Background: BNC105P is a tubulin polymerization inhibitor and a vascular disrupting agent (VDA). In vivo exposure to BNC105P leads to selective damage of tumor vasculature in both primary and metastatic lesions, causing disruption of blood flow to tumors, hypoxia, and associated tumor necrosis. BNC105P also has a direct anti-proliferative action on cancer cells, including ovarian cancer cell lines. Pre-clinical data has demonstrated synergistic activity of BNC105P when combined with platinum or with gemcitabine, supporting the proposed study design. This study will determine the safety and efficacy of BNC105P in ovarian cancer when used in combination with gemcitabine-carboplatin. The target population is women with ovarian or primary peritoneal cancers who progressed 4 to 9 months after first-line platinum based chemotherapy, or 4 to 12 months after second line platinum based chemotherapy. Methods: A single arm phase I will be used to determine the phase II dose for the triplet combination (3-6 subjects per dose level, maximum of 24 subjects). Four dose levels of BNC105P (12-16 mg/m²) and gemcitabine (800-1000 mg/m²) will be assessed. The dose of carboplatin will be set at AUC 4. Enrolment to cohort 2 started in January 2013. The phase II component will consist of a 2-arm, randomized (1:1) study of BNC105P, gemcitabine and carboplatin versus gemcitabine and carboplatin alone. The primary endpoint for the phase II trial is objective response rate (ORR, according to RECIST 1.1 and/or GCIG CA125 criteria. An ORR of 40% or more with the experimental regimen would be considered worthy of further investigation, assuming an ORR of 20% with the control regimen. 110 phase II participants are planned (N = 55/arm). Treatment allocation will be balanced using minimization for the study site, target lesions according to RECIST (present vs. absent), progression free interval from last platinum based chemotherapy regimen (<6 months vs 6 months or more), and first relapse vs. second relapse. Biomarker (tissue and blood-borne) sampling and PK analysis will also be undertaken. Clinical trial information: NCT01624493.