Study of Apatinib in RET Fusion Positive Advanced Non-small Cell Lung Cancer

Inclusion Criteria: * Aged ≥18 and ≤80 years. * ECOG performance status of 0 to 1. * Life expectancy of more than 12 weeks. * At least one measurable lesion exists.(RECIST 1.1) * Histologically or cytologic confirmed RET fusion positive advanced Non-small cell lung cancer who failed to prior therapies. * Required laboratory values including following parameters: ANC: ≥ 1.5 x 10\^9/L, Platelet count: ≥ 80 x 10\^9/L, Hemoglobin: ≥ 90 g/L, Total bilirubin: ≤ 1.5 x upper limit of normal, ULN, ALT and AST: ≤ 1.5 x ULN, BUN and creatine clearance rate: ≥ 50 mL/min LVEF: ≥ 50% QTcF: \< 470 ms * Signed informed consent * Females of child-bearing potential must have negative serum pregnancy test. Sexually active male and those having childbearing potential must practice contraception during the study. Exclusion Criteria: * Squamous carcinoma (including adeno-squamous carcinoma), small cell lung cancer * Subjects with third space fluid that can not be controled by drainage or other methods. * Obvious cavity or necrosis formed in the tumor * Uncontrolled hypertension * Hymoptysis, more than 2.5ml daily * Thrombosis in 12 months, including pulmonary thrombosis, stroke, or deep venous thrombosis * Received big surgery, had bone fracture or ulcer in 4 weeks * Urine protein \>++, or urine protein in 24 hours\> 1.0g * pregnant or lactating woman * Receiving any other antitumor therapy. * Known history of hypersensitivity to apatinib or any of it components.