Pembrolizumab in combination with bevacizumab and oral cyclophosphamide in recurrent platinum-resistant ovarian cancer: A real-world study.

Abstract

e17595 Background: The role of immunotherapy in ovarian cancer remains poorly defined, with limited activity observed for immune checkpoint inhibitors as monotherapy. However, emerging data suggest that combination strategies may enhance efficacy; notably, the addition of pembrolizumab to weekly paclitaxel has recently demonstrated a survival benefit in patients with platinum-resistant disease. We evaluated the efficacy and safety of pembrolizumab combined with bevacizumab and oral cyclophosphamide in patients with recurrent epithelial ovarian cancer. Methods: This retrospective study included all patients with recurrent, platinum-resistant, heavily pre-treated epithelial ovarian cancer who received pembrolizumab in combination with bevacizumab and oral cyclophosphamide at the Oncology Unit of Alexandra University Hospital from January 2021 onward. Clinical characteristics, treatment exposure, and outcomes were extracted from institutional records. Results: Forty-eight patients were included. Median age at diagnosis was 57.9 years (IQR 45.9–63.8). Histology was predominantly high-grade serous ovarian carcinoma (44/48), with two patients each having high-grade endometrioid and clear-cell carcinoma. Most patients (44/48, 91.6%) presented with stage III/IV disease; 32 underwent primary debulking surgery and 11 interval debulking. ECOG performance status was 0–1 in 43 patients, and 7 patients carried BRCA1/2 mutations. Patients were heavily pre-treated, with a median of five prior systemic therapy lines (range 4–9). All patients progressed on first-line platinum-based chemotherapy, with a median progression-free survival (PFS) of 15.0 months (95% CI 9.8–20.1). Patients received a median of four cycles of pembrolizumab–bevacizumab–cyclophosphamide (range 2–35). Overall response rate was 31.3% (15/48), and disease control rate was 45.9% (22/48). Median PFS on pembrolizumab–bevacizumab–cyclophosphamide was 3.7 months (95% CI 2.7–4.8). Twelve patients experienced PFS longer than 6 months; prolonged benefit was not associated with histology, ECOG performance status, BRCA mutation status, or platinum-free interval following first-line therapy. No new safety signals were observed. Conclusions: In a heavily pre-treated, platinum-resistant ovarian cancer population, the combination of pembrolizumab, bevacizumab, and oral cyclophosphamide demonstrated clinically meaningful activity with manageable toxicity. These real-world findings support further exploration of immunotherapy-based combinations in ovarian cancer, particularly in settings where treatment options remain limited.