Background: The combination of cediranib (ced) and olaparib (olap) improves progression-free survival and overall response rates (ORR) in women with recurrent plat sensitive high-grade serous (HGS) ovca compared to olap alone. However, the activity of this combination in plat resistant disease has not been characterized and biomarkers of response are poorly understood. We conducted a Phase 2 study to assess the activity of ced/olap in plat resistant ovca and to identify biomarkers of response (NCT02345265). Methods: Patients (pts) across 11 centers were enrolled to two cohorts (plat sensitive or resistant ovca). All pts received ced 30mg daily and olap tablets 200mg BID. Eligibility included pts with recurrent HGS or BRCA-related ovca. Pts had measurable disease by RECIST 1.1, the ability to take POs, available archival tissue, and biopsiable disease. No prior anti-angiogenics in the recurrent setting or prior PARP inhibitor was allowed. All pts underwent mandatory pre-treatment and on-treatment biopsies and had the option of undergoing a post-progression biopsy. Results: 72 pts were enrolled, with 70 pts receiving treatment (35 plat sensitive and 35 plat resistant). The ORR in plat sensitive pts was 77% (90%CI 63-88%), with 3 confirmed CRs and 24 confirmed PRs. 22 of 27 responders remain progression free with a median follow-up of 7 months. Ten of the plat sensitive responders had a germline BRCA mutation, 8 were wild type, and 9 had not been tested. Disease control rate (DCR; SD at 16wks + CR + PR) was 91%. The ORR in plat resistant pts was 20% (90% CI 11-38%) with 7 confirmed PRs. Median duration of response was 6 months and DCR 43% in plat resistant patients. Among the 7 pts with confirmed response in the plat resistant cohort, 3 had germline BRCA mutation, 3 were wild type, and 1 had not been tested. Conclusions: Ced/olap demonstrated clinical activity in women with recurrent plat sensitive and plat resistant ovarian cancer. While the presence of germline BRCA mutation was correlated with increased likelihood of response, confirmed responses were observed in BRCA wild type pts with plat resistant disease. Molecular studies are ongoing to investigate additional predictive biomarkers. Clinical trial information: NCT02345265