Genomic and transcriptional landscape of P2RY8-CRLF2-positive childhood acute lymphoblastic leukemia

The mutational and transcriptional landscape of P2RY8-CRLF2-positive ALL was defined in 41 major clone fusion-positive cases including 19 matched diagnosis and relapse pairs by an integrated analysis of whole-exome and RNA sequencing. We detected a variety of frequently subclonal and highly unstable JAK/STAT but also RTK/Ras pathway activating mutations in 76% of cases at diagnosis and virtually all relapses. Unlike P2RAY8-CRLF2 that was lost in 32% of relapses, all other genomic deletions affecting lymphoid development and cell cycle remained stable. Only IKZF1 alterations predominated in relapsing cases and increased from initially 36 to 58% in matched cases. IKZF1¹s transcriptional signature revealed compromised stem cell features with signs of impaired lymphoid differentiation, enhanced focal adhesion, activated hypoxia pathway, deregulated cell cycle and increased drug resistance.EGA study EGAS00001001847