Mixing of a mAb Formulation in a New Magnetically Coupled Single-Use Mixing System: Key Learnings of Preliminary Experimental and Computational Evaluation.

MilliporeSigma recently introduced a new magnetically coupled single-use mixing system (Mobius® Power MIX) for more efficient mixing of buffers and media in biopharmaceutical applications. Experimental and computational fluid dynamics (CFD) assessments were performed on the Power MIX 100 system to understand product quality impact, shear, and mixing efficiency. It was interesting to note slightly higher submicron (0.4-1 µm) and subvisible (1-54 µm) particle formation at the lower mixing speed (50 RPM) compared to higher mixing speeds (100/200 RPM). Mixing speed and time showed negligible impact on the other product quality attributes tested, including protein concentration, turbidity, general appearance, purity, and soluble aggregates. The CFD simulations provided useful information with respect to the impact of batch size (20-100 L), viscosity (2-50 cP), and impeller speed (100-300 RPM) on mixing time (mixing time ranged from 10 to 365 s) and shear (maximum shear rate was found to be localized around the impeller and it was about 30,260 s-1, whereas the average shear rate ranged from 4 to 36 s-1). Statistical analysis of the CFD results showed that natural-log transformation and quadratic fitting were found to be suitable statistical models to predict mixing time and shear within the design space of the parameters assessed in the present study.

Syringe Filling of a High-Concentration mAb Formulation: Experimental, Theoretical, and Computational Evaluation of Filling Process Parameters That Influence the Propensity for Filling Needle Clogging.

This article summarizes experimental, theoretical, and computational assessments performed to understand the effect of filling and suck-back cycle factors on fluid behaviors that increase the propensity for filling needle clogging. Product drying under ambient conditions decreased considerably when the liquid front was altered from a droplet or meniscus at the needle tip to a point approximately 5 mm inside the needle. Minimizing the variation in size of product droplet formed after the fill cycle is critical to achieve a uniform meniscus height after the suck-back cycle. Several factors were found to contribute to droplet size variability, including filling and suck-back pump speed, suck-back volume, and product temperature. Filling trials and the computational fluid dynamics simulations showed that product meniscus stability during the suck-back cycle can be improved by reducing the suck-back flow rate. The computational fluid dynamics simulations also showed that a decrease in contact angle had the greatest effect in reducing meniscus stability. As the number of filling line stoppages increases, the product buildup at the needle increases. The interaction between stoppages and the number of dispenses between stoppages was established to minimize product buildup at the filling needle. Improved suck-back control was shown to improve process capability of large-scale batches.

Japan-Specific Key Regulatory Aspects for Development of New Biopharmaceutical Drug Products.

Japan represents the third largest pharmaceutical market in the world. Developing a new biopharmaceutical drug product for the Japanese market is a top business priority for global pharmaceutical companies while aligning with ethical drivers to treat more patients in need. Understanding Japan-specific key regulatory requirements is essential to achieve successful approvals. Understanding the full context of Japan-specific regulatory requirements/expectations is challenging to global pharmaceutical companies due to differences in language and culture. This article summarizes key Japan-specific regulatory aspects/requirements/expectations applicable to new drug development, approval, and postapproval phases. Formulation excipients should meet Japan compendial requirements with respect to the type of excipient, excipient grade, and excipient concentration. Preclinical safety assessments needed to support clinical phases I, II, and III development are summarized. Japanese regulatory authorities have taken appropriate steps to consider foreign clinical data, thereby enabling accelerated drug development and approval in Japan. Other important topics summarized in this article include: Japan new drug application-specific bracketing strategies for critical and noncritical aspects of the manufacturing process, regulatory requirements related to stability studies, release specifications and testing methods, standard processes involved in pre and postapproval inspections, management of postapproval changes, and Japan regulatory authority's consultation services available to global pharmaceutical companies.

Syringe Filling of High-Concentration mAb Formulation: Slow Suck-Back Pump Speed Prevented Filling Needle Clogging.

Partial and complete clogging of filling needles occurred during syringe filling of a high-concentration mAb formulation. This caused nonvertical liquid flow, which eventually led to the termination of filling. Overcoming this phenomenon was essential to ensure minimal fill weight variation, product waste, and manufacturing downtime. The liquid behavior inside the filling needle was studied using glass and stainless steel needles and demonstrated that effective suck-back control was critical for preventing needle clogging. A key finding of our work is that the suck-back pump speed was a critical factor to achieve an effective suck back. More specifically, a slow suck-back pump speed (<10 rpm; liquid flow rate, <5 mL/min) was essential to improve suck-back control inside the conventional stainless steel filling needles. In contrast, higher suck-back pump speeds (>10 rpm; liquid flow rate, >5 mL/min) resulted in downward product migration within the filling needle leading to formation of a liquid plug at the needle tip, which was prone to rapid drying. Slowing the suck-back pump speed in conjunction with modifying the suck-back volume was effective at consistently withdrawing product into the stainless steel filling needles and prevented needle clogging.

Protein adsorption, desorption, and aggregation mediated by solid-liquid interfaces.

Adsorption of proteins to solid-fluid interfaces is often empirically found to promote formation of soluble aggregates and larger, subvisible, and visible particles, but key stages in this process are often difficult to probe directly. Aggregation mediated by adsorption to water-silicon oxide (SiOx) interfaces, akin to hydrated glass surfaces, was characterized as a function of pH and ionic strength for alpha-chymotrypsinogen (aCgn) and for a monoclonal antibody (IgG1). A flow cell permitted neutron reflectivity for protein layers adsorbed to clean SiOx surfaces, as well as after successive "rinse" steps. Aggregates recovered in solution after gently "rinsing" the surface were characterized by neutron scattering, microscopy, and fluorescence spectroscopy. IgG1 molecules oriented primarily "flat" against the SiOx surface, with the primary protein layer desorbed to a minimal extent, whereas a diffuse overlayer was easily rinsed off. aCgn molecules were resistant to desorption when they appeared to be unfolded at the interface, but were otherwise easily removed. For cases where strong binding occurred, protein that did desorb was a mixture of monomer and small amounts of HMW aggregates (for aCgn) or subvisible particles (for IgG1). Changes in adsorption and/or unfolding with pH indicated that electrostatic interactions were important in all cases.

Effects of temperature and osmolytes on competing degradation routes for an IgG1 antibody.

Addition of excipients is a common strategy to slow protein aggregation during storage. Excipient effects on the mechanism(s) and temperature (T) dependence of aggregation for a monoclonal antibody solution were tested using size-exclusion chromatography, differential scanning calorimetry (DSC), temperature scanning monomer loss (TSML), and laser light scattering; previous work in buffer-only conditions had shown non-Arrhenius behavior and implicated Fab and/or CH 3 unfolding as a key step in aggregation. Excipients included citrate, amino acid salts (histidine-HCl, arginine-HCl), and polyols (mannitol and glycerol). DSC and TSML showed that Fab, rather than CH 3, unfolding corresponded with the onset of aggregation for each condition. Isothermal incubation at 56.5°C, 40°C, and 2°C-8°C resulted in aggregation, while fragmentation occurred readily at only 40°C. The primary effect of the different excipients appeared to be preferential accumulation/exclusion, affecting the concentrations of partially unfolded monomer key intermediates. In addition, aggregation rates were clearly non-Arrhenius, causing aggregation to dominate over fragmentation at high and low T, and making long-term stability predictions problematic based on commonly employed 40°C conditions. Possible reasons for non-Arrhenius behavior include a strong T-dependence of the Fab unfolding enthalpy and/or a switch from Fab-mediated to Fc-mediated aggregation as one moves from high to low T.

Predicting accelerated aggregation rates for monoclonal antibody formulations, and challenges for low-temperature predictions.

Nonnative aggregation is a common degradation route for therapeutic proteins. Control of aggregate levels inherently requires control and/or prediction of aggregation rates at formulation conditions and storage temperatures of practical interest. Additionally, formulation screening often involves generation of accelerated stability data at one or more temperatures. A temperature-scanning approach for measuring nonnative aggregation rates as a function of temperature is proposed and evaluated here for a monoclonal antibody across different formulation conditions. Observed rate coefficients of aggregation (kobs ) were determined from isothermal kinetic studies for a range of pH and salt conditions at several temperatures, corresponding to shelf lives spanning multiple orders of magnitude. Isothermal kobs values were efficiently and quantitatively predicted by the temperature-scanning monomer loss (TSML) approach at accelerated conditions (half lives of the order 10(-1) -10(2) h). At lower temperatures, non-Arrhenius behavior was apparent in some cases, and was semi-quantitatively described by nonlinear van't Hoff contributions to monomer unfolding free energies. Overall, the results demonstrate a novel strategy to quantitatively determine aggregation rates at time scales of industrial interest, based on kobs values from TSML, which are sample- and time-sparing as compared with traditional isothermal approaches, and illustrate challenges for shelf-life prediction with non-Arrhenius kinetics.

Nonnative aggregation of an IgG1 antibody in acidic conditions, part 2: nucleation and growth kinetics with competing growth mechanisms.

Aggregation mechanisms as a function of pH were assessed for the IgG1 antibody described in Part 1 (Brummitt RK, Nesta DP, Chang L, Chase SF, Laue TM, Roberts CJ. Non-native aggregation of an IGG1 antibody in acidic conditions: 1. Unfolding, colloidal interactions, and high molecular weight aggregate formation. J Pharm Sci. In press). Aggregation kinetics along with static light scattering and size-exclusion chromatography indicated that the aggregate nucleus was a dimer for all conditions tested, and this was semiquantitatively consistent with scaling of the characteristic time scale for nucleation (τ(n)) versus protein concentration at pH 4.5 and pH 5.5. Changing pH significantly altered the mechanism of aggregate growth, as well as the size and solubility of aggregates that were formed. Aggregates at pH 3.5 grew primarily by monomer addition and remained small and soluble. Aggregates at pH 4.5 grew first by chain polymerization, followed by condensation polymerization, leading ultimately to large insoluble particles. At pH 5.5, monomer loss resulted primarily in insoluble aggregate formation, with only low levels of soluble aggregate intermediates detected at early times. The influence of pH on aggregate solubility and the reversibility of aggregate phase separation were confirmed via cloud point titrations. Qualitatively, the global aggregation behavior was consistent with reduction of charge-charge repulsions as a primary factor in promoting larger aggregates and aggregate phase separation.

Nonnative aggregation of an IgG1 antibody in acidic conditions: part 1. Unfolding, colloidal interactions, and formation of high-molecular-weight aggregates.

Monomeric and aggregated states of an IgG1 antibody were characterized under acidic conditions as a function of solution pH (3.5-5.5). A combination of intrinsic/extrinsic fluorescence (FL), circular dichroism, calorimetry, chromatography, capillary electrophoresis, and laser light scattering were used to characterize unfolding, refolding, native colloidal interactions, aggregate structure and morphology, and aggregate dissociation. Lower pH led to larger net repulsive colloidal interactions, decreased thermal stability of Fc and Fab regions, and increased solubility of thermally accelerated aggregates. Unfolding of the Fab domains, and possibly the CH3 domain, was inferred as a key step in the formation of aggregation-prone monomers. High-molecular-weight soluble aggregates displayed nonnative secondary structure, had a semi-rigid chain morphology, and bound thioflavin T (ThT), consistent with at least a portion of the monomer forming amyloid-like structures. Soluble aggregates also formed during monomer refolding under conditions moving from high to low denaturant concentrations. Both thermally and chemically induced aggregates showed similar ThT binding and secondary structural changes, and were noncovalent based on dissociation in concentrated guanidine hydrochloride solutions. Changes in intrinsic FL during chemical versus thermal unfolding suggest a greater degree of structural change during chemical unfolding, although aggregation proceeded through partially unfolded monomers in both cases.