BACKGROUND: We assessed the toxicity and feasibility of the three-alkylator combinations as conditioning regimens for allogeneic hemopoietic stem cell transplantation (HSCT) in 23 adult patients tilth acute leukemia.
METHODS: Sixteen patients were transplanted for acute myeloid leukemia, six for acute lymphoblastic leukemia, and one for myelodysplastic syndrome. Group A included thirteen cases of relapsed refractory, 2 relapsed after first HSCT and group B eight
patients in first complete remission or two in second complete remission. Eleven cases received G-CSF mobilized CD34+ allogeneic peripheral blood stem cells (PBSCs) in addition to bone marrow (BM) and three in vivo expanded BM by G-CSF and eight
unmanipulated BM and one from syngeneic BM after conditioned with busulfan, thiotepa and melphalan (n=14) or cyclophosphamide, thiotepa and melphalan(n=6) or TBI, melphalan and thiotepa (n=3).
RESULTS: Twelve of thirteen patients in group A patients engrafted successfully and only one patient fatted to achieve complete remission (CR). All patients in group B had successful engraftment. The median days reaching absolute neutrophil count (ANC)
more than 500/㎕ and platelet more than 30,000/㎕ in group A and group B were 13.4 days (7-22), 17.9days (9-40) and 16.3 days (10-21), 22.6 days (13-38), respectively. Acute graft vs host disease (GVHD) developed in both groups with the incidence of
seven (78%) for group A and slut (60%) for group B. The major regimen-related toxicity was mucositis with incidence of 95.7% (22/23). The disease free survival rate after HSCT with median follow-up of 161 days (31-283 days) and 101 days (22-163 days) in
each group were 24% and 62.5%, respectively.
CONCLUSION: Although the observation period is limited, this study shows that the combination of triple-alkylating regimens are tolerable as a preparative regimen for allogeneic HSCT for both high-risk and standard-risk leukemic patients. We need to
confirm effects of these regimens in prospective randomized-controlled studies in the future.

Keywords: Acute leukemia, Busulfan, Melphalan, Thiotepa, Cyclophosphamide, Allogeneic HSCT, PBSC, TBI