Are cathepsin k inhibitors just another class of anti-resorptives?

Several antiresorptive drugs are available for the treatment of osteoporosis, but all have limitations. From thisperspective, inhibitionofcathepsinKisanattractivenew target; it is the proteinase responsible for the digestion of bone matrix, and the effects of genetic deficiency in humans (pyknodysostosis) are restricted to the skeleton, where it causes failure of resorption. For these reasons, several cathepsin K inhibitors (CKIs) have been evaluated as possible therapeutics to prevent bone loss. They have been found to be potent and specific inhibitors of resorption. The first-inclass,odanacatib, isalready in the late stagesofphase3 trials. Although developed as antiresorptive agents, there is evidence that these agents also possess anabolic activity, the basis for which will be explored in this commentary.