Investigating the Degradation Behaviors of a Therapeutic Monoclonal Antibody Associated with pH and Buffer Species

How spray drying processing and solution composition can affect the mAbs stability in reconstituted solutions for subcutaneous injections. Part II: Exploring each protein stabilizer effect

Despite extensive research in spray drying of biopharmaceuticals, identifying the optimal formulation composition and process conditions to minimize the various stresses a biopharmaceutical undergoes during this drying process. The current study extends previous research on investigating how spray drying processing and solution composition can affect the stability of monoclonal antibodies (mAbs) in reconstituted solutions for subcutaneous injections. The decoupling process stresses on a model mAb (mAb-A) compared to the effect of coupled spray-drying stresses revealed that excipients and protein concentration had a more pronounced effect on stabilizing mAb-A against shear and thermal/dehydration stresses than spray drying operating conditions. These results prompted the continuation of the study, with the aim to investigate in greater depth the effect of mAb-A concentration in the formulation designated to spray-drying and then the effect of type and the concentration of individual excipients (sugars, amino acids and surfactants). The outcomes of this investigation suggest that a general increase in the concentration of excipients, particularly surfactants, correlates with a reduction in aggregation and turbidity observed in the reconstituted spray-dried mAb-A powders. These results, contribute to the identification of a suitable composition for a spray-dried mAb-A powder that ensures robust stability of the protein in reconstituted solutions intended for subcutaneous injection. This valuable insight has important implications for advancing the development of pharmaceutical formulations with enhanced stability and efficacy.

The Effects of Excipients on Freeze-dried Monoclonal Antibody Formulation Degradation and Sub-Visible Particle Formation during Shaking

PURPOSES

We previously reported an unexpected phenomenon that shaking stress could cause more protein degradation in freeze-dried monoclonal antibody (mAb) formulations than liquid ones (J Pharm Sci, 2022, 2134). The main purposes of the present study were to investigate the effects of shaking stress on protein degradation and sub-visible particle (SbVP) formation in freeze-dried mAb formulations, and to analyze the factors influencing protein degradation during production and transportation.

METHODS

The aggregation behavior of mAb-X formulations during production and transportation was simulated by shaking at a rate of 300 rpm at 25°C for 24 h. The contents of particles and monomers were analyzed by micro-flow imaging, dynamic light scattering, size exclusion chromatography, and ultraviolet - visible (UV-Vis) spectroscopy to compare the protective effects of excipients on the aggregation of mAb-X.

RESULTS

Shaking stress could cause protein degradation in freeze-dried mAb-X formulations, while surfactant, appropriate pH, polyol mannitol, and high protein concentration could impact SbVP generation. Water content had little effect on freeze-dried protein degradation during shaking, as far as the water content was controlled in the acceptable range as recommended by mainstream pharmacopoeias (i.e., less than 3%).

CONCLUSIONS

Shaking stress can reduce the physical stability of freeze-dried mAb formulations, and the addition of surfactants, polyol mannitol, and a high protein concentration have protective effects against the degradation of model mAb formulations induced by shaking stress. The experimental results provide new insight for the development of freeze-dried mAb formulations.

Recombinant therapeutic proteins degradation and overcoming strategies in CHO cells

Mammalian cell lines are frequently used as the preferred host cells for producing recombinant therapeutic proteins (RTPs) having post-translational modified modification similar to those observed in proteins produced by human cells. Nowadays, most RTPs approved for marketing are produced in Chinese hamster ovary (CHO) cells. Recombinant therapeutic antibodies are among the most important and promising RTPs for biomedical applications. One of the issues that occurs during development of RTPs is their degradation, which caused by a variety of factors and reducing quality of RTPs. RTP degradation is especially concerning as they could result in reduced biological functions (antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity) and generate potentially immunogenic species. Therefore, the mechanisms underlying RTP degradation and strategies for avoiding degradation have regained an interest from academia and industry. In this review, we outline recent progress in this field, with a focus on factors that cause degradation during RTP production and the development of strategies for overcoming RTP degradation. KEY POINTS: • The recombinant therapeutic protein degradation in CHO cell systems is reviewed. • Enzymatic factors and non-enzymatic methods influence recombinant therapeutic protein degradation. • Reducing the degradation can improve the quality of recombinant therapeutic proteins.

Optimizing a therapeutic humanized follicle-stimulating hormone-blocking antibody formulation by protein thermal shift assay

Biopharmaceutical products are formulated using several Food and Drug Administration (FDA) approved excipients within the inactive ingredient limit to maintain their storage stability and shelf life. Here, we have screened and optimized different sets of excipient combinations to yield a thermally stable formulation for the humanized follicle-stimulating hormone (FSH)-blocking antibody, MS-Hu6. We used a protein thermal shift assay in which rising temperatures resulted in the maximal unfolding of the protein at the melting temperature (T_m ). To determine the buffer and pH for a stable solution, four different buffers with a pH range from 3 to 8 were screened. This resulted in maximal T_m s at pH 5.62 for Fab in phosphate buffer and at pH 6.85 for Fc in histidine buffer. Upon testing a range of salt concentrations, MS-Hu6 was found to be more stable at lower concentrations, likely due to reduced hydrophobic effects. Molecular dynamics simulations revealed a higher root-mean-square deviation with 1 mM than with 100 mM salt, indicating enhanced stability, as noted experimentally. Among the stabilizers tested, Tween 20 was found to yield the highest T_m and reversed the salt effect. Among several polyols/sugars, trehalose and sucrose were found to produce higher thermal stabilities. Finally, binding of recombinant human FSH to MS-Hu6 in a final formulation (20 mM phosphate buffer, 1 mM NaCl, 0.001% w/v Tween 20, and 260 mM trehalose) resulted in a thermal shift (increase in T_m ) for the Fab, but expectedly not in the Fc domain. Given that we used a low dose of MS-Hu6 (1 μM), the next challenge would be to determine whether 100-fold higher, industry-standard concentrations are equally stable.

Structure-specific amyloid precipitation in biofluids

The composition of soluble toxic protein aggregates formed in vivo is currently unknown in neurodegenerative diseases, due to their ultra-low concentration in human biofluids and their high degree of heterogeneity. Here we report a method to capture amyloid-containing aggregates in human biofluids in an unbiased way, a process we name amyloid precipitation. We use a structure-specific chemical dimer, a Y-shaped, bio-inspired small molecule with two capture groups, for amyloid precipitation to increase affinity. Our capture molecule for amyloid precipitation (CAP-1) consists of a derivative of Pittsburgh Compound B (dimer) to target the cross β-sheets of amyloids and a biotin moiety for surface immobilization. By coupling CAP-1 to magnetic beads, we demonstrate that we can target the amyloid structure of all protein aggregates present in human cerebrospinal fluid, isolate them for analysis and then characterize them using single-molecule fluorescence imaging and mass spectrometry. Amyloid precipitation enables unbiased determination of the molecular composition and structural features of the in vivo aggregates formed in neurodegenerative diseases.

IgG functionalized polymeric nanoparticles for oral insulin administration

The oral route is the best way to administer a drug; however, fitting peptide drugs in this route is a major challenge. In insulin cases, less than 0.5% of the administered dose achieves systemic circulation. Oral delivery by nanoparticles can increase insulin permeability across the intestinal epithelium while maintaining its structure and activity until release in the gut. This system can be improved to increase permeability across intestinal cells through active delivery. This study aimed to improve a nanoparticle formulation by promoting functionalization of its surface with immunoglobulin G to increase its absorption by intestinal epithelium. The characterization of formulations showed an adequate size and a good entrapment efficiency. Functionalized nanoparticles led to a desirable increase in insulin release time. Differential scanning calorimetry, infrared spectroscopy and paper chromatography proved the interactions of nanoparticle components. With immunoglobulin G, the nanoparticle size was slightly increased, which did not show aggregate formation. The developed functionalized nanoparticle formulation proved to be adequate to carry insulin and potentially increase its internalization by epithelial gut cells, being a promising alternative to the existing formulations for orally administered low-absorption peptides.

Effects of polyol excipient stability during storage and use on the quality of biopharmaceutical formulations

Biopharmaceuticals are formulated using a variety of excipients to maintain their storage stability. However, some excipients are prone to degradation during repeated use and/or improper storage, and the impurities generated by their degradation are easily overlooked by end users and are usually not strictly monitored, affecting the stability of biopharmaceuticals. In this study, we evaluated the degradation profile of polyol excipient glycerol during repeated use and improper storage and identified an unprecedented cyclic ketal impurity using gas chromatography with mass spectrometry (GC-MS). The other polyol excipient, mannitol, was much more stable than glycerol. The effects of degraded glycerol and mannitol on the stability of the model biopharmaceutical pentapeptide, thymopentin, were also evaluated. The thymopentin content was only 66.4% in the thymopentin formulations with degraded glycerol, compared to 95.8% in other formulations after the stress test. Most glycerol impurities (i.e., aldehydes and ketones) reacted with thymopentin, affecting the stability of thymopentin formulations. In conclusion, this work suggests that more attention should be paid to the quality changes of excipients during repeated use and storage. Additional testing of excipient stability under real or accelerated conditions by manufacturers would help avoid unexpected and painful results.

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Unprecedented impurities in degraded glycerol were identified with GC-MS.

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Degradation of thymopentin due to glycerol degradation was determined using LC-MS/MS.

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Excipient stability affects biopharmaceutical formulation quality.

Size-based Degradation of Therapeutic Proteins - Mechanisms, Modelling and Control

Protein therapeutics are in great demand due to their effectiveness towards hard-to-treat diseases. Despite their high demand, these bio-therapeutics are very susceptible to degradation via aggregation, fragmentation, oxidation, and reduction, all of which are very likely to affect the quality and efficacy of the product. Mechanisms and modelling of these degradation (aggregation and fragmentation) pathways is critical for gaining a deeper understanding of stability of these products. This review aims to provide a summary of major developments that have occurred towards unravelling the mechanisms of size-based protein degradation (particularly aggregation and fragmentation), modelling of these size-based degradation pathways, and their control. Major caveats that remain in our understanding and control of size-based protein degradation have also been presented and discussed.

Application of a High Throughput and Automated Workflow to Therapeutic Protein Formulation Development

Rapid and efficient formulation development is critical to successfully bringing therapeutic protein drug products into a competitive market under increasingly aggressive timelines. Conventional application of high throughput techniques for formulation development have been limited to lower protein concentrations, which are not applicable to late stage development of high concentration therapeutics. In this work, we present a high throughput (HT) formulation workflow that enables screening at representative concentrations via integration of a micro-buffer exchange system with automated analytical instruments. The operational recommendations associated with the use of such HT systems as well as the efficiencies gained (reduction in hands-on time and run time by over 70% and 30%, respectively), which enable practical characterization of an expanded formulation design space, are discussed. To demonstrate that the workflow is fit for purpose, the formulation properties and stability profiles (SEC and CEX) from samples generated by the HT workflow were compared to those processed by ultrafiltration/diafiltration, and the results were shown to be in good agreement. This approach was further applied to two case studies, one focused on a formulation screen that studied the effects of pH and excipient on viscosity and stability, and the other focused on selection of an appropriate viscosity mimic solution for a protein product.

Stability Studies of the Vaccine Adjuvant U-Omp19

Unlipidated outer membrane protein 19 (U-Omp19) is a novel mucosal adjuvant in preclinical development to be used in vaccine formulations. U-Omp19 holds two main properties, it is capable of inhibiting gastrointestinal and lysosomal peptidases, increasing the amount of co-administered antigen that reaches the immune inductive sites and its half-life inside cells, and it is able to stimulate antigen presenting cells in vivo. These activities enable U-Omp19 to enhance the adaptive immune response to co-administrated antigens.

To characterize the stability of U-Omp19 we have performed an extensive analysis of its physicochemical and biological properties in a 3-year long-term stability study, and under potentially damaging freeze-thawing and lyophilization stress processes. Results revealed that U-Omp19 retains its full protease inhibitor activity, its monomeric state and its secondary structure even when stored in solution for 36 months or after multiple freeze-thawing cycles. Non-enzymatic hydrolysis resulted the major degradation pathway for storage in solution at 4 °C or room temperature which can be abrogated by lyophilization yet increasing protein tendency to form aggregates.

This information will play a key role in the development of a stable formulation of U-Omp19, allowing an extended shelf-life during manufacturing, storage, and shipping of a future vaccine containing this pioneering adjuvant.

Antibody stability: A key to performance - Analysis, influences and improvement

An antibody's stability greatly influences its performance (i.e. its specificity and affinity). Thus, stability is a major issue for researchers and manufacturers, especially with the increasing use of antibodies in therapeutics, diagnostics and rapid analytical platforms. Here we review antibody stability under five headings: (i) measurement techniques; (ii) stability issues in expression and production (expression, proteolysis, aggregation); (iii) effects of antibody format and engineering on stability and (iv) formulation, drying and storage conditions. We consider more than 100 sources, including patents, and conclude with (v) recommendations to promote antibody stability.

Science and art of protein formulation development

Protein pharmaceuticals have become a significant class of marketed drug products and are expected to grow steadily over the next decade. Development of a commercial protein product is, however, a rather complex process. A critical step in this process is formulation development, enabling the final product configuration. A number of challenges still exist in the formulation development process. This review is intended to discuss these challenges, to illustrate the basic formulation development processes, and to compare the options and strategies in practical formulation development.

Exploring the analytical power of the QTOF MS platform to assess monoclonal antibodies quality attributes

The biopharmaceutical industry is growing at a fast pace, making nowadays 20% of the pharma market. Within this market, therapeutic monoclonal antibodies (mAbs) are the dominant product class. With the patent expirations, biosimilars and, perhaps more relevant, biobetters, are in fast development. Thus, a comprehensive characterization at the molecular level of antibodies heterogeneity such as glycoforms, post-translational modifications (PTMs) and sequence variations is of utmost importance. Mass spectrometry (MS)-based approaches are undoubtedly the most powerful analytical strategies to monitor and define an array of critical quality attributes on mAbs. In this work, we demonstrate the analytical power of the Q-TOF MS platform for comprehensive and detailed analysis at molecular levels of an in-house produced mAb. This methodology involves minimal sample preparation procedures and provides an extensive collection of valuable data in a short period of time.

Engineering the hinge region of human IgG1 Fc-fused bispecific antibodies to improve fragmentation resistance

Fc domain fusion can improve the therapeutic effects of relatively small biological molecules such as peptides, cytokines, and antibody fragments. Fc fusion proteins can also be used to enhance the cytotoxic effects of small bispecific antibodies (bsAbs). However, fragmentation of Fc fusion proteins, which mainly occurs around the hinge regions during production, storage, and circulation in the blood, is a major issue. In this study, we first investigated the mechanisms of fragmentation around the hinge region during storage using Fc-fused bsAbs with specificity for epidermal growth factor receptor and CD3 as a model. The fragmentation peaks generated by gel filtration analysis indicated that both contaminating proteases and dissolved active oxygen should be considered causes of fragmentation. We designed and constructed variants by introducing a point mutation into the upper hinge region, which reduced the cleavage caused by dissolved active oxygen, and shortened the hinge region to restrict access of proteases. These hinge modifications improved fragmentation resistance and did not affect the biological activity of the bsAbs in vitro. We confirmed the versatility of the hinge modifications using another Fc-fused bsAb. Our results show that hinge modifications to the Fc fusion protein, especially the introduction of a point mutation into the upper hinge region, can reduce fragmentation substantially, and these modifications can be used to improve the fragmentation resistance of other recombinant Fc fusion proteins.

Kinetics and Characterization of Non-enzymatic Fragmentation of Monoclonal Antibody Therapeutics

PURPOSE

To understand non-enzymatic hydrolytic fragmentation of a monoclonal antibody therapeutic under temperature stressed conditions and investigating possible mechanism for the same.

METHODS

The mAb therapeutic was incubated at 50°C in phosphate buffer at pH 6.5 and fragmentation was monitored at different ionic strengths under stressed conditions. The incubated mAb was sampled at regular time intervals by analytical Size Exclusion Chromatography (SEC).

RESULTS

It was observed that 57% of the mAb product fragmented over 4 days into two fragment species - Fc-Fab and Fab with molecular weights of 97 KDa and 47 KDa, respectively, as measured by mass spectrometry (MS) and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The fragmentation rate was slow initially and then accelerated with time. No change in % aggregate level was observed in this duration, implying that degradation was primarily via fragmentation at high temperature. Kinetics of hydrolytic fragmentation was hypothesized and SEC data was fitted to estimate the kinetic rate constants. While degradation of the monomer into fragment species was non-Arrhenius with a negative activation energy, further degradation of Fab-Fc fragments into Fab or Fc fragments followed Arrhenius Law with an activation energy of 2.1 and 15.38 kcal/mol, respectively.

CONCLUSION

High temperature (50°C) causes mAb to cleave at the hinge region to form Fab-Fc and Fab/Fc, as confirmed by dynamic light scattering, SDS-PAGE, SEC, and MS. A kinetic model for hydrolytic fragmentation has been proposed. The results are expected to assist end users in formulation development as well as in monitoring stability of biotherapeutic products.