Infusion of Alloreactive nk Cells for Mrd-positive Aml Patients

This is a interventional, transplantation study. The procedure under study is the infusion of alloreactive NK cells in adult AML patients, eligible for ASCT, who achieved CR after conventional chemotherapy, but harbor MRD-positivity. Haploidentical KIR-L mismatched donors will be included if present at least one allele mismatch at a class I locus among the following ones: HLA-C alleles with Asn77-Lys80, HLA-C alleles with Ser77-Asn80, HLA-Bw4 alleles. KIR-L mismatched donor alloreactive NK cell repertoire will be evaluated in order to determine the functional cell dose to be used for NK cell collection. Phenotypical analysis of KIRs will be correlated to functional tests. NK cells will be selected from a steady-state large volume leukapheresis product from a suitable haploidentical KIR-ligand incompatible donor. NK cell purification will be performed if the donor leukapheresis product contains at least 10x106 NK cells/Kg. Immunomagnetic enrichment of NK cells will follow two subsequent steps: 1) depletion of CD3+ T cells followed by 2) positive selection of CD56+ NK cells. Patients will receive immunosuppressive chemotherapy, fludarabine (Flu) 25 mg/mq/ from day -5 to -3 and cyclophosphamide (Cy) 2 g/mq on day -2 (Flu/Cy). Two days after Cy administration, patients will be infused intravenously with a single dose of cryopreserved NK cells (day 0), which will be followed by subcutaneous administration of IL-2 (10 x 106 IU/day, 3 times weekly) for 2 weeks (6 doses total). PB samples will also be collected for biological studies. In particular, PB samples will be collected for molecular assessment of microchimerism and tracking of haploidentical NK cells for 30 days, immunophenotype studies, alloreactive NK cells cloning and functional assays (cytotoxicity). Enrolled patients will be followed up for at least 12 months after NK cell infusion.