"LANK-2": Activated and Expanded NK Cell Immunotherapy Together With Salvage Chemotherapy in Children, Adolescents and Young Adults With Relapsed or Refractary Acute Leukemia

Inclusion Criteria: 1. Patients between 0 and 23 years of age with diagnosis of acute lymphoblastic leukemia, in second relapse situation, posttransplant relapse or refractary, or 2. Patients between 0 and 23 years of age with diagnosis of acute myeloblastic leukemia, relapsed or refractary. (Patient must meet inclusion criteria 1 or 2) 3. Lansky index \> 60% 4. Mild (\<2) functional organs alteration (hepatic, renal, respiratory) according to National Cancer Institute criteria (NCI CTCAE v4). 5. Left ventricular ejection fraction \> 39% 6. To grant informed consent in accordance with the current legal regulations. 7. Presence of a compatible haploidentical donor (father or mother or brother). Exclusion Criteria: 1. Patients with history of bad therapeutical compliance 2. Patients not valid after psycho-social evaluation 3. Positive HIV serology