Bicyclic chiral scaffolds are privileged motifs in medicinal chemistry. Over the years, we have reported covalent bicyclic prolyl oligopeptidase inhibitors that were highly selective for POP over a number of homologous proteins. Herein, we wish to report the structure-based design and synthesis of a novel class of POP inhibitors based on hexahydroisoindoles. A docking study guided the selection of structures for synthesis. The stereochemistry, decoration, and position within the molecule of the bicyclic scaffolds were assessed virtually. Following the synthesis of the best candidates, in vitro assays revealed that one member of this chemical series was more active than any of our previous inhibitors with a Ki of 1.0 nM. Additional assays also showed that the scaffold of this potent inhibitor, in contrast to one of our previously reported chemical series, is highly metabolically stable, despite the foreseen potential sites of metabolism. Interestingly, computer docking calculations accurately predicted the optimal features of the inhibitors.

Abstract:In the early 2000s, the anticancer drug imatinib (Glivec ® ) appeared on the market, exhibiting a new mode of action by selective kinase inhibition. Consequently, kinases became a validated therapeutic target, paving the way for further developments. Although these kinases have been thoroughly studied, none of the compounds commercialized since then target cyclin-dependent kinases (CDKs). Following a recent and detailed review on the subject by Galons et al., we concentrate our attention on an updated list of compounds under clinical evaluation (phase I/II/III) and discuss their mode of action as ATP-competitive inhibitors. CDK inhibition profiles and clinical development stages are reported for the 14 compounds under clinical evaluation. Also, tentative progress for forthcoming potential ATP non-competitive inhibitors and allosteric inhibitors are briefly described, along with their limitations.