FMT+ QL1706+Bevacizumab+ XELOX as First-line Treatment for Advanced MSS-type Colorectal Cancer With Liver Metastasis

Inclusion Criteria: 1. Histological or cytological confirmed advanced colorectal cancer with liver metastasis. 2. Signed written informed consent. 3. Have not received anti-tumor treatment. 4. According to the investigators assessment, at least one measurable target lesion defined by RECIST v1.1. 5. Patients of both sexes, aged ≥18 years and ≤75 years. 6. ECOG PS 0-1; 7. Expected survival time ≥ 3 months; 8. Have adequate organ and bone marrow function, laboratory examination within 7 days prior to enrollment meets the following requirements, as follows: 1\) Blood routine: ANC ≥ 1.5 × 10\^9/L, Platelet count ≥ 100 × 10\^9/L, HGB ≥100 g/L (no blood transfusion or erythropoietin dependence within 14 days); 2) Liver function: TBIL ≤1.5 x ULN; ALT/AST ≤ 5 x ULN; ALP ≤5×ULN; 3) Renal function: Cr ≤1.5×ULN, or creatinine clearance ≥50 mL/min: Urine routine results showed urinary protein \< 2+; 4) Coagulation function: INR or PT ≤1.5 x ULN. 9.For female subjects of reproductive age, a urine or serum pregnancy test should be performed and the result is negative 3 days prior to receiving the initial study drug administration. 10\. For women of childbearing potential (WOCBP): agreement to refrain from heterosexual intercourse or use contraception. 11\. For men: agreement to refrain from heterosexual intercourse or use a condom, and agreement to refrain from donating sperm. Exclusion Criteria: 1. Suffered from other malignancies in the past 5 years, excluding cured basal cell carcinoma of the skin, cervical carcinoma in situ and papillary thyroid carcinoma. 2. Patients requiring elective surgery during the trial. 3. Patients who cannot take oral drugs, or have conditions that the investigator determines to significantly affect gastrointestinal absorption, such as chronic diarrhea, intestinal obstruction, etc., and are not suitable for treatment. 4. Patients during pregnancy (positive pregnancy test) or lactation. 5. Central nervous system metastasis or meningeal metastasis. 6. Uncontrollable bone metastasis, or patients at risk of fracture, requiring surgery, local radiation therapy. 7. Patients with active infection requiring systemic anti-infection treatment. 8. Patients with a history of immunodeficiency, including those who are positive for HIV antibody tests. 9. Patients with known, active autoimmune diseases. 10. Patients with uncontrolled active hepatitis B, patients with hepatitis C virus infection (HCV antibody positive). 11. A history of severe cardiovascular and cerebrovascular diseases, including but not limited to: severe arrhythmia, acute coronary syndrome within 6 months, congestive heart failure, aortic dissection, stroke, and T IA history. 12. Severe bleeding events occur within half a year, or high bleeding risk factors such as active digestive tract ulcers and esophageal and gastric varices due to liver cirrhosis. 13. Patients with diabetes who cannot be stably controlled by drugs (including insulin). 14. Mental or language disorders that prevent communication with the patient; 15. Patients participating in another clinical trial. 16. MSI-H/ d MMR without immunotherapy; left colorectum of Ras, Raf wild-type. 17. The investigator believes that the subject has other serious systemic diseases or other conditions that make him unsuitable for participation in this trial.