A Clinical Study to Evaluate the Efficacy and Safety of HLX26 (Anti-LAG-3 Monoclonal Antibody Injection) Combined With Serplulimab and Chemotherapy in Previously Untreated Advanced NSCLC Patients

Key Inclusion Criteria: Stage IV (AJCC 8th Edition) non-small cell lung cancer confirmed by histology or cytology. No EGFR sensitive mutation or ALK, ROS1 rearrangement. Have not received systemic treatment for stage IV disease. For patients who have received adjuvant or neoadjuvant treatment, if the adjuvant/neoadjuvant treatment has been completed for at least 6 months, they are allowed to be enrolled. At least one measurable lesion evaluated by the investigator per RECIST v1.1. Subjects must provide qualified tumor tissue samples for the detection of PD-L1 and LAG-3 expression level. Have adequate organ function with expected survival period ≥ 12 weeks and ECOG score of 0 or 1. Key Exclusion Criteria: Subjects with other histopathological types including small cell lung cancer, neuroendocrine cancer or sarcoma. Have other malignant tumors within 3 years. Pleural effusion, pericardial effusion or ascites that require clinical intervention. Myocardial infarction and poorly controlled arrhythmia occurred within six months before the first administration of the study drug. III - IV cardiac insufficiency per NYHA standard or left ventricular ejection fraction<50%. Patients with active pulmonary tuberculosis. Patients with previous or current interstitial pneumonia, pneumoconiosis, radiation pneumonitis, drug-related pneumonitis, or severe pulmonary function impairment that may interfere with the detection and management of suspected drug-related pulmonary toxicity. Patients who have known active autoimmune diseases or suspected auto-immue disease. Patients in stable condition and do not require systemic immunosuppressant therapy are allowed to be enrolled. Require systemic treatment with corticosteroids (> 10 mg/day prednisone or equivalent) or other immunosuppressive agents within 14 days prior to the first dose of the study products or during the study. Patients who have received any T-cell costimulatory agents or immune checkpoint blockade therapy, including but not limited to cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) inhibitors, PD-1 inhibitors, PD-L1 inhibitors. Patients with a history of severe allergy to any monoclonal antibody products.