Insights into the Molecular Basis of a Bispecific Antibody's Target Selectivity

Mazor Y, et al., 7(3):461-9, MAbs, 2015

A series of affinity-reduced variants of the anti-CD4 ibalizumab mAb were generated in order to understand target selectivity seen with bispecific antibodies. Particularly, the target selectivity of anti-CD4/CD70 DuetMab variants were evaluated for their binding affinities, selectivity, and depletion via antibody-dependent cell-mediated cytotoxicity (ADCC). A Pall ForteBio Octet RED384 system was used for antibody quantitation in cell-culture supernatants and affinity ranking of the variants. The binding of IgG and DuetMab to monomeric CD4 and CD70 were characterized by capturing IgGs on to anti-human IgG Fc biosensor probes and by titrating against serial dilutions of CD4 or CD70. Whereas for the DuetMab characterization, biotinylated CD4 and CD70 were captured onto Streptavidin Biosensor probes and analyzed against serial dilutions of DuetMab.

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