UPCC 21824 A Randomized, Open-label, Phase 3 Study of Sacituzumab Govitecan Versus Treatment of Physician’s Choice in Participants with Endometrial Cancer Who Have Received Prior Platinum-based Chemotherapy and Anti-PD-1/PD-L1 Immunotherapy (GOG 3104 ASCENT)

Participants must meet all of the following inclusion criteria to be eligible for participation in this
study (no waivers for participant eligibility will be offered or permitted):
1) Participants assigned female at birth, 18 years of age or older (or minimum age according to
country-specific requirements), and able to understand and give written informed consent.
2) Documented evidence of recurrent/persistent endometrial cancer (endometrial carcinoma or
carcinosarcoma).
3) Up to 3 prior lines of systemic therapy for endometrial cancer, including systemic
platinum-based chemotherapy and anti-PD-1/PD-L1 therapy, either in combination or
separately.
• Neoadjuvant and/or adjuvant therapy is considered 1 prior line of systemic therapy.
• Prior monoclonal antibodies or targeted therapies, including but not limited to
bevacizumab, poly (adenosine diphosphate-ribose) polymerase inhibitors, trastuzumab,
will count as a line of treatment if given as a single agent with the intent of controlling
disease. If these agents are given in combination with chemotherapy and continued as
maintenance monotherapy, they will not be counted as a separate line of treatment.
• There is no restriction regarding prior hormonal or hormonal-based therapy. Hormonal or
hormonal-based therapy does not count as a line of therapy.

• For participants who are ineligible for anti-PD-1/PD-L1 therapy due to medical
comorbidities, or if anti-PD-1/PD-L1 agents are not available as standard-of-care therapy
in any line of treatment according to local standards, prior treatment with an
anti-PD-1/PD-L1 agent is not required.
4) Eligible for treatment with either doxorubicin or paclitaxel as determined by the investigator.
Participants must not have any contraindications to receive treatment with doxorubicin or
paclitaxel as per the locally approved product label.
5) Radiologically evaluable disease (either measurable or nonmeasurable) by computed
tomography (CT) or magnetic resonance imaging (MRI) per RECIST v1.1 criteria by
investigator assessment (see Appendix 11.8).
• If a participant has disease based on pleural effusion or ascites alone (with no other
radiologically evaluable lesions), this must be cytologically confirmed.
6) Documented disease progression by CT or MRI during or after the most recent therapy per
RECIST v1.1 criteria by investigator assessment.
7) Availability of tumor tissue from an archival or fresh biopsy for assessment of Trop-2 and
other study biomarkers. Tissue submission should be in the form of a formalin-fixed
paraffin-embedded (FFPE) block (preferably) or ≥ 20 freshly sectioned, unstained slides.
Tissue must be submitted within 4 weeks of randomization (for sites in China,
see Appendix 11.11.1).
• If archival tumor tissue is available, it should preferably be from the most recently
available tumor biopsy (obtained ideally within 12 months prior to randomization), from
a locally recurrent or metastatic site. If archival tissue is not available, a fresh biopsy,
preferably from a locally recurrent or metastatic site should be performed before
randomization. Fine needle aspirates, bone biopsies, and cytology samples are not
suitable samples. If < 20 unstained slides are available, and it is not clinically feasible to
obtain a new biopsy, the participant may still be eligible upon consultation with the
sponsor medical monitor.
8) Eastern Cooperative Oncology Group PS of 0 or 1 

9) Organ function per protocol requirements