Newton Study (NEW Dosing MainTenance Therapy Ovarian CaNcer)

Inclusion Criteria:

1. 18 years of age or older, female, any race

2. Histologically diagnosed ovarian cancer, fallopian tube cancer or primary peritonealcancer

3. High grade (or grade 3) serous histology or known to have gBRCAmut

4. Has received at least 2 previous lines of platinum-containing therapy (notnecessarily consecutive), and has disease that was considered platinum sensitivefollowing the penultimate platinum line (more than 6-months period betweenpenultimate platinum regimen and progression of disease)

5. Has responded to the last platinum line (PR or CR)

6. No more than 8 weeks have elapsed from completion of the last platinum regimen andthe patient is still not progressing after response

7. Eastern Cooperative Oncology Group (ECOG) performance status of ≤ 1

8. Adequate bone marrow, kidney and liver function, defined as follows:

9. Absolute neutrophil count ≥ 1,500/µL

10. Platelets ≥ 100,000/µL

11. Hemoglobin ≥ 9 g/dL

12. Serum creatinine ≤ 1.5 x upper limit of normal (ULN) or calculated creatinineclearance ≥ 30 mL/min using the Cockcroft-Gault equation

13. Total bilirubin ≤ 1.5 x ULN (≤2.0 in patients with known Gilberts syndrome) ORdirect bilirubin ≤ 1 x ULN

14. Aspartate aminotransferase and alanine aminotransferase ≤ 2.5 x ULN unlessliver metastases are present, in which case they must be ≤ 5 x ULN

15. Patient receiving corticosteroids may continue as long as their dose is stable forleast 4 weeks prior to initiating protocol therapy.

16. Patient must have a negative urine or serum pregnancy test within 7 days prior totaking study treatment if childbearing potential and agrees to abstain fromactivities that could result in pregnancy from screening through 180 days after thelast dose of study treatment or use adequate barrier methods throughout the study.Non-childbearing potential is defined as follows (by other than medical reasons): ≥45 years of age and has not had menses for >1 year; patients with amenorrhea for <2years without history of a hysterectomy and oophorectomy must have a folliclestimulating hormone value in the postmenopausal range upon screening evaluation;Post-hysterectomy, post-bilateral oophorectomy, or post-tubal ligation. Documentedhysterectomy or oophorectomy must be confirmed with medical records of the actualprocedure or confirmed by an ultrasound. Tubal ligation must be confirmed withmedical records, otherwise the patient must be willing to use 2 adequate barriermethods throughout the study, starting with the screening visit through 180 daysafter the last dose of study treatment.

17. Patient must agree to not breastfeed during the study or for 180 days after the lastdose of study treatment.

18. Patient must be able to understand the study procedures and agree to participate inthe study by providing written informed consent.

19. Patients must have normal blood pressure or adequately treated and controlledhypertension. (i.e. systolic BP ≤ 140 mmHg and diastolic BP ≤ 90 mmHg)

Exclusion Criteria:

1. Patient simultaneously enrolled in any interventional clinical trial

2. Invasive cancer other than ovarian cancer within 2 years (except basal or squamouscell carcinoma of the skin that has been definitely treated)

3. Patient with known, symptomatic brain or leptomeningeal metastases

4. Patient with immunocompromised status

5. Patient with known active hepatic disease

6. Prior treatment with a known PARP inhibitor

7. Patient who has had major surgery ≤ 3 weeks prior to initiating protocol therapy andparticipant must have recovered from any surgical effects.

8. Patient who has received investigational therapy ≤ 4 weeks, or within a timeinterval less than at least 5 half-lives of the investigational agent, whichever isshorter, prior initiating protocol therapy.

9. Patient has had radiation therapy encompassing >20% of the bone marrow within 2weeks prior to day 1 of protocol therapy

10. Patient has had any radiation therapy within 1 week prior to day 1 of protocoltherapy.

11. Patient with known hypersensitivity to niraparib components or excipients.

12. Patient has received a transfusion (platelets or red blood cells) ≤ 4 weeks prior toinitiating protocol therapy.

13. Patient has received colony stimulating factors (e.g., granulocytecolony-stimulating factor, granulocyte macrophage colony stimulating factor, orrecombinant erythropoietin) within 4 weeks prior initiating protocol therapy.

14. Patient has had any known Grade 3 or 4 anemia, neutropenia or thrombocytopenia dueto prior chemotherapy that persisted > 4 weeks and was related to the most recenttreatment.

15. Patient with any known history of myelodysplastic syndrome (MDS) or acute myeloidleukemia (AML)

16. Patient with a serious, uncontrolled medical disorder. Examples include, but are notlimited to, nonmalignant systemic disease, active, uncontrolled infection,uncontrolled ventricular arrhythmia, recent (within 90 days) myocardial infarction,uncontrolled major seizure disorder, unstable spinal cord compression, superior venacava syndrome, or any psychiatric disorder that prohibits obtaining informed consent