Pediatric Acute Myeloid Leukemia (AML): NOTCH1 activation influencing prognosis through Transforming Growth Factor-B (TGF-Beta) / SETBP1; Report of a Pilot Study from Saudi Arabia

Objective: NOTCH1 is now established to play a key role in the prognosis of several hematological malignancies. Notch proteins are multifaceted and involved in several key cellular functions with extensive crosstalk with other critical pathways; therefore, it is important to investigate NOTCH1 expression and its influence on other oncogenic pathways molecules in AML. In this pilot study, we correlated NOTCH1 and associated pathway expression patterns among childhood AML patients and correlated it with hematological parameters and overall survival (OS) data. Methodology: RNA from diagnostic BM biopsies (n=35) were subjected to expression analysis employing nCounter Pan-Cancer pathway panel by Nanostring technologies. Laboratory and clinical data were correlated with expression of NOTCH1 and several other oncogenic signaling pathways (n=780). nSolver software v3 and SPSS software v24.0 were utilized for statistical evaluation. Hierarchical clustering and principle component analyses were performed employing Qlucore Omics Explorer v3.2. Results: 35 -AML patients (median age 8 yrs., range <1-18 yrs.) were dichotomized into low NOTCH1 (17/35; 49%) and high NOTCH1 (18/35; 51%) groups based on receiver operating characteristic (ROC) curve analysis (74% AUC; 82% sensitivity /68% specificity). Age, gender, hematological data or molecular risk factors (FLT3 mutation/molecular fusion) exposed no significant differences across these two distinct NOTCH1expression groups (P > 0 .05). High NOTCH1 expression was linked with high expression of NOTCH1 legend (Dll1) (P<0.001/fold >2.5). Our data also showed that high NOTCH1 mRNA is interrelated with heightened expression of positive regulator of the NOTCH signaling pathway (DTX1/DTX3). High NOTCH1 samples also showed high expression of TGRF-b associated protein SETBP1(P<0.001/fold >2.5) (Figure 1A). The level of NOTCH1 expression did not correlate with mortality {5/17 (29%) vs. 6/17; (35%) P > 0.05}. Low NOTCH1 expressers showed better OS {740 days vs. 579 days; log-rank P=< 0.007; HR 6.3 (1.36-29.26)} Conclusion: Our pilot study identified high Notch1 expression through canonical pathway as an important poor prognostic marker among pediatric AML patients which is independent of conventional prognostic markers and can provide insights into novel potential therapeutic target. Our study has identified that high expression of the molecules linked with NOTCH1 pathway are an important poor prognostic marker among childhood AML patients. NOTCH1 expression also shows cross talk with several other signal transduction pathways especially TGFb / SETBP1 which are also linked with poor prognosis.