KT-253, A Novel MDM2 Degrader and p53 Stabilizer, Has Superior Potency and Efficacy Than MDM2 Small Molecule Inhibitors

KT-253 is a potent and selective heterobifunctional MDM2 degrader with superior activity to MDM2/p53 small molecule inhibitors. RS4;11 cells treated with KT-253 indicated no off-target protein degradation. All significantly upregulated proteins are p53 and its target genes. KT-253 overcomes p53/MDM2 feedback loop. Targeted proteomics analysis of MDM2 levels in RS4;11 cells shows that KT-253 (150 nM KT-253 for 15 minutes) can achieve greater than 90% degradation of MDM2 within 1 hour posttreatment, whereas MDM2 levels continued to increase 1 hour after treatment with DS-3032 A single dose of KT-253 drives sustained tumor regression in ALL xenografts. Targeted proteomic analysis of tumors demonstrates robust degradation of MDM2 1-hour post dosing with KT-253. This is associated with activation of the p53 pathway as evidenced by a corresponding upregulation of proteomics biomarkers p53, p21, and PHLDA3.