A Series of Neoadjuvant Chemoradiotherapy Combined With Immunotherapy for Locally Advanced Rectal Cancer

Inclusion Criteria:

1. Signed a written informed consent form and volunteered to join the study;

2. .Age: 18-75 years old, male or female;

3. Pathohistologically confirmed rectal adenocarcinoma, along with immunohistochemicalresults of pMMR or genetic test results of MSS;

4. The baseline clinical stage assessed by MRI was T1-2N1-2M0 or T3N0-2M0, MRF (-),lateral lymph nodes (-);

5. The lower tumor margin is 10cm away from the anal margin;

6. Surgical resection;

7. Ability to swallow tablets normally;

8. ECOG PS 0-1；

9. Have not received any anti-tumor treatment for rectal cancer, includingradiotherapy, chemotherapy, surgery, etc.;

10. Plan to undergo surgery after the completion of the neoadjuvant therapy;

11. No contraindications to surgery;

12. Main organ function is normal.

Exclusion Criteria:

1. Previous history of allergy to monoclonal antibodies, any component oftislelizumab,and capecitabine;

2. Previously has received or is receiving any of the following treatments: A)Any tumor-specific surgery, radiotherapy, chemotherapy, targeted therapy,immunotherapy, etc; B)Treatment with immunosuppressive drugs or systemic hormoneswithin 2 weeks of first use (dose> 10mg / day prednisone or equivalent dose);inhaled or topical steroids and dose> 10mg / day prednisone or equivalent dose ofadrenocorticoid replacement in the absence of active autoimmune disease; C)Havingreceived a live attenuated vaccine within 4 weeks before the first use of the studydrug; D)Major surgery or severe trauma within 4 weeks before the first use of studydrug;

3. History of any active autoimmune or autoimmune disease, including but not limitedto: interstitial pneumonia, enteritis, hepatitis, hypophysitis, vasculitis,nephritis, hyperthyroidism, hypothyroidism (considered after hormone replacementtherapy); patients with psoriasis or asthma / allergy in childhood and adultswithout any intervention, but patients requiring medical intervention withbronchodilators should not be included;

4. A history of immunodeficiency, including a positive HIV test, or other acquired orcongenital immunodeficiency disease, or a history of organ transplantation orallogeneic bone marrow transplantation;

5. Not well controlled cardiac clinical symptoms or disease, including but not limitedto: such as (1) grade NYHA II above heart failure, (2) unstable angina, (3)myocardial infarction within 1 year, (4) clinical meaningful supraventricular orventricular arrhythmia without clinical intervention or clinical intervention stillpoor control;

6. Severe infection (Grade CTCAE> 2) within 4 weeks prior to the first use of studydrug, Such as severe pneumonia, bacteremia, infection complications requiringhospitalization; Baseline chest imaging indicated the presence of active lunginflammation, presence of symptoms and signs and signs of infection within 14 daysprior to the first administration of study drug or need for oral or intravenousantibiotics, Except for the preventive use of antibiotics; Found active tuberculosisinfection by history or CT, Or those with a history of active tuberculosis infectionwithin 1 year prior to enrollment, Or those with a history of active tuberculosisinfection more than 1 year ago but without formal treatment;

7. Presence of active hepatitis B (HBV DNA 2000 IU / mL or 104copies / mL), hepatitis C (positive for hepatitis C antibody, and HCV RNA above the lower limit of detectionof the analytical method);

8. A diagnosis of other malignancies within 5 years prior to the first use of studydrug, unless a malignancy with low risk of metastasis or death (5-year survival> 90%), such as adequately treated skin basal cell carcinoma or squamous cellcarcinoma in situ, are considered;

9. Women in pregnancy or lactation;

10. Other factors, as judged by the investigator, may lead to forced termination of thestudy, such as other serious illness (including mental illness), alcohol, substanceabuse, family or social factors, which may affect the safety or compliance of thesubject.