Clonal architecture of AML with mutated NPM1 at relapse. (A) Change in the ELN risk classification at relapse. (B) Mutational evolution, including stability, gain, or loss of mutations at relapse. N is the number of patients with the corresponding mutation at diagnosis among those evaluable by mutational analysis performed at diagnosis and at the time of relapse. The percentages for stability and loss were calculated as the number of patients with mutations that persisted or were lost at relapse divided by patients with mutations in the corresponding gene present at diagnosis. Percentage gain was calculated as the number of patients with mutations acquired at relapse divided by the number of patients without mutations in the corresponding gene at diagnosis. (C-D) Impact of NPM1c loss at relapse on relapse-free survival and overall survival. ∗Two of the 6 patients who lost NPM1c at relapse underwent mutational analysis at diagnosis before referral to our center.