Introduction/Background In low-grade serous ovarian cancer (LGSOC), surgery remains the cornerstone of treatment. However, not all patients are candidates to complete primary resection and will be offered platinum chemotherapy with expected low response rates (<5%). Whether adding bevacizumab may improve response to platinum chemotherapy in LGSOC is poorly described.

Methodology We identified patients with advanced or metastatic LGSOC treated at Gustave Roussy Institute between 2013 and 2023 who received neoadjuvant or first line platinum-based chemotherapy with or without bevacizumab for LGSOC. We assessed overall response rate (ORR) by imaging, biological CA125 response (RUSTIN criteria) and progression free survival (PFS).

Results We identified 29 patients who received neoadjuvant platinum and 9 who received platinum at 1st relapse. Among all evaluable patients (neoadjuvant and 1st relapse setting), the addition of bevacizumab resulted in a statistically significant improvement in ORR (ORR=62% (13/21) for bevacizumab versus 24% (4/17) without bevacizumab; p-value: 0.0247). In the neoadjuvant setting, ORR was 67% in patients with bevacizumab and 27% of patients without bevacizumab. In the relapsed cohort, response rate was 60% with bevacizumab and 25% without bevacizumab. Among 24 patients evaluable according to RUSTIN criteria, the biological ORR to neoadjuvant chemotherapy with bevacizumab was 80% and 50% without bevacizumab. In the relapsed cohort, biological ORR was 100% with or without bevacizumab. Regarding survival, in the neoadjuvant setting, median PFS was 36 months (95% CI 27-NR) with bevacizumab, and 31 months (95% CI 20-NR) with chemotherapy alone. At relapse, median PFS was 16 months (95% CI 11-NR) with bevacizumab and 11 months (95% CI 5.5-NR) with chemotherapy alone.

Conclusion Bevacizumab increases response rate to first line platinum-based chemotherapy both in neoadjuvant and 1st line metastatic/recurrent LGSOC. Our data support the addition of bevacizumab to neoadjuvant platinum in an effort to improve tumor shrinkage and achievement of complete interval cytoreduction.

Disclosures No disclosures.