Insulin glargine and its two active metabolites: A sensitive (16pM) and robust simultaneous hybrid assay coupling immunoaffinity purification with LC-MS/MS to support biosimilar clinical studies.

MK-1293 is a newly approved follow-on/biosimilar insulin glargine for the treatment of Type 1 and Type 2 diabetics. To support pivotal clinical studies during biosimilar evaluation, a sensitive, specific and robust liquid chromatography and tandem mass spectrometry (LC-MS/MS) assay for the simultaneous quantification of glargine and its two active metabolites, M1 and M2 were developed. Strategies to overcome analytical challenges, so as to optimize assay sensitivity and improve ruggedness, were evolved, resulting in a fully validated LC-MS/MS method with a lower limit of quantification (LLOQ) at 0.1ng/mL (∼16pM, equivalent to ∼2.8μU/mL) for glargine, M1 and M2, respectively, using 0.5mL of human plasma. The assay employed hybrid methodology that combined immunoaffinity purification and reversed-phase chromatography followed by electrospray-MS/MS detection operated under positive ionization mode. Stable-isotope labeled 6[D]Leu-glargine and 4[D]Leu-M1 were used as internal standards. With a calibration range from 0.1 to 10ng/mL, the intra-run precision (n=5) and accuracy were <6.21%, and 96.9-102.1%, while the inter-run (n=5/run for 7days) precision and accuracy were <9.55% and 96.5-105.1%, respectively, for all 3 analytes. Matrix effect, recovery, analyte stability, and interferences from control matrix, potential concomitant medications and anti-drug antibody were assessed. The assay was fully automated and has been successfully used in support of biosimilar clinical studies. Greater than 94.3% of incurred sample reanalysis (ISR) results met acceptance criteria, demonstrating the robustness of the assay. The strategic considerations during method development and validation are discussed, and can be applied to quantification of other peptides, especially insulin analogs, in the future.