Efficacy and Safety of Ribociclib Combined With AI Versus Physician&Amp;#39;s Choice of Chemotherapy Sequential Endocrine Therapy in ER Middle-low-expression/HER2-negative Advanced Breast Cancer (Rachel)

Inclusion criteria

• Patient is an adult female ≥ 18 years old at the time of informed consent.
• ECGO rating 0-2.
• Histologically confirmed recurrent or metastatic breast cancer, including patients initially diagnosed as stage IV or locally advanced inoperable patients.
• Patient has a histologically and/or cytologically confirmed diagnosis of estrogen-receptor positive and/or progesterone receptor positive breast cancer based on the most recently analyzed tissue sample and all tested by local laboratory. ER should express in the range of 10% to 50%. ER positive by local laboratory testing.
• Patient has HER2-negative breast cancer defined as a negative in situ hybridization test or an IHC status of 0, 1 + or 2 + If IHC is 2 +, a negative in situ hybridization (FISH, CISH, or SISH) test is required by local laboratory testing and based on the most recently analyzed tissue sample.
• Determination by the physician that the patient is in a rapid disease progression situation:
• Symptomatic visceral metastases
• Rapid progression of disease or impending visceral compromise.
• Markedly symptomatic non visceral disease if the treating physician opt to give chemotherapy for rapid palliation of patients symptoms.
• Patient hasn't received systemic anti-cancer therapy at the stage of recurrence/metastasis.
• Patient must have at least one measurable lesion (according to RECIST 1.1 criteria)
• Postmenopausal or pre/perimenopausal female patients are eligible for enrolment; pre or perimenopausal female patients must be willing to receive LHRHa during the study period.
• All patients were required to meet the following laboratory biochemical values prior to enrolment:
• Haematology: Hb ≥90 g/L, WBC ≥3.5×109/L, ANC ≥1.5×109/L, PLT ≥100×109/L;
• Renal function: serum creatinine ≤ upper limit of normal value;
• Liver function: for those without liver metastases, AST, ALT, ALP ≤2.5 times the upper limit of normal values, and ≤1.25 x the upper limit of normal values for total bilirubin; for those with liver metastases, AST, ALT, ALP ≤ 5 times the upper limit of normal value, and total bilirubin ≤ 1.5 x upper limit of normal value.

Exclusion criteria

• Patient has received systemic anti-cancer therapy at the stage of recurrence/metastasis.
• Those who have been treated with CDK4/6 inhibitors in the neoadjuvant/adjuvant phase.
• Patients those with symptomatic CNS metastases.
• Patient has a history of clinically symptomatic cardiovascular, hepatic, respiratory, renal and haemato-endocrine system or neuropsychiatric disorders.
• Patient has a serious concomitant disease, such as an infectious disease; has multiple factors that affect the oral administration and absorption of the drug.
• Pregnant or lactating women (women of childbearing age must have had a negative pregnancy test within 14 days prior to the first dose; if positive, pregnancy must be ruled out by ultrasound).
• Patients in poor general condition who cannot tolerate chemotherapy treatment.
• The investigator considers the patient unsuitable for entry into this study.