This is a prospective, multi-center, single-arm, phase 2 study aiming to assess the efficacy and safety of adjuvant use of Ensartinib in stage IB-IIIA non-small cell lung cancer (NSCLC) with positive ALK-fusion. Enrolled patients will take Ensatinib for 3 years or until recurrence of the disease or intolerable toxicity, following complete tumour resection with or without adjuvant standard chemotherapy.

Inclusion Criteria:

• Completely resected pathological stage IB-IIIA NSCLC with ALK-fusion positive (confirmed by FISH, IHC or NGS).
• Males or females aged ≥18 years, ≤75 years.
• ECOG performance status 0-2.
• Completely recovered from surgery or standard postoperative chemotherapy before receiving adjuvant ensatinib treatment. (When starting the study treatment, the patient must have recovered from all toxicities greater than CTCAE Grade 1 caused by the previous treatment, except for hair loss and Grade 2 neuropathy related to previous platinum-based treatments).
• Clinical examinations before treatment report no signs of disease recurrance.
• With enough tumor histology specimens (non-cytology) for molecular marker analysis.
• hemoglobin concentration ≥ 100 g/L (permit to maintain hematologic criteria by blood transfusion); absolute neutrophil count (ANC) ≥1.5×10^9/L; platelet count ≥100×10^9/L.
• Liver Function: TBil ≤2xULN; ALT and AST ≤2.5xULN;
• Renal Function: Cr ≤1.5xULN, and Ccr ≥60ml/min;
• Signed inform consent form by patient or his/her legal representative.
• Comply with study protocol and procedure, and be able to take oral medication.
• Female patients of childbearing potential must have a negative urine pregnancy test within 7 days before study treatment.
• Eligible patients of reproductive potential (both sexes) must agree to use a reliable method of birth control before enrollment, during the study period and for at least 8 weeks after their last dose of study therapy.

Exclusion Criteria:

• Having targeted medication therapy (including tyrosine kinase inhibitor or monoclonal antibody) and experimental therapy for NSCLC in the past.
• Having local radiotherapy of NSCLC.
• Known allergy to Ensatinib or any of the ingredients in this product.
• Previously suffering from interstitial lung disease, drug-induced interstitial disease, radiation pneumonia that requires hormone therapy, or any clinically evidenced active interstitial lung disease; CT scan at baseline revealed the presence of idiopathic pulmonary fibrosis.
• Any unstable systemic disease, including: active infection, uncontrolled high blood pressure, unstable angina pectoris, angina pectoris that started within the last 3 months, congestive heart failure (≥ New York Heart Association [NYHA] II Grade), myocardial infarction (6 months before enrollment), severe arrhythmia requiring medical treatment; liver, kidney or metabolic diseases.
• Women who are pregnant or breastfeeding.
• Having history of neurological or psychiatric disorders, including epilepsy or dementia.
• Other conditions investigators evaluate that patient is not eligible to this study.