Current Protein Conjugation Strategies and Pioneering Anti-Cancer Applications.

The escalating global impact of cancer demands targeted and efficient therapies. Many targeted cancer therapeutics have been fostered into the market in recent years. The leading class of targeted therapeutics is monoclonal antibodies (mAbs). The success of mAbs sparked significant interest and subsequently paved the way for the development of various recombinant protein-based products that were conjugated to other compounds to form antibody-drug conjugates (ADCs) for the treatment of cancer. This review explores diverse mAb conjugation strategies and pioneering approaches for cancer applications, to optimize drug delivery through site-directed conjugation, prodrug conjugates and antibody conjugated nanoparticles. It also highlights promising innovations and addresses challenges including stability issues of ADCs, drug resistance, payload retention and some of the shortcomings of ADCs such as limited bioavailability, short serum half-life, and reduced drug buildup caused by obstacles in the tumor environment primarily associated with heightened interstitial fluid pressure (IFP).

Anti-Tumor Activity of Novel Nimotuzumab-Functionalized Gold Nanoparticles as a Potential Immunotherapeutic Agent against Skin and Lung Cancers.

The epidermal growth factor receptor (EGFR) is vital for many different types of cancer. Nimotuzumab (NmAb), an anti-EGFR monoclonal antibody (mAb), is used against some of EGFR-overexpressed cancers in various countries. It targets malignant cells and is internalized via receptor-mediated endocytosis. We hypothesized that mAb-nanoparticle conjugation would provide an enhanced therapeutic efficacy, and hence we conjugated NmAb with 27 nm spherical gold nanoparticles (AuNPs) to form AuNP-NmAb nanoconjugates. Using biophysical and spectroscopic methods, including ultraviolet-visible spectroscopy (UV-Vis), transmission electron microscopy (TEM), dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and Fourier-transform infrared spectroscopy (FTIR), the AuNP-NmAb complex was characterized. Furthermore, in vitro studies were performed using a medium-level EGFR-expressing skin cancer cell (A431, EGFRmedium) and low-level EGFR-expressing lung cancer cell (A549, EGFRlow) to evaluate anti-tumor and cellular uptake efficiency via MTT assay and single-particle inductively coupled plasma mass spectrometry (spICP-MS), respectively. In comparison to NmAb monotherapy, the AuNP-NmAb treatment drastically reduced cancer cell survivability: for A431 cells, the IC50 value of AuNP-NmAb conjugate was 142.7 µg/mL, while the IC50 value of free NmAb was 561.3 µg/mL. For A549 cells, the IC50 value of the AuNP-NmAb conjugate was 163.6 µg/mL, while the IC50 value of free NmAb was 1,082.0 µg/mL. Therefore, this study highlights the unique therapeutic potential of AuNP-NmAb in EGFR+ cancers and shows the potential to develop other mAb nanoparticle complexes for a superior therapeutic efficacy.

A Novel Dual-Payload ADC for the Treatment of HER2+ Breast and Colon Cancer.

Antibody-drug conjugates (ADCs) have demonstrated a great therapeutic potential against cancer due to their target specificity and cytotoxicity. To exert a maximum therapeutic effect on cancerous cells, we have conjugated two different payloads to different amino acids, cysteines (cys) and lysines (lys), on trastuzumab, which is a humanised anti-HER2 monoclonal antibody. First, trastuzumab was conjugated with monomethyl auristatin E (MMAE), an antimitotic agent, through a cleavable linker (Val-Cit) to prepare ADC (Tmab-VcMMAE). Then, the ADC (Tmab-VcMMAE) was conjugated with a second antimitotic agent, Mertansine (DM1), via a non-cleavable linker Succinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate (SMCC) to form a dual conjugate (Tmab-VcMMAE-SMCC-DM1). Our results indicated that the dual-payload conjugate, Tmab-VcMMAE-SMCC-DM1, had a synergistic and superior cytotoxic effect compared to trastuzumab alone. Ultimately employing a dual conjugation approach has the potential to overcome treatment-resistance and tumour recurrences and could pave the way to employ other payloads to construct dual (or multiple) payload complexes.

Vaccine Hesitancy: Contemporary Issues and Historical Background.

Vaccination, despite being recognized as one of the most effective primary public health measures, is viewed as unsafe and unnecessary by an increasing number of individuals. Anxiety about vaccines and vaccination programs leading to vaccine hesitancy results from a complex mix of social and political influences, cultural and religious beliefs, the availability of and ability to interpret health and scientific information, and personal and population experiences of health systems and government policies. Vaccine hesitancy is becoming a serious threat to vaccination programs, and was identified as one of the World Health Organization's top ten global health threats in 2019. The negative impact of anti-vaccination movements is frequently cited as one of the major reasons for rising vaccine hesitancy amongst the general public world-wide. This review discusses the various issues surrounding vaccine hesitancy and the anti-vaccine movement, starting with the definitions of vaccine hesitancy and the anti-vaccine movement in their early history and in the modern era, before discussing the key drivers of vaccine hesitancy, particularly across different regions of the world, with a focus on various countries with low-, middle-, or high-income economies with different socio-economic populations. The review concludes with the impact of vaccine hesitancy on herd immunity and social, psychological, and public health measures to counter vaccine hesitancy.

Glycan Profile Analysis of Engineered Trastuzumab with Rationally Added Glycosylation Sequons Presents Significantly Increased Glycan Complexity.

Protein aggregation constitutes a recurring complication in the manufacture and clinical use of therapeutic monoclonal antibodies (mAb) and mAb derivatives. Antibody aggregates can reduce production yield, cause immunogenic reactions, decrease the shelf-life of the pharmaceutical product and impair the capacity of the antibody monomer to bind to its cognate antigen. A common strategy to tackle protein aggregation involves the identification of surface-exposed aggregation-prone regions (APR) for replacement through protein engineering. It was shown that the insertion of N-glycosylation sequons on amino acids proximal to an aggregation-prone region can increase the physical stability of the protein by shielding the APR, thus preventing self-association of antibody monomers. We recently implemented this approach in the Fab region of full-size adalimumab and demonstrated that the thermodynamic stability of the Fab domain increases upon N-glycosite addition. Previous experimental data reported for this technique have lacked appropriate confirmation of glycan occupancy and structural characterization of the ensuing glycan profile. Herein, we mutated previously identified candidate positions on the Fab domain of Trastuzumab and employed tandem mass spectrometry to confirm attachment and obtain a detailed N-glycosylation profile of the mutants. The Trastuzumab glycomutants displayed a glycan profile with significantly higher structural heterogeneity compared to the HEK Trastuzumab antibody, which contains a single N-glycosylation site per heavy chain located in the CH2 domain of the Fc region. These findings suggest that Fab N-glycosites have higher accessibility to enzymes responsible for glycan maturation. Further, we have studied effects on additional glycosylation on protein stability via accelerated studies by following protein folding and aggregation propensities and observed that additional glycosylation indeed enhances physical stability and prevent protein aggregation. Our findings shed light into mAb glycobiology and potential implications in the application of this technique for the development of "biobetter" antibodies.

An Overview of Influenza Viruses and Vaccines.

Influenza remains one of the major public health concerns because it causes annual epidemics and can potentially instigate a global pandemic. Numerous countermeasures, including vaccines and antiviral treatments, are in use against seasonal influenza infection; however, their effectiveness has always been discussed due to the ongoing resistance to antivirals and relatively low and unpredictable efficiency of influenza vaccines compared to other vaccines. The growing interest in vaccines as a promising approach to prevent and control influenza may provide alternative vaccine development options with potentially increased efficiency. In addition to currently available inactivated, live-attenuated, and recombinant influenza vaccines on the market, novel platforms such as virus-like particles (VLPs) and nanoparticles, and new vaccine formulations are presently being explored. These platforms provide the opportunity to design influenza vaccines with improved properties to maximize quality, efficacy, and safety. The influenza vaccine manufacturing process is also moving forward with advancements relating to egg- and cell-based production, purification processes, and studies into the physicochemical attributes and vaccine degradation pathways. These will contribute to the design of more stable, optimized vaccine formulations guided by contemporary analytical testing methods and via the implementation of the latest advances in the field.

Vaccines and vaccination: history and emerging issues.

Prophylactic vaccines are crucial in modern healthcare and have been used successfully to combat bacterial and viral infectious diseases. Infections like polio and smallpox, which were dreaded historically, and which devastated the human race over many centuries, are now rare. Smallpox has been eradicated completely and polio is nearly eradicated because of vaccines. Vaccines differ fundamentally from other classes of medicines in that they are usually administered as a preventive measure to a healthy individual rather than to a sick person already with an infection, although exceptions to this practice exist. Most currently used prophylactic vaccines are based on established platforms, but many vaccine candidates, in late development stages, including several COVID-19 vaccines, use highly novel vaccine platforms not available historically. History of infectious diseases and prophylactic vaccines are filled with important scientific lessons, and thus provide valuable insights for the future. With hindsight, historically there were some ethically questionable approaches to testing vaccines and the germ warfare against native populations in the Americas and other regions. In this review, we examine key historical lessons learned with prophylactic vaccines with reflections on current healthcare dilemmas and controversies with respect to influenza and COVID-19 vaccines.

Advances and Limitations of Antibody Drug Conjugates for Cancer.

The popularity of antibody drug conjugates (ADCs) has increased in recent years, mainly due to their unrivalled efficacy and specificity over chemotherapy agents. The success of the ADC is partly based on the stability and successful cleavage of selective linkers for the delivery of the payload. The current research focuses on overcoming intrinsic shortcomings that impact the successful development of ADCs. This review summarizes marketed and recently approved ADCs, compares the features of various linker designs and payloads commonly used for ADC conjugation, and outlines cancer specific ADCs that are currently in late-stage clinical trials for the treatment of cancer. In addition, it addresses the issues surrounding drug resistance and strategies to overcome resistance, the impact of a narrow therapeutic index on treatment outcomes, the impact of drug-antibody ratio (DAR) and hydrophobicity on ADC clearance and protein aggregation.

Recent Advances in the Use of Iron-Gold Hybrid Nanoparticles for Biomedical Applications.

Recently, there has been an increased interest in iron-gold-based hybrid nanostructures, due to their combined outstanding optical and magnetic properties resulting from the usage of two separate metals. The synthesis of these nanoparticles involves thermal decomposition and modification of their surfaces using a variety of different methods, which are discussed in this review. In addition, different forms such as core-shell, dumbbell, flower, octahedral, star, rod, and Janus-shaped hybrids are discussed, and their unique properties are highlighted. Studies on combining optical response in the near-infrared window and magnetic properties of iron-gold-based hybrid nanoparticles as multifunctional nanoprobes for drug delivery, magnetic-photothermal heating as well as contrast agents during magnetic and optical imaging and magnetically-assisted optical biosensing to detect traces of targeted analytes inside the body has been reviewed.

A Narrative Review of COVID-19 Vaccines.

The COVID-19 pandemic has shaken the world since early 2020 and its health, social, economic, and societal negative impacts at the global scale have been catastrophic. Since the early days of the pandemic, development of safe and effective vaccines was judged to be the best possible tool to minimize the effects of this pandemic. Drastic public health measures were put into place to stop the spread of the virus, with the hope that vaccines would be available soon. Thanks to the extraordinary commitments of many organizations and individuals from around the globe and the collaborative effort of many international scientists, vaccines against COVID-19 received regulatory approval for emergency human use in many jurisdictions in less than a year after the identification of the viral sequence. Several of these vaccines have been in use for some time; however, the pandemic is still ongoing and likely to persist for the foreseeable future. This is due to many reasons including reduced compliance with public health restrictions, limited vaccine manufacturing/distribution capacity, high rates of vaccine hesitancy, and the emergence of new variants with the capacity to spread more easily and to evade current vaccines. Here we discuss the discovery and availability of COVID-19 vaccines and evolving issues around mass vaccination programs.

Enhancing the stability of adalimumab by engineering additional glycosylation motifs.

Monoclonal antibodies (mAbs) are of high value in the diagnostic and treatment of many debilitating diseases such as cancers, auto-immune disorders and infections. Unfortunately, protein aggregation is one of the ongoing challenges, limiting the development and application of mAbs as therapeutic products by decreasing half-life, increasing immunogenicity and reducing activity. We engineered an aggregation-prone region of adalimumab, the top selling mAb product worldwide - with additional glycosylation sites to enhance its resistance to aggregation by steric hindrance as a next generation biologic. We found that the addition of N-glycans in the Fab domain significantly enhanced its conformational stability, with some variants increasing the melting temperature of the Fab domain by >6 °C. The mutations tested had minimal impact on antigen binding affinity, or affinity to Fcγ receptors responsible for effector function. Our findings highlight the significant utility of this rational engineering approach for enhancing the conformational stability of therapeutic mAbs and other next-generation antibody formats.

A Brief History of Ebolavirus Disease: Paving the Way Forward by Learning from the Previous Outbreaks.

In this review, Ebolavirus Disease (EVD) outbreaks have been comprehensively reviewed from their beginning until now. It chronologically discusses how each outbreak was tackled, national and international actions taken, diagnostic methods applied, the infection control procedures put in place, and the lessons learnt from each epidemic for the control of subsequent epidemics. Data for this review were obtained from literature published between 1967 and 2016 in key medical databases, the official websites of various governmental organisations, international public health agencies, and regulatory bodies. Despite major developments in the field of EVD, there has been little progress in its specific therapy or prevention. Historically, individuals who recovered from EVD acted as a source of fresh frozen plasma (containing IgG) that has been used to treat other acutely ill patients, however this therapeutic modality has limitations due to the risk of transmission of blood-borne infections. With the use of advanced and efficient purification methods the incidence of unwanted side effects following immune serum therapy has currently been greatly reduced. Creation of a safe plasma pool that covers immunoglobulins against all strains of EVD is now a research priority. Recommendations on how future EVD outbreaks can be better managed have been discussed.

Current Advancements in Addressing Key Challenges of Therapeutic Antibody Design, Manufacture, and Formulation.

Therapeutic antibody technology heavily dominates the biologics market and continues to present as a significant industrial interest in developing novel and improved antibody treatment strategies. Many noteworthy advancements in the last decades have propelled the success of antibody development; however, there are still opportunities for improvement. In considering such interest to develop antibody therapies, this review summarizes the array of challenges and considerations faced in the design, manufacture, and formulation of therapeutic antibodies, such as stability, bioavailability and immunological engagement. We discuss the advancement of technologies that address these challenges, highlighting key antibody engineered formats that have been adapted. Furthermore, we examine the implication of novel formulation technologies such as nanocarrier delivery systems for the potential to formulate for pulmonary delivery. Finally, we comprehensively discuss developments in computational approaches for the strategic design of antibodies with modulated functions.

Synthesis and Enhanced Cellular Uptake In Vitro of Anti-HER2 Multifunctional Gold Nanoparticles.

Nanoparticle carriers offer the possibility of enhanced delivery of therapeutic payloads in tumor tissues due to tumor-selective accumulation through the enhanced permeability and retention effect (EPR). Gold nanoparticles (AuNP), in particular, possess highly appealing features for development as nanomedicines, such as biocompatibility, tunable optical properties and a remarkable ease of surface functionalization. Taking advantage of the latter, several strategies have been designed to increase treatment specificity of gold nanocarriers by attaching monoclonal antibodies on the surface, as a way to promote selective interactions with the targeted cells-an approach referred to as active-targeting. Here, we describe the synthesis of spherical gold nanoparticles surface-functionalized with an anti-HER2 antibody-drug conjugate (ADC) as an active targeting agent that carries a cytotoxic payload. In addition, we enhanced the intracellular delivery properties of the carrier by attaching a cell penetrating peptide to the active-targeted nanoparticles. We demonstrate that the antibody retains high receptor-affinity after the structural modifications performed for drug-conjugation and nanoparticle attachment. Furthermore, we show that antibody attachment increases cellular uptake in HER2 amplified cell lines selectively, and incorporation of the cell penetrating peptide leads to a further increase in cellular internalization. Nanoparticle-bound antibody-drug conjugates retain high antimitotic potency, which could contribute to a higher therapeutic index in high EPR tumors.

Monoclonal antibody therapy of solid tumors: clinical limitations and novel strategies to enhance treatment efficacy.

Monoclonal antibodies (mAbs) have become a cornerstone in the therapeutic guidelines of a wide range of solid tumors. The targeted nature of these biotherapeutics has improved treatment outcomes by offering enhanced specificity to reduce severe side effects experienced with conventional chemotherapy. Notwithstanding, poor tumor tissue penetration and the heterogeneous distribution achieved therein are prominent drawbacks that hamper the clinical efficacy of therapeutic antibodies. Failure to deliver efficacious doses throughout the tumor can lead to treatment failure and the development of acquired resistance mechanisms. Comprehending the morphological and physiological characteristics of solid tumors and their microenvironment that affect tumor penetration and distribution is a key requirement to improve clinical outcomes and realize the full potential of monoclonal antibodies in oncology. This review summarizes the essential architectural characteristics of solid tumors that obstruct macromolecule penetration into the targeted tissue following systemic delivery. It further describes mechanisms of resistance elucidated for blockbuster antibodies for which extensive clinical data exists, as a way to illustrate various modes in which cancer cells can overcome the anticancer activity of therapeutic antibodies. Thereafter, it describes novel strategies designed to improve clinical outcomes of mAbs by increasing potency and/or improving tumor delivery; focusing on the recent clinical success and growing clinical pipeline of antibody-drug conjugates, immune checkpoint inhibitors and nanoparticle-based delivery systems.

Preparation-free method can enable rapid surfactant screening during industrial processing of influenza vaccines.

Triton X-100 (TX-100) is the most common surfactant used to split viruses during the production of influenza split-virus vaccines. It is a mild surfactant not known to denature the viral proteins; this property makes TX-100 useful for maintaining antigen conformational structure, and, as an added benefit, for partially stabilizing vaccine formulations against protein aggregation. Despite its benefits, TX-100 needs to be filtered out after virus splitting has been achieved, due to its toxicity in large quantities. Accordingly, residual TX-100 presence in vaccine formulations has implications for both formulation stability and safety, necessitating both accurate screening during processing to guide decision-making about filtration repeats and accurate quantitation in the final product. Accurate HPLC-based methods are used successfully for the latter but their use for routine screening during processing is far from ideal because they often require extensive sample preparation and are fairly slow, complicated and costly. Here, "deconstruction" of UV-Vis absorption spectra into components corresponding to different absorbing "species" is demonstrated as a novel and viable method for routine TX-100 screening in vaccine samples from different industrial processing steps. This method is fairly accurate and, more importantly, preparation-free, rapid, simple/user-friendly and comparatively inexpensive. It is evaluated in depth in terms of applicability conditions, limitations and potential for high-throughput adaptation as well as generalization to other complex biopharmaceutical formulations.

Choline ionic liquid enhances the stability of Herceptin® (trastuzumab).

We investigated the effect of an emerging biocompatible ionic liquid, choline dihydrogen phosphate (CDHP), on the stability of high-concentration formulations of Herceptin® (trastuzumab). Our results show that CDHP significantly suppresses unfolding and aggregation of trastuzumab, demonstrating great promise as an additive in the development of stable therapeutic antibody formulations.

Demonstration of In Vitro Host-Guest Complex Formation and Safety of para-Sulfonatocalix[8]arene as a Delivery Vehicle for Two Antibiotic Drugs.

The macrocycle para-sulfonatocalix[8]arene, sCX[8], was examined with 2 antibiotic drugs, ciprofloxacin (CIP) and isoniazid. The drugs were shown to form complexes with sCX[8] using proton nuclear magnetic resonance, thermogravimetric analysis, fluorescence spectroscopy, and molecular modeling. Both drugs form 1:1 hydrated (H2O: 13%-14% w/w) host-guest complexes, with sCX[8] binding around the pyridine ring of isoniazid, and around the piperazine and cyclopropane rings of CIP. From proton nuclear magnetic resonance, the binding constant of isoniazid to sCX[8] was 6.8 (±0.3) × 103 M-1. Addition of 2 equivalents of sCX[8] to CIP resulted in a 58% decrease in fluorescence, and time-resolved fluorescence anisotropy of CIP doubles with sCX[8]. Each drug binds into the cavity of the macrocycle, with binding stabilized via combinations of hydrogen bonding, electrostatic interactions, π-π stacking, and hydrophobic effects. The safety of sCX[8] was examined in vitro with human embryonic kidney 293 cells. The IC50 of sCX[8] was 559 µM, which is a minimum of 5-fold higher than the concentration that would be used in the clinic. The in vitro effect of sCX[8] on the action of CIP was examined on a panel of bacterial lines. The results showed that sCX[8] has no inherent antibiotic activity and had no negative effect on the action of CIP.

Ionic liquids as biocompatible stabilizers of proteins.

Ionic liquids (ILs) have recently emerged as versatile solvents and additives in the field of biotechnology, particularly as stabilizers of proteins and enzymes. Of interest to the biotechnology industry is the formulation of stable biopharmaceuticals, therapeutic proteins, and vaccines which have revolutionized the treatment of many diseases including debilitating conditions such as cancers and auto-immune diseases. The stabilization of therapeutic proteins is typically achieved using additives that prevent unfolding and aggregation of these proteins during manufacture, transport, and long-term storage. To determine if ILs could be used in the formulation of stable therapeutic proteins, a thorough understanding of the effects of ILs on protein stability is needed, as well as understanding the toxicity of ILs on humans, and other considerations for formulation development such as viscosity and osmolality. In this review, we summarize recent developments on the stabilization of proteins and enzymes using ILs, with emphasis on identifying biocompatible ILs that may be suitable for the formulation of stable biopharmaceuticals in the future.