• Participant must be able to give signed, written informed consent.

• Participant must have histologically documented, high-grade endometrial cancer.

• Treatment History Requirements:

∙ Subject must have received prior platinum-based chemotherapy

‣ Subject must have received prior anti-PD-(L)1 therapy

• Participant must have histologically confirmed metastatic cancer that has progressed during or after at least 1 prior therapeutic regimen.

• Participant must have at least 1 measurable lesion per RECIST v1.1 criteria (by local Investigator) in a baseline tumor imaging that has been obtained within 28 days of the treatment start. Participant must have radiographic evidence of disease progression based on RECIST v1.1 criteria following the most recent line of treatment.

• Arm 1 and 2 only: Participant must be willing to provide tissue from a newly obtained tumor biopsy from an accessible tumor lesion not previously irradiated after written informed consent.

• Newly obtained is defined as a specimen taken after written informed consent is obtained, during the 28-day Screening period.

• Participant must be willing to provide an archival tumor tissue block or at least 20 unstained slides, if available.

• Participant must have stabilized or recovered (Grade 1 or baseline) from all prior therapy related toxicities, except as follows:

∙ Alopecia is accepted.

‣ Endocrine events from prior immunotherapy stabilized at ≤ Grade 2 due to need for replacement therapy are accepted (including hypothyroidism, diabetes mellitus, or adrenal insufficiency).

‣ Neuropathy events from prior cytotoxic therapies stabilized at ≤ Grade 2 are accepted.

• Participant must have an Eastern Cooperative Oncology Group Performance Status 0 or 1.

⁃ Participant must have an estimated life expectancy of longer than 3 months.

⁃ Participant must have adequate organ function at Screening, defined as:

• Absolute neutrophil count \> 1500 cells/µL without growth factor support within 1 week prior to obtaining the hematology values at Screening.

∙ Hemoglobin ≥ 9.0 g/dL.

∙ Platelets ≥ 150,000 cells/µL without transfusion within 1 week prior to obtaining the hematology values at Screening.

∙ Calculated creatinine clearance (CrCl) ≥ 50 mL/min as calculated by the Cockcroft-Gault formula.

∙ Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 3 × upper limit of normal (ULN); ≤ 5 × ULN if liver metastases are present.

∙ Total bilirubin ≤ 1.5 × ULN not associated with Gilbert's syndrome. If associated with Gilbert's syndrome ≤ 3 x ULN is acceptable.

∙ Serum albumin ≥ 3 g/dL.

⁃ Participant must have adequate coagulation profile as defined below if not on anticoagulation. If subject is receiving anticoagulation therapy, then subject must be on a stable dose of anticoagulation for ≥ 1 month:

• Prothrombin time within 1.5 x ULN.

∙ Activated partial thromboplastin time within 1.5 x ULN.