Global gene expression of pediatric acute myeloid leukemia

Somatic mutations are rare in pediatric AML (pAML), indicating alternate strategies are needed to identify new, pediatric AML-specific, druggable targets. We defined the enhancer landscape of 22 pAML patient samples and observed many known leukemia regulators are SE-associated in pAML. We confirmed that the expression of several of these SE-associated genes correlated with gene expression by RNA-Seq. The retinoic acid receptor alpha (RARA) gene was differentially regulated in our cohort and present in all cyto/molecular subtypes tested, totaling 64% of the pAML samples. RARA SE-positive pAML cell lines and samples had higher RARA mRNA levels than RARA SE-negative samples and also were specifically sensitive to the synthetic RARA agonist tamibarotene in vitro, with halted proliferation and upregulated retinoid target genes. Tamibarotene prolonged survival and suppressed the leukemia burden of a RARA SE-positive pAML patient-derived xenograft (PDX) mouse model compared to a RARA SE-negative PDX. These data demonstrate the utility of leveraging chromatin regulation to identify new dependencies in pediatric AML and specifically lay the preclinical foundation for a tamibarotene trial in children with relapsed/refractory AML. Global bulk RNA-sequencing of pediatric acute myeloid leukemia samples