Metabolism and excretion of [ 14 C]mobocertinib, a selective covalent inhibitor of EGFR exon 20 insertion mutants, in healthy male subjects.

Mobocertinib (formerly known as TAK-788) is a targeted covalent tyrosine kinase inhibitor of epidermal growth factor receptor with exon 20 insertion mutations. This article describes the metabolism and excretion of mobocertinib in healthy male subjects after a single oral administration of [ 14 C]mobocertinib. Mobocertinib related materials were highly covalently bound to plasma proteins such as human serum albumin. The mean extraction recovery of total radioactivity was only 3.9% for 6 individual Hamilton pooled plasma samples. After extraction, mobocertinib was the most abundant component accounting for 7.7% of total extracted circulating radioactivity (TECRA) in the supernatant. Each of identified metabolites accounted for <10% of TECRA. Mobocertinib underwent extensive first-pass metabolism with the fraction of the dose absorbed estimated to be approximately 91.7%. Fecal excretion of mobocertinib metabolites was the major elimination route. Mobocertinib was mainly eliminated via oxidative metabolism with a fraction of approximately 88% metabolized by CYP3A4/5. The other minor elimination pathways included cysteine conjugation, metabolism by other CYPs, and renal excretion of unchanged mobocertinib. Significance Statement This manuscript describes the metabolism and excretion of a targeted covalent inhibitor mobocertinib in humans after a single oral administration of [ 14 C]mobocertinib. Mobocertinib was highly covalently bound to human plasma proteins. No metabolite accounted for >10% of total extracted circulating radioactivity in human plasma. Mobocertinib was mainly eliminated via CYP3A4/5 mediated oxidative metabolism followed by fecal excretion after approximately 91.7% of the dose was absorbed.