MIPSS70: Mutation-Enhanced International Prognostic Score System for Transplantation-Age Patients With Primary Myelofibrosis

PurposeTo develop a prognostic system for transplantation-age patients with primary myelofibrosis (PMF) that integrates clinical, cytogenetic, and mutation data.Patients and MethodsThe study included 805 patients with PMF age ≤ 70 years recruited from multiple Italian centers and the Mayo Clinic (Rochester, MN), forming two independent learning and validation cohorts. A Cox multivariable model was used to select from among a list of 22 variables those that were predictive of overall survival (OS). Integrated clinical and genetic prognostic models with (MIPSS70-plus) or without (MIPSS70) cytogenetic information were developed.ResultsMultivariable analysis identified the following as significant risk factors for OS: hemoglobin 25 × 109/L, platelets < 100 × 109/L, circulating blasts ≥ 2%, bone marrow fibrosis grade ≥ 2, constitutional symptoms, absence of CALR type-1 mutation, presence of high–molecular risk mutation (ie, ASXL1, EZH2, SRSF2, IDH1/2), and presence of two or more high–m...