Osamu Irie

Discovery of selective and nonpeptidic cathepsin S inhibitors

Nonpeptidic, selective, and potent cathepsin S inhibitors were derived from an in-house pyrrolopyrimidine cathepsin K inhibitor by modification of the P2 and P3 moieties. The pyrrolopyrimidine-based inhibitors show nanomolar inhibition of cathepsin S with over 100-fold selectivity against other cysteine proteases, including cathepsin K and L. Some of the inhibitors showed cellular activities in mouse splenocytes as well as oral bioavailabilities in rats.

Discovery of Orally Bioavailable Cathepsin S Inhibitors for the Reversal of Neuropathic Pain

Cathepsin S inhibitors are well-known to be an attractive target as immunological therapeutic agents. Recently, our gene expression analysis identified that cathepsin S inhibitors could also be effective for neuropathic pain. Herein, we describe the efficacy of selective cathepsin S inhibitors as antihyperalgesics in a model of neuropathic pain in rats after oral administration.

Overcoming hERG issues for brain-penetrating cathepsin S inhibitors: 2-cyanopyrimidines. Part 2.

We describe here orally active and brain-penetrant cathepsin S selective inhibitors, which are virtually devoid of hERG K(+) channel affinity, yet exhibit nanomolar potency against cathepsin S and over 100-fold selectivity to cathepsin L. The new non-peptidic inhibitors are based on a 2-cyanopyrimidine scaffold bearing a spiro[3.5]non-6-yl-methyl amine at the 4-position. The brain-penetrating cathepsin S inhibitors demonstrate potential clinical utility for the treatment of multiple sclerosis and neuropathic pain.

Effect of Cathepsin K Inhibitors on Bone Resorption

On the basis of the pyrrolopyrimidine core structure that was previously discovered, cathepsin K inhibitors having a spiro amine at the P3 have been explored to enhance the target, bone marrow, tissue distribution. Several spiro structures were identified with improved distribution toward bone marrow. The representative inhibitor 7 of this series revealed in vivo reduction in C-terminal telopeptide of type I collagen in rats and monkeys.

4-Amino-2-cyanopyrimidines: Novel scaffold for nonpeptidic cathepsin S inhibitors

We describe here a novel 4-amino-2-cyanopyrimidine scaffold for nonpeptidomimetic cathepsin S selective inhibitors. Some of the synthesized compounds have sub-nanomolar potency and high selectivity toward cathepsin S along with promising pharmacokinetic and physicochemical properties. The key structural features of the inhibitors consist of a combination of a spiro[2.5]oct-6-ylmethylamine P2 group at the 4-position, a small or polar P3 group at the 5-position and/or a polar group at the 6-position of the pyrimidine.

Structure-based design of substituted piperidines as a new class of highly efficacious oral direct Renin inhibitors.

A cis-configured 3,5-disubstituted piperidine direct renin inhibitor, (syn,rac)-1, was discovered as a high-throughput screening hit from a target-family tailored library. Optimization of both the prime and the nonprime site residues flanking the central piperidine transition-state surrogate resulted in analogues with improved potency and pharmacokinetic (PK) properties, culminating in the identification of the 4-hydroxy-3,5-substituted piperidine 31. This compound showed high in vitro potency toward human renin with excellent off-target selectivity, 60% oral bioavailability in rat, and dose-dependent blood pressure lowering effects in the double-transgenic rat model.

New chemotypes for cathepsin K inhibitors

Cyano pyrimidine acetylene and cyano pyrimidine t-amine, which belong to a new chemical class, were prepared and tested for inhibitory activities against cathepsin K and the highly homologous cathepsins L and S. The use of novel chemotypes in the development of cathepsin K inhibitors has been demonstrated by derivatives of compounds 1 and 8.