<i>BCR-ABL1</i>-like B-Acute Lymphoblastic Leukemia/Lymphoma: A Comprehensive Review.

Abstract

In the 2016 update of the World Health Organization (WHO) classification of hematopoietic neoplasms, <i>BCR-ABL1</i>-like B-acute lymphoblastic leukemia/lymphoma (B-ALL) is added as a new provisional entity that lacks the <i>BCR-ABL1</i> translocation but shows a pattern of gene expression very similar to that seen in B-ALL with <i>BCR-ABL1</i>. To review the kinase-activating alterations and the diagnostic approach for <i>BCR-ABL1</i>-like B-ALL. We provide a comprehensive review of <i>BCR-ABL1</i>-like B-ALL based on recent literature and the 2016 update of the World Health Organization classification of hematopoietic neoplasms. Several types of kinase-activating alterations (fusions or mutations) are identified in <i>BCR-ABL1-</i>like B-ALL. The main categories are alterations in the ABL class family of genes, encompassing <i>ABL1, ABL2, PDGFRB, PDGFRA</i> (rare), and colony-stimulating factor 1 receptor (<i>CSF1R</i>) fusions, or the JAK2 class family of genes, encompassing alterations in <i>JAK2, CRLF2, EPOR</i>, and other genes in this pathway. These alterations determine the sensitivity to tyrosine kinase inhibitors. As a wide variety of genomic alterations are included in this category, the diagnosis of <i>BCR-ABL1</i>-like B-ALL is extremely complex. Stepwise algorithms and comprehensive unbiased testing are the 2 ways to approach the diagnosis of <i>BCR-ABL1</i>-like B-ALL.