Efficacy of Platinum-based Chemotherapy in Platinum-resistant Ovarian Cancer) (EPITOC)

Inclusion Criteria: * Age 18-70 years; * Histologically confirmed epithelial ovarian cancer (excluding mucinous, clear-cell and low-grade subtypes); * Ovarian cancer recurrence within 3-6 months after completion of platinum-based chemotherapy (given to possible variability in follow-up practices and tumor growth kinetics patients with platinum-free interval ≥3 and \<7 months will be considered platinum-resistant); * Platinum-free interval ≤12 months; * Eastern Cooperative Oncology Group (ECOG) performance status ≤2; * Response to penultimate platinum-based chemotherapy defined as partial or complete response assessed by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria or ≥50% reduction in CA-125 concentration for patients without measurable lesions; * Not refractory to penultimate platinum-based chemotherapy regimen (ie, the disease did not progress during platinum-based chemotherapy and within ≤3 months after its completion); * Patients received ≤3 lines of prior chemotherapy; * No central nervous system (CNS) metastatic involvement; * No severe and uncontrolled concomitant diseases; * Adequate organ function: * Bone marrow - hemoglobin ≥ 90 g/l; Neutrophils ≥1,5x109/l; Platelets ≥75x109/l); * Renal - estimated creatinine clearance ≥50 ml/min (determined by Cockcroft-Gault equation); * Hepatic - alanine aminotransferase (ALaT) \& aspartate transaminase (ASaT) ≤3 upper limit of normal (ULN), total bilirubin ≤ 25 umol/l; * Known BRCA1/2 mutation status as it will be used for stratification; * Life expectancy \>3 months; * Patient is willingly consent to participate in the trial and signed informed consent form Exclusion Criteria: * Platinum-refractory ovarian cancer defined as disease progression during penultimate platinum-based chemotherapy or ≤3 month after its completion; * No response to penultimate platinum-based chemotherapy; * Mucinous, clear-cell or low-grade serous/endometrioid histology; * \>3 lines of prior therapy lines for advanced ovarian cancer (prior maintenance endocrine therapy or poly ADP ribose polymerase (PARP) inhibitors is allowed); * Prior therapy with PARP-inhibitors and endocrine therapy as a treatment for progressive ovarian cancer; * Platinum-free interval \>12 months; * Symptoms of bowel obstruction of any etiology; * Contraindications to platinum-based chemotherapy; * Planned administration of PARP inhibitors during or after this line of chemotherapy; * Life expectancy \<3 months; * Uncontrolled and/or severe concomitant diseases (eg, uncontrolled diabetes mellitus, renal failure, hepatic failure, uncontrolled arterial hypertension, arrhythmia, heart failure); * Metastatic CNS involvement; * Neuropathy grade \>2.