A novel and potent VLA-4 antagonist based on trans-4-substituted cyclohexanecarboxylic acid

During the course of our study, it was revealed that the poor pharmacokinetic properties of a series of benzoic acid derivatives such as 1 should be attributed to the diphenylurea moiety. Thus, we replaced the diphenylurea moiety in 1 with a 2-( 2- methylphenylamino) benzoxazole moiety which mimics the diphenylurea structure. However, this modi. cation resulted in a significant decrease ( 3, IC(50) = 19 nM) in VLA-4 inhibitory activity compared to 1 ( IC(50) = 1.6 nM). To address this discrepancy, we worked on optimization of the carboxylic acid moiety in compound 3. As a result, our efforts have led to the discovery of trans-4-substituted cyclohexanecarboxylic acid derivative 11b (IC(50) = 2.8 nM) as a novel and potent VLA-4 antagonist. In addition, compound 11b exhibited favorable pharmacokinetic properties ( CL = 3.3ml/min/ kg, F = 51%) in rats. (c) 2008 Elsevier Ltd. All rights reserved.