Multidimensional Methods for the Formulation of Bipharmaceuticals and Vaccines

Determining and preserving the higher order structural integrity and conformational stability of proteins, plasmid DNA and macromolecular complexes such as viruses, virus-like particles and adjuvanted antigens is often a significant barrier to the successful stabilization and formulation of biopharmaceutical drugs and vaccines. These properties typically must be investigated with multiple lower resolution experimental methods, since each technique monitors only a narrow aspect of the overall conformational state of a macromolecular system. This review describes the use of empirical phase diagrams (EPDs) to combine large amounts of data from multiple high-throughput instruments and construct a map of a target macromolecule's physical state as a function of temperature, solvent conditions, and other stress variables. We present a tutorial on the mathematical methodology, an overview of some of the experimental methods typically used, and examples of some of the previous major formulation applications. We also explore novel applications of EPDs including potential new mathematical approaches as well as possible new biopharmaceutical applications such as analytical comparability, chemical stability, and protein dynamics

Application of analytical characterization tools in process and formulation development of low cost vaccines using the ULTRA manufacturing platform

In 2016, an estimated 19.5 million infants worldwide did not receive routine life-saving vaccinations according to the World Health Organization (WHO)1. Two major limitations in improving global vaccination coverage include the costs associated with vaccine manufacturing and the challenges associated with maintaining a consistent supply. The aim of the ‘ULTRA’ project (Ultra Low-cost TRansferable Automated Platform for Vaccine Manufacturing) is to standardize the development and production of new protein subunit vaccine candidates at globally affordable costs by creating a generic, low-cost, integrated, and automated vaccine manufacturing platform. In a collaborative effort between MIT, UCL, and KU (Figure 1), state-of-the-art analytical tools will be utilized to provide well-characterized vaccine bulk and drug product facilitating process changes and reduced QC costs. Please click Additional Files below to see the full abstract

Formulation development of a stable, orally delivered live human neonatal rotavirus(rv3-bb) vaccine candidate

Rotavirus is the most common cause of gastroenteritis among children under 5 years of age leading to ~200,000 deaths in 2013.1 Rotavirus-attributed mortality can be significantly reduced by promoting global implementation of rotavirus vaccination by vaccine dosage cost reduction and optimizing vaccine efficacy in low-resource countries. Furthermore, a rotavirus vaccine administered at birth could prevent neonatal mortality and reduce the risk of intussusception 2. An oral human neonatal rotavirus vaccine candidate (RV3-BB) has been developed from the human neonatal rotavirus strain RV3 (G3P[6]) 2 , and a recently published Phase IIb clinical trial showed RV3-BB was efficacious in preventing severe rotavirus gastroenteritis via a neonatal or infant schedule in Indonesia2. The overall goals of this project are to develop and implement commercially viable bulk and drug product manufacturing processes of a stable liquid formulation for oral delivery (without pre-neutralization) that is affordable in the developing world (Fig. 1). The consortium working on this program is sponsored by the Bill and Melinda Gates Foundation between Batavia Biosciences, Murdoch Children’s Research Institute, BioFarma, and The University of Kansas. Please click Additional Files below to see the full abstract

Structural Characterization of IgG1 mAb Aggregates and Particles Generated under Various Stress Conditions

IgG1 mAb solutions were prepared with and without sodium chloride and subjected to different environmental stresses. Formation of aggregates and particles of varying size was monitored by a combination of size exclusion chromatography (SEC), Nanosight Tracking Analysis (NTA), Micro-flow Imaging (MFI), turbidity, and visual assessments. Stirring and heating induced the highest concentration of particles. In general, the presence of NaCl enhanced this effect. The morphology of the particles formed from mAb samples exposed to different stresses was analyzed from TEM and MFI images. Shaking samples without NaCl generated the most fibrillar particles, while stirring created largely spherical particles. The composition of the particles was evaluated for covalent cross-linking by SDS-PAGE, overall secondary structure by FTIR microscopy, and surface apolarity by extrinsic fluorescence spectroscopy. Freeze-thaw and shaking led to particles containing protein with native-like secondary structure. Heating and stirring produced IgG1 containing aggregates and particles with some non-native disulfide crosslinks, varying levels of intermolecular beta sheet content, and increased surface hydrophobicity. These results highlight the importance of evaluating protein particle morphology and composition, in addition to particle number and size distributions, to better understand the effect of solution conditions and environmental stresses on the formation of protein particles in mAb solutions

Development of stabilizing formulations of a trivalent inactivated poliovirus vaccine in a dried state for delivery in the Nanopatch™ microprojection array

The worldwide switch to inactivated polio vaccines (IPV) is a key component of the overall strategy to achieve and maintain global polio eradication. To this end, new IPV vaccine delivery systems may enhance patient convenience and compliance. In this work, we examine NanopatchTM (a solid, polymer micro-projection array) which offers potential advantages over standard needle/syringe administration including intradermal delivery and reduced antigen doses. Using trivalent IPV (tIPV) and a purpose-built evaporative dry-down system, candidate tIPV formulations were developed to stabilize tIPV during the drying process and upon storage. Identifying conditions to minimize tIPV potency losses during rehydration and potency testing was a critical first step. Various classes and types of pharmaceutical excipients (~50 total) were then evaluated to mitigate potency losses (measured through D-antigen ELISAs for IPV1, IPV2, and IPV3) during drying and storage. Various concentrations and combinations of stabilizing additives were optimized in terms of tIPV potency retention, and two candidate tIPV formulations containing a cyclodextrin and a reducing agent (e.g., glutathione), maintained ≥80% D-antigen potency during drying and subsequent storage for 4 weeks at 4˚C, and ≥60% potency for 3 weeks at room temperature with the majority of losses occurring within the first day of storage. References: * Wan, Y., et al. (in press), Development of Stabilizing Formulations of a Trivalent Inactivated Poliovirus Vaccine in a Dried State for Delivery in the Nanopatch™ Microprojection Array. Journal of Pharmaceutical Sciences. 2018. Acknowledgements: This work was funded by The World Health Organization

Comparison of the Structural Stability and Dynamic Properties of Recombinant Anthrax Protective Antigen and its 2- Fluorohistidine Labeled Analogue

Protective antigen (PA) is the primary protein antigenic component of both the currently used anthrax vaccine and related recombinant vaccines under development. An analogue of recombinant PA (2-FHis rPA) has been recently shown to block the key steps of pore formation in the process of inducing cytotoxicity in cells, and thus can potentially be used as an antitoxin or a vaccine. This rPA analogue was produced by fermentation to incorporate the unnatural amino acid 2-fluorohistidine (2-FHis). In this study, the effects of 2-FHis labeling on rPA antigen’s conformational stability and dynamic properties were investigated by various biophysical techniques. Temperature/pH stability profiles of rPA and 2-FHis rPA were analyzed by the empirical phase diagram (EPD) approach, and physical stability differences between them were identified. Results showed that rPA and 2-FHis rPA had similar stability at pH 7–8. With decreasing solution pH, however, 2-FHis rPA was found to be more stable. Dynamic sensitive measurements of the two proteins at pH 5 found that 2-FHis rPA was more dynamic and/or differentially hydrated under acidic pH conditions. The biophysical characterization and stability data provide information useful for the potential development of 2-FHis rPA as a more stable rPA vaccine candidate

A C-terminal Pfs48/45 malaria transmission-blocking vaccine candidate produced in the baculovirus expression system

This work is licensed under a Creative Commons Attribution 4.0 International License.The Plasmodium falciparum gametocyte surface protein, Pfs48/45, is a potential target for malaria transmission-blocking vaccines. However, due to its size and complexity, expression of the full-length protein has been difficult, leading to focus on the C-terminal six cysteine domain (6C) with the use of fusion proteins to facilitate expression and folding. In this study, we utilized the baculovirus system to evaluate the expression of three Pfs48/45 proteins including the full-length protein, the 6C domain fragment and the 6C domain mutant to prevent glycosylation. Expression of the recombinant Pfs48/45 proteins was conducted in super Sf9 cells combined with the use of tunicamycin to prevent N-glycosylation. The proteins were then evaluated as immunogens in mice to demonstrate the induction of functionally active polyclonal antibody responses as measured in the standard membrane feeding assay (SMFA). Only the 6C protein was found to exhibit significant transmission-reducing activity. Further characterization of the biologically active 6C protein demonstrated it was homogeneous in terms of size, charge, conformation, absence of glycosylation, and containing proper disulfide bond pairings. This study presents an alternative expression system, without the need of a fusion protein partner, for the Pfs48/45 6C protein fragment including further evaluation as a potential transmission-blocking vaccine candidate

Physical stability comparisons of IgG1-Fc variants: effects of N-glycosylation site occupancy and Asp/Gln residues at site Asn 297

This is the author's accepted manuscript. Made available by the permission of the publisher.The structural integrity and conformational stability of various IgG1-Fc proteins produced from the yeast Pichia pastoris with different glycosylation site occupancy (di-, mono-, and non- glycosylated) was determined. In addition, the physical stability profiles of three different forms of non-glycosylated Fc molecules (varying amino acid residues at site 297 in the CH2 domain due to point mutations and enzymatic digestion of the Fc glycoforms) were also examined. The physical stability of these IgG1-Fc glycoproteins was examined as a function of pH and temperature by high throughput biophysical analysis using multiple techniques combined with data visualization tools (three index empirical phase diagrams and radar charts). Across the pH range of 4.0 to 6.0, the di- and mono- glycosylated forms of the IgG1-Fc showed the highest and lowest levels of physical stability respectively, with the non-glycosylated forms showing intermediate stability depending on solution pH. In the aglycosylated Fc proteins, the introduction of Asp (D) residues at site 297 (QQ vs. DN vs. DD forms) resulted in more subtle changes in structural integrity and physical stability depending on solution pH. The utility of evaluating the conformational stability profile differences between the various IgG1-Fc glycoproteins is discussed in the context of analytical comparability studies

Formulation development of a recombinant protein based non-replicating rotavirus (NRRV) vaccine candidate: Antigen-adjuvant-preservative interactions

Rotavirus is the leading cause of acute diarrhea and gastroenteritis among infants and young children worldwide. Over 215,000 children under five years of age die from rotavirus infection each year, mostly in developing world1. Currently two live attenuated oral rotavirus vaccines are available globally (Rotarix® and RotaTeq®) to reduce the burden of this disease with an efficacy of \u3e90% in developed countries2. Vaccine efficacy is lower, however, in developing countries due to a variety of factors3. To this end, a non-replicating rotavirus (NRRV) vaccine candidate, containing three recombinant protein antigens (P2-VP8-P[4], P2-VP8-P[6] and P2-VP8-P[8]), is being developed by PATH and its partners as a trivalent vaccine for use in the developing world4. This trivalent rotavirus vaccine candidate includes the three antigens from the most prevalent serotypes associated with \u3e90% of rotavirus gastroenteritis worldwide. In the present study, the following formulation development issues were examined: (1) establish stability-indicating physicochemical assays for a NRRV protein antigen (P[8]) bound to an aluminum hydroxide adjuvant (Alhydrogel®), which include primary and higher-order structures, chemical and conformational stability of the protein on Alhydrogel, and the ability to desorb the antigen from Alhydrogel; (2) examine the adsorptive capacity and coefficients of Alhydrogel® for the P[8] antigen in several candidate drug product formulations; (3) investigate the effects of binding to Alhydrogel® and the addition of two antimicrobial preservatives (2-phenoxyethanol or thimerosal) on the structural integrity and conformational stability of P[8], the latter of which were found to be potent destabilizers of the antigen; and (4) monitor the real-time and accelerated storage stability over 3 months of P[8] bound to Alhydrogel® in several candidate formulations with and without thimerosal at different temperatures. In the absence of preservative, the P[8] protein antigen was overall stable with only a small amount of Asn deamidation observed in samples stored under real-time (4˚C) or accelerated (25˚C) temperatures. Similarly, little (if any) changes were observed in the real-time stability of the antigen on Alhydrogel® in the presence of thimerosal. Under accelerated storage temperatures (25 or 37˚C) however, the preservative caused an increase in inter-molecular disulfide bonding, decrease of apparent enthalpy as measured by DSC, and a decrease in in-vitro antigenicity. Similar stability studies are currently ongoing with the P[4] and P[6] protein antigens. Acknowledgements: Funding provided by the Bill & Melinda Gates Foundation References: 1. Tate et al 2016. Clinical Infectious Diseases 62:S96-S105 2. Tissera et al. 2017. Human Vaccines & Immunotherapeutics 13(4):921-927 3. Glass et al. 2014. Journal of Infection 68: S9-S18. 4. Groome et al. 2017. Lancet Infectious Diseases17(8): 843-853

Analytical characterization and formulation assessment of model secretory- immunoglobulin-A (sIgAs) for their potential use as low cost, orally delivered sIgAs

Enterotoxigenic Escherichia coli (ETEC) is a major cause of bacterial diarrheal disease in developing countries, especially among children and infants. ETEC is estimated to cause 280-400 million diarrheal episodes per year in children \u3c5 years of age, resulting in 300,000 to 500,000 deaths.1 Despite the need for a vaccine, there are currently no licensed vaccines against ETEC. Alternatively, passive immunization by oral delivery of pathogen-specific immunoglobulins is another promising approach to provide “instant” protection against ETEC. The potential advantages of oral delivery are reduced cost, simplicity of administration and localized treatment within the GI tract. Secretory IgA (sIgA) is of particular interest because it is naturally found in the mucosal surfaces within the GI tract, relatively more resistant to proteolysis by digestive enzymes (vs. IgGs), and can protect against enteric bacteria by directly neutralizing virulence factors.2 One major challenge of this approach is the instability of protein molecules during oral delivery (in the digestive tract) as well as during long-term storage (in various formulations). In this study, two proteins, sIgA1 and sIgA2 against heat labile toxin (LT, one of the major virulence factors of ETEC), were used as model sIgA molecules for developing analytical techniques and assessing stability (physicochemical as well as in vitro binding) under various conditions. A combination of biochemical and biophysical methods were employed to comprehensively characterize the sIgA1 and sIgA2 model proteins including primary structure, post translational modifications (i.e., N-linked glycans), size, apparent solubility, higher order structure and conformational stability as well as in vitro antigen binding. Using these characterization and stability indicating methods, we are monitoring the stability of these two model sIgAs both in an in vitro digestion model (to mimic in vivo degradation conditions), and during accelerated stability studies (to assess storage stability). Our goal is to use the information gained by these aforementioned methods and stability studies to design stable, low-cost liquid formulations for oral delivery of sIgAs in the developing world. Please click Additional Files below to see the full abstract