• Patients diagnosed with acute leukemia.

• Acute leukemia complex/refractory cases with poor response to conventional chemotherapy: 1) patients who did not achieve complete remission after 2 courses of treatment with standard induced remission regimen; 2) Recurrence within 6 months after the first remission; 3) Relapse 6 months after the first remission, but failure to be treated again with the original induced remission regimen; 4) Recurrent patients.

• At least 2 weeks or 5 half-lives (whichever is shorter) from the start of preconditioning chemotherapy after prior systemic treatment, except for immune checkpoint inhibitors/agonists; Systemic immune checkpoint inhibitor/agonist treatment is at least 3 half-lives away from pre-treatment chemotherapy (e.g., ipilimumab, etc.).

• Toxic reactions caused by previous antitumor therapy must be stabilized and returned to ≤ grade 1 (except for clinically insignificant toxicity, such as baldness).

• Over 14 years old, under 65 years old.

• Physical Strength score 0-3 (ECOG standard)

• No obvious active infection or graft-versus-host disease

• Expected survival ≥3 months

• Adequate kidney, liver, lung and heart function, defined as:

• Creatinine clearance (estimated by Cockcroft Gault formula) \> 60 mL/min; Serum ALT/AST ≤ 2.5 ULN; Total bilirubin ≤1.5 ULN, excluding subjects with Gilbert's syndrome; Cardiac ejection fraction ≥ 50%, echocardiography confirmed centropericardial effusion, and ECG showed no clinically significant abnormal findings.

• There was no clinically significant pleural effusion. Baseline blood oxygen saturation under indoor ventilation was \> 92%.

⁃ The serum pregnancy test results of fertile women must be negative (women who have undergone surgical sterilization or at least 2 years after menopause are considered to be infertile).