• Are female adults (defined as ≥18 years of age or acceptable age according to local regulations at the time of voluntarily giving informed consent).

• Have histologically confirmed endometrial cancer that:

‣ Is recurrent,

⁃ Has a HER2 IHC score of 1+, 2+, or 3+ as determined by central laboratory testing for HER2 protein expression, and

⁃ Is not defined as a true sarcoma (i.e., leiomyosarcoma or endometrial stromal sarcoma). Note: Uterine carcinosarcoma is allowed.

• Have measurable disease defined by RECIST 1.1.

• Have Eastern Cooperative Oncology Group (ECOG) Performance Status of 0, 1 or 2.

• Have had at least one prior line of platinum-based therapy (in any setting). Up to three lines of prior therapy are allowed. Prior hormonal therapy and radiation are allowed and do not count as prior lines of therapy. Platinum-based chemotherapy and ICI may have been given together or in separate lines of therapy.

• Have a life expectancy of ≥12 weeks at screening.