Efficacy and Safety of KN026 in Combination With HB1801 in the First-line Treatment of Subjects With HER2-positive Recurrent or Metastatic Breast Cancer.

The purpose of this study is to assess the efficacy and safety of KN026 combined with HB1801 versus trastuzumab combined with pertuzumab and docetaxel as first-line treatment for HER2-positive recurrent or metastatic breast cancer. This study will establish an independent data monitoring committee (IDMC) to conduct safety assessments after approximately 20 subjects in the treatment group complete the first cycle of treatment. During the safety assessment period, the study will continue to enroll subjects, and safety review meetings will be at 1 year of randomization in the first subject. In addition, the IDMC plans to conduct one interim analysis of efficacy during the study period. The primary study hypotheses are that the combination of KN026 combined with HB1801 is superior to trastuzumab combined with pertuzumab and docetaxel with respect to: Progression-free Survival (PFS) as assessed by the BIRC per Response Evaluation Criteria in Solid Tumors (RECIST 1.1).