• Sign written informed consent before implementing any experimental procedures;

• Male or female, aged 18 or above and 85 or below;

• Patients diagnosed with rectal adenocarcinoma through primary lesion biopsy and histopathological examination;

• Patients with cT stage ≥ T3 or cN stage N1+, M0 or EMVI (+) or MRF (+) or suspected lateral lymph node metastasis (\>5mm) who are determined to be operable and require neoadjuvant therapy through imaging and colonoscopy examination.

• According to imaging and colonoscopy examination, the main body of the patient's tumor is located ≤ 15cm away from the anal edge;

• According to the criteria for evaluating the efficacy of solid tumors (RECIST version 1.1), there should be at least one measurable lesion on imaging;

• The patient has not received any anti-tumor treatment in the past, including but not limited to surgery, radiotherapy, chemotherapy, immunotherapy, targeted therapy, etc;

• ECOG score 0-1 points;

• Adequate organ function, subjects must meet the following laboratory indicators:

‣ In the past 14 days without using granulocyte colony-stimulating factor, the absolute neutrophil count (ANC) was ≥ 1.5x109/L.

⁃ Platelets ≥ 100 × 109/L without blood transfusion in the past 14 days.

⁃ Hemoglobin\>9g/dL in the past 14 days without blood transfusion or use of erythropoietin;

⁃ Total bilirubin ≤ 1.5 x upper limit of normal (ULN);

⁃ Aspartate transaminase (AST) and alanine transaminase (ALT) levels are ≤ 2.5 × ULN

⁃ Blood creatinine ≤ 1.5 × ULN and creatinine clearance rate (calculated using Cockcroft Gault formula) ≥ 60 ml/min;

⁃ Good coagulation function, defined as International Normalized Ratio (INR) or Prothrombin Time (PT) ≤ 1.5 times ULN;

⁃ Normal thyroid function is defined as thyroid stimulating hormone (TSH) within the normal range. If the baseline TSH exceeds the normal range, subjects with total T3 (or FT3) and FT4 within the normal range can also be enrolled;

⁃ The myocardial enzyme spectrum is within the normal range (simple laboratory abnormalities that are deemed clinically insignificant by the researchers are also allowed to be included)

⁃ For female subjects of childbearing age, a urine or serum pregnancy test with negative results should be conducted within 3 days prior to the first administration of the study drug (Day 1 of the first cycle). If the urine pregnancy test result cannot be confirmed as negative, a blood pregnancy test is required. Non childbearing women are defined as those who have been postmenopausal for at least one year or have undergone surgical sterilization or hysterectomy; If there is a risk of conception, all subjects (male or female) must use contraceptive measures with an annual failure rate of less than 1% throughout the entire treatment period until 120 days after the last administration of the study drug (or 180 days after the last administration of chemotherapy drug).