Dalpiciclib Plus Toremifene for First-line Advanced HR Positive and HER2 Negative Breast Cancer

Experimental population:Advanced first-line HR+, HER2 metastatic breast cancer patients Research endpoint: Main research endpoint: PFS evaluated by researchers (according to RECIST 1.1 standard) Secondary study endpoint: ORR、CBR、DCR、OS The incidence of adverse events (AE) and severe adverse events (SAE) Exploratory study endpoint: Tumor infiltrating lymphocytes (sTIL) Peripheral blood lymphocyte ratio Distribution of fecal microbiota Research overall design:This study adopts a prospective, single arm design, and plans to include 36 postmenopausal or premenopausal/perimenopausal patients with metastatic breast cancer who are HR positive and HER2 negative, and receive maintenance treatment with darcy plus toremifene. In this study, the screening period did not exceed 28 days. After completing the screening examination and evaluation, eligible subjects entered the study treatment period and received maintenance treatment with darcilib combined with toremifen, for a period of 4 weeks until disease progression, intolerable toxicity, withdrawal of informed consent, or termination of medication as determined by the investigator. Conduct research according to the plan regulations Treatment and visits. Perform tumor imaging evaluation every 2 cycles (8 weeks ± 7 days) during the first 13 treatment cycles (52 weeks) of the treatment period; Afterwards, tumor imaging evaluation will be conducted every 3 cycles (12 weeks ± 7 days). Subjects should visit the research center at the end of treatment/withdrawal from the study to complete corresponding safety checks and imaging evaluations; And visit the research center 28 days after the last treatment to complete the corresponding safety assessment.