Kawamura K, et al. – This study entailed the comparison of conditioning with fludarabine/busulfan and fludarabine/melphalan in allogeneic transplant recipients 50 years or older. A worse non-relapse mortality (NRM) largely offset the lower rates of relapse in the FB4 and FM140 groups. Findings suggested a potential association between FM140 and better overall survival (OS) in patients with high-risk acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS).

• 1607 patients aged 50 years or older with acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), or myelodysplastic syndrome (MDS) who underwent allo-HCT using fludarabine/busulfan (FB) or fludarabine/melphalan (FM) between 2007 and 2014, were examined.
• The clinical outcomes among FB2 (busulfan at 6.4 mg/kg iv, n=463), FB4 (busulfan at 12.8 mg/kg iv, n=721), and FM140 (melphalan at 140 mg/m2, n=423), were compared.
• As compared to the FB2 group, the non-relapse mortality (NRM) rates in the FB4 and FM140 groups were higher (hazard ratio (HR) 1.63, p<0.001 and HR 1.71, p<0.001).
• Results revealed lower relapse rates in the FB4 and FM140 groups than that in the FB2 group (HR 0.73, p=0.011 and HR 0.56, p<0.001)
• No significant differences were noticed in overall survival (OS) among the FB2, FB4, and FM140 groups.
• According to results, the 3-year OS in patients with high-risk AML and MDS in the FM140 group (37.0% and 60.2%) were superior to those in the FB2 group (24.4% and 45.5%) and the FB4 group (24.6% and 40.6%) (p=0.016 and p=0.023).
• In addition, no differences were observed in OS in the other patients among the 3 groups.