"Thymalfasin Immunotherapy Study with Triple Regimen in Advanced MSS/pMMR Colorectal Cancer"

Inclusion Criteria:

• Able to sign a written informed consent form (ICF) and able to understand and complywith the requirements of this study Male or female aged 18 to 75 Histologically orcytologically confirmed advanced or metastatic colorectal adenocarcinoma Mismatchrepair (MMR) protein expression or microsatellite instability (MSI) testing showingpMMR/MSS ECOG score of 0 or 1 At least one measurable lesion per iRECIST Expectedsurvival of ≥ 3 months Disease progression or intolerance after at least second-linestandard systemic therapy

Normal major organ function and hematological parameters (within 14 days prior to randomization):

Hematology tests must meet the following criteria:

WBCs≥2.0×10^9/L NEUT≥1.5×10^9/L Hb≥90g/L (9.0g/dL); PLT ≥100×10^9/L;

Biochemistry tests must meet the following criteria:

TBIL ≤ 1.5 × upper limit of normal (ULN); Without liver metastases, ALT or AST ≤ 3.0 ULN; with liver metastases, ALT or AST ≤ 5 ULN; Serum albumin level ≥ 30 g/L Serum Cr ≤ 1.5 ULN, with an endogenous creatinine clearance (CrCl) > 40 mL/min (using Cockcroft-Gault formula) For females: CrCl =((140-Age）×Weight（kg）× 0.85)/(72 × Cr (mg/dL)) For males: CrCl =((140-Age）×Weight（kg）× 1.00)/(72 × Cr (mg/dL)) Urine protein < 2+; if urine protein ≥ 2+, 24-hour urine protein must be < 1 g Prothrombin time or activated partial thromboplastin time and international normalized ratio ≤ 1.5 × ULN Able to swallow and absorb oral medication Females of childbearing potential must use appropriate contraceptive methods during the study and for 6 months after the last dose of the study drug. For males, they should be surgically sterilized or agree to use appropriate contraceptive methods during the study and for 6 months after the last dose of the study drug.

Exclusion Criteria:

1. Previous treatment with Regorafenib, PD-1, PD-L1, or CTLA-4 inhibitors, or anyform of immunotherapy; 2. Treatment with related drugs or medical technologyaffecting immunity within 6 months prior to the first dose of the study drug (including but not limited to: thymopentin, interferon, tumor vaccines, CAR-Ttherapy, etc.); 3. Receiving any study drug, radiotherapy, or major surgerywithin 28 days prior to the first dose of the study drug; 4. Receiving anyanti-tumor treatment (chemotherapy, targeted therapy, etc.) within 3 weeksprior to the first dose of the study drug; 5. Presence of symptomatic centralnervous system (CNS) metastases or CNS metastases requiring local CNS-directedtherapy (such as radiotherapy or surgery). Exceptions include those previouslytreated and stable for ≥ 2 months and who have stopped systemic treatment formore than 4 weeks prior to the first dose of the study drug; 6. Known allergyor intolerance to any of the study drugs or their components; 7. Pregnant orlactating females; 8. History of other malignant tumors within the past 5 years (excluding carcinoma in situ or basal cell or squamous cell skin cancer;subjects with other malignant tumors who have been cured for at least 5 yearsare eligible); 9. Symptomatic congestive heart failure (NYHA Class II-IV),symptomatic or uncontrolled arrhythmias; 10. Poorly controlled hypertension,defined as systolic blood pressure ≥ 150 mmHg or diastolic blood pressure ≥ 100mmHg despite best medical treatment; 11. Unstable angina (angina symptoms atrest), new onset angina (within the past 3 months), or myocardial infarctionwithin 6 months prior to the first dose of the study drug; 12. Major thromboticor bleeding events within 6 months prior to randomization (includinghemoptysis, gastrointestinal bleeding, hematemesis, central nervous system (CNS) bleeding, severe epistaxis or vaginal bleeding, cerebral infarction,transient ischemic attack, or uncontrolled coronary heart disease). Orrequiring lifelong oral anticoagulant therapy; 13. With active, known, orsuspected autoimmune diseases; 14. Receiving immunosuppressive agents within 4weeks prior to the first dose of the study drug, excluding topicalglucocorticoids or physiological doses of systemic glucocorticoids administeredby nasal, inhalation, or other routes (i.e., no more than 10 mg prednisoloneper day or equivalent dosage of other glucocorticoids); 15. Diagnosed withimmunodeficiency or on chronic systemic steroid therapy (at a dose in excess of 10 mg prednisone equivalent per day) or any other form of immunosuppressivetherapy; 16. History of interstitial lung disease; 17. Active tuberculosisrequiring anti-tuberculosis treatment or treatment for tuberculosis within 1year prior to the first dose of the study drug; 18. Acute or chronic activehepatitis B or hepatitis C; 19. Known history of human immunodeficiency virus (HIV) or syphilis infection; 20. Other active or severe infections requiringsystemic antibacterial, antifungal, or antiviral treatment within 4 weeks priorto the first dose of the study drug; 21. Unresolved clinical toxicity ≥ Grade 2 (NCI-CTCAE, v5.0) due to prior anti-tumor treatment, excluding alopecia ornon-clinically significant laboratory abnormalities; 22. Intestinalobstruction, gastrointestinal perforation, Crohn's disease, ulcerative colitis,abdominal abscess, chronic diarrhea, or fistula disease within 6 months priorto enrollment; 23. Hepatic encephalopathy, hepatorenal syndrome, or Child-Pughclass B or more severe cirrhosis; 24. Vaccination with live vaccines within 30days prior to planned initiation of the study drug (seasonal influenza vaccineswithout live virus are permitted); 25. History of alcohol abuse or drug abuse;
2. Other acute or chronic diseases, psychiatric disorders, or laboratoryabnormalities that the investigator believes would make the use of the studydrug unfavorable or affect the interpretation of AEs, or, in the investigator'sjudgment, would result in inadequate compliance during the study period.