Inclusion Criteria:
1. Age ≥ 18 years.
2. Patients voluntarily join the study and sign an informed consent form for the study.
3. ECOG PS score 0-3 (patients with PS score 2-3 would be enrolled if due to the tumor disease and anticipated to be improved at investigators' decision).
4. Histologically documented, stage III, IV non-Small Cell Lung Cancer (according to version 8th of the International Association for the Study of Lung Cancer Staging Manual in Thoracic Oncology) and previously untreated systematically(excluding local therapy for local lesions or symptomatic relief, palliative radiotherapy, intervention, intrathecal injection, nerve block, etc.).
5. Patients with stage III NSCLC who are not suitable for surgery at a multidisciplinary discussion or investigators' assessment.
6. Patients with at least one measurable target lesion by CT scan/MRI (RECISTv1.1).
7. Patients with active brain metastases and liver metastases could be enrolled (Concurrent radiotherapy, intervention, dehydration, and other local treatment are permitted).
8. Interstitial pneumonia, drug-induced pneumonia, radiation pneumonitis requiring steroid therapy, or active pneumonia with clinical symptoms of grade 2, can be included after symptomatic treatment until recovery to grade 0-1.
9. Fertile men and women of childbearing age must agree to take effective contraceptive measures from signing the main informed consent until 180 days after the last dose of the study drug. Women of childbearing potential include premenopausal women and women within 2 years of menopause. Females of childbearing potential must have a negative pregnancy test ≤ 7 days prior to the first dose of study drug.
Exclusion Criteria:
1. All patients carry activating mutations of EGFR, ALK, ROS1, and RET. (No more mutation test needed).
2. Small cell lung cancer (including patients with mixed small cell lung cancer and non-small cell lung cancer).
3. Histopathologically or cytopathologically confirmed non-NSCLC.
4. Any prior treatment of antibody/drug that targets T-cell coregulatory proteins (not limited to CTLA-4 inhibitors or other agents targeting T cells).
5. Any tumor history within the past 5 years prior to the start of treatment in this study (except cured cervical carcinoma in situ, cured basal cell carcinoma, and bladder epithelial tumors with surgical resection alone and at least 5 consecutive years of disease-free survival).
6. Patients with active, unstable systemic disease, active infection, uncontrolled hypertension, heart failure (NYHA class \>= II), unstable angina pectoris, acute coronary syndrome, severe arrhythmia, severe liver, kidney, or metabolic diseases, HIV infection.
7. Pregnant or lactating women.
8. Systemic anti-tumor therapy planned within 4 weeks before first-line treatment or during medication after enrollment, including cytotoxic therapy, signal transduction inhibitors, immunotherapy (with the exception of thymosin, lentinan, and other immunomodulator therapy).
9. Major surgical treatment, incisional biopsy, or significant traumatic injury within 28 days before 1st line therapy.
10. Participation in other anti-tumor drug clinical trials within 4 weeks before first-line therapy.
11. Active, known, or suspected autoimmune diseases. Vitiligo and Type I diabetes mellitus with no systemic treatment are allowed. Residual hypothyroidism caused by autoimmune thyroiditis requiring only hormone replacement therapy is allowed.
12. With known mental illness, alcoholism, drug abuse, or other factors which may cause termination of this study, affect the safety of subjects, or collection of data and samples.
