Advanced Formulation Approaches for Proteins

Proteins and peptides are highly desirable as therapeutic agents, being highly potent and specific. However, there are myriad challenges with processing them into patient-friendly formulations: they are often unstable and have a tendency to aggregate or degrade upon storage. As a result, the vast majority of protein actives are delivered parenterally as solutions, which has a number of disadvantages in terms of cost, accessibility, and patient experience. Much work has been undertaken to develop new delivery systems for biologics, but to date this has led to relatively few products on the market. In this chapter, we review the challenges faced when developing biologic formulations, discuss the technologies that have been explored to try to overcome these, and consider the different delivery routes that can be applied. We further present an overview of the currently marketed products and assess the likely direction of travel in the next decade.

Injectable hydrogel particles for amorphous solid formulation of biologics

The fast pace of breakthroughs in cancer immunotherapy, combined with the new paradigm of moving toward high-concentration dosages and combinatorial treatments, is generating new challenges in the formulation of biologics. To address these challenges, we describe a method of formulation that enables high-concentration injectable and stable formulation of biologics as amorphous solids in aqueous suspension. This technology combines the benefits of liquid formulation with the stability of solid formulation and eliminates the need for drying and reconstitution. This widely applicable formulation integrates the amorphous solid forms of antibodies with the injectability, lubricity, and tunability of soft alginate hydrogel particles using a minimal process. The platform was evaluated for anti-PD-1 antibody pembrolizumab and human immunoglobulin G at concentrations up to 300 mg/mL with confirmed quality after release. The soft nature of the hydrogel matrix allowed packing the particles to high volume fractions.

Impact of Post-Freeze Annealing on Shrinkage of Sucrose and Trehalose Lyophilisates

Freeze-drying of pharmaceuticals produces lyophilisates with properties that depend on both the formulation and the process. Characterisation of the lyophilisate in terms of appearance is necessary not only to produce a visually appealing product, but also to gain insight into the freeze-drying process. The present study investigates the impact of post-freeze annealing on the volume of lyophilisates. For this purpose, sucrose and trehalose solutions were freeze-dried with different annealing conditions and the resulting lyophilisates were analysed with a 3D structured light scanner. The external structure of the lyophilisates was found to be dependent on the bulk materials as well as the choice of vials, while the volume was influenced by the annealing time and temperature. Additionally, differential scanning calorimetry was used to determine glass transition temperatures of frozen samples. As a novelty, the volumes of the lyophilisates and their corresponding glass transition temperatures were compared. This resulted in a correlation supporting the theory that the shrinkage of lyophilisates depends on the amount of residual water in the freeze-concentrated amorphous phase before drying. Understanding the volume change of lyophilisates, in combination with material properties such as glass transition temperature, forms the basis for relating physicochemical properties to process parameters in lyophilisation.

A Platform Approach to Protein Encapsulates with Controllable Surface Chemistry

The encapsulation of proteins into core-shell structures is a widely utilised strategy for controlling protein stability, delivery and release. Despite the recognised utility of these microstructures, however, core-shell fabrication routes are often too costly or poorly scalable to allow for industrial translation. Furthermore, many scalable routes rely upon emulsion-techniques implicating denaturing or environmentally harmful organic solvents. Herein, we investigate core-shell protein encapsulation through single-feed, aqueous spray drying: a cheap, industrially ubiquitous particle-formation technology in the absence of organic solvents. We show that an excipient’s preference for the surface of the spray dried particle is well-predicted by its hydrodynamic diameter (Dh) under relevant feed buffer conditions (pH and ionic strength) and that the predictive power of Dh is improved when measured at the spray dryer outlet temperature compared to room temperature (R2 = 0.64 vs. 0.59). Lastly, we leverage these findings to propose an adaptable design framework for fabricating core-shell protein encapsulates by single-feed aqueous spray drying.

Synergistic antimicrobial interactions of nisin A with biopolymers and solubilising agents for oral drug delivery

In order to develop bacteriocins, like the lantibiotic nisin A, into effective alternatives to existing antibiotics, their biophysical and physicochemical properties must first be assessed, from solubility, to susceptibility and absorption. It has been well established that formulation strategies at early drug development stages can be crucial for successful outcomes during preclinical and clinical phases of development, particularly for molecules with challenging physicochemical properties. This work elucidates the physicochemical challenges of nisin A in terms of its susceptibility to digestive enzymes like pepsin, pancreatin and proteinase K and its poor solubility at physiological pHs. Low solution concentrations, below the minimum inhibitory concentration against Staphylococcus aureus, were obtained in phosphate buffered saline (PBS, pH 7.4) and in fasted state simulated intestinal fluid (FaSSIF, pH 6.5), while higher solubilities at more acidic pH's such as in a KCl/HCl buffer (pH 2) and in fasted state simulated gastric fluid (FaSSGF, pH 1.6) are observed. Tween® 80 (0.01% v/v) significantly increased the solution concentration of nisin A in PBS (pH 7.4, 24 hr). Pancreatin doubled nisin A's solution concentration at pH 7.4 (PBS) but reduced its' inhibitory activity to ∼ 20%, and pepsin almost completely degraded nisin (after 24 hr), but retained activity at biologically relevant exposure times (∼ 15 min). Harnessing synergism between nisin A and either glycol chitosan or ε-poly lysine, combined with the solubilizing effect of Tween®, increased the antimicrobial activity of nisin A six fold in an in vitro oral administration model.

Increasing robustness, reliability and storage stability of critical reagents by freeze-drying

Aim: Stabilization of critical reagents by freeze-drying would facilitate storage and transportation at ambient temperatures, and simultaneously enable constant reagent performance for long-term bioanalytical support throughout drug development. Freeze-drying as a generic process for stable performance and storage of critical reagents was investigated by establishing an universal formulation buffer and lyophilization process. Results: Using a storage-labile model protein, formulation buffers were evaluated to preserve reagent integrity during the freeze-drying process, and to retain functional performance after temperature stress. Application to critical reagents used in pharmacokinetics and anti-drug antibodies assays demonstrated stable functional performance of the reagents after 11 month at +40°C. Conclusion: Stabilization and storage of critical assay reagents by freeze-drying is an attractive alternative to traditional deep freezing.

Development of mAb-loaded 3D-printed (FDM) implantable devices based on PLGA

The main objective of this work was to explore the feasibility to print monoclonal antibody (mAb)-loaded implantable systems using fused-deposition modelling (FDM) to build complex dosage form designs. Indeed, to our knowledge, this work is the first investigation of mAb-loaded devices using FDM. To make this possible, different steps were developed and optimized. A mAb solution was stabilized using trehalose (TRE), sucrose (SUC), hydroxypropyl-β-cyclodextrin (HP-β-CD), sorbitol or inulin (INU) in order to be spray dried (SD). Printable filaments were then made of poly(lactide-co-glycolide) (PLGA) and mAb powder (15% w/w) using hot melt extrusion (HME). The FDM process was optimized to print these filaments without altering the mAb stability. TRE was selected and associated to L-leucine (LEU) to increase the mAb stability. The stability was then evaluated considering high and low molecular weight species levels. The mAb-based devices were well-stabilized with the selected excipients during both the HME and the FDM processes. The 3D-printed devices showed sustained-release profiles with a low burst effect. The mAb-binding capacity was preserved up to 70% following the whole fabrication process. These promising results demonstrate that FDM could be used to produce mAb-loaded devices with good stability, affinity and sustained-release profiles of the mAb.

Monoclonal antibody formulation manufactured by high-speed electrospinning

Solid formulations of monoclonal antibodies present several advantages, such as improved stability and increased shelf-life as well as simpler storage and transportation. In this study, we present a gentle drying technology for monoclonal antibodies, applying the water soluble 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) as matrix, to prepare a solid reconstitution dosage form. High-speed electrospinning of an aqueous infliximab-containing HP-β-CD solution was carried out at 25 °C resulting in fibers with an average diameter of 2.5 μm. The mAb-loaded electrospun fibers were successful to preserve the stability of infliximab in solid form. The results of size exclusion chromatography and gel electrophoresis indicated no significant increase in aggregate formation during the electrospinning process compared to the initial matrix solution. The binding activity of infliximab was preserved during electrospinning compared to the reference liquid formulation. Due to the enhanced surface area, excellent reconstitution capability, i.e. clear solution within 2 min without any vigorous mixing, could be achieved in a small-scale reconstitution test. The results of this work demonstrate that high-speed electrospinning is a very promising technique to manufacture the solid formulation of monoclonal antibodies for applications such as fast reconstitutable powders.

Protein encapsulation by electrospinning and electrospraying

Given the increasing interest in the use of peptide- and protein-based agents in therapeutic strategies, it is fundamental to develop delivery systems capable of preserving the biological activity of these molecules upon administration, and which can provide tuneable release profiles. Electrohydrodynamic (EHD) techniques, encompassing electrospinning and electrospraying, allow the generation of fibres and particles with high surface area-to-volume ratios, versatile architectures, and highly controllable release profiles. This review is focused on exploring the potential of different EHD methods (including blend, emulsion, and co-/multi-axial electrospinning and electrospraying) for the development of peptide and protein delivery systems. An overview of the principles of each technique is first presented, followed by a survey of the literature on the encapsulation of enzymes, growth factors, antibodies, hormones, and vaccine antigens using EHD approaches. The possibility for localised delivery using stimuli-responsive systems is also explored. Finally, the advantages and challenges with each EHD method are summarised, and the necessary steps for clinical translation and scaled-up production of electrospun and electrosprayed protein delivery systems are discussed.

Williams G, Brocchini S, Awwad S. Injectables and Depots to Prolong Drug Action of Proteins and Peptides

Proteins and peptides have emerged in recent years to treat a wide range of multifaceted diseases such as cancer, diabetes and inflammation. The emergence of polypeptides has yielded advancements in the fields of biopharmaceutical production and formulation. Polypeptides often display poor pharmacokinetics, limited permeability across biological barriers, suboptimal biodistribution, and some proclivity for immunogenicity. Frequent administration of polypeptides is generally required to maintain adequate therapeutic levels, which can limit efficacy and compliance while increasing adverse reactions. Many strategies to increase the duration of action of therapeutic polypeptides have been described with many clinical products having been developed. This review describes approaches to optimise polypeptide delivery organised by the commonly used routes of administration. Future innovations in formulation may hold the key to the continued successful development of proteins and peptides with optimal clinical properties.

Scaled-Up Production and Tableting of Grindable Electrospun Fibers Containing a Protein-Type Drug

The aims of this work were to develop a processable, electrospun formulation of a model biopharmaceutical drug, β-galactosidase, and to demonstrate that higher production rates of biopharmaceutical-containing fibers can be achieved by using high-speed electrospinning compared to traditional electrospinning techniques. An aqueous solution of 7.6 w/w% polyvinyl alcohol, 0.6 w/w% polyethylene oxide, 9.9 w/w% mannitol, and 5.4 w/w% β-galactosidase was successfully electrospun with a 30 mL/h feeding rate, which is about 30 times higher than the feeding rate usually attained with single-needle electrospinning. According to X-ray diffraction measurements, polyvinyl alcohol, polyethylene oxide, and β-galactosidase were in an amorphous state in the fibers, whereas mannitol was crystalline (δ-polymorph). The presence of crystalline mannitol and the low water content enabled appropriate grinding of the fibrous sample without secondary drying. The ground powder was mixed with excipients commonly used during the preparation of pharmaceutical tablets and was successfully compressed into tablets. β-galactosidase remained stable during each of the processing steps (electrospinning, grinding, and tableting) and after one year of storage at room temperature in the tablets. The obtained results demonstrate that high-speed electrospinning is a viable alternative to traditional biopharmaceutical drying methods, especially for heat sensitive molecules, and tablet formulation is achievable from the electrospun material prepared this way.

Drying technology strategies for colon-targeted oral delivery of biopharmaceuticals

In chronic intestinal diseases like inflammatory bowel disease, parenteral administration of biopharmaceuticals is associated with numerous disadvantages including immune reactions, infections, low patient compliance, and toxicity caused by high systemic bioavailability. One alternative that can potentially overcome these limitations is oral administration of biopharmaceuticals, where the local delivery will reduce the systemic exposure and furthermore the manufacturing costs will be lower. However, the development of oral dosage forms that deliver the biologically active form to the intestines is one of the greatest challenges for pharmaceutical technologists due to the sensitive nature of biopharmaceuticals. The present article discusses the various drug delivery technologies used to produce orally administered solid dosage forms of biopharmaceuticals with an emphasis on colon-targeted delivery. Solid oral dosage compositions containing different types of colon-targeting biopharmaceuticals are compiled followed by a review of currently applied and emerging drying technologies for biopharmaceuticals. The different drying technologies are compared in terms of their advantages, limitations, costs and their effect on product stability.

Peculiarities of Protein Crystal Nucleation and Growth

This paper reviews investigations on protein crystallization. It aims to present a comprehensive rather than complete account of recent studies and efforts to elucidate the most intimate mechanisms of protein crystal nucleation. It is emphasized that both physical and biochemical factors are at play during this process. Recently-discovered molecular scale pathways for protein crystal nucleation are considered first. The bond selection during protein crystal lattice formation, which is a typical biochemically-conditioned peculiarity of the crystallization process, is revisited. Novel approaches allow us to quantitatively describe some protein crystallization cases. Additional light is shed on the protein crystal nucleation in pores and crevices by employing the so-called EBDE method (equilibration between crystal bond and destructive energies). Also, protein crystal nucleation in solution flow is considered.

Parenteral protein formulations: An overview of approved products within the European Union

The study presented is a comprehensive overview of commercial parenteral protein formulations, approved by the European Medicines Agency (EMA), 1995-2018. The objective of this overview was to analyse current trends in the design of commercial parenteral protein products and thereby support formulation scientists in the design of new formulations. The main data source was the publicly available European Public Assessment Reports (EPARs) published by the EMA for each authorised product. An analysis of the percentage of formulations in a liquid and lyophilised form was conducted. In addition, the number of products containing individual excipients, classified into functional categories is provided. Finally, the overview includes comprehensive details of product compositions obtained from EMA, US Food and Drug Administration (FDA) and product Marketing Authorisation Holder. Data analysis highlighted trends in the number of products approved, and the higher percentage of liquid parenteral protein formulations (66%) compared to lyophilised formulations (34%). This overview identifies the most commonly incorporated excipients employed as buffering agents, stabilisers/bulking agents, surfactants, preservatives and tonicifiers, including their concentration ranges of use in both liquid and lyophilised formulation approaches. Finally, antibody-based formulations were a particular focus of this overview. The relationship between parenteral routes of administration and antibody concentrations in approved products was also investigated.

Overview of Antibody Drug Delivery

Monoclonal antibodies (mAbs) are one of the most important classes of therapeutic proteins, which are used to treat a wide number of diseases (e.g., oncology, inflammation and autoimmune diseases). Monoclonal antibody technologies are continuing to evolve to develop medicines with increasingly improved safety profiles, with the identification of new drug targets being one key barrier for new antibody development. There are many opportunities for developing antibody formulations for better patient compliance, cost savings and lifecycle management, e.g., subcutaneous formulations. However, mAb-based medicines also have limitations that impact their clinical use; the most prominent challenges are their short pharmacokinetic properties and stability issues during manufacturing, transport and storage that can lead to aggregation and protein denaturation. The development of long acting protein formulations must maintain protein stability and be able to deliver a large enough dose over a prolonged period. Many strategies are being pursued to improve the formulation and dosage forms of antibodies to improve efficacy and to increase the range of applications for the clinical use of mAbs.

Development of a drug delivery system for efficient alveolar delivery of a neutralizing monoclonal antibody to treat pulmonary intoxication to ricin

The high toxicity of ricin and its ease of production have made it a major bioterrorism threat worldwide. There is however no efficient and approved treatment for poisoning by ricin inhalation, although there have been major improvements in diagnosis and therapeutic strategies. We describe the development of an anti-ricin neutralizing monoclonal antibody (IgG 43RCA-G1) and a device for its rapid and effective delivery into the lungs for an application in humans. The antibody is a full-length IgG and binds to the ricin A-chain subunit with a high affinity (KD=53pM). Local administration of the antibody into the respiratory tract of mice 6h after pulmonary ricin intoxication allowed the rescue of 100% of intoxicated animals. Specific operational constraints and aerosolization stresses, resulting in protein aggregation and loss of activity, were overcome by formulating the drug as a dry-powder that is solubilized extemporaneously in a stabilizing solution to be nebulized. Inhalation studies in mice showed that this formulation of IgG 43RCA-G1 did not induce pulmonary inflammation. A mesh nebulizer was customized to improve IgG 43RCA-G1 deposition into the alveolar region of human lungs, where ricin aerosol particles mostly accumulate. The drug delivery system also comprises a semi-automatic reconstitution system to facilitate its use and a specific holding chamber to maximize aerosol delivery deep into the lung. In vivo studies in monkeys showed that drug delivery with the device resulted in a high concentration of IgG 43RCA-G1 in the airways for at least 6h after local deposition, which is consistent with the therapeutic window and limited passage into the bloodstream.

In situ Endothelialization: Bioengineering Considerations to Translation

Improving patency rates of current cardiovascular implants remains a major challenge. It is widely accepted that regeneration of a healthy endothelium layer on biomaterials could yield the perfect blood-contacting surface. Earlier efforts in pre-seeding endothelial cells in vitro demonstrated success in enhancing patency, but translation to the clinic is largely hampered due to its impracticality. In situ endothelialization, which aims to create biomaterial surfaces capable of self-endothelializing upon implantation, appears to be an extremely promising solution, particularly with the utilization of endothelial progenitor cells (EPCs). Nevertheless, controlling cell behavior in situ using immobilized biomolecules or physical patterning can be complex, thus warranting careful consideration. This review aims to provide valuable insight into the rationale and recent developments in biomaterial strategies to enhance in situ endothelialization. In particular, a discussion on the important bio-/nanoengineering considerations and lessons learnt from clinical trials are presented to aid the future translation of this exciting paradigm.