DRD1 and Parkinson disease: However,the development of allosteric modulators for GPCRs has been challengingand has afforded few FDA-approved drugs: the calcium-sensing receptorPAMs cinacalcet and etelcalcetide, the CCR5 receptor NAM maraviroc,the CXCR4 NAM/CXCR7 allosteric agonist plerixafor, the smoothenedreceptor NAM vismodegib, and the GABAA receptor PAM brexanolone.31−36 In this context, the positive allosteric modulation approach toupregulate D1R activity has been recently proposed as anovel strategy toward improved dopaminergic therapies for PD.