The Overtreatment and Cost Effectiveness of Primary versus Secondary Maintenance Therapy with Poly-Adenosine Ribose Phosphate Inhibitors (PARPi) for Epithelial Ovarian Cancer (EOC).

Background: No data exist to suggest PARP inhibitor (PARPi) therapy as first-line maintenance is superior to PARPi therapy as second-line maintenance.

Objective: To determine the efficacy and cost of primary versus secondary olaparib or niraparib maintenance in Epithelial Ovarian Cancer (EOC).

Methods: A retrospective cohort study was performed in women with EOC to determine the survival following primary or secondary PARPi maintenance. We modeled the costs of olaparib and niraparib based on previously published costs and duration of therapy based on the Solo 1/Solo 2 and Prima and Nova trials, respectively.

Results: Among 40 patients treated with PARPi as primary or secondary maintenance there was no difference in overall survival (p=0.97). Among 166 women with stage III/IV germ-line BRCA mutated EOC, 28.8% were disease free for >3 years (18.6% never recurred and 10.2% recurred >3 years after chemotherapy). Since 29% of the BRCA mutated patients did not recur within 3 years, primary olaparib maintenance therapy was significantly more expensive than secondary olaparib maintenance therapy by 260%. Primary niraparib maintenance therapy was slightly more expensive than secondary niraparib maintenance therapy by 4%, 51%, and 15% for BRCA mutated, HR deficient, and HR proficient patients, respectively. By eliminating the overtreatment of patients with primary PARPi therapy, the cost savings for 100 women with EOC with BRCA mutations would be $37,335,360 for olaparib and $8,197,592 for niraparib.

Conclusion: Up to 29% of BRCA mutated patients may be overtreated with primary PARPi maintenance with significantly increased treatment costs.