The purpose of this study is to estimate the efficacy of immunotherapy with ex vivo expanded haploidentical NK cells for children/young adults with primary high risk or refractory AML and relapsed AML.

Immunotherapy with NK cells may improve the treatment results in AML. For better efficiency high cell doses or several infusions of NK cells are required. For this purpose, donor NK cells are expanded in the presence of feeder K562-mbIL21-41BBL cell line.

For patients with high-risk primary AML a cycle of immunotherapy includes chemotherapy (HD-ARA-C+IDA) followed by three doses of NK cells infusion.

For patients with refractory/relapsed AML a cycle of immunotherapy includes chemotherapy (FLAG - fludarabine, cytarabine, G-CSF) followed by three doses of NK cells infusion.

A 2nd cycle of therapy may be administered if a recipient continues to meet the eligibility criteria.

Inclusion Criteria:

Patients:

• primary high risk AML
• primary refractory AML
• relapsed AML
• Karnofsky or Lansky performance scale greater or equal to 70
• written informed consent

Donors:

• haploidentical family donor
• donor suitable for cell donation and apheresis according to standard criteria
• written informed consent

Exclusion Criteria:

Patients:

• uncontrolled infection
• severe hepatic dysfunction: SGOT or SCPT >=5x upper limit of normal for age
• positive serology for human immunodeficiency virus (HIV)

Donors:

• pregnancy
• positive serology for HIV, hepatitis B or C