The Aim of This Study is to Assess the Efficacy and Safety of Chidamide, Regorafenib in Combination With Iparomlimab and Tuvonralimab for the Treatment of Advanced Colorectal Cancer in Third-line Therapy and Subsequent Lines.

Inclusion criteria

• Patients with advanced colorectal adenocarcinoma confirmed by histology or cytology;
• Those who have experienced disease progression or are intolerant to treatment after receiving ≥ 2 lines of systemic standard therapy;
• Patients must have at least one measurable lesion (according to RECIST 1.1 criteria);
• Patients who have received local radiotherapy at least 3 weeks before the first drug treatment are eligible for inclusion; however, the lesions evaluated by RECIST must not be within the radiotherapy field;
• Patients must be at least 18 years old;
• Performance status ECOG score of 0-1;
• Expected survival ≥ 12 weeks;
• Patients must have the ability to understand and voluntarily sign the written informed consent form;
• Women of childbearing age must have a negative pregnancy test within 7 days before the start of treatment. During the study period, both the patient and the patient's spouse must take contraceptive measures.

Exclusion criteria

• Patients who have undergone major surgery or suffered severe trauma within 4 weeks prior to the first dose of the study drug;
• Patients with hypersensitivity to any component of the study protocol;
• Patients planning to conceive or who are pregnant;
• Patients with brain metastases and an inability to accurately describe their condition;
• Patients who have experienced any of the following diseases within 6 months prior to the start of the study treatment: myocardial infarction, severe/unstable angina pectoris, NYHA class 2 or higher congestive heart failure, uncontrolled arrhythmia, etc.;
• Abnormal laboratory tests:

Absolute neutrophil count (ANC) < 1,500/mm3; Platelet count < 75,000/mm3; Total bilirubin > 1.5 times the upper limit of normal; Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) > 2.5 times the upper limit of normal (for patients with liver metastases > 5 times the upper limit of normal); Creatinine > 1.5 times the upper limit of normal;

• Patients who have had other cancers (except advanced colorectal cancer) within 5 years prior to the start of this study treatment. Cervical carcinoma in situ, cured basal cell carcinoma and bladder epithelial tumors are excluded;
• Patients with a history of drug abuse, drug addiction, or alcohol dependence;
• Patients without legal capacity or with limited civil capacity;
• Other conditions that the investigator deems inappropriate for inclusion in the study.