Toripalimab as Maintenance Therapy in Patients With Driver-gene Negative Advanced NSCLC After First-line Chemotherapy

Criteria: Inclusion Criteria: * Fully understand the research and voluntarily sign the informed consent form (ICF) * Age 18 to 75 years * Histological or cytological documentation of non-small cell lung cance. * Diagnosed as stage IV by imaging (staging according to AJCC eighth edition). * Gene test is negative for EGFR, ALK, ROS1 confirmed by molecular pathology (tissue, ARMS method or NGS). * Previously received first-line standard chemotherapy for non-small cell lung cancer (platinum combined with third-generation chemotherapy drugs in a two-drug combination regimen: pemetrexed or paclitaxel or docetaxel or gemcitabine or vinorelbine combined with cisplatin or carboplatin), and which were assessed the effectiveness by imaging(SD, PR or CR). * At least one measurable lesion according to Response Evaluation Criteria in Solid Tumors (RECIST) criteria measured within 4 weeks prior to registration. * ECOG performance status 0-1 * Expected overall survival time≥3 months * Adequate bone marrow, Coagulation function，hepatic and renal function should be assessed by the following laboratory requirements conducted within 7 days before starting study treatment: * Leukocytes ≥ 3.0 x109/ L, absolute neutrophil count (ANC) ≥ 1.5 x109/ L, platelet count ≥ 100 x109/ L, hemoglobin (Hb) ≥9g/ dL. * Total bilirubin ≤ 1.5 x the upper limit of normal (ULN). * Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 2.5 x ULN. * Serum creatinine ≤ 1.5 x the ULN. * Calculated creatinine clearance or 24 hour creatinine clearance ≥ 40 mL/ min. * INR≤1.5, Activated partial thromboplastin time(APTT)≤1.5×ULN. * Patients with hepatitis B virus (HBV) infection and inactive/asymptomatic HBV carriers, or patients with chronic or active HBV, if the HBV DNA is \<500IU/ml, or 2500copies/ml at the time of screening,can enter the group. * Male subjects and women of childbearing age must have contraception within 24 weeks from the start of the study to the last time of using the drug. Exclusion Criteria: * Tumor histology or cytology pathology confirmed with small cell lung cancer components or sarcomatoid lesions. * Previously received any T-cell co-stimulation or immune checkpoint therapy, including but not limited to CTLA-4 inhibitors, PD-1 inhibitors, PD-L1 / 2 inhibitors or other drugs that target T cells. * Major autoimmune diseases. * Subjects who were vaccinated or planned to be vaccinated within 4 weeks before the first time using the study drug. * LD, drug-induced pneumonia, radiation pneumonitis requiring steroid therapy, or clinically active pneumonia or severe pulmonary dysfunction. * TB or subjects with a history of active tuberculosis infection ≤ 48 weeks before screening, whether or not treated. * Symptomatic cardiac disease, such as: heart failure above NYHA level 2, unstable angina pectoris, myocardial infarction occurred within 24 weeks, clinically significant supraventricular or ventricular arrhythmias require treatment or intervention. * Acquired immunosuppression (AIDS or major immunosuppressive agents) * Suffering from active viral hepatitis. Defined as: Hepatitis B virus (HBV) infection and HBV DNA ≥ 2500 copies / ml; or Hepatitis C virus (HCV) infection (quantitative test results of anti-HCV positive and HCV RNA are greater than the lower limit of detection) . * Mental illness, alcohol, drug or substance abuse * Pregnant or lactating women.