Study of Selinexor Combined With Chidamide in Relapsed/Refractory Acute Leukemia (AML) Patients

Inclusion Criteria: 1. Men and women aged 18 to 75 years old. 2. Diagnosis of relapsed or refractory AML (defined according to the the World Health Organization \[WHO\] 2016 criteria) of any type except for acute promyelocytic leukemia (APL; AML M3). 3. Eastern Cooperative Oncology Group (ECOG) performance status of 2-3. 4. Patients whose expecting survival time will be more than 3 months. 5. One of the serious heart, lung, liver, kidney disease: 1. Cardiac history of Congestive Heart Failure (CHF) requiring treatment or Ejection Fraction \<= 50% or chronic stable angina; 2. Diffusing capacity of the Lung for Carbon Monoxide (DLCO) \<= 65% or Forced Expiratory Volume in 1 second (FEV1) \<= 65%; 3. Moderate hepatic impairment with total bilirubin \> 1.5 to \<= 3.0 × Upper Limit of Normal (ULN); 4. Creatinine clearance \>= 30 mL/min to \< 45 ml/min; 6. Other comorbidities that the physician judges to be incompatible with intensive chemotherapy. 7. Patients who had not received radiotherapy, chemotherapy, targeted therapy within one week before enrollment. 8. Fertile women and men whose partner is of childbearing potential or pregnant should agree to practice complete abstinence or to use a condom during therapy and dose interruptions and for 90 days after the last treatment. 9. Patients who are suitable for intensive chemotherapy but refuse it. 10. Patients who have known and voluntarily signed the informed consent (ICF). Exclusion Criteria: 1. History of any malignancies prior to study entry with exception noted in the protocol. 2. Patients who had previously been treated with selinexor and/or chidamide. 3. Patients with APL/AML M3, or t(9;22)(q34.1;q11.2); BCR-ABL1 positive AML. 4. Absolute white blood cell count \>=100\*10\^9/L. 5. Persistent toxicity due to previous chemotherapy or radiotherapy did not recover to 2 grade. 6. Presence of CNS leukemia. 7. Patients who had undergone cardiac angioplasty or stent implantation within 12 months before signing the informed consent form, or had myocardial infarction or instability history of defined angina or other clinically significant cardiac events. 8. Ucontrolled active infection (including bacterial, fungal or viral infections) and bleeding from internal organs. 9. Pregnant and lactating women. 10. Participated in any other clinical trials within 3 months before signing the informed consent form. 11. Patients who are unsuitable for this study judged by clinicians.