Matching pH values for antibody stabilization and crystallization suggest rationale for accelerated development of biotherapeutic drugs.

Monoclonal antibodies (mAbs) are currently leading products in the global biopharmaceutical market. Multiple mAbs are in clinical development and novel biotherapeutic protein scaffolds, based on the canonical immunoglobulin G (IgG) fold, are emerging as treatment options for various medical conditions. However, fast approvals for biotherapeutics are challenging to achieve, because of difficult scientific development procedures and complex regulatory processes. Selecting molecular entities with superior physicochemical properties that proceed into clinical trials and the identification of stable formulations are crucial developability aspects. It is widely accepted that the solution pH has critical influences on both the protein's colloidal stability and its crystallization behavior. Furthermore, proteins usually crystallize best at solution conditions that enable high protein solubility, purity, stability, and monodispersity. Therefore, we hypothesize that the solution pH value is a central parameter that is linking together protein formulation, protein crystallization, and thermal protein stability. In order to experimentally test this hypothesis, we have investigated the effect of the solution pH on the thermal stabilities and crystallizabilities for three different mAbs. Combining biophysical measurements with high throughput protein (HTP) crystallization trials we observed a correlation in the buffer pH values for eminent mAb stability and successful crystallization. Specifically, differential scanning fluorimetry (DSF) was used to determine pH values that exert highest thermal mAb stabilities and additionally led to the identification of unfolding temperatures of individual mAb domains. Independently performed crystallization trials with the same mAbs resulted in their successful crystallization at pH values that displayed highest thermal stabilities. In summary, the presented results suggest a strategy how protein crystallization could be used as a screening method for the development of biotherapeutic protein formulations with improved in vitro stabilities.

Standardization of the Reconstitution Procedure of Protein Lyophilizates as a Key Parameter to Control Product Stability.

Lyophilization of protein formulations is an essential tool for stabilization and is becoming increasingly important for pharmaceutical development. Reconstitution of the lyophilized cakes is crucial to obtain an applicable product. Nowadays, manual reconstitution by patients or medical staff is the common method defined in instructions for marketed lyophilized drug products. Even though this step is influencing the quality of the final solution, it can represent a challenge to develop a standardized manual protocol and the performance is highly dependent on human factors. This study summarizes the implementation and performance of controlled reconstitution studies for protein lyophilizates applying a mechanical reconstitution device. Using automated and standardized protocols, reconstitution time of a bispecific antibody lyophilizate could be reduced effectively from 25 to below 5 min compared to the predeveloped manual protocol. It was shown that the reconstitution protocol is influencing the stability of sensitive proteins. Monomer content as well as formation of subvisible particles differed considerably between the tested protocols emphasizing the relevance of standardized procedures.

Protein-Excipient Interactions Evaluated via Nuclear Magnetic Resonance Studies in Polysorbate-Based Multidose Protein Formulations: Influence on Antimicrobial Efficacy and Potential Study Approach.

Preservatives are excipients essentially needed in pharmaceutical multidose formulations to prevent microbial growth. Among available substances, phenol is widely used for parenterals; however, it is known to interact with nonionic surfactants like polysorbate and potentially with the active pharmaceutical ingredient. Although the need for combinations of surfactants and preservatives is growing, to date possible molecular interactions which can eventually weaken the stability and antimicrobial activity of the formulation are not yet well understood and properly investigated. In the current study, the binding of phenol to a model fusion protein as well as to polysorbate 20 was investigated. For this purpose, the fraction of bound phenol was successfully quantified via diffusion ordered nuclear magnetic resonance spectroscopy. The binding of phenol to the surfactant is negligible in pharmaceutically relevant polysorbate concentrations, but the binding to the employed active pharmaceutical ingredient was relevant and concentration dependent. The resulting consequence of this interaction was the decrease of the antimicrobial efficacy. As a final outcome of this study, nuclear magnetic resonance analysis is proposed as a material saving method to be used in combination with the antimicrobial activity testing described in the Pharmacopeias.

Non-aqueous suspensions of antibodies are much less viscous than equally concentrated aqueous solutions.

PURPOSE: The aim of this study was to markedly lower the viscosities of highly concentrated protein, in particular antibody, formulations. An effective approach elaborated herein for γ-globulin and a monoclonal antibody is to replace aqueous solutions with equimolar suspensions in neat organic solvents. METHODS: Viscosities of aqueous solutions and non-aqueous suspensions of the model protein bovine γ-globulin and a murine monoclonal antibody were examined under a variety of experimental conditions. In addition, protein particle sizes were measured using dynamic light scattering and light microscopy. RESULTS: Concentrated suspensions of amorphous γ-globulin powders (up to 300 mg/mL, composed of multi-micron-sized particles) in absolute ethanol and a number of other organic solvents were found to have viscosities up to 38 times lower than the corresponding aqueous solutions. Monoclonal antibody follows the same general trend. Additionally, the higher the protein concentration and lower the temperature, the greater the viscosity benefit of a suspension over a solution. CONCLUSIONS: The viscosities of concentrated γ-globulin and monoclonal antibody suspensions in organic solvents are drastically reduced compared to the corresponding aqueous solutions; the magnitude of this reduction depends on the solvent, particularly its hydrogen-bonding properties.