2,6-Difluorobenzamide derivatives as store-operated calcium channel (SOC) inhibitors

The Ca²⁺ entry from store-operated Ca²⁺ channel (SOC) is involved in regulating colorectal cancer progression, such as cell migration. SOC activation is due to STIM1 translocation and interaction with Orai1 upon Ca²⁺ depletion in the ER. Numerous SOC inhibitors, like 2-APB, have been developed and demonstrated their inhibition effects in the preclinical stage. However, most currently used SOC inhibitors have higher cytotoxicity or opposite effects at different doses, and the drugs to target SOC in the clinic are lacking. In this study, a total of 13 difluorobenzamide compounds had been synthesized and examined the inhibitory effects on SOC with Ca²⁺ imaging and wound-healing migration assay. Among them, 2,6-Difluoro-N-(5-(4-fluorophenyl)pyridine-2-yl)benzamide (MPT0M004, 8a) demonstrated a prominent inhibitory ability on SOC. Furthermore, the cell proliferation assay results showed that MPT0M004 (8a) had lower cytotoxicity than 2-APB, the reference compound. In the pharmacokinetic study, MPT0M004 (8a) has a long half-life (T_1/2 = 24 h) and lower daily dose administered intravenously with an oral bioavailability (F = 34%). Therefore, MPT0M004 (8a) has the potential to be a lead compound as a SOC inhibitor and further develop into a potential drug to treat colorectal cancer.