Dalpicilib-Enhanced Vs. Standard Endocrine Therapy in ER+ HER2- Early Breast Cancer

Inclusion criteria

• Women aged 18-70 years
• ECOG score of 0-1
• Histologically confirmed unilateral invasive cancer (regardless of pathology type)
• No macroscopic or microscopic tumor residue after surgical resection
• Early-stage breast cancer, pathologically confirmed as ER-positive and HER2-negative (ER-positive defined as immunohistochemical detection of ER >10% of tumor cells positive; HER2 0-1+ or HER2 2+ but FISH negative, with no amplification, defined as HER2-negative)
• Postoperative pathological staging of pT1c or above, N0M0, and meeting one of the following criteria: (1) G3; (2) G2 and meeting one of the following: i. Ki-67 ≥20%; ii. 21-gene recurrence score ≥26 or high genomic risk profile; iii. Age ≤40 years and vascular invasion positive
• No prior neoadjuvant treatment
• Time from surgery or completion of chemotherapy or radiotherapy (whichever occurs later) to randomization does not exceed 8 weeks
• Good postoperative recovery, at least 1 week after surgery
• Normal function of major organs, meeting the following criteria: (1) Hematological criteria: HB ≥90 g/L (no blood transfusion in the last 14 days); ANC ≥1.5 × 10^9 /L; PLT ≥100 × 10^9 /L; (2) Biochemical criteria: TBIL ≤1.5 × ULN (upper limit of normal); ALT and AST ≤3 × ULN; serum Cr ≤1.5 × ULN
• Women of childbearing age must use contraception during treatment
• Subjects voluntarily join this study, sign informed consent, demonstrate good compliance, and cooperate with follow-up

Exclusion criteria

• Bilateral breast cancer or ductal/lobular carcinoma in situ (DCIS/LCIS)
• Received treatment for advanced disease
• Metastasis at any site
• Any tumor > T4a (with skin involvement, fixation, inflammatory breast cancer)
• Clinically or radiologically suspected malignancy in the contralateral breast not confirmed and requiring biopsy
• Received neoadjuvant therapy, including chemotherapy, radiotherapy, and endocrine therapy
• History of malignant tumors within the past 5 years (excluding basal cell carcinoma of the skin and cervical carcinoma in situ), including contralateral breast cancer
• Patient has been enrolled in other clinical trials
• Patient has severe systemic diseases and/or uncontrolled infections that prevent participation in the study
• Severe cardiovascular or cerebrovascular diseases within 6 months prior to randomization (e.g., unstable angina, chronic heart failure, uncontrolled hypertension >150/90 mmHg, myocardial infarction, or stroke)
• Known allergy to relevant medications
• Women of childbearing age who refuse contraception during treatment and for 8 weeks after treatment completion
• Pregnant or breastfeeding women
• Positive pregnancy test before drug administration after joining the trial
• Individuals with mental illness or cognitive impairment who cannot understand the trial protocol and its side effects, unable to comply with the protocol and follow-up (systematic assessment required prior to enrollment)
• Individuals without personal freedom and independent civil capacity