Predicting Survival after Allogeneic Hematopoietic Cell Transplantation in Myelofibrosis: Performance of the Myelofibrosis Transplant Scoring System (MTSS) and Development of a New Prognostic Model: Prognostication in myelofibrosis

Accurate prognostic tools are crucial to assess the risk/benefit ratio of allogeneic hematopoietic cell transplantation (allo-HCT) in myelofibrosis (MF) patients. We aimed to evaluate the performance of the Myelofibrosis Transplant Scoring System (MTSS) and identify risk factors for survival in a multicenter series of 197 MF patients undergoing allo-HCT. After a median follow-up of 3.1 years, 47% of patients had died, and the estimated 5-year survival rate was 51%. Projected 5-year risk of non-relapse mortality and relapse incidence was 30% and 20%, respectively. Factors independently associated with increased mortality were a Hematopoietic Cell Transplantation-specific Comorbidity Index (HCT-CI) = 3 and receiving a graft from an HLA-mismatched unrelated donor or cord blood, whereas post-transplant cyclophosphamide (PT-Cy) was associated with improved survival. Donor type was the only parameter included in MTSS model with independent prognostic value for survival. According to the MTSS, 3-year survival was 62%, 66%, 37%, and 17% for low, intermediate, high, and very high risk groups, respectively. By pooling together the low and intermediate risk groups, and the high and very high risk groups, we pinpointed two categories: standard risk and high risk (25% of the series). Three-year survival was 62% in standard risk and 25% in high risk categories (P