An update on mixed phenotype acute leukemia

Abstract

Mixed phenotype acute leukemias (MPALs) are a heterogeneous group of acute leukemias that show differentiation along more than one lineage. MPAL are rare and account for <5 % of all acute leukemias and demonstrate an inferior prognosis compared with standard acute lymphoblastic or myeloid leukemias. Historically, due to the limited understanding of its underlying pathogenesis, there were no well-established classification schemes, leading to difficulty in both diagnosis and treatment. With the advent of new nomenclature and algorithms, including the European Group for the Immunological Characterization of Leukemias (EGIL) scoring system, World Health Organization (WHO) tumor classification, and International Consensus Classification (ICC), these entities are better defined and there have been significant changes in clinical management. Additionally, an increasing variety of molecular and cytogenetic abnormalities have been recognized, which have improved the diagnostic classifications and may represent important potential therapeutic targets. However, due to its rarity, current evidence and recommendations on the clinical approach to MPAL are largely based on retrospective studies with relatively small cohorts, and it remains a diagnostic and therapeutic dilemma. In this review, we discuss the most updated classifications, genomic complexity, and diagnostic and therapeutic strategies for MPAL.