Discovery of novel 1,2,3,4-tetrahydrobenzo[4, 5]thieno[2, 3-c]pyridine derivatives as potent and selective CYP17 inhibitors

The inhibition of CYP17 to block androgen biosynthesis is a well validated strategy for the treatment of prostate Cancer. Herein we reported the design, synthesis and structure-activity relationship (SAR) study for a series of novel 1,2,3,4- tetrahydrobenzo[4,5]thieno[2,3-c]pyridine derivatives. Some analogs demonstrated a potent inhibition to both rat and human CYP17 protein and reduced testosterone production in human H295R cell line. Some analogs also showed high selectivity against other CYP Enzymes such as 3A4, 1A2, 2C9, 2C19 and 2D6, which may limit side effects due to drug-drug interactions. Among these analogs, the most potent compound 9c showed 1.5 fold more potent against rat and human CYP17 protein than that of abiraterone (IC₅₀ = 16 nM and 20 nM vs. 25 nM and 36 nM respectively). In NCI-H295R cells, the inhibitory effect of compound 9c on testosterone production (52± 2%) was also more potent than that of abiraterone (74± 15%) at the concentration of 1 μM. Further, it was shown that 9c reduced plasma testosterone level in a dose-dependent manner in Sprague-Dawley rats. Thus, analog 9c maybe a potential agent used for the treatment of prostate Cancer.