Ph-like ALL is characterized by a diverse array of genetic alterations activating cytokine receptor and tyrosine kinase signaling.
Pediatric patients with Ph-like ALL can be identified in real time for effective treatment stratification.
Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a high-risk subtype characterized by genomic alterations that activate cytokine receptor and kinase signaling. We examined the frequency and spectrum of targetable genetic lesions in a retrospective cohort of 1389 consecutively diagnosed childhood B-ALL patients with high-risk clinical features and/or elevated minimal residual disease at the end of remission induction therapy. The Ph-like gene expression profile was identified in 341 of 1389 patients, 57 of which were excluded from additional analysis because of the presence of BCR-ABL1 (n=46) or ETV6-RUNX1 (n=11). Among the remaining 284 (20.4%) patients, overexpression and rearrangement of CRLF2 (IGH-CRLF2 or P2RY8-CRLF2) were identified in 124 (43.7%), with concomitant genomic alterations activating the JAK-STAT pathway (JAK1, JAK2, IL7R) identified in 63 patients (50.8% of CRLF2-rearranged cases). Of the remaining patients, using RT-PCR or transcriptome sequencing, we identified targetable ABL-class fusions (ABL1, ABL2, CSF1R and PDGFRB) in 14.1% of Ph-like ALL cases, EPOR rearrangements or JAK2 fusions (8.8%), alterations activating other JAK-STAT signaling genes (IL7R, SH2B3, JAK1; 6.3%) and other kinases (FLT3, NTRK3, LYN; 4.6%), and mutations involving the Ras pathway (KRAS, NRAS, NF1, PTPN11; 6%). We identified eight new rearrangement partners for four kinase genes previously reported to be rearranged in Ph-like ALL. The current findings provide support for the precision-medicine testing and treatment approach for Ph-like ALL that has been implemented in Children's Oncology Group ALL trials.
- Submitted December 27, 2016.
- Accepted April 9, 2017.
- Copyright © 2017 American Society of Hematology
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