Development and activities, including immunocomplex formation, of biparatopic antibodies and alternative scaffold proteins

Abstract

Biparatopic antibodies and biparatopic alternative scaffolds are proteins that can simultaneously bind two distinct epitopes, and as such are promising formats for the development of next-generation antibody therapeutics. By design, biparatopic proteins have high avidity and can bridge between epitopes in an intra-or intermolecular manner to form diverse immunocomplexes. Some biparatopic proteins can be efficiently internalized into cells, which may be useful for the targeted delivery of therapeutic molecules into cells. In addition, biparatopic proteins can also lock the conformation of membrane proteins to exert an agonist or antagonist effect. Here, we review the development and characteristics of biparatopic proteins and examine how they differ in terms of antigen-binding efficiency, immunocomplex formation and biological activity compared with conventional monoparatopic proteins.

Development of a 1:1-binding biparatopic anti-TNFR2 antagonist by epitope selection

“…This is consistent with reported BpAbs bridging multiple antigen molecules and utilized as agonists for cell-surface proteins, including TNFRSF (Fig. 1D, left) (17)(18)(19)(20). It should be noted that all five cIgGs were moderately agonistic, as predicted based on their bivalency.…”

“…Recent advances in antibody engineering have paved the way to regulate the stoichiometry and size of complexes between antigen and antibody molecules (22). As one of the most promising techniques, artificial BpAbs have overcome the limitations of cIgGs by releasing the restriction of bivalency (17)(18)(19)(20). Manipulating the size of the complex enables BpAbs against cell-surface receptors to control intracellular signaling on a mechanistic basis.…”

“…S6). Increased apparent binding affinity by designing BpAbs is common ( 19 ), including the case of estimated 1:1 binding with trimeric viral antigens ( 24,25 ). Although 1:1 binding may not be required for the biological activities of these antibodies, our results provide the first evidence that the exclusive formation of a specific 1:1 complex is required for biological significance.…”

Characterization of a novel format scFv×VHH single‐chain biparatopic antibody against metal binding protein MtsA

“…Among the bispecific antibodies, biparatopic antibodies (bpAbs) are artificially modified multispecific antibodies that have multiple different epitopes within the same antigen, allowing a single antibody molecule to bind to different sites of the target antigen simultaneously. Compared with monoclonal antibodies, which can only bind to single sites of an antigen, bpAbs can increase binding avidity and exhibit distinct antigen–antibody complex formation (Akiba & Tsumoto, 2020 ). The format of bpAbs varies widely, but they are classified into two groups: immunoglobulin G‐like containing the Fc region and fragment‐based without the Fc region (Brinkmann & Kontermann, 2017 ; Labrijn et al, 2019 ).…”

Computational Construction of a Single-Chain Bi-Paratopic Antibody Allosterically Inhibiting TCR-Staphylococcal Enterotoxin B Binding

“…The bispecific scFV can be commonly used to target two separate targets to activate T-cell in cancer immunetherapy (8), or bind two protomers in HIV-1 envelope glycoproteins trimer complex (9). Biparatopic bispecific antibodies recognize two different epitopes on one molecule and are promising formats for the development of next-generation antibody therapeutics (10)(11)(12)(13). Therefore, it is interesting to examine a novel approach to use a biparatopic antibody to target Staphylococcal enterotoxin B (SEB), a small single domain protein with at least four non-overlapping epitopes.…”