A Single-Arm, Phase II Study of Retlirafusp Alfa in Combination With XELOX and Bevacizumab for the First-Line Treatment of Advanced RAS-Mutated Colorectal Cancer With Liver Metastases (CRLM)

Inclusion Criteria: 1. Age: 18-75 years; 2. Unresectable colorectal adenocarcinoma confirmed by histopathology or cytology; 3. MSS/pMMR; 4. RAS-mutant; 5. ECOG PS score of 0-1; 6. No prior systemic treatment; 7. At least one measurable liver metastasis; 8. Expected survival of ≥3 months; 9. Normal function of major organs; no severe abnormalities in hematological, cardiac, pulmonary, hepatic, renal, or bone marrow function; and no immunodeficiency. Laboratory test results must meet the following requirements: ① Hemoglobin (Hb) ≥90 g/L; ② White blood cell (WBC) count ≥ 3.0 × 10⁹/L; neutrophil count (NEUT) ≥ 1.5 × 10⁹/L; ③ Platelet (PLT) count ≥ 100 × 10⁹/L ④ Renal function (serum creatinine, sCr) ≤ 1.5 times the upper limit of normal (ULN); ⑤ Total bilirubin (TBIL) ≤ 1.5 times the upper limit of normal (ULN); 10. Participants voluntarily enroll in this study, sign an informed consent form, demonstrate good compliance, and cooperate with follow-up; 11. The investigator believes the participant may benefit from treatment. Exclusion Criteria: 1. History of or concurrent other malignant tumors, excluding cured basal cell carcinoma of the skin and cervical carcinoma in situ; 2. History of severe cardiovascular disease, such as congestive heart failure (New York Heart Association Class III-IV), myocardial infarction within the past 6 months, unstable angina, or severe arrhythmias; 3. Presence of active infections (e.g., sepsis, active tuberculosis) or uncontrolled autoimmune diseases; 4. History of severe gastrointestinal diseases, such as active peptic ulcers, intestinal obstruction, or gastrointestinal bleeding, which may affect drug absorption or increase treatment-related risks; 5. History of active cirrhosis, uncontrolled comorbidities, chronic myopathy, active hepatitis, or persistent unexplained elevation of serum transaminases; 6. Coagulation disorders with a tendency to bleed (must meet the following criterion 14 days prior to enrollment: INR within the normal range without the use of anticoagulants); Subjects receiving treatment with anticoagulants or vitamin K antagonists, such as warfarin, heparin, or their analogs; low-dose warfarin (1 mg orally once daily) or low-dose aspirin (daily dose not exceeding 100 mg) is permitted for prophylactic purposes, provided that the International Normalized Ratio (INR) of prothrombin time is ≤ 1.5; 7. Allergy to or contraindications for the study drug; 8. Pregnant or breastfeeding women, or patients planning to become pregnant during the study or within 6 months after the study ends and who are not using effective contraception; 9. Presence of other serious, uncontrolled medical conditions or psychiatric disorders that may affect the patient's ability to participate in the study or undergo evaluation; 10. History of thyroid dysfunction, where thyroid function cannot be maintained within the normal range even with medication; 11. Patients with severe, uncontrolled hypertension (systolic blood pressure ≥ 150 mmHg or diastolic blood pressure ≥ 90 mmHg despite antihypertensive medication), or a history of hypertensive crisis or hypertensive encephalopathy; 12. Patients with a history of severe bleeding or a high risk of bleeding, including but not limited to: clinically significant bleeding (e.g., ≥ Grade 2 gastrointestinal bleeding) occurring within 3 months prior to the first administration of the study drug; active hemoptysis (hemoptysis volume ≥ half a teaspoon, approximately 2.5 mL of fresh blood, within the past month); imaging evidence of tumor invasion of major blood vessels; or an untreated coagulation disorder (however, patients receiving a stable dose of anticoagulant therapy with an INR within the therapeutic range may be considered for enrollment following the investigator's assessment); 13. Patients who have experienced the following arterial or venous thromboembolic events within 6 months prior to the first administration of the study drug: cerebrovascular accident (including ischemic stroke and transient ischemic attack), myocardial infarction, acute coronary syndrome, uncontrolled deep vein thrombosis, or pulmonary embolism (superficial venous thrombosis, such as PICC-related upper extremity venous thrombosis, may be considered on a case-by-case basis if assessed by the investigator as low risk); 14. Patients deemed unsuitable for inclusion in this study by the investigator.