Multicenter study evaluating the impact of hypomethylating agents as bridging therapy to hematopoietic stem cell transplantation in myelodysplastic syndromes.

Allogeneic hematopoietic stem cell transplantation (alloSCT) is currently the only curative treatment modality for myelodysplastic syndromes (MDS). The treatment paradigm for MDS has changed in recent years with the introduction of hypomethylating agents (HMAs). The present retrospective multicenter study was designed to assess the effects of pre-transplant HMA on transplant outcome and determine which patients would benefit most from this therapy. A total of 109 patients who received alloSCT at one of five institutions between 2007 and 2010 were enrolled in this study regardless of pre-transplant HMA therapy. 81 of the 109 patients enrolled were treated with HMA prior to alloSCT. 28 patients received alloSCT without HMA bridging. The distributions of WHO classification groups and IPSS scores were similar between the two groups (P = 0.752 and P = 0.265, respectively). Pre-transplant HMA did not affect OS (P = 0.244), and there were no differences in response to HMA therapy within the HMA-treated group. The cumulative incidence of NRM was not significantly different between the two groups (P = 0.500). However, for patients with a high blast count (>5 % of bone marrow at the time of diagnosis), pre-transplant HMA therapy had a NRM benefit (83.3 vs. 48.6 %, P = 0.014).