Leukemia-free survival of patients during the chronic phase according to the presence of additional mutations. Kaplan-Meier curve of leukemia-free survival for patients in the chronic phase (n = 109; 80 patients from the control group and 29 patients evolving to leukemic transformation) after propensity score adjustment according to the presence of at least 1 additional mutation, considering all additional mutations (A) or all additional mutations except in TET2 (B).