A Single-arm Clinical Study Evaluating Pirfenidone and Sintilimab in Combination With Standard Neoadjuvant Chemotherapy for Colorectal Cancer Patients With Peritoneal Metastasis.

Inclusion Criteria:

1. Age between 18 and 75 years;
2. Radiologically (CT/MRI/PET-CT/FAPI-PET) or pathologically confirmed peritoneal metastasis from colorectal cancer;
3. Planned to receive first-line chemotherapy;
4. ECOG performance status of 0-1;
5. Adequate hematologic, hepatic, and renal function:

   1. Neutrophil count ≥ 1.5 × 10⁹/L
   2. Platelet count ≥ 100 × 10⁹/L
   3. Hemoglobin ≥ 8.0 g/dL
   4. Creatinine clearance \> 30 mL/min
   5. For patients without liver metastasis: AST and ALT ≤ 2.5 × upper limit of normal (ULN)
   6. Total bilirubin ≤ 2 × ULN
   7. APTT and PT ≤ 1.5 × ULN

Exclusion Criteria:

1. Individuals with a tendency to bleed, hereditary bleeding disorders, or evidence of coagulation abnormalities;
2. Pregnant or breastfeeding women, or women of childbearing potential who are not using effective contraception;
3. Expected survival ≤ 3 months;
4. Participation in another investigational drug trial within the past 4 weeks;
5. Prior treatment with any anti-PD-1, anti-PD-L1, anti-PD-L2, or anti-CTLA-4 antibodies (or any other antibodies targeting T-cell co-stimulation or immune checkpoint pathways);
6. Uncontrolled neurological or psychiatric disorders that may affect compliance or the ability to report treatment responses;
7. Known allergy to any study drug.