Inclusion Criteria:
1. Histological or cytological-based diagnosis of high grade and low grade epithelial ovarian cancer. Patients with clear cell ovarian cancers are not eligible to participate in this study due to higher risk of thromboemboli which could be increased by Tamoxifen.
2. Platinum resistant ovarian cancer with no more than 4 lines of previous systemic therapy (re-treatment with a previous regimen is only counted as 1 line of therapy).
3. Age \> 18 years.
4. Patient must be willing and able to comply with scheduled visits, treatment plan, laboratory tests and other study procedures
5. Eastern Cooperative Oncology Group Performance Status of 0 or 1
6. Adequate hematologic and organ function within 14 days before the first study treatment on Day 1 of Cycle 1, defined by the following:
* Neutrophils (absolute neutrophil count ANC \>1.5X10\^9/L,)
* Hemoglobin \>9 g/dL
* Platelet count \>100,000/L
* Serum albumin \>3 g/dL
* Total bilirubin 1.5 ≤the upper limit of normal (ULN) and AST and ALT ≤2.5 XULN, with the following exception:
* Patients with known Gilbert syndrome who have serum bilirubin ≤3XULN may be enrolled.
* Patients with documented liver metastasis may have AST and ALT ≤5XULN
* PTT (or aPTT) and INR ≤1.5XULN (except for patients receiving anticoagulation therapy)
* Serum creatinine ≤ 1.5XULN or creatinine clearance \>50 mL/min based on Cockcroft-Gault glomerular filtration rate estimation: (140 - age) X(weight in kg) X0.85 (if female) 72 X(serum creatinine in mg/dL)
7. Life expectancy of at least 3 months
8. Have at least 1 measurable lesion assessable using standard techniques by RECIST v1.1. Patients without any measurable disease may be enrolled on a case-by-case basis in discussion with study principle investigator
9. At least 4 weeks washout period from previous line of treatment (including hormonal treatment) , 2 weeks from radiotherapy
10. Ability to swallow and retain oral medications (without crushing, dissolving or chewing tablets)
11. Willing and able to comply with all study requirements, including treatment (e.g. able to swallow tablets), timing and/or nature of required assessments
Exclusion Criteria:
1. Patients with any other prior malignancy from which the patient has been disease free for less than 3 years, with the exception of adequately treated and cured basal or squamous cell skin cancer, superficial bladder cancer, carcinoma in situ of any site or any other cancer as approved by study principle investigator
2. Uncontrolled intercurrent illness including, but not limited to ongoing or active infection, symptomatic or asymptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements.
3. History of or current evidence of HIV infection, Viral hepatitis (e.g., positive for hepatitis B surface antigen \[HBsAg\] or hepatitis C virus \[HCV\] antibody at screening)
4. Patients with symptomatic central nervous system (CNS) metastasis and/or carcinomatous meningitis. Patients with treated CNS metastases are eligible for this study if not receiving corticosteroids and/or anticonvulsants for at least 7 days prior to first dose of study treatment, and the disease is asymptomatic and radiographically stable for at least 2 weeks after completion of CNS-directed therapy. Patients with untreated stable or asymptomatic brain metastases may be enrolled on a case-by-case basis in discussion with study principal investigator.
5. Patients with existing or past history of deep venous thromboembolism are excluded, unless stable on anticoagulation.
6. Patients with Khorana score of greater than or equal to 3 (see https://www.mdcalc.com/khorana-risk-score-venousthromboembolism- cancer-patients)
7. Known hypersensitivity or contraindication to any component of the study treatment.
8. Inability to comply with study and follow-up procedures.
9. Patients who have not recovered (≤ grade 2) from adverse events related to previous treatments, unless approved by study principle investigator
10. Patients unable to swallow orally administered medications and patients with gastrointestinal impairment that could affect the ability to take or absorption of oral medications including sub-acute or complete bowel obstruction.
11. Participants with uncontrolled intercurrent illness
12. Participants not recovered from all toxicities related to prior anticancer therapies to CTCAE grade\<1 apart from alopecia
13. Patients with psychiatric illness/social situations that would limit compliance with study requirements
