On August 22, 2024, Simcere Zaiming, an innovative oncology company and a subsidiary of Simcere Pharmaceutical Group (2096.HK), announced that SIM0508, a DNA polymerase θ (Pol θ) small molecule inhibitor developed independently by the company, has received Clinical Trial Approval from the National Medical Products Administration of China. This approval allows for the commencement of clinical trials to evaluate the efficacy of SIM0508 in treating locally advanced/metastatic solid tumor.
Homologous recombination is a vital cellular process for repairing DNA double-strand breaks. When homologous recombination deficiency (HRD) occurs, genomic instability can lead to tumor development. HRD tumors rely on an alternative repair pathway called microhomology-mediated end joining (MMEJ), where Pol θ plays a crucial role. Interestingly, Pol θ is rarely expressed in normal tissues but highly expressed in various malignant tumor cells. By blocking Pol θ, we can disrupt the MMEJ pathway, precisely targeting HRD tumor cells while sparing normal cells.
SIM0508, a potent small molecule inhibitor, selectively targets and inhibits Pol θ, effectively blocking MMEJ repair and precisely inhibiting the proliferation of HRD tumor cells. SIM0508 also has potential synergy when used in combination with poly (ADP-ribose) polymerase (PARP) inhibitors or chemotherapeutic agents. Preclinical studies of SIM0508 revealed favorable oral pharmacokinetics and safety, with no evident hematologic toxicities. These findings suggest that combining SIM0508 with PARP inhibitors or chemotherapeutic agents carries a low risk of additive toxicity. The preclinical data were presented at the 2024 American Association for Cancer Research (AACR) Annual Meeting.
Simcere Zaiming’s pipeline currently includes 13 innovative drug projects either in the clinical study stage or with clinical approval.