USP7 and plasma cell myeloma: However, no specific USP47 inhibitors have currently been developed, although first-generation USP7 inhibitors, such as P5091 (1-[5-(2,3-dichloro phenylsulfanyl)−4-nitro-2thien l]ethanone) have been shown to inhibit both USP7 and USP47 with an IC50 of 4.2 μM and 4.3 μM, respectively, and antitumor efficacy in both in vitro and in vivo multiple myeloma xenograft models12,13.