SCRT Followed by CAPOX + Bev ± PD-1 Inhibitor for TNT in LARC

Inclusion Criteria: * Histopathologically confirmed rectal adenocarcinoma with no prior antitumor therapy. * Exclusion of patients with BRAF mutations or MSI-H status, as determined by pre-enrollment genetic testing including RAS, BRAF, and MSI analysis. RAS mutation status is permitted regardless. * Absence of severe intestinal obstruction symptoms and no evidence of distant metastasis confirmed by imaging examinations such as CT, MRI, or PET/CT. * Confirmation as locally advanced rectal cancer by rectal MRI, meeting one or more of the following criteria: T3c-d or T4, N2, EMVI(+), MRF(+), lateral lymph node metastasis; or patients with low-lying rectal cancer (≤5 cm from the anal verge) unsuitable for sphincter-preserving surgery prior to neoadjuvant therapy. * Age 18 to 75 years. * ECOG Performance Status of 0 to 1, without severe comorbid medical conditions. * Adequate organ function: Hematopoietic: Hemoglobin ≥90 g/L, Platelets ≥80 × 10\^9/L, Absolute Neutrophil Count ≥1.5 × 10\^9/L. Hepatic: ALT and AST \< 2.5 × ULN. Renal: Serum Creatinine \< 1.5 × ULN. * Provision of signed and dated written informed consent. Exclusion Criteria: * Patients found to have BRAF mutations or MSI-H status. * Patients who have previously received chemotherapy, radiotherapy, immunotherapy, targeted therapy, or surgical resection for colorectal cancer prior to enrollment. * History or presence of another malignancy (except for early-stage basal cell carcinoma or carcinoma in situ of the cervix) within the past 3 years, with the disease not under control. * Patients who are pregnant (confirmed by serum or urine β-HCG test) or breastfeeding. * Patients with severe cardiac, hepatic, renal, neurological, or psychiatric diseases. * Patients with active infections. * Poor overall health status, with an ECOG performance status ≥2. * Patients who have undergone organ transplantation requiring immunosuppressive therapy, or those requiring long-term corticosteroid treatment for autoimmune diseases. * Patients with comorbid conditions that, in the investigator's judgment, seriously endanger the patient's safety or affect the completion of the study. * Known hypersensitivity to any of the study drugs.