A Study of Mezigdomide in Healthy Participants and Participants With Hepatic Impairment

Inclusion Criteria: Hepatic Impaired Participants: * Participants have mild, moderate, or severe hepatic impairment or cirrhosis due to chronic hepatic disease and/or prior alcohol use. * Participants have mild (Group A), moderate (Group B), or severe (Group C) hepatic impairment as defined by Child-Pugh Score. Matched Healthy Participants: * Participant must be free of any clinically significant disease that would interfere with the study evaluations. * Participant must have liver-related laboratory test results within the respective reference ranges or with clinically insignificant excursions therefrom as agreed by the investigator. Exclusion Criteria: All Participants: * History of chronic pruritus or dermatologic syndromes that may be confounded with reactions to mezigdomide. * Contraindication or intolerance to first-generation antihistamine medications. Hepatic Impaired Participants: -Clinical laboratory test results: * Platelet count lower than 30,000/microliter (μL) at screening or Day -1. * Absolute neutrophil counts lower than 1,500/μL at screening or Day -1. Matched Healthy Participants: -History of or suspected benign ethnic neutropenia. Other protocol-defined inclusion/exclusion criteria apply