Development of potent and selective Cathepsin C inhibitors free of aortic binding liability by application of a conformational restriction strategy.

Cathepsin C plays a key role in the activation of several degradative enzymes linked to tissue destruction in chronic inflammatory and autoimmune diseases. Therefore, Cathepsin C inhibitors could potentially be effective therapeutics for the treatment of diseases such as chronic obstructive pulmonary disease (COPD) or acute respiratory distress syndrome (ARDS). In our efforts towards the development of a novel series of Cathepsin C inhibitors, we started working around AZD5248 (1), an α-amino acid based scaffold having potential liability of aortic binding. A novel series of amidoacetonitrile based Cathepsin C inhibitors were developed by the application of a conformational restriction strategy on 1. In particular, this work led to the development of a potent and selective Cathepsin C inhibitor 3p, free of aortic binding liability.