WAY-331603 is primarily used in scientific research to study the role of the GPR139 receptor, a G-protein-coupled receptor expressed in the brain. It acts as a potent and selective antagonist of GPR139, making it a valuable tool for investigating the receptor’s involvement in neurological processes. Researchers use WAY-331603 to explore potential links between GPR139 and conditions such as depression, schizophrenia, and Parkinson’s disease. Due to its selectivity, it helps clarify signaling pathways and behavioral outcomes in preclinical models without significant off-target effects. It is not used clinically and remains restricted to laboratory and pharmacological research settings.