In 2009, large-scale gene expression profiling identified a high-risk B-cell precursor ALL (B-ALL) subtype, termed Philadelphia chromosome-like ALL (Ph-like ALL), which displays a gene expression profile similar to that of Philadelphia chromosome-positive ALL (Ph+ ALL), harbors a high frequency of IKZF1 (IKAROS family zinc finger 1) alterations, but lacks the hallmark BCR::ABL1 (breakpoint cluster region protein/Abelson 1) fusion gene of Ph+ ALL (Mullighan et al., 2009b; Den Boer et al., 2009). This evidence concerns the gene ABL1 and acute lymphoblastic leukemia.