Response to Chemotherapy and Clinical Outcome of Patients With Recurrent Epithelial Ovarian Cancer After PARP Inhibitor Maintenance Treatment: A Multicenter Retrospective Italian Study.

Background/aim: To assess response rates and survival in patients with recurrent platinum-sensitive epithelial ovarian cancer (EOC) who received PARP inhibitor (PARP-i) maintenance and who subsequently underwent salvage chemotherapy for disease progression after PARPi.

Patients And Methods: This retrospective investigation analyzed 103 patients who were treated in five Italian Gynecologic centers. The PARPi used was olaparib in 46 patients, niraparib in 55, and rucaparib in 2. The interval time between the last cycle of pre- PARPi platinum-based chemotherapy and the diagnosis of progression during PARPi maintenance was defined as platinum-free interval (PFI).

Results: Of the 28 patients with PFI <6 months, 23 received chemotherapy (non-platinum single agent, 20; trabectedin + pegylated liposomal doxorubicin (PLD), 3). Forty-two of the 43 patients with PFI 6-12 months underwent chemotherapy (platinum-based chemotherapy,11; trabectedin + PLD, 10; non platinum-single agent, 21). Thirty-one of the 32 patients with PFI >12 months received chemotherapy (platinum-based chemotherapy, 23; trabectedin + PLD, 3; non platinum - single agent, 5). An objective response was found in 13.0%, 26.2% and 41.9 % of the patients with PFI <6 months, 6-12 months, and >12 months (p= 0.03), respectively, and the corresponding median survivals after PARPi were 8.9 months, 17.5 months and 24.1 months (p= 0.002), respectively.

Conclusion: Before the PARPi era, some randomized trials on platinum rechallenge in patients with recurrent EOC after more than 6 months from the last platinum cycle have shown response rates ranging from 47.2% to 66%. Response rates to chemotherapy for progression after PARPi appear to be lower than those expected according to PFI.