Synergistic Effect of Concurrent High Molecular Risk Mutations and Lower JAK2 Mutant Variant Allele Frequencies on Prognosis in Patients with Myelofibrosis-insights from a Multicenter Study

In addition to high-molecular risk (HMR) mutations (ASXL1, EZH2, SRSF2, IDH, and U2AF1), lower JAK2V617F variant allele frequencies (VAF) have been demonstrated to be associated with poor prognosis of myelofibrosis (MF) patients. Nevertheless, the relationship between JAK2V617F VAF and HMR mutations remains inconclusive. To address this, we analyzed the mutation status of 54 myeloid neoplasm-relevant genes using targeted next-generation sequencing in 124 MF patients. Three cohorts from multiple international centers were analyzed for external validation. Among JAK2-mutated patients, the presence of HMR mutations drove poor prognosis in patients with lower JAK2V617F VAF but not in those with higher JAK2V617F VAF. Survival analyses showed consistent results across validation cohorts. In multivariable analysis, concurrent HMR and a lower JAK2V617F VAF was identified as an independent adverse prognostic factor for survival, irrespective of age, MIPSS70, MIPSS70 + v2, and GIPSS risk groups. Mutation co-occurrence tests revealed no shared mutational pattern over different cohorts, excluding potential confounding effect from other concurrent mutations. Importantly, the integration of HMR/JAK2V617F VAF (≤50%) status significantly enhanced existing prognostic models, as evidenced by higher c-indexes and time-dependent ROC analyses. Single-cell studies with sequential follow-ups are warranted to decipher the clonal evolution of MF and how it relates to JAK2V617F VAF dynamics.