New combo therapy aims to shrink rectal tumors and save organs

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Age between 18 and 80 years; ECOG performance status 0-1; 2. Histopathologically confirmed rectal adenocarcinoma via colonoscopy; pMMR or MSS phenotype; 3. Rectal MRI stage II/III (excluding T4b); distal tumor margin ≤ 12 cm from the anal verge; 4. Willingness to comply with study procedures; consent to use tissue and blood samples for medical research purposes; 5. No prior history of radiotherapy, chemotherapy, or immunotherapy; 6. No immune system diseases (e.g., systemic lupus erythematosus, rheumatoid arthritis, systemic vasculitis, scleroderma, pemphigus, dermatomyositis, mixed connective tissue disease, hyperthyroidism/hypothyroidism, ulcerative colitis, autoimmune hemolytic anemia, HIV infection, etc.); 7. No severe cardiac, pulmonary, hepatic, or renal dysfunction; no jaundice or gastrointestinal obstruction; 8. No concurrent acute infection; 9. Baseline laboratory evaluations completed as required, with results obtained within 14 days before randomization, and laboratory values meeting the following criteria (per CTCAE 5.0): * White blood cell count ≥ 2000/μL; * Neutrophil count ≥ 1500/μL; * Platelet count ≥ 100×10³/μL; * Hemoglobin ≥ 9.0 g/dL; * Serum creatinine ≤ 1.5×upper limit of normal (ULN) or creatinine clearance \> 50 mL/min (female: creatinine clearance = \[140 - age (years)\] × body weight (kg) × 0.85 / (72 × serum creatinine (mg/dL)); male: creatinine clearance = \[140 - age (years)\] × body weight (kg) × 1.00 / (72 × serum creatinine (mg/dL))); * AST ≤ 3×ULN, ALT ≤ 3×ULN, total bilirubin ≤ 1.5×ULN; 10. No psychiatric/psychological disorders affecting social function; 11. Negative serum pregnancy test (blood HCG) within 1 week before randomization for women of childbearing potential; 12. Women of childbearing potential must agree to use effective contraception during the study period and for 5 months after the last dose of study drug; 13. Male subjects who are sexually active with women of childbearing potential must agree to use effective contraception during the study period and for 7 months after the last dose of study drug, and must refrain from sperm donation during this period. Exclusion Criteria: 1. Multiple primary cancers or concurrent other malignant tumors; 2. Patients requiring emergency surgery due to intestinal obstruction, intestinal perforation, gastrointestinal bleeding, etc.; 3. Factors affecting oral drug absorption (e.g., inability to swallow, nausea/vomiting, diarrhea, intestinal obstruction, etc.); 4. Any uncontrolled, severe concomitant diseases; 5. Hypersensitivity to any component of the study drugs; 6. Expected survival \< 5 years for any reason; 7. Planned or previous organ/bone marrow transplantation; 8. Treatment with immunosuppressants or corticosteroids within 1 month before enrollment; 9. Central nervous system disorders that may impair ability to provide informed consent or comply with study procedures, as determined by the investigator; 10. Other conditions that may prevent completion of study treatment (e.g., alcoholism, drug addiction, etc.); 11. Pregnant or breastfeeding women.