This Phase II is trying to understand safe and effective a new cancer drug (ZN-c3) is in people with recurrent or persistent uterine serous carcinomaA Phase 2 Open-Label, Multicenter Study to Evaluate Efficacy and Safety of ZN-c3 in Adult Women With Recurrent or Persistent Uterine Serous Carcinoma

Inclusion

1. Females ≥18 years of age at the time of informed consent.

2. Histologically confirmed recurrent or persistent USC for which no other proven effective treatment options are available or any available standard of care therapy was not tolerated or was refused by the subject.

   • Subjects with endometrial carcinoma of mixed histology where the serous component comprises at least 5% of the tumor will be considered eligible.
   • Subjects with carcinosarcomas (even if there is a serous component) are not eligible.
3. Measurable disease per RECIST Guideline Version 1.1

4. Required prior therapy for endometrial cancer:

   1. Treatment with a platinum-based chemotherapy regimen.
   2. Treatment with a PD-(L)1 inhibitor
   3. Known HER2-positive tumors: Treatment with at least 1 HER2-targeted therapy, except for subjects who are not clinically eligible.
5. Adequate hematologic and organ function