CRLF2 gene expression, underlying genomic alterations, and their association with treatment outcome. (A) Expression of CRLF2 in 555 patients with precursor B-cell ALL (left) is shown relative to the median expression of all samples. The dashed line indicates the cutoff between a CRLF2 high- and CRLF2 low-expression group. (Right) Zoom on the 70 cases with greatest CRLF2 expression analyzed for underlying genomic CRLF2 aberrations. Cases with P2RY8-CRLF2 or IGH-CRLF2 rearrangement (red), additional copies of the CRLF2 gene locus (yellow), negative for the P2RY8-CRLF2 rearrangement but without FISH analysis (blue), and without CRLF2 aberrations (green) are shown. (B) Kaplan-Meier estimate of EFS (left) and CRI (right) at 6 years according to CRLF2 expression in all patients analyzed. (C) Kaplan-Meier estimate of EFS (left) and CRI (right) at 6 years according to CRLF2 expression and detected underlying genomic CRLF2 aberrations in all patients analyzed. For EFS, the P value comparing the CRLF2 high-/P2RY8 fusion-positive and the CRLF2 low-expression group is shown. (D) Kaplan-Meier estimate of EFS (left) and CRI (right) at 6 years according to CRLF2 expression in non-HR patients only. (E) Kaplan-Meier estimate of EFS (left) and CRI (right) at 6 years according to CRLF2 expression and detected underlying genomic CRLF2 aberrations in non-HR patients only. For EFS, the P value comparing the CRLF2 high/P2RY8 fusion-positive and the CRLF2 low-expression group is shown.