% CI 0.39-0.85; p=0.005). Conclusionthis study confirms the benefits of olaparib maintenance therapy in patients with HRD- -positive and/or BRCA-mutated advanced EOC in real-world setting. HighlightsO_LIUsing cardinality matching two cohorts of patients after frontline therapy were made (treated with maintenance olaparib vs not); C_LIO_LIMedian PFS was 38.0 in the olaparib arm and 13.7 mo. in the control arm, respectively (HR 0.32; 95% CI 0.23-0.43; p<0.001); C_LIO_LIThis data confirms efficacy of maintenance olaparib for BRCA/HRD-positive advanced epithelial ovarian cancer in routine clinical practice. C_LI