Short-Course Radiotherapy Followed by Neoadjuvant Chemotherapy and Camrelizumab in Locally Advanced Rectal Cancer (UNION)

Inclusion Criteria:

1. Patients or their family members agree to participate in the study and sign theinformed consent form;
2. Age 18-75 years, male or female;
3. Histologically confirmed T3-44 and/or N+ rectal adenocarcinoma (AJCC/UICC TNM staging (8th Edition, 2017);
4. inferior margin ≤ 10 cm from the anal verge;
5. It is expected to reach R0;
6. ECOG performance status score is 0-1;
7. Swallowing pills normally;
8. Untreated with anti-tumor therapy for rectal cancer, including radiotherapy,chemotherapy, surgery, etc;
9. Surgical treatment is planned after neoadjuvant treatment;
10. There was no operative contraindication;
11. Laboratory tests were required to meet the following requirements: white blood cell (WBC) ≥ 4×109/L; Absolute neutrophil count (ANC) ≥ 1.5×109/L;Platelet count ≥ 100×109/L; Hemoglobin ≥90 g/L; Serum total bilirubin ≤ 1.5 × upperlimit of normal (ULN); Serum alanine aminotransferase (ALT) and aspartateaminotransferase (AST) ≤ 2.5 × ULN; Serum creatinine ≤1.5 times the upper limit ofnormal value or creatinine clearance rate ≥50 mL/min; International normalized ratio (INR) ≤ 1.5 × ULN; Activated partial thromboplastin time (APTT) ≤ 1.5 × ULN
12. Males or females with reproductive ability who are willing to use contraception in thetrial;

Exclusion Criteria:

1. Documented history of allergy to study drugs, including any component of Camrelizumab,capecitabine, irinotecan, oxaliplatin and other platinum drugs;
2. Have received or are receiving any of the following treatments: Any radiotherapy, chemotherapy or other anti-tumor drugs for tumor; Patients who needto be treated with corticosteroid (dose equivalent to prednisone of >10 mg/day) orother immunosuppressive agents within 2 weeks prior to study drug administration;Received live attenuated vaccine within 4 weeks before the first use of the studydrug; Major surgery or severe trauma within 4 weeks before the first use of the studydrug;
3. Any active autoimmune disease or history of autoimmune disease;
4. Have a history of immunodeficiency, including HIV positive, or other acquired orcongenital immunodeficiency diseases, or have a history of organ transplantation orallogeneic bone marrow transplantation;
5. There are clinical symptoms or diseases of heart that are not well controlled;
6. Severe infection (CTCAE > 2) occurred within 4 weeks before the first use of the studydrug; Baseline chest imaging revealed active pulmonary inflammation, signs andsymptoms of infection within 14 days prior to the first use of the study drug, or oralor intravenous antibiotic therapy, except for prophylactic use of antibiotics;
7. Patients with active pulmonary tuberculosis infection found by medical history or CTexamination, or with a history of active pulmonary tuberculosis infection within oneyear before enrollment, or with a history of active pulmonary tuberculosis infectionmore than one year ago but without regular treatment;
8. The presence of active hepatitis B (HBV DNA > 2000 IU/mL or 104 copies/mL) waspositive for hepatitis C (hepatitis C antibody) and HCV RNA was higher than the lowerlimit of analytical method;
9. Female subject who is pregnant or breastfeeding;
10. Patients who are not suitable for participation in clinical trials in the opinion ofthe investigator