Safety of Expanded Haploidentical Natural Killer Cells for Leukemia

Immunotherapy with natural killer (NK) cells may improve the results of treatment for patients with cancer. However, for better efficiency high doses of NK cells are required. For this purpose, NK cells were expanded in the presence of feeder K562 cells gene-modified for expression 4-1BBL and membrane bound IL-21. In the result of expansion, large number of activated NK cells are obtained. Protocol of immunotherapy includes conditioning (fludarabine + cyclophosphamide or any other protocol of chemotherapy) followed by expanded NK cells intravenous infusion. To sustain proliferation of donor NK cells in vivo patients receive 6 doses of Il-2 every second day. 10 patients will be enrolled in phase I to test different doses of NK cells: 20, 50, 70, 100 and \>100 x 10\^6/kg.