Design of experiment and statistical analyses were applied to evaluate the effects of several formulation components on the thermal and colloidal stability for a series of monoclonal antibody (mAb) ...formulations. The high‐throughput assessment of the protein stability was performed by measuring the temperature of hydrophobic exposure (Th, thermal stability) and the diffusion interaction parameter (kD, colloidal stability). To correlate the measured parameters with protein stability, the propensity to aggregate was tested by exposing the mAb samples to two types of stress: mechanical stress caused by shaking agitation and thermal stress. Mechanical stress led to increased formation of large particles, whereas temperature stress resulted in an increase in oligomers. The data obtained from the stress studies were used to determine the critical values for the stability parameters. The optimal formulation compositions were determined based on the statistical models and the predication tests. This approach of high‐throughput thermal and colloidal stability screening can be applied to the characterization and prediction of protein formulation properties.
More therapeutic monoclonal antibodies and antibody-based modalities are in development today than ever before, and a faster and more accurate drug discovery process will ensure that the number of ...candidates coming to the biopharmaceutical pipeline will increase in the future. The process of drug product development and, specifically, formulation development is a critical bottleneck on the way from candidate selection to fully commercialized medicines. This article reviews the latest advances in methods of formulation screening, which allow not only the high-throughput selection of the most suitable formulation but also the prediction of stability properties under manufacturing and long-term storage conditions. We describe how the combination of automation technologies and high-throughput assays creates the opportunity to streamline the formulation development process starting from early preformulation screening through to commercial formulation development. The application of quality by design (QbD) concepts and modern statistical tools are also shown here to be very effective in accelerated formulation development of both typical antibodies and complex modalities derived from them.
We propose a new method to measure the viscosity of concentrated protein solutions in a high-throughput format. This method measures the apparent hydrodynamic radius of polystyrene beads with known ...sizes using a dynamic light scattering (DLS) system with a microplate reader. Glycerol solution viscosities obtained by the DLS method were in good agreement with those reported in the literature. Viscosity of the solutions of two monoclonal antibody molecules was acquired using both DLS and cone-and-plate techniques, and the results were comparable. The DLS method described here has the potential to be used in many aspects of protein characterization.
The first endocannabinoid, anandamide, was discovered in 1992. Since then, two other endocannabinoid agonists have been identified, 2-arachidonyl glycerol and, more recently, noladin ether. Here, we ...report the identification and pharmacological characterization of a novel endocannabinoid, virodhamine, with antagonist properties at the CB1 cannabinoid receptor. Virodhamine is arachidonic acid and ethanolamine joined by an ester linkage. Concentrations of virodhamine measured by liquid chromatography atmospheric pressure chemical ionization-tandem mass spectrometry in rat brain and human hippocampus were similar to anandamide. In peripheral tissues that express the CB2 cannabinoid receptor, virodhamine concentrations were 2- to 9-fold higher than anandamide. In contrast to previously described endocannabinoids, virodhamine was a partial agonist with in vivo antagonist activity at the CB1 receptor. However, at the CB2 receptor, virodhamine acted as a full agonist. Transport of (14)Canandamide by RBL-2H3 cells was inhibited by virodhamine. Virodhamine produced hypothermia in the mouse and acted as an antagonist in the presence of anandamide both in vivo and in vitro. As a potential endogenous antagonist at the CB1 receptor, virodhamine adds a new form of regulation to the endocannabinoid system.
The purpose of this study was to demonstrate the utility of combining a design of experiment (DOE) approach with high-throughput formulation screening to identify the main factors affecting protein ...thermostability and solution viscosity. The optimization of buffer compositions was guided by statistical analysis of the data to obtain the targeted combination of low viscosity and high thermostability. Different monoclonal antibody (mAb) formulation variables were evaluated in the study to achieve optimization of two parameters: (i) thermostability characterized by temperature of hydrophobic exposure and (ii) viscosity. High-throughput measurements were employed to characterize both parameters. The significance of each factor and the two-way interactions between them was studied by multivariable regression analysis. An experimental design was used to estimate the significance of all factors, including interaction effects. The range of optimal buffer compositions that maximized thermostability and minimized viscosity of a mAb formulation was determined. The described high-throughput methods are well suited for characterization of multiple protein formulation compositions with minimized resources such as time and material. The DOE approach can be successfully applied to the screening of mAb formulations early in the development lifecycle.
Protein stability, one of the major concerns for therapeutic protein development, can be optimized during process development by evaluating multiple formulation conditions. This can be a costly and ...lengthy procedure where different excipients and storage conditions are tested for their impact on protein stability. A better understanding of the effects of different formulation conditions at the molecular level will provide information on the local interactions within the protein leading to a more rational design of stable and efficacious formulations. In this study, we examined the roles of the excipients, sucrose and benzyl alcohol, on the conformational dynamics of recombinant human granulocyte colony stimulating factor using hydrogen/deuterium exchange coupled with mass spectrometry (HDX-MS). Under physiological pH and temperature, sucrose globally protects the whole molecule from deuterium uptake, whereas benzyl alcohol induces increased deuterium uptake of the regions within the α-helical bundle, with even larger extent. The HDX experiments described were incorporated a set of internal peptides (Zhang et al., 2012. Anal Chem 84:4942-4949) to monitor the differences in intrinsic exchange rates in different formulations. In addition, we discussed the feasibility of implementing HDX-MS with these peptide probes in protein formulation development.
Human kallikrein 6 (hK6) is a trypsin-like serine protease, member of the human kallikrein gene family. Studies suggested a potential involvement of hK6 in the development and progression of ...Alzheimer’s disease. The serum levels of hK6 might be used as a biomarker for ovarian cancer. To gain insights into the physiological role of this enzyme, we sought to determine its substrate specificity and its interactions with various inhibitors. We produced the proform of hK6 and showed that this enzyme was able to autoactivate, as well as proteolyse itself, leading to inactivation. Kinetic studies indicated that hK6 cleaved with much higher efficiency after Arg than Lys and with a preference for Ser or Pro in the P2 position. The efficient degradation of fibrinogen and collagen types I and IV by hK6 indicated that this kallikrein might play a role in tissue remodeling and/or tumor invasion and metastasis. We also demonstrated proteolysis of amyloid precursor protein by hK6 and determined the cleavage sites at the N-terminal end of the protein. Inhibition of hK6 was achieved via binding to different serpins, among which antithrombin III was the most efficient.
Discovery and successful development of biopharmaceutical products depend on a thorough characterization of the molecule both before and after formulation. Characterization of a formulated ...biotherapeutic, typically a protein or large peptide, requires a rigorous assessment of the molecule's physical stability. Stability of a biotherapeutic includes not only chemical stability, i.e., degradation of the molecule to form undesired modifications, but also structural stability, including the formation of aggregates. In this review, high throughput biophysical characterization techniques are described according to their specific applications during biopharmaceutical discovery, development and manufacturing. The methods presented here are classified according to these attributes, and include spectroscopic assays based on absorbance, polarization, intrinsic and extrinsic fluorescence, surface plasmon resonance instrumentation, calorimetric methods, dynamic and static light scattering techniques, several visible particle counting and sizing methods, new viscosity assay, based on light scattering and mass spectrometry. Several techniques presented here are already implemented in industry; but, many high throughput biophysical methods are still in the initial stages of implementation or even in the prototype stage. Each technique in this report is judged by the specific application of the method through the biopharmaceutical development process.
To measure co-expression of EGFR and Ki67 proteins in pretreatment tumor biopsies of anal cancer patients enrolled on NRG Oncology RTOG 9811, a phase III trial comparing ...5-fluorouracil/mitomycin-C/radiation therapy (Arm A) versus 5-fluorouracil/cisplatin/radiation therapy (Arm B), and to correlate expression with clinical outcome.
EGFR and Ki67 co-expression was measured after constructing a tissue microarray using fluorescence immunohistochemistry and automated quantitative image analysis. The Ki67 score within EGFR high versus low areas (Ki67ratio in EGFR
) in each tumor core was analyzed at the median, quartiles, and as a continuous variable. Associations between the tumor markers and clinical endpoints (overall and disease-free survival, locoregional and colostomy failure, and distant metastases) were explored.
A total of 282 pretreatment tumors were analyzed from NRG Oncology RTOG 9811. Of evaluated specimens, 183 (65%, n=89, Arm A; n=94, Arm B) were eligible and analyzable. There were no significant differences in baseline characteristics or outcomes between analyzable and unanalyzable patient cases. Median follow-up was 6.0 years. On multivariate analysis, after adjusting for gender, patients with Ki67ratio in EGFR
≥median had worse overall survival (hazard ratio 2.41, 95% confidence interval 1.38-4.19, P=.0019). After adjusting for N stage and largest tumor dimension, patients with Ki67ratio in EGFR
≥ median had a higher risk of a disease-free failure (hazard ratio 1.85, 95% confidence interval 1.18-2.92, P=.0078). Technical validation with an independent anal cancer patient cohort was performed and shows a very similar biomarker score distribution.
High Ki67ratio in EGFR
is associated with worse clinical outcome in this subset of patients with anal cancer treated with chemoradiation on NRG Oncology RTOG 9811. Evaluation within a clinical trial will be required to determine whether patients with these tumor characteristics may specifically benefit from an EGFR-targeted therapeutic agent.
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