Neoajuvant Tislelizumab Combined with Chemotherapy for Initially Unresectable Stage IIIA/N2 Non-small Cell Lung Cancer

Inclusion Criteria: 1. Patients with initially untreated, unresectable stage III NSCLC (according to the International Association for the Study of Lung Cancer IASLC 8th Thoracic Tumor Stage) with non-small cell lung cancer 2. All patients received baseline PET/CT (or neck, upper thoracic and abdominal CT+ cranial MR) for clinical staging 3. Cytology/histology (mediastinoscopy or EBUS, etc.) confirmed N2 non-small cell lung cancer 4. For non-squamous cell carcinoma patients, if EGFR/ALK mutation status is unknown, tissue samples should be provided for EGFR/ALK gene testing before enrollment; For patients with squamous cell carcinoma, if EGFR/ALK mutation status is unknown, testing is not required during screening 5. ECOG (Performance status, PS) score 0-1 6. Hematology testings meet the following requirements * neutrophil ≥1.5\*109/L * Platelets ≥100\*109/L * Hemoglobin \> 9.0 g/dL * Serum creatinine ≤1.5ULN or creatinine clearance (Ccr) ≥40mL/min * AST/ALT≤ 3ULN * Total bilirubin ≤1.5ULN * FEV1≥1.2L or \> 40% of the estimated value * INR/APTT within normal range 7. The patient is over 18 years old 8. Measurable lesions (according to the RECIST 1.1 version) 9. Subject must understand and voluntarily sign informed consent prior to any study-related evaluation Exclusion Criteria 1. The patient presents with a confirmed or suspected autoimmune disorder. * Note: Patients with vitiligo, type I diabetes mellitus, or Hashimoto\'s thyroiditis who are hypothyroid but require only hormone replacement therapy may be included in the study if there are no obvious signs of relapse 2. Patients must have undergone systemic corticosteroid treatment (≥10mg prednisolone \[or equivalent\]/day) or received other immunosuppressive medications within 14 days prior to enrollment. * Note: Inhaled or topical corticosteroids and adrenal hormone replacement therapy (≥10mg prednisolone \[or equivalent\]/day) can also be accepted for individuals lacking clear evidence of autoimmune disorders 3. Patients with grade 3 or 4 interstitial lung disease 4. Have other malignant tumors and need anti-tumor therapy 5. Patients with previous malignancies (except skin malignancies other than melanoma, and in situ cancers of the following sites (bladder, stomach, colorectal, endometrial, cervix, melanoma, or breast) were not included in the study. Unless the malignancy has been in complete remission for two years or more and no additional antitumor therapy is required during the study period 6. The investigator believes that the patient is medically, psychologically, or physically incapable of completing this study or of understanding the patient handbook information 7. Previously received anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CTLA, and other drugs targeting T-cell co-stimulation or immune regulatory pathways 8. Presence of active Hepatitis B or C 9. HIV-positive or diagnosed with Acquired Immune Deficiency Disease (AIDS) 10. Allergy to the study drug 11. Women who are pregnant or breastfeeding