The purpose of this study is to confirm the safety and efficacy of Apatinib plus Pemetrexed as the Maintenance Therapy in Advanced Lung Adenocarcinoma.

Lung adenocarcinoma is the most common NSCLC,most patient were diagnosed to advanced stage. Maintenance treatment is the continuation of treatment after first-line treatment and before the disease progresses. We consider to add apatinib,a tyrosine kinase inhibitor of VEGF,to the therapy of these patients. We designed the study to explore the possibility of apatinib for maintenance.

Inclusion Criteria:

1. Histologically or cytologically confirmed of lung adenocarcinoma, EGFR wild-type or known drug-resistant mutation, stage IV or irradiative stage IIIB.
2. Age ≥ 18 years;
3. Eastern Cooperative Oncology Group (ECOG) performance status of 0 - 1;
4. Patients had previously received at least 4 cycles of first-line, double chemotherapy and had no disease progression at baseline screening compared with baseline imaging prior to first-line chemotherapy；
5. Adequate hepatic, renal, heart, and hematologic functions: ANC ≥ 1.5×109/L, PLT ≥ 100×109/L, HB ≥ 90 g/L, TBIL ≤ 1.5×ULN, ALT or AST ≤ 2.5×ULN (or ≤ 5×ULN in patients with liver metastases), Serum Cr ≤ 1×ULN, Cr clearance ≥ 45 mL/min;

Exclusion Criteria:

1. Active brain metastases, meningococcal meningitis, patients with spinal cord compression, or imaging at CT or MRI examination revealed brain or pia mater disease（Patients who have completed treatment and whose symptoms are stable in the first 21 days of randomization may be enrolled in the study but may be diagnosed as having no intracerebral hemorrhage by MRI, CT or venography）；
2. Imaging (CT or MRI) showed that the tumor lesions were ≤ 5 mm from the major vessels or there was a central tumor invading local macrovascular；
3. Imaging (CT or MRI) showed significant cavitary or necrotic lung tumors, uncontrollable hypertension (systolic BP ≥140 mmHg or diastolic BP ≥90 mmHg, despite optimal medical therapy), grade II The above myocardial ischemia or myocardial infarction, poor control of arrhythmia (including QTc interval male ≥ 450 ms, female ≥ 470 ms); NYHA standards, Ⅲ ~ Ⅳ grade cardiac insufficiency, or cardiac ultrasound examination prompted left ventricular ejection Score (LVEF) <50%；
4. Coagulation dysfunction (INR> 1.5, PT> ULN +4s or APTT> 1.5 ULN), with bleeding tendency or ongoing thrombolysis or anti-blood coagulation treatment；Patients treated with anticoagulants or vitamin K antagonists such as warfarin, heparin, or the like；
5. Patients who had obvious hemoptysis within 2 months before screening, or experienced daily hemoptysis with a volume more than half a tea spoon (2.5ml) or above；
6. Patients who experienced bleeding symptoms of clinical significance within 3 months before screening, or with confirmed bleeding tendency such as hemorrhage of digestive tract, hemorrhagic gastric ulcer, baseline occult blood in stool ++ and above, or vasculitis, etc.
7. Patients who manifested arterial/venous thrombus events, e.g. cerebrovascular accident (Including temporary ischemic attack, cerebral hemorrhage, cerebral infarction), deep venous thrombosis and pulmonary embolism, etc., within 12 months before screening（Such as hemophilia, coagulation disorders, thrombocytopenia, hypersplenism and so on）；
8. Patients whose routine urine tests indicate that urine protein ≥ ++ or verifies that the 24-h urine protein quantitation ≥ 1.0 g；
9. Confirmed ALK gene fusion；
10. Anti-angiogenic drugs were used during first-line chemotherapy。