In-vitro metabolite identification for MEDI7219, an oral GLP-1 analog, using LC-MS/MS with CID and EAD approaches

Oral peptide therapeutics typically have short half-lives due to rapid degradation by digestive enzymes. Systematic peptide engineering and formulation optimization led to the development of a clinical candidate MEDI7219, an orally bioavailable glucagon-like peptide 1 (GLP-1) peptide, with greater stability than wild-type GLP-1 or semaglutide:~60% of MEDI7219 remained intact after 2 h in vitro incubation with simulated intestinal fluid. This study further investigates proteolytic stability by elucidating biotransformation products of MEDI7219 using liquid chromatography-mass spectrometry (LC-MS) methods. Peptide metabolism was assessed using in vitro pancreatin assay followed by analysis utilizing liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) using collision-induced dissociation (CID) and electron-activated dissociation (EAD) approaches. We have confidently identified 13 metabolites. Time course profiles of parent and metabolite peaks are consistent with sequential enzymatic cleavage pattern. The 13 metabolites mapped to 8 cleavage sites. Most of these cleavage sites can be explained by the specificity of digestive enzymes, e.g. trypsin, pepsin, and elastase. However, α-methyl-L-phenylalanine appeared to be well protected from chymotrypsin and pepsin digestion since no cleavage peptides ending with α-methyl-L-phenylalanine were observed. These study results provide further structural details explaining previously published stability data and provide new insights into potential GLP1 proteolytic liabilities for future engineering.