MOS101

MOS101 is a potent and selective small molecule inhibitor of Ubiquitin Specific Peptidase 7 (USP7), currently being developed by Mosaic Therapeutics. USP7 is a deubiquitinating enzyme that plays a critical role in regulating the stability of key oncogenic and tumor-suppressive proteins, most notably the MDM2-p53 axis. By inhibiting USP7, MOS101 promotes the degradation of MDM2, which in turn leads to the stabilization and reactivation of the p53 tumor suppressor protein, triggering cell cycle arrest and apoptosis in p53-wildtype cancer cells. Mosaic Therapeutics, a spin-out from the Wellcome Sanger Institute and the Netherlands Cancer Institute, is positioning MOS101 for the treatment of biomarker-selected solid tumors. The compound is being evaluated both as a monotherapy and in combination with other targeted agents, such as the MDM2 inhibitor ASTX295 and PARP inhibitors like olaparib, to overcome resistance and enhance therapeutic efficacy in genetically defined patient populations.