MC4R and obesity due to melanocortin 4 receptor deficiency: These interesting findingsemphasize that development of β-arrestin-biased MC4R ligandsmay represent an effective strategy for treating weight loss and obesity-relatedcardiometabolic diseases.4 Accordingly,MC4R ligands developed in this study could provide a new platformfor the development of functionally selective and safer β-arrestin-biasedMC4R agonists for weight loss and metabolic diseases in the futureand may cover the substantial and unmet requirements for therapeuticsfor obesity-related metabolic disorders.