Phosphoproteomic profiling of pediatric B-ALL patients with MLL rearrangements

10001 Background: While the outcome for children with Acute Lymphoblastic Leukemia (ALL) has improved under current therapies, 30% do not have a favourable outcome. Infants with MLL rearrangements form the most striking example of ALL patients who have not benefited from the improved treatment regimens developed over recent decades. Our study aims to better map the biology of the MLL disease and to identify aberrantly activated phosphoproteins specific for MLL rearranged patients using phosphoproteomic measurement of signal transduction pathways (STPs). This will offer possibilities to identify new drug targets for more effective and less toxic targeted therapies. Methods: Reverse Phase Protein Arrays (RPPA) were employed to profile the working state of cellular STPs in 120 pediatric B-ALL specimens collected prior to treatment. The phosphorylation status of 92 key signalling proteins was analyzed. We compared 9 MLL rearranged patients vs 42 patients without known genomic aberrancies to find differentiall...