Serplulimab Combined With CAPEOX + Celecoxib as Neoadjuvant Treatment for Locally Advanced Rectal Cancer

Inclusion Criteria: Willing and able to provide written informed consent. Male or female subjects ≧ 18 years ≦ 75 of age. Histological or cytological documentation of adenocarcinoma of the rectum. No previous any systemic anticancer therapy for rectal cancer disease. The lower margin of the tumor is less than 10cm from the anus verge. cT3N1M0, T4N0-1M0 MSS. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. At least one measurable lesion was evaluated according to RECIST 1.1. Eligible tumor tissues were identified for MSI/MMR assays. Expected survival of at least 3 months. Hepatitis B Surface Antigen (HBsAg) (-) and Hepatitis B Core Antibody (HBcAb) (-). If HBsAg (+) or HBcAb (+), HBV-DNA must be less than 2500 copies/mL or 500 IU/mL to be enrolled. Patients with HCV antibody (-) or HCV-RNA negative can be enrolled. Aspartate aminotransferase (AST) must be ≤ 3 x ULN for the lab. If HCV-RNA is positive, patients with both alanine aminotransferase (ALT) and aspartate aminotransferase (AST) performed ≤3×ULN could be enrolled. Patients infected with both hepatitis B virus and hepatitis C virus should be excluded (positive for HBsAg or HBcAb and positive for HCV antibodies). Exclusion Criteria: Patients with recurrent rectal cancer or a history of pelvic radiotherapy. Patients with a history of inflammatory bowel disease. Patients with acquired immunodeficiency syndrome (AIDS-related illnesses) or known human immunodeficiency virus (HIV) disease (HIV1 antibody, HIV2 antibody, HTLV1 antibody positive) should be excluded. Patients who are preparing for or have previously received an organ or bone marrow transplant. History of myocardial infarction, poorly controlled arrhythmias (including QTc interval ≥470 ms in women) in the 6 months prior to randomization (QTc interval calculated by Fridericia formula). According to New York College of Cardiology (NYHA) standards for Grade III-IV cardiac insufficiency or cardiac color ultrasound: left ventricular ejection fraction (LVEF) <50%.Poor hypertension control (systolic blood pressure ≥150 mmHg and/or diastolic blood pressure ≥100 mmHg), a past hypertensive crisis or hypertensive encephalopathy. Patients with active tuberculosis. The patients had previously been treated with other antibodies/drugs that target immune checkpoints, such as PD-1, PD-L1, and cytotoxic T lymphocyte-associated Antigen 4 (CTLA-4). Patients are participating in other clinical studies, or plan to start this study treatment less than 14 days from the end of the previous clinical study. Uncontrolled tumor-related pain. 11.A known history of severe allergy to any monoclonal antibody. 12.Known to be allergic to any oxaliplatin and capecitabine ingredients. 13.Pregnant or lactating women. 14.The investigators determined that the patient had other factors that might have led to the early termination of the study.