Phase II Investigation of Pembrolizumab in Combination With Bevacizumab and Oral Cyclophosphamide in Patients With High Grade Ovarian Cancer and Surgically Documented Minimal Residual Disease After Frontline Therapy

Primary Objectives 1\. To determine whether the combination of pembrolizumab, bevacizumab (or equivalent biosimilars) and oral low dose cyclophosphamide can improve PFS by 6 months (compared to historical control/current trial) in patients with high grade ovarian cancer with residual disease identified by second look laparoscopy. Secondary Objectives 1\. To determine the safety of the above regimen in this patient population. Exploratory Objectives 1. Correlating clinical benefit with gene expression and immune profiles of tumor tissue from SLL and confirmatory biopsy at the time of radiological progression. 2. Tumor cell free tumor DNA (ctDNA) is emerging as a potentially sensitive marker of response in patients undergoing immunotherapy treatment(Lee et al. 2018). We will compare serial plasma ctDNA levels with response by RECIST v1.1.