Intentional overdose of glargine insulin: Determination of the parent compound in postmortem blood by LC-HRMS.

Insulin glargine is a long-acting insulin analog that is converted after enzymatic cleavage of the arginine pair of the ß-chain into its main metabolite M1 (21A -Gly-insulin), which is responsible for the hypoglycemic activity. In all the overdose cases described in the literature, only M1 concentrations have been reported, whereas insulin glargine was always absent or below the limit of quantitation. In this study, we present a case of suicide of a young nurse by injection of insulin glargine in which the parent molecule was found at a toxic concentration in blood. The determination and the discrimination of insulin glargine from human insulin and other synthetic analogs in the blood specimen were performed by liquid chromatography coupled to high-resolution mass spectrometry (Waters XEVO G2-XS QToF) and extraction after precipitation in the presence of bovine insulin (internal standard), with a mixture of acetonitrile/methanol +1% formic acid followed by purification on solid phase extraction cartridges C18. Glargine insulin tested highly positive in the blood with a concentration of 1.06 mg/L. Due to the difficulty in obtaining a M1 pure standard, the metabolite could not be dosed. This unique presence of the parent molecule, reported for the first time, can be explained by inter-individual variability in the rate of conversion to metabolite. Intravenous injection versus subcutaneous injection can also explain the presence of insulin glargine. Finally, the dose injected may have been so high that saturation of the proteolytic enzymes responsible for conversion to M1 should have occurred.

Caveolin-1 Is Essential for the Improvement of Insulin Sensitivity through AKT Activation during Glargine Treatment on Diabetic Mice.

Insulin treatment was confirmed to reduce insulin resistance, but the underlying mechanism remains unknown. Caveolin-1 (Cav-1) is a functional protein of the membrane lipid rafts, known as caveolae, and is widely expressed in mammalian adipose tissue. There is increasing evidence that show the involvement of Cav-1 in the AKT activation, which is responsible for insulin sensitivity. Our aim was to investigate the effect of Cav-1 depletion on insulin sensitivity and AKT activation in glargine-treated type 2 diabetic mice. Mice were exposed to a high-fat diet and subject to intraperitoneal injection of streptozotocin to induce diabetes. Next, glargine was administered to treat T2DM mice for 3 weeks (insulin group). The expression of Cav-1 was then silenced by injecting lentiviral-vectored short hairpin RNA (shRNA) through the tail vein of glargine-treated T2DM mice (CAV1-shRNA group), while scramble virus injection was used as a negative control (Ctrl-shRNA group). The results showed that glargine was able to upregulate the expression of PI3K and activate serine phosphorylation of AKT through the upregulation of Cav-1 expression in paraepididymal adipose tissue of the insulin group. However, glargine treatment could not activate AKT pathway in Cav-1 silenced diabetic mice. These results suggest that Cav-1 is essential for the activation of AKT and improving insulin sensitivity in type 2 diabetic mice during glargine treatment.

Buried Kex2 Sites in Glargine Precursor Aggregates Prevent Its Intracellular Processing in Pichia pastoris Muts Strains and the Effect of Methanol-Feeding Strategy and Induction Temperature on Glargine Precursor Production Parameters.

Glargine is a long-acting insulin analog with less hypoglycemia risk. Like human insulin, glargine is a globular protein composed of two polypeptide chains linked by two disulfide bonds. Pichia pastoris KM71 Muts strains were engineered to produce and secrete insulin glargine through the cleavage of two Kex2 sites. Nevertheless, the recombinant product was the single-chain insulin glargine (glargine precursor) instead of the expected double-chain glargine. Molecular model analysis of the dimeric and hexameric forms of the single-chain glargine showed buried Kex2 sites that prevent intracellular glargine precursor processing. The effect of the methanol-feeding strategy (methanol limited fed-batch vs. methanol non-limited fed-batch) and the induction temperature (28 °C vs. 24 °C) on the cell growth and production parameters in bioreactor cultures was also evaluated. Exponential growth at a constant specific growth rate was observed in all the cultures. The volumetric productivities and specific substrate consumption rates were directly proportional to the specific growth rate. The lower temperature led to increased metabolic activity of the yeast cells, which increased the specific growth rate. The methanol non-limited fed-batch culture at 24 °C showed the highest values for the process parameters. After 75 h of induction, 0.122 g/L of glargine precursor was obtained from the culture medium.

Update on Biosimilar Insulins: A US Perspective.

The development of biosimilar insulin products has slowly evolved with only two follow-on biologics currently available to patients in the US. Both Basaglar® (insulin glargine) and Admelog® (insulin lispro) have undergone extensive testing, and have gained significant use by patients in the US. Despite the availability of these follow-on products, the price of insulin has remained stubbornly high. New regulatory guidance under the Biologics Price Competition and Innovations Act that came into effect in March 2020 introduced an abbreviated pathway for the approval of biosimilar insulins and introduced the option to apply for interchangeability of the biosimilar insulin with the reference product. This abbreviated clinical testing may open the doors for numerous follow-on insulin products, with unknown supply-chain and fiscal ramifications. This review will highlight the development process of biosimilar insulin in the US and the recent regulatory changes that can aid this process. We will also discuss challenges for prescribers and patients who are navigating this ever-changing landscape. These new regulations for biosimilar insulins will have ramifications for patients, healthcare providers, and third-party payers, though the direction and scope of these changes is unclear.

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[D10]Leu-glargine and 4[D10]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.

Nonclinical pharmacology and toxicology of the first biosimilar insulin glargine drug product (BASAGLAR®/ABASAGLAR®) approved in the European Union.

Basaglar®/Abasaglar® (Lilly insulin glargine [LY IGlar]) is a long-acting human insulin analogue drug product granted marketing authorisation as a biosimilar to Lantus® (Sanofi insulin glargine [SA IGlar]) by the European Medicines Agency. We assessed the similarity of LY IGlar to the reference drug product, European Union-sourced SA IGlar (EU-SA IGlar), using nonclinical in vitro and in vivo studies. No biologically relevant differences were observed for receptor binding affinity at either the insulin or insulin-like growth factor-1 (IGF-1) receptors, or in assays of functional or de novo lipogenic activity. The mitogenic potential of LY IGlar and EU-SA IGlar was similar when tested in both insulin- and IGF-1 receptor dominant cell systems. Repeated subcutaneous daily dosing of rats for 4 weeks with 0, 0.3, 1.0, or 2.0 mg/kg LY IGlar and EU-SA IGlar produced mortalities and clinical signs consistent with severe hypoglycaemia. Glucodynamic profiles of LY IGlar and EU-SA IGlar in satellite animals showed comparable dose-related hypoglycaemia. Severe hypoglycaemia was associated with axonal degeneration of the sciatic nerve; the incidence and severity were low and did not differ between LY IGlar and EU-SA IGlar. These results demonstrated no biologically relevant differences in toxicity between LY IGlar and EU-SA IGlar.

Recombinant Glargine Insulin Production Process Using Escherichia coli.

Glargine insulin is a long-acting insulin analog that helps blood glucose maintenance in patients with diabetes. We constructed the pPT-GI vector to express prepeptide glargine insulin when transformed into Escherichia coli JM109. The transformed E. coli cells were cultured by fed-batch fermentation. The final dry cell mass was 18 g/l. The prepeptide glargine insulin was 38.52% of the total protein. It was expressed as an inclusion body and then refolded to recover the biological activity. To convert the prepeptide into glargine insulin, citraconylation and trypsin cleavage were performed. Using citraconylation, the yield of enzymatic conversion for glargine insulin increased by 3.2-fold compared with that without citraconylation. After the enzyme reaction, active glargine insulin was purified by two types of chromatography (ion-exchange chromatography and reverse-phase chromatography). We obtained recombinant human glargine insulin at 98.11% purity and verified that it is equal to the standard of human glargine insulin, based on High-performance liquid chromatography analysis and Matrix-assisted laser desorption/ionization Time-of-Flight Mass Spectrometry. We thus established a production process for high-purity recombinant human glargine insulin and a method to block Arg (B31)-insulin formation. This established process for recombinant human glargine insulin may be a model process for the production of other human insulin analogs.

Disruption of KEX1 gene reduces the proteolytic degradation of secreted two-chain Insulin glargine in Pichia pastoris.

Insulin glargine is a slow acting analog of insulin used in diabetes therapy. It is produced by recombinant DNA technology in different hosts namely E. coli and Pichia pastoris. In our previous study, we have described the secretion of fully folded two-chain Insulin glargine into the medium by over-expression of Kex2 protease. The enhanced levels of the Kex2 protease was responsible for the processing of the glargine precursor with in the host. Apart from the two-chain glargine product we observed a small proportion of arginine clipped species. This might be due to the clipping of arginine present at the C-terminus of the B-chain as it is exposed upon Kex2 cleavage. The carboxypeptidase precursor Kex1 is known to be responsible for clipping of C-terminal lysine or arginine of the proteins or peptides. In order to address this issue we created a Kex1 knock out in the host using Cre/loxP mechanism of targeted gene deletion. When two-chain glargine was expressed in the Kex1 knock out host of P. pastoris GS115 the C-terminal clipped species reduced by ∼80%. This modification further improved the process by reducing the levels of product related impurities.

Effect of insulin analogues on phosphatidyl inositol-3 kinase/Akt signalling in INS-1 rat pancreatic derived ß-cells.

CONTEXT: Insulin analogues are largely used for the treatment of diabetic patients, but concerns have been raised about their mitogenic/anti-apoptotic potential. It is therefore important to evaluate these analogues in different cell systems. OBJECTIVE: The aim of this work was to establish the pharmacological profiles of insulin analogues towards PI-3 kinase/Akt pathway in INS-1 ß-pancreatic cells. METHODS: Bioluminescence Resonance Energy Transfer (BRET), in cell western and caspase 3/7 assays, was used to study the effects of ligands. RESULTS: Among the five analogues evaluated, only glargine stimulated PI-3 kinase/Akt pathway with higher efficiency than insulin, whereas glargine's metabolite M1 was less efficient. However, glargine did not show higher anti-apoptotic efficiency than insulin. CONCLUSION: Glargine was more efficient than insulin for the activation of PI-3 kinase/Akt pathway, but not for the inhibition of caspase 3/7 activity. Moreover, glargine's metabolite M1 displayed lower efficiency than insulin towards PI-3 kinase/Akt activation and caspase 3/7 inhibition.

Insulin glargine metabolite 21(A) -Gly-human insulin (M1) is the principal component circulating in the plasma of young children with type 1 diabetes: results from the PRESCHOOL study.

BACKGROUND AND AIMS: Insulin glargine metabolite 21(A) -Gly-human insulin (M1) is the principal component circulating in plasma of adults with type 1 diabetes. The objective of this study was to confirm this finding in young children and to rule out accumulation of parent insulin glargine. DESIGN AND METHODS: Children with type 1 diabetes from the PRESCHOOL study, aged 2-6 yr, were treated with insulin glargine for 24 wk (n = 62). Blood samples were drawn at weeks 1, 2, and 4 approximately 24 h after the last dose and analyzed for glargine, M1, and Thr(30B) -des-M1 (M2) using immunoaffinity purification and liquid chromatography with mass spectrometry. The lower limit of quantification was 33 pmol/L for all analytes. RESULTS: M1 was the principal active component circulating in plasma. Mean (SD) plasma Ctrough values were 101 (138), 80 (122), and 79 (102) pmol/L following glargine doses of 0.33 (0.02), 0.34 (0.02), and 0.38 (0.03) U/kg at weeks 1, 2, and 4, respectively. Parent insulin glargine and M2 concentrations were below the level of quantification. These results are in line with those observed in adults and indicate no accumulation of the parent compound in this patient population. CONCLUSION: In young children with type 1 diabetes, the principal component circulating in plasma after subcutaneous injection of insulin glargine is M1, the pharmacologically active component. No accumulation of the parent insulin glargine was observed. These data provide additional evidence on the safety profile of insulin glargine in young children (Clinical trial identifier: NCT00993473).