The study is to assess the safety, efficacy and pharmacokinetic Behavior of Leuprolide Injectable Emulsion for Premenopausal Breast Cancer Subjects.

This is a multicenter, randomized, open-Label , non-inferiority phase III study . All premenopausal women breast cancer subjects were randomly allocated to either the study group or control group in a 1:1 ratio. Furthermore, all subjects received tamoxifen citrate treatment throughout the entire duration of the study. The efficacy of maintaining serum E2 levels ≤30 pg/mL at 4-48 weeks post-treatment will be assessed in both groups.

Inclusion Criteria:

• Premenopausal female subjects aged 18 to 55 years old.
• Histological or cytological confirmation of HR+，HER2- premenopausal breast cancer.
• Subjects have any breast cancer surgery before informing, and no clinical residual local regional lesions were found after the surgery.
• Life expectancy is not less than 12 weeks.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
• Adequate function of major organs.

Exclusion Criteria:

• History of evidence of distant metastatic lesions;
• Subjects have the history of new adjuvant or adjuvant endocrine treatment for breast cancer ( Excluding subjects receiving tamoxifen citrate tablets treatment for less than 12 weeks before informing).
• Active hepatitis B, hepatitis C or HIV in screening.