Development of a potent and selective cell penetrant Legumain inhibitor.

This Letter describes the continued SAR exploration of small molecule Legumain inhibitors with the aim of developing a potent and selective in vitro tool compound. Work continued in this Letter explores the use of alternative P2–P3 linker units and the P3 group SAR which led to the identification of 10t, a potent, selective and cellularly active Legumain inhibitor. We also demonstrate that 10t has activity in both cancer cell viability and colony formation assays.