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This study examines the response to dexamethasone-doxorubicin-vincristine (DAV) therapy, followed by conditioning regimen and autologous stem cells transplantation (ASCT) in patients with multiple myeloma in relation with the presence of polymorphisms in genes involved in drug metabolism (GSTP1) and DNA synthesis (TYMS). GSTP1 G313G genotype (OR=5.49; 95% CI, 1.3-22.5, p=0.02) and TYMS A227A genotype (OR=3.41; 95% CI, 1.3-8.9, p=0.01) resulted significantly associated with a poor response following chemotherapy and the risk increased for the combined genotype (OR=13.54; 95% CI, 2.0-91.3, p=0.01). TYMS T157T genotype was significantly associated with a poor response after ASCT (OR=4.60; 95% CI, 1.2-16.9, p=0.02). Pre-therapeutic individual determination of the GSTP1 and TYMS polymorphisms could help in choosing the most appropriate protocol.

The multidrug resistance gene (MDR1) has been reported to be an additional prognostic factor in acute myeloid leukaemia patients. This study evaluated the prognostic role of MDR1 in the outcome of 115 multiple myeloma patients treated with DAV (dexamethasone, doxorubicin [adryamicin] and vincristine) regimen followed by autologous transplantation. In particular, when investigating the C3435T polymorphism, a prognostic value of MDR1 genotypes for overall survival (OS) was observed. Our data suggested a longer OS for patients with C/T and T/T genotypes (log-rank test, P = 0.02) compared with patients with C/C genotype.

Patients with multiple myeloma (MM) have increased bone marrow (BM) angiogenesis; however, the proangiogenic properties of myeloma cells and the mechanisms of MM-induced angiogenesis are not completely clarified. The angiopoietin system has been identified as critical in the regulation of vessel formation. In this study we have demonstrated that myeloma cells express several proangiogenic factors, and, in particular, we found that angiopoietin-1 (Ang-1), but not its antagonist Ang-2, was expressed by several human myeloma cell lines (HMCLs) at the mRNA and the protein levels. In a transwell coculture system, we observed that myeloma cells up-regulated the Ang-1 receptor Tie2 in human BM endothelial cells. Moreover, in an experimental model of angiogenesis, the conditioned medium of HMCLs significantly stimulated vessel formation compared with control or vascular endothelial growth factor (VEGF) treatment. The presence of anti-Tie2 blocking antibody completely blunted the proangiogenic effect of XG-6. Finally, our in vitro results were supported by the in vivo finding of Ang-1, but not Ang-2, mRNA and protein expression in purified MM cells obtained from approximately 47% of patients and by high BM angiogenesis in patients with MM positive for Ang-1, suggesting that the angiopoietin system could be involved, at least in part, in MM-induced angiogenesis.