Trial of KN026 in Patients With HER2-positive Advanced Malignant Breast Cancer and Gastric Cancer

Inclusion Criteria: * Male or female subject \>= 18 years and =\<75 years. * Histologically or 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(Subjects are eligible, which accepted palliative therapies within 2 weeks before the first dose of KN026 for osseous metastatic and all the AEs recovered). * An anthracyclines antibiotic treatment, such as doxorubicin (Adriamycin) 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. * Has not recovered (ie, \>Grade 1) from AEs except alopecia and anemia. * 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. -