Ovarian cancer accounts for 1.0% of all cancers and is the fifth leading cause of cancer-related death in women [1]. It is estimated that 19,710 new diagnoses and 13,270 deaths from ovarian cancer will occur in the United States in 2023 [1]. More than 70% of patients with ovarian cancer are diagnosed at an advanced stage (stages IIB–IV), with an average 5-year relative survival of 49.7% for all stages combined and 30.8% for patients with metastatic disease [2].

The primary treatments for ovarian cancer consist of debulking surgery and platinum-based chemotherapy [3], but roughly 80% of patients will relapse [4]. Therefore, first-line (1 L) maintenance therapy is used to prolong both progression-free survival (PFS) and, in some cases, may impact overall survival (OS) [4,5]. Poly (ADP-ribose) polymerase inhibitors (PARPi) are now used as targeted maintenance therapies that induce apoptosis in tumor cells by interfering with single strand break repair and base excision repair pathways [[6], [7], [8]].

PARPi (niraparib, olaparib, and rucaparib) have been associated with superior outcomes over placebo following surgery and chemotherapy, leading to their FDA approval as a maintenance strategy for patients with ovarian cancer. Olaparib was approved by the FDA in 2017 for the maintenance treatment of recurrent, epithelial ovarian cancers that showed complete or partial response to platinum-based chemotherapy, and in 2018 for the 1L maintenance treatment of BRCA-mutated (BRCAm) advanced ovarian cancers in complete or partial response to platinum-based chemotherapy, based on the phase 3 trial SOLO-1 [9]. In May 2020, the FDA approved the use of olaparib in combination with bevacizumab for 1L maintenance treatment of homologous recombination deficiency (HRD)-positive advanced ovarian cancer, based on the phase 3 trial PAOLA-1 [9]. Rucaparib received accelerated FDA approval in December 2016 [10] for treatment of patients with advanced ovarian cancer who had received at least two chemotherapy regimens and had a deleterious BRCA mutation, based on the phase 2 ARIEL2 and Study 10 trials [11]. Niraparib was approved by the FDA in April 2020 for 1L maintenance treatment of adult patients with advanced ovarian cancer who have shown complete or partial response to platinum-based chemotherapy, based on the PRIMA/ENGOT-OV26/GOG-3012 trial [12], after approval in March 2017 for maintenance treatment of adult patients with recurrent ovarian cancer who have shown complete or partial response to platinum-based chemotherapy [13,14], based on the ENGOT-OV16/NOVA trial [[15], [16], [17]].

While olaparib, rucaparib, and niraparib are all associated with improved outcomes, their safety profiles must also be considered. Higher frequencies of bone marrow suppression events and associated treatment modifications have been observed with niraparib than with olaparib and rucaparib [18]. Sackeyfio et al. conducted a meta-analysis of 25 publications from 3 clinical trials (SOLO-2, NOVA, and ARIEL3) to compare efficacy and tolerability of PARPi during the period prior to recommendations for individualized niraparib dosing. While they observed no difference in efficacy, olaparib had a superior safety profile with fewer adverse events (AEs) of grade ≥ 3 and treatment interruptions compared with niraparib and rucaparib [19]. The most common grade 3–4 AEs for niraparib in clinical trials were related to bone marrow suppression [12,17]. In addition, cardiovascular toxicities were observed in patients receiving niraparib (hypertension all grades in 19.3% and grade 3–4 in 8.2% and palpitations grades 1–2 in 10.4%) [17]. In a retrospective study from a large medical claims database prior to recommendations for individualized niraparib dosing, niraparib was more likely to be associated with hematologic AE compared with olaparib (adjusted hazard ratio [aHR] 1.51; 95% CI 1.30, 1.77; p < 0.001) and rucaparib (aHR 1.28; 95% CI 1.05, 1.57; p < 0.05). Also, niraparib was more likely to be associated with nonhematologic AE compared with olaparib (aHR 1.27; 95% CI 1.12, 1.44; p < 0.001) and all-cause inpatient admission (aHR 1.46; 95% CI 1.15, 1.84; p < 0.01) [20,21].

The prescribing information specifies that niraparib, olaparib, and rucaparib should not be initiated until hematological toxicity from previous treatments (i.e., chemotherapy) has resolved (i.e., reached Grade 1 or less). For niraparib, more frequent monitoring of complete blood counts is also required; weekly monitoring of complete blood counts for cytopenia is required for the first month and then monthly after that, versus monthly for olaparib and rucaparib [10,22,23]. Niraparib also requires monitoring for hypertensive events (blood pressure and heart rate monitored weekly or more for the first 2 months, and then monthly for the first year) [22]. In short, prior to recommendations for individualized dosing, niraparib was associated with higher toxicities compared with olaparib and rucaparib and therefore requires more frequent hematologic monitoring, and additional cardiovascular monitoring.

Such differences in monitoring requirements and safety of the three PARPi may lead to differences in healthcare resource utilization (HCRU). If these requirements are followed, we hypothesize that dose adjustments and discontinuations will be optimized to keep patients on therapy. Real-world studies make an excellent approach to understanding HCRU. Thus, in this study, we sought to understand the differences in treatment patterns and HCRU among adult patients with ovarian cancer treated with any of the three PARPi for maintenance purposes.