Background: Non-mutational aberrations of p53 function are a common event in AML. Using fragment-based drug discovery we have identified a Murine double minute 2 (MDM2) antagonist that potently activates p53 pathway. Here, we present the discovery of a novel patient selection strategy for MDM2 antagonist-induced apoptosis in wild-type p53 AML. Material and Methods: Cell panel screen and bioinformatics analyses of p53 wild-type AML cell lines that undergo apoptosis following Compound 1 (MDM2 antagonist) treatment versus those that do not were employed to identify novel patient selection strategy. Correlation between low levels of SKP2 (S-Phase Kinase Associated Protein 2) and induction of apoptosis following Compound 1 treatment was tested in vitro using Western Blot and flow cytometry analysis. Genetic manipulation of SKP2 levels using knockdown and over-expression approaches in wild-type p53 AML cells were used to validate the role of SKP2 expression in in vitro and in vivo experiments. Finally, bone marrow-derived primary AML blasts were tested to confirm the novel patient selection strategy. Results: Cell panel screen of p53 wild-type cell lines showed a wide range of sensitivity to Compound 1 suggesting that additional biomarkers are required to ensure patient stratification. Further bioinformatics analysis of apoptotic and non-apoptotic AML cancer cell lines following treatment with Compound 1 demonstrated differential gene expression levels and identified several potential predictive biomarkers. Western blot and flow cytometry analyses demonstrated that basal SKP2 expression level is lower in apoptotic AML cell lines than in non-apoptotic cells. Over-expression of SKP2 levels in MV4-11 cells reduced MDM2 antagonist-dependent cell death in previously apoptotic cell line. Similarly, SKP2 knockdown in OCI-AML3 cells increased MDM2 antagonist-induced cytotoxicity. Studies performed in mouse systemic AML model in vivo also demonstrated that high levels of SKP2 reduced p53 response to Compound 1. Finally, the correlation of SKP2 expression and Compound 1 sensitivity was confirmed in primary AML blasts isolated from patients. Conclusions: This work demonstrates in vitro and in vivo activity of MDM2 antagonist in AML models with low basal SKP2 levels. These pre-clinical data validate low levels of SKP2 as a novel patient selection strategy in AML and support the clinical investigation of MDM2 antagonist as therapeutic strategy for the treatment of SKP2low p53wt AML. No conflict of interest.