Discovery of AMG 232, a Small Molecule Disrupting the p53-MDM2 Protein–Protein Interaction and Development of a Validation-Ready Process for Its Manufacture

Abstract

Activation of the tumor suppressor p53 is widely regarded as a promising axis for treating a range of human cancers. AMG 232 is a small molecule designed to disrupt the protein-protein interaction between p53 and its negative regulator, MDM2, leading to increased tumor suppressive activity. The discovery of AMG 232 stems from a de novo design effort that was closely informed by protein co-crystal structures of known inhibitors at the time. From a micromolar starting point, an iterative, structure-based design process was used to optimize both anticipated and unexpected contacts between the inhibitors and the MDM2 protein by exploiting conformational control. The result was a compound possessing picomolar binding affinity for MDM2 within a unique and stereochemically rich chemotype. A robust process to prepare AMG 232 was developed. Highlights of those development efforts include the following: (i) use of a new bench-stable Vilsmeier reagent, methoxymethylene-N,N-dimethyliminium methylsulfate, for selective in situ activation of a primary alcohol intermediate; (ii) use of a novel stable isopropyl calcium sulfinate reagent ensuring reliable manufacture of a sulfone intermediate; (iii) development of a safe ozonolysis process performed in an aqueous solvent mixture in either batch or continuous manufacturing mode; and (iv) control of the drug substance purity by crystallization.