Oral cyclophosphamide plus bevacizumab in recurrent ovarian, fallopian tube and primary peritoneal cancer.

5517 Background: The combination of bevacizumab, cyclophosphamide and pembrolizumab is NCCN compendium listed based on a phase 2 trial that lacked a comparison arm. The objective of this study was to assess safety and efficacy of bevacizumab plus oral cyclophosphamide in patients with recurrent high-grade ovarian, fallopian tube and primary peritoneal cancer. Methods: This retrospective analysis included patients with recurrent platinum sensitive or resistant high-grade ovarian cancer treated with oral cyclophosphamide plus bevacizumab at a single institution. Treatment consisted of bevacizumab 15 mg/kg intravenously every 3 weeks in combination with oral cyclophosphamide 50 mg daily. Patients with platinum free interval of 6 months or longer were considered to have a platinum sensitive disease. Objective response rate to chemotherapy (ORR = complete response (CR) + partial response (PR)) was calculated with 95% confidence interval (95% CI). Progression free survival (PFS) was calculated from initiation of chemotherapy to earliest date of progression or death and estimated using the methods of Kaplan and Meier. Adverse events were collected and graded using CTCAE v. 5.0. Results: One hundred patients were identified; 14 (14%) were platinum sensitive and 86 (86%) were platinum resistant. Median age was 58 (38-80). The majority of patients had high-grade serous histology (95%) and stage III or IV at diagnosis (95%). The median number of previous treatments was 3 (range 1-9). Thirty-three patients (33%) received bevacizumab in a prior regimen. A median of 5 (range 2-34) cycles of bevacizumab with daily oral cyclophosphamide were administered. ORR was 40.4% (95% CI: 30.7-50.7) with 4% CR, 36% PR, 20% SD, 39% PD. ORR among patients who received bevacizumab in a prior regimen was 12 (36%) compared to ORR of 24 (42%) among patient who never received bevacizumab in a prior regimen (P = 0.59). The median PFS was 4.6 months (95% CI: 3.42-5.9). There was no relationship between platinum status or platinum free interval and response to this regimen, although the population was predominantly platinum resistant. Seventy-six (76%) of patients had documented adverse events. Most common grade 3-4 toxicities included hypertension (3%), thrombocytopenia (3%), and hemorrhagic cystitis (1%). Conclusions: Bevacizumab in combination with oral cyclophosphamide was well tolerated and active, with a response rate of 40% in patients with recurrent platinum resistant high-grade ovarian cancer.