Main Inclusion Criteria:

          -  Females with histologically confirmed recurrent, advanced or metastatic endometrial
             carcinoma

          -  Eligible patients should have progressed on or after first line platinum-based
             chemotherapy for advanced/metastatic endometrial cancer. Patients who have had two or
             more lines of chemotherapy for advanced/metastatic disease are not eligible, taking
             into account the following:

               -  Patients may have received up to one additional line of chemotherapy if given in
                  the neoadjuvant or adjuvant setting. If such treatment was completed less than 6
                  months prior to the current tumor recurrence or progression it is to be
                  considered first-line treatment;

               -  No more than one line of non-cytotoxic systemic cancer therapy (such as
                  immunotherapy, trastuzumab or protein kinase inhibitors) is allowed.

          -  HER2 tumor expression defined as a 1+, 2+ or 3+ score on IHC or positive by ISH

          -  At least one measurable cancer lesion as defined by the Response Evaluation Criteria
             for Solid Tumours (RECIST version 1.1);

          -  Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2;

        Exclusion Criteria:

          -  Current or previous use of a prohibited medication as listed in the protocol;

          -  History of infusion-related reactions and/or hypersensitivity to trastuzumab;

          -  History of keratitis;

          -  Severe, uncontrolled systemic disease at screening;

          -  Left Ventricular Ejection Fraction (LVEF) < 50%, or a history of clinically
             significant decrease in LVEF during previous treatment with trastuzumab;

          -  History of clinically significant cardiovascular disease;

          -  Symptomatic brain metastases, brain metastases requiring steroids to manage symptoms,
             or treatment for brain metastases within 8 weeks prior to randomization;

          -  History or presence of idiopathic pulmonary fibrosis, organizing pneumonia (e.g.
             bronchiolitis obliterans), drug-induced pneumonitis, idiopathic pneumonitis, or
             evidence of active pneumonitis on screening chest computed tomography (CT) scan.