Pembrolizumab in Combination with Bevacizumab and Oral Cyclophosphamide in Heavily Pretreated Platinum-Resistant Ovarian Cancer

Abstract Background: Immune checkpoint inhibitors (ICIs) have been widely implemented in the treatment of solid tumors. Although epithelial ovarian carcinoma is considered as scarcely immunogenic, the presence of tumor-infiltrating T lymphocytes (TILs) in the ovarian tumor microenvironment (TME) could increase sensitivity to immune checkpoint inhibitors (ICIs). Combinations of ICIs with chemotherapy, anti-VEGF compounds and PARP inhibitors are under evaluation in ovarian cancer. Recently, a Phase II study evaluated the efficacy of Pembrolizumab in Combination with bevacizumab and oral cyclophosphamide in patients with recurrent platinum-sensitive, platinum-resistant, or refractory epithelial ovarian cancer. Methods: Herein, we present a retrospective study of all patients who received pembrolizumab in combination with bevacizumab and oral cyclophosphamide for recurrent platinum-resistant heavily pretreated ovarian cancer in the Oncology Unit of Alexandra University Hospital. Results: Median age at diagnosis was 54.5 years (SD; 8.9; range: 44–72). All patients were diagnosed with high-grade serous ovarian carcinoma (HGSC). Initial disease stage was FIGO IIIC (8/10; 80%), IIIB (1/10; 10%) and IIC (1/10; 10%)). Patients were heavily pretreated with a median of 6 (range: 4–9) prior lines of systemic therapy. All patients have experienced disease progression on first-line platinum-based chemotherapy and median PFS to first-line treatment was 20.1 months (95%CI; 11.4 – 28.7). Patients received a median of 4 cycles of pembrolizumab in combination with cyclophosphamide and bevacizumab (range 2-11). ORR was 20% (2/10) with two patients achieving partial response (PR) and two patients achieving stable disease (SD) while disease control rate (DCR) was 40% (4/10). Median PFS was 2.7 months (95%; 0.6 – 4.8) and 6-month PFS rate 20%. Conclusions: Though our data reflect a small population, we here demonstrate that the combination of pembrolizumab with bevacizumab and oral cyclophosphamide is an effective alternative in platinum-resistant recurrent ovarian carcinoma. This novel combination provides a promising alternative in heavily pretreated patients that have otherwise limited treatment options.