A Phase I, Open-Label, Mass Balance Study of [14C]-Iberdomide in Healthy Subjects.

Background: Iberdomide is a novel potent cereblon modulator (CELMoD^®) agent, which is currently under clinical development for hematological malignancies. A human mass balance study was conducted to characterize the biotransformation and excretion pathways of iberdomide.

Method: After a single dose of radiolabelled [¹⁴C]-iberdomide (1 mg) in six healthy subjects. Blood, urine, and fecal samples were collected for pharmacokinetics, mass balance, and clinical laboratory assessments.

Results: Results showed that a single oral dose of 1 mg iberdomide was generally well tolerated in healthy subjects. The recovery of [¹⁴C]-iberdomide-derived radioactivity in humans was 45.9% in urine and 42.6% in feces. Based on exposure (area under the concentration-time curve [AUC_0-24]), iberdomide and M12 (metabolites) accounted for approximately 59% and 14% of circulating total radioactivity (TRA) exposure, respectively. Of the 88.5% TRA excreted, approximately 27% was excreted as unchanged iberdomide and 62% as metabolites, with similar amounts of excreted metabolites in the urine (16%) and feces (11%).

Conclusion: Biotransformation of iberdomide in humans included multiple oxidations of the morpholino moiety as well as glutarimide ring hydrolysis of parent and oxidized metabolites and a combination of these pathways. Iberdomide was the predominant component in human plasma, with metabolite M12 being the most prominent circulating metabolite. In excreta, similar iberdomide-derived radioactivity was found in urine and feces.

Trial registration number: NCT03294603.