Allogeneic Transplantation in the rare disease MDS/MPN with Neutrophilia: Age and Disease Burden Determine Outcome

, is a rare hematologic malignancy with poor prognosis. Allogeneic hematopoietic stem cell transplantation (allo-HCT) is the only curative treatment, but prognostic factors for posttransplant outcomes are poorly defined. This retrospective multicenter analysis included 85 patients allografted over a 30 year period at eight German centers, representing the largest cohort reported so far. Uni- and multivariable analyses were performed to identify prognostic factors for posttransplant outcome. Endpoints were overall survival (OS), relapse-free survival (RFS), cumulative incidence of relapse (CIR) and non-relapse mortality (NRM). After a median follow-up of 7.6 years, 5-year OS, RFS, CIR and NRM were 47%, 37%, 32% and 29% respectively. Age ≥50 years and bone marrow (BM) blasts ≥5% were associated with inferior OS and RFS in univariable analyses, while hemoglobin <8 g/dL adversely affected RFS. In multivariable analysis, younger age remained an independent predictor for improved OS and RFS, while higher Hb level were associated with superior RFS. Additionally, EZH2 and TET2 mutations were linked to increased relapse risk and inferior RFS, while TET2 mutations also negatively impacted OS. Although limited by its retrospective character, small sample size and incomplete molecular data, this study shows that long-term survival after allo-HCT is achievable in patients with MDS/MPN with Neutrophilia, particularly in younger individuals with low disease burden. However, relapse and NRM remain major challenges underscoring the need for optimized post-transplant strategies.