2-(Fluoromethoxy)-4 '-(S-methanesulfonimidoyl)-1,1 '-biphenyl (UCM-1306), an Orally Bioavailable Positive Allosteric Modulator of the Human Dopamine D-1 Receptor for Parkinson's Disease

Tolerance development caused by dopamine replacement with L-DOPA and therapeutic drawbacks upon activation of dopaminergic receptors with orthosteric agonists reveal a significant unmet need for safe and effective treatment of Parkinson's disease. In search for selective modulators of the D-1 receptor, the screening of a chemical library and subsequent medicinal chemistry program around an identified hit resulted in new synthetic compound 26 [UCM-1306, 2-(fluoromethoxy)-4'-(S-methanesulfonimidoyl)-1,1'-biphenyl] that increases the dopamine maximal effect in a dose-dependent manner in human and mouse D-1 receptors, is inactive in the absence of dopamine, modulates dopamine affinity for the receptor, exhibits subtype selectivity, and displays low binding competition with orthosteric ligands. The new allosteric modulator potentiates cocaine-induced locomotion and enhances L-DOPA recovery of decreased locomotor activity in reserpinized mice after oral administration. The behavior of compound 26 supports the interest of a positive allosteric modulator of the D-1 receptor as a promising therapeutic approach for Parkinson's disease.