Abstract
The patterns of low-risk myelodysplastic syndrome (MDS) progression and the clinical and molecular features of those patterns have not been well described. We divided our low-risk (LR) MDS patients (N=1,914) into 4 cohorts: 1) patients who remained LR-MDS (LR-LR; N=1,300; 68%), 2) patients who progressed from LR to high-risk (HR) MDS (LR-HR) without transformation into acute myeloid leukemia (AML) (N=317; 16.5%), 3) patients who progressed from LR to HR MDS and then AML (LR-HR-AML; N=124; 6.5%), and 4) patients who progressed from LR MDS directly to AML (LR-AML; N=173; 9%). Risk factors for progression included: male gender, low absolute neutrophil count (ANC), low platelet count, high bone marrow (BM) blasts, ferritin >1000 mcg/L, albumin <3.5 g/dL, multi-lineage dysplasia (MLD), and lack of ring sideroblasts. Among patients with marked BM fibrosis (N=49), 18% progressed directly to AML. Somatic mutations (SM) associated with an increased risk of direct or indirect AML progression included SRSF2 and NRAS. SM in IDH1, IDH2 and NPM1 were more common in patients with direct AML transformation. SM associated with progression to higher risk disease only, without AML transformation, were ASXL1, TP53, RUNX1, and CBL. SF3B1 mutation was associated with less progression. About 171 patients (13.1% of all LR-LR patients) died within two years of diagnosis of LR-MDS without disease progression. Among the 61 cases with documented cause of death, 18 patients (29.5%) died from cytopenia and MDS-related complications. Identifying patterns of disease progression of LR MDS patients and their predictive factors will be crucial to be able to tailor therapy accordingly.