Improvement of Certolizumab Fab' properties by PASylation technology

Biosensing-based quality control monitoring of the higher-order structures of therapeutic antibody domains

Advanced biopharmaceutical manufacturing requires novel process analytical technologies for the rapid and sensitive assessment of the higher-order structures of therapeutic proteins. However, conventional physicochemical analyses of denatured proteins have limitations in terms of sensitivity, throughput, analytical resolution, and real-time monitoring capacity. Although probe-based sensing can overcome these limitations, typical non-specific probes lack analytical resolution and provide little to no information regarding which parts of the protein structure have been collapsed. To meet these analytical demands, we generated biosensing probes derived from artificial proteins that could specifically recognize the higher-order structural changes in antibodies at the protein domain level. Biopanning of phage-displayed protein libraries generated artificial proteins that bound to a denatured antibody domain, but not its natively folded structure, with nanomolar affinity. The protein probes not only recognized the higher-order structural changes in intact IgGs but also distinguished between the denatured antibody domains. These domain-specific probes were used to generate response contour plots to visualize the antibody denaturation caused by various process parameters, such as pH, temperature, and holding time for acid elution and virus inactivation. These protein probes can be combined with established analytical techniques, such as surface plasmon resonance for real-time monitoring or plate-based assays for high-throughput analysis, to aid in the development of new analytical technologies for the process optimization and monitoring of antibody manufacturing.

Long-Acting Strategies for Antibody Drugs: Structural Modification, Controlling Release, and Changing the Administration Route

Because of their high specificity, high affinity, and targeting, antibody drugs have been widely used in the treatment of many diseases and have become the most favored new drugs for research in the world. However, some antibody drugs (such as small-molecule antibody fragments) have a short half-life and need to be administered frequently, and are often associated with injection-site reactions and local toxicities during use. Increasing attention has been paid to the development of antibody drugs that are long-acting and have fewer side effects. This paper reviews existing strategies to achieve long-acting antibody drugs, including modification of the drug structure, the application of drug delivery systems, and changing their administration route. Among these, microspheres have been studied extensively regarding their excellent tolerance at the injection site, controllable loading and release of drugs, and good material safety. Subcutaneous injection is favored by most patients because it can be quickly self-administered. Subcutaneous injection of microspheres is expected to become the focus of developing long-lasting antibody drug strategies in the near future.

Expression, Purification, and Biological Evaluation of XTEN-GCSF in a Neutropenic Rat Model

Granulocyte colony-stimulating factor (GCSF) stimulates the proliferation of neutrophils but it has low serum half-life. Therefore, the present study was done to investigate the effect of XTENylation on biological activity, pharmacokinetics, and pharmacodynamics of GCSF in a neutropenic rat model. XTEN tag was genetically fused to the N-terminal region of GCSF-encoding gene fragment and subcloned into pET28a expression vector. The cytoplasmic expressed recombinant protein was characterized through intrinsic fluorescence spectroscopy (IFS), dynamic light scattering (DLS), and size exclusion chromatography (SEC). In vitro biological activity of the XTEN-GCSF protein was evaluated on NFS60 cell line. Hematopoietic properties and pharmacokinetics were also investigated in a neutropenic rat model. An approximately 140 kDa recombinant protein was detected on SDS-PAGE. Dynamic light scattering and size exclusion chromatography confirmed the increase in hydrodynamic diameter of GCSF molecule after XTENylation. GCSF derivatives showed efficacy in proliferation of NFS60 cell line among which the XTEN-GCSF represented the lowest EC50 value (100.6 pg/ml). Pharmacokinetic studies on neutropenic rats revealed that XTEN polymer could significantly increase protein serum half-life in comparison with the commercially available GCSF molecules. PEGylated and XTENylated GCSF proteins were more effective in stimulation of neutrophils compared to the GCSF molecule alone. XTENylation of GCSF represented promising results in in vitro and in vivo studies. This approach can be a potential alternative to PEGylation strategies for increasing serum half-life of protein.

Polypeptides as alternatives to PEGylation of therapeutic agents

INTRODUCTION

Due to the concerns raised by the extensive application of PEGylation, polypeptides have stood out as excellent candidates with adequate biocompatibility and biodegradability with tunable hydrophilicity.

AREAS COVERED

In this review, polypeptides with the potential to replace PEGylation have been summarized and their application has been reviewed, including XTEN, PASylation, polysarcosine, zwitterion polypeptides, ELPylation, etc. Besides their strengths, the remaining challenges have also been discussed and the future perspectives have been provided.

EXPERT OPINION

Polypeptides have been applied in the designing of peptide/protein drugs as well as nanomedicines, and some of the pharmaceutics have made it into the clinical trials and got approved. These polypeptides showed similar hydrophilic properties to PEGylation, which increased the hydrodynamic volumes of protein drugs, reduced kidney elimination, decreased protein-polymer interaction and potentially improved the drug delivery efficiency due to the extended circulation time in the system. Moreover, they demonstrated superior biodegradability and biocompatibility, compensating for the deficiencies for polymers such as PEG.

Production of bioactive recombinant monoclonal antibody fragment in periplasm of Escherichia coli expression system

The microbial expression system (Escherichia coli) is the most widely studied host for the production of biotherapeutic products, such as antibody fragments, single chain variable fragments and nanobodies. However, recombinant biotherapeutic proteins are often expressed as insoluble proteins, thereby limiting the utility of E. coli as expression system. To overcome this limitation, various strategies have been developed, such as changes at DNA level (codon optimization), fusion with soluble tags and variations in process parameters (temperature), and inducer concentration. However, there is no "one size fits all" strategy. The most commonly used approach involves induction at low temperature, as reducing the temperature during cultivation has been reported to increase bioactive protein production in E. coli. In this study, we examine the impact of various process parameters, such as temperature and inducer concentration, as well as, high plasmid copy number vector for achieving enhanced soluble expression of TNFα inhibitor Fab. An interaction amongst these parameters has been observed and their optimization has been demonstrated to result in expression of 30 ± 3 mg/L antibody fragment using E. coli. This case study illustrates how process optimization can contribute toward making biotherapeutics affordable.

Unstructured Polypeptides as a Versatile Drug Delivery Technology

Although polyethylene glycol (PEG), or "PEGylation" has become a widely applied approach for improving the efficiency of drug delivery, the immunogenicity and non-biodegradability of this synthetic polymer have prompted an evident need for alternatives. To overcome these caveats and to mimic PEG -or other natural or synthetic polymers- for the purpose of drug half-life extension, unstructured polypeptides are designed. Due to their tunable length, biodegradability, low immunogenicity and easy production, unstructured polypeptides have the potential to replace PEG as the preferred technology for therapeutic protein/peptide delivery. This review provides an overview of the evolution of unstructured polypeptides, starting from natural polypeptides to engineered polypeptides and discusses their characteristics. Then, it is described that unstructured polypeptides have been successfully applied to numerous drugs, including peptides, proteins, antibody fragments, and nanocarriers, for half-life extension. Innovative applications of unstructured peptides as releasable masks, multimolecular adaptors and intracellular delivery carriers are also discussed. Finally, challenges and future perspectives of this promising field are briefly presented. STATEMENT OF SIGNIFICANCE: : Polypeptide fusion technology simulating PEGylation has become an important topic for the development of long-circulating peptide or protein drugs without reduced activity, complex processes, and kidney injury caused by PEG modification. Here we provide a detailed and in-depth review of the recent advances in unstructured polypeptides. In addition to the application of enhanced pharmacokinetic performance, emphasis is placed on polypeptides as scaffolders for the delivery of multiple drugs, and on the preparation of reasonably designed polypeptides to manipulate the performance of proteins and peptides. This review will provide insight into future application of polypeptides in peptide or protein drug development and the design of novel functional polypeptides.

A Review of Protein- and Peptide-Based Chemical Conjugates: Past, Present, and Future

Over the past few decades, the complexity of molecular entities being advanced for therapeutic purposes has continued to evolve. A main propellent fueling innovation is the perpetual mandate within the pharmaceutical industry to meet the needs of novel disease areas and/or delivery challenges. As new mechanisms of action are uncovered, and as our understanding of existing mechanisms grows, the properties that are required and/or leveraged to enable therapeutic development continue to expand. One rapidly evolving area of interest is that of chemically enhanced peptide and protein therapeutics. While a variety of conjugate molecules such as antibody-drug conjugates, peptide/protein-PEG conjugates, and protein conjugate vaccines are already well established, others, such as antibody-oligonucleotide conjugates and peptide/protein conjugates using non-PEG polymers, are newer to clinical development. This review will evaluate the current development landscape of protein-based chemical conjugates with special attention to considerations such as modulation of pharmacokinetics, safety/tolerability, and entry into difficult to access targets, as well as bioavailability. Furthermore, for the purpose of this review, the types of molecules discussed are divided into two categories: (1) therapeutics that are enhanced by protein or peptide bioconjugation, and (2) protein and peptide therapeutics that require chemical modifications. Overall, the breadth of novel peptide- or protein-based therapeutics moving through the pipeline each year supports a path forward for the pursuit of even more complex therapeutic strategies.

PASylated Urate Oxidase Enzyme: Enhancing Biocatalytic Activity, Physicochemical Properties, and Plasma Half-Life

Recombinant urate oxidase (UOX, E.C.1.7.3.3) is an important therapeutic enzyme used in preventing and treating chemotherapy-induced hyperuricemia and severe gout. However, UOX use is limited due to the poor stability and short plasma half-life. To solve this problem, we designed three PASylated variants of Aspergillus flavus UOX with different PAS sequences at the C- or N-terminus. The genes of native and PASylated variants (UOX-PAS₂₀, PAS₂₄-UOX, and UOX-PAS₁₀₀) were designed and produced in Escherichia coli strain BL21 (DE3). The expressed recombinant native and PASylated enzymes were compared in terms of biophysical properties, kinetics parameters, and pharmacokinetics behavior using standard methods. PASylation of UOX with PAS₁₀₀ polymer caused a 1.24-fold reduction in K _m to 52.61 μM, and a 3.87-fold increase in K _cat/K _m for uric acid compared to the native variant. UOX-PAS₁₀₀ retained its activity in different temperatures (20-55 °C); however, other variants lost nearly 50% of their original activity at 55 °C. UOX-PAS₁₀₀ exhibited a 1.78-fold increase in hydrodynamic radius and a 1.64-fold larger apparent molecular size in comparison to the native UOX. Circular dichroism (CD) spectroscopy demonstrated that the addition of the PAS tag does not change the secondary structure of the fusion enzyme. The tryptophan fluorescence emission spectra for PASylated enzymes showed a significant modification in the conformational state of UOX by the PAS polymer presence. UOX-PAS₁₀₀ retained 89.0% of the original activity following 72 h incubation in the presence of plasma at 37 °C. However, only about 61.0%, 57.0%, 50.0%, and 52.0% of activity from PAS₂₄-UOX, UOX-PAS₂₀, native UOX, and rasburicase (Fasturtec, Italy) remained, respectively, at the identical time. UOX-PAS₁₀₀ had an increased biological half-life (8.21 h) when compared with the rasburicase (3.12 h) and native UOX (2.87 h) after being injected into a rat. Having considering everything, our results suggest that the UOX-PAS₁₀₀, an A. flavus UOX fused with a C-terminally 100 amino acid PAS-residue, is a proper candidate with enhanced biological activity and extended plasma half-life for clinical therapy in patients suffering from hyperuricemia.

Recombinant protein polymer-antibody conjugates for applications in nanotechnology and biomedicine

Currently, there are over 100 antibody-based therapeutics on the market for the treatment of various diseases. The increasing importance of antibody treatment is further highlighted by the recent FDA emergency use authorization of certain antibody therapies for COVID-19 treatment. Protein-based materials have gained momentum for antibody delivery due to their biocompatibility, tunable chemistry, monodispersity, and straightforward synthesis and purification. In this review, we discuss progress in engineering the molecular features of protein-based biomaterials, in particular recombinant protein polymers, for introducing novel functionalities and enhancing the delivery properties of antibodies and related binding protein domains.

Identification of a novel fully human anti-toxic shock syndrome toxin (TSST)-1 single-chain variable fragment antibody averting TSST-1-induced mitogenesis and cytokine secretion

Background

Staphylococcal superantigens are virulence factors that help the pathogen escape the immune system and develop an infection. Toxic shock syndrome toxin (TSST)-1 is one of the most studied superantigens whose role in toxic shock syndrome and some particular disorders have been demonstrated. Inhibiting TSST-1 production with antibiotics and targeting TSST-1 with monoclonal antibodies might be one of the best strategies to prevent TSST-1-induced cytokines storm followed by lethality.

Results

A novel single-chain variable fragment (scFv), MS473, against TSST-1 was identified by selecting an scFv phage library on the TSST-1 protein. The MS473 scFv showed high affinity and specificity for TSST-1. Moreover, MS473 could significantly prevent TSST-1-induced mitogenicity (the IC₅₀ value: 1.5 µM) and cytokine production.

Conclusion

Using traditional antibiotics with an anti-TSST-1 scFv as a safe and effective agent leads to deleting the infection source and preventing the detrimental effects of the toxin disseminated into the whole body.

Supplementary information

The online version contains supplementary material available at 10.1186/s12896-022-00760-8.

Identification of two neutralizing human single-chain variable fragment antibodies targeting Staphylococcus aureus alpha-hemolysin

OBJECTIVES

The inability of the host immune system to defeat Staphylococcus aureus is due to various secreted virulent factors such as leukocidins, superantigens, and hemolysins, which interrupt the function of immune components. Alpha-hemolysin is one of the most studied cytolysins due to its pronounced effect on developing staphylococcal infections. Alpha-hemolysin-neutralizing antibodies are among the best candidates for blocking the toxin activity and preventing S. aureus pathogenesis.

MATERIALS AND METHODS

A human single-chain variable fragment (scFv) phage display library was biopanned against alpha-hemolysin. The selected phage clones were assessed based on their binding ability to alpha-hemolysin. The binding specificity and affinity of two scFvs (designated SP192 and SP220) to alpha-hemolysin were determined by enzyme-linked immunosorbent assay. Furthermore, the neutralizing activity of SP192 and SP220 was examined by concurrent incubation of rabbit red blood cells (RBCs) with alpha-hemolysin and scFvs.

RESULTS

SP192 and SP220 showed significant binding to alpha-hemolysin compared with the control proteins, including bovine serum albumin, human adiponectin, and toxic shock syndrome toxin-1. Besides, both scFvs showed high-affinity binding to alpha-hemolysin in the nanomolar range (Kaff: 0.9 and 0.7 nM^-1, respectively), leading to marked inhibition of alpha-hemolysin-mediated lysis of rabbit RBCs (73% and 84% inhibition; respectively).

CONCLUSION

SP192 and SP220 scFvs can potentially be used as alpha-hemolysin-neutralizing agents in conjunction with conventional antibiotics to combat S. aureus infections.

Production of Soluble and Functional Anti-TNF-α Fab' Fragment in Cytoplasm of E. coli: Investigating the Effect of Process Conditions on Cellular Biomass and Protein Yield Using Response Surface Methodology

With the increasing dominance of monoclonal antibodies (mAbs) in the biopharmaceutical industry and smaller antibody fragments bringing notable advantages over full-length antibodies, it is of considerable significance to choose the most suitable production system. Although mammalian expression system has been the preferred choice in recent years for mAbs production, E. coli could be the favorable host for non-glycosylated small antibody fragments due to the emergence of new engineered E. coli strains capable of forming disulfide-bonds in their cytoplasm.In this study, non-glycosylated anti-TNF-α Fab' moiety of Certolizumab pegol, produced by periplasmic expression in E. coli in previous studies, was produced in the cytoplasm of E. coli SHuffle strain. The results indicated that it is biologically functional by testing the antigen-binding activity via indirect ELISA and inhibition of TNF-α induced cytotoxicity using MTT test. Major factors affecting protein production and, optimized culture conditions were examined by analyzing growth characteristics and patterns of expression in 24 h of post-induction cultivation and, optimization of culture conditions by response surface methodology considering temperature, time of induction and concentration of inducer in small (tube) and shake-flask scale. Based on the results, temperature had the most significant influence on functional protein yield while exerting different impacts in small and shake-flask scales, which indicated that cultivation volume is also an important factor that should be taken into account in optimization process. Furthermore, richness of medium and slower cellular growth rate improved specific cellular yield of functional protein by having a positive effect on the solubility of Fab' antibody.