This is a open-label, single-arm study to investigate the safety and efficacy of consolidative chemotherapy with camrelizumab, an anti-PD-1 antibody drug following short course radiotherapy and subsequent surgical therapy in patients with locally advanced resectable rectal cancer.

Patients with locally advanced rectal cancer (cT3-4 or N+) are assigned to receive preoperative 5 × 5 Gy irradiation over 5 days with consolidation chemotherapy consisting two cycles of CAPOX chemotherapy and camrelizumab, an anti-PD-1 antibody drug for two cycles. Subsequent surgical therapy is performed to evaluate the safety and efficacy.

Inclusion Criteria:

1. Patients who personally provided written consent for participation in the study
2. Treatment-naive patients with rectal cancer, in whom the inferior margin of the tumor is at a distance of 10 cm or less from the AV before CRT
3. Primary rectal cancer histopathologically confirmed to be adenocarcinoma
4. Clinical stage of T3/T4 or N positive and M0,before CRT
5. Patients with the ECOG performance status of 0 or 1 at the time of enrollment
6. Women of childbearing potential who consent to practicing contraception during the period from giving informed consent to at least 23 weeks after the last dose of therapy
7. Male patients who consent to practicing contraception during the period from giving informed consent to at least 31 weeks after the last dose of the study drug

Exclusion Criteria:

1. Patients with recurrent rectal cancer or a history of pelvic radiation
2. Patients with a history of inflammatory bowel disease
3. Patients with a history of pneumonitis or interstitial lung disease
4. Patients with concurrent autoimmune disease or a history of chronic or recurrent autoimmune disease
5. Patients requiring treatment with systemic corticosteroids or immunosuppressants or who have received these treatments within 14 days before enrollment in the study
6. Patients with a history of thyroid dysfunction
7. Patients with a history or finding of cardiovascular risk
8. Patients who are positive for any of the following: HIV1 antibody, HIV2 antibody, HTLV1 antibody
9. Patients who are pregnant or lactating or who may be pregnant
10. Patients with significant unstable mental diseases or other medical diseases that may interfere with the safety of the subjects, obtaining informed consent, or compliance with the procedures for the clinical study