molecules of the month

Context. RLX-33 (Research Triangle Institute) is a nonpeptide relaxin-3/RXFP3 system antagonist. Evidence over the last 2 decades, since the discovery of relaxin‐3 in 2001, suggests that the protein, through its receptor RXFP3, regulates responses to stress, anxiety-related and motivated behaviors, circadian rhythms, learning and memory, and alcohol-seeking behavior, making the relaxin-3/RXFP3 system a desirable target for neuropsychiatric agents. Relaxin-3/RXFP3 system inhibitors described in the literature have all been peptide ligands, making RLX-33 the first nonpeptide antagonist to be reported. The small molecule has a key advantage over its peptide competitors in being more metabolically stable and amenable to oral administration. The preclinical properties of RLX-33 make it a promising lead from which a clinical candidate may emerge. Target. Relaxin‐3 is…