This is an open, single-arm, clinical study to evaluate efficacy and safety of anti CD7 CAR-T cell in the treatment of CD7 Positive acute leukemia or mixed lineage leukemia except those who are diagnosed with T-ALL/T-LBL

The CARs consist of an anti-CD7 VHHs, a portion of the human CD137（4-1BB） molecule, and the intracellular component of the human CD3ζ molecule. Prior to CAR-T cell infusion, the patients will be subjected to preconditioning treatment. After CAR-T cell infusion, the patients will be evaluated for adverse reactions and efficacy.

The Main research objectives:

To evaluate the safety and efficacy of CD7 CAR-T cells in patients with CD7 Positive acute leukemia or mixed lineage leukemia except those who are diagnosed with T-ALL/T-LBL

The Secondary research objectives:

To investigate the cytokinetic characteristics of CD7 CAR-T cells in patients with CD7 Positive acute leukemia or mixed lineage leukemia except those who are diagnosed with T-ALL/T-LBL

Inclusion Criteria:

1. Diagnosis of refractory or relapsed CD7+ acute myeloid leukemia or mixed lineage leukemia was made according to the NCCN 2019.V2 guideline. Refractory AML is defined as a patient who has failed to achieve complete remission after induction therapy. Relapsed AML is defined as the reappearance of blasts (5%) in either peripheral blood or bone marrow. Patient diagnosed with AML should be treated and whose disease failed with at least 2 prior lines of therapies. Patients whose tumor burden ≥5% blasts, or who have persistent positive minimal residual disease (MRD), or have reappearance of extramedullary lesions are also considered eligible;
2. CD7+ expression on tumor cells (CD7 positive blasts ≥50% by flow cytometry);
3. Life expectancy greater than 12 weeks;
4. KPS or Lansky score≥60;
5. HGB≥70g/L (can be transfused);
6. oxygen saturation of blood>90%;
7. Total bilirubin (TBil)≤3 × upper limit normal, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 5×upper limit of normal;
8. Informed consent explained to, understood by and signed by patient/guardian

Exclusion Criteria:

1. Any of the following cardiac criteria: Atrial fibrillation/flutter; Myocardial infarction within the last 12 months; Prolonged QT syndrome or secondary prolonged QT, per investigator discretion. Cardiac echocardiography with LVSF (left ventricular shortening fraction)<30% or LVEF(left ventricular ejection fraction)<50%; or clinically significant pericardial effusion. Cardiac dysfunction NYHA(New York Heart Association) III or IV (Confirmation of absence of these conditions on echocardiogram within 12 months of treatment);
2. Has an active GvHD;
3. Has a history of severe pulmonary function damaging;
4. With other tumors which is/are in advanced malignant and has/have systemic metastasis;
5. Severe or persistent infection that cannot be effectively controlled；
6. Merging severe autoimmune diseases or immunodeficiency disease;
7. Patients with active hepatitis B or hepatitis C([HBVDNA+]or [HCVRNA+]);
8. Patients with HIV infection or syphilis infection;
9. Has a history of serious allergies on Biological products (including antibiotics);
10. Clinically significant viral infection or uncontrolled viral reactivation of EBV(Epstein-Barr virus), CMV(cytomegalovirus), ADV(adenovirus), BK-virus, or HHV(human herpesvirus)-6;
11. Presence of symptomatic disorders of the central nervous system, which include but not limited to uncontrolled epilepsy, cerebrovascular ischemia/hemorrhage, dementia, and cerebellar disease, etc.;
12. Have received transplant treatment for less than 6 months in prior to enrollment;
13. Being pregnant and lactating or having pregnancy within 12 months;
14. Any situations that the researchers believe will increase the risks for the subject or affect the results of the study