YCH3124 (compound Z33) is a USP7 inhibitor ( IC 50 =41.9 nM) with antitumor activity. YCH3124 has good in vitro antiproliferative activity against various tumor cells including LNCaP ( IC 50 =3.6 nM) and CHP-212 ( IC 50 =9.9 nM). In addition, YCH3124 disrupts cell cycle progression by restricting G1 phase and induces apoptosis in CHP-212 cells.