Combined PD1 Inhibitor and Decitabine in Elderly Patients With Relapse and Refractory Acute Myeloid Leukemia

Inclusion Criteria: * Age: 60-75 * Relapsed and refractory patients with acute myeloid leukemia via morphology and immunology * ECOG：0-2 * Life expectancy ≥ 3 months * Adequate laboratory parameters during the screening period as evidenced by the following: 1. Creatinine clearance≥30 mL/min and serum Creatinine ≤ 160µmol/L 2. ALT and AST ≤ 3 × upper limit of normal (ULN) 3. FEV1,FVC,DLCO ≥ 50% predicted value 4. Left ventricular ejection fraction (LVEF) ≥ 40%, no symptomatic arrhythmia 5. Able to understand and sign an informed consent form (ICF). Exclusion Criteria: * Treatment-related AML * Allergic to Camrelizumab, Decitabine, other monoclonal antibody or pharmaceutical excipients * Use of immunosuppressive drug within 2 weeks before entering the group * Abnormal liver and kidney function(does not meet the inclusion criteria) * Suffering from heart failure * Active tuberculosis or HIV positive * Active hepatitis: Hepatitis B(HBsAg positive and HBV DNA≥500IU/mL), and hepatitis C(HCV RNA positive, abnormal liver function) ,Hepatitis B and hepatitis C infection in common. * Active, known or suspected autoimmune disease. Subjects who were in a stable state without systemic immunosuppressive therapy were admitted * Concurrent medical condition requiring the long-term use of immunosuppressive medications, or immunosuppressive doses of systemic corticosteroids \> 10 mg/day topical prednisone or equivalent * Suffer from other hematological neoplasm * Known history of use other immune checkpoint inhibitor * Other factors that may lead to the study termination, such as severe disease or abnormal laboratory tests or family or social factors affecting subjects safety or test data and sample collection.