Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only curative treatment for patients with advanced myelodysplastic syndrome (MDS) and secondary acute myelogenous leukemia (sAML), but in the absence of prospective trials the impact of pretransplant cytoreduction is controversially discussed. We retrospectively analyzed the outcome of 165 patients with MDS and excess blasts (n = 126, 76%) and sAML (n = 39, 24%) according to a pretransplant strategy. Sixty-seven patients (41%) were directly transplanted (upfront group), whereas 98 patients (59%) had received pretransplant cytoreductive treatment (induction chemotherapy [CTX], n = 64; hypomethylating agents [HMAs], n = 34) resulting in a significantly higher complete remission rate in the CTX group (59% versus HMA 18%, P < .0001). Estimated rates of 5-year overall survival (OS) and relapse-free survival (RFS) for the entire group were 54% and 39%, respectively. The 5-year OS rates of the upfront, CTX, and HMA groups were 61%, 50%, and 45%, respectively (P = .116), whereas RFS rates were 38%, 41%, and 38% (P = .926). Cumulative incidence of relapse (CIR) and nonrelapse mortality (NRM) did not differ between treatment groups. In the upfront group no difference regarding OS and RFS was seen with respect to pretransplant blast count (>10% versus <10%). In multivariate analyses type of pretransplant strategy did not have an effect on OS, RFS, CIR, and NRM, whereas cytogenetics (OS, RFS, CIR), reduced-intensity conditioning (OS, RFS, CIR), and an unrelated donor (RFS, CIR) were identified as negative predictors. When compared with the upfront group, 5-year OS was significantly lower in patients with CTX-refractory disease (34% versus 64%, P = .0346) and by clear trend in HMA nonresponders (42% versus 61%, P = .073), whereas RFS did not differ significantly. In further support of the concept, that pretransplant therapy may favor the selection of resistant clones, patients in the upfront group had a higher likelihood to respond to HMAs as salvage therapy for relapse in comparison with pretreated patients (complete remission, 58% versus 10%; P = .0005) and a higher 2-year OS rate after relapse (59% versus 19%, P = .0001). These data suggest that an upfront transplant strategy is at least not inferior to pretransplant cytoreduction and may be augmented by HMAs + donor lymphocyte infusion salvage therapy in case of relapse after allo-HSCT.
