In vitro pharmacological profile of KW-6356, a novel adenosine A2A receptor antagonist/inverse agonist

by Selleckchem | Apr 06 2023

KW-6356 is a novel adenosine A2A receptor (A2A receptor) antagonist/inverse agonist, and its efficacy as monotherapy in Parkinson's disease (PD) patients has been reported. Istradefylline is a first-generation A2A receptor antagonist approved for use as adjunct treatment to levodopa/decarboxylase inhibitor in adult PD patients experiencing OFF episodes. In this study, we investigated the in vitro pharmacological profile of KW-6356 as an A2A receptor antagonist/inverse agonist and the mode of antagonism and compared them with istradefylline. In addition, we determined co-crystal structures of A2A receptor in complex with KW-6356 and istradefylline to explore the structural basis of the antagonistic properties of KW-6356. Pharmacological studies have shown that KW-6356 is a potent and selective ligand for the A2A receptor (the -log of inhibition constant = 9.93 {plus minus} 0.01 for human receptor) with a very low dissociation rate from the receptor (the dissociation kinetic rate constant = 0.016 {plus minus} 0.006 min-1 for human receptor). In particular, in vitro functional studies indicated that KW-6356 exhibits insurmountable antagonism and inverse agonism, while istradefylline exhibits surmountable antagonism. Crystallography of KW-6356- and istradefylline-bound A2A receptor have indicated that interactions with His2506.52 and Trp2466.48 are essential for the inverse agonism, while the interactions at both deep inside the orthosteric pocket and the pocket lid stabilizing the extracellular loop conformation may contribute to the insurmountable antagonism of KW-6356. These profiles may reflect important difference in vivo and help predict better clinical performance.

Significance Statement KW-6356 is a potent and selective adenosine A2A receptor antagonist/inverse agonist and exhibits insurmountable antagonism, while istradefylline, a first-generation adenosine A2A receptor antagonist, exhibits surmountable antagonism. Structural studies of adenosine A2A receptor in complex with KW-6356 and istradefylline explain the characteristic differences in the pharmacological properties of KW-6356 and istradefylline.

Comments：

The study investigated the in vitro pharmacological profile of KW-6356, a novel adenosine A2A receptor antagonist/inverse agonist, and compared it with istradefylline, a first-generation A2A receptor antagonist approved for use as adjunct treatment to levodopa/decarboxylase inhibitor in adult PD patients experiencing OFF episodes. The pharmacological studies showed that KW-6356 is a potent and selective ligand for the A2A receptor with a very low dissociation rate from the receptor. In vitro functional studies indicated that KW-6356 exhibits insurmountable antagonism and inverse agonism, while istradefylline exhibits surmountable antagonism. Crystallography of KW-6356- and istradefylline-bound A2A receptor indicated that interactions with His2506.52 and Trp2466.48 are essential for the inverse agonism of KW-6356, while the interactions at both deep inside the orthosteric pocket and the pocket lid stabilizing the extracellular loop conformation may contribute to the insurmountable antagonism of KW-6356. These profiles may reflect important differences in vivo and help predict better clinical performance.