Identification of metabolites of evobrutinib in rat and human hepatocytes by using ultra-high performance liquid chromatography coupled with diode array detector and Q Exactive Orbitrap tandem mass spectrometry

Evobrutinib is a highly selective inhibitor of Bruton's tyrosine kinase (Btk) which may be clinically effective in treating certain autoimmune diseases. The purpose of the present study was to investigate the metabolism of evobrutinib in rat and human hepatocytes. Evobrutinib was incubated with rat and human hepatocytes at 37°C for 2 hours after which the samples were analyzed by ultra-high performance liquid chromatography with diode array detection and Q Exactive Orbitrap tandem mass spectrometry (UPLC-DAD-Q Exactive Orbitrap-MS). The acquired data were processed by MetWorks™ software using mass effect filter and background subtraction functions. Under these conditions, 23 metabolites were detected and their identities proposed. Among these metabolites, M13 and M15 were identified by comparison of their retention times, accurate masses, and fragment ions with those of authentic Reference Standards. The metabolic pathways of evobrutinib were proposed accordingly. Our results demonstrated that evobrutinib was metabolized via hydroxylation, hydrolysis, O-dealkylation, glucuronidation, and GSH conjugation. Species-related metabolic differences between rat and human hepatocytes were observed. M1-M4 were rat-specific metabolites. M13 (hydroxyl-evobrutinib) was the major metabolite whereas M15 (evobrutinib-diol) was a minor metabolite in rat hepatocytes. On the other hand, M6, M11, M16, M17, and M19 were human-specific metabolites. M15 was the most abundant metabolite whereas M13 was the minor metabolite in human hepatocytes. This study provides preliminary information regarding the metabolism of evobrutinib that may be helpful in understanding the pharmacology of evobrutinib.