Three atypical BCR/ABL transcripts detected simultaneously in a Philadelphia-positive acute lymphoblastic leukemia patient showing resistance to tyrosine kinase inhibitors.

The Philadelphia (Ph) chromosome with a BCR/ABL fusion gene is a characteristic feature of chronic myeloid leukemia (CML) and partial acute lymphoblastic leukemia (ALL) patients, with different breakpoints of the BCR and ABL genes. Here, we report the case of a Ph-positive ALL patient with poor prognosis in whom simultaneous different BCR/ABL transcripts named e1a3, e1a4, and e1a5 were detected by RNA-seq analysis but not traditional RT-PCR. To our knowledge, this is the first report to describe coexistence of different atypical BCR-ABL transcripts in the same patient and that traditional TKI therapy may not overcome the poor prognosis. This finding will bring new challenges in diagnosis and monitoring for minimal residual disease.