• Voluntarily sign the informed consent and be expected to complete the follow-up examination and treatment of the study procedures.

• Age of 18-70 years old (inclusive of the cut-off value), regardless of gender.

• Conforming to the diagnosis of AML according to the 2016 WHO classification, and conforming to the diagnostic criteria of relapsed and refractory acute myeloid leukemia in Chinese Guidelines for the Diagnosis and Treatment of relapsed and refractory acute myeloid Leukemia (2017 edition) :

∙ Relapsed AML diagnostic criteria: the reappearance of peripheral blood or bone marrow blasts after complete remission (CR); 5% (excluding other causes such as bone marrow regrowth after consolidation chemotherapy) or extramedullary leukemic cell infiltration.

‣ Refractory AML diagnostic criteria: newly diagnosed patients who failed to response to 2 courses of standard regimens; Patients who relapsed within 12 months after consolidation and intensive therapy; Patients relapsed after 12 months but failed to respond to conventional chemotherapy; Patients with two or more recurrences; Patients with persistent extramedullary leukemia.

• Flow cytometry confirmed the AML Blast CLL-1 expression positive (CLL-1 expression ≥50%).

• The patient has recovered from the toxicity of previous treatment, defined as CTCAE toxicity grade \<2 (unless the abnormality is tumor-related or is judged by the investigator to be stable and has little effect on safety or efficacy).

• ECOG performance status of 0-1 and predicted survival of more than 3 months.

• Have appropriate organ functions:

‣ Aspartate aminotransferase (AST) ≤3 times the upper limit of normal (ULN)

⁃ Alanine aminotransferase (ALT) ≤3 times ULN

⁃ Total bilirubin ≤1.5 times ULN

⁃ Serum creatinine ≤1.5 times ULN or creatinine clearance ≥60 mL/ minute

⁃ Hemoglobin ≥60g/L or maintained at that level after transfusion

⁃ Refers to terminal oxygen saturation ≥92%

⁃ Left ventricular ejection fraction (LVEF) ≥45%

• Female subjects were also considered for inclusion if they met the following criteria:

∙ Infertility, defined as:

⁃ Prior hysterectomy or bilateral oophorectomy, or

• Prior bilateral tubal ligation, or

• Menopausal (≥ 1 year of complete amenorrhea)

‣ be fertile, but have a negative serum pregnancy test at screening, and agree to use a medically approved contraceptive method (e.g., an intrauterine device, contraceptive pill, or condom) before and during study enrollment and up to 1 year after the last study use.

• Men of childbearing potential had to agree to barrier contraception or complete abstinence until 1 year after the last study dose.