MED14-HOXA9 rearrangement in an adult patient with T/M mixed-phenotype acute leukemia

We performed transcriptome sequencing in an adult patient of MPAL. Our analysis identified a second instance of a recurrent MED14-HOXA9 chimeric gene resulting from the in-frame fusion of exon 23 of MED14 and exon 1 of HOXA9, the first in an adult patient. The MED14-HOXA9 fusion gene was found in both the diagnostic and relapse blasts with reverse transcription-polymerase chain reaction (RT-PCR) and Sanger sequencing. The patient received combined conventional chemotherapy but suffered relapse at 11 months and died of disease progression one year after the initial diagnosis. Our data confirm that MED14-HOXA9 is a cryptic recurrent aberration in T/M MPAL, which might indicate an aggressive clinical course and inferior outcome after conventional chemotherapy. Further studies will be carried out to reveal the effects of the MED14-HOXA9 fusion on the differentiation and proliferation of leukemia stem cells, as well as suitable treatment strategies for this emerging entity.