This is a non-inferiority study to examine Trastuzumab combined with chemotherapy or endocrine therapy in patients with metastatic Luminal B2 breast cancer subtype. The main purposes of this study are to test the safety and clinical benefit of Trastuzumab combined with chemotherapy or endocrine therapy in treating Luminal B2 breast cancer (hormone receptor positive and human epidermal growth factor receptor (HER2) positive or amplification). This multicentre, randomized study is designed to recruit up to 392 subjects to identify 196 research subjects for each study treatment.
The primary objective of this study is to compare progression-free survival (PFS) of patients with metastatic Luminal B2 breast cancer subtype randomised to treatment with Trastuzumab Combined With Chemotherapy or Endocrine Therapy.