274PReal-world experience of olaparib maintenance in high grade serous recurrent ovarian cancer patients with BRCA 1/2 mutation

Objective: Olaparib, a poly(ADP-ribose) polymerase (PARP) inhibitor, maintenance therapy has shown efficacy with tolerability in phase 3 trial of patients with platinum-sensitive, high-grade serous recurrent ovarian cancer (HSROC) with BRCA1/2 mutation (BRCAm). However, real-world effectiveness could be different from result of clinical trials because treatment is used in unselected, general clinical practice populations. We aimed to present real-world experience of olaparib in Korea. Methods: We included HSROC patients with BRCAm treated with olaparib maintenance at 4 institutions (Samsung Medical Center, National Cancer Center, Yonsei University Severence Hospital, and Seoul National University Hospital) in Korea between 2016 and 2018. Their medical records were reviewed retrospectively for objective response, survival outcomes and safety. Results: One hundred HSROC patients with BRCAm were treated with olaparib maintenance therapy. BRCA1 mutation was shown in 66 patients (66.0%), and BRCA2 mutation was shown in 22 patients (22.0%). Number of chemotherapy regimen before olaparib was mostly two (n=63, 63.0%) and three (n=26, 26.0%). Time to progression to chemotherapy before olaparib was median 12.8 months (range 1.0 ~86.4). For objective response to most recent chemotherapy, complete response was shown in 46 patients (46.0%), and partial response in 53 (53.0%). For best objective response with olaparib maintenance, no evidence of disease was shown in 40 patients (40.0%), partial remission in eight (8.0%) and, stable disease in 44 patients (44.0%). During follow-up period (median 10.2 month (range 1.0 ~35.7), 37 recurrences (37.0%), and five death events (5.0%) were observed. Grade 3 or more adverse events were shown in 14 patients (14.0%) with anemia, seven patients with neutropenia (7.0%), two patients with thrombocytopenia (2.0%), one patients with oral mucositis (1.0%) and soft tissue infection (1.0%). Conclusions: Safety and effectiveness of olaparib maintenance treatment in this study was consistent with the results of previous studies with tolerable toxicity profiles.