Single-domain antibody-based and linker-free bispecific antibodies targeting FcγRIII induce potent antitumor activity without recruiting regulatory T cells.

Antibody-dependent cell-mediated cytotoxicity, one of the most prominent modes of action of antitumor antibodies, suffers from important limitations due to the need for optimal interactions with Fcγ receptors. In this work, we report the design of a new bispecific antibody format, compact and linker-free, based on the use of llama single-domain antibodies that are capable of circumventing most of these limitations. This bispecific antibody format was created by fusing single-domain antibodies directed against the carcinoembryonic antigen and the activating FcγRIIIa receptor to human Cκ and CH1 immunoglobulin G1 domains, acting as a natural dimerization motif.

Cyclic peptides selected by phage display mimic the natural epitope recognized by a monoclonal anti-colicin A antibody.

A 10-mer random peptide library displayed on filamentous bacteriophage was used to determine the molecular basis of the interaction between the monoclonal anti-colicin A antibody 1C11 and its cognate epitope. Previous studies established that the putative epitope recognized by 1C11 antibody is composed of amino acid residues 19-25 (RGSGPEP) of colicin A. Using the phage display technique it was confirmed that the epitope of 1C11 antibody was indeed restricted to residues 19-25 and the consensus motif RXXXPEP was identified.

Functional characterization of an anti-estradiol antibody by site-directed mutagenesis and molecular modelling: modulation of binding properties and prominent role of the V(L) domain in estradiol recognition.

The high-affinity monoclonal anti-estradiol antibody 9D3 presents a specificity defect towards estradiol-3-sulphate and 3-glucuronide conjugates incompatible with use in direct immunoassays. The corresponding single-chain variable fragment (scFv), cloned and produced in E. coli, exhibited a 10-fold lower affinity for estradiol (K(a)=1.