Ph-like acute lymphoblastic leukemia.

Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a newly identified high-risk (HR) B-lineage ALL subtype, accounting for ∼15% of children with National Cancer Institute-defined HR B-ALL. It occurs more frequently in adolescents and adults, having been reported in as much as 27% of young adults with ALL between 21 and 39 years of age. It exhibits adverse clinical features, confers a poor prognosis, and harbors a diverse range of genetic alterations that activate cytokine receptor genes and kinase signaling pathways, making it amenable to treatment with tyrosine kinase inhibitor (TKI) therapy. Multiple groups are currently conducting clinical trials to prospectively screen patients with Ph-like ALL and incorporate the relevant TKI for those harboring ABL-class gene rearrangements or those with JAK-STAT pathway alterations. The success of combinatorial treatment of TKI with chemotherapy in the setting of Ph-positive ALL suggests that this approach may similarly improve outcomes for patients with Ph-like ALL. Hence, Ph-like ALL illustrates the modern treatment paradigm of precision medicine and presents unique opportunities for harnessing international collaborations to further improve outcomes for patients with ALL.