Background: PARP-inhibitors and anti-angiogenic agents are active substances against ovarian cancer (OC). We investigated the safety, tolerability and Recommended Phase 2 Dose (RP2D) of the combination of niraparib, a PARP-inhibitor, and bevacizumab. NCT02354131 Methods: This single-arm study enrolled patients with platinum-sensitive high-grade serous/endometrioid OC. Any number of previous chemotherapy courses was permitted. In 3+3 design the patients received fixed dose bevacizumab (15mg/kg iv q 21 days) with dose escalation of niraparib (100, 200, 300mg oral, daily). Prior anti-angiogenic therapy was permitted. The primary objectives were to determine the maximum tolerated dose (MTD) and dose-limiting toxicities (DLTs) of the bevacizumab-niraparib combination therapy and to decide the RP2D of this combination. Results: 12 patients (3+3+6) were enrolled to three dose levels. 3 patients had gBRCA2 mutation, while others were gBRCAwt. Common related toxicities at cycle 1 were hypertension (G3 = 5), anaemia (G3 = 3), thrombocytopenia (G3 = 1), fatigue (G2 = 1), constipation (G2 = 1), and nausea (G2 = 1). One DLT (Grade 3 thrombocytopenia that persisted for ≥ 5 days) was observed at the highest dose level (bevacizumab 15 mg/kg iv q 21 days; niraparib 300mg daily). The RP2D is bevacizumab 15 mg/kg iv q 21 days with niraparib 300mg daily. Niraparib dose reductions were needed in 4 pts (cohort 2 = 1; cohort 3 = 3), bevacizumab dose interruptions in 2 pts. First patient entered study on April 20, 2015. Median number of cycles delivered to date is 48. Ten patients are continuing treatment while 2 pts have ended treatment (1PD; 1 withdrawal of consent). Disease control rate is 91%, response rate 45% (1CR, 4PR). Conclusions: Bevacizumab-niraparib combination has hematologic DLT and manageable class toxicities. This combination has preliminary evidence of efficacy. A phase 2 randomized trial is on-going (AVANOVA2). Clinical trial information: NCT02354131