This is a prospective, open-label, single-center, phase II umbrella trial designed to evaluate the efficacy and safety of neoadjuvant therapy for locally advanced colorectal cancer. Patients will be stratified into four cohorts based on microsatellite instability (MSI) status, KRAS mutation status, and the consensus molecular subtypes (CMS). Six arms are included across four cohorts and each arm will be assigned to a specific treatment regimen. The primary endpoint is the complete response rate. Secondary endpoints include safety, organ preservation rate (for rectal cancer only), R0 resection rate, surgical complications, treatment compliance, 3-year survival, and quality of life (QoL) score.

Inclusion Criteria:

1. Age 18-75 years old, female and male;
2. Pathological confirmed adenocarcinoma;
3. Stage II/III colon cancer, or stage II/III rectal cancer located less than 10 cm from the anal verge;
4. Treatment-naïve and no distance metastases;
5. KPS ≥ 70;
6. No radiotherapy, chemotherapy, immunotherapy, or any other anti-tumor therapy had been administered prior to enrollment;
7. Baseline blood and biochemical indicators meet the following criteria: neutrophils ≥ 1.5 × 10^9/L, Hb ≥ 90 g/L, PLT ≥ 100 × 10^9/L, ALT/ AST ≤ 2.5 ULN, Cr ≤ 1 ULN;
8. With good compliance and signed the consent form.

Exclusion Criteria:

1. Pregnancy or breast-feeding women;
2. Known history of other malignancies within 5 years;
3. Known history of severe neurological or mental illness (such as schizophrenia, dementia or epilepsy);
4. Current severe cardiac disease (cardiac dysfunction and arrhythmia), renal dysfunction and liver dysfunction;
5. Acute cardiac infarction or cerebral ischemic stroke occurred within 6 months before recruitment;
6. Uncontrolled infection which needs systemic therapy;
7. Active autoimmune disease or immunodeficiencies, known history of organ transplantation or systematic use of immunosuppressive agents;
8. Known history of human immunodeficiency virus (HIV) infection (i.e., HIV 1 to 2 antibody positive), active syphilis infection, active pulmonary tuberculosis infection;
9. Allergic to any component of the therapy.