Inclusion Criteria:

          -  Male or female subject >= 18 years

          -  Histologically/cytologically confirmed, locally advanced unresectable or metastatic
             breast cancer or gastric cancer.

          -  ECOG score 0 or 1

          -  Life expectancy >3 months

          -  According to the definition of RECIST1.1, the patient has at least one measurable
             lesion

          -  Adequate organ function prior to start treatment with KN026

          -  Able to understand, voluntarily participate and willing to sign the ICF

          -  Subjects (women of child-bearing potential and males with fertile female partner) must
             be willing to use viable contraception method.

        Exclusion Criteria:

          -  Accepted any other anti-tumor drug therapies within 4 weeks before fist dose

          -  Accepted radiotherapy within 4 weeks before enrollment

          -  An anthracyclines antibiotic treatment was received exceeding 300 mg/m² within 90 days
             before first KN026 dosing, or other equivalent dose antharcyclines

          -  Subjects are eligible with clinically controlled and stable neurologic function >= 4
             weeks, which is no evidence of CNS disease progression; Subjects with spinal cord
             compression and cancerous meningitis are not eligible

          -  Pregnant or nursing females；or intend pregnancy within this study period or within 6
             monthes after the end of this study

          -  History of immunodeficiency, including HIV positive or other acquired, congenital
             immunodeficiency disease, or a history of organ transplantation

          -  Severe chronic and active infection, need to system antibiosis/antiviral treatment

          -  Cavity effusion (pleural effusion, ascites, pericardial effusion, etc.) are not well
             controlled, and need locally treatment or repeated drainage