Practical considerations for nonclinical safety evaluation of therapeutic monoclonal antibodies

Monoclonal antibodies (mAbs) are a well established class of therapeutics as evidenced by a large number of FDA approved mAbs for the treatment of cancers and autoimmune diseases. Monoclonal antibodies that are molecularly engineered for enhanced functions and pharmacokinetic properties are routinely being considered for development by many biotechnology companies. Safety evaluation of current generation of mAbs poses new challenges due to the highly complex nature of engineering aspects and variability induced by the diverse recombinant cell systems to generate them. This review provides a basic outline for nonclinical safety evaluation of therapeutic antibodies. Important considerations for planning a preclinical program, the types of nonclinical safety studies, and a general timeline for their conduct in relation to clinical trials are described. A list of relevant regulatory documents issued by government agencies is also provided. Adoption of these principles will greatly enhance the quality and relevance of the nonclinical safety data generated and will facilitate future development of mAb therapeutics.Key words: monoclonal antibodies, toxicology, therapeutics, nonclinical testing, toxicity studies, pharmacology, biotherapeutics     

Predictive tools for stabilization of therapeutic proteins

Monoclonal antibodies represent the fastest growing class of pharmaceuticals. A major problem, however, is that the proteins are susceptible to aggregation at the high concentration commonly used during manufacturing and storage. Our recent publication describes a technology based on molecular simulations to identify aggregation-prone regions of proteins in silico. The technology, called spatial aggregation propensity (SAP), identifies hot-spots for aggregation based on the dynamic exposure of spatially-adjacent hydrophobic amino acids. Monoclonal antibodies (mAbs) in which patches with high-SAP scores are changed to patches with significantly reduced SAP scores via a single mutation are more stable than wild type, thus validating the SAP method for mapping aggregation-prone regions on proteins. We propose that the SAP technology will be useful for protein stabilization, and as a screening tool to bridge discovery and development of protein-based therapeutics by a rational assessment of the developability of candidate protein drugs.     

Utilization of the human gamma-satellite insulator for the enhancement of anti-PCSK9 monoclonal antibody expression in Chinese hamster ovary cells

Molecular Biology Reports - Monoclonal antibodies (mAbs) are widely employed as invaluable therapeutics for a vast number of human disorders. Several approaches have been introduced for the...     

Metrics for antibody therapeutics development

A wide variety of full-size monoclonal antibodies (mAbs) and therapeutics derived from alternative antibody formats can be produced through genetic and biological engineering techniques. These molecules are now filling the preclinical and clinical pipelines of every major pharmaceutical company and many biotechnology firms. Metrics for the development of antibody therapeutics, including averages for the number of candidates entering clinical study and development phase lengths for mAbs approved in the United States, were derived from analysis of a dataset of over 600 therapeutic mAbs that entered clinical study sponsored, at least in part, by commercial firms. The results presented provide an overview of the field and context for the evaluation of on-going and prospective mAb development programs. The expansion of therapeutic antibody use through supplemental marketing approvals and the increase in the study of therapeutics derived from alternative antibody formats are discussed.     

Immunotoxicity of monoclonal antibodies

Monoclonal antibodies (mAbs) are large molecules intended to bind to specific targets often expressed on the immune system, and to treat various immunopathological conditions. Therefore, mAbs can be considered to have a high potential for immunotoxicity, which is reflected in the clinical experience accumulated on mAbs-induced adverse effects related to immunosuppression, immunostimulation and hypersensitivity (immunogenicity). So far, non clinical immunotoxicity studies have been inadequate to address all safety issues in relation to the possible immunotoxicity of mAbs, because they are fraught with limitations and pitfalls primarily related to the lack of relevant animal species. In addition, clinical studies rarely include validated end-points dedicated to the prediction of immunotoxicity. With the ongoing development of mAbs as novel therapeutic strategies for a wide variety of diseases, efforts should be paid to improve our understanding of mAbs-induced immunotoxic effects and design dedicated strategies to assess their immunological safety, both non clinically and clinically.Key words: immunotoxicology, monoclonal antibodies, immunological safety evaluation     

Target mediated disposition of T84.66, a monoclonal anti-CEA antibody

Monoclonal antibodies (mAbs) as a class of novel oncology therapeutics are demonstrating clinical efficacy as measured by tumor response (shrinkage in tumor size), and prolongations in progression-free survival (PFS) and overall survival (OS). However, clinical benefits are often limited to when antibodies are used in combination with chemotherapy or radiation modalities, with tumor responses only seen in a fraction of patients, and improvements in PFS and OS are incremental (1). The potential of mAbs and mAb constructs has yet to be fully exploited for maximal clinical benefits. New approaches to further improve the effectiveness of these mAb therapies include (a) selection of patients who may derive the most benefit based on the molecular characteristics of their tumors; (b) improvements in biodistribution to maximize delivery of mAbs to susceptible tumor cells; and (c) optimization of antibody immune effector mechanisms such as antibody-dependent cellular cytotoxicity (ADCC).     

单个B细胞抗体制备技术及应用

单克隆抗体是现代生命科学研究的重要工具,为许多领域的发展作出了不可估量的贡献。随着PCR技术和单克隆抗体技术的发展和成熟,单个B细胞抗体制备技术迅速兴起。该技术能够对单个的抗原特异性B细胞进行抗体基因的体外克隆和表达,保证了轻重链可变区的天然配对,相较于传统的抗体制备技术具有效率高、全人源、基因多样性更丰富等优势。单个B细胞抗体制备技术已成为制备全人抗体的热门方法,同时也促进了包括抗体发生成熟、疫苗保护机制、疫苗开发、肿瘤及自身免疫疾病等免疫学相关研究。文中就单个B细胞抗体制备技术的过程及应用作简要综述。     

Antibody drug-conjugates targeting the tumor vasculature

Reducing the blood supply of tumors is one modality to combat cancer. Monoclonal antibodies are now established as a key therapeutic approach for a range of diseases. Owing to the ability of antibodies to selectively target endothelial cells within the tumor vasculature, vascular targeting programs have become a mainstay in oncology drug development. However, the antitumor activity of single agent administration of conventional anti-angiogenic compounds is limited and the improvements in patient survival are most prominent in combinations with chemotherapy. Furthermore, prolonged treatment with conventional anti-angiogenic drugs is associated with toxicity and drug resistance. These circumstances provide a strong rationale for novel approaches to enhance the efficacy of mAbs targeting tumor vasculature such as antibody-drug conjugates (ADCs). Here, we review trends in the development of ADCs targeting tumor vasculature with the aim of informing future research and development of this class of therapeutics.     

Antibody discovery ex vivo accelerated by the LacO/LacI regulatory network

Monoclonal antibodies (mAbs) can be potent and highly specific therapeutics, diagnostics and research reagents. Nonetheless, mAb discovery using current in vivo or in vitro approaches can be costly and time-consuming, with no guarantee of success. We have established a platform for rapid discovery and optimization of mAbs ex vivo. This DTLacO platform derives from a chicken B cell line that has been engineered to enable rapid selection and seamless maturation of high affinity mAbs. We have validated the DTLacO platform by generation of high affinity and specific mAbs to five cell surface targets, the receptor tyrosine kinases VEGFR2 and TIE2, the glycoprotein TROP2, the small TNF receptor family member FN14, and the G protein-coupled receptor FZD10. mAb discovery is rapid and humanization is straightforward, establishing the utility of the DTLacO platform for identification of mAbs for therapeutic and other applications.     

Immunotoxicity of monoclonal antibodies

Monoclonal antibodies (mAbs) are large molecules intended to bind to specific targets often expressed on the immune system, and to treat various immunopathological conditions. Therefore, mAbs can be considered to have a high potential for immunotoxicity, which is reflected in the clinical experience accumulated on mAbs-induced adverse effects related to immunosuppression, immunostimulation, and hypersensitivity (immunogenicity). So far, non clinical immunotoxicity studies have been inadequate to address all safety issues in relation to the possible immunotoxicity of mAbs, because they are fraught with limitations and pitfalls primarily related to the lack of relevant animal species. In addition, clinical studies rarely include validated end-points dedicated to the prediction of immunotoxicity. With the ongoing development of mAbs as novel therapeutic strategies for a wide variety of diseases, efforts should be paid to improve our understanding of mAbs-induced immunotoxic effects and design dedicated strategies to assess their immunological safety, both non clinically and clinically.     

Potent neutralization of botulinum neurotoxin/b by synergistic action of antibodies recognizing protein and ganglioside receptor binding domain

Background

Botulinum neurotoxins (BoNTs), the causative agents for life-threatening human disease botulism, have been recognized as biological warfare agents. Monoclonal antibody (mAb) therapeutics hold considerable promise as BoNT therapeutics, but the potencies of mAbs against BoNTs are usually less than that of polyclonal antibodies (or oligoclonal antibodies). The confirmation of key epitopes with development of effective mAb is urgently needed.

Methods and Findings

We selected 3 neutralizing mAbs which recognize different non-overlapping epitopes of BoNT/B from a panel of neutralizing antibodies against BoNT/B. By comparing the neutralizing effects among different combination groups, we found that 8E10, response to ganglioside receptor binding site, could synergy with 5G10 and 2F4, recognizing non-overlapping epitopes within Syt II binding sites. However, the combination of 5G10 with 2F4 blocking protein receptor binding sites did not achieve synergistical effects. Moreover, we found that the binding epitope of 8E10 was conserved among BoNT A, B, E, and F, which might cross-protect the challenge of different serotypes of BoNTs in vivo.

Conclusions

The combination of two mAbs recognizing different receptors'' binding domain in BoNTs has a synergistic effect. 8E10 is a potential universal partner for the synergistical combination with other mAb against protein receptor binding domain in BoNTs of other serotypes.     

Safety testing of monoclonal antibodies in non-human primates: Case studies highlighting their impact on human risk assessment

Monoclonal antibodies (mAbs) are improving the quality of life for patients suffering from serious diseases due to their high specificity for their target and low potential for off-target toxicity. The toxicity of mAbs is primarily driven by their pharmacological activity, and therefore safety testing of these drugs prior to clinical testing is performed in species in which the mAb binds and engages the target to a similar extent to that anticipated in humans. For highly human-specific mAbs, this testing often requires the use of non-human primates (NHPs) as relevant species. It has been argued that the value of these NHP studies is limited because most of the adverse events can be predicted from the knowledge of the target, data from transgenic rodents or target-deficient humans, and other sources. However, many of the mAbs currently in development target novel pathways and may comprise novel scaffolds with multi-functional domains; hence, the pharmacological effects and potential safety risks are less predictable. Here, we present a total of 18 case studies, including some of these novel mAbs, with the aim of interrogating the value of NHP safety studies in human risk assessment. These studies have identified mAb candidate molecules and pharmacological pathways with severe safety risks, leading to candidate or target program termination, as well as highlighting that some pathways with theoretical safety concerns are amenable to safe modulation by mAbs. NHP studies have also informed the rational design of safer drug candidates suitable for human testing and informed human clinical trial design (route, dose and regimen, patient inclusion and exclusion criteria and safety monitoring), further protecting the safety of clinical trial participants.     

单克隆卵黄抗体技术研究进展

单克隆抗体具有特异性强、表达较稳定等优势,而鸡IgY抗体因其种属距离等特点而具备一系列特殊优势,诸如交叉反应小、产生IgY的鸡免疫系统对哺乳动物保守的生物分子反应明显等,如能将这两种抗体的优势结合起来,开发单克隆卵黄抗体则有望大大拓展抗体的研究模式和应用领域.针对这一新兴领域,从单克隆卵黄抗体的理论背景、研发与技术现状和可能的应用前景三个角度综述了国外的研究现状.     

Mass spectrometry for the biophysical characterization of therapeutic monoclonal antibodies

Monoclonal antibodies (mAbs) are powerful therapeutics, and their characterization has drawn considerable attention and urgency. Unlike small-molecule drugs (150–600 Da) that have rigid structures, mAbs (∼150 kDa) are engineered proteins that undergo complicated folding and can exist in a number of low-energy structures, posing a challenge for traditional methods in structural biology. Mass spectrometry (MS)-based biophysical characterization approaches can provide structural information, bringing high sensitivity, fast turnaround, and small sample consumption. This review outlines various MS-based strategies for protein biophysical characterization and then reviews how these strategies provide structural information of mAbs at the protein level (intact or top-down approaches), peptide, and residue level (bottom-up approaches), affording information on higher order structure, aggregation, and the nature of antibody complexes.     

Challenges and opportunities for the future of monoclonal antibody development: Improving safety assessment and reducing animal use

The market for biotherapeutic monoclonal antibodies (mAbs) is large and is growing rapidly. However, attrition poses a significant challenge for the development of mAbs, and for biopharmaceuticals in general, with large associated costs in resource and animal use. Termination of candidate mAbs may occur due to poor translation from preclinical models to human safety. It is critical that the industry addresses this problem to maintain productivity. Though attrition poses a significant challenge for pharmaceuticals in general, there are specific challenges related to the development of antibody-based products. Due to species specificity, non-human primates (NHP) are frequently the only pharmacologically relevant species for nonclinical safety and toxicology testing for the majority of antibody-based products, and therefore, as more mAbs are developed, increased NHP use is anticipated. The integration of new and emerging in vitro and in silico technologies, e.g., cell- and tissue-based approaches, systems pharmacology and modeling, have the potential to improve the human safety prediction and the therapeutic mAb development process, while reducing and refining animal use simultaneously. In 2014, to engage in open discussion about the challenges and opportunities for the future of mAb development, a workshop was held with over 60 regulators and experts in drug development, mechanistic toxicology and emerging technologies to discuss this issue. The workshop used industry case-studies to discuss the value of the in vivo studies and identify opportunities for in vitro technologies in human safety assessment. From these and continuing discussions it is clear that there are opportunities to improve safety assessment in mAb development using non-animal technologies, potentially reducing future attrition, and there is a shared desire to reduce animal use through minimised study design and reduced numbers of studies.     

Newer approaches to the radiolabeling of monoclonal antibodies by use of metal chelates

Monoclonal antibodies (mAbs) radiolabeled by use of metal chelators are being investigated in the laboratory for use in clinical trials. ¹¹¹In is presently employed for diagnostic scintigraphy, but its applications are limited by substantive and persistant uptake of radiometal in the liver. Much current research is focused on performing cancer therapy with ⁹⁰Y and ²¹²Bi chelate-linked mAbs. This report chronicles the development and evaluation of chelating agents for ¹¹¹In-radioimmunoimaging and ⁹⁰Y-and ²¹²Bi-radioimmunotherapy.     

Antibodies at work in the time of severe acute respiratory syndrome coronavirus 2

In view of devastating effects of COVID-19 on human life, there is an urgent need for the licened vaccines or therapeutics for the SARS-CoV-2 infection. Age-old passive immunization with protective antibodies to neutralize the virus is one of the strategies for emergency prophylaxis and therapy for coronavirus disease 2019 (COVID-19). In this review, the authors discuss up-to-date advances in immune-based therapy for COVID-19. The use of convalescent plasma therapy as the first line of defense to treat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been established, with encouraging results. Monoclonal antibodies (mAbs) that bind to the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein or block the interaction between SARS-CoV-2 RBD and the human angiotensin-converting enzyme 2 receptor have been found to be very promising as a countermeasure for tackling the SARS-CoV-2 infection, and clinical trials are underway. Considering the counterproductive antibody-dependent enhancement of the virus, mAbs therapy that is safe and efficacious, even in people with underlying conditions, will be a significant breakthrough. In addition, emerging immunotherapeutic interventions using nanobodies and cellular immunotherapy are promising avenues for tackling the COVID-19 pandemic. The authors also discuss the implication of mAbs as mediators of cytokine storm syndrome to modify the immune response of COVID-19 patients, thus reducing the fatality rate of COVID-19 infection.     

The growth and potential of human antiviral monoclonal antibody therapeutics

Monoclonal antibodies (mAbs) have long provided powerful research tools for virologists to understand the mechanisms of virus entry into host cells and of antiviral immunity. Even so, commercial development of human (or humanized) mAbs for the prophylaxis, preemptive and acute treatment of viral infections has been slow. This is surprising, as new antibody discovery tools have increased the speed and precision with which potent neutralizing human antiviral mAbs can be identified. As longstanding barriers to antiviral mAb development, such as antigenic variability of circulating viral strains and the ability of viruses to undergo neutralization escape, are being overcome, deeper insight into the mechanisms of mAb action and engineering of effector functions are also improving the efficacy of antiviral mAbs. These successes, in both industrial and academic laboratories, coupled with ongoing changes in the biomedical and regulatory environments, herald an era when the commercial development of human antiviral mAb therapies will likely surge.     

Antibody drug-conjugates targeting the tumor vasculature: Current and future developments

Reducing the blood supply of tumors is one modality to combat cancer. Monoclonal antibodies are now established as a key therapeutic approach for a range of diseases. Owing to the ability of antibodies to selectively target endothelial cells within the tumor vasculature, vascular targeting programs have become a mainstay in oncology drug development. However, the antitumor activity of single agent administration of conventional anti-angiogenic compounds is limited and the improvements in patient survival are most prominent in combinations with chemotherapy. Furthermore, prolonged treatment with conventional anti-angiogenic drugs is associated with toxicity and drug resistance. These circumstances provide a strong rationale for novel approaches to enhance the efficacy of mAbs targeting tumor vasculature such as antibody-drug conjugates (ADCs). Here, we review trends in the development of ADCs targeting tumor vasculature with the aim of informing future research and development of this class of therapeutics.Key words: tumor, vasculature, immunotherapy, antibody-drug conjugates, monoclonal antibody, cancer, angiogenesis