JAK2V617F mutation persists in blasts and mature cells of transformed JAK2V617F-positive-myeloproliferative neoplasia: a European Leukemia Net (ENL) study.

Transformation to acute myeloid leukemia (AML) is a known complication of myeloproliferative neoplasia (MPN). Recent studies reported the high incidence (53%) of JAK2 negative blasts from transformed JAK2V617F-MPN. We collected, by cell sorting, blast cells, and mature cells (GRA) from total bone marrow (BM) of 34 patients newly diagnosed of secondary AML. At MPN diagnosis (PMF n 5 18; PV n 5 9; ET n 5 7), JAK2 was mutated in 22 of 34 patients. Twenty of 22 JAK2V617F-MPN (91%) maintained the mutation in blasts and GRA after leukemic switch, while in 2 of 22 patients the selected compartments lost the mutation. Surprisingly, we also found the first case of JAK2V617F-AML from a wild type (WT)-MPN. In contrast to the previous study, we conclude that JAK2V617F-MPN yields rarely (9%) a JAK2WT-AML and any JAK2-status modification/persistence involves always the entire BM during leukemic transformation.