VAC Regimen for AML Patients Who Failed to Response to VA Regimen

Inclusion Criteria: Patients with AML who are not suitable for intensive chemotherapy according to the WHO diagnosis: age ≥60 years or age \<60 years but fulfil the following criteria; 1. Age 18 to 59 years; 2. Eastern Cooperative Oncology Group (ECOG) physical status score of 2 or 3; 3. Expected survival time ≥3 months; 4. Or fulfilment of severe cardiac, pulmonary, hepatic, or renal disease; (A) Presence of a cardiac history of congestive heart failure, or ejection fraction ≤ 50%, or presence of chronic stable angina; (B) Lung carbon monoxide diffusing capacity (DLCO) ≤ 65%, or first forced expiratory volume (FEV1) ≤ 65%; (C) Moderate hepatic impairment with total bilirubin \> 1.5 to ≤ 3.0 x upper limit of normal (ULN); (D) Creatinine clearance ≥ 30 mL/min to \< 45 mL/min; 5. Not received radiotherapy, treatment regimens other than the VA regimen, or haematopoietic stem cell transplantation within 4 weeks prior to enrolment; 6. Other comorbidities that, in the judgement of the physician, make the administration of intensive chemotherapy unsuitable; 7. Ability to understand and willingness to sign the informed consent for this trial; 8. The patient refuses intensive chemotherapy and has the willingness to accept non-intensive chemotherapy. Exclusion Criteria: 1. Patients with a history of myeloproliferative neoplasms (MPN), including myelofibrosis, thrombocythemia, polycythaemia vera, chronic granulocytic leukemia (CML) with or without BCR-ABL1 translocation, and AML or acute promyelocytic leukemia (APL) with BCR-ABL1 translocation; 2. Patients with FLT3 mutations and who were treated with targeted agents (inclusion is possible if the use of specific targeted agents is discontinued); 3. Patients with less than 50% reduction of blasts after VA regimen; 4. Patients with active CNS involvement; 5. With prior treatment with chidamide; 6. Clinically uncontrolled active infections (including bacterial, fungal or viral infections) and organ hemorrhage; 7. Pregnant or lactating women; 8. Participation in any other clinical trial within 3 months prior to VAC regimen; 9. With other malignant tumours; 10. With uncontrolled mental disorders; 11. Any other condition that, in the opinion of the investigator, makes it inappropriate to participate in this trial.