Pathologic Spectrum and Molecular Landscape of Myeloid Disorders Harboring SF3B1 Mutations

Objectives: SF3B1 mutations are the most common mutations in myelodysplastic syndromes (MDS). The International Working Group for the Prognosis of MDS (IWG-PM) recently proposed SF3B1-mutant MDS (SF3B1-mut-MDS) as a distinct disease subtype. We evaluated the spectrum and molecular landscape of SF3B1-mutated myeloid disorders and assessed the prognostication in MDS harboring SF3B1 mutations (MDS-SF3B1). Methods: Cases were selected by retrospective review. Clinical course and laboratory and clinical findings were collected by chart review. SF3B1-mut-MDS was classified following IWG-PM criteria. Results: SF3B1 mutations were identified in 75 of 955 patients, encompassing a full spectrum of myeloid disorders. In MDS-SF3B1, Revised International Prognostic Scoring System (IPSS-R) score greater than 3 and transcription factor (TF) comutations were adverse prognostic markers by both univariate and multivariate analyses. We confirmed the favorable outcome of IWG-PM-defined SF3B1-mut-MDS. Interestingly, it did not show sharp prognostic differentiation within MDS-SF3B1. Conclusions: SF3B1 mutations occur in the full spectrum of myeloid disorders. We independently validated the favorable prognostication of IWG-PM-defined SF3B1-mut-MDS. However it may not provide sharp prognostication within MDS-SF3B1 where IPSS-R and TF comutations were prognostic-informative. Larger cohort studies are warranted to verify these findings and refine MDS-SF3B1 prognostication.