Promising approach for aggressive NK cell leukaemia with allogeneic haematopoietic cell transplantation

Objectives: Aggressive natural killer cell leukaemia (ANKL) is a malignant disorder of mature NK cells with a poor prognosis, for which no effective therapeutic approach has been established. We investigated the role of allogeneic haematopoietic cell transplantion (allo-HCT) in ANKL. Patients and methods: Three patients with ANKL received allo-HCT and seven did not. Epstein-Barr virus (EBV) viral load (VL) of the whole blood was measured with real-time quantitative polymerase chain reaction. Results: We transplanted three patients using a myeloablative conditioning regimen with human leucocyte antigen (HLA) two-loci mismatched cord blood (n=2), or HLA-matched sibling bone marrow (n=1). In one patient, a second transplantation from the haploidentical mother was also performed at relapse. No patients were in complete remission (CR) at the time of conditioning. After allo-HCT, all three achieved and maintained CR. One died from sepsis and the other relapsed, received the second transplantation and achieved a second CR. EBV VL was quite high in all three at presentation and its significant reduction was observed after allo-HCT. Although their backgrounds were not different from those without allo-HCT, patients with allo-HCT had a better outcome. Conclusion: Allo-HCT might be a promising therapy for ANKL with curative potential.