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

A Single-arm Clinical Trial of Pirfenidone Plus Sintilimab Combined With Standard Neoadjuvant Chemotherapy for Patients With Colorectal Cancer Peritoneal Metastasis

Assuming that the objective response rate (ORR) of neoadjuvant chemotherapy in patients with colorectal cancer peritoneal metastasis is approximately 0.40 , a total sample size of 30 patients is required.

Step 1:

Ten patients will be initially enrolled. If the number of responders (CR/PR) is < 2, the study will be terminated early for futility.

If the number of responders is > 8, the treatment regimen will be considered effective, and the study may be concluded early.

Step 2:

If the number of responders in Step 1 is between 2 and 8, the study will continue to enroll an additional 20 patients until completion.

Treatment regimen: CapeOX + Pirfenidone + Sintilimab

CapeOX:

Oxaliplatin (L-OHP) 130 mg/m², IV infusion over 2 hours on Day 1 Capecitabine 1,000 mg/m² orally, twice daily for 14 consecutive days Repeated every 3 weeks

Pirfenidone:

Oral administration, 200 mg three times daily, taken on an empty stomach (low-dose regimen)

Sintilimab:

200 mg per dose, IV infusion once every 3 weeks The first 4 cycles are provided free of charge. After the fourth cycle, tumor response will be assessed; if continued use is required, a "buy 2, get 2 free" policy will apply.

Tumor response evaluation will be performed after 4 treatment cycles.

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.