Changing Patterns, And Clinical Correlates, Of Mutations In Patients With Myelofibrosis Over Treatment With Ruxolitinib Or Hydroxyurea

Background. About half of patients (pts) with primary (PMF) and post-polycythemia vera/essential thrombocythemia MF (PPV/PET-MF) lose clinical response over prolonged treatment (3y+) with ruxolitinib. Both driver (JAK2, MPL, CALR) and non-driver mutations lack predictive power for the short-term (1y) response (Guglielmelli P, Blood 2015) although pts with >3 mutations are less likely to respond to ruxolitinib (Patel K, Blood 2016). Despite some reductions of Variant Allele Frequency (VAF) of driver mutations, molecular remissions induced by ruxolitinib are exceptional.