Conditioning regimen
The conditioning regimen was initiated at day 7 from NK-cell infusion and consisted of one infusion of fludarabine (f; 25 mg/m2) per day for the first 4 days (days − 7 to -4) followed by one infusion of cyclophosphamide (c; 25 mg/kg) per day (days-3 to-2). Fresh PB-NK cells were infused on day 0. The remaining PB-NK cells were cryopreserved (40% Plasmalyte, 50% human AB serum, 10% dimethyl sulfoxide) and thawed, washed, and infused on days + 7 (Fig. 