Allogeneic Hematopoietic Stem Cell Transplant (HSCT)

Allogeneic HSCT is the only potentially curative treatment for MDS. Retrospective data suggest cure rates in selected patients ranging from 30% to 60%; outcomes varied with IPSS score at time of transplant, with inferior survival in patients with higher IPSS scores.[32][Level of evidence C3] The role of cytoreductive therapy in reducing the blast percentage before HSCT remains uncertain. Outcomes may not be as good for patients with treatment-related MDS (5-year disease-free survival rate of 8% to 30%).[33]

Although HSCT represents the only treatment modality with curative potential, the relatively high morbidity and mortality of this approach limits its use. A decision analysis predating approval of azacitidine, in patients with a median age younger than 50 years, suggested optimal survival when transplant was delayed until disease progression for lower-risk patients but implemented at diagnosis for higher-risk patients.[34]

Allogeneic stem cell transplant with reduced-intensity conditioning (RIC) has extended transplant as a possible modality for treatment of older patients.[35] In a retrospective analysis of 1,333 patients aged 50 years or older (median, 56 years) who underwent allogeneic transplants for MDS using HLA-matched sibling and unrelated donors, 62% of the patients received RIC HSCT, and the others received standard-dose HSCT. On multivariate analysis, use of RIC and advanced disease stage at transplant were associated with increased relapse (hazard ratio [HR] of 1.44 and 1.51, respectively).[35][Level of evidence C3] The predictors of non-relapse mortality included advanced disease stage (HR, 1.43), use of an unrelated donor, and standard-dose HSCT (HR, 1.27). The 4-year OS rate was similar in both groups (30% after myeloablative conditioning vs. 32% in RIC.[35]