Combination Followed by Maintenance Chemotherapy Versus CDK4/6 Inhibitor Combined With Endocrine Therapy for HR Low/HER2-negative Advanced Breast Cancer: a Prospective, Randomized, Open-label Phase Ⅱ Clinical Trial

Exclusion Criteria11

• symptomatic, uncontrolled brain or leptomeningeal metastases; Patients who had received previous systemic radical treatment for brain metastases (radiotherapy or surgery), if stable disease had been maintained for at least 1 month as confirmed by imaging, and if systemic hormone therapy (dose 10mg/ day prednisone or other effective hormones) for more than 2 weeks without clinical symptoms.
• patients received radiotherapy, chemotherapy, major surgery, targeted therapy or immunotherapy within 2 weeks before enrollment; Patients received endocrine therapy within 1 week before enrollment. Chemotherapy with nitrosourea or mitomycin was administered within 6 weeks before enrollment.
• participated in other clinical trials of new drugs within 4 weeks before enrollment;
• there can not be controlled by drainage or pneumatic methods third space effusion;
• patients with other malignant tumors within the past 3 years, excluding radical cervical carcinoma in situ, skin basal cell carcinoma or skin squamous cell carcinoma;
• suffering from serious or uncontrolled diseases, including but not limited to: 1) active viral infection, such as HIV or HBV active (HbsAg positive and HBV-DNA≥103, hepatitis C antibody positive); 2) history of severe cardiovascular disease: uncontrolled hypertension; Myocardial infarction, unstable arrhythmia, congestive heart failure, pericarditis, myocarditis, etc. Patients with NYHA class ⅲ-ⅳ cardiac dysfunction, or left ventricular ejection fraction (LVEF) 50% by echocardiography; 3) severe infection (e.g., intravenous antibiotic, antifungal, or antiviral therapy according to clinical practice) within 4 weeks prior to the first dose or unexplained fever during screening/before the first dose; 38.3°C (fever due to cancer, as judged by the investigator, was eligible);
• patients with a history of psychotropic drug abuse and unable to abstain or with mental disorders; Or accompanied by swallowing and absorption dysfunction;
• patients with other concomitant diseases that seriously endanger the safety of patients or affect the completion of the study according to the judgment of the investigators;
• patients with known history of allergy to the components of this regimen; A history of immunodeficiency, including testing positive for HIV, HCV or other acquired or congenital immunodeficiency disorders, or a history of organ transplantation;
• pregnant or lactating women;
• Patients deemed unsuitable for inclusion by the investigators.