In routine clinical practice, toxicities from PARP inhibitor therapy in patients with relapsed ovarian cancer are low grade and occur early in treatment, consistent with phase 3 trials clinical trials, according to a study presented at the virtual 2021 ASCO Annual Meeting.

“Maintenance therapy with PARP inhibitors… in recurrent high grade ovarian cancer is standard of care for patients who have responded to second or subsequent lines of platinum-based chemotherapy,” wrote Zohra Ali, MBBS, MRCP, The Royal Marsden NHS Foundation Trust, London, United Kingdom, and colleagues.

“The increased access to PARP inhibitors has provided the opportunity to explore the real-world toxicities in routine clinical practice, toxicity management and the consequent impact on maintenance therapy outcomes,” they continued.

Dr Ali and colleagues identified patients with relapsed ovarian cancer that received maintenance PARP inhibitors in routine clinical practice between April 2015 and April 2020. Electronic patient records were retrospectively reviewed for data on toxicities and their management.

A total of 99 patients were included in the study, of whom 36% had a germline BRCA1 or BRCA2 mutation and 58% were BRCA wild-type. 69% of patients received second-line maintenance therapy; of whom 22% received a maintenance PARP inhibitor following third-line therapy and 9% following fourth-line therapy. 56% of patients had not received prior maintenance therapy; 43% received bevacizumab. 48% patients started maintenance therapy at the full dose.

Overall, 13% of patients experienced no toxicities. 60% of patients experienced grade 1-2 toxicities, 42% of whom experienced >2 episodes. The most common grade 1-2 toxicities were hypertension, neutropenia, and anemia. 26% of patients experienced grade 3 or greater toxicity, 9% of whom experienced >2 episodes and 4% of which were recurring toxicities. The most common grade 3 or greater toxicities were hypertension, neutropenia and anemia.

64% of patients developed toxicity within the first cycle of treatment and 39% had a dose interruption, 56% of which were >2 weeks in duration. In addition, 59% of patients needed a dose reduction from their starting dose.

No significant difference in median progression-free survival was noted between patients who had dose reductions compared to those receiving full dose (P >.05)

“In keeping with phase 3 clinical trials, our real-world experience is that most PARP inhibitor 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,” concluded Dr Ali and colleagues.—Janelle Bradley

Zohra Ali, Appadu L, Kitetere E, et al. Real-world clinical practice: Toxicities of maintenance PARP inhibitors in recurrent ovarian cancer—The Royal Marsden experience. Presented at: the 2021 ASCO Annual Meeting; June 4-8, 2021; virtual. Abstract e18770.