Current and evolving understanding of atypical chronic myeloid leukemia

Atypical chronic myeloid leukemia (aCML) is a BCR-ABL1 negative myelodysplastic (MDS)/myeloproliferative (MPN) neoplasm with poor overall survival. The current 2016 WHO classification of myeloid neoplasms allows clinicians to more accurately differentiate aCML from its similar MDS/MPN overlap and MPN counterparts. In addition, the advent of next-generation sequencing has expanded our understanding of the molecular pathogenesis of aCML and its therapeutic potential. Hematopoietic stem cell transplant (HSCT) remains the first consideration in the treatment algorithm for aCML, however, with the advances in mutational analysis, opportunities for targeted therapy have expanded. In this review, we highlight the current classification, diagnostic criteria, and molecular pathogenesis of aCML. We also discuss the therapeutic implications of the heterogeneous molecular fingerprint of aCML focusing on emerging targeted therapies, specifically ruxolitinib, dasatinib, and trametinib. Future disease management will rely on clinical trial development focused on new mutational drug targets, combination therapies, and signaling pathway dysregulation.