Bevacizumab in first-line chemotherapy to improve the survival outcome for advanced ovarian clear cell carcinoma: A multicenter, retrospective analysis.

5502 Background: Advanced ovarian clear cell carcinoma (ACCC, stage III/IV disease) is a rare tumor characterized by chemoresistance. Bevacizumab (Bev) was approved in November 2013 in Japan and became incorporated in the treatment of advanced ovarian cancer. However, the efficacy of Bev against ACCC remain unknown. We investigated the survival outcomes for ACCC, following first-line chemotherapy with or without Bev. Methods: Patients diagnosed with ACCC at seven institutions between 2008 and 2018 were enrolled in this study. Patients underwent cytoreductive surgery and taxane-carboplatin chemotherapy (78: triweekly regimen; 30: weekly regimen; 25: dose-dense regimen; 12: others) with or without concurrent and maintenance Bev (15 mg/kg/3 weeks). We compared the progression-free survival (PFS) and overall survival (OS) before (group A, n = 102) and after (group B, n = 43) Bev approval, using Kaplan–Meier method and Cox regression model. We excluded patients with poor performance status (PS) in group A, and patients who did not receive Bev due to poor PS or thrombosis in group B. Results: There was no significant difference between two groups in terms of age (p = 0.135) and initial CA125 level (p = 0.674). Thirteen (13%) and 11 (26%) patients had stage IV disease (p = 0.058) and 2 (3%) and 7 (16%) patients were of poor PS (PS ≥2) (p = 0.004) in group A and B, respectively (p = 0.058). More patients (29/43, 67%) in group B were achieved complete resection than in A group (52/102, 51%) (p = 0.068). The median cycle of Bev in B group was 16 (interquartile range: 6-21). The median follow-up time was 36 months. The median PFS increased from 12.5months in A group to 29.7 months in B group (log-rank test: p = 0.023, Wilcoxon test: p = 0.006). The median OS increased from 34.7 months in A group to 51.4 months in B group (log-rank test: p = 0.085, Wilcoxon test: p = 0.027). Multivariate analysis revealed that Bev use (Hazard ratio (HR): 0.54, p = 0.011; HR: 0.54, p = 0.019), PS <2 (HR: 0.33, p = 0.013; HR: 0.29, p = 0.006) and completeness of resection (HR: 0.38, p < 0.001; HR: 0.37, p <0.001) were independent prognostic factors for PFS and OS. Conclusions: Incorporating Bev in first-line chemotherapy may improve PFS in patients with ACCC. [Table: see text]