Real-world clinical practice: Toxicities of maintenance PARP inhibitors in recurrent ovarian cancer—The Royal Marsden experience.

e18770 Background: Maintenance therapy with PARP inhibitors (PARPi) in recurrent high grade ovarian cancer is standard of care for patients who have responded to second or subsequent lines of platinum-based chemotherapy. The increased access to PARP inhibitors (Olaparib, Niraparib and Rucaparib) has provided the opportunity to explore the real-world toxicities in routine clinical practice, toxicity management and the consequent impact on maintenance therapy outcomes. Methods: Patients with relapsed ovarian cancer that received maintenance PARP inhibitor therapy in routine clinical practice between April 2015 and April 2020 were identified. Electronic patient records were reviewed retrospectively to retrieve details of any reported toxicities (occurring at any time during therapy) and their management. Data was entered into and analysed in a Microsoft Excel spreadsheet. Results: 99 patients who received second or subsequent line maintenance PARPi therapy were included (median age 63.6 years). 36% had a germline BRCA1/2 mutation, 6% had a somatic BRCA1/2 mutation and 58% were BRCA wild-type. 69% received 2nd line maintenance therapy; 22% and 9% received a maintenance PARP inhibitor following 3rd or 4+ line therapy respectively. 56% had not received previous maintenance therapy; 43% had received Bevacizumab. 48% patients commenced maintenance therapy at full dose. 13% of patients experienced no toxicities. 60% of patients experienced G1-2 toxicities, with 42% experiencing >2 episodes; most common toxicities were fatigue, nausea/vomiting and thrombocytopenia. 26% of patients experienced >G3 toxicity, with 9% experiencing >2 episodes, 4% of which were recurring toxicities; most common toxicities were hypertension, neutropenia and anaemia. 64% of patients developed toxicity within the first cycle of treatment; 39% had a dose interruption, 56% of which were < 2 weeks duration. 59% patients required a dose reduction from their starting dose due to toxicities. There was no significant difference in median PFS between patients who had been dose reduced compared to those who received full starting dose (p > 0.05). Conclusions: In keeping with phase III clinical trials, our real-world experience is that most PARPi toxicities are low grade and occur early in treatment. Toxicities can be effectively managed with brief dose interruptions and dose reductions, without adverse impact on survival outcomes.