Comparison of Adverse Events Between PARP Inhibitors in Patients with Epithelial Ovarian Cancer: A Nationwide Propensity Score Matched Cohort Study.

Background: Despite improvement in progression-free survival (PFS) with poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) as maintenance treatment for patients with epithelial ovarian cancer (EOC), a comparative analysis of clinical events of interest (CEIs) of different PARPi is scarce.

Objective: This study aimed to compare the safety of different PARPi in patients with EOC.

Patients and methods: Through analyzing the Korean National Health Insurance Service from January 2009 to January 2022, this study involved BRCA-mutated, platinum-sensitive patients with EOC treated with olaparib (tablet), niraparib, and olaparib (capsule) as first-line or second-line maintenance treatment. CEIs were identified using International Statistical Classification of Diseases (ICD) 9/10 codes, with additional outcomes being dose modification and persistence.

Results: In the first-line maintenance treatment [118 niraparib, 104 olaparib (tablet) patients], no significant differences were noted in CEIs, dose reduction, or 6-month discontinuation rate. For second-line maintenance treatment [303 niraparib, 126 olaparib (tablet), and 675 olaparib (capsule) patients], niraparib was associated with a higher risk of hematologic CEIs, particularly anemia, compared with olaparib (tablet) (0.51 [0.26-0.98] and 0.09 [0.01-0.74], respectively), and higher rate of discontinuation rate at 6 months. Of note, patients over 60 years old showed an increased risk of CEIs with niraparib, as indicated by the hazard ratio divergence in restricted cubic spline plots.

Conclusions: No differences were observed among the PARPi during first-line maintenance treatment. However, in the second-line maintenance treatment, significant differences were observed in the risk of experiencing CEIs, dose alteration possibilities, and discontinuation of PARPi between niraparib and olaparib (tablets). Moreover, our findings suggest that an age of 60 years may be a critical factor in selecting PARPi to reduce CEI incidence.