mFOLFOX6 Combined With Dalpiciclib in Patients With Metastatic Colorectal Cancer

Inclusion Criteria: * Subjects voluntarily sign informed consent * Age: from 18 to 70 years old * Definite histological evidence of colorectal adenocarcinoma * ECOG 0-1 * Advanced or metastatic colorectal cancer (AJCC/UICC stage IV) is confirmed by enhanced CT of the chest, abdomen and pelvis, with evaluable lesions * Tumor progression or intolerable toxicity after previous standard treatment; Tumor progression during adjuvant therapy or within 6 months after completion of adjuvant therapy was considered as first-line treatment (Standard treatment must include all of the following drugs: fluorouracil, irinotecan, and oxaliplatin; With or without anti-VEGF monoclonal antibody (bevacizumab); Anti-EGFR treatment(cetuximab or panitumumab) in left colorectal RAS (KRAS/NRAS) wild-type subjects) * The bone marrow, liver and kidney function satisfies the following conditions within 7 days before treatment (including day 7): Hemoglobin ≥90g/L, neutrophil count ≥1.5×109/L, platelet count ≥75×109/L; aspartate aminotransferase (AST) ≤ 2 upper limit of normal (ULN), glutaminate alanine transaminase (ALT) ≤ 3 ULN, total bilirubin ≤ 1.5 ULN, serum creatinine ≤ 1.5 ULN * Peripheral neurological lesions recover (≤ grade 1) before enrollment * Subjects should not participate in other clinical trials during the study period * Willing and able to comply with research procedures and follow-up plan Exclusion Criteria: * Complicated with obstruction, active bleeding or perforation and requiring emergency surgery or stent placement * Existing or coexisting other active malignancies * Previously CDK inhibitors treatment * Major surgery or severe trauma such as laparotomy, thoracotomy or laparoscopic organ removal within the previous 4 weeks * Active coronary artery disease, severe/unstable angina or newly diagnosed angina or myocardial infarction in the past 12 months * Thrombotic or embolic events occurred within the previous 6 months, such as cerebrovascular accident (including transient ischemic attack), pulmonary embolism or deep vein thrombosis * New York Heart Association (NYHA) Class II or higher Congestive heart failure * Presence of clinically symptomatic third space effusion (eg, massive pleural or ascites) that cannot be controlled by drainage or other methods * Human immunodeficiency virus (HIV) infection or diseases associated with acquired immunodeficiency syndrome (AIDS) * Active inflammatory bowel disease or other colorectal disease leading to chronic diarrhea * Presence of CTCAE grade 2 or higher toxicity (other than anemia, alopecia and skin pigmentation) that has not recover due to any previous treatment * Suspected allergies to any of the relevant drugs used in the study * Pregnant or lactating * Women of childbearing age (\<2 years after last menstrual period) or men of childbearing potential not using or refusing to use effective non-hormonal contraception * Any unstable medical condition that affects patient safety and study compliance