Abstract 542P
Background
The therapeutic effect of PARP inhibitors (PARPi) monotherapy compared with platinum-based chemotherapy, and the impact of subsequent platinum-based chemotherapy after PARPi resistance were inconclusive in BRCA1/2-mutant ovarian cancer patients with secondary platinum-sensitive relapse.
Methods
Patients in this study were all carried with germline BRCA1/2 pathogenic mutation without any maintenance regimen after first- and second-line platinum-therapy, and the secondary platinum-free interval (PFI) was more than 6 months. Patients in the study group were treated with PARPi monotherapy until disease progression, and platinum-based chemotherapy in control group without restriction on specific type or dose.
Results
A total of 64 patients were retrospectively analyzed, including 31 (48.4%) in the study group and 33 (51.6%) in the control group. The objective response rate (ORR: 77.4% vs. 84.0%, p=0.538) and median progression-free survival (mPFS: 8.6 vs. 11.1 months, p=0.679) were comparable. PARPi monotherapy significantly prolonged post-recurrent survival (PRS, HR=0.35, 95% Cl 0.14 to 0.86, p=0.022), and was the independent factor associated with PRS (HR=0.35, 95%CI 0.11-0.92, p=0.034) in multivariate analysis. The median time from treatment to first subsequent therapy or death (TFST) of patients with platinum-based chemotherapy after PARPi progression and patients in control group with PFI≥6months after third-line platinum chemotherapy was comparable (mTFST: 5.9 vs. 7.1 months, HR=1.39, p=0.437). Further analysis showed that PRS of patients in study group was similar to patients with PFI≥6 months after third-line platinum chemotherapy (HR=0.66, 95%CI 0.19 to 2.24, p=0.503), and superior to patients with PFI<6 months after third-line platinum chemotherapy (HR=0.14, 95%CI 0.03 to 0.57, p=0.006).
Conclusions
The therapeutic effect of PARPi monotherapy and platinum-based chemotherapy was equivalent for BRCA1/2-mutant ovarian cancer patients with secondary platinum-sensitive recurrence. The prolonged PFI with PARPi monotherapy did not negatively affect the outcome of subsequent platinum-based chemotherapy and could improve prognosis.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.