Simultaneous characterization of insulin HMWP and protamine sulphate in complex formulations through SEC-coupled mass spectrometry.

High molecular weight protein aggregates present in a recombinant human insulin and analogs are conventionally quantified by SEC-HPLC and identified by SEC-MALS as oligomeric population which lacks precise identification of species. The limitation of these two techniques is vanquished though simultaneous separation and identification by SEC coupled with MS. The identification was established with organic solvent based isocratic elution followed by MS for parallel separation and identification of HMWP species. The developed SEC-MS method is validated to establish the method capability and variability. Further investigations under stress conditions of Insulin analogues revealed the capability of the method to separate higher order oligomeric (Trimeric, and Tetrameric) species alongside covalent dimeric species. Additionally, the method holds good in separating and sequencing protamine peptides used in suspension (Neutral Protamine Hagedorn) and biphasic/mixed (70/30) formulations of Human insulin using ETD-MSMS. The data presented here shows insight towards utilization of state-of-the-art SEC-MS technique in the biopharmaceutical field as a tool to establish the structural comparability of higher order species in biosimilars and to investigate the lot to lot batch variability for protamine sulphate in-terms of sequence confirmation.

Large scale purification and characterization of A21 deamidated variant-most prominent post translational modification (PTM) for insulins which is also widely observed in insulins pharmaceutical manufacturing and storage.

Biopharmaceutical development demands appropriate understanding of product related variants, which are formed due to post-translational modification and during downstream processing. These variants can lead to low yield, reduced biological activity, and suboptimal product quality. In addition, these variants may undergo immune reactions, henceforth need to be appropriately controlled to ensure consistent product quality and patient safety. Deamidation of insulin is the most common post-translational modification occurring in insulin and insulin analogues. AsnA21 desamido variant is also the most prominent product variant formed during human insulin manufacturing process and/or during the storage. Often, this deamidated variant is used as an impurity standard during in-process and final product analysis in the QC system. However, purification of large quantity of purified deamidated material is always being challenging due to highly similar mass, ionic, hydrophobic properties, and high structural similarity of the variant compared to the parent product. Present work demonstrates the simplified and efficient scalable process for generation of AsnA21 deamidated variant in powder form with ~96% purity. The mixed-mode property of anion exchange resin PolyQuat was utilized to purify the deamidated impurity with high recovery. Subsequent reversed-phase high performance liquid chromatography (RP-HPLC) step was introduced for concentration of product in bind elute mode. Elution pool undergone isoelectric precipitation and lyophilisation. The lyophilized product allows users for convenient use of the deamidated impurity for intended purposes. Detailed characterization by Mass spectrometry revealed deamidation is at AsnA21 and further confirmed that, structural and functional characterization as well as the biological activity of isolated variant is equivalent to insulin.