A novel platform to produce human monoclonal antibodies: The next generation of therapeutic human monoclonal antibodies discovery

Antibody-Based Immunotherapies as a Tool for Tackling Multidrug-Resistant Bacterial Infections

The discovery of antimicrobials is an outstanding achievement of mankind that led to the development of modern medicine. However, increasing antimicrobial resistance observed worldwide is rendering commercially available antimicrobials ineffective. This problem results from the bacterial ability to adapt to selective pressure, leading to the development or acquisition of multiple types of resistance mechanisms that can severely affect the efficacy of antimicrobials. The misuse, over-prescription, and poor treatment adherence by patients are factors strongly aggravating this issue, with an epidemic of infections untreatable by first-line therapies occurring over decades. Alternatives are required to tackle this problem, and immunotherapies are emerging as pathogen-specific and nonresistance-generating alternatives to antimicrobials. In this work, four types of antibody formats and their potential for the development of antibody-based immunotherapies against bacteria are discussed. These antibody isotypes include conventional mammalian polyclonal antibodies that are used for the neutralization of toxins; conventional mammalian monoclonal antibodies that currently have 100 IgG mAbs approved for therapeutic use; immunoglobulin Y found in birds and an excellent source of high-quality polyclonal antibodies able to be purified noninvasively from egg yolks; and single domain antibodies (also known as nanobodies), a recently discovered antibody format (found in camelids and nurse sharks) that allows for a low-cost synthesis in microbial systems, access to hidden or hard-to-reach epitopes, and exhibits a high modularity for the development of complex structures.

Targeting Mast Cells in Allergic Disease: Current Therapies and Drug Repurposing

The incidence of allergic disease has grown tremendously in the past three generations. While current treatments are effective for some, there is considerable unmet need. Mast cells are critical effectors of allergic inflammation. Their secreted mediators and the receptors for these mediators have long been the target of allergy therapy. Recent drugs have moved a step earlier in mast cell activation, blocking IgE, IL-4, and IL-13 interactions with their receptors. In this review, we summarize the latest therapies targeting mast cells as well as new drugs in clinical trials. In addition, we offer support for repurposing FDA-approved drugs to target mast cells in new ways. With a multitude of highly selective drugs available for cancer, autoimmunity, and metabolic disorders, drug repurposing offers optimism for the future of allergy therapy.

Immunization and Immunotherapy Approaches against Pseudomonas aeruginosa and Burkholderia cepacia Complex Infections

Human infections caused by the opportunist pathogens Burkholderia cepacia complex and Pseudomonas aeruginosa are of particular concern due to their severity, their multiple antibiotic resistance, and the limited eradication efficiency of the current available treatments. New therapeutic options have been pursued, being vaccination strategies to prevent or limit these infections as a rational approach to tackle these infections. In this review, immunization and immunotherapy approaches currently available and under study against these bacterial pathogens is reviewed. Ongoing active and passive immunization clinical trials against P. aeruginosa infections is also reviewed. Novel identified bacterial targets and their possible exploitation for the development of immunization and immunotherapy strategies against P. aeruginosa and B. cepacia complex and infections are also presented and discussed.

Investigation of interactions between binding residues and solubility of grafted humanized anti-VEGF IgG antibodies expressed as full-length format in the cytoplasm of a novel engineered E. coli SHuffle strain

Monoclonal antibodies (mAbs) are one of the fastest-growing areas of biopharmaceutical industry and have been widely used for a broad spectrum of diseases. Meanwhile, the immunogenicity of non-human derived antibodies can generate side effects by inducing the human immune response to produce human anti-mouse-immunoglobulin antibody (HAMA). In this work, we aim to reduce the immunogenicity of muMAb A.4.6.1 by substitute human sequences for murine sequences. Humanized antibodies are constructed by grafting, specificity determining residues (SDR), complementary determining regions (CDR), and chimeric region of muMAb A.4.6.1, onto variable domain of Trastuzumab (Herceptin). The interactions between grafted antibodies and their target, Vascular endothelial growth factor (VEGF), were theoretically investigated by molecular dynamics simulation in order to evaluate the antibodies-antigen binding behavior. The obtained protein-protein interactions and calculated binding free energy suggested that the SDR-VEGF complex presented a significantly greater binding affinity, number of contact and total number of H-bonds compared to CDR and chimeric mAbs, significantly. Moreover, the Camsol program predicted that the solubility of SDR mAb exhibits the greatest solubility. This result was supported by performing a western blot analysis of the grafted mAbs with soluble and insoluble fractions in order to evaluate their solubility, in which SDR was found to have a much lower amount of insoluble proteins. Consequently, the enhanced binding affinity and solubility of the designed SDR was achieved by the single S106D mutation using computational methods. With the aim of low immunogenicity, high solubility, and high affinity, this SDR humanized antibody was expected to have greater efficacy than murine or chimeric antibodies for future use in humans.

Preclinical optimization of antibody-based radiopharmaceuticals for cancer imaging and radionuclide therapy-Model, vector, and radionuclide selection

Intact antibodies and their truncated counterparts (eg, Fab, scFv fragments) are generally exquisitely specific and selective vectors, enabling recognition of individual cancer-associated molecular phenotypes against a complex and dynamic biomolecular background. Complementary alignment of these advantages with unique properties of radionuclides is a defining paradigm in both radioimmunoimaging and radioimmunotherapy, which remain some of the most adept and promising tools for cancer diagnosis and treatment. This review discusses how translational potency can be maximized through rational selection of antibody-nuclide couples for radioimmunoimaging/therapy in preclinical models.

Computationally driven antibody engineering enables simultaneous humanization and thermostabilization

Humanization reduces the immunogenicity risk of therapeutic antibodies of non-human origin. Thermostabilization can be critical for clinical development and application of therapeutic antibodies. Here, we show that the computational antibody redesign method Computationally Driven Antibody Humanization (CoDAH) enables these two goals to be accomplished simultaneously and seamlessly. A panel of CoDAH designs for the murine parent of cetuximab, a chimeric anti-EGFR antibody, exhibited both substantially improved thermostabilities and substantially higher levels of humanness, while retaining binding activity near the parental level. The consistently high quality of the turnkey CoDAH designs, over a whole panel of variants, suggests that the computationally directed approach encapsulates key determinants of antibody structure and function.

Antibody humanization by structure-based computational protein design

Antibodies derived from non-human sources must be modified for therapeutic use so as to mitigate undesirable immune responses. While complementarity-determining region (CDR) grafting-based humanization techniques have been successfully applied in many cases, it remains challenging to maintain the desired stability and antigen binding affinity upon grafting. We developed an alternative humanization approach called CoDAH ("Computationally-Driven Antibody Humanization") in which computational protein design methods directly select sets of amino acids to incorporate from human germline sequences to increase humanness while maintaining structural stability. Retrospective studies show that CoDAH is able to identify variants deemed beneficial according to both humanness and structural stability criteria, even for targets lacking crystal structures. Prospective application to TZ47, a murine anti-human B7H6 antibody, demonstrates the approach. Four diverse humanized variants were designed, and all possible unique VH/VL combinations were produced as full-length IgG1 antibodies. Soluble and cell surface expressed antigen binding assays showed that 75% (6 of 8) of the computationally designed VH/VL variants were successfully expressed and competed with the murine TZ47 for binding to B7H6 antigen. Furthermore, 4 of the 6 bound with an estimated KD within an order of magnitude of the original TZ47 antibody. In contrast, a traditional CDR-grafted variant could not be expressed. These results suggest that the computational protein design approach described here can be used to efficiently generate functional humanized antibodies and provide humanized templates for further affinity maturation.

Engineering aggregation-resistant antibodies

The ability of antibodies to bind to target molecules with high affinity and specificity has led to their widespread use in diagnostic and therapeutic applications. Nevertheless, a limitation of antibodies is their propensity to self-associate and aggregate at high concentrations and elevated temperatures. The large size and multidomain architecture of full-length monoclonal antibodies have frustrated systematic analysis of how antibody sequence and structure regulate antibody solubility. In contrast, analysis of single and multidomain antibody fragments that retain the binding activity of mono-clonal antibodies has provided valuable insights into the determinants of antibody aggregation. Here we review advances in engineering antibody frameworks, domain interfaces, and antigen-binding loops to prevent aggregation of natively and nonnatively folded antibody fragments. We also highlight advances and unmet challenges in developing robust strategies for engineering large, multidomain antibodies to resist aggregation.