The Acquisition of Molecular Drivers in Pediatric Therapy-Related Myeloid Neoplasms

Pediatric therapy-related myeloid neoplasms (tMN) occur in children after exposure to cytotoxic therapy and have a dismal prognosis1-4. The somatic and germline genomic alterations that drive these myeloid neoplasms in children and how they arise have yet to be comprehensively described. We use whole exome, whole genome, and/or RNA sequencing to characterize the genomic profile of 85 pediatric tMN cases (tMDS: n=29, tAML: n=56). Our data show that Ras/MAPK pathway mutations, alterations in RUNX1 or TP53, and KMT2A rearrangements are frequent somatic drivers, and we identify cases with aberrant MECOM expression secondary to enhancer hijacking. Unlike adults with tMN5-7, we find no evidence of pre-existing minor tMN clones (including those with TP53 mutations), but rather the majority of cases were unrelated clones arising as a consequence of cytotoxic therapy. These studies also uncover rare cases of lineage switch disease rather than true secondary neoplasms.EGA study EGAS00001004850