JL Luhmann, J Kater, L Wendeburg, A Moricke, G Cario, M Schrappe, B Schlegelberger, M Stanulla, D Steinemann.
Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer. Leukemic cells are characterized by structural and numeric genomic aberrations, which strongly correlate with prognosis and clinical outcome. A proportion of ALLs cannot be assigned to a distinct subgroup and are classified as B-other. Within this group the IKZF1plus-profile was described as a copy-number based and MRD-dependent stratification profile with very poor prognosis. It is unknown so far, if this profile presents as a surrogate for other unidentified underlying variants. Using optical genome mapping (OGM), a method to detect all types structural variants, we retrospectively investigated IKZF1del/plus-ALL samples and searched for genomic aberrations driving or contributing to the poor prognosis for these patients. Applying OGM we detected several recurrent stratification markers associated with poor prognosis such as a ETV6::ABL1 fusion (ins(12;9)), a PAX5::JAK2 fusion (inv(9)), a EBF1:PDGFRB fusion (t(5;5)). Additionally, we identified a novel NPAT::JAK2 fusion resulting from a t(9;11). Our preliminary data show that IKZF1del/plus-ALL carry additional markers that might be the drivers of the disease.