Outcomes in patients undergoing hematopoietic stem cell transplantation for myelodysplastic syndromes

Hematopoietic stem cell transplantation [HSCT] is the only curative option for patients with myelodysplastic syndromes [MDS]. Between 1991 and 2021, 154 patients [high risk, 86; low risk, 68] including 22 children underwent HSCT with a median age of 36 years. Conditioning regimens were myeloablative [n=97] and reduced intensity [n=53]. Donors were human leucocyte antigen (HLA)-matched related donors (MRDs) in 113 and alternate donors in 41. The graft source was peripheral blood stem cells in 92%. Engraftment occurred in 126 [81.9%] at a median of 15 days while 20 [12.9%] died before engraftment and eight [5.2%] had primary graft failure. Sinusoidal obstruction syndrome was seen in 27 [17.5%]. Grade 2-4 acute graft versus host disease [GVHD] occurred in 46.3% while Grade 3-4 GVHD was seen in 34.9% and the incidence of chronic GVHD was 69.4%. Bacterial infections occurred in 38 (24.6%) while viral infections were seen in 31 [20.1%], mainly cytomegalovirus, and invasive fungal disease in 17.5%. At a median of 33 months, 65 patients were alive; 14 (9.1%) had disease relapse, and 10 (6.5%) had secondary graft failure. The five-year overall survival (OS) (time from allogenic HSCT to death due to any cause) and event-free survival (time from allogenic HSCT to relapse/ progression of disease or death) were 41.69±4.2% and 40.8±4.4%, respectively. The five-year OS was significantly better in children [71%]. Outcomes were better with MRDs [45%] compared to alternate donors [29%; p=0.035]. Outcomes of HLA-MRD transplants have been improving; 44% for 1990 - 2000, 35% for 2001 - 2010, and 51% for 2011 - 2021. On multivariate analysis, age (adolescents and young adults [hazard ratio (HR) 2.7, p=0.021] and older adult age group [HR 3.6, p=0.006]), minor blood group mismatch [HR 2.0, p=0.028], bidirectional blood group mismatch [HR 2.6, p=0.010], and haploidentical stem cell donor [HR 2.2, p=0.007] were associated with poorer OS. In conclusion, outcomes of HSCT for MDS are reasonable among matched sibling donors but outcomes in alternate donors require improvement. Strategies to reduce GVHD and infections should be explored.