Monoclonal antibodies - a proven and rapidly expanding therapeutic modality for human diseases

Biodistribution and function of coupled polymer-DNA origami nanostructures

Spatial control over the distribution of therapeutics is a highly desired feature, which could limit the side effects of many drugs. Here we describe a nanoscale agent, fabricated from a coupled polymer-DNA origami hybrid that exhibits stability in serum and slow diffusion through tissues, in a manner correlating with shape and aspect ratio. Coupling to fragments of polyethylene glycol (PEG) through polyamine electrostatic interactions resulted in marked stability of the agents in-vivo, with > 90% of the agents maintaining structural integrity 5 days following subcutaneous injection. An agent functionalized with aptamers specific for human tumor necrosis factor TNF-alpha, significantly abrogated the inflammatory response in a delayed-type hypersensitivity model in humanized TNF-alpha mice. These findings highlight polymer-DNA hybrid nanostructures as a programmable and pharmacologically viable update to mainstream technologies such as monoclonal antibodies, capable of exerting an additional layer of control across the spatial dimension of drug activity.

Development and Biophysical Characterization of a Humanized FSH-Blocking Monoclonal Antibody Therapeutic Formulated at an Ultra-High Concentration

Highly concentrated antibody formulations are oftentimes required for subcutaneous, self-administered biologics. Here, we report the creation of a unique formulation for our first-in- class FSH-blocking humanized antibody, MS-Hu6, which we propose to move to the clinic for osteoporosis, obesity, and Alzheimer's disease. The studies were carried out using our Good Laboratory Practice (GLP) platform, compliant with the Code of Federal Regulations (Title 21, Part 58). We first used protein thermal shift, size exclusion chromatography, and dynamic light scattering to examine MS-Hu6 concentrations between 1 and 100 mg/mL. We found that thermal, monomeric, and colloidal stability of formulated MS-Hu6 was maintained at a concentration of 100 mg/mL. The addition of the antioxidant L-methionine and chelating agent disodium EDTA improved the formulation's long-term colloidal and thermal stability. Thermal stability was further confirmed by Nano differential scanning calorimetry (DSC). Physiochemical properties of formulated MS-Hu6, including viscosity, turbidity, and clarity, conformed with acceptable industry standards. That the structural integrity of MS-Hu6 in formulation was maintained was proven through Circular Dichroism (CD) and Fourier Transform Infrared (FTIR) spectroscopy. Three rapid freeze-thaw cycles at -80°C/25°C or -80°C/37°C further revealed excellent thermal and colloidal stability. Furthermore, formulated MS-Hu6, particularly its Fab domain, displayed thermal and monomeric storage stability for more than 90 days at 4°C and 25°C. Finally, the unfolding temperature (T _m ) for formulated MS-Hu6 increased by >4.80°C upon binding to recombinant FSH, indicating highly specific ligand binding. Overall, we document the feasibility of developing a stable, manufacturable and transportable MS-Hu6 formulation at a ultra-high concentration at industry standards. The study should become a resource for developing biologic formulations in academic medical centers.

Optimizing a therapeutic humanized follicle-stimulating hormone-blocking antibody formulation by protein thermal shift assay

Biopharmaceutical products are formulated using several Food and Drug Administration (FDA) approved excipients within the inactive ingredient limit to maintain their storage stability and shelf life. Here, we have screened and optimized different sets of excipient combinations to yield a thermally stable formulation for the humanized follicle-stimulating hormone (FSH)-blocking antibody, MS-Hu6. We used a protein thermal shift assay in which rising temperatures resulted in the maximal unfolding of the protein at the melting temperature (T_m ). To determine the buffer and pH for a stable solution, four different buffers with a pH range from 3 to 8 were screened. This resulted in maximal T_m s at pH 5.62 for Fab in phosphate buffer and at pH 6.85 for Fc in histidine buffer. Upon testing a range of salt concentrations, MS-Hu6 was found to be more stable at lower concentrations, likely due to reduced hydrophobic effects. Molecular dynamics simulations revealed a higher root-mean-square deviation with 1 mM than with 100 mM salt, indicating enhanced stability, as noted experimentally. Among the stabilizers tested, Tween 20 was found to yield the highest T_m and reversed the salt effect. Among several polyols/sugars, trehalose and sucrose were found to produce higher thermal stabilities. Finally, binding of recombinant human FSH to MS-Hu6 in a final formulation (20 mM phosphate buffer, 1 mM NaCl, 0.001% w/v Tween 20, and 260 mM trehalose) resulted in a thermal shift (increase in T_m ) for the Fab, but expectedly not in the Fc domain. Given that we used a low dose of MS-Hu6 (1 μM), the next challenge would be to determine whether 100-fold higher, industry-standard concentrations are equally stable.

Computational counterselection identifies nonspecific therapeutic biologic candidates

Effective biologics require high specificity and limited off-target binding, but these properties are not guaranteed by current affinity-selection-based discovery methods. Molecular counterselection against off targets is a technique for identifying nonspecific sequences but is experimentally costly and can fail to eliminate a large fraction of nonspecific sequences. Here, we introduce computational counterselection, a framework for removing nonspecific sequences from pools of candidate biologics using machine learning models. We demonstrate the method using sequencing data from single-target affinity selection of antibodies, bypassing combinatorial experiments. We show that computational counterselection outperforms molecular counterselection by performing cross-target selection and individual binding assays to determine the performance of each method at retaining on-target, specific antibodies and identifying and eliminating off-target, nonspecific antibodies. Further, we show that one can identify generally polyspecific antibody sequences using a general model trained on affinity data from unrelated targets with potential affinity for a broad range of sequences.

Retrospective analysis of the preparation and application of immunotherapy in cancer treatment (Review)

Monoclonal antibody technology plays a vital role in biomedical and immunotherapy, which greatly promotes the study of the structure and function of genes and proteins. To date, monoclonal antibodies have gone through four stages: murine monoclonal antibody, chimeric monoclonal antibody, humanised monoclonal antibody and fully human monoclonal antibody; thousands of monoclonal antibodies have been used in the fields of biology and medicine, playing a special role in the pathogenesis, diagnosis and treatment of disease. In this review, we compare the advantages and disadvantages of hybridoma technology, phage display technology, ribosome display technology, transgenic mouse technology, single B cell monoclonal antibody generation technologies, and forecast the promising applications of these technologies in clinical medicine, disease diagnosis and tumour treatment.

Vaccination in patients under monoclonal antibody treatment: an updated comprehensive review

INTRODUCTION

Monoclonal antibodies (mAbs) have become an increasing source of biological treatments. Clinicians should make an effort to update their knowledge on mechanisms of action, indications, and adverse events of these novel therapies. Most of them have immunosuppressive effects and, therefore, vaccination is indicated.

AREAS COVERED

vaccination of patients under mAbs therapies.

EXPERT OPINION

Recommendations on vaccination are still based on expert recommendations and have not been updated in recent years. Specific recommendations for each mAb have not been addressed in the current literature. The aim of this comprehensive review was to collect all the therapeutic mAbs approved up to 1 January 2020 and, based on previous recommendations and the pharmaceutical characteristics of each drug, to propose an updated guide with recommendations on vaccination. Influenza, sequential pneumococcal and Hepatitis B vaccination in patients with negative serology were the only consistent recommendations. Hepatitis A vaccination was proposed for mAbs with special hepatotoxic characteristics. Other vaccines are reviewed and discussed. Several non-immunosuppressive mAbs were detected and, therefore, vaccinations not recommended. We hope that this review can serve as a starting point for compiling updated vaccination recommendations and collecting all the therapeutic mAbs approved up to 2020.

Spatially Resolved Effects of Protein Freeze-Thawing in a Small-Scale Model Using Monoclonal Antibodies

Protein freeze-thawing is frequently used to stabilize and store recombinantly produced proteins after different unit operations in upstream and downstream processing. However, freeze-thawing is often accompanied by product damage and, hence, loss of product. Different effects are responsible, including cold denaturation, aggregation effects, which are caused by inhomogeneities in protein concentration, as well as pH and buffer ingredients, especially during the freeze cycle. In this study, we tested a commercially available small-scale protein freezing unit using immunoglobin G (IgG) as monoclonal antibody in a typical formulation buffer containing sodium phosphate, sodium chloride, and Tween 80. Different freezing rates were used respectively, and the product quality was tested in the frozen sample. Spatially resolved tests for protein concentration, pH, conductivity, and aggregation revealed high spatial differences in the frozen sample. Usage of slow freezing rates revealed high inhomogeneities in terms of buffer salt and protein distribution, while fast rates led to far lower spatial differences. These protein and buffer salt inhomogeneities can be reliably monitored using straight forward analytics, like conductivity and photometric total protein concentration measurements, reducing the need for HPLC analytics in screening experiments. Summarizing, fast freezing using steep rates shows promising results concerning homogeneity of the final frozen product and inhibits increased product aggregation.

Preparation of monoclonal antibody against human KIAA0100 protein and Northern blot analysis of human KIAA0100 gene

Monoclonal antibodies (MAbs) are important tools for the study of proteins' function and structure. But there has been no report on the preparation of MAbs against human KIAA0100 protein up to date. Here, first, we generated the mouse MAb against human KIAA0100 protein using purified recombinant 6×Histidinc (6×His)-tagged human KIAA0100 protein segment (1557-2234) as an antigen; then, the mRNA expression of human KIAA0100 gene was detected in U937 cells using Northern blot analysis. The results showed that the mouse MAb against human KIAA0100 protein could sensitively recognize the human KIAA0100 protein using Western blot analysis and immunocytochemistry analysis. Besides, Western blot analysis revealed that human KIAA0100 gene possibly encoded two different protein products (254 kDa and <250 kDa) in U937 cells. Moreover, Northern blot analysis confirmed that human KIAA0100 gene might produced two different mRNA products (6000-10000 bp and 5000-6000 bp) in U937 cells. The results provide a basis for large-scale production of the MAb against human KIAA0100 protein, which will be useful for the study of human KIAA0100 protein's function/structure and MAb-targeted drugs in the future.

Identification and verification of hybridoma-derived monoclonal antibody variable region sequences using recombinant DNA technology and mass spectrometry

Antibody engineering requires the identification of antigen binding domains or variable regions (VR) unique to each antibody. It is the VR that define the unique antigen binding properties and proper sequence identification is essential for functional evaluation and performance of recombinant antibodies (rAb). This determination can be achieved by sequence analysis of immunoglobulin (Ig) transcripts obtained from a monoclonal antibody (MAb) producing hybridoma and subsequent expression of a rAb. However the polyploidy nature of a hybridoma cell often results in the added expression of aberrant immunoglobulin-like transcripts or even production of anomalous antibodies which can confound production of rAb. An incorrect VR sequence will result in a non-functional rAb and de novo assembly of Ig primary structure without a sequence map is challenging. To address these problems, we have developed a methodology which combines: 1) selective PCR amplification of VR from both the heavy and light chain IgG from hybridoma, 2) molecular cloning and DNA sequence analysis and 3) tandem mass spectrometry (MS/MS) on enzyme digests obtained from the purified IgG. Peptide analysis proceeds by evaluating coverage of the predicted primary protein sequence provided by the initial DNA maps for the VR. This methodology serves to both identify and verify the primary structure of the MAb VR for production as rAb.

Interleukin-6 Inhibition in Inflammatory Diseases: Results Achieved and Tasks to Accomplish

Interleukin-6 (IL-6) is a prototypical cytokine featuring functional pleiotropy and redundancy. Under situations of stress, such as infection or tissue injury, IL-6 is rapidly synthesized and plays a major role in host defense. However, uncontrolled excessive or persistent production of IL-6 has a pathological effect in various diseases. Thus, IL-6 blockade was expected to become a novel therapeutic strategy for IL-6–mediated inflammatory diseases, and the first-in-class IL-6 inhibitor tocilizumab, which blocks IL-6 activity by inhibiting IL-6 binding to its receptor, was developed. Clinical trials of tocilizumab have verified its efficacy and tolerable safety profile in several diseases, and it has been approved for the treatment of patients with rheumatoid arthritis, Castleman's disease, systemic and polyarticular juvenile idiopathic arthritis, and giant cell arteritis. Off-label use and clinical trials strongly indicate that tocilizumab will be applicable for a wide variety of acute and chronic inflammatory diseases.

Elucidating the weak protein-protein interaction mechanisms behind the liquid-liquid phase separation of a mAb solution by different types of additives

Liquid-liquid phase separation (LLPS) has long been observed during the physical stability investigation of therapeutic protein formulations. The buffer conditions and the presence of various excipients are thought to play important roles in the formulation development of monoclonal antibodies (mAbs). In this study, the effects of several small-molecule excipients (histidine, alanine, glycine, sodium phosphate, sodium chloride, sorbitol and sucrose) with diverse physical-chemical properties on LLPS of a model IgG1 (JM2) solutions were investigated by multiple techniques, including UV-vis spectroscopy, circular dichroism, differential scanning calorimetry/fluorimetry, size exclusion chromatography and dynamic light scattering. The LLPS of JM2 was confirmed to be a thermodynamic equilibrium process with no structural changes or irreversible aggregation of proteins. Phase diagrams of various JM2 formulations were constructed, suggesting that the phase behavior of JM2 was dependent on the solution pH, ionic strength and the presence of other excipients such as glycine, alanine, sorbitol and sucrose. Furthermore, we demonstrated that for this mAb, the interaction parameter (k_D) determined at low protein concentration appeared to be a good predictor for the occurrence of LLPS at high concentration.

Molecular and functional analysis of monoclonal antibodies in support of biologics development

Monoclonal antibody (mAb)-based therapeutics are playing an increasingly important role in the treatment or prevention of many important diseases such as cancers, autoimmune disorders, and infectious diseases. Multi-domain mAbs are far more complex than small molecule drugs with intrinsic heterogeneities. The critical quality attributes of a given mAb, including structure, post-translational modifications, and functions at biomolecular and cellular levels, need to be defined and profiled in details during the developmental phases of a biologics. These critical quality attributes, outlined in this review, serve an important database for defining the drug properties during commercial production phase as well as post licensure life cycle management. Specially, the molecular characterization, functional assessment, and effector function analysis of mAbs, are reviewed with respect to the critical parameters and the methods used for obtaining them. The three groups of analytical methods are three essential and integral facets making up the whole analytical package for a mAb-based drug. Such a package is critically important for the licensure and the post-licensure life cycle management of a therapeutic or prophylactic biologics. In addition, the basic principles on the evaluation of biosimilar mAbs were discussed briefly based on the recommendations by the World Health Organization.

A Formulation Development Approach to Identify and Select Stable Ultra-High-Concentration Monoclonal Antibody Formulations With Reduced Viscosities

High protein concentration formulations are required for low-volume administration of therapeutic antibodies targeted for subcutaneous, self-administration by patients. Ultra-high concentrations (≥150 mg/mL) can lead to dramatically increased solution viscosities, which in turn can lead to stability, manufacturing, and delivery challenges. In this study, various categories and individual types of pharmaceutical excipients and other additives (56 in total) were screened for their viscosity reducing effects on 2 different mAbs. The physicochemical stability profile, as well as viscosity ranges, of several candidate antibody formulations, identified and designed based on the results of the excipient screening, were evaluated over a 6-month time period under accelerated and real-time storage conditions. In addition to reducing the solution viscosities to acceptable levels for parenteral administration (using currently available and acceptable delivery devices), the candidate formulations did not result in notable losses of physicochemical stability of the 2 antibodies on storage for 6 months at 25°C. The experiments described here demonstrate the feasibility of a formulation development and selection approach to identify candidate high-concentration antibody formulations with viscosities within pharmaceutically acceptable ranges that do not adversely affect their physicochemical storage stability.

Developments in therapy with monoclonal antibodies and related proteins

Monoclonal antibody therapeutics have been approved for over 30 targets and diseases, most commonly cancer. Antibodies have become the new backbone of the pharmaceutical industry, which previously relied on small molecules. Compared with small molecules, monoclonal antibodies (mAbs) have exquisite target selectivity and hence less toxicity as a result of binding other targets. The clinical value of both mAbs and ligand traps has been proven. New applications of mAbs are being tested and mAbs have now been designed to target two (bi-specific, eg TNF-α and IL-17) or more targets simultaneously, augmenting their therapeutic potential. Because of space limitations and the wide ranging scope of this review there are regrettably, but inevitably, omissions and missing citations. We have chosen to highlight the first successes in inflammatory diseases and cancer, but a broader overview of approved mAbs and related molecules can be found in Table 1.

Antibody-drug conjugates: recent advances in conjugation and linker chemistries

The antibody-drug conjugate (ADC), a humanized or human monoclonal antibody conjugated with highly cytotoxic small molecules (payloads) through chemical linkers, is a novel therapeutic format and has great potential to make a paradigm shift in cancer chemotherapy. This new antibody-based molecular platform enables selective delivery of a potent cytotoxic payload to target cancer cells, resulting in improved efficacy, reduced systemic toxicity, and preferable pharmacokinetics (PK)/pharmacodynamics (PD) and biodistribution compared to traditional chemotherapy. Boosted by the successes of FDA-approved Adcetris^® and Kadcyla^®, this drug class has been rapidly growing along with about 60 ADCs currently in clinical trials. In this article, we briefly review molecular aspects of each component (the antibody, payload, and linker) of ADCs, and then mainly discuss traditional and new technologies of the conjugation and linker chemistries for successful construction of clinically effective ADCs. Current efforts in the conjugation and linker chemistries will provide greater insights into molecular design and strategies for clinically effective ADCs from medicinal chemistry and pharmacology standpoints. The development of site-specific conjugation methodologies for constructing homogeneous ADCs is an especially promising path to improving ADC design, which will open the way for novel cancer therapeutics.

Efficient Qualitative and Quantitative Determination of Antigen-induced Immune Responses

To determine the effectiveness of immunization strategies used in therapeutic antibody or vaccine development, it is critical to assess the quality of immunization-induced polyclonal antibody responses. Here, we developed a workflow that uses sensitive methods to quantitatively and qualitatively assess immune responses against foreign antigens with regard to antibody binding affinity and epitope diversity. The application of such detailed assessments throughout an immunization campaign can significantly reduce the resources required to generate highly specific antibodies. Our workflow consists of the following two steps: 1) the use of surface plasmon resonance to quantify antigen-specific antibodies and evaluate their apparent binding affinities, and 2) the recovery of serum IgGs using an automated small scale purification system, followed by the determination of their epitope diversity using hydrogen deuterium exchange coupled with mass spectrometry. We showed that these methods were sensitive enough to detect antigen-specific IgGs in the nanogram/μl range and that they provided information for differentiating the antibody responses of the various immunized animals that could not be obtained by conventional methods. We also showed that this workflow can guide the selection of an animal that produces high affinity antibodies with a desired epitope coverage profile, resulting in the generation of potential therapeutic monoclonal antibody clones with desirable functional profiles. We postulate that this workflow will be an important tool in the development of effective vaccines to combat the highly sophisticated evasion mechanisms of pathogens.

Gastric inhibitory polypeptide immunoneutralization attenuates development of obesity in mice

Previous reports have suggested that the abrogation of gastric inhibitory polypeptide (GIP) signaling could be exploited to prevent and treat obesity and obesity-related disorders in humans. This study was designed to determine whether immunoneutralization of GIP, using a newly developed specific monoclonal antibody (mAb), would prevent the development of obesity. Specific mAb directed against the carboxy terminus of mouse GIP was identified, and its effects on the insulin response to oral and to intraperitoneal (ip) glucose and on weight gain were evaluated. Administration of mAb (30 mg/kg body wt, BW) to mice attenuated the insulin response to oral glucose by 70% and completely eliminated the response to ip glucose coadministered with human GIP. Nine-week-old C57BL/6 mice injected with GIP mAbs (60 mg·kg BW(-1)·wk(-1)) for 17 wk gained 46.5% less weight than control mice fed an identical high-fat diet (P < 0.001). No significant differences in the quantity of food consumed were detected between the two treatment groups. Furthermore, magnetic resonance imaging demonstrated that subcutaneous, omental, and hepatic fat were 1.97-, 3.46-, and 2.15-fold, respectively, lower in mAb-treated animals than in controls. Moreover, serum insulin, leptin, total cholesterol (TC), low-density lipoprotein (LDL), and triglycerides were significantly reduced, whereas the high-density lipoprotein (HDL)/TC ratio was 1.25-fold higher in treated animals than in controls. These studies support the hypothesis that a reduction in GIP signaling using a GIP-neutralizing mAb might provide a useful method for the treatment and prevention of obesity and related disorders.

Analysis of the Current Situation of Antitumor Drug Use in China: A Hospital-Based Perspective

OBJECTIVE

To present a systematic review of the usage of antitumor drugs in Chinese hospitals from 2009 to 2011.

METHODS

The market data of antitumor drugs was collected from the Menet database that covered 350 Class A tertiary hospitals from 16 major cities in China. The data of antitumor drugs were divided into 3 categories by mechanism action: cytotoxic chemotherapy, molecular targeted therapeutic drugs, and other antitumor drugs. The usage characteristics of each category were analyzed through sales volume and sales value, and the characteristics of main drugs in each category were further analyzed.

RESULTS

During 2009-2011, the sales volume and sales value of antitumor drugs used in hospitals had markedly increased in China. Specifically, cytotoxic chemotherapy was the most prevalent category in clinical treatment, with total sales volume shares of 61.93%, 63.90%, and 68.40% during 2009-2011. Its share of total sales value was more than 70% in the same period. The sales volume share of molecular targeted therapeutic drugs was less than 1%, but the sales value share was about 20% in the corresponding period. In addition, plant alkaloids had become the leading subcategory of antitumor drugs in hospitals, which contributed 43.72% of total sales volume and 37% of total sales value in 2011. Antimetabolites still played an important role, with around 20% of sales volume, and monoclonal antibody and small-molecule compounds experienced rapid growth.

CONCLUSIONS

Plant alkaloids have become the most widely used antitumor drug for clinical medical treatment in China. In the future, monoclonal antibody and small-molecule compounds are expected to have wider usage in China.

Opalescence in monoclonal antibody solutions and its correlation with intermolecular interactions in dilute and concentrated solutions

Opalescence indicates physical instability of a formulation because of the presence of aggregates or liquid-liquid phase separation in solution and has been reported for monoclonal antibody (mAb) formulations. Increased solution opalescence can be attributed to attractive protein-protein interactions (PPIs). Techniques including light scattering, AUC, or membrane osmometry are routinely employed to measure PPIs in dilute solutions, whereas opalescence is seen at relatively higher concentrations, where both long- and short-range forces contribute to overall PPIs. The mAb molecule studied here shows a unique property of high opalescence because of liquid-liquid phase separation. In this study, opalescence measurements are correlated to PPIs measured in diluted and concentrated solutions using light scattering (kD ) and high-frequency rheology (G'), respectively. Charges on the molecules were calculated using zeta potential measurements. Results indicate that high opalescence and phase separation are a result of the attractive interactions in solution; however, the presence of attractive interactions do not always imply phase separation. Temperature dependence of opalescence suggests that thermodynamic contribution to opalescence is significant and Tcloud can be utilized as a potential tool to assess attractive interactions in solution.

Amino acid misincorporation in recombinant biopharmaceutical products

Microbial and mammalian host systems have been used extensively for the production of protein biotherapeutics. Generally these systems rely on the production of a specific gene sequence encoding one therapeutic product. Analysis of these protein products over many years has proven that this was not always the case, with multiple species of the intended product being produced due to amino acid misincorporation or mistranslation during biosynthesis of the protein. This review is the first to give a comprehensive overview of the occurrence and analysis of these misincorporations. Furthermore, using the latest data on misincorporation in native human proteins we explore potential considerations for producing a specification for misincorporation for the development of a human biotherapeutic protein product in a production environment.

A comparative study on the physicochemical and biological stability of IgG1 and monoclonal antibodies during spray drying process

Background

The main concern in formulation of antibodies is the intrinsic instability of these labile compounds. To evaluate the physicochemical stability of antibody in dry powder formulations, physical stability of IgG₁ and a monoclonal antibody (trastuzumab) during the spray drying process was studied in a parallel study and the efficacy of some sugar based excipients in protection of antibodies was studied.

Results

The SDS-PAGE analysis showed no fragmentation of antibodies after spray drying in all formulations. The secondary structure of antibodies contained 40.13 to 70.19% of β structure in dry state. Also, CD spectroscopy showed the similar secondary structure for trastuzumab after reconstitution in water. ELISA analysis and cell culture studies were conducted in order to evaluate bioactivity of monoclonal antibody. Formulations containing combination of excipients provided maximum tendency of trastuzumab to attach to the ELISA antigen (86.46% ± 2.3) and maximum bioactivity when incubated with SKBr₃ cell line (the cell viability was decreased to 65.99% ± 4.6). Incubation of formulations with L929 cell line proved the biocompatibility of the excipients and non-toxic composition of formulations.

Conclusion

The IgG₁ and trastuzumab demonstrated similar behavior in spray drying process. The combination of excipients containing trahalose, hydroxypropyl beta cyclodextrin and beta cyclodextrin with proper ratio improved the physical and chemical stability of both IgG₁ and monoclonal antibody.

Synthesis, bioanalysis and biodistribution of photosensitizer conjugates for photodynamic therapy

Photodynamic therapy (PDT) was discovered in 1900 by Raab, and has since emerged as a promising tool for treating diseases characterized by unwanted cells or hyperproliferating tissue (e.g., cancer or infectious disease). PDT consists of the light excitation of a photosensitizer (PS) in the presence of O(2) to yield highly reactive oxygen species. In recent years, PDT has been improved by the synthesis of targeted bioconjugates between monoclonal antibodies and PS, and by investigating PS biodistribution and PD. Here, we provide a comprehensive review of major developments in PS-immunoconjugate-based PDT and the bioanalysis of these agents, with a specific emphasis on anticancer and antimicrobial PDT.

Generation of human neutralizing monoclonal antibodies against the 2009 pandemic H1N1 virus from peripheral blood memory B lymphocytes

The 2009 H1N1 influenza pandemic demonstrated the significance of a global health threat to human beings. Although pandemic H1N1 vaccines have been rapidly developed, passive serotherapy may offer superior immediate protection against infections in children, the elderly and immune-compromised patients during an influenza pandemic. Here, we applied a novel strategy based on Epstein-Barr virus (EBV)-immortalized peripheral blood memory B cells to screen high viral neutralizing monoclonal antibodies (MAbs) from individuals vaccinated with the 2009 pandemic H1N1 vaccine PANFLU.1. Through a massive screen of 13 090 immortalized memory B-cell clones from three selected vaccinees, seven MAbs were identified with both high viral neutralizing capacities and hemagglutination inhibition (HAI) activities against the 2009 pandemic H1N1 viruses. These MAbs may have important clinical implications for passive serotherapy treatments of infected patients with severe respiratory syndrome, especially children, the elderly and immunodeficient individuals. Our successful strategy for generating high-affinity MAbs from EBV-immortalized peripheral blood memory B cells may also be applicable to other infectious or autoimmune diseases.

Structural basis for treating tumor necrosis factor α (TNFα)-associated diseases with the therapeutic antibody infliximab

BACKGROUND

Although infliximab has high efficacy in treating TNFα-associated diseases, the epitope on TNFα remains unclear.

RESULTS

The crystal structure of the TNFα in complex with the infliximab Fab is reported at a resolution of 2.6 Å.

CONCLUSION

TNFα E-F loop plays a crucial role in the interaction.

SIGNIFICANCE

The structure may lead to understanding the mechanism of mAb anti-TNFα Monoclonal antibody (mAb) drugs have been widely used for treating tumor necrosis factor α (TNFα)-related diseases for over 10 years. Although their action has been hypothesized to depend in part on their ability to bind precursor cell surface TNFα, the precise mechanism and the epitope bound on TNFα remain unclear. In the present work, we report the crystal structure of the infliximab Fab fragment in complex with TNFα at a resolution of 2.6 Å. The key features of the TNFα E-F loop region in this complex distinguish the interaction between infliximab and TNFα from other TNF-receptor structures, revealing the mechanism of TNFα inhibition by overlapping with the TNFα-receptor interface and indicating the crucial role of the E-F loop in the action of this therapeutic antibody. This structure also indicates the formation of an aggregated network for the activation of complement-dependent cytolysis and antibody-dependent cell-mediated cytotoxicity, which result in development of granulomatous infections through TNFα blockage. These results provide the first experimental model for the interaction of TNFα with therapeutic antibodies and offer useful information for antibody optimization by understanding the precise molecular mechanism of TNFα inhibition.

Monoclonal antibodies based on hybridoma technology

Based on the size and scope of the present global market for medicine, monoclonal antibodies (mAbs) have a very promising future, with applications for cancers through autoimmune ailments to infectious disease. Since mAbs recognize only their target antigens and not other unrelated proteins, pinpoint medical treatment is possible. Global demand is dramatically expanding. Hybridoma technology, which allows production of mAbs directed against antigens of interest is therefore privileged. However, there are some pivotal points for further development to generate therapeutic antibodies. One is selective generation of human mAbs. Employment of transgenic mice producing human antibodies would overcome this problem. Another focus is recognition sites and conformational epitopes in antigens may be just as important as linear epitopes, especially when membrane proteins such as receptors are targeted. Recognition of intact structures is of critical importance for medical purposes. In this review, we describe patent related information for therapeutic mAbs based on hybridoma technology and also discuss new advances in hybridoma technology that facilitate selective production of stereospecific mAbs.

Molecular characterization of novel trispecific ErbB-cMet-IGF1R antibodies and their antigen-binding properties

Therapeutic antibodies are well established drugs in diverse medical indications. Their success invigorates research on multi-specific antibodies in order to enhance drug efficacy by co-targeting of receptors and addressing key questions of emerging resistance mechanisms. Despite challenges in production, multi-specific antibodies are potentially more potent biologics for cancer therapy. However, so far only bispecific antibody formats have entered clinical phase testing. For future design of antibodies allowing even more targeting specificities, an understanding of the antigen-binding properties of such molecules is crucial. To this end, we have generated different IgG-like TriMAbs (trispecific, trivalent and tetravalent antibodies) directed against prominent cell surface antigens often deregulated in tumor biology. A combination of surface plasmon resonance and isothermal titration calorimetry techniques enables quantitative assessment of the antigen-binding properties of TriMAbs. We demonstrate that the kinetic profiles for the individual antigens are similar to the parental antibodies and all antigens can be bound simultaneously even in the presence of FcγRIIIa. Furthermore, cooperative binding of TriMAbs to their antigens was demonstrated. All antibodies are fully functional and inhibit receptor phosphorylation and cellular growth. TriMAbs are therefore ideal candidates for future applications in various therapeutic areas.

Transfer of engineered biophysical properties between different antibody formats and expression systems

Recombinant antibodies and their derivatives are receiving ever increasing attention for many applications. Nevertheless, they differ widely in biophysical properties, from stable monomers to metastable aggregation-prone mixtures of oligomers. Previous work from our laboratory presented the combination of structure-based analysis with family consensus alignments as being able to improve the properties of immunoglobulin variable domains. We had identified a series of mutations in the variable domains that greatly influenced both the stability and the expression level of single-chain Fv (scFv) fragments produced in the periplasm of Escherichia coli. We now investigated whether these effects are transferable to Fab fragments and immunoglobulin G (IgG) produced in bacteria, Pichia pastoris, and mammalian cells. Taken together, our data indicate that engineered mutations can increase functional expression levels only for periplasmic expression in prokaryotes. In contrast, stability against thermal and denaturant-induced unfolding is improved by the same mutations in all formats tested, including scFv, Fab and IgG, independent of the expression system. The mutations in V(H) also influenced the structural homogeneity of full-length IgG, and the reducibility of the distant C(H)1-C(L) inter-chain disulfide bond. These results confirm the potential of structure-based protein engineering in the context of full-length IgGs and the transferability of stability improvements discovered with smaller antibody fragments.

Russell body inducing threshold depends on the variable domain sequences of individual human IgG clones and the cellular protein homeostasis

Russell bodies are intracellular aggregates of immunoglobulins. Although the mechanism of Russell body biogenesis has been extensively studied by using truncated mutant heavy chains, the importance of the variable domain sequences in this process and in immunoglobulin biosynthesis remains largely unknown. Using a panel of structurally and functionally normal human immunoglobulin Gs, we show that individual immunoglobulin G clones possess distinctive Russell body inducing propensities that can surface differently under normal and abnormal cellular conditions. Russell body inducing predisposition unique to each immunoglobulin G clone was corroborated by the intrinsic physicochemical properties encoded in the heavy chain variable domain/light chain variable domain sequence combinations that define each immunoglobulin G clone. While the sequence based intrinsic factors predispose certain immunoglobulin G clones to be more prone to induce Russell bodies, extrinsic factors such as stressful cell culture conditions also play roles in unmasking Russell body propensity from immunoglobulin G clones that are normally refractory to developing Russell bodies. By taking advantage of heterologous expression systems, we dissected the roles of individual subunit chains in Russell body formation and examined the effect of non-cognate subunit chain pair co-expression on Russell body forming propensity. The results suggest that the properties embedded in the variable domain of individual light chain clones and their compatibility with the partnering heavy chain variable domain sequences underscore the efficiency of immunoglobulin G biosynthesis, the threshold for Russell body induction, and the level of immunoglobulin G secretion. We propose that an interplay between the unique properties encoded in variable domain sequences and the state of protein homeostasis determines whether an immunoglobulin G expressing cell will develop the Russell body phenotype in a dynamic cellular setting.

Methodologies for the isolation of alternative binders with improved clinical potentiality over conventional antibodies

The availability of binders to different functional domains of the same protein or to physiologically co-operating proteins allows for the simultaneous inhibition of independent downstream signaling pathways. This multi-target approach represents a promising therapeutic strategy, as demonstrated in the case of the synergistic effect of anti-Her2 treatment based on the combined use of the trastuzumab and pertuzumab monoclonal antibodies that induce cellular cytotoxicity and impair the receptor dimerization, respectively. Therefore, a reliable selection method for the recovery of epitope-specific antibodies is highly needed. Animal immunization with short peptides resembling the epitope sequence for raising conventional antibodies represents an alternative. Panning phage displayed libraries of recombinant antibodies such as scFvs and nanobodies or of other peptide collections is another option. Although recombinant antibodies can provide the same specificity as conventional antibodies, they offer at least two further advantages: i) the protocols for the selection of epitope-specific antibodies can be rationally designed, and ii) their expression as multivalent, bispecific and biparatopic molecules is feasible. This review will analyze the recent literature concerning technical aspects related to the isolation, the expression as multivalent molecules, and the therapeutic applications of binders able to interfere with antigen functional domains. The term binder will be preferred when possible to include those molecules, such as peptides or affibodies, with at least some proven practical uses.

Structure based antibody-like peptidomimetics

Biologics such as monoclonal antibodies (mAb) and soluble receptors represent new classes of therapeutic agents for treatment of several diseases. High affinity and high specificity biologics can be utilized for variety of clinical purposes. Monoclonal antibodies have been used as diagnostic agents when coupled with radionuclide, immune modulatory agents or in the treatment of cancers. Among other limitations of using large molecules for therapy the actual cost of biologics has become an issue. There is an effort among chemists and biologists to reduce the size of biologics which includes monoclonal antibodies and receptors without a reduction of biological efficacy. Single chain antibody, camel antibodies, Fv fragments are examples of this type of deconstructive process. Small high-affinity peptides have been identified using phage screening. Our laboratory used a structure-based approach to develop small-size peptidomimetics from the three-dimensional structure of proteins with immunoglobulin folds as exemplified by CD4 and antibodies. Peptides derived either from the receptor or their cognate ligand mimics the functions of the parental macromolecule. These constrained peptides not only provide a platform for developing small molecule drugs, but also provide insight into the atomic features of protein-protein interactions. A general overview of the reduction of monoclonal antibodies to small exocyclic peptide and its prospects as a useful diagnostic and as a drug in the treatment of cancer are discussed.

Hybridoma technology for the generation of monoclonal antibodies

Hybridoma technology has long been a remarkable and indispensable platform for generating high-quality monoclonal antibodies (mAbs). Hybridoma-derived mAbs have not only served as powerful tool reagents but also have emerged as the most rapidly expanding class of therapeutic biologics. With the establishment of mAb humanization and with the development of transgenic-humanized mice, hybridoma technology has opened new avenues for effectively generating humanized or fully human mAbs as therapeutics. In this chapter, an overview of hybridoma technology and the laboratory procedures used routinely for hybridoma generation are discussed and detailed in the following sections: cell fusion for hybridoma generation, antibody screening and characterization, hybridoma subcloning and mAb isotyping, as well as production of mAbs from hybridoma cells.

Engineering of affibody molecules for therapy and diagnostics

Affibody molecules are small and robust non-immunoglobulin affinity ligands capable of binding to a wide range of protein targets. They are selected from combinatorial libraries based on a 58 amino acid, three-alpha-helical Z-domain scaffold. They share no sequence or structural homologies to antibodies and in contrast to antibodies they can be functionally produced both by peptide synthesis and by recombinant expression in Escherichia coli. Protein engineering is used to adapt Affibody molecules binding to a target of interest to the specific demands imposed by the intended application. Obviously, the optimal molecule for molecular imaging will be different from the optimal molecule for therapy. Here, we describe general strategies to optimize Affibody molecules for diagnostic imaging and therapy applications.