SIM0501

SIM0501 is an oral, non-covalent, and highly selective small-molecule inhibitor of Ubiquitin Specific Peptidase 1 (USP1). USP1 is overexpressed in various tumors and plays a critical role in DNA damage response and repair. Inhibition of USP1 by SIM0501 promotes apoptosis in tumor cells, particularly those with homologous recombination deficiency (HRD), by disrupting DNA repair mechanisms. This mechanism leverages the concept of synthetic lethality, similar to but distinct from PARP inhibitors, offering potential benefits for patients with solid tumors—especially those resistant to PARP inhibitors. Preclinical studies have shown significant anti-proliferative activity against HRD tumors both as monotherapy and in combination with PARP inhibitors such as olaparib. SIM0501 was independently developed by Simcere Zaiming (a subsidiary of Simcere Pharmaceutical Group) and has received Investigational New Drug (IND) approval from both the US FDA and China’s NMPA for clinical trials targeting advanced solid tumors[1][2][7].