Two myeloid leukemia cases with rare <i>FLT3</i> fusions

Abstract

Genetic rearrangements involving <i>FLT3</i> are rare and only recently have been detected in myeloid/lymphoid neoplasms associated with eosinophilia (MLN-eos) and chronic myeloproliferative disorders. Here we report two cases with <i>FLT3</i> fusions in patients demonstrating mixed features of myelodysplastic/myeloproliferative neoplasms. In the first case, <i>FLT3</i> was fused with a new fusion partner <i>MYO18A</i> in a patient with marrow features most consistent with atypical chronic myeloid leukemia; the second case involving <i>ETV6</i>-<i>FLT3</i> fusion was observed in a case with bone marrow features most consistent with chronic myelomonocytic leukemia. Notably, we observed that samples from both patients demonstrated FLT3 inhibitor (quizartinib and sorafenib) sensitivity in ex vivo drug screening assay.