Objective: To explore the curative effect and safty of Changchun Ruibin metronomic chemotherapy combined with endistat in the treatment of HR positive HER2 negative advanced breast carcinoma.

Only participants who meet all of the following eligibility criteria will be eligible for this trial:

• Age ≥ 18 years;
• Patients with advanced breast carcinoma confirmed by histopathological and / or cytological examination;
• HER2-negative breast carcinoma with confirmed HR positive primary and / or metastatic lesions;
• At least one evaluable tumor lesion (according to RECIST1.1);
• Prior 2-4 lines of therapy, which must include one endocrine therapy with CDK4 / 6 inhibitors, one chemotherapy with paclitaxel.
• Previous 1L of ADC drug therapy is acceptable.
• Complete clinical data on important research indicators;
• The Eastern Oncology Assistance Group (ECOG) physical fitness status score was 0-2;
• Life expectancy > 6 months.