ADORA2A and Parkinson disease: 8 of 11 FDA-approved drugs targeting A2AR are antagonists, along with compounds undergoing clinical trials (Fig. 1B).10 They are used to treat different diseases, mostly symptoms of neurodegenerative diseases like Parkinson's,11,12 as well as cancer.13,14 Although these molecules are chemically diverse (Fig. S1†), they all (i) lack the sugar moiety and (ii) feature a mono-, bi-, or tricyclic structure, which mimics the adenine part of adenosine.