Characterizations of a neutralizing antibody broadly reactive to multiple gluten peptide:HLA-DQ2.5 complexes in the context of celiac disease.

In human celiac disease (CeD) HLA-DQ2.5 presents gluten peptides to antigen-specific CD4+ T cells, thereby instigating immune activation and enteropathy. Targeting HLA-DQ2.5 with neutralizing antibody for treating CeD may be plausible, yet using pan-HLA-DQ antibody risks affecting systemic immunity, while targeting selected gluten peptide:HLA-DQ2.5 complex (pHLA-DQ2.5) may be insufficient. Here we generate a TCR-like, neutralizing antibody (DONQ52) that broadly recognizes more than twenty-five distinct gluten pHLA-DQ2.5 through rabbit immunization with multi-epitope gluten pHLA-DQ2.5 and multidimensional optimization. Structural analyses show that the proline-rich and glutamine-rich motif of gluten epitopes critical for pathogenesis is flexibly recognized by multiple tyrosine residues present in the antibody paratope, implicating the mechanisms for the broad reactivity. In HLA-DQ2.5 transgenic mice, DONQ52 demonstrates favorable pharmacokinetics with high subcutaneous bioavailability, and blocks immunity to gluten while not affecting systemic immunity. Our results thus provide a rationale for clinical testing of DONQ52 in CeD.

Comprehensive engineering of a therapeutic neutralizing antibody targeting SARS-CoV-2 spike protein to neutralize escape variants.

The emergence of escape variants of SARS-CoV-2 carrying mutations in the spike protein poses a challenge for therapeutic antibodies. Here, we show that through the comprehensive engineering of the variable region of the neutralizing monoclonal antibody 5A6, the engineered antibody, 5A6CCS1, is able to neutralize SARS-CoV-2 variants that escaped neutralization by the original 5A6 antibody. In addition to the improved affinity against variants, 5A6CCS1 was also optimized to achieve high solubility and low viscosity, enabling a high concentration formulation for subcutaneous injection. In cynomolgus monkeys, 5A6CCS1 showed a long plasma half-life and good subcutaneous bioavailability through engineering of the variable and constant region. These data demonstrate that 5A6CCS1 is a promising antibody for development against SARS-CoV-2 and highlight the importance of antibody engineering as a potential method to counteract escape variants.

Fc Engineering to Improve the Function of Therapeutic Antibodies.

Monoclonal antibodies are currently the most attractive therapeutic modality in a broad range of disease areas, including infectious diseases, autoimmune diseases, and oncology. Fc engineering is one attractive application to maximize the value or overcome the drawbacks of monoclonal antibodies for therapeutic use. With the Fc region, antibodies bind to several types of receptors, such as Fc gamma receptors, a complement receptor, and a neonatal Fc receptor. Through this interaction with the receptors, antibodies demonstrate unique functions, such as antibody-dependent cellular cytotoxicity, antibody- dependent cellular phagocytosis, complement dependent cytotoxicity, agonistic activity, and endosomal recycling. Fc engineering technology is conducted mainly to maximize the receptor-mediated functions of antibodies. Moreover, Fc engineering of the two heavy chains to facilitate heterodimerization is indispensable for generating IgG-like bispecific antibodies that are asymmetric. Fc engineering is also conducted to avoid the undesired properties, such as cytokine release and protease-mediated cleavage of the hinge region, of wild-type antibodies, as well as providing additional functions. Thus, Fc engineering technology is an attractive approach for maximizing the potency and convenience of therapeutic antibodies. This review will cover a variety of Fc engineering technologies that improve the functions of therapeutic antibodies.

Novel asymmetrically engineered antibody Fc variant with superior FcγR binding affinity and specificity compared with afucosylated Fc variant.

Fc engineering is a promising approach to enhance the antitumor efficacy of monoclonal antibodies (mAbs) through antibody-dependent cell-mediated cytotoxicity (ADCC). Glyco- and protein-Fc engineering have been employed to enhance FcγR binding and ADCC activity of mAbs; the drawbacks of previous approaches lie in their binding affinity to both FcγRIIIa allotypes, the ratio of activating FcγR binding to inhibitory FcγR binding (A/I ratio) or the melting temperature (T(M)) of the C(H)2 domain. To date, no engineered Fc variant has been reported that satisfies all these points. Herein, we present a novel Fc engineering approach that introduces different substitutions in each Fc domain asymmetrically, conferring optimal binding affinity to FcγR and specificity to the activating FcγR without impairing the stability. We successfully designed an asymmetric Fc variant with the highest binding affinity for both FcγRIIIa allotypes and the highest A/I ratio compared with previously reported symmetrically engineered Fc variants, and superior or at least comparable in vitro ADCC activity compared with afucosylated Fc variants. In addition, the asymmetric Fc engineering approach offered higher stability by minimizing the use of substitutions that reduce the T(M) of the C(H)2 domain compared with the symmetric approach. These results demonstrate that the asymmetric Fc engineering platform provides best-in-class effector function for therapeutic antibodies against tumor antigens.