Antibodies2015, 4(3), 240-258; doi:10.3390/antib4030240 - published 1 September 2015 Show/Hide Abstract
Abstract: At 420 million years, the variable domain of New Antigen Receptors or VNARs are undoubtedly the oldest (and smallest) antigen binding single domains identified in the vertebrate kingdom. Their role as an integral part of the adaptive immune system of sharks has been well established and has served to provide a greater understanding of the evolution of humoral immunity; their cellular components and processes as well as the underlying genetic organization and molecular control mechanisms. Intriguingly, unlike the variable domain of the camelid heavy chain antibodies or VHH, VNARs do not conform to all of the characteristic properties of classical antibodies with an ancestral origin that clearly distinguishes them from true immunoglobulin antibodies. However, this uniqueness of their origin only adds to their potential as next generation therapeutic biologics with their structural and functional attributes and commercial freedom all enhancing their profile and current success. In fact their small size, remarkable stability, molecular flexibility and solubility, together with their high affinity and selectivity for target, all reinforce the potential of these domains as drug candidates. The purpose of this review is to provide an overview of the existing basic biology of these unique domains, to highlight the drug-like properties of VNARs and describe current progress in their journey towards the clinic.
Antibodies2015, 4(3), 225-239; doi:10.3390/antib4030225 - published 14 August 2015 Show/Hide Abstract
Abstract: Currently, many peptide vaccines are undergoing clinical studies. Most of these vaccines were developed to activate cytotoxic T cells; however, the response is not robust. Unlike vaccines, anti-cancer antibodies based on passive immunity have been approved as a standard treatment. Since passive immunity is more effective in tumor treatment, the evidence suggests that limited B cell epitope-based peptide vaccines may have similar activity. Nevertheless, such peptide vaccines have not been intensively developed primarily because humoral immunity is thought to be preferable to cancer progression. B cells secrete cytokines, which suppress immune functions. This review discusses the possibility of therapeutic antibody induction by a peptide vaccine and the role of active and passive B cell immunity in cancer patients. We also discuss the use of humanized mice as a pre-clinical model. The necessity of a better understanding of the activity of B cells in cancer is also discussed.
Antibodies2015, 4(3), 197-224; doi:10.3390/antib4030197 - published 3 August 2015 Show/Hide Abstract
Abstract: Monoclonal antibodies (mAbs) and their derivatives are currently the fastest growing class of therapeutics. Even if naked antibodies have proven their value as successful biopharmaceuticals, they suffer from some limitations. To overcome suboptimal therapeutic efficacy, immunoglobulins are conjugated with toxic payloads to form antibody drug conjugates (ADCs) and with chelating systems bearing therapeutic radioisotopes to form radioimmunoconjugates (RICs). Besides their therapeutic applications, antibody conjugates are also extensively used for many in vitro assays. A broad variety of methods to functionalize antibodies with various payloads are currently available. The decision as to which conjugation method to use strongly depends on the final purpose of the antibody conjugate. Classical conjugation via amino acid residues is still the most common method to produce antibody conjugates and is suitable for most in vitro applications. In recent years, however, it has become evident that antibody conjugates, which are generated via site-specific conjugation techniques, possess distinct advantages with regard to in vivo properties. Here, we give a comprehensive overview on existing and emerging strategies for the production of covalent and non-covalent antibody conjugates.
Abstract: Assembly of misfolded proteins into fibrillar deposits is a common feature of many neurodegenerative diseases. Developing effective therapies to these complex, and not yet fully understood diseases is currently one of the greatest medical challenges facing society. Slow and initially asymptomatic onset of neurodegenerative disorders requires profound understanding of the processes occurring at early stages of the disease including identification and structural characterisation of initial toxic species underlying neurodegeneration. In this review, we chart the latest progress made towards understanding the multifactorial process leading to amyloid formation and highlight efforts made in the development of therapeutic antibodies for the treatment of amyloid-based disorders. The specificity and selectivity of conformational antibodies make them attractive research probes to differentiate between transient states preceding formation of mature fibrils and enable strategies for potential therapeutic intervention to be considered.
Abstract: Monoclonal antibodies are generally produced using a generic platform approach in which several chromatographic separations assure high purity of the product. Dimerization can occur during the fermentation stage and may occur also during the downstream processing. We present here simulations in which a traditional platform approach that consist of protein A capture, followed by cation-exchange and anion-exchange chromatography for polishing is compared to a continuous platform in which dimer removal and virus inactivation are carried out on a size-exclusion column. A dimerization model that takes pH, salt concentration and the concentration of antibodies into account is combined with chromatographic models, to be able to predicted both the separation and the degree to which dimers are formed. Purification of a feed composition that contained 1% by weight of dimer and a total antibody concentration of 1 g/L was modeled using both approaches, and the amount of antibodies in the continuous platform was at least 4 times lower than in the traditional platform. The total processing time was also lower, as the cation-exchange polish could be omitted.
Abstract: Nanobodies are antigen-binding, single variable domain proteins derived from naturally-occurring, heavy chain only antibodies. They are highly soluble, stable, and can be linked to build multi-specific formats. Several Nanobodies are currently in clinical development in different therapeutic areas, for both chronic and acute applications. For the former, prolonged exposure is achieved by half-life extending moieties that target endogenous albumin, while for the latter, non-half-life extended constructs are preferable. To demonstrate the general pharmacokinetic behavior of both formats, serum levels of seven intravenously administered Nanobodies were analyzed in cynomolgus monkeys, mice or rabbits. In monkeys, the total clearance of a monomeric irrelevant Nanobody was rapid (2.0 mL/(min*kg)) and approximated the species glomerular filtration rate, indirectly suggesting that the Nanobody was mainly eliminated via the kidneys. When linked to an anti-albumin Nanobody, a 376-fold decrease in clearance was observed, resulting in a terminal half-life of 4.9 days, corresponding to the expected species albumin half-life. Similar conclusions were drawn for (non-) half-life extended mono-, bi- and trimeric Nanobodies in mice or rabbits, suggesting that these kinetic principles apply across species. Applying this knowledge to species translation and study design is crucial for successful pre-clinical development of novel therapeutic Nanobody candidates.