This is an open-label, Phase I study of QN-023a (allogeneic CAR-NK cells targeting CD33) in relapsed/refractory Acute Myeloid Leukemia (AML).

The clinical study is to evaluate the safety, tolerability and preliminary efficacy of QN-023a in patients with relapsed/refractory AML,where a "3+3" enrollment schema will be utilized at dose escalation stage. Up to 19 patients will be enrolled.

Key Inclusion Criteria:

• Provision of signed and dated informed consent form (ICF)
• ≥18 years old
• Diagnosis of r/r AML
• Subjects with CD33 positive leukemia cells
• Eastern Cooperative Oncology Group (ECOG) performance status ≤1
• Adequate organ function as defined in the protocol
• Donor specific antibody (DSA) to QN-023a: MFI <= 2000

Key Exclusion Criteria:

• Allergic to drug used in this study
• Accept other anti-tumor drugs/therapies within certain time of day 0 (first QN-023a dose infusion), time window and drug defined in the protocol.
• received systemic immunosuppressive therapy within 7 days of day 0, or likely to require systemic immunosuppressive therapy
• Acute Promyelocytic Leukemia (APL)
• Central nervous system Leukemia.
• Uncontrolled, active clinically significant infection
• Clinically significant cardiovascular disease as defined in the protocol
• Known HIV infection, active Hepatitis B (HBV) or Hepatitis C (HCV) infection
• History of central nervous system (CNS) disease such as stroke, epilepsy.
• Females are pregnant or lactating
• Investigator-assessed presence of any medical or social issues that are likely to interfere with study conduct or may cause increased risk to subject