Study of KN026 Monotherapy or Combination Therapy in Patients With Metastatic Breast Cancer

Inclusion Criteria:

• Male or female subject >= 18 years
• Histologically/cytologically confirmed, locally advanced unresectable or metastaticbreast cancer
• ECOG score 0 or 1
• Life expectancy >3 months
• According to the definition of RECIST1.1, the patient has at least one measurablelesion
• Adequate organ function prior to start treatment with KN026
• Able to understand, voluntarily participate and willing to sign the ICF

Exclusion Criteria:

• Accepted any other anti-tumor drug therapies within 4 weeks before fist dose
• Accepted radiotherapy within 4 weeks before enrollment
• Subjects are eligible with clinically controlled and stable neurologic function >= 4weeks, which is no evidence of CNS disease progression; Subjects with spinal cordcompression and cancerous meningitis are not eligible
• Pregnant or nursing females；or intend pregnancy within this study period or within 6monthes after the end of this study
• History of immunodeficiency, including HIV positive or other acquired, congenitalimmunodeficiency disease, or a history of organ transplantation
• History of immunodeficiency, including HIV positive or other acquired, congenitalimmunodeficiency disease, or a history of organ transplantation
• Cavity effusion (pleural effusion, ascites, pericardial effusion, etc.) are not wellcontrolled, and need locally treatment or repeated drainage