Systematic analytical workflow for characterisation and identification of partially reduced species in monoclonal antibody manufacturing.

Fragmentation is a major degradation pathway ubiquitous to all therapeutic monoclonal antibody (mAb) and therefore, monitored throughout the manufacturing process. Here, we describe a three-step approach to 1) detect, 2) confirm and 3) characterize partially reduced fragment species in an immunoglobulin G1 (IgG1) mAb with prolonged hold time of harvested cell culture fluid (HCCF). Microchip capillary electrophoresis (MCE) and high-performance size exclusion chromatography (HPSEC) were used as fast and efficient screening methods to detect fragmentation. HPSEC was found to be underestimating fragmentation levels. To confirm and characterize the fragments, capillary electrophoresis-sodium dodecyl sulphate (CE-SDS) was employed. Interestingly, the absence of fragments in the reduced CE-SDS analysis suggested partial reduction of disulphide bonds contributing to fragmentation in this mAb lot. This was further confirmed using reverse phase high performance liquid chromatography (RP-HPLC) coupled with mass spectrometry, which established the presence of heavy-heavy-light (HHL), heavy-heavy (HH), light-light dimer (LL), light chain (LC) and half antibody (HL) fragments with good mass accuracy. In this study, we demonstrated a readily applicable systematic strategy to support process development and investigate anomalous events in manufacturing. An additional highlight of this work is the data-driven comprehensive comparison of modern and conventional analytical techniques for fragment analysis.

CLINICAL CHARACTERISTICS OF PATIENTS WITH TYPE 2 DIABETES MELLITUS CONTINUED ON ORAL ANTIDIABETES MEDICATIONS IN THE HOSPITAL.

Objective: Basal/basal-bolus insulin with discontinuation of home oral antidiabetes medications (OADs) is the preferred method to achieve glycemic control in many hospitalized patients. We hypothesized that a subset of patients with type 2 diabetes mellitus (T2DM) can achieve an acceptable level of blood sugar control without cessation of their OADs when hospitalized. Methods: A retrospective chart review was conducted on patients with T2DM who were only on OADs at home, admitted to Fairview Hospital, a community hospital in the Cleveland Clinic Health System. We divided patients into those whose OADs were continued (group 1) and those whose OADs were discontinued (group 2), with or without the addition of insulin in the hospital. Blood glucose (BG) levels and patient characteristics were compared. Results: There were 175 patients, 73 in group 1 and 102 in group 2. The percentage of patients achieving all BG values within 100 to 180 mg/dL was the same between group 1 (21.9%) and group 2 (23.8%) (P = .78). Mean BG was similar between group 1 and group 2 (146.1 ± 41.4 mg/dL versus 152.1 ± 38.9 mg/dL; P = .33), with no significant difference in terms of percentage of patients with hyperglycemia or hypoglycemia. A greater proportion of patients in group 1 had an uninterrupted feeding status, nonintensive care unit admission and no contrast dye exposure, and a shorter length of stay. Conclusion: Our study shows that patients with certain characteristics could achieve an acceptable level of glycemic control without cessation of their home OADs. Abbreviations: BG = blood glucose; DPP-4 = dipeptidyl dipeptidase 4; GFR = glomerular filtration rate; HbA1c = hemoglobin A1c; ICU = intensive care unit; LOS = length of stay; NPO = nil per os; OAD = oral antidiabetes medication; POC = point of care; T2DM = type 2 diabetes mellitus.

Design, synthesis, and optimization of novel epoxide incorporating peptidomimetics as selective calpain inhibitors.

Hyperactivation of the calcium-dependent cysteine protease calpain 1 (Cal1) is implicated as a primary or secondary pathological event in a wide range of illnesses and in neurodegenerative states, including Alzheimer's disease (AD). E-64 is an epoxide-containing natural product identified as a potent nonselective, calpain inhibitor, with demonstrated efficacy in animal models of AD. By use of E-64 as a lead, three successive generations of calpain inhibitors were developed using computationally assisted design to increase selectivity for Cal1. First generation analogues were potent inhibitors, effecting covalent modification of recombinant Cal1 catalytic domain (Cal1cat), demonstrated using LC-MS/MS. Refinement yielded second generation inhibitors with improved selectivity. Further library expansion and ligand refinement gave three Cal1 inhibitors, one of which was designed as an activity-based protein profiling probe. These were determined to be irreversible and selective inhibitors by kinetics studies comparing full length Cal1 with the general cysteine protease papain.

Proteomic and mass spectroscopic quantitation of protein S-nitrosation differentiates NO-donors.

Protein S-nitrosation has been argued to be the most important signaling pathway mediating the bioactivity of NO. This post-translational modification of protein thiols is the result of chemical nitrosation of cysteine residues. The term NO-donors covers very different chemical classes, from clinical therapeutics to probes of routine use in chemical biology; their different chemistry is predicted to result in distinctive biology regulated by protein S-nitrosation. To measure the extent of protein S-nitrosation by NO-donors, a proteomic mass spectrometry method was developed, which quantitates free thiol versus nitrosothiol for each modified cysteine residue, coined d-Switch. This method is adapted from the biotin switch (BST) method, used extensively to identify S-nitrosated proteins in complex biological mixtures; however, BST does not quantitate free thiol. Since glutathione-S-transferase P1-1 (GST-P1) has been proposed to be a biological "NO-carrier", GST-P1 was used as a reporter protein. The 5 different chemical classes of NO-donors compared by d-Switch demonstrated very different profiles of protein S-nitrosation and response to O(2) and cysteine, although all NO-donors were oxidants toward GST-P1. The low limits of detection and the ability to use established MS database searching allowed facile generalization of the d-Switch method. Therefore after incubation of neuronal cell cultures with nitrosothiol, it was possible to quantitate not only S-nitrosation of GST-P1 but also many other proteins, including novel targets such as ubiquitin carboxyl-terminal esterase L1 (UCHL1). Moreover, d-Switch also allowed identification of non-nitrosated proteins and quantitation of degree of nitrosation for individual protein thiols.

Nitrates and NO-NSAIDs in cancer chemoprevention and therapy: in vitro evidence querying the NO donor functionality.

Properties of the NO-ASA family of NO-donating NSAIDs (NO-NSAIDs), notably NCX 4016 (mNO-ASA) and NCX 4040 (pNO-ASA), reported in more than one hundred publications, have included positive preclinical data in cancer chemoprevention and therapy. Evidence is presented that the antiproliferative, the chemopreventive (antioxidant/electrophile response element (ARE) activation), and the anti-inflammatory activity of NO-ASA in cell cultures is replicated by X-ASA derivatives that are incapable of acting as NO donors. pBr-ASA and mBr-ASA are conisogenic with NO-ASA, but are not NO donors. The biological activity of pNO-ASA is replicated by pBr-ASA; and both pNO-ASA and pBr-ASA are bioactivated to the same quinone methide electrophile. The biological activity of mNO-ASA is replicated by mBr-ASA; mNO-ASA and mBr-ASA are bioactivated to different benzyl electrophiles. The observed activity is likely initiated by trapping of thiol biomolecules by the quinone and benzyl electrophiles, leading to depletion of GSH and modification of Cys-containing sensor proteins. Whereas all NO-NSAIDs containing the same structural "linker" as NCX 4040 and NCX 4016 are anticipated to possess activity resulting from bioactivation to electrophilic metabolites, this expectation does not extend to other linker structures. Nitrates require metabolic bioactivation to liberate NO bioactivity, which is often poorly replicated in vitro, and NO bioactivity provided by NO-NSAIDs in vivo provides proven therapeutic benefits in mitigation of NSAID gastrotoxicity. The in vivo properties of X-ASA drugs await discovery.

Quinone formation as a chemoprevention strategy for hybrid drugs: balancing cytotoxicity and cytoprotection.

Cellular defense mechanisms that respond to damage from oxidative and electrophilic stress, such as from quinones, represent a target for chemopreventive agents. Drugs bioactivated to quinones have the potential to activate antioxidant/electrophile responsive element (ARE) transcription of genes for cytoprotective phase 2 enzymes such as NAD(P)H-dependent quinone oxidoreductase (NQO1) but can also cause cellular damage. Two isomeric families of compounds were prepared, including the NO-NSAIDs (NO-donating nonsteroidal anti-inflammatory drugs) NCX 4040 and NCX 4016; one family was postulated to release a quinone methide on esterase bioactivation. The study of reactivity and GSH conjugation in model and cell systems confirmed the postulate. The quinone-forming family, including NCX 4040 and conisogenic bromides and mesylate, was rapidly bioactivated to a quinone, which gave activation of ARE and consequent induction of NQO1 in liver cells. Although the control family, including NCX 4016 and conisogenic bromides and mesylates, cannot form a quinone, ARE activation and NQO1 induction were observed, compatible with slower SN2 reactions with thiol sensor proteins, and consequent ARE-luciferase and NQO1 induction. Using a Chemoprevention Index estimate, the quinone-forming compounds suffered because of high cytoxicity and were more compatible with cancer therapy than chemoprevention. In the Comet assay, NCX 4040 was highly genotoxic relative to NCX 4016. There was no evidence that NO contributes to the observed biological activity and no evidence that NCX 4040 is an NO donor, instead, rapidly releasing NO3- and quinone. These results indicate a strategy for studying the quinone biological activity and reinforce the therapeutic attributes of NO-ASA through structural elements other than NO and ASA.