Inclusion Criteria:

• Has a histologically-confirmed diagnosis of endometrial carcinoma or carcinosarcoma.
• Has radiographically evaluable disease, either measurable or nonmeasurable per response evaluation criteria in solid tumors (RECIST 1.1), as assessed by blinded independent central review (BICR).
• Has received prior platinum-based chemotherapy and anti-programmed cell death 1 protein (PD-1)/anti- programmed cell death ligand 1 (PD-L1) therapy, either separately or in combination.

Exclusion Criteria:

• Has neuroendocrine tumors or endometrial sarcoma, including stromal sarcoma, leiomyosarcoma, adenosarcoma, or other types of pure sarcomas.
• Has a history of documented severe dry eye syndrome, severe Meibomian gland disease and/or blepharitis, or corneal disease that prevents/delays corneal healing.
• Has active inflammatory bowel disease requiring immunosuppressive medication or previous history of inflammatory bowel disease.
• Has had a recurrence of endometrial carcinoma or carcinosarcoma more than 180 days after completing platinum-based therapy administered in the curative-intent or adjuvant setting without any additional platinum-based therapy received in the metastatic or recurrent setting.
• Has received more than 3 prior lines of therapy for endometrial carcinoma or carcinosarcoma.

• FIGO 2009 stage IA-IVB non-recurrent, chemo-naive, HER2-positive endometrial serous carcinoma or carcinosarcoma
• Measurable or no-measurable disease allowed
• ECOG PS 0-2
• No prior chemo, biologic therapy, or targeted thearpy for treatment of endometrial cancer
• No prior radiation therapy for endometrial cancer
• No planned radiation
• No significant cardiac, lung, or intercurrent illness
• Patients with prior treatment with hormonal therapy are allowed