Sapitinib: reactive intermediates and bioactivation pathways characterized by LC-MS/MS.

Area of Science:

• Pharmacology
• Medicinal Chemistry
• Drug Metabolism

Background:

• Sapitinib (SAP) is a potent epidermal growth factor receptor (EGFR) family inhibitor.
• SAP demonstrates superior inhibition of EGF-driven proliferation compared to gefitinib in tumor cell lines.

Purpose of the Study:

• To investigate the in vitro metabolic pathways of Sapitinib (SAP).
• To identify and characterize reactive intermediates generated during SAP metabolism.
• To elucidate potential SAP bioactivation pathways.

Main Methods:

• In vitro incubation of SAP with human liver microsomes.
• Trapping of reactive intermediates using potassium cyanide (for iminium) and methoxyamine (for aldehyde).
• Structural characterization of metabolites and intermediates using liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Main Results:

• Hydroxylation at the piperidine moiety was identified as the major in vitro metabolic pathway.
• Six phase I metabolites and three reactive intermediates (two iminium, one aldehyde) were characterized.
• Two probable SAP bioactivation pathways involving piperidine ring nitrogen and N-acetamide group were proposed.

Conclusions:

• Sapitinib metabolism involves hydroxylation and oxidative dealkylation, leading to reactive intermediates.
• The study presents the first structural characterization of Sapitinib reactive intermediates.
• Understanding these pathways is crucial for assessing SAP's in vivo safety and efficacy.