ABL1 and acute lymphoblastic leukemia: Moreover, the results obtained from this study (n = 59) showed that deletions in IKZF1 in wild-type ABL-class fusion ALL patients presented more reliable prognostic properties than IKZF1 deletions with or without additional deletions in PAX5 or CDKN2A/B. This Ponte di Legno study proves that the outcome for children with ABL-class fusion is highly unfavorable without TKIs.