A Study of MR001 in Patients With Locally Recurrent or Metastatic Advanced Triple-Negative Breast Cancer (TNBC)

Inclusion Criteria: * Patients with histologically or cytologically confirmed triple-negative breast cancer (TNBC). * Subjects with locally recurrent or metastatic advanced TNBC who have progressed after first-line or later-line therapy. * Presence of at least one measurable lesion according to RECIST V1.1 criteria. * ECOG Performance Status 0 or 1. * Life expectancy \>3 months. * Adequate organ and hematopoietic function based on the laboratory tests. * Voluntarily sign the informed consent form. Exclusion Criteria: * History of severe allergy or hypersensitivity to the investigational product or its excipients or drugs of similar chemical class (e.g., monoclonal antibodies), or contraindications to the investigational product. * Requirement for systemic immunosuppressive therapy within 14 days prior to the first dose of study drug or during the study. * Major surgery (excluding puncture biopsy) within 4 weeks prior to the first dose of study drug, or anticipated need for major surgery during this study. * Uncontrolled active brain metastases or leptomeningeal metastasis. * History of autoimmune disease requiring treatment with corticosteroids or immunosuppressive drugs. * Women in the period of preconception, pregnancy, or lactation. * Any other circumstances which the investigator considers may increase risks to subjects or interfere with the results of the trial.