A Study of Azenosertib (ZN-c3) in Subjects With Platinum-Resistant High-Grade Serous Ovarian, Fallopian Tube or Primary Peritoneal Cancer

Inclusion Criteria:

1. Age ≥18 years

2. High-grade serous ovarian, fallopian tube or primary peritoneal cancer

3. Tumor testing (archival acceptable) confirms a positive Cyclin E1 protein statusresult determined by IHC using the Sponsor's investigational clinical trial assay

4. Prior therapy:

5. Subjects must have platinum-resistant disease

6. One to 3 prior lines or regimens are allowed (1 to 4 prior lines are permitted,if prior mirvetuximab)

7. Prior bevacizumab treatment is required, if eligible per standard of care

8. Prior PARP inhibitor treatment is required if BRCA 1/2 mutation or HRD, ifeligible per standard of care

9. Prior mirvetuximab treatment is required, if eligible per standard of care

10. Measurable disease per RECIST Version 1.1.

11. Adequate hematologic and organ function, as defined in protocol

12. ECOG 0-1

Exclusion Criteria:

1. Primary platinum-refractory disease

2. Any of the following treatment interventions within the specified time frame priorto C1D1:

3. Major surgery within 28 days

4. Hospitalization within 14 days

5. Any chemotherapy or targeted tumor therapy within 21 days or 5 half-lives (whichever is shorter);

6. Radiation therapy within 21 days;

7. Autologous or allogeneic stem cell transplant within 3 months.

8. Current use of any other investigational drug therapy <28 days or 5 half-lives (whichever is shorter).

9. Inability to discontinue treatment prescription or non-prescription drugs, orto discontinue consumption of food and herbal supplements that are strong ormoderate CYP3A inhibitors and inducers or P-gp inhibitors at least 14 daysprior to C1D1.

10. Prior therapy with ZN-c3 or any other WEE1 inhibitor, ATR inhibitor, PKMYT1inhibitor, or CHK1/2 inhibitor.

11. A serious illness or medical condition(s) including, but not limited to:

12. Clinically or radiographically unstable brain metastases or leptomeningealdisease that requires immediate treatment. Subjects with asymptomatic brainmetastases are eligible.

13. Myocardial impairment resulting in heart failure (NYHA Class II-IV)

14. Severe acute or chronic medical or psychiatric condition or laboratoryabnormality that may increase risk associated with study participation or mayinterfere with interpretation of study results

15. Acute kidney injury requiring intervention or intravenous fluid in the last 14days or presence of indwelling urinary catheter or percutaneous nephrostomy.

16. Significant gastrointestinal abnormalities, including an inability to take oralmedication, requirement for intravenous alimentation, active peptic ulcer,chronic diarrhea or vomiting considered to be clinically significant in thejudgment of the Investigator, or prior surgical procedures affectingabsorption.

17. Active, uncontrolled infection. Subjects with an infection receiving treatment (antibiotic, antifungal, or antiviral) must have completed such treatment andthe infection must be considered controlled/resolved (and afebrile) by theInvestigator for at least 7 days before C1D1

18. Any evidence of bowel obstruction as determined by air/fluid levels on computedtomography (CT scan, recent hospitalization for small bowel obstruction within 3 months prior to C1D1, or recurrent paracentesis or thoracentesis within 6weeks prior to C1D1.

19. Unresolved toxicity of Grade >1 attributed to any prior therapies (excluding Grade ≤2 neuropathy, alopecia, or skin pigmentation).

20. Pregnant or lactating female subject or female subject of childbearing potential whohas a positive serum pregnancy test within 14 days prior to C1D1.

21. History of another malignancy in the previous 2 years, unless cured by surgery aloneand continuously disease free. Exceptions include appropriately treated carcinoma insitu of the cervix, non-melanoma skin carcinoma, Stage 1 uterine cancer, or othermalignancies with an expected curative outcome.

22. Subjects who are known to be immunocompromised or HIV-positive on highly activeanti-retroviral therapy.

23. Subjects with known active hepatitis B or hepatitis C infection.

24. Individuals who are judged by the Investigator to be unsuitable as study subjects.

25. Subjects who had prior wide-field radiotherapy affecting ≥ 20% of the bone marrow.