Safety and Efficacy Study of Nuc-1031 and Carboplatin Combination to Treat Recurrent Ovarian Cancer

Inclusion Criteria: * Provision of signed written informed consent. * Original diagnosis and/or histological confirmation of relapsed epithelial ovarian, fallopian tube or primary peritoneal cancer. * Relapse ≤24 months from completion of platinum (carboplatin or cisplatin) or platinum-containing regimen. * Age ≥ 18 years. * Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1 or 2. * Measurable disease as defined by Response Evaluation Criteria In Solid Tumours (RECIST) criteria version 1.1; January 2009 and/or evaluable disease (evaluable: cytologically or radiologically detectable disease such as ascites, peritoneal deposits, or lesions which do not fulfill RECIST criteria version 1.1 for measurable disease) \[1,2\]. Participants for whom disease and response to therapy can be monitored by serum Cancer Antigen 125 (CA125) levels will also be eligible. * Adequate bone marrow function as defined by: White Blood Cells of ≥ 3 x109/L, Absolute Neutrophil Count (ANC) of ≥ 2.0 x 109/L, platelet count of ≥ 100.0 x 109/L, and haemoglobin of ≥ 9 g/dL. * Adequate liver function, as determined by: Serum total bilirubin ≤1.5 x Upper Limit of Normal \[(ULN), Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) ≤ 2.5 x ULN, albumin ≥ 30g/L. * Adequate renal function assessed as glomerular filtration rate(GFR) ≥ 60 mL/min using Cr51-ethylenediaminetetraacetic acid (EDTA) method. * Ability to comply with protocol requirements. * Participants must be postmenopausal (12 months of amenorrhea), surgically sterile or they must agree to use a physical method of contraception. Oral or injectable contraceptive agents cannot be the sole method of contraception. Participants of child-bearing potential must have a negative serum pregnancy test within seven days prior to the first study drug administration. Exclusion Criteria: * History of allergic reactions attributed to previous gemcitabine treatment. * Previous treatment with Nuc-1031. * History of allergic reactions attributed to previous carboplatin treatment. * Symptomatic Central Nervous System (CNS) or leptomeningeal metastases. * Prior chemotherapy, radiotherapy (other than short cycle of palliative radiotherapy for bone pain), or immunotherapy within 28 days of first receipt of study drug (within 6 weeks for nitrosoureas and mitomycin C). Hormone therapy within 14 days of first receipt of study drug. * Prior toxicities from chemotherapy or radiotherapy which have not regressed to Grade ≤ 1 severity \[National Cancer Institute -Common Terminology Criteria for Adverse Events, (NCI-CTCAE) version 4.03\] except for neuropathy and alopecia. * Another active cancer (excluding basal cell carcinoma) within the last 3 years. * Participants with uncontrolled concomitant illness or active infection requiring IV antibiotics. * Participants with serious illnesses, medical conditions, or other medical history, including laboratory results, which, in the investigator's opinion, would be likely to interfere with a their participation in the study, or with the interpretation of the results. * Known Human Immunodeficiency Virus (HIV) or known active Hepatitis B or C. * Any condition (e.g., known or suspected poor compliance, psychological instability, geographical location, etc.) that, in the judgment of the investigator, may affect the participant's ability to sign the informed consent and undergo study procedures. * Currently pregnant, lactating or breastfeeding