PULSAR Combined With PD-1 Ab and Chemotherapy Plus Bev. for CRLM

Inclusion Criteria: 1. Age 18-75 years, any gender. 2. Pathologically confirmed colorectal adenocarcinoma with liver metastases from colorectal cancer. 3. Eastern Cooperative Oncology Group (ECOG) performance status 0-1. 4. Adequate organ function, no contraindications to radiotherapy, or immunotherapy. 5. Estimated life expectancy of more than 3 months. 6. No obvious indications for emergent surgery due to primary tumor bleeding, obstruction, or similar conditions. 7. At least one radiographically measurable lesion per Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. 8. Microsatellite/mismatch repair status MSS/pMMR. 9. No prior anti-tumor therapy for colorectal cancer, including radiotherapy, chemotherapy, or surgery. 10. No prior immunotherapy. 11. Women of childbearing potential or men with partners of childbearing potential agree to use highly effective contraception (annual failure rate \<1%) from 7 days before the first dose through 24 weeks after the last dose. 12. Ability and willingness to comply with study visits, treatment schedules, laboratory testing, and other protocol-specified procedures throughout the study. 13. Signed written informed consent. Exclusion Criteria: 1. Pregnant or lactating women. 2. Pathological diagnosis of signet ring cell carcinoma. 3. History of other malignancies within the past 5 years, except cured skin cancer and cervical carcinoma in situ. 4. Uncontrolled epilepsy, central nervous system disorders, or history of psychiatric disorders that, in the opinion of the investigator, may interfere with signing the informed consent form or affect patient compliance with oral medication. 5. Clinically significant (i.e., active) cardiac disease, such as symptomatic coronary artery disease, New York Heart Association (NYHA) Class II or greater congestive heart failure, or significant arrhythmias requiring drug intervention (see Appendix 12), or history of myocardial infarction within the past 12 months. 6. Organ transplant recipients requiring immunosuppressive therapy and long-term steroid users. 7. Patients with autoimmune diseases. 8. Severe uncontrolled recurrent infections or other severe uncontrolled comorbidities. 9. Subjects with baseline hematological and biochemical parameters not meeting the following criteria: hemoglobin ≥90g/L; absolute neutrophil count (ANC) .≥1.5×10\^9/L; platelets ≥100×10\^9/L; ALT, AST ≤2.5 times the upper limit of normal; ALP ≤2.5 times the upper limit of normal; serum total bilirubin \<1.5 times the upper limit of normal; serum creatinine \<1 times the upper limit of normal; serum albumin ≥30g/L. 10. Known deficiency of dihydropyrimidine dehydrogenase (DPD). 11. Allergy to any investigational drug components.