Novel Indirect AMP-Activated Protein Kinase Activators: Identification of a Second-Generation Clinical Candidate with Improved Physicochemical Properties and Reduced hERG Inhibitory Activity

This study reports the synthesis and evaluation of novel indirect AMP-activated protein kinase (AMPK) activators. The series of compounds selectively inhibited cell growth in several human breast cancer cell lines by activating AMPK. We performed back-up medicinal chemistry synthetic research on ASP4132, a previously reported as a compound for clinical development that acts as an indirect AMPK activator. This led to the successful identification of 4-({4-[5-({1-[(5-ethoxypyrazin-2-yl)methyl]-4-fluoropiperidin-4-yl}methoxy)-3-methylpyridine-2-carbonyl]piperazin-1-yl}methyl)benzonitrile succinate (27b), a potent, highly aqueous soluble and metabolically stable compound in human hepatocytes. Compound 27b also showed weaker human Ether-a-go-go Related Gene (hERG) inhibitory activity than that of compound 13 and ASP4132. Therefore, 27b was a promising AMPK activator and a second-generation clinical candidate for treatment for human cancer.