Non-interventional study OVATAR final report: Diagnostic and treatment approaches in Russian ovarian cancer population—BRCAm group analysis.

e13111 Background: First large Russian ovarian cancer observational study was conducted in 2014-2018. Methods: A total of 500 patients in 29 sites in Russia with newly diagnosed ovarian, peritoneal and fallopian tube cancer was enrolled (NCT02122588). The primary objective was to describe treatment approaches in the first line treatment. 141 patients (pts) with BRCA1/2 mutations (BRCA1/2mt) detected by NGS in blood and tissue were observed prospectively during at least 2 years. Results: Rate of BRCA1/2 mutations in Russian population is high – 28.4% (141 from 496 available for any testing). 77.6% (388/500) underwent biomarkers blood testing prior to treatment. CA-125 was positive in 99.7% (387/388), 15.2% (59/388) of pts had positive CA19-9, CA72-4 - in 2.3% (9/388). Positive CEA was presented in 15.2% (59/388). This marker was detected more frequently in BRCA2mt pts subgroup (28.0% (7/25)) than in BRCA1mt pts: 9.0% (8/90) (p = 0.05). 26.6% (133/500) of all study population had an oncology family history; 44.0% (62/141) BRCA1/2mt pts had relatives with oncological diseases and 19.7% (70/355) in BRCA wild type pts (p = 0.0001). 98.6% (139/141) of BRCA1/2mt pts received first line therapy. Objective response rate was registered in 79.8% (111/139) pts. Progression after platinum based regimens was observed in 53.6% (59/110) BRCA1mt pts and 44.8% (13/29) BRCA2mt pts. 35.6 % (21/59) of BRCA1mt pts had platinum-refractory and platinum-resistant relapses, while 15.4% in BRCA2mt subgroup (2/13) (p = 0.64). Platinum-sensitive relapses were in 64.4% (38/59) BRCA1mt pts and 84.6% BRCA2mt (11/13) (p = 0,64). Median PFS in BRCA1/2mt pts was 25.5 months. Among BRCA1/2mt pts underwent cytoreduction median PFS in subgroup without visible residual tumor was 36.4 months and in subgroup with residual tumor < 1 cm 15.3 months. Conclusions: In this large-scale prospective non-interventional study diagnostics and treatment approaches in Russian ovarian cancer pts were evaluated and high frequency of BRCA1/2mt was observed. Pts with BRCA1/2mt had better prognosis and most of them had platinum-sensitive relapses after first line chemotherapy that allowed platinum-based regimen rechallenge.