Initiating-clone analysis in patients with acute myeloid leukemia secondary to essential thrombocythemia.

Most of essential thrombocythemia (ET) patients have the clone harboring a mutation in one of the JAK2, CALR, or MPL gene, and these clones generally acquire additional mutations at transformation to acute myeloid leukemia (AML). However, the proliferation of triple-negative clones has sometimes been observed at AML transformation. To clarify the clonal evolution of ET to AML, we analyzed paired samples at ET and AML transformation in eight patients. We identified that JAK2-unmutated AML clones proliferated at AML transformation in three patients in whom the JAK2-mutated clone was dominant at ET. In two patients, TET2-mutated, but not JAK2-mutated, clones might be common initiating clones for ET and transformed AML. In a patient with JAK2-mutated ET, SMARCC2, UBR4, and ZNF143, but not JAK2, -mutated clones proliferated at AML transformation. Precise analysis using single-cell sorted CD34/CD38 fractions suggested that ET clone with JAK2-mutated and AML clone with TP53 mutation was derived from the common clone with these mutations. Although further study is required to clarify the biological significance of SMARCC2, UBR4, and ZNF143 mutations during disease progression of ET and AML transformation, the present results demonstrate the possibility of a common initial clone involved in both ET and transformed AML.