Evaluation of the Efficacy and Safety of Interleucin-2 Combined With PD-1 Monoclonal Antibody and CAPOX in Preoperative Neoadjuvant Therapy for Mid-low Locally Advanced Rectal Cancer - a Single-center, Single-arm, Open-label Clinical Trail

Inclusion Criteria:

1. Males and females aged between 18 and 75 years;
2. ECOG performance status score of 0 or 1;
3. Histologically confirmed rectal adenocarcinoma;
4. Clinical stage T3-T4 or any T with positive lymph nodes (N+): locally advanced;
5. Microsatellite stable (MSS) or deficient mismatch repair (dMMR) status;
6. Distance from the anal verge ≤ 12 cm;
7. Adequate hematologic, hepatic, and renal function.

Exclusion Criteria:

1. Metastatic disease (Stage IV); recurrent colorectal cancer with active bleeding, perforation, or complex conditions requiring urgent surgery; or concurrent presence of other non-colorectal malignancies;
2. Patients who have previously received systemic anticancer therapy for colorectal cancer; or patients treated with PD-1, PD-L1, or CTLA-4 antibodies;
3. Patients with any active autoimmune disease; known or tested positive for Human Immunodeficiency Virus (HIV) or Acquired Immunodeficiency Syndrome (AIDS); or a history of treatment with steroids or immunosuppressive drugs;
4. Rectal or colon cancer located more than 12 cm from the anal verge;
5. Patients with interstitial lung disease, non-infectious pneumonia, or uncontrolled systemic diseases (e.g., diabetes, hypertension, pulmonary fibrosis, and acute pneumonia);
6. Patients who experienced any Grade 2 or higher toxicity due to previous treatments (according to Common Terminology Criteria for Adverse Events (CTCAE) version 5), which has not resolved (excluding anemia, alopecia, and skin pigmentation changes); known or suspected allergy to any of the related drugs used in the trial;
7. Pregnant or breastfeeding women.