YL202 Versus Treatment of Physician's Choice in Patients With HR+/HER2- Breast Cancer

Inclusion criteria

• Have been informed of the study before the start of the study and voluntarily sign name and date on the informed consent form.
• Histologically and/or cytologically confirmed locally advanced or metastatic HR+/HER2- breast cancer who are not candidates for curative surgery or radiotherapy.
• Patients who had failed at least one line of systemic chemotherapy in unresectable locally advanced, recurrent, or metastatic stage.
• Have at least 1 extracranial measurable lesion as a target lesion per RECIST 1.1.
• Tumor tissue samples can be provided at the time of diagnosis of locally advanced or metastatic tumors.
• Eastern Cooperative Oncology Group (ECOG) performance status score of 0 to 1.
• Have Adequate organ and bone marrow function within 7 days prior to the first dose.
• Female patients of childbearing potential must agree to use highly effective contraception from screening throughout the duration of the study and for at least 6 months after the last dose of study drug.
• Have a expected survival ≥ 3 months.
• Have ability and willingness to comply with protocol-specified visits and procedures.

Exclusion criteria

• Have prior treatment with an agent targeting HER3.
• Have prior treatment with topoisomerase I inhibitor or an ADC that consists of topoisomerase I inhibitor.
• Have insufficient washout period for prior anticancer therapy prior to first dose of the study drug.
• Have major surgery (excluding diagnostic surgery) within 4 weeks prior to the first dose of study drug or anticipation of major surgery during the study.
• Leptomeningeal metastases or carcinomatous meningitis, spinal cord compression.
• Have uncontrolled or clinically significant cardiovascular and cerebrovascular disease.
• Have clinically significant concomitant pulmonary diseases.
• Have uncontrolled pleural effusion, abdominal effusion.
• Have serious infection within 4 weeks prior to the first dose.
• Have a history of severe hypersensitivity reactions to the drug substance, inactive ingredients in the drug product, or other monoclonal antibodies.