The purpose of this study is to evaluate the safety and efficacy of SYD985 in recurrent, advanced or metastatic endometrial cancer.

This is an open-label, single-arm study in patients with HER2-expressing recurrent, advanced or metastatic endometrial carcinoma. HER2-expression is defined as a 1+, 2+ or 3+ score on immunohistochemistry (IHC) or positive by in situ hybridization (ISH). Eligible patients for this study should have progressed on or after first line platinum-based chemotherapy. Patients who have had two or more lines of chemotherapy for advanced/metastatic disease are not eligible.

Eligible patients will receive SYD985 until disease progression or unacceptable toxicity. Patients who have stopped study treatment for other reasons than disease progression will continue their tumor evaluations in an observation period until disease progression or start of a new anticancer therapy.

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.