AUTHOR=Di Giusto Sara , Toffoletti Eleonora , Cozzarolo Cinzia , Liani Tomas , Moro Moira , Fanin Renato , Damiani Daniela , Tiribelli Mario 

TITLE=Novel e4a2 BCR∷ABL1 transcript with insertion of CSE1L exons 9 and 10 in a CML patient: a case report

JOURNAL=Frontiers in Oncology

VOLUME=Volume 15 - 2025

YEAR=2025

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2025.1596256

DOI=10.3389/fonc.2025.1596256

ISSN=2234-943X

ABSTRACT=The BCR::ABL1 fusion gene, resulting from the Philadelphia (Ph) chromosome, is the defining feature of Chronic Myeloid Leukemia (CML). The fusion transcript typically results from the juxtaposition of ABL1 exons 2 or 3 and BCR exons 1, 13, 14 or 19, while exons 6 and 8 are less frequently involved. Here, we report the first case of a translocation in a patient with newly diagnosed chronic-phase CML harboring a novel e4a2 BCR::ABL1 fusion gene. This unique fusion includes a 298 bp insertion, derived from a CSE1L gene exons 9 and 10, at the fusion site. The patient showed resistance to first-line dasatinib but achieved a molecular response with the third-generation tyrosine kinase inhibitor ponatinib.