Allogeneic bone marrow transplantation for juvenile myelomonocytic leukemia: a single center experience of 23 patients

Juvenile myelomonocytic leukemia ( JMML) is a childhood leukemia for which allogeneic BMT is the only curative therapy. At our pediatric stem cell transplantation unit, we performed 26 BMTs in 23 children ( age 0.5 - 12.7 years). Conditioning was CY/ TBI based ( 1980 - 1996, n = 14) or BU/ CY/ melphalan based ( 1996 - 2001, n = 9). Donors were HLA- identical siblings ( n = 11), unrelated volunteers ( n = 9) or mismatched family members ( n = 3). A total of 10 patients survive in CR ( median follow- up 6.8 years, range 3.1 - 22.2 years). Relapse or persistent disease was observed in eight and two patients, respectively. Nine of these patients died, one achieved a second remission following acute nonlymphatic leukemia chemotherapy ( duration to date 5.3 years). Transplant-related mortality occurred in four patients. Overall survival at 5 and 10 years was 43.5%. Using T- cell-depleted, one- antigen mismatched unrelated donors was the only significant adverse factor associated with relapse in multivariate analysis ( P = 0.039, hazard ratio 4.9). Together with a trend towards less relapse in patients with graft- versus- host- disease and in patients transplanted with matched unrelated donors, this suggests a graft- versus-leukemia effect of allogeneic BMT in JMML.