• Female patients ≥ 18 years of age

• Histologically-confirmed LGSOC (ovarian, peritoneal) by tissue biopsy read by pathology at study institution. NOTE: Patients with a prior history of serous borderline tumors without prior systemic (cytotoxic or hormonal) treatment but a new diagnosis of low-grade serous ovarian cancer are eligible.

• Determination that the patient is not a primary surgical candidate by a gynecologic oncologist surgeon; or has undergone an attempted primary debulking with residual RECIST measurable disease.

• Measurable disease according to RECIST 1.1. Measurable disease is defined as at least one lesion that can be accurately measured in at least one dimension. Each lesion must be ≥10mm when measured by CT or MRI. Lymph nodes must be ≥15mm by short axis when measured by CT or MRI.

• An Eastern Cooperative Group (ECOG) performance status of ≤1. Patients with an ECOG performance status of 2 are permitted on trial if this is deemed to be secondary to cancer but not to other comorbidities.

• Patients with treated brain metastases are eligible if follow-up brain imaging after CNS-directed therapy shows no evidence of progression. Patients with asymptomatic brain metastases that do not require intervention are also eligible.

• HIV-infected patients on effective anti-retroviral therapy with undetectable viral load within 6 months are eligible for this trial.

• For patients with evidence of chronic hepatitis B virus (HBV) infection, the HBV viral load must be undetectable on suppressive therapy, if indicated.

• Patients with a history of hepatitis C virus (HCV) infection must have been treated and cured. For patients with HCV infection who are currently on anti-HCV treatment, they are eligible if they have an undetectable HCV viral load.

• Patients with a prior or concurrent malignancy whose natural history or treatment does not have the potential to interfere with the safety or efficacy assessment of the investigational regimen are eligible for this trial.

• Female patients with reproductive potential agree to use highly effective method of contraceptive during the trial and for 1 month following the last dose of study intervention, unless surgical menopause is conferred. Women of child-bearing potential must have a negative pregnancy test within 14 days prior to commencement of study treatment. Non-hormonal methods of highly effective contraception include:

‣ intrauterine device (IUD)

⁃ bilateral tubal occlusion

⁃ vasectomized partner

⁃ sexual abstinence

• Patients must have adequate cardiac function with left ventricular ejection fraction ≥ 50% by echocardiography (ECHO) or multiple-gated acquisition (MUGA) scan.

• Baseline QTc interval \< 460 ms (Common Terminology Criteria for Adverse Events \[CTCAE\] Grade 1) using Fredericia's QT correction formula. NOTE: This criterion does not apply to patients with a right or left bundle branch block.

• Adequate organ function, defined by the following parameters:

• °Adequate hematologic function

• Hemoglobin \[Hb\] ≥ 9.0 g/dL. If a red blood cell transfusion has been administered the Hb must remain stable and ≥ 9.0 g/dL for at least 1 week prior to first dose of study intervention.

• Platelets ≥ 100,000/mm\^3

• Absolute neutrophil count \[ANC\] ≥ 1000/mm\^3

• °Adequate hepatic function:

• Total bilirubin ≤1.5 × upper limit of normal \[ULN\] for the institution; patients with Gilbert syndrome may enroll if total bilirubin is \<3.0mg/dL (51 μmole/L) upon discussion with MSK PI.

• Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 2.5 × ULN (or \<5 xULN in patients with liver metastases).

‣ Adequate renal function with creatinine clearance rate of ≥50 mL/min as calculated by the Cockcroft-Gault formula or serum creatinine of ≤ 1.5 x ULN.

⁃ Creatine phosphokinase (CPK) ≤2.5 x ULN.