This is a prospective,open-label, single center and single arm phase 1/2 study to evaluate the efficacy and safety of T cells expressing humanized CD7 chimeric antigen receptors treatment for patients with refractory/relapsed CD7 positive acute leukemia.

The patients will receive infusion of CAR T-cells targeting CD7 to confirm the safety and efficacy of CD7 CAR T-Cells in CD7+ relapsed or refractory acute leukemia.

Inclusion Criteria:

1. Diagnosed CD7 positive relapsed/refractory acute leukemia.
2. Age 12-65 years.
3. Eastern Cooperative Oncology Group (ECOG) score 0-2.
4. CD7 on leukemia is >30% positive detected with flow cytometry.
5. Patients with left ventricular ejection fraction ≥ 0.5 by echocardiography or grade I/II cardiovascular dysfunction according to the New York Heart Association Classification.
6. Patients with aspartate aminotransferase or glutamic-pyruvic transaminase > 3x upper limit of normal or bilirubin > 2.0 mg/dL.

Exclusion Criteria:

1. Patients are pregnant or lactating
2. Patients with congenital immunodeficiency.
3. Patients with central nervous system leukemia.
4. Patients with uncontrolled active infection.
5. Patients with active hepatitis B or hepatitis C infection.
6. Patients with HIV infection.
7. Patients with atrial or venous thrombosis or embolism.
8. Patients with myo-infarction or severe arrythmia in the recent 6 months.
9. Other comorbidities that investigators considered not suitable for this study.