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Busulfan liver metabolism depends on glutathione, a crucial mediator of cellular and systemic stress. Here we investigated 40 polymorphisms at 27 loci involved in hepatic glutathione homeostasis, with the aim of testing their impact on the clinical outcome of 185 busulfan-conditioned allogeneic transplants. GSTA2 S112T serine allele homozygosity is an independent prognostic factor for poorer survival (RR=2.388), for increased any time- and 100-day transplant-related mortality (RR=4.912 and RR=5.185, respectively). The genotype also predicts a wider busulfan area under the concentration-time curve (1214.36±570.06 vs. 838.10±282.40 mMol*min) and higher post-transplant bilirubin serum levels (3.280±0.422 vs. 1.874+0.197 mg/dL). In vitro, busulfan elicits pro-inflammatory activation (increased NF-KappaB activity and interleukin-8 expression) in human hepatoma cells. At the same time, the drug down-regulates a variety of genes involved in bilirubin liver clearance: constitutive androstane receptor, multidrug resistance-associated protein, solute carrier organic anion transporters, and even GSTA2. It is worthy of note that GSTA2 also acts as an intra-hepatic bilirubin binding protein. These data underline the prognostic value of GSTA2 genetic variability in busulfan-conditioned allotransplants and suggest a patho-physiological model in which busulfan-induced inflammation leads to the impairment of post-transplant bilirubin metabolism.

Background and Objectives Peripheral blood stem cells (PBSC) following reduced intensity conditioning (RIC) are being increasingly used for allogeneic transplantation in multiple myeloma. The purpose of this study was to compare outcome of patients transplanted with either PBSC or bone marrow (BM) following RIC or myeloablative conditioning (MAC).Design and Methods Data from 1,667 patients who had received an allogeneic identical sibling donor transplant for multiple myeloma from 1994 to 2003 were analyzed. Comparisons were made between results of PBSC and BM transplants after conditioning with RIC or MAC.Results The engraftment rate was faster with PBSC than with BM (median: 14 and 18 days for neutrophils and 15 and 25 days for platelets respectively) irrespectively of whether RIC or MAC was used. The incidence of acute graft-versus-host disease (GVHD) did not differ significantly between the groups while chronic GVHD was more prevalent in PBSC recipients irrespectively of whether they had RIC or MAC. Non-relapse mortality did not differ between PBSC and BM recipients, but was significantly higher in those treated with MAC than in those given RIC irrespectively of the cell source. The relapse/progression rate did not differ between PBSC and BM recipients, but was significantly higher in those given RIC, irrespectively of the cell source. There was no significant difference in overall or progression-free survival between patients given PBSC or BM transplants.Interpretation and Conclusions Although transplantation of PBSC is associated with faster engraftment and more frequent chronic GVHD, overall survival, non-relapse mortality, relapse/progression and progression-free survival are similar to those following BM transplants. However both PBSC and BM transplants are associated with lower non-relapse mortality, lower response rate and higher relapse/progression if RIC is used instead of MAC.