Anti-CD19 CAR-Engineered NK Cells in the Treatment of Relapsed/Refractory Acute Lymphoblastic Leukemia

Inclusion Criteria:

* Age ≥12 years in the single-dose exploration phase, age ≥3 years in the dose exploration phase, both sexes;
* Meet the diagnostic criteria for recurrent or refractory CD19 positive acute lymphoblastic leukemia.
* The main organs have good organ function.
* The estimated survival time is ≥12 weeks.
* Blood pregnancy tests for women of childbearing age are negative.
* The patient himself/herself , and/or his/her legal guardian, agree to participate in the trial and sign the informed consent form.

Exclusion Criteria:

* Central nervous system involvement；
* Simple extramedullary leukemia or simple extramedullary recurrence；
* Received hematopoietic stem cell transplantation within the last 3 months and had graft-versus-host disease (GVHD) in the last 2 weeks, requiring immunosuppressive agents；
* Treated with high-dose corticosteroids in the last 1 week；
* Allogeneic cell therapy, major surgery, and live or attenuated vaccine had been received within 4 weeks prior to CAR NK-CD19 infusion；
* Had received other antitumor therapy or had an uncontrolled infection within 2 weeks prior to CAR NK-CD19 infusion；
* Systemic steroids were used within 3 days before CAR NK-CD19 infusion；
* Toxicity caused by previous treatment do not fully recover or do not stabilize to grade 1；
* Concomitant autoimmune diseases, central nervous system diseases, other active malignancies, infectious diseases, severe cardiovascular diseases, etc；
* Known allergies to study drugs or drugs that may be used in the study；
* Other conditions determined by Investigator which are not suitable for participation in the study